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Sample records for hydrogenation catalysts based

  1. Review on Copper and Palladium Based Catalysts for Methanol Steam Reforming to Produce Hydrogen

    OpenAIRE

    Xinhai Xu; Kaipeng Shuai; Ben Xu

    2017-01-01

    Methanol steam reforming is a promising technology for producing hydrogen for onboard fuel cell applications. The methanol conversion rate and the contents of hydrogen, carbon monoxide and carbon dioxide in the reformate, significantly depend on the reforming catalyst. Copper-based catalysts and palladium-based catalysts can effectively convert methanol into hydrogen and carbon dioxide. Copper and palladium-based catalysts with different formulations and compositions have been thoroughly inve...

  2. Development of a Practical Hydrogen Storage System Based on Liquid Organic Hydrogen Carriers and a Homogeneous Catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Craig [Hawaii Hydrogen Carriers, LLC, Honolulu, HI (United States); Brayton, Daniel [Hawaii Hydrogen Carriers, LLC, Honolulu, HI (United States); Jorgensen, Scott W. [General Motors, LLC, Warren, MI (United States). Research and Development Center. Chemical and Material Systems Lab.; Hou, Peter [General Motors, LLC, Warren, MI (United States). Research and Development Center. Chemical and Material Systems Lab.

    2017-03-24

    The objectives of this project were: 1) optimize a hydrogen storage media based on LOC/homogeneous pincer catalyst (carried out at Hawaii Hydrogen Carriers, LLC) and 2) develop space, mass and energy efficient tank and reactor system to house and release hydrogen from the media (carried out at General Motor Research Center).

  3. Hydrogen from ethylene glycol by supercritical water reforming supported noble and base metal catalysts

    NARCIS (Netherlands)

    de Vlieger, Dennis; Chakinala, A.G.; Lefferts, Leonardus; Kersten, Sascha R.A.; Seshan, Kulathuiyer; Brilman, Derk Willem Frederik

    2012-01-01

    Catalytic reforming of ethylene glycol (5 and 15 wt%) in supercritical water (450 °C and 250 bar) in the presence of alumina supported mono- and bi-metallic catalysts based on Ir, Pt and Ni was studied. Pt catalyst showed the highest hydrogen yields compared to Ir and Ni. Varying the Pt loading

  4. Hydrogen spillover phenomenon in noble metal modified clay-based hydrocracking catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Ali, M.A.; Al-Saleh, M.A.; Hamid, H. [Center for Refining and Petrochemicals, Research Institute, King Fahd University of Petroleum and Minerals, 31261 Dhahran (Saudi Arabia); Kimura, T.; Suzuki, Y.; Inui, T. [Petroleum Energy Center, Tokyo (Japan)

    2002-03-08

    Homemade clay-based catalysts and a commercial hydrocracking catalyst were evaluated for hydrocracking activity using vacuum gas oil (VGO) from Saudi Arabian light crude oil. The clay-based catalysts were prepared in our laboratories by cobalt loading and one of them was impregnated with a noble metal belonging to group VIII of the periodic table. The reactions were conducted in both flow and batch reaction system. The amount of saturates were found to increase while aromatics and polars were decreasing with the increase in conversion of feed to lighter products. The cracking activities of both clay-based catalysts were found better than the catalyst C (commercial). In the flow reactor, at 360C reaction temperature, the activity of catalyst A (having noble metal) was 2 times more than that of the catalyst B (without noble metal), while 2.5 times more than that of the commercial catalyst. Similarly, at 380 and 400C temperatures, the activity of catalyst A was 2 times more than that of the catalyst C and substantially higher than that of catalyst B. In the batch reactor, higher cracking and HDS activity were observed for catalyst A and more saturates were found in the reaction product as well. The amount of carbon deposited was found to be lower on the spent clay catalyst A. This study clearly shows that even in hydrocracking of VGO which contains complex hydrocarbons and substantial amounts of sulfur, nitrogen and metals, hydrogen spillover phenomena do occur.

  5. Review on Copper and Palladium Based Catalysts for Methanol Steam Reforming to Produce Hydrogen

    Directory of Open Access Journals (Sweden)

    Xinhai Xu

    2017-06-01

    Full Text Available Methanol steam reforming is a promising technology for producing hydrogen for onboard fuel cell applications. The methanol conversion rate and the contents of hydrogen, carbon monoxide and carbon dioxide in the reformate, significantly depend on the reforming catalyst. Copper-based catalysts and palladium-based catalysts can effectively convert methanol into hydrogen and carbon dioxide. Copper and palladium-based catalysts with different formulations and compositions have been thoroughly investigated in the literature. This work summarized the development of the two groups of catalysts for methanol steam reforming. Interactions between the activity components and the supports as well as the effects of different promoters were discussed. Compositional and morphological characteristics, along with the methanol steam reforming performances of different Cu/ZnO and Pd/ZnO catalysts promoted by Al2O3, CeO2, ZrO2 or other metal oxides, were reviewed and compared. Moreover, the reaction mechanism of methanol steam reforming over the copper based and palladium based catalysts were discussed.

  6. Acetaldehyde behavior over platinum based catalyst in hydrogen stream generated by ethanol reforming

    Energy Technology Data Exchange (ETDEWEB)

    de Lima, Adriana F.F. [Laboratorio de Catalise, Instituto Nacional de Tecnologia, Av. Venezuela 82/507, 20081-310 Rio de Janeiro, RJ (Brazil); Instituto de Quimica e INOG (Instituto Nacional de Oleo Gas), UERJ-CNPq, FAPERJ, Universidade do Estado do Rio de Janeiro, Rua Sao Francisco Xavier, 524, 20550-900 Rio de Janeiro, RJ (Brazil); Colman, Rita C. [Departamento de Engenharia Quimica e de Petroleo, Universidade Federal Fluminense, Av. Passos da Patria, 156/bl E/240, 24210-240 Niteroi, RJ (Brazil); Zotin, Fatima M.Z. [Instituto de Quimica e INOG (Instituto Nacional de Oleo Gas), UERJ-CNPq, FAPERJ, Universidade do Estado do Rio de Janeiro, Rua Sao Francisco Xavier, 524, 20550-900 Rio de Janeiro, RJ (Brazil); CETEM-MCT, Av. Pedro Calmon, 900, Cidade Universitaria, 21941-908 Rio de Janeiro, RJ (Brazil); Appel, Lucia G. [Laboratorio de Catalise, Instituto Nacional de Tecnologia, Av. Venezuela 82/507, 20081-310 Rio de Janeiro, RJ (Brazil)

    2010-12-15

    Due to the greenhouse effect, hydrogen production from bioethanol reforming is a very important subject in heterogeneous catalysis research. Pt based catalysts are employed in H{sub 2} purification processes and also as electrocatalysts of PEM (''Proton Exchange Membrane'') fuel cells. Hydrogen obtained from ethanol reforming may contain, as contaminants, acetaldehyde and small amounts of CO. This aldehyde can be decarbonylated on Pt based catalysts generating carbon monoxide and methane, rendering the hydrogen purification more challenging. Moreover, acetaldehyde might also change the electrocatalyst behavior. Therefore, this contribution aims at studying the acetaldehyde behavior in the presence of platinum based catalysts in hydrogen atmosphere. The Pt/SiO{sub 2}, Pt/USY catalysts and an electrocatalyst were characterized by n-butylamine, H{sub 2} and CO{sub 2} adsorption, ATG/DTG measurements and cyclohexane dehydrogenation reaction. It was observed that the acid-basic properties of the supports promote condensation reactions. When in contact with Pt based catalysts, acetaldehyde undergoes C-C and C=O bond scissions. The former occurs at a wide range of temperatures, whereas the latter only at low temperatures (<200 C). The C-C bond scission (decarbonylation) produces methane and CO. The C=O bond scission generates carbon residues on the catalyst as well as oxygen species, which in turn is able to eliminate CO from the catalytic surface. The data also show that decarbonylation is not a structure-sensitive reaction. (author)

  7. Hydrogen evolution reaction catalyst

    Science.gov (United States)

    Subbaraman, Ram; Stamenkovic, Vojislav; Markovic, Nenad; Tripkovic, Dusan

    2016-02-09

    Systems and methods for a hydrogen evolution reaction catalyst are provided. Electrode material includes a plurality of clusters. The electrode exhibits bifunctionality with respect to the hydrogen evolution reaction. The electrode with clusters exhibits improved performance with respect to the intrinsic material of the electrode absent the clusters.

  8. Electroless Nickel-Based Catalyst for Diffusion Limited Hydrogen Generation through Hydrolysis of Borohydride

    Directory of Open Access Journals (Sweden)

    Shannon P. Anderson

    2013-07-01

    Full Text Available Catalysts based on electroless nickel and bi-metallic nickel-molybdenum nanoparticles were synthesized for the hydrolysis of sodium borohydride for hydrogen generation. The catalysts were synthesized by polymer-stabilized Pd nanoparticle-catalyzation and activation of Al2O3 substrate and electroless Ni or Ni-Mo plating of the substrate for selected time lengths. Catalytic activity of the synthesized catalysts was tested for the hydrolyzation of alkaline-stabilized NaBH4 solution for hydrogen generation. The effects of electroless plating time lengths, temperature and NaBH4 concentration on hydrogen generation rates were analyzed and discussed. Compositional analysis and surface morphology were carried out for nano-metallized Al2O3 using Scanning Electron Micrographs (SEM and Energy Dispersive X-Ray Microanalysis (EDAX. The as-plated polymer-stabilized electroless nickel catalyst plated for 10 min and unstirred in the hydrolysis reaction exhibited appreciable catalytic activity for hydrolysis of NaBH4. For a zero-order reaction assumption, activation energy of hydrogen generation using the catalyst was estimated at 104.6 kJ/mol. Suggestions are provided for further work needed prior to using the catalyst for portable hydrogen generation from aqueous alkaline-stabilized NaBH4 solution for fuel cells.

  9. Co-Production of Electricity and Hydrogen Using a Novel Iron-based Catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Hilaly, Ahmad; Georgas, Adam; Leboreiro, Jose; Arora, Salil; Head, Megann; Trembly, Jason; Turk, Brian; Gupta, Raghubir

    2011-09-30

    The primary objective of this project was to develop a hydrogen production technology for gasification applications based on a circulating fluid-bed reactor and an attrition resistant iron catalyst. The work towards achieving this objective consisted of three key activities: Development of an iron-based catalyst suitable for a circulating fluid-bed reactor; Design, construction, and operation of a bench-scale circulating fluid-bed reactor system for hydrogen production; Techno-economic analysis of the steam-iron and the pressure swing adsorption hydrogen production processes. This report describes the work completed in each of these activities during this project. The catalyst development and testing program prepared and iron-based catalysts using different support and promoters to identify catalysts that had sufficient activity for cyclic reduction with syngas and steam oxidation and attrition resistance to enable use in a circulating fluid-bed reactor system. The best performing catalyst from this catalyst development program was produced by a commercial catalyst toll manufacturer to support the bench-scale testing activities. The reactor testing systems used during material development evaluated catalysts in a single fluid-bed reactor by cycling between reduction with syngas and oxidation with steam. The prototype SIP reactor system (PSRS) consisted of two circulating fluid-bed reactors with the iron catalyst being transferred between the two reactors. This design enabled demonstration of the technical feasibility of the combination of the circulating fluid-bed reactor system and the iron-based catalyst for commercial hydrogen production. The specific activities associated with this bench-scale circulating fluid-bed reactor systems that were completed in this project included design, construction, commissioning, and operation. The experimental portion of this project focused on technical demonstration of the performance of an iron-based catalyst and a

  10. Simultaneous hydrodesulfurization, hydrodenitrogenation, hydrogenolysis and hydrogenation over MoS{sub 2}-based catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Wang, W.; Wei, B.; Song, C.

    1999-07-01

    Simultaneous hydrodesulfurization (HDS), hydrodenitrogenation (HDN), hydrogenolysis (HYC) and hydrogenation (HYG) of model compounds were studied under high pressure with MoS{sub 2}-based catalysts. Such reactions are related to conversion of coal, heavy oil and resid as well as waste materials. Three metal sulfide catalysts have been examined, including dispersed MoS{sub 2} catalyst derived in-situ from ammonium tetrathiomolybdate [ATTM, (NH{sub 4}){sub 2}MoS{sub 4}] and sulfided Co-Mo/Al{sub 2}O{sub 3} (CR-344) and Ni-Mo/Al{sub 2}O{sub 3} (CR-424) catalysts from Criterion. In order to investigate the catalytic functions of these catalysts and the influence of co-reactants, five model compounds were examined both as individual reactants and as 5-component mixture in this work, including (1) 4-(1-naphthylmethyl)bibenzyl (100%), abbreviated as NMBB, (2) pyrene (99%), (3) dibenzothiophene (98%), abbreviated as DBT, (4) quinoline (99%), and (5) eicosane (99%). The experiments with 5-component mixture showed that the patterns of product distributions strongly depend on the type of catalysts, and the trends do not always parallel with those for single-component tests, indicating the influence of co-reactants. In general, pyrene and eicosane were hardest to convert in the mixtures. The dispersed MoS{sub 2} catalyst (ATTM as precursor) showed higher capabilities on HDN and hydrogenation of pyrene, but lower HDS/conversion of DBT. Compared with the other two catalysts, CR-424 was much more active for NMBB conversion than for pyrene conversion. Overall, CR-424 catalyst appears to be the most effective on HDS, HDN and on hydrogenolysis of C-C bond in NMBB.

  11. Catalytic Cracking of Heavy Oil with Iron Oxide-based Catalysts Using Hydrogen and Oxygen Species from Steam

    National Research Council Canada - National Science Library

    Eri Fumoto; Yoshikazu Sugimoto; Shinya Sato; Toshimasa Takanohashi

    2015-01-01

      This study investigated the transfer of oxygen and hydrogen species from steam to product during the catalytic cracking of heavy oil with iron oxide-based catalysts containing zirconia and alumina...

  12. Active Hydrogenation Catalyst with a Structured, Peptide-Based Outer-Coordination Sphere

    Energy Technology Data Exchange (ETDEWEB)

    Jain, Avijita; Buchko, Garry W.; Reback, Matthew L.; O' Hagan, Molly J.; Ginovska-Pangovska, Bojana; Linehan, John C.; Shaw, Wendy J.

    2012-10-05

    The synthesis, catalytic activity, and structural features of a rhodium-based hydrogenation catalyst containing a phosphine ligand coupled to a 14-residue peptide are reported. Both CD and NMR spectroscopy show that the peptide adopts a helical structure in 1:1:1 TFE/MeCN/H2O that is maintained when the peptide is attached to the ligand and when the ligand is attached to the metal complex. The metal complex hydrogenates aqueous solutions of 3-butenol to 1-butanol at 360 ± 50 turnovers/Rh/h at 294 K. This peptide- based catalyst represents a starting point for developing and characterizing a peptide-based outer-coordination sphere that can be used to introduce enzyme-like features into molecular catalysts. This work was funded by the US DOE Basic Energy Sciences, Chemical Sciences, Geoscience and Biosciences Division (AJ, JCL and WJS), the Office of Science Early Career Research Program through the Office of Basic Energy Sciences (GWB, MLR and WJS). Part of the research was conducted at the W.R. Wiley Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by U.S. Department of Energy’s Office of Biolog-ical and Environmental Research (BER) program located at Pacific Northwest National Laboratory (PNNL). PNNL is operated by Battelle for the U.S. Department of Energy.

  13. Hydrogenation of Ethyl Acetate to Ethanol over Ni-Based Catalysts Obtained from Ni/Al Hydrotalcite-Like Compounds

    Directory of Open Access Journals (Sweden)

    Longfei Jiang

    2010-07-01

    Full Text Available A series of Ni-based catalysts were prepared using hydrogen reduction of Ni/Al hydrotalcite-like compounds (Ni/Al HTlcs synthesized by coprecipitation. The physico-chemical properties of Ni/Al hydrotalcite-like compounds and the corresponding Ni-based catalysts were characterized using inductively coupled plasma (ICP, BET surface areas, X-ray diffraction (XRD, Fourier transform infrared (FTIR spectroscopy and scanning electron microscopy (SEM techniques. The results indicated that Ni/Al HTlcs with layered structures could be successfully prepared by the coprecipitation method, and the characteristic HTlcs reflections were also observed in the XRD analysis. The NiO and Ni0 phases were identified in all Ni-based catalysts, which displayed randomly interconnected pores and no layer structures. In addition, the studies also found the Ni/Al HTlcs and Ni-based catalysts had high specific surface areas, low pore volumes and low pore diameters. The catalytic hydrogenation of ethyl acetate to ethanol with Ni-based catalysts was also investigated. Among the studied catalysts, RE1NASH-110-3 showed the highest selectivity and yield of ethyl acetate to ethanol, which were 68.2% and 61.7%, respectively. At the same time, a major by-product, butyl acetate, was formed due to an ester-exchange reaction. A proposed hydrogenation pathway for ethyl acetate over Ni-based catalysts was suggested.

  14. Thermochemical hydrogen sensor based on Pt-coated nanofiber catalyst deposited on pyramidally textured thermoelectric film

    Science.gov (United States)

    Kim, Seil; Song, Yoseb; Lee, Young-In; Choa, Yong-Ho

    2017-09-01

    The hydrogen gas-sensing performance has been systemically investigated of a new type of thermochemical hydrogen (TCH) sensor, composed of pyramidally textured thermoelectric (TE) film and catalytic Pt-coated nanofibers (NFs) deposited over the TE film. The TE film was composed of stoichiometric Bi2Te3, synthesized by means of cost-effective electrochemical deposition onto a textured silicon wafer. The resulting pyramidally textured TE film played a critical role in maximizing hydrogen gas flow around the overlying Pt NFs, which were synthesized by means of electrospinning followed by sputtering and acted as a heating catalyst. The optimal temperature increase of the Pt NFs was determined by means of optimizations of the electrospinning and sputtering durations. The output voltage signal of the optimized TCH sensor based on Pt NFs was 17.5 times higher than that of a Pt thin film coated directly onto the pyramidal TE material by using the same sputtering duration, under the fixed conditions of 3 vol% H2 in air at room temperature. This observation can be explained by the increased surface area of (111) planes accessible on the Pt-coated NFs. The best response time and recovery time observed for the optimized TCH sensor based on Pt-coated NFs were respectively 17 and 2 s under the same conditions. We believe that this type of TCH sensor can be widely used for supersensitive hydrogen gas detection by employing small-size Pt NFs and various chalcogenide thin films with high thermoelectric performance.

  15. Hydrogenation of CO2 to methanol using copper/zinc oxide-based catalyst: Effect of active metal ratio

    Science.gov (United States)

    Zabidi, Noor Asmawati Mohd; Tasfy, Sara; Shaharun, Maizatul Shima

    2016-11-01

    Effects of Cu:Zn ratio on the catalytic performance of synthesized SBA-15 supported Cu/ZnO-based (CZS) catalyst for the hydrogenation of CO2 to methanol was investigated in a fixed bed reactor. The physicochemical properties of the synthesized CZS catalyst in terms of textural properties, morphological and reducibility are presented. Methanol productivity was found to be influenced by the ratio of Cu and Zn in the catalyst formulation. Methanol selectivity of 92.1 % and CO2 conversion of 14.2 % was achieved over CZS catalyst with active metal ratio of 70 %Cu:30% Zn in CO2 hydrogenation reaction performed at 250°C, 2.25 MPa, and H2/CO2 ratio of 3.

  16. A Brief Review of Carbon Dioxide Hydrogenation to Methanol Over Copper and Iron Based Catalysts

    Directory of Open Access Journals (Sweden)

    Tursunov Obid

    2017-09-01

    Full Text Available Climate change and global warming have become a challenging issue affecting not only humanity but also flora and fauna due to an intense increase of CO2 emission in the atmosphere which has gradually led to amplification in the average global temperature. Hence, a number of mechanisms have been promoted to diminish the atmospheric commutation of carbon dioxide. One of the well-known techniques is Carbon Capture and Storage (CCS which mechanism is based on capture and storage vast quantities of CO2, as well as Carbon Capture and Utilization (CCU which mechanism is based on CO2 conversion to liquid fuels (e.g. methanol, hydrocarbons, dimethyl carbonate, propylene, dimethyl ether, ethylene, etc.. Particularly, methanol (CH3OH is a key feedstock for industrial chemicals, which further can be converted into high molecular alternative liquid fuels. In this regard, hydrogenation of CO2 is one of the promising, effectual and economic techniques for utilization of CO2 emission. Nevertheless, the reduction/activation of CO2 into useful liquid products is a scientifically challenging issue due to the complexities associated with its high stability. Thus, various catalysts have been applied to reduce the activation energy of the hydrogenation process and transform CO2 into value-added products. Thereby, this review article highlights the progress and the recent advances of research investigation in Cu and Fe-based catalytic conversion of CO2, reaction mechanisms, catalytic reactivity, and influence of operating parameters on product efficiency.

  17. Palladium on Nitrogen-Doped Mesoporous Carbon: A Bifunctional Catalyst for Formate-Based, Carbon-Neutral Hydrogen Storage.

    Science.gov (United States)

    Wang, Fanan; Xu, Jinming; Shao, Xianzhao; Su, Xiong; Huang, Yanqiang; Zhang, Tao

    2016-02-08

    The lack of safe, efficient, and economical hydrogen storage technologies is a hindrance to the realization of the hydrogen economy. Reported herein is a reversible formate-based carbon-neutral hydrogen storage system that is established over a novel catalyst comprising palladium nanoparticles supported on nitrogen-doped mesoporous carbon. The support was fabricated by a hard template method and nitridated under a flow of ammonia. Detailed analyses demonstrate that this bicarbonate/formate redox equilibrium is promoted by the cooperative role of the doped nitrogen functionalities and the well-dispersed, electron-enriched palladium nanoparticles. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Hydrogenation catalysts based on complexes of palladium(II) and polyvinylpyridines

    Energy Technology Data Exchange (ETDEWEB)

    Zharmagambetova, A.K.; Mukhamedzhanova, S.G.; Bekturov, E.A.; Saltykov, Yu.P.

    1992-05-20

    Recently methods for producing a new type of catalyst, grafted complexes have been developed. Polymers containing functional groups have been used quite successfully as a substrate in such catalysts. The refinement of the preparative method for metallopolymeric complexes (MPC) is of some importance. By varying the conditions of interaction between the polymers and the metal compounds the catalytic properties of MPC can be improved significantly. In this study the authors have looked at the effect of the preparative conditions for complexes of palladium(II) with poly-2-vinylpyridine (Pd-P2VP) on their catalytic activity in the hydrogenation of 2-propen-1-ol. 13 refs., 3 figs., 1 tab.

  19. Thermo-Catalytic Methane Decomposition for Hydrogen Production: Effect of Palladium Promoter on Ni-based Catalysts

    Directory of Open Access Journals (Sweden)

    Irene Lock Sow Mei

    2016-08-01

    Full Text Available Hydrogen production from the direct thermo-catalytic decomposition of methane is a promising alternative for clean fuel production. However, thermal decomposition of methane can hardly be of any practical and empirical interest in the industry unless highly efficient and effective catalysts, in terms of both catalytic activity and operational lifetime have been developed. In this study, the effect of palladium (Pd as a promoter onto Ni supported on alumina catalyst has been investigated by using co-precipitation technique. The introduction of Pd promotes better catalytic activity, operational lifetime and thermal stability of the catalyst. As expected, highest methane conversion was achieved at reaction temperature of 800 °C while the bimetallic catalyst (1 wt.% Ni -1wt.% Pd/Al2O3 gave the highest methane conversion of 70% over 15 min of time-on-stream (TOS. Interestingly, the introduction of Pd as promoter onto Ni-based catalyst also has a positive effect on the operational lifetime and thermal stability of the catalyst as the methane conversion has improved significantly over 240 min of TOS. Copyright © 2016 BCREC GROUP. All rights reserved Received: 21st January 2016; Revised: 6th February 2016; Accepted: 6th March 2016 How to Cite: Mei, I.L.S., Lock, S.S.M., Vo, D.V.N., Abdullah, B. (2016. Thermo-Catalytic Methane Decomposition for Hydrogen Production: Effect of Palladium Promoter on Ni-based Catalysts. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (2: 191-199 (doi:10.9767/bcrec.11.2.550.191-199 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.11.2.550.191-199

  20. Investigation of TiO2 based Mixed-metal Oxide Catalysts for the Production of Hydrogen

    Science.gov (United States)

    Luo, Si

    Abstract of the Dissertation. Investigation of TiO2 based Mixed-metal Oxide Catalysts for the Production of Hydrogen. by. Si Luo. Doctor of Philosophy. in. Chemistry. Stony Brook University. 2017. The environmental impacts of fossil fuel consumption and the resulting global warming have attracted increasing attention to technologies and fuels that are both sustainable and renewable in the 21st century. To date, hydrogen has been proposed as an encouraging candidate of the next generation of chemical fuels, which meets all demands for carbon free and efficient chemistries that could be produced from a variety of sources. However, despite tremendous efforts, there is a clear need to develop new catalysts for the production of hydrogen through catalytic processes that are sustainable, such as in the photocatalytic splitting of water (PCS: H2O → H2 + 0.5O2) and the water-gas shift process (WGS: CO + H2O → H2 + CO2). This thesis is primarily motivated by this challenge and has focused on the photochemical and thermal production of H2 by the employment of novel TiO2 based catalysts. TiO2 is one of the most widely studied photocatalysts in all history, due to its relatively high activity, robust stability, safety and low cost. In this thesis, several TiO2-based mixed metal oxide nano catalysts (CeOx-TiO2, Ru-TiO2, Ga-TiO2) have been synthesized with carefully controlled morphology/structure and with inclusion of co-catalysts (Pt). These novel materials were comprehensively characterized to better understand their morphology, crystal structure, and electronic properties in an attempt to unravel phenomena responsible for high catalytic performance for the production of H2 from H2O. We have discovered the importance of low-dimensional metal oxide and interfacial stabilized nano-scaled mixed metal oxides for H2 production, while learning how best to tune such structure to optimize both thermal and photochemical conversion. Optimized structure and/or composition have been

  1. Effect of Oxide Coating on Performance of Copper-Zinc Oxide-Based Catalyst for Methanol Synthesis via Hydrogenation of Carbon Dioxide

    Directory of Open Access Journals (Sweden)

    Tetsuo Umegaki

    2015-11-01

    Full Text Available The effect of oxide coating on the activity of a copper-zinc oxide–based catalyst for methanol synthesis via the hydrogenation of carbon dioxide was investigated. A commercial catalyst was coated with various oxides by a sol-gel method. The influence of the types of promoters used in the sol-gel reaction was investigated. Temperature-programmed reduction-thermogravimetric analysis revealed that the reduction peak assigned to the copper species in the oxide-coated catalysts prepared using ammonia shifts to lower temperatures than that of the pristine catalyst; in contrast, the reduction peak shifts to higher temperatures for the catalysts prepared using L(+-arginine. These observations indicated that the copper species were weakly bonded with the oxide and were easily reduced by using ammonia. The catalysts prepared using ammonia show higher CO2 conversion than the catalysts prepared using L(+-arginine. Among the catalysts prepared using ammonia, the silica-coated catalyst displayed a high activity at high temperatures, while the zirconia-coated catalyst and titania-coated catalyst had high activity at low temperatures. At high temperature the conversion over the silica-coated catalyst does not significantly change with reaction temperature, while the conversion over the zirconia-coated catalyst and titania-coated catalyst decreases with reaction time. From the results of FTIR, the durability depends on hydrophilicity of the oxides.

  2. Production Hydrogen And Nanocarbon Via Methane Decomposition Using Ni-Based Catalysts. Effect Of Acidity And Catalyst Diameter

    Directory of Open Access Journals (Sweden)

    Widodo Purwanto

    2010-10-01

    Full Text Available Objectives of this research are mainly to study impacts of acidity strength (by varying amount of precipitant and loading Al-Si and the effect of nickel particle size (by varying calcinations temperature on decomposition reaction performances. In this research, high-nickel-loaded catalyst is prepared with two methods. Ni-Cu/Al catalysts were prepared with co-precipitation method. While the Ni-Cu/Al-Si catalyst were prepared by combined co-precipitation and sol-gel method. The direct cracking of methane was performed in 8mm quartz fixed bed reactor at atmospheric pressure and 500-700°C. The main  results showed that the Al content of catalyst increases with the increasing amount of precipitant. The activity of catalyst increases with the increasing of catalyst's acidity to the best possible point, and then increasing of acidity will reduce the activity of catalyst. Ni-Cu/4Al and Ni-Cu/11Al deactivated in a  very short time hence produced fewer amount of nanocarbon, while Ni-Cu/15Al was active in a very  long period. The most effective catalyst is Ni-Cu/22Al, which produced the biggest amount of nanocarbon (4.15 g C/g catalyst. Ni catalyst diameter has significant effect on reaction performances mainly  methane conversion and product yield. A small Ni crystal size gave a high methane conversion, a fast deactivation and a low carbon yield. Large Ni particle  diameter yielded a slow decomposition and low methane conversion. The highest methane  conversion was produced by catalyst diameter of 4 nm and maximum yield of carbon of 4.08 g C/ g catalyst was achieved by 15.5 nm diameter of Ni catalyst.

  3. Mechanical alloying of a hydrogenation catalyst used for the remediation of contaminated compounds

    Science.gov (United States)

    Quinn, Jacqueline W. (Inventor); Clausen, Christian A. (Inventor); Geiger, Cherie L. (Inventor); Aitken, Brian S. (Inventor)

    2012-01-01

    A hydrogenation catalyst including a base material coated with a catalytic metal is made using mechanical milling techniques. The hydrogenation catalysts are used as an excellent catalyst for the dehalogenation of contaminated compounds and the remediation of other industrial compounds. Preferably, the hydrogenation catalyst is a bimetallic particle including zero-valent metal particles coated with a catalytic material. The mechanical milling technique is simpler and cheaper than previously used methods for producing hydrogenation catalysts.

  4. Production Hydrogen and Nanocarbon Via Methane Decomposition Using Ni-based Catalysts. Effect of Acidity and Catalyst Diameter

    OpenAIRE

    Widodo W. Purwanto; M Nasikin; E Saputra; Song, L.

    2005-01-01

    Objectives of this research are mainly to study impacts of acidity strength (by varying amount of precipitant and loadingAl-Si) and the effect of nickel particle size (by varying calcinations temperature) on decomposition reactionperformances. In this research, high-nickel-loaded catalyst is prepared with two methods. Ni-Cu/Al catalysts wereprepared with co-precipitation method. While the Ni-Cu/Al-Si catalyst were prepared by combined co-precipitation andsol-gel method. The direct cracking of...

  5. Reversible Hydrogenation of Carbon Dioxide to Formic Acid and Methanol: Lewis Acid Enhancement of Base Metal Catalysts.

    Science.gov (United States)

    Bernskoetter, Wesley H; Hazari, Nilay

    2017-04-18

    New and sustainable energy vectors are required as a consequence of the environmental issues associated with the continued use of fossil fuels. H 2 is a potential clean energy source, but as a result of problems associated with its storage and transport as a gas, chemical H 2 storage (CHS), which involves the dehydrogenation of small molecules, is an attractive alternative. In principle, formic acid (FA, 4.4 wt % H 2 ) and methanol (MeOH, 12.6 wt % H 2 ) can be obtained renewably and are excellent prospective liquid CHS materials. In addition, MeOH has considerable potential both as a direct replacement for gasoline and as a fuel cell input. The current commercial syntheses of FA and MeOH, however, use nonrenewable feedstocks and will not facilitate the use of these molecules for CHS. An appealing option for the sustainable synthesis of both FA and MeOH, which could be implemented on a large scale, is the direct metal catalyzed hydrogenation of CO 2 . Furthermore, given that CO 2 is a readily available, nontoxic and inexpensive source of carbon, it is expected that there will be economic and environmental benefits from using CO 2 as a feedstock. One strategy to facilitate both the dehydrogenation of FA and MeOH and the hydrogenation of CO 2 and H 2 to FA and MeOH is to utilize a homogeneous transition metal catalyst. In particular, the development of catalysts based on first row transition metals, which are cheaper, and more abundant than their precious metal counterparts, is desirable. In this Account, we describe recent advances in the development of iron and cobalt systems for the hydrogenation of CO 2 to FA and MeOH and the dehydrogenation of FA and MeOH and provide a brief comparison between precious metal and base metal systems. We highlight the different ligands that have been used to stabilize first row transition metal catalysts and discuss the use of additives to promote catalytic activity. In particular, the Account focuses on the crucial role that

  6. Salicylaldimine-based metal-organic framework enabling highly active olefin hydrogenation with iron and cobalt catalysts.

    Science.gov (United States)

    Manna, Kuntal; Zhang, Teng; Carboni, Michaël; Abney, Carter W; Lin, Wenbin

    2014-09-24

    A robust and porous Zr metal-organic framework, sal-MOF, of UiO topology was synthesized using a salicylaldimine (sal)-derived dicarboxylate bridging ligand. Postsynthetic metalation of sal-MOF with iron(II) or cobalt(II) chloride followed by treatment with NaBEt3H in THF resulted in Fe- and Co-functionalized MOFs (sal-M-MOF, M = Fe, Co) which are highly active solid catalysts for alkene hydrogenation. Impressively, sal-Fe-MOF displayed very high turnover numbers of up to 145000 and was recycled and reused more than 15 times. This work highlights the unique opportunity of developing MOF-based earth-abundant catalysts for sustainable chemical synthesis.

  7. Nickel-based electrodeposits as potential cathode catalysts for hydrogen production by microbial electrolysis

    Science.gov (United States)

    Mitov, M.; Chorbadzhiyska, E.; Nalbandian, L.; Hubenova, Y.

    2017-07-01

    The development of cost-effective cathodes, operating at neutral pH and ambient temperatures, is a crucial challenge for the practical application of microbial electrolysis cell (MEC) technology. In this study, NiW and NiMo co-deposits produced by electroplating on Ni-foam are explored as cathodes in MEC. The fabricated electrodes exhibit higher corrosion stability and enhanced electrocatalytic activity towards hydrogen evolution reaction in neutral electrolyte compared to the bare Ni-foam. NiW/Ni-foam electrodes possess six times higher intrinsic catalytic activity, estimated from data obtained by linear voltammetry and chronoamperometry. The newly developed electrodes are applied as cathodes in single-chamber membrane-free MEC reactors, inoculated with wastewater and activated sludge from a municipal wastewater treatment plant. Cathodic hydrogen recovery of 79% and 89% by using NiW and NiMo cathodes, respectively, is achieved at applied voltage of 0.6 V. The obtained results reveal potential for practical application of used catalysts in MEC.

  8. Liquefaction of kraft lignin by hydrocracking with simultaneous use of a novel dual acid-base catalyst and a hydrogenation catalyst.

    Science.gov (United States)

    Wang, Jindong; Li, Wenzhi; Wang, Huizhen; Ma, Qiaozhi; Li, Song; Chang, Hou-Min; Jameel, Hasan

    2017-11-01

    In this study, a novel catalyst, S 2 O 8 2- -KNO 3 /TiO 2 , which has active acidic and basic sites, was prepared and used in lignin hydrocracking with a co-catalyst, Ru/C. Ru/C is an efficient hydrogenation catalyst and S 2 O 8 2- -KNO 3 /TiO 2 is a dual catalyst, which could efficiently degrade lignin. This catalytic hydrogenation system can reduce solid products to less than 1%, while giving a high liquid product yield of 93%. Catalytic hydrocracking of kraft lignin at 320°C for 6h gave 93% liquid product with 0.5% solid product. Most of this liquid product was soluble in petroleum ether (60% of 93%), which is a clear liquid and comprises mainly of monomeric and dimeric degradation products. These results demonstrated that the combination of the two catalysts is an efficient catalyst for liquefaction of lignin, with little char formation (∼1%). This concept has the potential to produce valuable chemicals and fuels from lignin under moderate conditions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Catalytically Enhanced Hydrogen Sorption in Mg-MgH2 by Coupling Vanadium-Based Catalyst and Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Atikah Kadri

    2015-06-01

    Full Text Available Mg (MgH2-based composites, using carbon nanotubes (CNTs and pre-synthesized vanadium-based complex (VCat as the catalysts, were prepared by high-energy ball milling technique. The synergistic effect of coupling CNTs and VCat in MgH2 was observed for an ultra-fast absorption rate of 6.50 wt. % of hydrogen per minute and 6.50 wt. % of hydrogen release in 10 min at 200 °C and 300 °C, respectively. The temperature programmed desorption (TPD results reveal that coupling VCat and CNTs reduces both peak and onset temperatures by more than 60 °C and 114 °C, respectively. In addition, the presence of both VCat and CNTs reduces the enthalpy and entropy of desorption of about 7 kJ/mol H2 and 11 J/mol H2·K, respectively, as compared to those of the commercial MgH2, which ascribe to the decrease of desorption temperature. From the study of the effect of CNTs milling time, it is shown that partially destroyed CNTs (shorter milling time are better to enhance the hydrogen sorption performance.

  10. Hydrogenation of biofuels with formic acid over a palladium-based ternary catalyst with two types of active sites.

    Science.gov (United States)

    Wang, Liang; Zhang, Bingsen; Meng, Xiangju; Su, Dang Sheng; Xiao, Feng-Shou

    2014-06-01

    A composite catalyst including palladium nanoparticles on titania (TiO2) and on nitrogen-modified porous carbon (Pd/TiO2@N-C) is synthesized from palladium salts, tetrabutyl titanate, and chitosan. N2 sorption isotherms show that the catalyst has a high BET surface area (229 m(2)  g(-1)) and large porosity. XPS and TEM characterization of the catalyst shows that palladium species with different chemical states are well dispersed across the TiO2 and nitrogen-modified porous carbon, respectively. The Pd/TiO2@N-C catalyst is very active and shows excellent stability towards hydrogenation of vanillin to 2-methoxy-4-methylphenol using formic acid as hydrogen source. This activity can be attributed to a synergistic effect between the Pd/TiO2 (a catalyst for dehydrogenation of formic acid) and Pd/N-C (a catalyst for hydrogenation of vanillin) sites. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Efficient Hydrogen Storage and Production Using a Catalyst with an Imidazoline-Based, Proton-Responsive Ligand.

    Science.gov (United States)

    Wang, Lin; Onishi, Naoya; Murata, Kazuhisa; Hirose, Takuji; Muckerman, James T; Fujita, Etsuko; Himeda, Yuichiro

    2017-03-22

    A series of new imidazoline-based iridium complexes has been developed for hydrogenation of CO2 and dehydrogenation of formic acid. One of the proton-responsive complexes bearing two -OH groups at ortho and para positions on a coordinating pyridine ring (3 b) can catalyze efficiently the chemical fixation of CO2 and release H2 under mild conditions in aqueous media without using organic additives/solvents. Notably, hydrogenation of CO2 can be efficiently carried out under CO2 and H2 at atmospheric pressure in basic water by 3 b, achieving a turnover frequency of 106 h(-1) and a turnover number of 7280 at 25 °C, which are higher than ever reported. Moreover, highly efficient CO-free hydrogen production from formic acid in aqueous solution employing the same catalyst under mild conditions has been achieved, thus providing a promising potential H2 -storage system in water. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Semisynthetic and Biomolecular Hydrogen Evolution Catalysts.

    Science.gov (United States)

    Kandemir, Banu; Chakraborty, Saikat; Guo, Yixing; Bren, Kara L

    2016-01-19

    There has been great interest in the development of stable, inexpensive, efficient catalysts capable of reducing aqueous protons to hydrogen (H2), an alternative to fossil fuels. While synthetic H2 evolution catalysts have been in development for decades, recently there has been great progress in engineering biomolecular catalysts and assemblies of synthetic catalysts and biomolecules. In this Forum Article, progress in engineering proteins to catalyze H2 evolution from water is discussed. The artificial enzymes described include assemblies of synthetic catalysts and photosynthetic proteins, proteins with cofactors replaced with synthetic catalysts, and derivatives of electron-transfer proteins. In addition, a new catalyst consisting of a thermophilic cobalt-substituted cytochrome c is reported. As an electrocatalyst, the cobalt cytochrome shows nearly quantitative Faradaic efficiency and excellent longevity with a turnover number of >270000.

  13. Platinum on Carbon Nanofibers as Catalyst for Cinnamaldehyde Hydrogenation

    NARCIS (Netherlands)

    Plomp, A.J.

    2009-01-01

    The aim of the work described in this thesis was to investigate the role and nature of nanostructured carbon materials, oxygen surface groups and promoters on platinum-based catalysts for the selective hydrogenation of cinnamaldehyde. The selective hydrogenation of cinnamaldehyde to cinnamyl alcohol

  14. Nickel-based xerogel catalysts: Synthesis via fast sol-gel method and application in catalytic hydrogenation of p-nitrophenol to p-aminophenol

    Science.gov (United States)

    Feng, Jin; Wang, Qiang; Fan, Dongliang; Ma, Lirong; Jiang, Deli; Xie, Jimin; Zhu, Jianjun

    2016-09-01

    In order to investigate the roles of three-dimensional network structure and calcium on Ni catalysts, the Ni, Ni-Al2O3, Ni-Ca-Al2O3 xerogel catalysts were successfully synthesized via the fast sol-gel process and chemical reduction method. The crystal structure of three different catalysts was observed with X-ray powder diffraction (XRD). Transmission electron microscopy (TEM), scanning electron microscopy (SEM) and nitrogen adsorption-desorption were employed to investigate the role of network structure of xerogel catalysts and the size distribution of Ni nanoparticles. The catalyst composition was determined by inductively coupled plasma-optical emission spectrometry (ICP-OES) measurement and energy-dispersive X-ray spectroscopy (EDS). Temperature-programmed reduction (TPR) experiments were carried out to investigate the reducibility of nickel species and the interaction between nickel species and alumina. The catalytic hydrogenation of p-nitrophenol to p-aminophenol was investigated over the prepared nickel-based xerogel catalysts. The conversion of p-nitrophenol was monitored by UV spectrophotometry and high performance liquid chromatography (HPLC). The results show that the catalysts are highly selective for the conversion of p-nitrophenol to p-aminophenol and the order of catalytic activities of the catalysts is Ni < Ni-Al2O3 < Ni-Ca-Al2O3. The catalysts were recycled and were used to evaluate the reutilization.

  15. Synthesis and use of an asymmetric transfer hydrogenation catalyst based on iron(II) for the synthesis of enantioenriched alcohols and amines.

    Science.gov (United States)

    Zuo, Weiwei; Morris, Robert H

    2015-02-01

    The catalytic hydrogenation of prochiral ketones and imines is an advantageous approach to the synthesis of enantioenriched alcohols and amines, respectively, which are two classes of compounds that are highly prized in pharmaceutical, fragrance and flavoring chemistry. This hydrogenation reaction is generally carried out using ruthenium-based catalysts. Our group has developed an alternative synthetic route that is based on the environmentally friendlier iron-based catalysis. This protocol describes the three-part synthesis of trans-[amine(imine)diphosphine]chlorocarbonyliron(II) tetrafluoroborate templated by iron salts and starting from commercially available chemicals, which provides the precatalyst for the efficient asymmetric transfer hydrogenation of ketones and imines. The use of the enantiopure (S,S) catalyst to reduce prochiral ketones to the (R)-alcohol in good to excellent yields and enantioenrichment is also detailed, as well as the reduction to the amine in very high yield and enantiopurity of imines substituted at the nitrogen with the N-(diphenylphosphinoyl) group (-P(O)Ph2). Although the best ruthenium catalysts provide alcohols in higher enantiomeric excess (ee) than the iron complex catalyst used in this protocol, they do so on much longer time scales or at higher catalyst loadings. This protocol can be completed in 2 weeks.

  16. Steam reforming of ethanol for hydrogen production over Cu/Co-Mg-Al-based catalysts prepared by hydrotalcite route.

    Science.gov (United States)

    Homsi, Doris; Rached, Jihane Abou; Aouad, Samer; Gennequin, Cédric; Dahdah, Eliane; Estephane, Jane; Tidahy, Haingomalala Lucette; Aboukaïs, Antoine; Abi-Aad, Edmond

    2017-04-01

    The performances of different 5Cu/Co x Mg 6-x Al 2 (x = 0; 2; 4; 6) catalysts prepared by the wet impregnation method were investigated in the ethanol steam-reforming reaction (ESR) at 450 °C during 4 h under a steam/ethanol ratio of 3 (S/E = 3). The best catalyst among the prepared solids was 5Cu/Co 6 Al 2 as it showed a complete ethanol conversion and the highest hydrogen and carbon dioxide productivities. However, following 50 h of aging, the catalyst deactivated due to the formation of a high amount of carbonaceous products detected by differential scanning calorimetry/thermogravimetry. On the other hand, the 5Cu/Co 2 Mg 4 Al 2 catalyst showed a much lower quantity of coke deposition with no deactivation due to the basic character conferred by the magnesium oxide phase.

  17. The Effect of Copper Addition on the Activity and Stability of Iron-Based CO2 Hydrogenation Catalysts

    Directory of Open Access Journals (Sweden)

    Matthew J. Bradley

    2017-09-01

    Full Text Available Iron-based CO2 catalysts have shown promise as a viable route to the production of olefins from CO2 and H2 gas. However, these catalysts can suffer from low conversion and high methane selectivity, as well as being particularly vulnerable to water produced during the reaction. In an effort to improve both the activity and durability of iron-based catalysts on an alumina support, copper (10–30% has been added to the catalyst matrix. In this paper, the effects of copper addition on the catalyst activity and morphology are examined. The addition of 10% copper significantly increases the CO2 conversion, and decreases methane and carbon monoxide selectivity, without significantly altering the crystallinity and structure of the catalyst itself. The FeCu/K catalysts form an inverse spinel crystal phase that is independent of copper content and a metallic phase that increases in abundance with copper loading (>10% Cu. At higher loadings, copper separates from the iron oxide phase and produces metallic copper as shown by SEM-EDS. An addition of copper appears to increase the rate of the Fischer–Tropsch reaction step, as shown by modeling of the chemical kinetics and the inter- and intra-particle transport of mass and energy.

  18. Selective oxidation of sulfides to sulfoxides using 30% hydrogen peroxide catalyzed with a recoverable silica-based tungstate interphase catalyst.

    Science.gov (United States)

    Karimi, Babak; Ghoreishi-Nezhad, Maryam; Clark, James H

    2005-02-17

    Various types of aromatic and aliphatic sulfides are selectively oxidized to sulfoxides and sulfones in good to excellent yields using 30% H2O2 in the presence of catalytic amounts of a novel recoverable silica-based tungstate interphase catalyst at room temperature. The catalyst can be recovered and reused for at least eight reaction cycles under the described reaction conditions without considerable loss of reactivity. [reaction: see text

  19. Incorporation of Hydrogen-Bonding Functionalities into the Second Coordination Sphere of Iron-Based Water-Oxidation Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Hoffert, Wesley A.; Mock, Michael T.; Appel, Aaron M.; Yang, Jenny Y.

    2013-04-09

    Energy storage and conversion schemes based on environmentally benign chemical fuels will require the discovery of faster, cheaper, and more robust catalysts for the oxygen evolution reaction (OER). Although pendant bases have led to enhanced turnover frequencies with non-aqueous substrates, their effect on the catalytic behavior of molecular water oxidation catalysts has received little attention. Herein, the syntheses, structures, and catalytic activities of new iron complexes with pendant bases are reported. Of these, the complex [Fe(mepydz)4(CH3CN)2](OTf)2 (mepydz = N,N'-dimethyl-N,N'-bis(pyridazin-3-ylmethyl)ethane-1,2-diamine, OTf = trifluoromethanesulonate) (8(CH3CN)22+) is the most active catalyst. Initial turnover frequencies of 141 h-1 and 24 h-1 were measured using ceric ammonium nitrate at pH 0.7 and sodium periodate at pH 4.7, respectively. At pH 4.7, 8(CH3CN)22+ the initial turnover frequency is 70% faster than the structurally analogous complex without ancillary proton relays. These results demonstrate that the incorporation of pendant bases into molecular water oxidation catalysts is a synthetic principle that should be considered in the development of new OER catalysts. This work was supported by Laboratory Directed Research and Development program at Pacific Northwest National Laboratory (PNNL). PNNL is operated by Battelle for the US Department of Energy.

  20. Alkali promoted molybdenum (IV) sulfide based catalysts, development and characterization for alcohol synthesis from carbon monoxide and hydrogen

    Science.gov (United States)

    Molina, Belinda Delilah

    For more than a century transition metal sulfides (TMS) have been the anchor of hydro-processing fuels and upgrading bitumen and coal in refineries worldwide. As oil supplies dwindle and environmental laws become more stringent, there is a greater need for cleaner alternative fuels and/or synthetic fuels. The depletion of oil reserves and a rapidly increasing energy demand worldwide, together with the interest to reduce dependence on foreign oil makes alcohol production for fuels and chemicals via the Fischer Tropsch synthesis (FTS) very attractive. The original Fischer-Tropsch (FT) reaction is the heart of all gas-to-liquid technologies; it creates higher alcohols and hydrocarbons from CO/H2 using a metal catalyst. This research focuses on the development of alkali promoted MoS2-based catalysts to investigate an optimal synthesis for their assistance in the production of long chain alcohols (via FTS) for their use as synthetic transportation liquid fuels. Properties of catalytic material are strongly affected by every step of the preparation together with the quality of the raw materials. The choice of a laboratory method for preparing a given catalyst depends on the physical and chemical characteristics desired in the final composition. Characterization methods of K0.3/Cs0.3-MoS2 and K0.3 /Cs0.3-Co0.5MoS2 catalysts have been carried out through Scanning Electron Microscopy (SEM), BET porosity and surface analysis, Transmission Electron Microscopy (TEM) and X-Ray Diffraction (XRD). Various characterization methods have been deployed to correlate FTS products versus crystal and morphological properties of these heterogeneous catalysts. A lab scale gas to liquid system has been developed to evaluate its efficiency in testing FT catalysts for their production of alcohols.

  1. Dolomite-Derived Ni-Based Catalysts with Fe Modification for Hydrogen Production via Auto-Thermal Reforming of Acetic Acid

    Directory of Open Access Journals (Sweden)

    Xinyan Zhong

    2016-06-01

    Full Text Available Bio-oil can be obtained via fast pyrolysis of biomass, and typically contains acetic acid (~30 mass %. The acetic acid has often been tested as a model compound for hydrogen production via reforming bio-oil, in which catalysts are a key factor for stable hydrogen production. However, deactivation of catalysts by coking and oxidation hinders the application of the reforming process. Dolomite-derived Ni-based catalysts with Fe additive, MgNi0.2Ca0.8−xFexO2±δ (x = 0–0.8, were successfully synthesized by the hydrothermal synthesis method, and then tested in auto-thermal reforming (ATR of acetic acid (AC. The MgNi0.2Ca0.5Fe0.3O2±δ catalyst performed a stable reactivity in ATR: the conversion of AC reached 100%, and the H2 yield remained stable around 2.6 mol-H2/mol-AC. The catalysts were characterized by X-ray diffraction (XRD, N2 physisorption, X-ray photoelectron spectra (XPS, H2-temperature-programmed reduction (TPR, inductively coupled plasma- atomic emission spectroscopy (ICP-AES and Thermogravimetry (TG; the results show that a periclase-like solid solution of Mg(Ni,FeO and lime were formed via the precursors of dolomite and hydrotalcite, and then transformed into Fe-rich Ni-Fe alloy with basic support of MgO-CaO after reduction. The stable Ni0 spices with basic support can explain the stability and resistance to coking during ATR of AC.

  2. Nickel-based xerogel catalysts: Synthesis via fast sol-gel method and application in catalytic hydrogenation of p-nitrophenol to p-aminophenol

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Jin; Wang, Qiang; Fan, Dongliang; Ma, Lirong; Jiang, Deli; Xie, Jimin, E-mail: xiejm391@sohu.com; Zhu, Jianjun, E-mail: zhjj029@sina.com

    2016-09-30

    out to investigate the reducibility of nickel species and the interaction between nickel species and alumina. The catalytic hydrogenation of p-nitrophenol to p-aminophenol was investigated over the prepared nickel-based xerogel catalysts. The conversion of p-nitrophenol was monitored by UV spectrophotometry and high performance liquid chromatography (HPLC). The results show that the catalysts are highly selective for the conversion of p-nitrophenol to p-aminophenol and the order of catalytic activities of the catalysts is Ni < Ni-Al{sub 2}O{sub 3} < Ni-Ca-Al{sub 2}O{sub 3}. The catalysts were recycled and were used to evaluate the reutilization.

  3. Identification of non-precious metal alloy catalysts for selective hydrogenation of acetylene

    DEFF Research Database (Denmark)

    Studt, Felix; Abild-Pedersen, Frank; Bligaard, Thomas

    2008-01-01

    The removal of trace acetylene from ethylene is performed industrially by palladium hydrogenation catalysts ( often modified with silver) that avoid the hydrogenation of ethylene to ethane. In an effort to identify catalysts based on less expensive and more available metals, density functional...... calculations were performed that identified relations in heats of adsorption of hydrocarbon molecules and fragments on metal surfaces. This analysis not only verified the facility of known catalysts but identified nickel- zinc alloys as alternatives. Experimental studies demonstrated that these alloys...

  4. Hydrogen recombiner catalyst test supporting data

    Energy Technology Data Exchange (ETDEWEB)

    Britton, M.D.

    1995-01-19

    This is a data package supporting the Hydrogen Recombiner Catalyst Performance and Carbon Monoxide Sorption Capacity Test Report, WHC-SD-WM-TRP-211, Rev 0. This report contains 10 appendices which consist of the following: Mass spectrometer analysis reports: HRC samples 93-001 through 93-157; Gas spectrometry analysis reports: HRC samples 93-141 through 93-658; Mass spectrometer procedure PNL-MA-299 ALO-284; Alternate analytical method for ammonia and water vapor; Sample log sheets; Job Safety analysis; Certificate of mixture analysis for feed gases; Flow controller calibration check; Westinghouse Standards Laboratory report on Bois flow calibrator; and Sorption capacity test data, tables, and graphs.

  5. MODELING STYRENE HYDROGENATION KINETICS USING PALLADIUM CATALYSTS

    Directory of Open Access Journals (Sweden)

    G. T. Justino

    Full Text Available Abstract The high octane number of pyrolysis gasoline (PYGAS explains its insertion in the gasoline pool. However, its use is troublesome due to the presence of gum-forming chemicals which, in turn, can be removed via hydrogenation. The use of Langmuir-Hinshelwood kinetic models was evaluated for hydrogenation of styrene, a typical gum monomer, using Pd/9%Nb2O5-Al2O3 as catalyst. Kinetic models accounting for hydrogen dissociative and non-dissociative adsorption were considered. The availability of one or two kinds of catalytic sites was analyzed. Experiments were carried out in a semi-batch reactor at constant temperature and pressure in the absence of transport limitations. The conditions used in each experiment varied between 16 - 56 bar and 60 - 100 ºC for pressure and temperature, respectively. The kinetic models were evaluated using MATLAB and EMSO software. Models using adsorption of hydrogen and organic molecules on the same type of site fitted the data best.

  6. The use of plasma processing for catalyst and membrane synthesis and direct production of hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Brault, P.; Thomann, A.L.; Cormier, J.M.; Lefaucheux, Ph. [Orleans Univ., Groupe de Recheches sur l' Energetique des Milieux Ionises, UMR 6606, 45 (France)

    2000-07-01

    Plasma technologies are introduced in the field of hydrogen synthesis related to fuel cells. Two ways are described: plasma synthesis of catalysts and membranes for the production and separation of hydrogen and direct production of hydrogen based on atmospheric plasma assisted methane steam reforming.

  7. Antimicrobial activities of hydrogen peroxide and its activation by a novel heterogeneous Fenton's-like modified PAN catalyst

    National Research Council Canada - National Science Library

    Boateng, M K; Price, S L; Huddersman, K D; Walsh, S E

    2011-01-01

    .... The antimicrobial properties of an iron-based novel heterogeneous polyacrylonitrile catalyst in combination with hydrogen peroxide were examined against Escherichia coli, Pseudomonas aeruginosa...

  8. Noble metal-free hydrogen evolution catalysts for water splitting.

    Science.gov (United States)

    Zou, Xiaoxin; Zhang, Yu

    2015-08-07

    Sustainable hydrogen production is an essential prerequisite of a future hydrogen economy. Water electrolysis driven by renewable resource-derived electricity and direct solar-to-hydrogen conversion based on photochemical and photoelectrochemical water splitting are promising pathways for sustainable hydrogen production. All these techniques require, among many things, highly active noble metal-free hydrogen evolution catalysts to make the water splitting process more energy-efficient and economical. In this review, we highlight the recent research efforts toward the synthesis of noble metal-free electrocatalysts, especially at the nanoscale, and their catalytic properties for the hydrogen evolution reaction (HER). We review several important kinds of heterogeneous non-precious metal electrocatalysts, including metal sulfides, metal selenides, metal carbides, metal nitrides, metal phosphides, and heteroatom-doped nanocarbons. In the discussion, emphasis is given to the synthetic methods of these HER electrocatalysts, the strategies of performance improvement, and the structure/composition-catalytic activity relationship. We also summarize some important examples showing that non-Pt HER electrocatalysts could serve as efficient cocatalysts for promoting direct solar-to-hydrogen conversion in both photochemical and photoelectrochemical water splitting systems, when combined with suitable semiconductor photocatalysts.

  9. High pressure CO hydrogenation over bimetallic Pt-Co catalysts

    DEFF Research Database (Denmark)

    Christensen, Jakob Munkholt; Medford, Andrew James; Studt, Felix

    2014-01-01

    The potential of bimetallic Pt-Co catalysts for production of higher alcohols in high pressure CO hydrogenation has been assessed. Two catalysts (Pt3Co/SiO2 and PtCo/SiO2) were tested, and the existing literature on CO hydrogenation over Pt-Co catalysts was reviewed. It is found that the catalysts...... produce mainly methanol in the Pt-rich composition range andmainly hydrocarbons (and to a modest extent higher alcohols) in the Co-rich composition range. The transition between the two types of behavior occurs in a narrow composition range around a molar Pt:Co ratio of 1:1....

  10. Synthesis of liquid menthol by hydrogenation of dementholized peppermint oil over Ni catalysts

    Directory of Open Access Journals (Sweden)

    Debora L. Manuale

    2010-01-01

    Full Text Available Hydrogenation of (--menthone and (+-isomenthone was studied at 2.7 MPa and 100 ºC. The objective was to produce a liquid menthol mixture rich in (--menthol from dementholized peppermint oil. Ni-based catalysts were tested and compared for this reaction: a 6 and 12% Ni dispersed into a nonstoichiometric magnesium aluminate (Ni-Mg-Al with spinel structure; b Ni-Raney catalyst. Both types of catalysts were active for (--menthone and (+-isomenthone hydrogenation. Lower conversion but higher selectivity to (--menthol was obtained with Ni-Mg-Al catalysts. However, they rapidly lost their activity. Instead Ni-Raney catalysts kept its original activity even after several hydrogenation runs.

  11. Vapor phase hydrogenation of furfural over nickel mixed metal oxide catalysts derived from layered double hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    Sulmonetti, Taylor P.; Pang, Simon H.; Claure, Micaela Taborga; Lee, Sungsik; Cullen, David A.; Agrawal, Pradeep K.; Jones, Christopher W.

    2016-05-01

    The hydrogenation of furfural is investigated over various reduced nickel mixed metal oxides derived from layered double hydroxides (LDHs) containing Ni-Mg-Al and Ni-Co-Al. Upon reduction, relatively large Ni(0) domains develop in the Ni-Mg-Al catalysts, whereas in the Ni-Co-Al catalysts smaller metal particles of Ni(0) and Co(0), potentially as alloys, are formed, as evidenced by XAS, XPS, STEM and EELS. All the reduced Ni catalysts display similar selectivities towards major hydrogenation products (furfuryl alcohol and tetrahydrofurfuryl alcohol), though the side products varied with the catalyst composition. The 1.1Ni-0.8Co-Al catalyst showed the greatest activity per titrated site when compared to the other catalysts, with promising activity compared to related catalysts in the literature. The use of base metal catalysts for hydrogenation of furanic compounds may be a promising alternative to the well-studied precious metal catalysts for making biomass-derived chemicals if catalyst selectivity can be improved in future work by alloying or tuning metal-oxide support interactions.

  12. Hydrogenation of artemisinin to dihydroartemisinin over heterogeneous metal catalysts

    Science.gov (United States)

    Kristiani, Anis; Pertiwi, Ralentri; Adilina, Indri Badria

    2017-01-01

    A series of heterogeneous metal catalysts of Ni, Pd, and Pt, both of synthesized and commercial catalysts were used for hydrogenation of artemisinin to dihydroartemisinin. Their catalytic properties were determsined by Surface Area Analyzer and Thermogravimetry Analyzer. The catalytic properties in various reaction conditions in terms of temperature, pressure, reaction time and reactant/catalyst ratio were also studied. The results catalytic activity tests showed that synthesized catalysts of Ni/zeolite, Ni-Sn/zeolite, Ni/bentonite and Ni-Sn/bentonite were not able to produced dihydroartemisinin and deoxyartemisinin was mainly formed. Meanwhile, commercial catalysts of Ni skeletal, Pd/activated charcoal and Pt/activated charcoal yielded the desired dihydroartemisinin product. Ni skeletal commercial catalyst gave the best performance of hydrogenation artemisinin to dihydroartemisinin in room temperature and low H2 pressure.

  13. First-row transition metal hydrogenation and hydrosilylation catalysts

    Science.gov (United States)

    Trovitch, Ryan J.; Mukhopadhyay, Tufan K.; Pal, Raja; Levin, Hagit Ben-Daat; Porter, Tyler M.; Ghosh, Chandrani

    2017-07-18

    Transition metal compounds, and specifically transition metal compounds having a tetradentate and/or pentadentate supporting ligand are described, together with methods for the preparation thereof and the use of such compounds as hydrogenation and/or hydrosilylation catalysts.

  14. RuP{sub 2}-based catalysts with platinum-like activity and higher durability for the hydrogen evolution reaction at all pH values

    Energy Technology Data Exchange (ETDEWEB)

    Pu, Zonghua; Amiinu, Ibrahim Saana; Kou, Zongkui; Li, Wenqiang; Mu, Shichun [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology (China)

    2017-09-11

    Highly active, stable, and cheap Pt-free catalysts for the hydrogen evolution reaction (HER) are under increasing demand for future energy conversion systems. However, developing HER electrocatalysts with Pt-like activity that can function at all pH values still remains as a great challenge. Herein, based on our theoretical predictions, we design and synthesize a novel N,P dual-doped carbon-encapsulated ruthenium diphosphide (RuP{sub 2} rate at NPC) nanoparticle electrocatalyst for HER. Electrochemical tests reveal that, compared with the Pt/C catalyst, RuP{sub 2} rate at NPC not only has Pt-like HER activity with small overpotentials at 10 mA cm{sup -2} (38 mV in 0.5 m H{sub 2}SO{sub 4}, 57 mV in 1.0 m PBS and 52 mV in 1.0 m KOH), but demonstrates superior stability at all pH values, as well as 100 % Faradaic yields. Therefore, this work adds to the growing family of transition-metal phosphides/heteroatom-doped carbon heterostructures with advanced performance in HER. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Supported organometallic catalysts for hydrogenation and Olefin Polymerization

    Science.gov (United States)

    Marks, Tobin J.; Ahn, Hongsang

    2001-01-01

    Novel heterogeneous catalysts for the which hydrogenation of olefins and arenes with high conversion rates under ambient conditions and the polymerization of olefins have been developed. The catalysts are synthesized from Ziegler-type precatalysts by supporting them on sulfate-modified zirconia.

  16. Co-catalyst free Titanate Nanorods for improved Hydrogen ...

    Indian Academy of Sciences (India)

    Abstract. Harnessing solar energy for water splitting into hydrogen (H2) and oxygen (O2) gases in the pres- ence of semiconductor catalyst is one of the most promising and cleaner methods of chemical fuel (H2) pro- duction. Herein, we report a simplified method for the preparation of photo-active titanate nanorods catalyst.

  17. Hydrogenation of citral into its derivatives using heterogeneous catalyst

    Science.gov (United States)

    Sudiyarmanto, Hidayati, Luthfiana Nurul; Kristiani, Anis; Aulia, Fauzan

    2017-11-01

    Citral as known as a monoterpene can be found in plants and citrus fruits. The hydrogenation of citral into its derivatives become interesting area for scientist. This compound and its derivatives can be used for many application in pharmaceuticals and food areas. The development of heterogeneous catalysts become an important aspect in catalytic hydrogenation citral process. Nickel supported catalysts are well known as hydrogenation catalyst. These heterogeneous catalysts were tested their catalytic activity in hydrogenation of citral. The effect of various operation conditions, in term of feed concentration, catalyst loading, temperature, and reaction time were also studied. The liquid products produced were analyzed by using Gas Chromatography-Mass Spectroscopy (GC-MS). The result of catalytic activity tests showed nickel skeletal catalyst exhibits best catalytic activity in hydrogenation of citral. The optimum of operation condition was achieved in citral concentration 0.1 M with nickel skeletal catalyst loading of 10% (w/w) at 80 °C and 20 bar for 2 hours produced the highest conversion as of 64.20% and the dominant product resulted was citronellal as of 56.48%.

  18. Modifications for the improvement of catalyst materials for hydrogen evolution

    Directory of Open Access Journals (Sweden)

    DRAGAN SLAVKOV

    2006-02-01

    Full Text Available The structural and electrocatalytic characteristics of composite materials based on non-precious metals were studied. Precursors of metallic phase (Ni, Co or CoNi and oxide phase (TiO2 were grafted on a carbon substrate (Vulcan XC-72 by the sol-gel procedure and thermally treated at 250 ºC. Ni and CoNi crystals of 10–20 nm were produced, in contrast the Co and TiO2 were amorphous. The dissimilar electronic character of the components gives rise to a significant electrocatalytic activity for the hydrogen evolution reaction (HER, even in the basic series of prepared materials. Further improvement of the catalysts was achieved by modification of all three components. Hence, Mo was added into the metallic phase, TiO2 was converted into the crystalline form and multiwall carbon nanotubes (MWCNTs were used instead of carbon particles. The improvement, expressed in terms of the lowering the hydrogen evolution overpotential at 60 mA cm–2, was the most pronounced in the Ni-based systems grafted on MWCNTs (120 mV lower HER overpotential compared to 60 mV in case of Ni-based systems grafted on crystalline TiO2 (TiO2 prepared at 450 ºC and of Ni-based systems containing 25 at.% Mo. Nevertheless, even with the realized enhancement, of all the fested materials, the Co-based systems remained superior HER catalysts.

  19. Influence of Sulfuric Acid on the Performance of Ruthenium-based Catalysts in the Liquid-Phase Hydrogenation of Levulinic Acid to γ-Valerolactone

    NARCIS (Netherlands)

    Ftouni, Jamal; Genuino, Homer C.|info:eu-repo/dai/nl/371571685; Muñoz-murillo, Ara; Bruijnincx, Pieter C. A.|info:eu-repo/dai/nl/33799529X; Weckhuysen, Bert M.|info:eu-repo/dai/nl/285484397

    2017-01-01

    The presence of biogenic or process-derived impurities poses a major problem on the efficient catalytic hydrogenation of biomass-derived levulinic acid to γ-valerolactone; hence, studies on their influence on catalyst stability are now required. Herein, the influence of sulfuric acid as feed

  20. High hydrogen desorption properties of Mg-based nanocomposite at moderate temperatures: The effects of multiple catalysts in situ formed by adding nickel sulfides/graphene

    Science.gov (United States)

    Xie, Xiubo; Chen, Ming; Liu, Peng; Shang, Jiaxiang; Liu, Tong

    2017-12-01

    Nickel sulfides decorated reduced graphene oxide (rGO) has been produced by co-reducing Ni2+ and graphene oxide (GO), and is subsequently ball milled with Mg nanoparticles (NPs) produced by hydrogen plasma metal reaction (HPMR). The nickel sulfides of about 800 nm completely in situ change to MgS, Mg2Ni and Ni multiple catalysts after first hydrogenation/dehydrogenation process at 673 K. The Mg-5wt%NiS/rGO nanocomposite shows the highest hydrogen desorption kinetics and capacity properties, and the catalytic effect order of the additives is NiS/rGO, NiS and rGO. At 573 K, the Mg-NiS/rGO nanocomposite can quickly desorb 3.7 wt% H2 in 10 min and 4.5 wt% H2 in 60 min. The apparent hydrogen absorption and desorption activation energies of the Mg-5wt%NiS/rGO nanocomposite are decreased to 44.47 and 63.02 kJ mol-1, smaller than those of the Mg-5wt%rGO and Mg-5wt%NiS samples. The best hydrogen desorption properties of the Mg-5wt%NiS/rGO nanocomposite can be explained by the synergistic catalytic effects of the highly dispersed MgS, Mg2Ni and Ni catalysts on the rGO sheets, and the more nucleation sites between the catalysts, rGO sheets and Mg matrix.

  1. The selective hydrogenation of crotonaldehyde over bimetallic catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Schoeb, Ann M. [Iowa State Univ., Ames, IA (United States)

    1997-10-17

    The selective hydrogenation of crotonaldehyde has been investigated over a monometallic Pt/SiO2 catalyst and platinum bimetallic catalysts where the second metal was either silver, copper, or tin. The effects of addition of a second metal to the Pt/SiO2 system on the selectivity to crotyl alcohol were investigated. The Pt-Sn bimetallic catalysts were characterized by hydrogen chemisorption, 1H NMR and microcalorimetry. The Pt-Ag/SiO2 and Pt-Cu/SiO2 catalysts were characterized by hydrogen chemisorption. Pt-Sn/SiO2 catalysts selectively hydrogenated crotonaldehyde to crotyl alcohol and the method of preparation of these catalysts affected the selectivity. The most selective Pt-Sn/SiO2 catalysts for the hydrogenation of crotonaldehyde to crotyl alcohol were those in which the Sn precursor was dissolved in a HCl solution. Sn increased both the rate of formation of butyraldehyde and the rate of formation of crotyl alcohol. The Pt/SiO2, Pt-Ag/SiO2 and Pt-Cu/SiO2 catalysts produced only butyraldehyde. Initial heats of adsorption (~90 kJ/mol) measured using microcalorimetry were not affected by the presence of Sn on Pt. We can conclude that there is no through metal electronic interaction between Pt and Sn at least with respect to hydrogen surface bonds since the Pt and Pt-Sn at least with respect to hydrogen surface bonds since the Pt and Pt-Sn had similar initial heats of adsorption coupled with the invariance of the 1H NMR Knight shift.

  2. Fibrous Catalyst-Enhanced Acanthamoeba Disinfection by Hydrogen Peroxide.

    Science.gov (United States)

    Kilvington, Simon; Winterton, Lynn

    2017-11-01

    Hydrogen peroxide (H2O2) disinfection systems are contact-lens-patient problem solvers. The current one-step, criterion-standard version has been widely used since the mid-1980s, without any significant improvement. This work identifies a potential next-generation, one-step H2O2, not based on the solution formulation but rather on a case-based peroxide catalyst. One-step H2O2 systems are widely used for contact lens disinfection. However, antimicrobial efficacy can be limited because of the rapid neutralization of the peroxide from the catalytic component of the systems. We studied whether the addition of an iron-containing catalyst bound to a nonfunctional propylene:polyacryonitrile fabric matrix could enhance the antimicrobial efficacy of these one-step H2O2 systems. Bausch + Lomb PeroxiClear and AOSept Plus (both based on 3% H2O2 with a platinum-neutralizing disc) were the test systems. These were tested with and without the presence of the catalyst fabric using Acanthamoeba cysts as the challenge organism. After 6 hours' disinfection, the number of viable cysts was determined. In other studies, the experiments were also conducted with biofilm formed by Stenotrophomonas maltophilia and Elizabethkingia meningoseptica bacteria. Both control systems gave approximately 1-log10 kill of Acanthamoeba cysts compared with 3.0-log10 kill in the presence of the catalyst (P catalyst compared with ≥3.0-log10 kill when it was omitted. In 30 rounds' recurrent usage, the experiments, in which the AOSept Plus system was subjected to 30 rounds of H2O2 neutralization with or without the presence of catalytic fabric, showed no loss in enhanced biocidal efficacy of the material. The catalytic fabric was also shown to not retard or increase the rate of H2O2 neutralization. We have demonstrated the catalyst significantly increases the efficacy of one-step H2O2 disinfection systems using highly resistant Acanthamoeba cysts and bacterial biofilm. Incorporating the catalyst into the

  3. Asymmetric Transfer Hydrogenation of Ketones with Modified Grubbs Metathesis Catalysts : On the Way to a Tandem Process

    NARCIS (Netherlands)

    Renom-Carrasco, Marc; Gajewski, Piotr; Pignataro, Luca; de Vries, Johannes G.; Piarulli, Umberto; Gennari, Cesare; Lefort, Laurent

    2016-01-01

    Herein, we report the successful transformation of a 1(st) generation Grubbs metathesis catalyst into an asymmetric transfer hydrogenation (ATH) catalyst. Upon addition of a chiral amine ligand, an alcohol and a base, the 1(st) generation Hoveyda-Grubbs catalyst (HG-I) was found to promote the

  4. Hydrogen production via methane decomposition on Raney-type catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Figueiredo, J.L.; Orfao, J.J.M.; Cunha, A.F. [Laboratorio de Catalise e Materiais, Laboratorio Associado LSRE/LCM, Departamento de Engenharia Quimica, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal)

    2010-09-15

    The catalytic decomposition of methane into hydrogen and carbon was studied on La{sub 2}O{sub 3} doped Ni and Ni-Cu Raney-type catalysts. The activity and stability of the catalysts were assessed by comparing the experimental conversions with the calculated equilibrium conversions for each set of experimental conditions, and the maximum conversions with the conversions at the end of (at least) 5 h tests, respectively. Improved stability of La{sub 2}O{sub 3} doped catalysts was ascribed to an electronic promotion effect. There is an optimum load of the promoter, which provides for extended periods of stable catalyst operation. The carbon deposits consist of carbon nanofibers and multiwall carbon nanotubes. The La{sub 2}O{sub 3} doped Ni-Cu Raney-type catalysts presented in this work are remarkably efficient for the production of hydrogen by methane decomposition. (author)

  5. Hydrogenation of Tetralin over Supported Ni and Ir Catalysts

    Directory of Open Access Journals (Sweden)

    Dipali P. Upare

    2013-01-01

    Full Text Available Selective hydrogenation and ring opening (SRO of tetrahydronaphthalene (tetralin was studied over nickel and iridium supported catalysts in the context of the removal of polynuclear aromatics from diesel fuel. The tetralin hydrogenation was carried out in a fixed-bed reactor at 270°C, using H2 pressure of 30 bars, WHSV of 2.3 h−1, and H2/feed molar ratio of 40; the resultant products were analyzed by GC and GC-MS. The Ir/SiO2 catalyst gave 85% of tetralin conversion and 75.1% of decalin products selectivity whereas Ni/SiO2 catalyst showed an unprecedented high catalytic performance with 88.3% of tetralin conversion and 93% of decalin products selectivity. The catalysts were characterized by using different characterization techniques such as XRD, TPR, and HR-TEM to know the physicochemical properties as well as active sites in the catalysts.

  6. Hydrocarbon reforming catalysts and new reactor designs for compact hydrogen generators

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, A.; Schwab, E.; Urtel, H. [BASF SE, Ludwigshafen (Germany); Farrauto, R. [BASF Catalysts LLC, Iselin, NJ (United States)

    2010-12-30

    A hydrogen based future energy scenario will use fuel cells for the conversion of chemically stored energy into electricity. Depending upon the type of fuel cell, different specifications will apply for the feedstock which is converted in the cell, ranging from very clean hydrogen for PEM-FC's to desulfurized methane for SOFC and MCFC technology. For the foreseeable future, hydrogen will be supplied by conventional reforming, however operated in compact and dynamic reformer designs. This requires that known catalyst formulations are offered in specific geometries, giving flexibility for novel reactor design options. These specific geometries can be special tablet shapes as well as monolith structures. Finally, also nonhydrocarbon feedstock might be used in special applications, e.g. bio-based methanol and ethanol. BASF offers catalysts for the full process chain starting from feedstock desulfurization via reforming, high temperature shift, low temperature shift to CO fine polishing either via selective oxidation or selective methanation. Depending upon the customer's design, most stages can be served either with precious metal based monolith solutions or base metal tablet solutions. For the former, we have taken the automobile catalyst monolith support and extended its application to the fuel cell hydrogen generation. Washcoats of precious metal supported catalysts can for example be deposited on ceramic monoliths and/or metal heat exchangers for efficient generation of hydrogen. Major advantages are high through puts due to more efficient heat transfer for catalysts on metal heat exchangers, lower pressure drop with greater catalyst mechanical and thermal stability compared to particulate catalysts. Base metal tablet catalysts on the other hand can have intrinsic cost advantages, larger fractions of the reactor can be filled with active mass, and if produced in unconventional shape, again novel reactor designs are made possible. Finally, if it comes to

  7. Catalysts based on platinum–tin and platinum–gallium in close contact for the selective hydrogenation of cinnamaldehyde

    NARCIS (Netherlands)

    Plomp, A.J.|info:eu-repo/dai/nl/304837598; van Asten, D.M.P.; van der Eerden, A.M.J.|info:eu-repo/dai/nl/304840483; Mäki-Arvela, P.; Murzin, D.Y.; de Jong, K.P.|info:eu-repo/dai/nl/06885580X; Bitter, J.H.|info:eu-repo/dai/nl/160581435

    2009-01-01

    Bimetallic platinum–tin and platinum–gallium catalysts supported on carbon nanofibers (CNF) were prepared via reductive deposition precipitation and impregnation. Detailed EXAFS, TEM-EDX and XPS studies showed that reductive deposition precipitation resulted in a close contact of tin with platinum.

  8. Sulfur tolerant zeolite supported platinum catalysts for aromatics hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Bergem, Haakon

    1997-12-31

    The increased demand for transportation fuels at the expence of heavier fuel oil has forced the refinery industry to expand their conversion capacity with hydrotreating as one of the key processes. A shift towards more diesel powered vehicles along with tightening fuel regulations demanding cleaner fuels has lead to increasing interest in catalytic processes for the manufacturing of such environmentally acceptable fuels. This provides the motivation for this thesis. Its main objective was to study possible catalysts active for desulfurization, hydrogenation, and ring-opening of aromatics all in the presence of sulfur. A close examination of the physical properties and kinetical behaviour of the chosen catalysts has been performed. A high pressure reactor setup was designed and built for activity measurements. Zeolite supported platinum catalysts were prepared and both the metal and acid functions were characterized utilizing various experimental techniques. Hydrogenation of toluene was used as a model reaction and the effect of sulfur adsorption on the activity and kinetic behaviour of the catalysts was investigated. The catalyst samples showed hydrogenation activities comparable to a commercial Pt/Al2O3 catalyst. There were no clear differences in the effect of the various sulfur compounds studied. Platinum supported on zeolite Y gave considerably more sulfur tolerant catalysts compared to Al2O3 as support. 155 refs., 58 figs., 36 tabs.

  9. Influence of hydrogen treatment on SCR catalysts

    DEFF Research Database (Denmark)

    Due-Hansen, Johannes

    reduction (SCR) process, i.e. the catalytic removal of NOx from the flue gas. A series of experiments was conducted to reveal the impact on the NO SCR activity of a industrial DeNOX catalyst (3%V2O5-7%WO3/TiO2) by treatment of H2. Standard conditions were treatment of the SCR catalyst for 60 min with three...

  10. Evidence that imidazolium-based ionic ligands can be metal(0)/nanocluster catalyst poisons in at least the test case of iridium(0)-catalyzed acetone hydrogenation.

    Science.gov (United States)

    Ott, Lisa Starkey; Campbell, Sarah; Seddon, Kenneth R; Finke, Richard G

    2007-11-26

    This study begins with the question of whether ionic liquids (ILs), such as 1-butyl-3-methylimidazolium hexafluorophosphate, [bmim][PF6], can be catalyst poisons for transition-metal catalysts rather than a preferred stabilizing media as typically assumed in the literature. The test case of acetone (propanone) hydrogenation is picked for two reasons: (i) acetone hydrogenation is important for its applications in heat pumps, H2 storage schemes, and fuel cells and for the commercial value of the resultant product, propan-2-ol, and (ii) two recent, independent studies have reported putative Ir(0)n nanocluster-catalyzed hydrogenations of acetone beginning in each case with the identical precursor, [{(COD)IrCl}2] (where COD=1,5-cyclooctadiene) (1). A close comparison of the results of those two literature studies and their related, but different, experimental conditions (vide infra) suggests the hypothesis that the IL is actually a catalyst poison. Indeed, the investigations herein (i) find that 1.0 equiv of added IL, [bmim][PF6], completely inhibits the formation of Ir(0)n nanoclusters under conditions 1 in Table 1 in the main text (namely, 3.6 mM precatalyst 1, 22 degrees C, and 2.76 bar H2) and (ii) demonstrate that 0.1 and 1.0 equivs of this same IL, [bmim][PF6], poisons 74 and 90%, respectively, of the acetone hydrogenation activity of premade, previously catalytically active nanoclusters. The above results in turn compelled a reinvestigation of the claim that Ir(0)n nanoclusters are the catalyst in what was reported as a colloidal suspension prepared under conditions 2 in Table 1 of the main text (namely, 52 mM precursor 1, 92 equiv of IL, 75 degrees C, and 4.05 bar of H2). We further (iii) find that the colloidal suspension prepared under conditions 2 is a mixture of unreacted precursor, 1, some nanoclusters, and isolable bulk metal, and we also (iv) find, somewhat surprisingly, in light of the IL-poisoning results found under conditions 1, that the Ir(0

  11. The application of inelastic neutron scattering to explore the significance of a magnetic transition in an iron based Fischer-Tropsch catalyst that is active for the hydrogenation of CO

    Science.gov (United States)

    Warringham, Robbie; McFarlane, Andrew R.; MacLaren, Donald A.; Webb, Paul B.; Tooze, Robert P.; Taylor, Jon; Ewings, Russell A.; Parker, Stewart F.; Lennon, David

    2015-11-01

    An iron based Fischer-Tropsch synthesis catalyst is evaluated using CO hydrogenation at ambient pressure as a test reaction and is characterised by a combination of inelastic neutron scattering (INS), powder X-ray diffraction, temperature-programmed oxidation, Raman scattering, and transmission electron microscopy. The INS spectrum of the as-prepared bulk iron oxide pre-catalyst (hematite, α-Fe2O3) is distinguished by a relatively intense band at 810 cm-1, which has previously been tentatively assigned as a magnon (spinon) feature. An analysis of the neutron scattering intensity of this band as a function of momentum transfer unambiguously confirms this assignment. Post-reaction, the spinon feature disappears and the INS spectrum is characterised by the presence of a hydrocarbonaceous overlayer. A role for the application of INS in magnetic characterisation of iron based FTS catalysts is briefly considered.

  12. The application of inelastic neutron scattering to explore the significance of a magnetic transition in an iron based Fischer-Tropsch catalyst that is active for the hydrogenation of CO

    Energy Technology Data Exchange (ETDEWEB)

    Warringham, Robbie; McFarlane, Andrew R.; Lennon, David, E-mail: David.Lennon@Glasgow.ac.uk [School of Chemistry, University of Glasgow, Joseph Black Building, Glasgow, Scotland G12 8QQ (United Kingdom); MacLaren, Donald A. [School of Physics and Astronomy, University of Glasgow, The Kelvin Building, Glasgow, Scotland G12 8QQ (United Kingdom); Webb, Paul B.; Tooze, Robert P. [Sasol Technology UK Ltd., Purdie Building, North Haugh, St Andrews, Fife KY16 9ST (United Kingdom); Taylor, Jon; Ewings, Russell A.; Parker, Stewart F. [ISIS Facility, STFC Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX (United Kingdom)

    2015-11-07

    An iron based Fischer-Tropsch synthesis catalyst is evaluated using CO hydrogenation at ambient pressure as a test reaction and is characterised by a combination of inelastic neutron scattering (INS), powder X-ray diffraction, temperature-programmed oxidation, Raman scattering, and transmission electron microscopy. The INS spectrum of the as-prepared bulk iron oxide pre-catalyst (hematite, α-Fe{sub 2}O{sub 3}) is distinguished by a relatively intense band at 810 cm{sup −1}, which has previously been tentatively assigned as a magnon (spinon) feature. An analysis of the neutron scattering intensity of this band as a function of momentum transfer unambiguously confirms this assignment. Post-reaction, the spinon feature disappears and the INS spectrum is characterised by the presence of a hydrocarbonaceous overlayer. A role for the application of INS in magnetic characterisation of iron based FTS catalysts is briefly considered.

  13. Hydrogen production by dry reforming of methane with carbon dioxide in one-dimensional nickel-based catalysts; Produccion de hidrogeno mediante el reformado seco de metano con dioxido de carbono en catalizadores unidimensionales a base de niquel

    Energy Technology Data Exchange (ETDEWEB)

    Lopez U, A. C.

    2016-07-01

    The main objective of this thesis is development of nickel catalysts supported over 1D matrix of cerium oxide, to be used in dry reforming methane reaction with carbon dioxide for hydrogen production. The catalysts were characterized by: Temperature Programmed Reduction (TPR), Scanning Electronic Microscopy (Sem), Surface Area (Bet method) an X Ray Diffraction (XRD). The TPR technique allowed to define reduction temperature of the active phase in the catalyst, Sem technique showed that the CeO{sub 2} matrix had a nano rod morphology. XRD allowed to identify the crystalline phases of the catalysts. Finally, the catalysts were tested in the dry reforming methane reaction, high catalytic activity and hydrogen production were performed at 700 degrees Celsius and the catalyst with 30 wt.% of nickel. (Author)

  14. Platinum Group Metal-free Catalysts for Hydrogen Evolution Reaction in Microbial Electrolysis Cells.

    Science.gov (United States)

    Yuan, Heyang; He, Zhen

    2017-07-01

    Hydrogen gas is a green energy carrier with great environmental benefits. Microbial electrolysis cells (MECs) can convert low-grade organic matter to hydrogen gas with low energy consumption and have gained a growing interest in the past decade. Cathode catalysts for the hydrogen evolution reaction (HER) present a major challenge for the development and future applications of MECs. An ideal cathode catalyst should be catalytically active, simple to synthesize, durable in a complex environment, and cost-effective. A variety of noble-metal free catalysts have been developed and investigated for HER in MECs, including Nickel and its alloys, MoS 2 , carbon-based catalysts and biocatalysts. MECs in turn can serve as a research platform to study the durability of the HER catalysts. This personal account has reviewed, analyzed, and discussed those catalysts with an emphasis on synthesis and modification, system performance and potential for practical applications. It is expected to provide insights into the development of HER catalysts towards MEC applications. © 2017 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Reducible oxide based catalysts

    Science.gov (United States)

    Thompson, Levi T.; Kim, Chang Hwan; Bej, Shyamal K.

    2010-04-06

    A catalyst is disclosed herein. The catalyst includes a reducible oxide support and at least one noble metal fixed on the reducible oxide support. The noble metal(s) is loaded on the support at a substantially constant temperature and pH.

  16. Chemical nature of coal hydrogenation oils. I - The effect of catalysts

    Science.gov (United States)

    Kershaw, J. R.; Barrass, G.; Gray, D.

    1980-05-01

    Hydrogenation of the same coal was carried out with no catalyst and with 1, 5, 10 and 15% stannous, zinc and ferrous chloride catalysts. The oils (hexane soluble portion) were fractionated by silica gel chromatography and by extraction with acid and base. The oils and fractions derived from them were investigated by C-13- and H-1-nuclear magnetic resonance, infrared, ultraviolet, fluorescence and phosphorescence spectroscopy. Increasing the amount of catalyst used decreased the percentage of polar compounds in the oil while the gross hydrocarbon structure showed little change with catalyst concentration. The decrease in the percentage of polar compounds in the oil results in a reduction in the viscosity of the oil due to decreased hydrogen bonding, which was shown by infrared and nuclear magnetic resonance studies.

  17. Co-catalyst free Titanate Nanorods for improved Hydrogen ...

    Indian Academy of Sciences (India)

    Harnessing solar energy for water splitting into hydrogen (H2) and oxygen (O2) gases in the presence of semiconductor catalyst is one of the most promising and cleaner ... Laboratory, Department of Materials Science and Nanotechnology, Yogi Vemana University, Vemanapuram, Kadapa 516 003, Andhra Pradesh, India ...

  18. Imaging hydrogen oxidation activity of catalyst-coated perfluoro ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 121; Issue 5. Imaging hydrogen oxidation activity of catalyst-coated perfluoro sulfonic acid-polymer electrolyte membranes using Scanning Electrochemical Microscopy. Meera Parthasarathy Vijayamohanan K Pillai. Volume 121 Issue 5 September 2009 pp 719-725 ...

  19. Solar-Driven Hydrogen Peroxide Production Using Polymer-Supported Carbon Dots as Heterogeneous Catalyst

    Science.gov (United States)

    Gogoi, Satyabrat; Karak, Niranjan

    2017-10-01

    Safe, sustainable, and green production of hydrogen peroxide is an exciting proposition due to the role of hydrogen peroxide as a green oxidant and energy carrier for fuel cells. The current work reports the development of carbon dot-impregnated waterborne hyperbranched polyurethane as a heterogeneous photo-catalyst for solar-driven production of hydrogen peroxide. The results reveal that the carbon dots possess a suitable band-gap of 2.98 eV, which facilitates effective splitting of both water and ethanol under solar irradiation. Inclusion of the carbon dots within the eco-friendly polymeric material ensures their catalytic activity and also provides a facile route for easy catalyst separation, especially from a solubilizing medium. The overall process was performed in accordance with the principles of green chemistry using bio-based precursors and aqueous medium. This work highlights the potential of carbon dots as an effective photo-catalyst.

  20. Perlite as a potential support for nickel catalyst in the process of sunflower oil hydrogenation

    Science.gov (United States)

    Radonjić, V.; Krstić, J.; Lončarević, D.; Jovanović, D.; Vukelić, N.; Stanković, M.; Nikolova, D.; Gabrovska, M.

    2015-12-01

    Investigation was conducted in order to elucidate the possibility of using perlite as support for preparation of nickel based precursor catalyst, potentially applicable in vegetable oil hydrogenation process. On three differently prepared expanded perlite, nickel catalyst precursors with identical Ni/SiO2 = 1.1 and Ni/Mg = 10/1 ratios were synthesized by precipitation-deposition method. Different techniques, SEM micrography, He-pycnometry, calcimetry, Hg-porosimetry, N2-physisorption, H2-chemisorption and temperature programmed reduction, were used for characterization of obtained samples. Determining the precursor texture, morphology and reducibility shows a successfully deposited nickel phase on perlite support with promising properties for vegetable oil hydrogenation. Chosen precursor was reduced and passivated in paraffin oil and the obtained catalyst showed significant catalytic activity in the test of sunflower oil hydrogenation.

  1. High Electrocatalytic Hydrogen Evolution Activity of an Anomalous Ruthenium Catalyst.

    Science.gov (United States)

    Zheng, Yao; Jiao, Yan; Zhu, Yihan; Li, Lu Hua; Han, Yu; Chen, Ying; Jaroniec, Mietek; Qiao, Shi-Zhang

    2016-12-14

    Hydrogen evolution reaction (HER) is a critical process due to its fundamental role in electrocatalysis. Practically, the development of high-performance electrocatalysts for HER in alkaline media is of great importance for the conversion of renewable energy to hydrogen fuel via photoelectrochemical water splitting. However, both mechanistic exploration and materials development for HER under alkaline conditions are very limited. Precious Pt metal, which still serves as the state-of-the-art catalyst for HER, is unable to guarantee a sustainable hydrogen supply. Here we report an anomalously structured Ru catalyst that shows 2.5 times higher hydrogen generation rate than Pt and is among the most active HER electrocatalysts yet reported in alkaline solutions. The identification of new face-centered cubic crystallographic structure of Ru nanoparticles was investigated by high-resolution transmission electron microscopy imaging, and its formation mechanism was revealed by spectroscopic characterization and theoretical analysis. For the first time, it is found that the Ru nanocatalyst showed a pronounced effect of the crystal structure on the electrocatalytic activity tested under different conditions. The combination of electrochemical reaction rate measurements and density functional theory computation shows that the high activity of anomalous Ru catalyst in alkaline solution originates from its suitable adsorption energies to some key reaction intermediates and reaction kinetics in the HER process.

  2. High Electrocatalytic Hydrogen Evolution Activity of an Anomalous Ruthenium Catalyst

    KAUST Repository

    Zheng, Yao

    2016-11-28

    Hydrogen evolution reaction (HER) is a critical process due to its fundamental role in electrocatalysis. Practically, the development of high-performance electrocatalysts for HER in alkaline media is of great importance for the conversion of renewable energy to hydrogen fuel via photoelectrochemical water splitting. However, both mechanistic exploration and materials development for HER under alkaline conditions are very limited. Precious Pt metal, which still serves as the state-of-the-art catalyst for HER, is unable to guarantee a sustainable hydrogen supply. Here we report an anomalously structured Ru catalyst that shows 2.5 times higher hydrogen generation rate than Pt and is among the most active HER electrocatalysts yet reported in alkaline solutions. The identification of new face-centered cubic crystallographic structure of Ru nanoparticles was investigated by high-resolution transmission electron microscopy imaging, and its formation mechanism was revealed by spectroscopic characterization and theoretical analysis. For the first time, it is found that the Ru nanocatalyst showed a pronounced effect of the crystal structure on the electrocatalytic activity tested under different conditions. The combination of electrochemical reaction rate measurements and density functional theory computation shows that the high activity of anomalous Ru catalyst in alkaline solution originates from its suitable adsorption energies to some key reaction intermediates and reaction kinetics in the HER process.

  3. Gold Supported on Graphene Oxide: An Active and Selective Catalyst for Phenylacetylene Hydrogenations at Low Temperatures

    DEFF Research Database (Denmark)

    Shao, Lidong; Huang, Xing; Teschner, Detre

    2014-01-01

    A constraint to industrial implementation of gold-catalyzed alkyne hydrogenation is that the catalytic activity was always inferior to those of other noble metals. In this work, gold was supported on graphene oxide (Au/GO) and used in a hydrogenation application. A 99% selectivity toward styrene...... with a 99% conversion in the hydrogenation of phenylacetylene was obtained at 60 °C, which is 100 to 200 °C lower than optimal temperatures in most previous reports on Au catalysts. A series of gold- and palladium-based reference catalysts were tested under the same conditions for phenylacetylene...... hydrogenation, and the performance of Au/GO was substantiated by studying the role of functionalized GO in governing the geometrical structure and thermal stability of supported Au nanoparticles under reaction conditions....

  4. Photoresist removal process by hydrogen radicals generated by W catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Takata, M. [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, 560-8531 (Japan)], E-mail: takata@nano.ee.es.osaka-u.ac.jp; Ogushi, K.; Yuba, Y.; Akasaka, Y. [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, 560-8531 (Japan); Tomioka, K.; Soda, E.; Kobayashi, N. [Semiconductor Leading Edge Technologies Inc., 16-1 Onogawa Tsukuba, Ibaraki, 305-8569 (Japan)

    2008-01-15

    Hydrogen radical process for photoresist removal by use of hot W catalyst has been investigated for a possible application to advanced Cu/low-k dielectric interconnects in LSI. It is found that etching rates of resists depend critically on sample temperature (T{sub s}) and are higher than 1 {mu}m/min at the optimized condition. H radical irradiation effects on porous methylsilsesquioxane (p-MSQ) have been studied from measurements of k value and capacitance of the advanced interconnect test sample. No radical process is observed to induce the increase in k value of p-MSQ films. These results suggest that the hydrogen radical process for resist removal with W catalyst is promising for production of advanced interconnects.

  5. Pd/MgO: Catalyst characterization and phenol hydrogenation activity

    Energy Technology Data Exchange (ETDEWEB)

    Claus, P.; Berndt, H.; Mohr, C.; Radnik, J.; Shin, E.J.; Keane, M.A.

    2000-05-15

    The gas-phase hydrogenation of phenol has been studied over a 1% w/w Pd/MgO catalyst prepared by impregnation of MgO with (NH{sub 4}){sub 2}PdCl{sub 6}. The catalyst precursor was activated by precalcination in air at 473 K followed by reduction in hydrogen at 573 K. Temperature-programmed reduction/desorption has revealed the presence of ammonium carbonate and/or ammonium hydrogen carbonate on the active surface in addition to a metallic palladium component. Whereas the latter was not detectable by X-ray diffraction due to the high metal dispersion, transmission electron microscopy revealed that the mean palladium particle diameter is 1.3 {+-} 0.2 nm, which corresponds to a palladium dispersion of D{sub Pd} = 71%. Impregnation followed by calcination is shown to transform MgO to Mg(OH){sub 2} while the additional reduction step generates a surface phase that is composed of both needle-like Periclase MgO and Mg(OH){sub 2}. X-ray photoelectron spectrometric analyses of the activated catalyst has established the presence of zero-valent palladium which appears to be electron rich as a result of metal-support interaction; a degree of palladium charging is also evident as well as residual surface chlorine. The effects on fractional phenol conversion and reaction selectivity of varying such process variables as reaction time, temperature, and phenol molar feed rate are considered and the possibility of thermodynamic limitations is addressed. Hydrogenation was observed to proceed in a stepwise fashion with cyclohexanone as the partially hydrogenated product and cyclohexanol as the fully hydrogenated product. The catalyst delivered a 96% selectivity with respect to cyclohexanone production at 423 K but the cyclohexanone yield decreased at higher temperatures as conversion declined and cyclohexanol was increasingly preferred. Conversion and selectivity were both stable with prolonged catalyst use, i.e., time on stream in excess of 55 h.

  6. A novel liquid organic hydrogen carrier system based on catalytic peptide formation and hydrogenation.

    Science.gov (United States)

    Hu, Peng; Fogler, Eran; Diskin-Posner, Yael; Iron, Mark A; Milstein, David

    2015-04-17

    Hydrogen is an efficient green fuel, but its low energy density when stored under high pressure or cryogenically, and safety issues, presents significant disadvantages; hence finding efficient and safe hydrogen carriers is a major challenge. Of special interest are liquid organic hydrogen carriers (LOHCs), which can be readily loaded and unloaded with considerable amounts of hydrogen. However, disadvantages include high hydrogen pressure requirements, high reaction temperatures for both hydrogenation and dehydrogenation steps, which require different catalysts, and high LOHC cost. Here we present a readily reversible LOHC system based on catalytic peptide formation and hydrogenation, using an inexpensive, safe and abundant organic compound with high potential capacity to store and release hydrogen, applying the same catalyst for loading and unloading hydrogen under relatively mild conditions. Mechanistic insight of the catalytic reaction is provided. We believe that these findings may lead to the development of an inexpensive, safe and clean liquid hydrogen carrier system.

  7. Bioinspired molecular co-catalysts bonded to a silicon photocathode for solar hydrogen evolution

    DEFF Research Database (Denmark)

    Hou, Yidong; Abrams, Billie L.; Vesborg, Peter Christian Kjærgaard

    2011-01-01

    The production of fuels from sunlight represents one of the main challenges in the development of a sustainable energy system. Hydrogen is the simplest fuel to produce and although platinum and other noble metals are efficient catalysts for photoelectrochemical hydrogen evolution, earth-abundant ......The production of fuels from sunlight represents one of the main challenges in the development of a sustainable energy system. Hydrogen is the simplest fuel to produce and although platinum and other noble metals are efficient catalysts for photoelectrochemical hydrogen evolution, earth......-abundant alternatives are needed for large-scale use. We show that bioinspired molecular clusters based on molybdenum and sulphur evolve hydrogen at rates comparable to that of platinum. The incomplete cubane-like clusters (Mo3S 4) efficiently catalyse the evolution of hydrogen when coupled to a p-type Si semiconductor...... that harvests red photons in the solar spectrum. The current densities at the reversible potential match the requirement of a photoelectrochemical hydrogen production system with a solar-to-hydrogen efficiency in excess of 10% (ref. 16). The experimental observations are supported by density functional theory...

  8. Dealloyed Ruthenium Film Catalysts for Hydrogen Generation from Chemical Hydrides

    Directory of Open Access Journals (Sweden)

    Ramis B. Serin

    2017-07-01

    Full Text Available Thin-film ruthenium (Ru and copper (Cu binary alloys have been prepared on a Teflon™ backing layer by cosputtering of the precious and nonprecious metals, respectively. Alloys were then selectively dealloyed by sulfuric acid as an etchant, and their hydrogen generation catalysts performances were evaluated. Sputtering time and power of Cu atoms have been varied in order to tailor the hydrogen generation performances. Similarly, dealloying time and the sulfuric acid concentration have also been altered to tune the morphologies of the resulted films. A maximum hydrogen generation rate of 35 mL min−1 was achieved when Cu sputtering power and time were 200 W and 60 min and while acid concentration and dealloying time were 18 M and 90 min, respectively. It has also been demonstrated that the Ru content in the alloy after dealloying gradually increased with the increasing the sputtering power of Cu. After 90 min dealloying, the Ru to Cu ratio increased to about 190 times that of bare alloy. This is the key issue for observing higher catalytic activity. Interestingly, we have also presented template-free nanoforest-like structure formation within the context of one-step alloying and dealloying used in this study. Last but not least, the long-time hydrogen generation performances of the catalysts system have also been evaluated along 3600 min. During the first 600 min, the catalytic activity was quite stable, while about 24% of the catalytic activity decayed after 3000 min, which still makes these systems available for the development of robust catalyst systems in the area of hydrogen generation.

  9. Stable catalyst layers for hydrogen permeable composite membranes

    Science.gov (United States)

    Way, J. Douglas; Wolden, Colin A

    2014-01-07

    The present invention provides a hydrogen separation membrane based on nanoporous, composite metal carbide or metal sulfide coated membranes capable of high flux and permselectivity for hydrogen without platinum group metals. The present invention is capable of being operated over a broad temperature range, including at elevated temperatures, while maintaining hydrogen selectivity.

  10. Evaluation of nickel and copper catalysts in biogas reforming for hydrogen production in SOFC

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Leonardo Alves; Martins, Andre Rosa; Rangel, Maria do Carmo, E-mail: mcarmov@ufba.br [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Grupo de Estudos em Cinetica e Catalise; Ballarini, Adriana; Maina, Silvia [Instituto de Investigaciones en Catalisis Y Petroquimica Ing. Jose Miguel Parera (INCAPE), Santa Fe (Argentina)

    2017-01-15

    The solid oxide fuel cells (SOFC) enable the efficient generation of clean energy, fitting the current requirements of the growing demand for electricity and for the environment preservation. When powered with biogas (from digesters of municipal wastes), the SOFCs also contribute to reduce the environmental impact of these wastes. The most suitable route to produce hydrogen inside SOFC from biogas is through dry reforming but the catalyst is easily deactivated by coke, because of the high amounts of carbon in the stream. A promising way to overcome this drawback is by adding a second metal to nickel-based catalysts. Aiming to obtain active, selective and stable catalysts for biogas dry reforming, solids based on nickel (15%) and copper (5%) supported on aluminum and magnesium oxide were studied in this work. Samples were prepared by impregnating the support with nickel and copper nitrate, followed by calcination at 500, 600 and 800 deg C. It was noted that all solids were made of nickel oxide, nickel aluminate and magnesium aluminate but no copper compound was found. The specific surface areas did not changed with calcination temperature but the nickel oxide average particles size increased. The solids reducibility decreased with increasing temperature. All catalysts were active in methane dry reforming, leading to similar conversions but different selectivities to hydrogen and different activities in water gas shift reaction (WGSR). This behavior was assigned to different interactions between nickel and copper, at different calcination temperatures. All catalysts were active in WGSR, decreasing the hydrogen to carbon monoxide molar ratio and producing water. The catalyst calcined at 500 deg C was the most promising one, leading to the highest hydrogen yield, besides the advantage of being produced at the lowest calcination temperature, requiring less energy in its preparation. (author)

  11. Stereoselective thymol hydrogenation. I. Kinetics of thymol hydrogenation on charcoal-supported platinum catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Besson, M.; Bullivant, L.; Nicolaus, N.; Gallezot, P. (Institut de Recherches sur la Catalyse-CNRS, Villeurbanne (France))

    1993-03-01

    The kinetics of thymol hydrogenation on a well-characterized supported platinum catalyst have been investigated in cyclohexane at temperatures between 313 and 373 K and under 3 MPa of hydrogen pressure. The relative rate constants of the different reaction pathways (hydrogenation via menthone or isomenthone, and direct hydrogenation to the four menthol diastereoisomers) were determined from the changes in composition of the reaction medium during the reaction process. It has been shown that hydrogenation via the menthone intermediates is the major route, the formation of the cis isomer (isomenthone) being favored. The configuration of the menthols, produced from direct hydrogenation or from the ketone intermediates, is controlled by the geometry of adsorption of the precursors on the metal surface, so that neoisomenthol with all substituents in the cis position is by far the most abundant steroisomer produced. 21 refs., 11 figs., 2 tabs.

  12. Magnetic Carbon Supported Palladium Nanoparticles: An Efficient and Sustainable Catalyst for Hydrogenation Reactions

    Science.gov (United States)

    Magnetic carbon supported Pd catalyst has been synthesized via in situ generation of nanoferrites and incorporation of carbon from renewable cellulose via calcination; the catalyst can be used for the hydrogenation of alkenes and reduction of aryl nitro compounds.

  13. Hydrogenation of toluene on Ni-Co-Mo supported zeolite catalysts ...

    African Journals Online (AJOL)

    -a, HY-b and Mordenite were prepared and characterized using many techniques for use as hydrotreating catalysts. In a preliminary investigation, toluene was employed as model compound to test the catalysts in hydrogenation, as a major ...

  14. Hydrogenation of coal in the presence of stationary wide-pore aluminium-cobalt-molybdenum catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Dembovskaya, E.A.; Karmanova, E.L.; Yulin, M.K.; Zaidman, N.M.; Milova, L.P.

    1984-01-01

    The possibility of hydrogenating brown coal using an AlCoMo catalyst has been demonstrated. The conversion can reach 82-84% and depends on the porous structure and concentration of the active components of the catalyst.

  15. Highly active iridium catalyst for hydrogen production from formic acid

    Institute of Scientific and Technical Information of China (English)

    Ying Du; Yang-Bin Shen; Yu-Lu Zhan; Fan-Di Ning; Liu-Ming Yan; Xiao-Chun Zhou

    2017-01-01

    Formic acid (FA) dehydrogenation has attracted a lot of attentions since it is a convenient method for H2 production.In this work,we designed a self-supporting fuel cell system,in which H2 from FA is supplied into the fuel cell,and the exhaust heat from the fuel cell supported the FA dehydrogenation.In order to realize the system,we synthesized a highly active and selective homogeneous catalyst IrCp*Cl2bpym for FA dehydrogenation.The turnover frequency (TOF) of the catalyst for FA dehydrogenation is as high as 7150 h-1 at 50 ℃,and is up to 144,000 h-1 at 90 ℃.The catalyst also shows excellent catalytic stability for FA dehydrogenation after several cycles of test.The conversion ratio of FA can achieve 93.2%,and no carbon monoxide is detected in the evolved gas.Therefore,the evolved gas could be applied in the proton exchange membrane fuel cell (PEMFC) directly.This is a potential technology for hydrogen storage and generation.The power density of the PEMFC driven by the evolved gas could approximate to that using pure hydrogen.

  16. Production of Catalyst-Free Hyperpolarised Ethanol Aqueous Solution via Heterogeneous Hydrogenation with Parahydrogen

    National Research Council Canada - National Science Library

    Salnikov, Oleg G; Kovtunov, Kirill V; Koptyug, Igor V

    2015-01-01

    An experimental approach for the production of catalyst-free hyperpolarised ethanol solution in water via heterogeneous hydrogenation of vinyl acetate with parahydrogen and the subsequent hydrolysis...

  17. Ni/Mo2C nanowires and their carbon-coated composites as efficient catalysts for nitroarenes hydrogenation

    Science.gov (United States)

    Shu, Yijin; He, Sina; Xie, Lifang; Chan, Hang Cheong; Yu, Xiang; Yang, Lichun; Gao, Qingsheng

    2017-02-01

    The hydrogenation of nitroarenes to value-added aromatic amines requires active and selective catalysts. Due to the good efficiency, economic cost and high earth-abundance, Ni-based nanostructures emerge as the promising catalysts, which are however limited by the poor dispersion and unsatisfied durability. Herein, Mo2C nanowires was introduced as a versatile support towards the highly dispersive Ni owing to the strong metal-support interactions on carbide surface, accomplishing the high activity in the hydrogenation of 3-nitrobenzoic acid, 4-nitrobenzoic acid and nitrobenzene. However, the presence of water that promoted the selective hydrogenation unfortunately deactivated Ni species. An effective carbon coating was further introduced to remarkably enhance the stability, protecting active Ni from corrosive H+ and H2O. This work elucidates a feasible way towards efficient and stable catalysts by the introduction of both carbide supports and carbon coating, shedding some light on the development of high-performance catalysts.

  18. Hydrogen production from biomass gasification using biochar as a catalyst/support.

    Science.gov (United States)

    Yao, Dingding; Hu, Qiang; Wang, Daqian; Yang, Haiping; Wu, Chunfei; Wang, Xianhua; Chen, Hanping

    2016-09-01

    Biochar is a promising catalyst/support for biomass gasification. Hydrogen production from biomass steam gasification with biochar or Ni-based biochar has been investigated using a two stage fixed bed reactor. Commercial activated carbon was also studied as a comparison. Catalyst was prepared with an impregnation method and characterized by X-ray diffraction, specific surface and porosity analysis, X-ray fluorescence and scanning electron micrograph. The effects of gasification temperature, steam to biomass ratio, Ni loading and bio-char properties on catalyst activity in terms of hydrogen production were explored. The Ni/AC catalyst showed the best performance at gasification temperature of 800°C, S/B=4, Ni loading of 15wt.%. Texture and composition characterization of the catalysts suggested the interaction between volatiles and biochar promoted the reforming of pyrolysis volatiles. Cotton-char supported Ni exhibited the highest activity of H2 production (64.02vol.%, 92.08mgg(-1) biomass) from biomass gasification, while rice-char showed the lowest H2 production. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Hydrogenation of xylose to xylitol on sponge nickel catalyst: a study of the process and catalyst deactivation kinetics

    Directory of Open Access Journals (Sweden)

    Mikkola J.-P.

    2003-01-01

    Full Text Available The kinetics of hydrogenation of xylose to xylitol on a sponge nickel catalyst (commonly referred to as Raney Ni catalyst and of catalyst deactivation were studied. Plausible explanations for the decrease in catalytic activity by means of surface studies, nitrogen adsorption and thermogravimetric analyses of the fresh and spent catalysts are presented. The kinetic parameters of the process were estimated by the use of a semi-competitive model, which allows full competition between the organic species and the hydrogen atoms for the adsorption sites on the catalyst surface (competitive case. In the model, a competitiveness factor (alpha is introduced to take into account that even after complete coverage of the surface by the organic species, interstitial sites remain for the adsorption of the hydrogen atoms.

  20. Methanol as a High Purity Hydrogen Source for Fuel Cells: A Brief Review of Catalysts and Rate Expressions

    Directory of Open Access Journals (Sweden)

    Madej-Lachowska Maria

    2017-03-01

    Full Text Available Hydrogen is the fuel of the future, therefore many hydrogen production methods are developed. At present, fuel cells are of great interest due to their energy efficiency and environmental benefits. A brief review of effective formation methods of hydrogen was conducted. It seems that hydrogen from steam reforming of methanol process is the best fuel source to be applied in fuel cells. In this process Cu-based complex catalysts proved to be the best. In presented work kinetic equations from available literature and catalysts are reported. However, hydrogen produced even in the presence of the most selective catalysts in this process is not pure enough for fuel cells and should be purified from CO. Currently, catalysts for hydrogen production are not sufficiently active in oxidation of carbon monoxide. A simple and effective method to lower CO level and obtain clean H2 is the preferential oxidation of monoxide carbon (CO-PROX. Over new CO-PROX catalysts the level of carbon monoxide can be lowered to a sufficient level of 10 ppm.

  1. Developing Enzyme and Biomimetic Catalysts for Upgrading Heavy Crudes via Biological Hydrogenation and Hydrodesulfurization

    Energy Technology Data Exchange (ETDEWEB)

    Borole, A P

    2006-08-22

    The recovery and conversion of heavy oils is limited due to the high viscosity of these crudes and their high heteroatom content. Conventional technology relies on thermochemical hydrogenation and hydrodesulfurization to address these problems and is energy intensive due to the high operating temperature and pressure. This project was initiated to explore biological catalysts for adding hydrogen to the heavy oil molecules. Biological enzymes are efficient at hydrogen splitting at very mild conditions such as room temperature and pressure, however, they are very specific in terms of the substrates they hydrogenate. The goal of the project was to investigate how the specificity of these enzymes can be altered to develop catalysts for oil upgrading. Three approaches were used. First was to perform chemical modification of the enzyme surface to improve binding of other non-natural substrates. Second approach was to expose the deeply buried catalytic active site of the enzyme by removal of protein scaffolding to enable better interaction with other substrates. The third approach was based on molecular biology to develop genetically engineered systems for enabling targeted structural changes in the enzyme. The first approach was found to be limited in success due to the non-specificity of the chemical modification and inability to target the region near the active site or the site of substrate binding. The second approach produced a smaller catalyst capable of catalyzing hydrogen splitting, however, further experimentation is needed to address reproducibility and stability issues. The third approach which targeted cloning of hydrogenase in alternate hosts demonstrated progress, although further work is necessary to complete the cloning process. The complex nature of the hydrogenase enzyme structure-function relationship and role of various ligands in the protein require significant more research to better understand the enzyme and to enable success in strategies in

  2. Enhancing the stability of copper chromite catalysts for the selective hydrogenation of furfural using ALD overcoating

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hongbo; Lei, Yu; Kropf, A. Jeremy; Zhang, Guanghui; Elam, Jeffrey W.; Miller, Jeffrey T.; Sollberger, Fred; Ribeiro, Fabio; Akatay, M. Cem; Stach, Eric A.; Dumesic, James A.; Marshall, Christopher L.

    2014-08-01

    The stability of a gas-phase furfural hydrogenation catalyst (CuCr2O4 center dot CuO) was enhanced by depositing a thin Al2O3 layer using atomic layer deposition (ALD). Based on temperature-programed reduction (TPR) measurements, the reduction temperature of Cu was raised significantly, and the activation energy for furfural reduction was decreased following the ALD treatment. Thinner ALD layers yielded higher furfural hydrogenation activities. X-ray absorption fine structure (XAFS) spectroscopy studies indicated that Cu1+/Cu-0 are the active species for furfural reduction.

  3. Two-phase model of hydrogen transport to optimize nanoparticle catalyst loading for hydrogen evolution reaction

    DEFF Research Database (Denmark)

    Kemppainen, Erno; Halme, Janne; Hansen, Ole

    2016-01-01

    With electrocatalysts it is important to be able to distinguish between the effects of mass transport and reaction kinetics on the performance of the catalyst. When the hydrogen evolution reaction (HER) is considered, an additional and often neglected detail of mass transport in liquid is the evo......With electrocatalysts it is important to be able to distinguish between the effects of mass transport and reaction kinetics on the performance of the catalyst. When the hydrogen evolution reaction (HER) is considered, an additional and often neglected detail of mass transport in liquid...... current densities the increase in the gas volume fraction makes the H2 surface concentration nonlinear with respect to the current density. Compared to the typical diffusion layer model, our model is an extension that allows more detailed studies of reaction kinetics and mass transport in the electrolyte...

  4. Optimization of catalyst layer composition for PEMFC using graphene-based oxygen reduction reaction catalysts

    Science.gov (United States)

    Park, Jong Cheol; Park, Sung Hyeon; Chung, Min Wook; Choi, Chang Hyuck; Kho, Back Kyun; Woo, Seong Ihl

    2015-07-01

    The focus in recent years is on developing high performance non-precious metal catalysts (NPMCs) to reduce the catalyst cost in fuel cells. However, little attention has been paid to improve the utilization of NPMCs. Thus, this study focuses on the optimization of electrode component, particularly the Nafion content. With the synthesized graphene based oxygen reduction reaction (ORR) catalyst, the catalyst inks were prepared at various Nafion contents with suitable amounts of catalysts sprayed on the gas diffusion media. Twenty different single cells were assembled and measured for polarization, resistance and electrochemical impedance. Electrodes of 66.7 and 50.0% Nafion contents showed the highest performance for hydrogen/oxygen and hydrogen/air operation, respectively. These results were explained using the electrochemical impedance spectra, where the highest performance electrode resulted with the lowest charge transfer resistance. Moreover, negligible change in performance was observed during the 80 h of stability test. The optimization compositions of NPMC-based MEAs were very different to Pt-based MEAs, indicating the importance of optimization studies for the practical use of NPMCs.

  5. Characterization of the various catalyst for solvent hydrogenation at 1t/d PSU; 1t/d PSU ni okeru kakushu yozai suisoka shokubai no seino hyoka

    Energy Technology Data Exchange (ETDEWEB)

    Kakebayashi, H.; Nogami, Y.; Inokuchi, K. [Mitsui SRC Development Co. Ltd., Tokyo (Japan); Aihara, Y.; Imada, K. [Nippon Steel Corp., Tokyo (Japan)

    1996-10-28

    Performance of various catalysts for hydrogenation of recycle solvent was evaluated for the operation of NEDOL process 1 t/d process supporting unit (PSU). Distillate between 220 and 538{degree}C derived from the liquefaction of Tanito Harum coal was used as recycle solvent. Deactivation behaviors of catalysts were compared using a prediction equation of catalyst life, by which aromatic carbon index (fa) after hydrogenation can be determined from the fa of recycle oil before hydrogenation, reaction temperature, and total hydrogenation time. Total hydrogenation time satisfying the {Delta}fa, 0.05 before and after hydrogenation were 8,000, 4,000, and 2,000 hours for NiMo-based catalysts C, A, and B, respectively. Catalyst C showed the longest life. Used catalysts were also characterized. The catalyst C showed larger mean pore size than those of the others, which resulted in the longer life due to the delay of pore blockage. From measurements by XPS and EPMA, relative atomic concentration of carbon increased remarkably after the use for all of catalysts, which was considered to be due to the adhesion of hydrocarbons. Increase of metal atoms, such as Fe and Cr, was also observed due to the contamination of entrainment residues. Deactivation of catalysts was caused by the adhesion of hydrocarbons, and metallic compounds, such as Fe and Cr. 3 refs., 1 fig., 5 tabs.

  6. Characterization of Fe-Co-Mn catalysts after carbon monoxide hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez C, S.L.; Serbia, M.A.; Baechler, R.; Orozco, J. [Laboratorio de Cinetica y Catalisis, Departamento de Quimica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101A (Venezuela); e-mail: goncor@ula.ve

    2003-07-01

    An Fe-Co-Mn catalysts series after hydrogenation of carbon monoxide has been characterized. The XRD analysis shows the magnetite as main crystalline phase after reaction, in addition of carbon and carbide phases. All these phases lead to hydrogen consumption and oxidation rate changes on Fe-Co-Mn catalysts. A phase transformation superficial diagram is analysed. (Author)

  7. A highly active cyclometallated iridium catalyst for the hydrogenation of imines.

    Science.gov (United States)

    Villa-Marcos, Barbara; Tang, Weijun; Wu, Xiaofeng; Xiao, Jianliang

    2013-09-25

    A cyclometallated iridium complex containing an imino ligand has been shown to catalyse the hydrogenation of imines. The catalyst is highly active and selective for imino bonds, with a wide variety of imines being hydrogenated in less than 1 hour at a substrate/catalyst (S/C) ratio of 2000 at 20 bar H2 pressure and 75 °C.

  8. Short Review: Cu Catalyst for Autothermal Reforming Methanol for Hydrogen Production

    Directory of Open Access Journals (Sweden)

    Ho-Shing Wu

    2012-06-01

    Full Text Available Hydrogen is a promising alternative energy sources, hydrogen can be used in fuel cell applications to pro-ducing electrical energy and water as byproduct. Therefore, fuel cell is a simple application and environ-mentally friendly oriented technology. Recent years various methods have been conducted to produce hy-drogen. Those methods are derived from various sources such as methanol, ethanol, gasoline, hydrocarbons. This article presents a brief review a parameter process of that affects in autothermal reforming methanol use Cu-based catalysts for production of hydrogen. Copyright © 2012 BCREC UNDIP. All rights reserved.Received: 3rd January 2012; Revised: 23rd February 2012; Accepted: 28th February 2012[How to Cite: H.S. Wu, and D. Lesmana. (2012. Short Review: Cu Catalyst for Autothermal Reforming Methanol for Hydrogen Production. Bulletin of Chemical Reaction Engineering & Catalysis, 7 (1: 27-42. doi:10.9767/bcrec.7.1.1284.27-42][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.7.1.1284.27-42 ] | View in 

  9. Methane Steam Reforming Kinetics for a Rhodium-Based Catalyst

    DEFF Research Database (Denmark)

    Jakobsen, Jon Geest; Jakobsen, M.; Chorkendorff, Ib

    2010-01-01

    Methane steam reforming is the key reaction to produce synthesis gas and hydrogen at the industrial scale. Here the kinetics of methane steam reforming over a rhodium-based catalyst is investigated in the temperature range 500-800 A degrees C and as a function of CH4, H2O and H-2 partial pressures...

  10. Molecular metal-Oxo catalysts for generating hydrogen from water

    Science.gov (United States)

    Long, Jeffrey R; Chang, Christopher J; Karunadasa, Hemamala I

    2015-02-24

    A composition of matter suitable for the generation of hydrogen from water is described, the positively charged cation of the composition having the general formula [(PY5W.sub.2)MO].sup.2+, wherein PY5W.sub.2 is (NC.sub.5XYZ)(NC.sub.5H.sub.4).sub.4C.sub.2W.sub.2, M is a transition metal, and W, X, Y, and Z can be H, R, a halide, CF.sub.3, or SiR.sub.3, where R can be an alkyl or aryl group. The two accompanying counter anions, in one embodiment, can be selected from the following Cl.sup.-, I.sup.-, PF.sub.6.sup.-, and CF.sub.3SO.sub.3.sup.-. In embodiments of the invention, water, such as tap water containing electrolyte or straight sea water can be subject to an electric potential of between 1.0 V and 1.4 V relative to the standard hydrogen electrode, which at pH 7 corresponds to an overpotential of 0.6 to 1.0 V, with the result being, among other things, the generation of hydrogen with an optimal turnover frequency of ca. 1.5 million mol H.sub.2/mol catalyst per h.

  11. Hydrogen production via steam reforming of ethyl alcohol over nano-structured indium oxide catalysts

    Science.gov (United States)

    Umegaki, Tetsuo; Kuratani, Kentaro; Yamada, Yusuke; Ueda, Atsushi; Kuriyama, Nobuhiro; Kobayashi, Tetsuhiko; Xu, Qiang

    2008-05-01

    Mesoporous and worm-like In2O3 catalysts have been prepared using KIT-6 and MCM-41 silicas as templates, which show low crystallinities and high surface areas. Compared with commercial In2O3 catalyst with low surface area, these two nano-structured In2O3 catalysts exhibit higher catalytic activity for steam reforming of ethyl alcohol at low temperature to produce hydrogen containing no detectable CO impurity, presenting an advantage in comparison with the previous reported catalysts.

  12. Molybdenum sulfide catalyst for use in destructive hydrogenation of coal

    Energy Technology Data Exchange (ETDEWEB)

    Krichko, A.A.; Shpirt, M.Ya.; Glazunov, M.P.; Zekel' , L.A.; Krasnobaeva, N.V.; Plavnik, G.M.; Khrustaleva, G.N.; Aliev, A.D.

    1988-09-01

    Studies composition, structure and physical-chemical properties of catalytically active particles obtained from the breakdown of emulsion formed from water solution of ammonium paramolybdate (concentration 200 g/liter) and pasteformer. Uses petroleum distillation residue (b.p. above 260 C) having elemental composition C 85.8%, H 11.9%, S 1.69% and N 0.3% as dispersion medium. Establishes that hexagonal, near spherical particles of molybdenite (0.02-1 micrometer radius) are formed in destructive hydrogenation conditions, high catalytic activity of particles is governed by small spherical crystalline grains providing easy contact with high molecular fragments of coal substance and enables the particles, together with pasteformers, to penetrate coal micropore system. Electron-microscopic pictures, diffractograms and other data related to the catalyst are given. 10 refs.

  13. Bioinspired Molecular Co-Catalysts Bonded to a Silicon Photocathode for Solar Hydrogen Evolution

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Yidong

    2011-11-08

    The production of fuels from sunlight represents one of the main challenges in the development of a sustainable energy system. Hydrogen is the simplest fuel to produce and although platinum and other noble metals are efficient catalysts for photoelectrochemical hydrogen evolution earth-abundant alternatives are needed for large-scale use. We show that bioinspired molecular clusters based on molybdenum and sulphur evolve hydrogen at rates comparable to that of platinum. The incomplete cubane-like clusters (Mo{sub 3}S{sub 4}) efficiently catalyse the evolution of hydrogen when coupled to a p-type Si semiconductor that harvests red photons in the solar spectrum. The current densities at the reversible potential match the requirement of a photoelectrochemical hydrogen production system with a solar-to-hydrogen efficiency in excess of 10% (ref. 16). The experimental observations are supported by density functional theory calculations of the Mo{sub 3}S{sub 4} clusters adsorbed on the hydrogen-terminated Si(100) surface, providing insights into the nature of the active site.

  14. Molybdenum phosphosulfide: an active, acid-stable, earth-abundant catalyst for the hydrogen evolution reaction.

    Science.gov (United States)

    Kibsgaard, Jakob; Jaramillo, Thomas F

    2014-12-22

    Introducing sulfur into the surface of molybdenum phosphide (MoP) produces a molybdenum phosphosulfide (MoP|S) catalyst with superb activity and stability for the hydrogen evolution reaction (HER) in acidic environments. The MoP|S catalyst reported herein exhibits one of the highest HER activities of any non-noble-metal electrocatalyst investigated in strong acid, while remaining perfectly stable in accelerated durability testing. Whereas mixed-metal alloy catalysts are well-known, MoP|S represents a more uncommon mixed-anion catalyst where synergistic effects between sulfur and phosphorus produce a high-surface-area electrode that is more active than those based on either the pure sulfide or the pure phosphide. The extraordinarily high activity and stability of this catalyst open up avenues to replace platinum in technologies relevant to renewable energies, such as proton exchange membrane (PEM) electrolyzers and solar photoelectrochemical (PEC) water-splitting cells. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Low metal loading catalysts used for the selective hydrogenation of styrene

    Energy Technology Data Exchange (ETDEWEB)

    Badano, Juan; Lederhos, Cecilia; Quiroga, Monica; L' Argentiere, Pablo [Consejo Nacional de Investigaciones Cientificas y Tecnicas, Santa Fe (Argentina). Universidad Nacional del Litoral. Inst. de Investigaciones en Catalisis y Petroquimica; Coloma-Pascual, Fernando [Universidad de Alicante (Spain). Facultad de Ciencias. Servicios Tecnicos de Investigacion

    2010-07-01

    A series of Group VIII metal catalysts was obtained for the semi-hydrogenation of styrene. Catalysts were characterized by Hydrogen Chemisorption, TPR and XPS. Palladium, rhodium and platinum low metal loading prepared catalysts presented high activity and selectivity (ca. 98%) during the semi-hydrogenation of styrene, being palladium the most active catalyst. The ruthenium catalyst also presented high selectivity (ca. 98%), but the lowest activity. For the palladium catalyst, the influence of the precursor salt and of the reduction temperature on the activity and selectivity were studied. The following activity series was obtained: PdN-423 > PdCl-673 > PdCl-373> PtCl-673 > RhCl-673 >> RuCl-673. As determined by XPS, differences in activity could be attributed, at least in part, to electronic effects (author)

  16. Hydrogenation of coal in the presence of stationary wide-pore alumo-cobalt-molybdenum catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Dembovskaya, E.A.; Karmanova, E.L.; Yulin, M.K.; Zaidman, N.M.; Milova, L.P.

    1984-05-01

    Results are presented from investigations of hydrogenation of Irsha-Borodinsk brown coal on stationary wide-pore alumo-cobalt-molybdenum catalysts. A significant part of the surface area of the catalysts used was made up of pores with radii exceeding 1000 Angstrom. Without the catalysts only 58% of the coal organic mass was converted; with the catalysts 67-84%. The method of hydrogenation was developed by the Institute of Fossil Fuels. The experimental catalysts were prepared by the Institute of Catalysis. Hydrogenation was carried out in a drum autoclave at 420-430 C. The activity of the catalysts was attributed to their porous structure, i.e. a specific ratio between small, medium and large pores, and to the concentration of active components, especially molybdenum oxide. 8 references.

  17. Hydrophilic cobalt sulfide nanosheets as a bifunctional catalyst for oxygen and hydrogen evolution in electrolysis of alkaline aqueous solution.

    Science.gov (United States)

    Zhu, Mingchao; Zhang, Zhongyi; Zhang, Hu; Zhang, Hui; Zhang, Xiaodong; Zhang, Lixue; Wang, Shicai

    2018-01-01

    Hydrophilic medium and precursors were used to synthesize a hydrophilic electro-catalyst for overall water splitting. The cobalt sulfide (Co 3 S 4 ) catalyst exhibits a layered nanosheet structure with a hydrophilic surface, which can facilitate the diffusion of aqueous substrates into the electrode pores and towards the active sites. The Co 3 S 4 catalyst shows excellent bifunctional catalytic activity for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline solution. The assembled water electrolyzer based on Co 3 S 4 exhibits better performance and stability than that of Pt/C-RuO 2 catalyst. Thereforce the hydrophilic Co 3 S 4 is a highly promising bifunctional catalyst for the overall water splitting reaction. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Determination of the dominant catalyst derived from the classic [RhCp*Cl₂]₂ precatalyst system: Is it single-metal Rh₁Cp*-based, subnanometer Rh₄ cluster-based, or Rh(0)n nanoparticle-based cyclohexene hydrogenation catalysis at room temperature and mild pressures?

    Energy Technology Data Exchange (ETDEWEB)

    Bayram, Ercan [Colorado State Univ., Fort Collins, CO (United States); Linehan, John C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Fulton, John L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Szymczak, Nathaniel K. [Univ. of Michigan, Ann Arbor, MI (United States); Finke, Richard G. [Colorado State Univ., Fort Collins, CO (United States)

    2015-05-27

    Determining the kinetically dominant catalyst in a given catalytic system is a forefront topic in catalysis. The [RhCp*Cl₂]₂ (Cp* =[η⁵-C₅(CH₃)₅]) system pioneered by Maitlis and co-workers is a classic precatalyst system from which homogeneous mononuclear Rh₁, subnanometer Rh₄ cluster, and heterogeneous polymetallic Rh(0)n nanoparticle have all arisen as viable candidates for the true hydrogenation catalyst, depending on the precise substrate, H₂ pressure, temperature, and catalyst concentration conditions. Addressed herein is the question of whether the prior assignment of homogeneous, mononuclear Rh₁Cp*-based catalysis is correct, or are trace Rh₄ subnanometer clusters or possibly Rh(0)n nanoparticles the dominant, actual cyclohexene hydrogenation catalyst at 22 °C and 2.7 atm initial H₂ pressure? The observation herein of Rh₄ species by in operando-X-ray absorption fine structure (XAFS) spectroscopy, at the only slightly more vigorous conditions of 26 °C and 8.3 atm H₂ pressure, and the confirmation of Rh₄ clusters by ex situ mass spectroscopy raises the question of the dominant, room temperature, and mild pressure cyclohexene hydrogenation catalyst derived from the classic [RhCp*Cl₂]₂ precatalyst pioneered by Maitlis and co-workers. Ten lines of evidence are provided herein to address the nature of the true room temperature and mild pressure cyclohexene hydrogenation catalyst derived from [RhCp*Cl₂]₂. Especially significant among those experiments are quantitative catalyst poisoning experiments, in the present case using 1,10-phenanthroline. Those poisoning studies allow one to distinguish mononuclear Rh₁, subnanometer Rh₄ cluster, and Rh(0)n nanoparticle catalysis hypotheses. The evidence obtained provides a compelling case for a mononuclear, Rh₁Cp*-based cyclohexene hydrogenation catalyst at 22 °C and 2.7 atm H₂ pressure. The resultant methodology, especially the quantitative

  19. A RhxSy/C Catalyst for the Hydrogen Oxidation and Hydrogen Evolution Reactions in HBr

    Energy Technology Data Exchange (ETDEWEB)

    Masud, J; Nguyen, TV; Singh, N; McFarland, E; Ikenberry, M; Hohn, K; Pan, CJ; Hwang, BJ

    2015-01-13

    Rhodium sulfide (Rh2S3) on carbon support was synthesized by refluxing rhodium chloride with ammonium thiosulfate. Thermal treatment of Rh2S3 at high temperatures (600 degrees C to 850 degrees C) in presence of argon resulted in the transformation of Rh2S3 into Rh3S4, Rh17S15 and Rh which were characterized by TGA/DTA, XRD, EDX, and deconvolved XPS analyses. The catalyst particle size distribution ranged from 3 to 12 nm. Cyclic voltammetry and rotating disk electrode measurements were used to evaluate the catalytic activity for hydrogen oxidation and evolution reactions in H2SO4 and HBr solutions. The thermally treated catalysts show high activity for the hydrogen reactions. The exchange current densities (i(o)) of the synthesized RhxSy catalysts in H-2-saturated 1M H2SO4 and 1M HBr for HER and HOR were 0.9 mA/cm(2) to 1.0 mA/cm(2) and 0.8 to 0.9 mA/cm(2), respectively. The lower i(o) values obtained in 1M HBr solution compared to in H2SO4 might be due to the adsorption of Br- on the active surface. Stable electrochemical active surface area (ECSA) of RhxSy catalyst was obtained for CV scan limits between 0 V and 0.65 V vs. RHE. Scans with upper voltage limit beyond 0.65 V led to decreased and unreproducible ECSA measurements. (C) The Author(s) 2015. Published by ECS. All rights reserved.

  20. Environmental Engineering of Pd Nanoparticle Catalysts for Catalytic Hydrogenation of CO2 and Bicarbonate.

    Science.gov (United States)

    Lee, Li-Chen; Xing, Xiaoyu; Zhao, Yan

    2017-10-24

    The extraordinary catalytic properties of enzymes are derived not only from their catalytic groups but also the unique properties of the active site. Tuning the microenvironment of synthetic catalysts is expected to enhance their performance if effective strategies can be developed. Interfacially cross-linked reverse micelles were prepared from three different cross-linkable surfactants. Pd nanoparticles were deposited in the core of the micelle for the catalytic hydrogenation of bicarbonate and CO2. The catalytic performance was found to depend heavily on the nature of the headgroup of the surfactant. Quaternary ammonium-based surfactants through ion exchange could bring bicarbonate to the catalytic center, whereas tertiary amine-based surfactants worked particularly well in CO2 hydrogenation, with turnover numbers an order of magnitude higher than that of commercially available Pd/C. The amines were proposed to bring CO2 to the proximity of the catalysts through reversible formation of carbamate, in the nanospace of the hydrophilic core of the cross-linked reverse micelle. In the bicarbonate reduction, additional improvement of the catalysts was achieved through localized sol-gel synthesis that introduced metal oxide near the catalytic metal.

  1. Room temperature hydrogen generation from hydrolysis of ammonia-borane over an efficient NiAgPd/C catalyst

    KAUST Repository

    Hu, Lei

    2014-12-01

    NiAgPd nanoparticles are successfully synthesized by in-situ reduction of Ni, Ag and Pd salts on the surface of carbon. Their catalytic activity was examined in ammonia borane (NH3BH3) hydrolysis to generate hydrogen gas. This nanomaterial exhibits a higher catalytic activity than those of monometallic and bimetallic counterparts and a stoichiometric amount of hydrogen was produced at a high generation rate. Hydrogen production rates were investigated in different concentrations of NH3BH3 solutions, including in the borates saturated solution, showing little influence of the concentrations on the reaction rates. The hydrogen production rate can reach 3.6-3.8 mol H2 molcat -1 min-1 at room temperature (21 °C). The activation energy and TOF value are 38.36 kJ/mol and 93.8 mol H2 molcat -1 min-1, respectively, comparable to those of Pt based catalysts. This nanomaterial catalyst also exhibits excellent chemical stability, and no significant morphology change was observed from TEM after the reaction. Using this catalyst for continuously hydrogen generation, the hydrogen production rate can be kept after generating 6.2 L hydrogen with over 10,000 turnovers and a TOF value of 90.3 mol H2 molcat -1 min-1.

  2. Low-temperature hydrogen production from water and methanol using Pt/α-MoC catalysts

    Science.gov (United States)

    Lin, Lili; Zhou, Wu; Gao, Rui; Yao, Siyu; Zhang, Xiao; Xu, Wenqian; Zheng, Shijian; Jiang, Zheng; Yu, Qiaolin; Li, Yong-Wang; Shi, Chuan; Wen, Xiao-Dong; Ma, Ding

    2017-03-01

    Polymer electrolyte membrane fuel cells (PEMFCs) running on hydrogen are attractive alternative power supplies for a range of applications, with in situ release of the required hydrogen from a stable liquid offering one way of ensuring its safe storage and transportation before use. The use of methanol is particularly interesting in this regard, because it is inexpensive and can reform itself with water to release hydrogen with a high gravimetric density of 18.8 per cent by weight. But traditional reforming of methanol steam operates at relatively high temperatures (200-350 degrees Celsius), so the focus for vehicle and portable PEMFC applications has been on aqueous-phase reforming of methanol (APRM). This method requires less energy, and the simpler and more compact device design allows direct integration into PEMFC stacks. There remains, however, the need for an efficient APRM catalyst. Here we report that platinum (Pt) atomically dispersed on α-molybdenum carbide (α-MoC) enables low-temperature (150-190 degrees Celsius), base-free hydrogen production through APRM, with an average turnover frequency reaching 18,046 moles of hydrogen per mole of platinum per hour. We attribute this exceptional hydrogen production—which far exceeds that of previously reported low-temperature APRM catalysts—to the outstanding ability of α-MoC to induce water dissociation, and to the fact that platinum and α-MoC act in synergy to activate methanol and then to reform it.

  3. Final Report: Cathode Catalysis in Hydrogen/Oxygen Fuel Cells: New Catalysts, Mechanism, and Characterization

    Energy Technology Data Exchange (ETDEWEB)

    Gewirth, Andrew A. [Univ. of Illinois, Urbana, IL (United States). Dept. of Chemistry; Kenis, Paul J. [Univ. of Illinois, Urbana, IL (United States). Dept. of Chemical and Biomolecular Engineering; Nuzzo, Ralph G. [Univ. of Illinois, Urbana, IL (United States). Dept. of Chemistry; Rauchfuss, Thomas B. [Univ. of Illinois, Urbana, IL (United States). Dept. of Chemistry

    2016-01-18

    In this research, we prosecuted a comprehensive plan of research directed at developing new catalysts and new understandings relevant to the operation of low temperature hydrogen-oxygen fuel cells. The focal point of this work was one centered on the Oxygen Reduction Reaction (ORR), the electrochemical process that most fundamentally limits the technological utility of these environmentally benign energy conversion devices. Over the period of grant support, we developed new ORR catalysts, based on Cu dimers and multimers. In this area, we developed substantial new insight into design rules required to establish better ORR materials, inspired by the three-Cu active site in laccase which has the highest ORR onset potential of any material known. We also developed new methods of characterization for the ORR on conventional (metal-based) catalysts. Finally, we developed a new platform to study the rate of proton transfer relevant to proton coupled electron transfer (PCET) reactions, of which the ORR is an exemplar. Other aspects of work involved theory and prototype catalyst testing.

  4. Support screening studies on the hydrogenation of levulinic acid to γ‐valerolactone in water using RU catalysts

    NARCIS (Netherlands)

    Piskun, Anna; Winkelman, Jozef G M; Tang, Zhenchen; Heeres, Hero Jan

    2016-01-01

    γ-Valerolactone (GVL) has been identified as a sustainable platform chemical for the production of carbon-based chemicals. Here we report a screening study on the hydrogenation of levulinic acid (LA) to GVL in water using a wide range of ruthenium supported catalysts in a batch set-up (1 wt. % Ru,

  5. Development of vapor phase hydrogenation and of catalysts immune to poison (abstract)

    Energy Technology Data Exchange (ETDEWEB)

    1942-10-16

    The development of catalysts immune to poison and the development of vapor-phase hydrogenation were closely connected and they were considered together. Catalysts used at high thruputs and high partial pressures showed rapid deterioration of their activity caused by deposition and condensation of high-molecular-weight substances on the surface of the catalysts. This phenomenon made it necessary to divide hydrogenation into two phases: the liquid phase and the vapor phase. The first of the vapor-phase operating catalysts was catalyst 3510, which consisted of zinc--magnesium molybdate. Development of catalyst 5058, which consisted of pure tungsten disulfide and was produced by decomposing ammonium--sulfotungstate in H/sub 2/ atmosphere, largely terminated development of vapor-phase catalysts. Maximum activity had been obtained. Compared to 3510, two to three times as much gasoline was produced per hour with a fixed volume of catalyst, besides being able to work at a temperature about 100/sup 0/C lower, and gasification losses were considerably smaller. In order to use 5058 in mass production, the dry catalyst powder had to be compressed into cylindrical shapes 10 mm in diameter. The demands for higher antiknock gasolines in the processing of certain paraffinic raw material could not be met by 5058 because of its strong hydrogenation effect, and the dilute catalyst 6434, consisting of 90% Fullers earth treated with HF and 10% WS/sub 2/, was developed for this. 3 tables.

  6. CO hydrogenation to methanol on Cu–Ni catalysts

    DEFF Research Database (Denmark)

    Studt, Felix; Abild-Pedersen, Frank; Wu, Qiongxiao

    2012-01-01

    two descriptors, the carbon oxygen binding energies, are constructed. A micro-kinetic model of CO hydrogenation is developed and a volcano-shaped relation based on the two descriptors is obtained for methanol synthesis. A large number of bimetallic alloys with respect to the two descriptors...

  7. Development of novel catalysts for the photocatalytic hydrogen formation

    Energy Technology Data Exchange (ETDEWEB)

    Pilz, Thomas David

    2011-11-16

    For future conversion of sunlight into chemical energy, intramolecular systems for artifical photosynthesis were developed in several stages. This comprised the fabrication of novel ligands and the resulting charge transfer chromophores (Ru(bpy)3-type) and/or catalytically active complexes (Pt, Pd). These were combined into heteronuclear diades consisting of covalently bonded functional subunits. In particular, the chromophores and catalysis centers were bridged so that their individual properties were retained while their individual functions were combined into a supramolecular photocatalyst. This makes it possible to reduce protons to hydrogen on these catalysts when exposed to light. As bridging units, oligodentate ligands were produced and used that can coordinate the active metal centers via bipyridines and N-heterocyclic carbenes (NHC). A number of such heterobimetal complexes, their initial compounds and appropriate reference compounds were produced, characterized, and compared. Apart from structural, photophysical and electrochemical analyses, also successful catalysis experiment were carried out with the manufactured photocatalysts for light-induced hydrogen production from water. Further representative control experiments and dynamic light scattering analyses were carried out in order to gain deeper understanding of the processes going on during catalysis. By comparing the properties of the fabricated catalysts with selected reference compounds, information was obtained on the structure-property relationships of the systems. (orig.) [German] Fuer die zukuenftige Umwandlung von Sonnenlicht in chemische Energie wurden schrittweise intramolekular arbeitende Systeme fuer eine artifizielle Photosynthese aufgebaut. Dabei wurde eine Anzahl von neuen Liganden und den resultierenden Charge-Transfer-Chromophoren (Ru(bpy)3-artig) bzw. katalyseaktiven Komplexen (Pt, Pd) hergestellt. Diese wurden zu heteronuklearen Diaden zusammengefuegt, welche aus kovalent

  8. Enlarged test catalysts during the hydrogenation of 1,4-butynediol to 1,4-butanediol

    Directory of Open Access Journals (Sweden)

    Zhaksyntay Kairbekov

    2013-09-01

    Full Text Available The highly effective catalyzer for butynediol-1;4 hydrogenation was designed and synthesized. Enlarged tests showed that the selectivity on butanediol-1.4 at the hydrogenation of butynediol-1.4 on the alloyed catalyst SKN-39H during 320 h was 84.6 %; that on 18 % higher than for  industrial MNH. The yield of product on the catalyst SKN-39 increases slowly from 3.1 to 7.3 % when on a catalyst MNH – 7.1 to 11.7 % from the initial content of butynediol-1;4. At the hydrogenation of  butynediol on catalyst SKN-39H process efficiency increases in 1.5-2 times and product purity on 2-3 % is higher in comparing with the industrial catalyst MNH. 

  9. Ceria-based model catalysts: fundamental studies on the importance of the metal-ceria interface in CO oxidation, the water-gas shift, CO2 hydrogenation, and methane and alcohol reforming.

    Science.gov (United States)

    Rodriguez, José A; Grinter, David C; Liu, Zongyuan; Palomino, Robert M; Senanayake, Sanjaya D

    2017-04-03

    Model metal/ceria and ceria/metal catalysts have been shown to be excellent systems for studying fundamental phenomena linked to the operation of technical catalysts. In the last fifteen years, many combinations of well-defined systems involving different kinds of metals and ceria have been prepared and characterized using the modern techniques of surface science. So far most of the catalytic studies have been centered on a few reactions: CO oxidation, the hydrogenation of CO2, and the production of hydrogen through the water-gas shift reaction and the reforming of methane or alcohols. Using model catalysts it has been possible to examine in detail correlations between the structural, electronic and catalytic properties of ceria-metal interfaces. In situ techniques (X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, infrared spectroscopy, scanning tunneling microscopy) have been combined to study the morphological changes under reaction conditions and investigate the evolution of active phases involved in the cleavage of C-O, C-H and C-C bonds. Several studies with model ceria catalysts have shown the importance of strong metal-support interactions. In general, a substantial body of knowledge has been acquired and concepts have been developed for a more rational approach to the design of novel technical catalysts containing ceria.

  10. Hydrogen spillover effects on Pt-Rh modified Co-clay catalysts for heavy oil upgrading

    Energy Technology Data Exchange (ETDEWEB)

    Al-Saleh, M.A.; Hossain, M.M.; Shalabi, M.A. [Center for Refining and Petrochemicals, Research Institute, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Kimura, T.; Inui, T. [Japan Petroleum Energy Center, Kanagawa (Japan)

    2003-10-28

    Hydrogen spillover effects on noble metal-promoted Co/HPS (high porous saponite) catalysts have been investigated by temperature-programmed reduction (TPR) studies and batch autoclave reactor trials. Pt and Rh noble metals were used to introduce hydrogen spillover on Co/HPS. TPR studies showed that Pt-Rh combination has more significant effects on the reducibility of Co species on HPS catalysts than the unpromoted and single noble metal (Pt, Rh individually)-promoted catalysts. The Pt-Rh combination shifts the TPR peaks to lower temperatures. Two Pt-Rh-promoted catalysts were evaluated in batch autoclave reactor (at 400C and 140kg/cm{sup 2}) using vacuum gas oil (VGO) as the feedstock. Pt-Rh-promoted catalysts showed higher activity for both hydrocracking and hydrodesulfurization of the heavy feed than the unpromoted Co/HPS catalyst.

  11. Catalyst Deactivation and Regeneration Processes in Biogas Tri-Reforming Process. The Effect of Hydrogen Sulfide Addition

    Directory of Open Access Journals (Sweden)

    Urko Izquierdo

    2018-01-01

    Full Text Available This work studies Ni-based catalyst deactivation and regeneration processes in the presence of H2S under a biogas tri-reforming process for hydrogen production, which is an energy vector of great interest. 25 ppm of hydrogen sulfide were continuously added to the system in order to provoke an observable catalyst deactivation, and once fully deactivated two different regeneration processes were studied: a self-regeneration and a regeneration by low temperature oxidation. For that purpose, several Ni-based catalysts and a bimetallic Rh-Ni catalyst supported on alumina modified with CeO2 and ZrO2 were used as well as a commercial Katalco 57-5 for comparison purposes. Ni/Ce-Al2O3 and Ni/Ce-Zr-Al2O3 catalysts almost recovered their initial activity. For these catalysts, after the regeneration under oxidative conditions at low temperature, the CO2 conversions achieved—79.5% and 86.9%, respectively—were significantly higher than the ones obtained before sulfur poisoning—66.7% and 45.2%, respectively. This effect could be attributed to the support modification with CeO2 and the higher selectivity achieved for the Reverse Water-Gas-Shift (rWGS reaction after catalysts deactivation. As expected, the bimetallic Rh-Ni/Ce-Al2O3 catalyst showed higher resistance to deactivation and its sulfur poisoning seems to be reversible. In the case of the commercial and Ni/Zr-Al2O3 catalysts, they did not recover their activity.

  12. Iron Phthalocyanine as New Efficient Catalyst for Catalytic Transfer Hydrogenation of Simple Aldehydes and Ketones

    Czech Academy of Sciences Publication Activity Database

    Bata, P.; Notheisz, F.; Klusoň, Petr; Zsigmond, A.

    2015-01-01

    Roč. 29, JAN 2015 (2015), s. 45-49 ISSN 0268-2605 Institutional support: RVO:67985858 Keywords : heterogenized complexes * catalytic transfer hydrogenation * reusable catalyst Subject RIV: CC - Organic Chemistry Impact factor: 2.452, year: 2015

  13. Transforming nonselective into chemoselective metal catalysts for the hydrogenation of substituted nitroaromatics.

    Science.gov (United States)

    Corma, Avelino; Serna, Pedro; Concepción, Patricia; Calvino, José Juan

    2008-07-09

    It is generally accepted that good hydrogenation noble and nonnoble metal catalysts such as Pt, Ru, or Ni are not chemoselective for hydrogenation of nitro groups in substituted aromatic molecules. We have found that it is possible to transform nonchemoselective into highly chemoselective metal catalysts by controlling the coordination of metal surface atoms while introducing a cooperative effect between the metal and a properly selected support. Thus, highly chemoselective and general hydrogenation Pt, Ru, and Ni catalysts can be prepared by generating nanosized crystals of the metals on the surface of a TiO 2 support and decorating the exposed (111) and (100) crystal faces by means of a simple catalyst activation procedure. By doing this, it has been possible to change the relative rate for hydrogenating competitive groups present in the molecule by almost 2 orders of magnitude, increasing the chemoselectivity from less than 1% to more than 95%.

  14. SELECTIVE HYDROGENATION OF CINNAMALDEHYDE WITH Pt AND Pt-Fe CATALYSTS: EFFECTS OF THE SUPPORT

    Directory of Open Access Journals (Sweden)

    A.B. da Silva

    1998-06-01

    Full Text Available Low-temperature reduced TiO2-supported Pt and Pt-Fe catalysts are much more active and selective for the liquid–phase hydrogenation of cinnamaldehyde to unsaturated cinnamyl alcohol than the corresponding carbon-supported catalysts. High-temperature reduced catalysts, where the SMSI effect should be present, are almost inactive for this reaction. There is at present no definitive explanation for this effect but an electronic metal-support interaction is most probably involved.

  15. Inorganic compounds and materials as catalysts for oxidations with aqueous hydrogen peroxide

    NARCIS (Netherlands)

    Nardello, veronique; Aubry, Jean-Marie; De Vos, Dirk E.; Neumann, Ronny; Adam, Waldemar; Zhang, Rui; ten Elshof, Johan E.; Witte, Peter T.; Alsters, Paul L.

    2006-01-01

    This paper reviews our work on oxidations with aqueous hydrogen peroxide catalyzed by inorganic catalysts devoid of organic ligands. In the first part of the review, the use of the [WZn3(ZnW9O34)2]12− “sandwich” polyoxometalate as a multi-purpose oxidation catalyst is described. Attention is paid to

  16. Catalysts for initiating the hydrogen-oxygen reaction at 78 K.

    Science.gov (United States)

    Jennings, T. J.; Voge, H. H.; Armstrong, W. E.

    1972-01-01

    Catalysts for initiating reaction of hydrogen with oxygen in gas mixtures at temperatures down to 78 K (-195 C) were sought. A rising-temperature reactor was used for detecting onset of reaction. The platinum metals, especially iridium, platinum, and ruthenium, were the most active. With high concentrations of iridium on an alumina support, reaction initiation was observed at -195 C for a helium stream containing 3% hydrogen and 1% oxygen. Best results were obtained when the catalyst had been preheated in hydrogen and cooled in a hydrogen environment before being contacted with oxygen-containing gas. The initiation is interpreted to be the result of transient phenomena which occur when a hydrogen-oxygen mixture contacts an active catalyst. Chemisorption of oxygen and formation of some water, along with water adsorption on the support, serve to raise the temperature to a point where true catalysis can proceed.

  17. The Integration of a Structural Water Gas Shift Catalyst with a Vanadium Alloy Hydrogen Transport Device

    Energy Technology Data Exchange (ETDEWEB)

    Barton, Thomas; Argyle, Morris; Popa, Tiberiu

    2009-06-30

    component of conventional high temperature water gas shift iron oxide based catalysts. The catalysts contained Fe-Al-Cr-Cu-O and were synthesized by co-precipitation. A series of catalysts were prepared with 5 to 50 wt% Al2O3, with 8 wt% Cr2O3, 4 wt% CuO, and the balance Fe2O3. All of the catalysts were compared to a reference WGS catalyst (88 wt% FeOx, 8 wt% Cr2O3, and 4 wt% CuO) with no alumina. Alumina addition to conventional high temperature water gas shift catalysts at concentrations of approximately 15 wt% increased CO conversion rates and increase thermal stability. A series of high temperature water gas shift catalysts containing iron, chromia, and copper oxides were prepared with small amounts of added ceria in the system Fe-Cr-Cu-Ce-O. The catalysts were also tested kinetically under WGS conditions. 2-4 wt% ceria addition (at the expense of the iron oxide content) resulted in increased reaction rates (from 22-32% higher) compared to the reference catalyst. The project goal of a 10,000 liter per day WGS-membrane reactor was achieved by a device operating on coal derived syngas containing significant amounts of carbon monoxide and hydrogen sulfide. The membrane flux was equivalent to 52 scfh/ft2 based on a 600 psi syngas inlet pressure and corresponded to membranes costing $191 per square foot. Over 40 hours of iv exposure time to syngas has been achieved for a double membrane reactor. Two modules of the Chart reactor were tested under coal syngas for over 75 hours with a single module tested for 50 hours. The permeance values for the Chart membranes were similar to the REB reactor though total flux was reduced due to significantly thicker membranes. Overall testing of membrane reactors on coal derived syngas was over 115 hours for all reactors tested. Testing of the REB double membrane device exceeded 40 hours. Performance of the double membrane reactor has been similar to the results for the single reactor with good maintenance of flux even after these long

  18. Novel Hydrophobic Pt/Inorganic Catalyst Used in Hydrogen Isotope Exchange Reaction

    Directory of Open Access Journals (Sweden)

    JIA Qing-qing1;HU Shi-lin1;FENG Xiao-yan2;LIU Ya-ming1

    2016-11-01

    Full Text Available To improve the performance of hydrophobic catalyst and extend its using range, this research adopted the porous columnar inorganic carriers (ø=5 mm to prepare the hydrophobic catalyst used in hydrogen isotopes exchange reaction, the hydrophilic carriers became hydrophobic with the nanostructured CeO2 coating and the catalyst were then fabricated by convenient impregnation method. The samples were characterized by XRD、SEM、EDX、XPS and CO adsorption. The catalytic activity were tested through catalytic exchange reaction between hydrogen and saturated water vapor to investigate the effect of micro structured CeO2 on the catalyst properties. It turned out that the nano-CeO2 coating could build favorable hydrophobic environment for the catalysts and had almost no influence on the pore structure properties of carriers. Although the hydrophobic coating would lead to the decrease of Pt particle dispersion and metallic Pt content, it could make the Pt particles mostly deposit on the surface layer of the catalysts, which would make more Pt particle participate in the reaction at the same time. The catalytic activity of the novel Pt/inorganic catalyst could reach to 80% of the mature Pt/organic catalyst. After being flushed by water for 12 weeks, the catalytic activity of Pt/inorganic catalyst decreased less than 5%. The novel hydrophobic catalyst with good activity and stability was practical and had great application prospects.

  19. Support Screening Studies on the Hydrogenation of Levulinic Acid to γ-Valerolactone in Water Using Ru Catalysts

    Directory of Open Access Journals (Sweden)

    Anna Piskun

    2016-08-01

    Full Text Available γ-Valerolactone (GVL has been identified as a sustainable platform chemical for the production of carbon-based chemicals. Here we report a screening study on the hydrogenation of levulinic acid (LA to GVL in water using a wide range of ruthenium supported catalysts in a batch set-up (1 wt. % Ru, 90 °C, 45 bar of H2, 2 wt. % catalyst on LA. Eight monometallic catalysts were tested on carbon based(C, carbon nanotubes (CNT and inorganic supports (Al2O3, SiO2, TiO2, ZrO2, Nb2O5 and Beta-12.5. The best result was found for Ru/Beta-12.5 with almost quantitative LA conversion (94% and 66% of GVL yield after 2 h reaction. The remaining product was 4-hydroxypentanoic acid (4-HPA. Catalytic activity for a bimetallic RuPd/TiO2 catalyst was by far lower than for the monometallic Ru catalyst (9% conversion after 2 h. The effects of relevant catalyst properties (average Ru nanoparticle size, Brunauer-Emmett-Teller (BET surface area, micropore area and total acidity on catalyst activity were assessed.

  20. Powdered hydrogenation catalysts. An evaluation and characterization by thermal analysis and ESCA

    Energy Technology Data Exchange (ETDEWEB)

    Kosak, J.R.; Duch, M.W.

    1979-01-01

    An evaluation and characterization by thermal analysis and ESCA showed that both techniques are excellent tools for screening such catalysts, e.g., carbon-supported platinum (1, 4, or 5Vertical Bar3<) or palladium (5Vertical Bar3<) tested in the liquid-phase, batch hydrogenation of p-nitrotoluene at 120/sup 0/C and 500 psig hydrogen. Thermal analysis, a chemisorption technique combined with pressure differential scanning calorimetry, affords a fast, practical means for monitoring the reproducibility of both unreduced and reduced catalysts and yields direct information on catalyst behavior in the presence of hydrogen. ESCA measures relative metal dispersion and permits the evaluation of completeness of reduction in those catalysts after prereduction. The combination of the two techniques provides comparison data about metal dispersion on the support and information on the chemical state of the metal, the latter being particularly useful for characterizing catalyst selectivity. For unreduced or completely reduced catalysts, both techniques give similar hydrogenation performance predictions, but for prereduced catalysts with only partial metal conversion to the zero oxidation state, ESCA yields more reliable data.

  1. Hydrogen Production Enhancement Using a Stratified Catalyst Bed in Reforming Systems

    Science.gov (United States)

    Richards, Nadia Olivia

    An investigation was conducted for a stratified catalyst arrangement for methanol reforming. The motivation for the stratified system is to strategically place different catalysts within the reactor so that the reaction will progress according to the catalyst selectivity. This will allow the reduction of the unwanted intermediates and serves to improve the overall hydrogen product concentration. The stratified arrangement consisted of a platinum group metal (PGM) catalyst, along with a commercially available Cu/ZnO/Al2O 3 water gas shift (WGS) catalyst. The system was experimentally investigated under different test conditions by varying the flow rate, oxygen-to-methanol ratio, and the packed length of the downstream WGS section. From these experiments the effects of each variable were quantified for their influence on the conversion and hydrogen yield. The oxidation reactions were carried out on the PGM catalyst, causing internal heating of the downstream WGS packed bed. The supplied heat keeps the WGS catalyst active to reform and shift the final products into a hydrogen-rich composition. Conversion increases of 30% were possible within one added section of WGS catalyst, with two sections achieving full conversion. This behavior can be modeled as a first order response from which a characteristic WGS length can be determined and used as a descriptive parameter to compare stratified systems. Overall, this study is expected to provide a basic analysis, and contribute to the improvement of reformer design for better fuel processing system performance.

  2. Confinement dependence of electro-catalysts for hydrogen evolution from water splitting

    Directory of Open Access Journals (Sweden)

    Mikaela Lindgren

    2014-02-01

    Full Text Available Density functional theory is utilized to articulate a particular generic deconstruction of the electrode/electro-catalyst assembly for the cathode process during water splitting. A computational model was designed to determine how alloying elements control the fraction of H2 released during zirconium oxidation by water relative to the amount of hydrogen picked up by the corroding alloy. This model is utilized to determine the efficiencies of transition metals decorated with hydroxide interfaces in facilitating the electro-catalytic hydrogen evolution reaction. A computational strategy is developed to select an electro-catalyst for hydrogen evolution (HE, where the choice of a transition metal catalyst is guided by the confining environment. The latter may be recast into a nominal pressure experienced by the evolving H2 molecule. We arrived at a novel perspective on the uniqueness of oxide supported atomic Pt as a HE catalyst under ambient conditions.

  3. Volcano Plot for Bimetallic Catalysts in Hydrogen Generation by Hydrolysis of Sodium Borohydride

    Science.gov (United States)

    Koska, Anais; Toshikj, Nikola; Hoett, Sandra; Bernaud, Laurent; Demirci, Umit B.

    2017-01-01

    In the field of "hydrogen energy", sodium borohydride (NaBH[subscript 4]) is a potential hydrogen carrier able to release H[subscript 2] by hydrolysis in the presence of a metal catalyst. Our laboratory experiment focuses on this. It is intended for thirdyear undergraduate students in order to have hands-on laboratory experience through…

  4. An effective low Pd-loading catalyst for hydrogen generation from formic acid

    DEFF Research Database (Denmark)

    Huang, Yunjie; Xu, Junlei; Ma, Xin

    2017-01-01

    As an interesting hydrogen carrier, formic acid is bio-renewable, non-toxic and available in the liquid state at room temperature. The development of active and low-cost catalyst is of significance for hydrogen generation from formic acid. In this study, both a relatively cheap metal (Ag...

  5. Catalysts for selective oxidation of ammonia in a gas containing hydrogen

    DEFF Research Database (Denmark)

    2015-01-01

    The invention contributes to a cost effective way to solve the problem of trace ammonia removal from a hydrogen and nitrogen containing gas. The set of catalysts of the invention selectively oxidised ammonia in ppm concentration even in gas mixtures containing hydrogen gas in concentrations...

  6. Catalysts for selective oxidation of ammonia in a gas containing hydrogen

    DEFF Research Database (Denmark)

    2014-01-01

    The invention contributes to a cost effective way to solve the problem of trace ammonia removal from hydrogen containing gas. The set of catalysts of the invention selectively oxidised ammonia in ppm concentration even in gas mixture containing hydrogen gas in concentration of three orders...

  7. Hydrogenation of Levulinic Acid over Nickel Catalysts Supported on Aluminum Oxide to Prepare γ-Valerolactone

    Directory of Open Access Journals (Sweden)

    Jie Fu

    2015-12-01

    Full Text Available Four types of nickel catalysts supported on aluminum oxide (Ni/Al2O3 with different nickel loadings were synthesized using the co-precipitation method and were used for the hydrogenation of levulinic acid (LA to prepare γ-valerolactone (GVL. The synthesized Ni/Al2O3 catalysts exhibited excellent catalytic activity in dioxane, and the activity of the catalysts was excellent even after being used four times in dioxane. The catalytic activity in dioxane as a solvent was found to be superior to the activity in water. Nitrogen physisorption, X-ray diffraction, and transmission electron microscopy were employed to characterize the fresh and used catalysts. The effects of the nickel loading, temperature, hydrogen pressure, and substrate/catalyst ratio on the catalytic activity were investigated.

  8. Two-phase model of hydrogen transport to optimize nanoparticle catalyst loading for hydrogen evolution reaction

    DEFF Research Database (Denmark)

    Kemppainen, Erno; Halme, Janne; Hansen, Ole

    2016-01-01

    With electrocatalysts it is important to be able to distinguish between the effects of mass transport and reaction kinetics on the performance of the catalyst. When the hydrogen evolution reaction (HER) is considered, an additional and often neglected detail of mass transport in liquid...... the gas volume fraction is sufficiently high to facilitate H2 transfer to bubbles within a distance shorter than the diffusion layer thickness. At current densities below about 40 mA/cm2 the model reduces to an analytical approximation that has characteristics similar to the diffusion of H2. At higher...... current densities the increase in the gas volume fraction makes the H2 surface concentration nonlinear with respect to the current density. Compared to the typical diffusion layer model, our model is an extension that allows more detailed studies of reaction kinetics and mass transport in the electrolyte...

  9. High volume hydrogen production from the hydrolysis of sodium borohydride using a cobalt catalyst supported on a honeycomb matrix

    Science.gov (United States)

    Marchionni, Andrea; Bevilacqua, Manuela; Filippi, Jonathan; Folliero, Maria G.; Innocenti, Massimo; Lavacchi, Alessandro; Miller, Hamish A.; Pagliaro, Maria V.; Vizza, Francesco

    2015-12-01

    Hydrogen storage and distribution will be two very important aspects of any renewable energy infrastructure that uses hydrogen as energy vector. The chemical storage of hydrogen in compounds like sodium borohydride (NaBH4) could play an important role in overcoming current difficulties associated with these aspects. Sodium borohydride is a very attractive material due to its high hydrogen content. In this paper, we describe a reactor where a stable cobalt based catalyst supported on a commercial Cordierite Honeycomb Monolith (CHM) is employed for the hydrolysis of alkaline stabilized NaBH4 (SBH) aqueous solutions. The apparatus is able to operate at up to 5 bar and 130 °C, providing a hydrogen generation rate of up to 32 L min-1.

  10. Hydrogen production from bio-fuels using precious metal catalysts

    Science.gov (United States)

    Pasel, Joachim; Wohlrab, Sebastian; Rotov, Mikhail; Löhken, Katrin; Peters, Ralf; Stolten, Detlef

    2017-11-01

    Fuel cell systems with integrated autothermal reforming unit require active and robust catalysts for H2 production. Thus, an experimental screening of catalysts for autothermal reforming of commercial biodiesel fuel was performed. Catalysts consisted of a monolithic cordierite substrate, an oxide support (γ-Al2O3) and Pt, Ru, Ni, PtRh and PtRu as active phase. Experiments were run by widely varying the O2/C and H2O/C molar ratios at different gas hourly space velocities. Fresh and aged catalysts were characterized by temperature programmed methods and thermogravimetry to find correlations with catalytic activity and stability.

  11. Hydrogen production from bio-fuels using precious metal catalysts

    Directory of Open Access Journals (Sweden)

    Pasel Joachim

    2017-01-01

    Full Text Available Fuel cell systems with integrated autothermal reforming unit require active and robust catalysts for H2 production. Thus, an experimental screening of catalysts for autothermal reforming of commercial biodiesel fuel was performed. Catalysts consisted of a monolithic cordierite substrate, an oxide support (γ-Al2O3 and Pt, Ru, Ni, PtRh and PtRu as active phase. Experiments were run by widely varying the O2/C and H2O/C molar ratios at different gas hourly space velocities. Fresh and aged catalysts were characterized by temperature programmed methods and thermogravimetry to find correlations with catalytic activity and stability.

  12. Development of Non-Noble Metal Ni-Based Catalysts for Dehydrogenation of Methylcyclohexane

    KAUST Repository

    Al-ShaikhAli, Anaam H.

    2016-11-30

    Liquid organic chemical hydride is a promising candidate for hydrogen storage and transport. Methylcyclohexane (MCH) to toluene (TOL) cycle has been considered as one of the feasible hydrogen carrier systems, but selective dehydrogenation of MCH to TOL has only been achieved using the noble Pt-based catalysts. The aim of this study is to develop non-noble, cost-effective metal catalysts that can show excellent catalytic performance, mainly maintaining high TOL selectivity achievable by Pt based catalysts. Mono-metallic Ni based catalyst is a well-known dehydrogenation catalyst, but the major drawback with Ni is its hydrogenolysis activity to cleave C-C bonds, which leads to inferior selectivity towards dehydrogenation of MCH to TOL. This study elucidate addition of the second metal to Ni based catalyst to improve the TOL selectivity. Herein, ubiquitous bi-metallic nanoparticles catalysts were investigated including (Ni–M, M: Ag, Zn, Sn or In) based catalysts. Among the catalysts investigated, the high TOL selectivity (> 99%) at low conversions was achieved effectively using the supported NiZn catalyst under flow of excess H2. In this work, a combined study of experimental and computational approaches was conducted to determine the main role of Zn over Ni based catalyst in promoting the TOL selectivity. A kinetic study using mono- and bimetallic Ni based catalysts was conducted to elucidate reaction mechanism and site requirement for MCH dehydrogenation reaction. The impact of different reaction conditions (feed compositions, temperature, space velocity and stability) and catalyst properties were evaluated. This study elucidates a distinctive mechanism of MCH dehydrogenation to TOL reaction over the Ni-based catalysts. Distinctive from Pt catalyst, a nearly positive half order with respect to H2 pressure was obtained for mono- and bi-metallic Ni based catalysts. This kinetic data was consistent with rate determining step as (somewhat paradoxically) hydrogenation

  13. The Effect of Catalyst Support on the Decomposition of Methane to Hydrogen and Carbon

    Directory of Open Access Journals (Sweden)

    Sharif Hussein Sharif Zein Abdul Rahman Mohamed

    2012-10-01

    Full Text Available Decomposition of methane into carbon and hydrogen over Cu/Ni supported catalysts was investigated. The catalytic activities and the lifetimes of the catalysts were studied. Cu/Ni supported on TiO2 showed high activity and long lifetime for the reaction. Transmission electron microscopy (TEM studies revealed the relationship between the catalyst activity and the formation of the filamentous carbon over the catalyst after methane decomposition. While different types of filamentous carbon formed on the various Cu/Ni supported catalysts, an attractive carbon nanotubes was observed in the Cu/Ni supported on TiO2. Key Words:  Methane decomposition, carbon nanotube, Cu/Ni supported catalysts.

  14. Ammonia treated Mo/AC catalysts for CO hydrogenation with ...

    Indian Academy of Sciences (India)

    A series of ammonia treated Mo/Activated Carbon (AC) catalysts were synthesized by wet impregnation method by nominal incorporation of 5, 10 and 15 wt% of molybdenum. The calcined catalysts (500◦C, 4 h, N₂ flow) were subjected to a stepwise ammonia treatment at temperatures from 25 up to 700◦C. This work ...

  15. Hydrogen sulphate-based ionic liquid-assisted electro-polymerization of PEDOT catalyst material for high-efficiency photoelectrochemical solar cells

    OpenAIRE

    Carbas, Buket Bezgin; Gulen, Mahir; Tolu, Merve Celik; Sonmezoglu, Savas

    2017-01-01

    This work reports the facile, one-step electro-polymerization synthesis of poly (3,4-ethylenedioxythiophene) (PEDOT) using a 1-ethyl-3-methylimidazolium hydrogen sulphate (EMIMHSO4) ionic liquid (IL) and, for the first time its utilization as a counter electrode (CE) in dye-sensitized solar cells (DSSCs). Using the IL doped PEDOT as CE, we effectively improve the solar cell efficiency to as high as 8.52%, the highest efficiency reported in 150 mC/cm2 charge capacity, an improvement of ~52% ov...

  16. Synthesis of a Novel ZnMoS4 Photo-catalyst and Its Performance for Photo-catalytic Production of Hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Huirong Liang; Guanjie Liu; Yaojun Zhang; Liejin Guo [State Key Laboratory of Multiphase Flow in Power Engineering, School of Energy and Power Engineering, Xian Jiaotong University, 710049, Xian, (China)

    2006-07-01

    The production of hydrogen by photo-catalytic decomposition of water using zinc tetra-thio-molybdate catalyst was studied. Zinc tetra-thio-molybdate catalyst was prepared by coprecipitation and hydrothermal method based on ZnSO{sub 4} and self-prepared [NH{sub 4}]{sub 2}MoS{sub 4} crystal. It was characterized by XRD, XRF, BET and UV-Vis spectra. The photo-catalytic activities of the catalysts were ascertained by the production of hydrogen in an aqueous Na{sub 2}S-Na{sub 2}SO{sub 3} solution under the ultraviolet and visible light irradiation. It was observed that the photo-catalysts showed the visible-light photo-catalytic activity, and the ZnMoS{sub 4} photo-catalyst prepared under hydrothermal condition for about 24 h had the highest activity. (authors)

  17. Carbon-supported platinum alloy catalysts for phenol hydrogenation for making industrial chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Srinivas, S.T.; Song, C.

    1999-07-01

    Phenol is available in large quantities in liquids derived from coal and biomass. Phenol hydrogenation is an industrially important reaction to produce cyclohexanone and cyclohexanol. Cyclohexane, cyclohexene and benzene are obtained as minor products in this reaction. Cyclohexanone is an important intermediate in the production of caprolactam for nylon 6 and cyclohexanol for adipic acid production. In USA, cyclohexanol and cyclohexanone are produced by benzene hydrogenation to cyclohexane over nickel or noble metal catalysts, followed by oxidation of cyclohexane to produce a mixture of cyclohexanol and cyclohexanone. Then cyclohexanol is dehydrogenated in the presence of Cu-Zn catalyst to cyclohexanone. Usually phenol hydrogenation is also carried out by using Ni catalyst in liquid phase. However, a direct single-step vapor phase hydrogenation of phenol to give cyclohexanone selectively is more advantageous in terms of energy savings and process economics, since processing is simplified and the endothermic step of cyclohexanol dehydrogenation can be avoided, as demonstrated by Montedipe and Johnson Matthey using promoted Pd/Al{sub 2}O{sub 3} catalyst. While it is not the purpose of this paper to dwell on the relative merits of these routes, it is necessary to mention that while using monometallic catalysts, generally the problem of catalyst deactivation of sintering as well as coking is frequently encountered. Addition and alloying of noble metal (e.g. Pt) with a second metal can result in a catalyst with better selectivity and activity in the reaction which is more resistant to deactivation. This paper presents the results on the single-step vapor phase hydrogenation of phenol over carbon-supported Pt-M (M=Cr, V, Zr) alloy catalysts to yield mainly cyclohexanone or cyclohexanol.

  18. Electric field tuned MoS2/metal interface for hydrogen evolution catalyst from first-principles investigations

    Science.gov (United States)

    Ling, F. L.; Zhou, T. W.; Liu, X. Q.; Kang, W.; Zeng, W.; Zhang, Y. X.; Fang, L.; Lu, Y.; Zhou, M.

    2018-01-01

    Understanding the interfacial properties of catalyst/substrate is crucial for the design of high-performance catalyst for important chemical reactions. Recent years have witnessed a surge of research in utilizing MoS2 as a promising electro-catalyst for hydrogen production, and field effect has been employed to enhance the activity (Wang et al 2017 Adv. Mater. 29, 1604464; Yan et al 2017 Nano Lett. 17, 4109–15). However, the underlying atomic mechanism remains unclear. In this paper, by using the prototype MoS2/Au system as a probe, we investigate effects of external electric field on the interfacial electronic structures via density functional theory (DFT) based first-principles calculations. Our results reveal that although there is no covalent interaction between MoS2 overlayer and Au substrate, an applied electric field efficiently adjusts the charge transfer between MoS2 and Au, leading to tunable Schottky barrier type (n-type to p-type) and decrease of barrier height to facilitate charge injection. Furthermore, we predict that the adsorption energy of atomic hydrogen on MoS2/Au to be readily controlled by electric field to a broad range within a modest magnitude of field, which may benefit the performance enhancement of hydrogen evolution reaction. Our DFT results provide valuable insight into the experimental observations and pave the way for future understanding and control of catalysts in practice, such as those with vacancies, defects, edge states or synthesized nanostructures.

  19. Selective production of oxygenates from CO2 hydrogenation over mesoporous silica supported Cu-Ga nanocomposite catalyst

    KAUST Repository

    Huang, Kuo-Wei

    2017-11-23

    Carbon dioxide hydrogenation to oxygenates (methanol and dimethyl ether (DME)) was investigated over bifunctional supported copper catalysts promoted with gallium (Ga). Supported Cu-Ga nanocomposite catalysts were characterized by X-ray diffraction, transmission electron microscopy with energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and H2 temperature programmed reduction. In comparison with Cu-SBA-15 based catalysts, Ga promoted catalysts prepared by the urea deposition method (CuGa/SBA-15-UDP) was found active and selective for CO2 hydrogenation to oxygenates. The use of Ga as the promoter showed increased acidic sites as confirmed by the NH3-TPD, Pyridine-IR and 2,6-lutidine-IR studies. The favorable effect of Ga on CO2 conversion and selectivity to oxygenate may come from the strong interaction of Ga with silica, which is responsible for the enhanced metal surface area, formation of nanocomposite and metal dispersion. Notably, incorporation of Ga to Cu/SiO2 showed a several-fold higher rate for methanol formation (13.12 mol/gCu·sec) with a reasonable rate for the DME formation (2.15 mol/gCu·sec) as compared to those of Cu/SiO2 catalysts.

  20. Silver-palladium catalysts for the direct synthesis of hydrogen peroxide

    Science.gov (United States)

    Khan, Zainab; Dummer, Nicholas F.; Edwards, Jennifer K.

    2017-11-01

    A series of bimetallic silver-palladium catalysts supported on titania were prepared by wet impregnation and assessed for the direct synthesis of hydrogen peroxide, and its subsequent side reactions. The addition of silver to a palladium catalyst was found to significantly decrease hydrogen peroxide productivity and hydrogenation, but crucially increase the rate of decomposition. The decomposition product, which is predominantly hydroxyl radicals, can be used to decrease bacterial colonies. The interaction between silver and palladium was characterized using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and temperature programmed reduction (TPR). The results of the TPR and XPS indicated the formation of a silver-palladium alloy. The optimal 1% Ag-4% Pd/TiO2 bimetallic catalyst was able to produce approximately 200 ppm of H2O2 in 30 min. The findings demonstrate that AgPd/TiO2 catalysts are active for the synthesis of hydrogen peroxide and its subsequent decomposition to reactive oxygen species. The catalysts are promising for use in wastewater treatment as they combine the disinfectant properties of silver, hydrogen peroxide production and subsequent decomposition. This article is part of a discussion meeting issue 'Providing sustainable catalytic solutions for a rapidly changing world'.

  1. A DFT study on the effect of hydrogen in ethylene and propylene polymerization using a Ti-based heterogeneous Ziegler–Natta catalyst

    KAUST Repository

    Bahri-Laleh, Naeimeh

    2012-11-01

    Hydrogenolysis of a series of model Ziegler-Natta (Z-N) catalysts to form Ti-H bond was studied within DFT. We focused our efforts on Ti species attached to the (110) lateral cut of MgCl 2 which exist as different centres including Ti-C 2H 5, Ti-CH 2CH(CH 3) 2, and Ti-CH(CH 3)CH 2CH 3 in ethylene and propylene polymerization. In the next step, reactivity of Ti-H bond towards ethylene and propylene (1,2- and 2,1-) insertion was investigated. Results showed that insertion of ethylene and propylene into Ti-H bond has less barrier, in comparison with their insertion in Ti-C bond, however, ethylene and propylene 2,1- insertion lead to Ti-C 2H 5 and Ti-CH(CH 3) 2 centres respectively, which were stable due to strong β-agostic interactions. Finally, by considering different possible reactions of active centre, activity depression in ethylene polymerization and activity increase in propylene polymerization were explained in detail. © 2012 Elsevier B.V.

  2. Magnetic Fe@g‑C3N4: A Photoactive Catalyst for the Hydrogenation of Alkenes and Alkynes

    Data.gov (United States)

    U.S. Environmental Protection Agency — A photoactive catalyst, Fe@g-C3N4, has been developed for the hydrogenation of alkenes and alkynes using hydrazine hydrate as a source of hydrogen. The magnetically...

  3. Production of renewable hydrogen from aqueous-phase reforming of glycerol over Pt catalysts supported on different oxides

    Energy Technology Data Exchange (ETDEWEB)

    Menezes, Andre O. [Instituto Nacional de Tecnologia/MCT, Laboratorio de Catalise, Av. Venezuela 82/507, Rio de Janeiro/RJ 22081-312 (Brazil); Instituto Militar de Engenharia, Praca General Tiburcio, 80 Praia Vermelha, Rio de Janeiro/RJ 22290-270 (Brazil); Rodrigues, Michelly T.; Zimmaro, Adriana; Fraga, Marco A. [Instituto Nacional de Tecnologia/MCT, Laboratorio de Catalise, Av. Venezuela 82/507, Rio de Janeiro/RJ 22081-312 (Brazil); Borges, Luiz E.P. [Instituto Militar de Engenharia, Praca General Tiburcio, 80 Praia Vermelha, Rio de Janeiro/RJ 22290-270 (Brazil)

    2011-02-15

    Aqueous-phase reforming of oxygenated hydrocarbons for hydrogen production presents several advantages as feed molecules can be easily found in a wide range of biomass, there is no need for its vaporization and the process allows thorough exploitation of the environmental benefits of using hydrogen as an energy carrier. The use of glycerol in particular is motivated due to its availability as a consequence of increasing biodiesel production worldwide. In this contribution, the performance of Pt-based catalysts supported on different oxides (Al{sub 2}O{sub 3}, ZrO{sub 2}, MgO and CeO{sub 2}) is studied on glycerol reforming. All catalysts led to a hydrogen-rich gas phase. However, a good potential activity with high production of hydrogen and low concentration of undesired hydrocarbons was accomplished over the catalysts supported on MgO and ZrO{sub 2}. The high electron donating character of such oxides indicates the influence of the nature of the support in catalytic performance for glycerol reforming. (author)

  4. Interstitial modification of palladium nanoparticles with boron atoms as a green catalyst for selective hydrogenation

    Science.gov (United States)

    Chan, Chun Wong Aaron; Mahadi, Abdul Hanif; Li, Molly Meng-Jung; Corbos, Elena Cristina; Tang, Chiu; Jones, Glenn; Kuo, Winson Chun Hsin; Cookson, James; Brown, Christopher Michael; Bishop, Peter Trenton; Tsang, Shik Chi Edman

    2014-12-01

    Lindlar catalysts comprising of palladium/calcium carbonate modified with lead acetate and quinoline are widely employed industrially for the partial hydrogenation of alkynes. However, their use is restricted, particularly for food, cosmetic and drug manufacture, due to the extremely toxic nature of lead, and the risk of its leaching from catalyst surface. In addition, the catalysts also exhibit poor selectivities in a number of cases. Here we report that a non-surface modification of palladium gives rise to the formation of an ultra-selective nanocatalyst. Boron atoms are found to take residence in palladium interstitial lattice sites with good chemical and thermal stability. This is favoured due to a strong host-guest electronic interaction when supported palladium nanoparticles are treated with a borane tetrahydrofuran solution. The adsorptive properties of palladium are modified by the subsurface boron atoms and display ultra-selectivity in a number of challenging alkyne hydrogenation reactions, which outclass the performance of Lindlar catalysts.

  5. Self-assembling biomolecular catalysts for hydrogen production.

    Science.gov (United States)

    Jordan, Paul C; Patterson, Dustin P; Saboda, Kendall N; Edwards, Ethan J; Miettinen, Heini M; Basu, Gautam; Thielges, Megan C; Douglas, Trevor

    2016-02-01

    The chemistry of highly evolved protein-based compartments has inspired the design of new catalytically active materials that self-assemble from biological components. A frontier of this biodesign is the potential to contribute new catalytic systems for the production of sustainable fuels, such as hydrogen. Here, we show the encapsulation and protection of an active hydrogen-producing and oxygen-tolerant [NiFe]-hydrogenase, sequestered within the capsid of the bacteriophage P22 through directed self-assembly. We co-opted Escherichia coli for biomolecular synthesis and assembly of this nanomaterial by expressing and maturing the EcHyd-1 hydrogenase prior to expression of the P22 coat protein, which subsequently self assembles. By probing the infrared spectroscopic signatures and catalytic activity of the engineered material, we demonstrate that the capsid provides stability and protection to the hydrogenase cargo. These results illustrate how combining biological function with directed supramolecular self-assembly can be used to create new materials for sustainable catalysis.

  6. Towards a rational design of ruthenium CO2 hydrogenation catalysts by Ab initio metadynamics.

    Science.gov (United States)

    Urakawa, Atsushi; Iannuzzi, Marcella; Hutter, Jürg; Baiker, Alfons

    2007-01-01

    Complete reaction pathways relevant to CO2 hydrogenation by using a homogeneous ruthenium dihydride catalyst ([Ru(dmpe)2H2], dmpe=Me2PCH2CH2PMe2) have been investigated by ab initio metadynamics. This approach has allowed reaction intermediates to be identified and free-energy profiles to be calculated, which provide new insights into the experimentally observed reaction pathway. Our simulations indicate that CO2 insertion, which leads to the formation of formate complexes, proceeds by a concerted insertion mechanism. It is a rapid and direct process with a relatively low activation barrier, which is in agreement with experimental observations. Subsequent H2 insertion into the formate--Ru complex, which leads to the formation of formic acid, instead occurs via an intermediate [Ru(eta2-H2)] complex in which the molecular hydrogen coordinates to the ruthenium center and interacts weakly with the formate group. This step has been identified as the rate-limiting step. The reaction completes by hydrogen transfer from the [Ru(eta2-H2)] complex to the formate oxygen atom, which forms a dihydrogen-bonded Ru--HHO(CHO) complex. The activation energy for the H2 insertion step is lower for the trans isomer than for the cis isomer. A simple measure of the catalytic activity was proposed based on the structure of the transition state of the identified rate-limiting step. From this measure, the relationship between catalysts with different ligands and their experimental catalytic activities can be explained.

  7. Comparison of cathode catalyst binders for the hydrogen evolution reaction in microbial electrolysis cells

    KAUST Repository

    Ivanov, Ivan

    2017-06-02

    Nafion is commonly used as a catalyst binder in many types of electrochemical cells, but less expensive binders are needed for the cathodes in microbial electrolysis cells (MECs) which are operated in neutral pH buffers, and reverse electrodialysis stacks (RED),which use thermolytic solutions such as ammonium bicarbonate. Six different binders were examined based on differences in ion exchange properties (anionic: Nafion, BPSH20, BPSH40, S-Radel; cationic: Q-Radel; and neutral: Radel, BAEH) and hydrophobicity based on water uptake (0%, Radel; 17–56% for the other binders). BPSH40 had similar performance to Nafion based on steady-state polarization single electrode experiments in a neutral pH phosphate buffer, and slightly better performance in ammonium bicarbonate. Three different Mo-based catalysts were examined as alternatives to Pt, with MoB showing the best performance under steady-state polarization. In MECs, MoB/BPSH40 performed similarly to Pt with Nafion or Radel binders. The main distinguishing feature of the BPSH40 was that it is very hydrophilic, and thus it had a greater water content (56%) than the other binders (0–44%). These results suggest the binders for hydrogen evolution in MECs should be designed to have a high water content without sacrificing ionic or electronic conductivity in the electrode.

  8. Ligand effect in enantioselective hydrogenation on skeletal copper-palladium catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Vedenyapin, A.A.; Kuznetsova, T.I.; Klabunovskii, E.I.

    1987-08-10

    In the continuation of the study of the capacity of skeletal Cu-Pd catalysts modified with RR-tartaric acid and containing no more than 5 at.% Pd, to conduct enantioselective hydrogenation of ethylacetoacetate (EAA) into R-ethyl-..beta..-hydroxybutyrate (R-EHB), they studied this phenomenon in more detail and made the previously obtained data more precise. Pronounced synergism of the asymmetric effect of chiral copper-palladium catalysts related to manifestation of a ligand effect was found.

  9. Renewable hydrogen: carbon formation on Ni and Ru catalysts during ethanol steam-reforming

    DEFF Research Database (Denmark)

    Rass-Hansen, Jeppe; Christensen, Christina Hviid; Sehested, J.

    2007-01-01

    addition was a rapid deactivation of the catalyst due to an enhanced gum carbon formation on the Ni crystals. Contrary to this, the effect of K addition was a prolonged resistance against carbon formation and therefore against deactivation. The Ru catalyst operates better than all the Ni catalysts...... for the production of hydrogen is investigated, along with quantitative and qualitative determinations of carbon formation on the catalysts by TPO and TEM experiments. A Ru/ MgAl2O4 catalyst, a Ni/MgAl2O4 catalyst as well as Ag-and K-promoted Ni/ MgAl2O4 catalysts were studied. The operating temperature was between...... 673 and 873 K, and a 25 vol% ethanol -water mixture was employed. Deactivation of the catalysts by carbon formation is the main obstacle for industrial use of this process. Carbon formation was found to be highly affected by the operating temperature and the choice of catalyst. The effect of Ag...

  10. Effect of chemically reduced palladium supported catalyst on sunflower oil hydrogenation conversion and selectivity

    Directory of Open Access Journals (Sweden)

    Abdulmajid Alshaibani

    2017-02-01

    Full Text Available Catalytic hydrogenation of sunflower oil was studied in order to improve the conversion and to reduce the trans-isomerization selectivity. The hydrogenation was performed using Pd–B/γ-Al2O3 prepared catalyst and Pd/Al2O3 commercial catalyst under similar conditions. The Pd–B/γ-Al2O3 catalyst was prepared by wet impregnation and chemical reduction processes. It was characterized by Brunauer–Emmett–Teller surface area analysis (BET, X-ray powder diffraction (XRD, scanning electron microscopy (SEM, and transmission electron microscopy (TEM. The result of sunflower oil hydrogenation on Pd–B/γ-Al2O3 catalyst showed a 17% higher conversion and a 23% lower trans-isomerization selectivity compared to the commercial Pd/Al2O3 catalyst. The chemical reduction of palladium supported catalyst using potassium borohydride (KBH4 has affected the Pd–B/γ-Al2O3 catalyst’s structure and particle size. These most likely influenced its catalytic performance toward higher conversion and lower trans-isomerization selectivity.

  11. Production of hydrogen for fuel cells by steam reforming of ethanol over supported noble metal catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Liguras, Dimitris K.; Kondarides, Dimitris I.; Verykios, Xenophon E. [Department of Chemical Engineering, University of Patras, GR-26504 Patras (Greece)

    2003-07-25

    The catalytic performance of supported noble metal catalysts for the steam reforming (SR) of ethanol has been investigated in the temperature range of 600-850C with respect to the nature of the active metallic phase (Rh, Ru, Pt, Pd), the nature of the support (Al{sub 2}O{sub 3}, MgO, TiO{sub 2}) and the metal loading (0-5wt.%). It is found that for low-loaded catalysts, Rh is significantly more active and selective toward hydrogen formation compared to Ru, Pt and Pd, which show a similar behavior. The catalytic performance of Rh and, particularly, Ru is significantly improved with increasing metal loading, leading to higher ethanol conversions and hydrogen selectivities at given reaction temperatures. The catalytic activity and selectivity of high-loaded Ru catalysts is comparable to that of Rh and, therefore, ruthenium was further investigated as a less costly alternative. It was found that, under certain reaction conditions, the 5% Ru/Al{sub 2}O{sub 3} catalyst is able to completely convert ethanol with selectivities toward hydrogen above 95%, the only byproduct being methane. Long-term tests conducted under severe conditions showed that the catalyst is acceptably stable and could be a good candidate for the production of hydrogen by steam reforming of ethanol for fuel cell applications.

  12. Hydrogen production by steam reforming of methanol in a micro-channel reactor coated with Cu/ZnO/ZrO 2/Al 2O 3 catalyst

    Science.gov (United States)

    Jeong, Heondo; Kim, Kweon Ill; Kim, Tae Hwan; Ko, Chang Hyun; Park, Hwa Choon; Song, In Kyu

    Hydrogen production by steam reforming of methanol is studied over Cu/Zn-based catalysts (Cu/ZnO, Cu/ZnO/Al 2O 3, Cu/ZnO/ZrO 2/Al 2O 3). Cu/Zn-based catalysts are derived from hydrotalcite-like precursors prepared by a co-precipitation method. The catalysts are characterized by N 2O chemisorption, XRD, and BET surface area measurements. ZrO 2 added to the Cu/Zn-based catalyst enhances copper dispersion on the catalyst surface. Among the catalysts tested, Cu/ZnO/ZrO 2/Al 2O 3 exhibits the highest methanol conversion and the lowest CO concentration in the outlet gas. A micro-channel reactor coated with a Cu/ZnO/ZrO 2/Al 2O 3 catalyst in the presence of an undercoated Al 2O 3 buffer layer exhibits higher methanol conversion and lower CO concentration in the outlet gas than in the absence of an undercoated Al 2O 3 buffer layer. The micro-channel reactor with a undercoated Al 2O 3 buffer layer produces large amounts of hydrogen compared with one without a buffer layer. The undercoated Al 2O 3 buffer layer enhances the adhesion between catalysts and micro-channel walls, which leads to improvement in reactor performance.

  13. Hydrogen generation from decomposition of hydrous hydrazine over Ni-Ir/CeO2 catalyst

    OpenAIRE

    Dai, Hongbin; Zhong, Yujie; Wang, Ping

    2017-01-01

    The synthesis of highly active and selective catalysts is the central issue in the development of hydrous hydrazine (N2H4·H2O) as a viable hydrogen carrier. Herein, we report the synthesis of bimetallic Ni-Ir nanocatalyts supported on CeO2 using a one-pot coprecipitation method. A combination of XRD, HRTEM and XPS analyses indicate that the Ni-Ir/CeO2 catalyst is composed of tiny Ni-Ir alloy nanoparticles with an average size of around 4 nm and crystalline CeO2 matrix. The Ni-Ir/CeO2 catalyst...

  14. TOTAL HYDROGENATION OF BIOMASS-DERIVED FURFURAL OVER RANEY NICKEL-CLAY NANOCOMPOSITE CATALYSTS

    Directory of Open Access Journals (Sweden)

    Rodiansono Rodiansono

    2013-08-01

    Full Text Available Inexpensive Raney Ni-clay composite (R-Ni/clay catalysts exhibited excellent activity and reusability in the total hydrogenation of biomass-derived furfural into tetrahydrofurfuryl alcohol under mild conditions. For the Raney Ni-bentonite (R-Ni/BNT catalysts, the complete reaction was achieved at 393 K, 180 min giving almost 99% yield of tetrahydrofurfuryl alcohol. The R-Ni/BNT catalyst was found to be reusable without any significant loss of activity and selectivity for at least six consecutive runs.

  15. Ceria-based solid catalysts for organic chemistry.

    Science.gov (United States)

    Vivier, Laurence; Duprez, Daniel

    2010-06-21

    Ceria has been the subject of thorough investigations, mainly because of its use as an active component of catalytic converters for the treatment of exhaust gases. However, ceria-based catalysts have also been developed for different applications in organic chemistry. The redox and acid-base properties of ceria, either alone or in the presence of transition metals, are important parameters that allow to activate complex organic molecules and to selectively orient their transformation. Pure ceria is used in several organic reactions, such as the dehydration of alcohols, the alkylation of aromatic compounds, ketone formation, and aldolization, and in redox reactions. Ceria-supported metal catalysts allow the hydrogenation of many unsaturated compounds. They can also be used for coupling or ring-opening reactions. Cerium atoms can be added as dopants to catalytic system or impregnated onto zeolites and mesoporous catalyst materials to improve their performances. This Review demonstrates that the exceptional surface (and sometimes bulk) properties of ceria make cerium-based catalysts very effective for a broad range of organic reactions.

  16. Highly Selective Hydrogenation of Levulinic Acid to gamma-Valerolactone Over Ru/ZrO2 Catalysts

    NARCIS (Netherlands)

    Filiz, Bilge Coskuner; Gnanakumar, Edwin S.; Martinez-Arias, Arturo; Gengler, Regis; Rudolf, Petra; Rothenberg, Gadi; Shiju, N. Raveendran

    We studied the catalytic hydrogenation of levulinic acid over zirconia supported ruthenium catalysts. Four different Ru/ZrO2 catalysts were prepared by different pre-treatments and using different zirconium supports (ZrOx(OH)(4-2x) and ZrO2). Although the final compositions of the catalysts are the

  17. Highly Selective Hydrogenation of Levulinic Acid to γ-Valerolactone Over Ru/ZrO2 Catalysts

    NARCIS (Netherlands)

    Filiz, B.C.; Gnanakumar, E.S.; Martinez-Arias, A.; Gengler, R.; Rudolf, P.; Rothenberg, G.; Shiju, N.R.

    We studied the catalytic hydrogenation of levulinic acid over zirconia supported ruthenium catalysts. Four different Ru/ZrO2 catalysts were prepared by different pre-treatments and using different zirconium supports (ZrOx(OH)4−2x and ZrO2). Although the final compositions of the catalysts are the

  18. The role of nano-Ni catalyst in MgH2 obtained by reactive mechanical milling method for solid hydrogen storage application

    Science.gov (United States)

    Jalil, Zulkarnain; Rahwanto, Adi; Handoko, Erfan; Mustanir

    2017-03-01

    Magnesium (Mg) is regarded as one of the candidate material for absorbing hydrogen, because theoretically, has the ability to absorb hydrogen in the large quantities (7.6 wt%). However, Mg has shortage, namely its kinetic reaction is very slow, it takes time to absorb hydrogen at least 60 minutes with very high operating temperatures (300-400°C). The aim of this study is to improve the hydrogen desorption temperature of Mg-based hydrogen storage material. In this work, we used nano-nickel (Ni) as catalyst in MgH2 and obtained by reactive mechanical milling method. The duration of milling was done in 2 hours (soft milling) with the 2 mol% Ni catalyst and milled under hydrogen atmosphere (10 bar). As the results, small amount of 2 mol% Ni in nanometer scale acts as a suitable catalyst for improvement the kinetics of MgH2 which could absorp 5.5 wt% of hydrogen within 10 minutes at 300°C. It is obvious that small amount has much better as catalyst in nanoparticle size and at the same time allowed to reduce the milling process in short time.

  19. Transfer hydrogenation of olefin from alcohol using a hydrogen-absorbing alloy (CaNi{sub 5}) catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Imamura, H.; Tanaka, T.; Sakata, Y.; Tsuchiya, S. [Yamaguchi Univ., Ube (Japan). Faculty of Engineering

    1999-12-20

    Gas-phase reactions between 2-butene and 2-propanol on a hydrogen-absorbing alloy CaNi{sub 5} have been studied in the temperature range of 393 to 473 K. CaNi{sub 5} showed interesting characteristics as an active catalyst for the transfer hydrogenation of butene from propanol as a hydrogen donor. 2-Propanol was effectively dehydrogenated to yield acetone, in which the dissociated hydrogen was completely absorbed by CaNi{sub 5} to form the metal hydride. When the alloy was hydrided to some extent, butene was effectively hydrogenated by the absorbed hydrogen in the metal hydride to produce butane. The overall reaction was expressed as catalytic transfer hydrogenation through the formation of metal hydride intermediates (CaNi{sub 5}H{sub n}). Catalytic transfer hydrogenation on CaNi{sub 5} occurred at 423 K via hydriding of CaNi{sub 5} by 2-propanol dehydrogenation with subsequent dehydriding for the hydrogenation of 2-butene, rather than the direct reaction between 2-butene and 2-propanol on the alloy. (orig.)

  20. Ruthenium catalysts for hydrogenation of aromatic and aliphatic esters: make use of bidentate carbene ligands.

    Science.gov (United States)

    Westerhaus, Felix A; Wendt, Bianca; Dumrath, Andreas; Wienhöfer, Gerrit; Junge, Kathrin; Beller, Matthias

    2013-06-01

    Committed carbenes: The convenient application of bidentate carbene ligands is described for the hydrogenation of carboxylic acid esters. The ligand precursors are easily synthesized through the dimerization of N-substituted imidazoles with diiodomethane. The catalyst is generated in situ and exhibits good activity and functional group tolerance for the hydrogenation of aromatic and aliphatic carboxylic acid esters. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Kinetic aspect of the promoting action of rhenium in hydrogenation of benzene on alumina-platinum catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Zharkov, B.B.; Grishchenko, A.V.; Evgrashin, V.M.; Klyuchnikova, Z.S.; Polyakov, A.A.; Rubinov, A.Z.; Fedorov, V.S.

    1987-09-10

    Rhenium is one of the most effective promoters used for the modification of industrial reforming catalysts and has been found to raise the hydrogenating activity of platinum/aluminium dioxide catalysts considerably in the conversion of benzene to cyclohexane. The purpose of this paper is to study this effect from the kinetic standpoint. Test procedures are described. The contribution of rhenium to the reaction kinetics was measured by the desorption rate of hydrogen from the catalysts.

  2. Designing Efficient Solar-Driven Hydrogen Evolution Photocathodes Using Semitransparent MoQxCly(Q = S, Se) Catalysts on Si Micropyramids

    KAUST Repository

    Ding, Qi

    2015-09-21

    © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Silicon micropyramids with n+pp+ junctions are demonstrated to be efficient absorbers for integrated solar-driven hydrogen production systems enabling significant improvements in both photocurrent and onset potential. When conformally coated with MoSxCly, a catalyst that has excellent catalytic activity and high optical transparency, the highest photocurrent density for Si-based photocathodes with earth-abundant catalysts is achieved.

  3. Ammonia treated Mo/AC catalysts for CO hydrogenation with ...

    Indian Academy of Sciences (India)

    SHARIF F ZAMAN

    liquid fuels and a variety of chemicals. Syngas can be produced from different carbon containing materials, such as coal, natural gas and biomass by means of gasi- fication and reforming. Syngas can be converted into hydrocarbons, methanol and higher alcohols depending on the type of catalyst used and reaction ...

  4. Enantioselective Claisen Rearrangements with a Hydrogen-Bond Donor Catalyst

    Science.gov (United States)

    Uyeda, Christopher; Jacobsen, Eric N.

    2008-01-01

    N,N′-Diphenylguanidinium ion associated with the non-coorinating BArF counterion is shown to be an effective catalyst for the [3,3]-sigmatropic rearrangement of a variety of substituted allyl vinyl ethers. Highly enantioselective catalytic Claisen rearrangements of ester-substituted allyl vinyl ethers are then documented using a new C2-symmetric guanidinium ion derivative. PMID:18576616

  5. STRONTIUM AS AN EFFICIENT PROMOTER FOR SUPPORTED PALLADIUM HYDROGENATION CATALYSTS

    Science.gov (United States)

    The effect of strontium promotion is studied for a series of supported palladium catalysts such as Pd/zeolite-β, Pd/Al2O3, Pd/SiO2, Pd/hydrotalcite and Pd/MgO. Strontium is found to be an effective promoter for enhancing the metal area, perce...

  6. sup 1 H NMR studies of hydrogen and carbon monoxide chemisorption on the EUROPt-1 catalyst

    CERN Document Server

    Bouyssy, P X

    2001-01-01

    possible carbon monoxide-induced reorganisation of the surface sites available for hydrogen, following a carbon monoxide precoverage above a critical level. It also shows that carbon monoxide blocks hydrogen adsorption but not in the manner expected. No desorption of carbon monoxide was observed with gas phase infrared experiments even at hydrogen coverages approaching saturation. Secondly, to further the understanding of the dynamics of adsorbed hydrogen exchanging between the strongly bound and the weakly bound sites, proton relaxation NMR experiments were undertaken. T sub 1 and T sub 1 subrho measurements were carried out as a function of hydrogen coverage at room temperature and as a function of temperature at fixed hydrogen coverage. These experiments proved to be experimentally challenging and the data obtained do not show a clear enough trend to reach a significant conclusion as was firstly expected. A specially designed sup 1 H NMR probe, capable of holding a large quantity of catalyst sample for in ...

  7. Hydrogen generation from sodium borohydride solution using a ruthenium supported on graphite catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Yan; Dai, Hong-Bin; Ma, Lai-Peng; Wang, Ping; Cheng, Hui-Ming [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2010-04-15

    The catalyst with high activity and durability plays a crucial role in the hydrogen generation systems for the portable fuel cell generators. In the present study, a ruthenium supported on graphite catalyst (Ru/G) for hydrogen generation from sodium borohydride (NaBH{sub 4}) solution is prepared by a modified impregnation method. This is done by surface pretreatment with NH{sub 2} functionalization via silanization, followed by adsorption of Ru (III) ion onto the surface, and then reduced by a reducing agent. The obtained catalyst is characterized by transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS). Very uniform Ru nanoparticles with sizes of about 10 nm are chemically bonded on the graphite surface. The hydrolysis kinetics measurements show that the concentrations of NaBH{sub 4} and NaOH all exert considerable influence on the catalytic activity of Ru/G catalyst towards the hydrolysis reaction of NaBH{sub 4}. A hydrogen generation rate of 32.3 L min{sup -1} g{sup -1} (Ru) in a 10 wt.% NaBH{sub 4} + 5 wt.% NaOH solution has been achieved, which is comparable to other noble catalysts that have been reported. (author)

  8. Hydrogen production by ethanol steam reforming over Cu-Ni supported catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Vizcaino, A.J.; Carrero, A.; Calles, J.A. [Department of Chemical and Environmental Technology, Rey Juan Carlos University, Escuela Superior de Ciencias Experimentales y Tecnologia (ESCET), c/ Tulipan s/n, 28933 Mostoles (Spain)

    2007-07-15

    In the present work, Cu-Ni supported catalysts were tested in ethanol steam reforming reaction. Two commercial amorphous solids (SiO{sub 2} and {gamma}-Al{sub 2}O{sub 3}) and three synthesized materials (MCM-41, SBA-15 and ZSM-5 nanocrystalline) were used as support. A series of Cu-Ni/SiO{sub 2} catalysts with different Cu and Ni content were also prepared. It was found that aluminium containing supports favour ethanol dehydration to ethylene in the acid sites, which in turn, promotes the coke deactivation process. The highest hydrogen selectivity is achieved with the Cu-Ni/SBA-15 catalyst, due to a smaller metallic crystallite size. Nevertheless, the Cu-Ni/SiO{sub 2} catalyst showed the best catalytic performance, since a better equilibrium between high hydrogen selectivity and CO{sub 2}/CO{sub x} ratio is obtained. It was seen that nickel is the phase responsible for hydrogen production in a greater grade, although both CO production and coke deposition are decreased when copper is added to the catalyst. (author)

  9. Tuning the activity of nanoplatelet MoS{sub 2}-based catalyst for efficient hydrogen evolution via electrochemical decoration with Pt nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Jagminas, Arunas, E-mail: jagmin@ktl.mii.lt [State Research Institute Centre for Physical Sciences and Technology, Savanoriu 231, LT-02300 Vilnius (Lithuania); Naujokaitis, Arnas [State Research Institute Centre for Physical Sciences and Technology, Savanoriu 231, LT-02300 Vilnius (Lithuania); Vilnius University, Faculty of Physics, Sauletekio av. 9, LT-10222 Vilnius (Lithuania); Žalnėravičius, Rokas; Jasulaitiene, Vitalija [State Research Institute Centre for Physical Sciences and Technology, Savanoriu 231, LT-02300 Vilnius (Lithuania); Valušis, Gintaras [State Research Institute Centre for Physical Sciences and Technology, Savanoriu 231, LT-02300 Vilnius (Lithuania); Vilnius University, Faculty of Physics, Sauletekio av. 9, LT-10222 Vilnius (Lithuania)

    2016-11-01

    Highlights: • MoS{sub 2}-based nanoplatelet films on Mo substrate by hydrothermal treatment. • Electrochemical decoration of MoS{sub 2} nanoplatelets with Pt nanoparticles. • Ultra-high efficiency of HER at heterostructured electrode surface. - Abstract: This study establishes a novel methodology for increasing the HER activity of the molybdenum substrate covered with amorphous molybdenum sulfide-oxide nano-structured film up to ultra-high level. We show that utilization of such nanoplatelet/nanoflowered film as electrocatalyst for HER in the sulfuric acidic solution cell with Pt anode and Ag/AgCl,KCl reference leads to obvious structural transformations and nice decoration of nanoplatelet edges with few-nm sized Pt nanoparticles. By this way, a surprising HER efficiency attaining ∼160 mA cm{sup −2} current density at −200 mV and ∼260 mA cm{sup −2} at −300 mV vs RHE overpotentials with the onset of reaction close to the one carried out at the bulk Pt electrode was obtained. To the best of our knowledge, these HER characteristics are among the best reported to date for hybrid MoS{sub 2}-based HER electrocatalysts. The results obtained were confirmed by SEM, XPS, XRD, conductive mode AFM and cyclic voltammetry. It is worth noticing that to achieve this synergetic effect only about 0.5 μg cm{sup −2} of Pt is required.

  10. Self-optimizing, highly surface-active layered metal dichalcogenide catalysts for hydrogen evolution

    Science.gov (United States)

    Liu, Yuanyue; Wu, Jingjie; Hackenberg, Ken P.; Zhang, Jing; Wang, Y. Morris; Yang, Yingchao; Keyshar, Kunttal; Gu, Jing; Ogitsu, Tadashi; Vajtai, Robert; Lou, Jun; Ajayan, Pulickel M.; Wood, Brandon C.; Yakobson, Boris I.

    2017-09-01

    Low-cost, layered transition-metal dichalcogenides (MX2) based on molybdenum and tungsten have attracted substantial interest as alternative catalysts for the hydrogen evolution reaction (HER). These materials have high intrinsic per-site HER activity; however, a significant challenge is the limited density of active sites, which are concentrated at the layer edges. Here we unravel electronic factors underlying catalytic activity on MX2 surfaces, and leverage the understanding to report group-5 MX2 (H-TaS2 and H-NbS2) electrocatalysts whose performance instead mainly derives from highly active basal-plane sites, as suggested by our first-principles calculations and performance comparisons with edge-active counterparts. Beyond high catalytic activity, they are found to exhibit an unusual ability to optimize their morphology for enhanced charge transfer and accessibility of active sites as the HER proceeds, offering a practical advantage for scalable processing. The catalysts reach 10 mA cm-2 current density at an overpotential of ˜50-60 mV with a loading of 10-55 μg cm-2, surpassing other reported MX2 candidates without any performance-enhancing additives.

  11. Catalytic Ring Hydrogenation of Benzoic Acid with Supported Transition Metal Catalysts in scCO2

    Directory of Open Access Journals (Sweden)

    Fengyu Zhao

    2007-07-01

    Full Text Available The ring hydrogenation of benzoic acid to cyclohexanecarboxylic acid overcharcoal-supported transition metal catalysts in supercritical CO2 medium has been studiedin the present work. The cyclohexanecarboxylic acid can be produced efficiently insupercritical CO2 at the low reaction temperature of 323 K. The presence of CO2 increasesthe reaction rate and several parameters have been discussed.

  12. Vapor Phase Hydrogenation of Nitrobenzene to Aniline Over Carbon Supported Ruthenium Catalysts.

    Science.gov (United States)

    Srikanth, Chakravartula S; Kumar, Vanama Pavan; Viswanadham, Balaga; Srikanth, Amirineni; Chary, Komandur V R

    2015-07-01

    A series of Ru/Carbon catalysts (0.5-6.0 wt%) were prepared by impregnation method. The catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), temperature programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), CO-chemisorption, surface area and pore-size distribution measurements. The catalytic activities were evaluated for the vapor phase hydrogenation of nitrobenzene. The dispersion measured by CO-uptake values suggests that a decrease of dispersion is observed with increasing Ru loading on carbon support. These findings are well supported by the crystallite size measured from XRD measurements. XPS study reveals the formation of Ru0 after reduction at 573 K for 3 h. The catalysts exhibit high conversion/selectivity at 4.5 wt% Ru loading during hydrogenation reaction. The particle size measured from CO-chemisorption and TEM analysis are related to the TOF during the hydrogenation reaction. Ru/C catalysts are found to show higher conversion/selectivities during hydrogenation of nitrobenzene to aniline.

  13. Addition of titanium as a potential catalyst for a high-capacity hydrogen storage medium

    NARCIS (Netherlands)

    Zuliani, F.; Baerends, E.J.

    2008-01-01

    In recent years there has been increased interest in the characterization of titanium as a catalyst for high-capacity hydrogen storage materials. A first-principles study (Yildirim and Ciraci 2005 Phys. Rev. Lett. 94 175501) demonstrated that a single Ti atom coated on a single-walled nanotube

  14. Hydrogenation of fructose to 2,5-dimethyltetrahydrofuran using a sulfur poisoned Pt/C catalyst

    Science.gov (United States)

    In order to expand the number of biobased chemicals available, fructose has been hydrogenated to 2,5-dimethyltetrahydrofuran using a sulfided Pt/C catalyst. The reaction was carried out in a stirred reactor at 10.3 MPa H2 and 175°C which allowed a 10% fructose solution to be converted in about 2 h. ...

  15. Graphene/TiO2 hydrogel: a potential catalyst to hydrogen evolution ...

    Indian Academy of Sciences (India)

    Graphene/TiO2 hydrogel: a potential catalyst to hydrogen evolution reaction. VIRGIL CHRISTIAN CASTILLO1 and JULIET Q DALAGAN2,∗. 1Department of Chemistry, Ateneo de Manila University, Loyola Heights, Quezon City 1108, Philippines. 2Chemistry Department, Xavier University, Corrales Avenue, Cagayan de Oro ...

  16. Epoxidation of Alkenes with Aqueous Hydrogen Peroxide and Quaternary Ammonium Bicarbonate Catalysts

    DEFF Research Database (Denmark)

    Mielby, Jerrik Jørgen; Kegnæs, Søren

    2013-01-01

    A range of solid and liquid catalysts containing bicarbonate anions were synthesised and tested for the epoxidation of alkenes with aqueous hydrogen peroxide. The combination of bicarbonate anions and quaternary ammonium cations opens up for new catalytic systems that can help to overcome...

  17. Solid Catalyst with Ionic Liquid Layer (SCILL). A concept to improve the selectivity of selective hydrogenations

    Energy Technology Data Exchange (ETDEWEB)

    Jess, A.; Korth, W. [Bayreuth Univ. (Germany). Chair of Chemical Engineering

    2011-07-01

    Catalytic hydrogenations are important for refinery processes, petrochemical applications as well as for numerous processes of the fine chemicals industry. In some cases, hydrogenations consist of a sequence of consecutive reactions, and the desired product is the intermediate. An important goal is then a high yield and selectivity to the intermediate, if possible at a high conversion degree. The selectivity to an intermediate primarily depends on the chemical nature of the catalyst, but may also be influenced by diffusion processes. Ionic liquids (ILs) are low melting salts (< 100 C) and represent a promising solvent class. This paper focuses on the concept of a Solid Catalyst with Ionic Liquid Layer (SCILL), where the solid catalyst is coated with a thin IL layer to improve the selectivity. (orig.)

  18. Molecular molybdenum persulfide and related catalysts for generating hydrogen from water

    Science.gov (United States)

    Long, Jeffrey R.; Chang, Christopher J.; Karunadasa, Hemamala I.; Majda, Marcin

    2016-11-22

    New metal persulfido compositions of matter are described. In one embodiment the metal is molybdenum and the metal persulfido complex mimics the structure and function of the triangular active edge site fragments of MoS.sub.2, a material that is the current industry standard for petroleum hydro desulfurization, as well as a promising low-cost alternative to platinum for electrocatalytic hydrogen production. This molecular [(PY5W.sub.2)MoS.sub.2].sup.x+ containing catalyst is capable of generating hydrogen from acidic-buffered water or even seawater at very low overpotentials at a turnover frequency rate in excess of 500 moles H.sub.2 per mole catalyst per second, with a turnover number (over a 20 hour period) of at least 19,000,000 moles H.sub.2 per mole of catalyst.

  19. Molecular molybdenum persulfide and related catalysts for generating hydrogen from water

    Energy Technology Data Exchange (ETDEWEB)

    Long, Jeffrey R.; Chang, Christopher J.; Karunadasa, Hemamala I.; Majda, Marcin

    2016-04-19

    New metal persulfido compositions of matter are described. In one embodiment the metal is molybdenum and the metal persulfido complex mimics the structure and function of the triangular active edge site fragments of MoS.sub.2, a material that is the current industry standard for petroleum hydro desulfurization, as well as a promising low-cost alternative to platinum for electrocatalytic hydrogen production. This molecular [(PY5W.sub.2)MoS.sub.2].sup.x+ containing catalyst is capable of generating hydrogen from acidic-buffered water or even seawater at very low overpotentials at a turnover frequency rate in excess of 500 moles H.sub.2 per mole catalyst per second, with a turnover number (over a 20 hour period) of at least 19,000,000 moles H.sub.2 per mole of catalyst.

  20. Gas-phase hydrogenation/hydrogenolysis of phenol over supported nickel catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Shin, E.J.; Keane, M.A.

    2000-04-01

    The gas-phase hydrogenation/hydrogenolysis of alcoholic solutions of phenol between 423 and 573 K has been studied using a Y zeolite-supported nickel catalyst (2.2% w/w Ni) and Ni/SiO{sub 2} catalysts (1.5--20.3% w/w Ni). This is a viable means of treating concentrated phenol streams to generate recyclable raw material. Phenol hydrogenation proceeded in a stepwise fashion with cyclohexanone as a reactive intermediate while a combination of hydrogenolysis and hydrogenation yielded cyclohexane. Hydrogenolysis to benzene is favored by high nickel loadings and elevated temperatures. A catalytic hydrogen treatment of cyclohexanone and cyclohexanol helped to establish the overall reaction network/mechanism. The possible role of thermodynamic limitations is considered and structure sensitivity is addressed; reaction data are subjected to a pseudo-first-order kinetic treatment. Hydrogen temperature-programmed desorption (H{sub 2}-TPD) has revealed the existence of different forms of surface hydrogen. Selectivity is interpreted on the basis of the H{sub 2}-TPD profiles and the possible phenol/catalyst interactions. The zeolite sample only catalyzed (via the surface Bronsted acidity) anisole formation in the presence of methanol, but this was suppressed when hexanol was used; the zeolite then promoted hydrogenolysis. The zeolite, however, deactivated and this was not reversed by heating in hydrogen. The results of the hydrogen treatment of aqueous rather than alcoholic phenol solutions are presented, where a switch from methanol to water was accompanied by a move from highly selective hydrogenolysis to highly selective hydrogenation.

  1. Liquid-phase Hydrogenation of Phenol to Cyclohexanone over Supported Palladium Catalysts

    Directory of Open Access Journals (Sweden)

    Lihui Fan

    2016-10-01

    Full Text Available The ZSM-5, g-Al2O3, SiO2 and MgO supported Pd-catalysts were prepared for the phenol hydrogenation to cyclohexanone in liquid-phase. The natures of these catalysts were characterized by XRD, N2 adsorption-desorption analysis, H2-TPR, CO2-TPD and NH3-TPD. The catalytic performance of the supported Pd-catalyst for phenol hydrogenation to cyclohexanone is closely related to nature of the support and the size of Pd nanoparticles. The Pd/MgO catalyst which possesses higher basicity shows higher cyclohexanone selectivity, but lower phenol conversion owing to the lower specific surface area. The Pd/SiO2 catalyst prepared by precipitation gives higher cyclohexanone selectivity and phenol conversion, due to the moderate amount of Lewis acidic sites, and the smaller size and higher dispersion of Pd nanoparticles on the surface. Under the reaction temperature of 135 oC and H2 pressure of 1 MPa, after reacting for 3.5 h, the phenol conversion of 71.62% and the cyclohexanone selectivity of 90.77% can be obtained over 0.5 wt% Pd/SiO2 catalyst. Copyright © 2016 BCREC GROUP. All rights reserved Received: 7th March 2016; Revised: 13rd May 2016; Accepted: 7th June 2016 How to Cite: Fan, L., Zhang, L., Shen, Y., Liu, D., Wahab, N., Hasan, M.M. (2016. Liquid-phase Hydrogenation of Phenol to Cyclohexanone over Supported Palladium Catalysts. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (3: 354-362 (doi: 10.9767/bcrec.11.3.575.354-362 Permalink/DOI: http://doi.org/10.9767/bcrec.11.3.575.354-362

  2. BINIVOX catalyst for hydrogen production from ethanol by low ...

    Indian Academy of Sciences (India)

    Nickel doped bismuth vanadate [Bi₄ (V₀. ₉₀Ni₀.₁₀) ₂ O₁₁ ₋ δ;BINIVOX] calcined at 800 ◦C (BINIVOX-800) catalyst is prepared by a solution combustion method. The catalytic activity study is carriedin the temperature range of 250–400 ◦C, and with the molar feed ratios of water: ethanol at 23:1 and 2.5:1. The study ...

  3. Production of hydrogen for fuel cells by catalytic partial oxidation of ethanol over structured Ru catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Liguras, D.K.; Goundani, K.; Verykios, X.E. [University of Patras (Greece). Dept. of Chemical Engineering

    2004-03-01

    A series of Ru catalysts supported on cordierite monoliths, ceramic foams and {gamma}-Al{sub 2}O{sub 3} pellets were prepared and tested for the production of hydrogen by catalytic partial oxidation of ethanol. The catalyst supported on a cordierite monolith exhibited excellent catalytic performance for a wide variety of process conditions and excellent long-term stability with low coke formation. The effect of the steam to ethanol molar ratio on conversion and selectivities was relatively small. A more pronounced effect was observed for the oxygen to ethanol ratio. Overall, catalysts on all three supports were able to completely convert ethanol with high selectivities towards the desired products. The Ru supported on a ceramic foam catalyst provided comparatively better performance, probably due to the smaller pore sizes and higher tortuosity of this support. (author)

  4. Reversibility of hydrogen chemisorption on a ceria-supported rhodium catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Bernal, S.; Calvino, J.J.; Cifredo, G.A.; Izquierdo, J.M. Rodriguez (Univ. de Cadiz, Perto Real (Spain)); Perrichon, V.; Laachir, A. (Inst. de Recherches sur la Catalyse (France))

    1992-09-01

    Cerium dioxide is an important component of the so-called three-way catalysts. This work reports on some new aspects of the chemistry of hydrogen-ceria systems. It is shown that, at room temperature, in the presence of highly dispersed rhodium, ceria chemisorbs large amounts of hydrogen. As deduced from magnetic measurements carried out in situ, this spillover process leads to the reduction of ceria to an extent of 21% of the total amount of cerium ions present in the sample, which is roughly equivalent to the complete surface reduction of the oxide. It is found that over a highly hydroxylated sample the reduction of ceria induced by the spillover process is partly reversible even at 295 K. If the sample is pumped off at 773 K, the initial oxidation state of ceria is almost completely recovered. Both the rate and extent of hydrogen chemisorption on ceria were found to be sensitive to the specific pretreatment applied to the catalyst. Over bare ceria, hydrogen chemisorption at 298 K was negligible, temperatures as high as 473 K being necessary to activate the process. In contrast to the rhodium-containing catalyst, over pure ceria the desorption of hydrogen leads to a much larger extent to water formation, thus revealing a deeper irreversible reduction of the oxide.

  5. Molecular cobalt pentapyridine catalysts for generating hydrogen from water

    Science.gov (United States)

    Long, Jeffrey R; Chang, Christopher J; Sun, Yujie

    2013-11-05

    A composition of matter suitable for the generation of hydrogen from water is described, the positively charged cation of the composition including the moiety of the general formula. [(PY5Me.sub.2)CoL].sup.2+, where L can be H.sub.2O, OH.sup.-, a halide, alcohol, ether, amine, and the like. In embodiments of the invention, water, such as tap water or sea water can be subject to low electric potentials, with the result being, among other things, the generation of hydrogen.

  6. Dodecahedral W@WC Composite as Efficient Catalyst for Hydrogen Evolution and Nitrobenzene Reduction Reactions.

    Science.gov (United States)

    Chen, Zhao-Yang; Duan, Long-Fa; Sheng, Tian; Lin, Xiao; Chen, Ya-Feng; Chu, You-Qun; Sun, Shi-Gang; Lin, Wen-Feng

    2017-06-21

    Core-shell composites with strong phase-phase contact could provide an incentive for catalytic activity. A simple, yet efficient, H2O-mediated method has been developed to synthesize a mesoscopic core-shell W@WC architecture with a dodecahedral microstructure, via a one-pot reaction. The H2O plays an important role in the resistance of carbon diffusion, resulting in the formation of the W core and W-terminated WC shell. Density functional theory (DFT) calculations reveal that adding W as core reduced the oxygen adsorption energy and provided the W-terminated WC surface. The W@WC exhibits significant electrocatalytic activities toward hydrogen evolution and nitrobenzene electroreduction reactions, which are comparable to those found for commercial Pt/C, and substantially higher than those found for meso- and nano-WC materials. The experimental results were explained by DFT calculations based on the energy profiles in the hydrogen evolution reactions over WC, W@WC, and Pt model surfaces. The W@WC also shows a high thermal stability and thus may serve as a promising more economical alternative to Pt catalysts in these important energy conversion and environmental protection applications. The current approach can also be extended or adapted to various metals and carbides, allowing for the design and fabrication of a wide range of catalytic and other multifunctional composites.

  7. Bio-inspired co-catalysts bonded to a silicon photocathode for solar hydrogen evolution

    DEFF Research Database (Denmark)

    Hou, Yidong; Abrams, Billie; Vesborg, Peter Christian Kjærgaard

    2011-01-01

    part of the spectrum is utilized for hydrogen evolution while the blue part is reserved for the more difficult oxygen evolution. The samples have been illuminated with a simulated red part of the solar spectrum i.e. long wavelength (" > 620 nm) part of simulated AM 1.5G radiation. The current densities...... deposited on various supports. It will be demonstrated how this overpotential can be eliminated by depositing the same type of hydrogen evolution catalyst on p-type Si which can harvest the red part of the solar spectrum. Such a system could constitute the cathode part of a tandem dream device where the red...... at the reversible potential match the requirement of a photoelectrochemical hydrogen production system with a solar-to-hydrogen efficiency in excess of 10%. The experimental observations are supported by DFT calculations of the Mo3S4 cluster adsorbed on the hydrogen-terminated silicon surface providing insights...

  8. Palladium - potassium humate coated by Polymetallic catalysts for the process of hydrogenation of nitrocompounds

    Directory of Open Access Journals (Sweden)

    E. Yermoldina

    2013-09-01

    Full Text Available Results of studies of humic substances in the quality of natural polymeric modifier for the coated palladium catalysts are presented in the paper. Synthesis of new catalysts based on palladium - potassium humate fixed on various inorganic carriers and their catalytic properties have been studied. The catalysts of 0,8% Pd - Potassium’s Humat(1%/B-94 and 0,8% Pd /Shungite 1% КОН are optimal.

  9. Production of Renewable Hydrogen from Glycerol Steam Reforming over Bimetallic Ni-(Cu,Co,Cr Catalysts Supported on SBA-15 Silica

    Directory of Open Access Journals (Sweden)

    Alicia Carrero

    2017-02-01

    Full Text Available Glycerol steam reforming (GSR is a promising alternative to obtain renewable hydrogen and help the economics of the biodiesel industry. Nickel-based catalysts are typically used in reforming reactions. However, the choice of the catalyst greatly influences the process, so the development of bimetallic catalysts is a research topic of relevant interest. In this work, the effect of adding Cu, Co, and Cr to the formulation of Ni/SBA-15 catalysts for hydrogen production by GSR has been studied, looking for an enhancement of its catalytic performance. Bimetallic Ni-M/SBA-15 (M: Co, Cu, Cr samples were prepared by incipient wetness co-impregnation to reach 15 wt % of Ni and 4 wt % of the second metal. Catalysts were characterized by inductively coupled plasma atomic emission spectroscopy (ICP-AES, N2-physisorption, X-ray powder diffraction (XRD, hydrogen temperature programmed reduction (H2-TPR, transmission electron microscopy (TEM, scanning electron microscopy (SEM, and thermogravimetric analyses (TGA, and tested in GSR at 600 °C and atmospheric pressure. The addition of Cu, Co, and Cr to the Ni/SBA-15 catalyst helped to form smaller crystallites of the Ni phase, this effect being more pronounced in the case of the Ni-Cr/SBA-15 sample. This catalyst also showed a reduction profile shifted towards higher temperatures, indicating stronger metal-support interaction. As a consequence, the Ni-Cr/SBA-15 catalyst exhibited the best performance in GSR in terms of glycerol conversion and hydrogen production. Additionally, Ni-Cr/SBA-15 achieved a drastic reduction in coke formation compared to the Ni/SBA-15 material.

  10. CO2 hydrogenation over Pd-modified methanol synthesis catalysts

    NARCIS (Netherlands)

    Melián-Cabrera, I.; López Granados, M.; Terreros, P.; Fierro, J.L.G.

    1998-01-01

    The effect of palladium incorporation on the performance of Cu-ZnO(Al2O3) during the hydrogenation of carbon dioxide has been assessed. Temperature-programmed reduction profiles and X-ray photoelectron spectra of copper revealed that Pd enhances copper oxide reduction. Carbon dioxide conversion and

  11. Natural manganese deposits as catalyst for decomposing hydrogen peroxide

    NARCIS (Netherlands)

    Knol, A.H.; Lekkerkerker-Teunissen, K.; Van Dijk, J.C.

    2015-01-01

    Drinking water companies (are intending to) implement advanced oxidation processes (AOP) in their treatment schemes to increase the barrier against organic micropollutants (OMPs). It is necessary to decompose the excessive hydrogen peroxide after applying AOP to avoid negative effects in the

  12. In tandem or alone: a remarkably selective transfer hydrogenation of alkenes catalyzed by ruthenium olefin metathesis catalysts.

    Science.gov (United States)

    Zieliński, Grzegorz Krzysztof; Samojłowicz, Cezary; Wdowik, Tomasz; Grela, Karol

    2015-03-07

    A system for transfer hydrogenation of alkenes, composed of a ruthenium metathesis catalyst and HCOOH, is presented. This operationally simple system can be formed directly after a metathesis reaction to effect hydrogenation of the metathesis product in a single-pot. These hydrogenation conditions are applicable to a wide range of alkenes and offer remarkable selectivity.

  13. Magnetic Fe@g-C3N4: A Photoactive Catalyst for the Hydrogenation of Alkenes and Alkynes

    Science.gov (United States)

    A photoactive catalyst, Fe@g-C3N4, has been developed for the hydrogenation of alkenes and alkynes using hydrazine hydrate as a source of hydrogen. The magnetically separable Fe@g-C3N4 eliminates the use of high pressure hydrogenation and the reaction can be accomplished using vi...

  14. The effects of yttrium on the hydrogenation performance and surface properties of a ruthenium-supported catalyst

    Directory of Open Access Journals (Sweden)

    LAITAO LUO

    2005-12-01

    Full Text Available The effects of yttrium on the hydrogenation performance and surface properties of a Ru/sepiolite catalyst were studied. With CO2 methanation and CS2 poisoning as the testing reactons, TPR, TPD, XRD and CO chemisorption as the characterizations, the results showed that the presence of yttrium can increase the hydrogenation activity and anti-poisoning capacity of the Ru/sepiolite catalyst, which is due to a change of surface properties of the Ru/sepiolite. In the process of the catalytic reaction, the adjusting behavior of yttrium for the Ru/sepiolite catalyst aids in increasing the catalytic activity and anti-poisoning capacity of the catalyst.

  15. Oxygen tolerance of an in silico-designed bioinspired hydrogen-evolving catalyst in water.

    Science.gov (United States)

    Sit, Patrick H-L; Car, Roberto; Cohen, Morrel H; Selloni, Annabella

    2013-02-05

    Certain bacterial enzymes, the diiron hydrogenases, have turnover numbers for hydrogen production from water as large as 10(4)/s. Their much smaller common active site, composed of earth-abundant materials, has a structure that is an attractive starting point for the design of a practical catalyst for electrocatalytic or solar photocatalytic hydrogen production from water. In earlier work, our group has reported the computational design of [FeFe](P)/FeS(2), a hydrogenase-inspired catalyst/electrode complex, which is efficient and stable throughout the production cycle. However, the diiron hydrogenases are highly sensitive to ambient oxygen by a mechanism not yet understood in detail. An issue critical for practical use of [FeFe](P)/FeS(2) is whether this catalyst/electrode complex is tolerant to the ambient oxygen. We report demonstration by ab initio simulations that the complex is indeed tolerant to dissolved oxygen over timescales long enough for practical application, reducing it efficiently. This promising hydrogen-producing catalyst, composed of earth-abundant materials and with a diffusion-limited rate in acidified water, is efficient as well as oxygen tolerant.

  16. Hydrogen generation from decomposition of hydrous hydrazine over Ni-Ir/CeO2 catalyst

    Directory of Open Access Journals (Sweden)

    Hongbin Dai

    2017-02-01

    Full Text Available The synthesis of highly active and selective catalysts is the central issue in the development of hydrous hydrazine (N2H4·H2O as a viable hydrogen carrier. Herein, we report the synthesis of bimetallic Ni-Ir nanocatalyts supported on CeO2 using a one-pot coprecipitation method. A combination of XRD, HRTEM and XPS analyses indicate that the Ni-Ir/CeO2 catalyst is composed of tiny Ni-Ir alloy nanoparticles with an average size of around 4 nm and crystalline CeO2 matrix. The Ni-Ir/CeO2 catalyst exhibits high catalytic activity and excellent selectivity towards hydrogen generation from N2H4·H2O at mild temperatures. Furthermore, in contrast to previously reported Ni-Pt catalysts, the Ni-Ir/CeO2 catalyst shows an alleviated requirement on alkali promoter to achieve its optimal catalytic performance.

  17. Durable PROX catalyst based on gold nanoparticles and hydrophobic silica

    KAUST Repository

    Laveille, Paco

    2016-01-20

    3 nm gold nanoparticles (Au NP) obtained by direct chemical reduction of AuPPh3Cl in the presence of methyl-terminated silica exhibit superior durability for low temperature CO oxidation in the presence of hydrogen (PROX). The activity of hydrophobic Au/SiO2-R972 indeed appears much more stable with time-on-stream than those of the OH-terminated, hydrophilic Au/TiO2 and Au/Al2O3 catalysts, with similar Au NP size. This enhanced stability is attributed to the peculiar catalyst surface of Au/SiO2-R972. Not only may the support hydrophobicity concentrate and facilitate reactant adsorption and product desorption over Au NP, but methyl-terminated SiO2-R972 likely also inhibits carbonatation of the Au/support interface. Hence, at a temperature at which H2/H2O “cleaning” of the carbonate-contaminated Au/Al2O3 and Au/TiO2 surface is inefficient (< 100°C), passivated Au/SiO2-R972 displays much more stable PROX activity. Besides, the virtual absence of surface hydroxyl groups, which provide sites for water formation in H2/O2 atmospheres, can also account for the improved PROX selectivity (>85%) observed over Au/SiO2-R972. This new example, of CO oxidation activity of gold nanoparticles dispersed over a hydrophobic, “inert” support, clearly emphasizes the role of hydrogen as a promoter for the gold-catalyzed oxidation of CO at low temperature. Unlike support-mediated oxygen activation, hydrogen-only mediated oxygen activation takes full advantage of the hydrophobic surface, which is much more resistant against CO2 and thus remains free of poisonous carbonate species, as compared with hydroxyl-terminated catalysts. Hence, although the absence of surface hydroxyl groups prevents the hydrophobic Au/SiO2-R972 catalyst to reach the state-of-the-art activities initially displayed by Au/TiO2 and Au/Al2O3, it brings long-term stability with time-on-stream and superior selectivity, which opens up promising perspectives in the development of viable PROX catalysts based on gold.

  18. Continuous hydrogenation of ethyl levulinate to γ-valerolactone and 2-methyl tetrahydrofuran over alumina doped Cu/SiO2 catalyst: the potential of commercialization

    Science.gov (United States)

    Zheng, Junlin; Zhu, Junhua; Xu, Xuan; Wang, Wanmin; Li, Jiwen; Zhao, Yan; Tang, Kangjian; Song, Qi; Qi, Xiaolan; Kong, Dejin; Tang, Yi

    2016-01-01

    Hydrogenation of levulinic acid (LA) and its esters to produce γ-valerolactone (GVL) and 2-methyl tetrahydrofuran (2-MTHF) is a key step for the utilization of cellulose derived LA. Aiming to develop a commercially feasible base metal catalyst for the production of GVL from LA, with satisfactory activity, selectivity, and stability, Al2O3 doped Cu/SiO2 and Cu/SiO2 catalysts were fabricated by co-precipitation routes in parallel. The diverse physio-chemical properties of these two catalysts were characterized by XRD, TEM, dissociative N2O chemisorptions, and Py-IR methods. The catalytic properties of these two catalysts were systematically assessed in the continuous hydrogenation of ethyl levulinate (EL) in a fixed-bed reactor. The effect of acidic property of the SiO2 substrate on the catalytic properties was investigated. To justify the potential of its commercialization, significant attention was paid on the initial activity, proper operation window, by-products control, selectivity, and stability of the catalyst. The effect of reaction conditions, such as temperature and pressure, on the performance of the catalyst was also thoroughly studied. The development of alumina doped Cu/SiO2 catalyst strengthened the value-chain from cellulose to industrially important chemicals via LA and GVL. PMID:27377401

  19. Metallic Ni3 P/Ni Co-Catalyst To Enhance Photocatalytic Hydrogen Evolution.

    Science.gov (United States)

    Zhao, Jun Jie; Liu, Peng Fei; Wang, Yu Lei; Li, Yu Hang; Zu, Meng Yang; Wang, Chong Wu; Wang, Xue Lu; Fang, Li Jun; Zeng, Hui Dan; Yang, Hua Gui

    2017-11-27

    Metallic Ni3 P/Ni can be used as a co-catalyst to replace noble metal Pt for efficient photocatalytic hydrogen evolution, due to its excellent trapping-electron ability. The applications of metallic Ni3 P/Ni co-catalyst on CdS, Zn0.5 Cd0.5 S, TiO2 (Degussa P25) and g-C3 N4 are further confirmed, indicating its versatile applicability nature like Pt. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Kinetic study of the selective hydrogenation of styrene over a Pd egg-shell composite catalyst

    OpenAIRE

    Betti,Carolina; Badano,Juan; Lederhos,Cecilia; Maccarrone, María; Carrara, Nicolás; Coloma, Fernando; Quiroga, Mónica; Vera, Carlos

    2016-01-01

    This is a study on the kinetics of the liquid-phase hydrogenation of styrene to ethylbenzene over a catalyst of palladium supported on an inorganic–organic composite. This support has a better mechanical resistance than other commercial supports, e.g. alumina, and yields catalysts with egg-shell structure and a very thin active Pd layer. Catalytic tests were carried out in a batch reactor by varying temperature, total pressure and styrene initial concentration between 353–393 K, 10–30 bar, an...

  1. New Catalyst for HER and CO2 Hydrogenation for Solar Fuel Production

    DEFF Research Database (Denmark)

    Chorkendorff, Ib

    2013-01-01

    group [7]. Hereby it is possible to achieve photoelectrochemical H2 production at +0.33 V vs. RHE using a porous, amorphous MoSx catalyst. To stabilize Si during catalyst deposition and the subsequent hydrogen evolution reaction (HER), a corrosion protective layer is shown to be indispensable. At 200m......V positive of RHE the cell produce an incident photon to current efficiency (IPCE) of 50%. This work represents a substantial reduction in H2 evolution overpotential for non-Pt Si-photocathode operated in acidic solution. Further improvement in corrosion protection using several 100 nm of TiO2 [8...

  2. Hydrogenation of o-cresol on platinum catalyst: Catalytic experiments and first-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yaping [Department of Physics and Engineering Physics, The University of Tulsa, Tulsa, OK 74104 (United States); Liu, Zhimin [School of Chemical, Biological and Materials Engineering, University of Oklahoma, Norman, OK 73019 (United States); Xue, Wenhua [Department of Physics and Engineering Physics, The University of Tulsa, Tulsa, OK 74104 (United States); Crossley, Steven P.; Jentoft, Friederike C. [School of Chemical, Biological and Materials Engineering, University of Oklahoma, Norman, OK 73019 (United States); Wang, Sanwu, E-mail: sanwu-wang@utulsa.edu [Department of Physics and Engineering Physics, The University of Tulsa, Tulsa, OK 74104 (United States)

    2017-01-30

    Highlights: • Hydrogenation of o-cresol over Pt results in formation of two products. • Dissociation of hydrogen from the −OH group involves a low activation energy. • Following hydrogenation of the aromatic ring forms 2-methyl-cyclohexanone. • Further hydrogenation produces the final product, 2-methyl-cyclohexanol. - Abstract: Catalytic experiments were performed for the hydrogenation of o-cresol in n-dodecane over a platinum catalyst. Batch reactions analyzed with an in-situ ATR IR probe suggest that the hydrogenation results in the formation of the final product, 2-methyl-cyclohexanol, with 2-methyl-cyclohexanone as the intermediate product. Ab initio density-functional theory was employed to investigate the atomic-scale mechanism of o-cresol hydrogenation on the Pt(111) surface. The formation of 2-methyl-cyclohexanone was found to involve two steps. The first step is a hydrogen abstraction, that is, the H atom in the hydroxyl group migrates to the Pt surface. The second step is hydrogenation, that is, the pre-existing H atoms on Pt react with the carbon atoms in the aromatic ring. On the other hand, 2-methyl-cyclohexanonol may be produced through two paths, with activation energies slightly greater than that for the formation of 2-methyl-cyclohexanone. One path involves direct hydrogenation of the aromatic ring. Another path involves three steps, with the partial hydrogenation of the ring as the first step, hydrogen abstraction of the −OH group as the second, and hydrogenation of remaining C atoms and the O atom the last.

  3. Tungsten effect over co-hydrotalcite catalysts to produce hydrogen from bio-ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Contreras, J.L.; Ortiz, M.A.; Luna, R.; Nuno, L. [Univ. Autonoma Metropolitana-Azcapozalco, Mexico City (Mexico). Dept. de Energia; Fuentes, G.A. [Univ. Autonoma Metropolitana-Iztapalapa, Mexico City (Mexico). Dept. de IPH; Salmones, J.; Zeifert, B. [Inst. Politecnico Nacional, Mexico City (Mexico); Vazquez, A. [Inst. Mexicano del Petroleo, Mexico City (Mexico)

    2010-07-15

    The use of bioethanol has been considered for generating hydrogen via catalytic reforming. The reaction of ethanol with stream is strongly endothermic and produces hydrogen (H{sub 2}) and carbon dioxide (CO{sub 2}). However, undesirable products such as carbon monoxide (CO) and methane (CH{sub 4}) may also form during the reaction. This paper reported on the newly found stabilization effect of tungsten over the Co-hydrotalcite catalysts to produce H{sub 2} from ethanol in steam reforming. The catalysts were characterized by nitrogen (N{sub 2}) physisorption (BET area), X-ray diffraction, Infrared, Raman and UV-vis spectroscopies. Catalytic evaluations were determined using a fixed bed reactor with a water/ethanol mol ratio of 4 at 450 degrees C. The tungsten concentration studied was from 0.5 to 3 wt percent. The intensity of crystalline reflections of the Co-hydrotalcite catalysts decreased as tungsten concentration increased. Infrared spectroscopy was used to determine the superficial chemical groups, notably -OH, H{sub 2}O, Al-OH, Mg-OH, W-O-W and CO{sub 3}{sup 2.} The highest H{sub 2} production and the best catalytic stability was found in catalysts with low tungsten. The smallest pore volume of this catalyst could be related with long residence times of ethanol in the pores. Tungsten promoted the conversion for the Co-hydrotalcite catalysts. The reaction products were H{sub 2}, CO{sub 2}, CH{sub 3}CHO, CH{sub 4} and C{sub 2}H{sub 4} and the catalysts did not produce CO. 33 refs., 2 tabs., 10 figs.

  4. Hydrogenation of carboxylic acids with a homogeneous cobalt catalyst.

    Science.gov (United States)

    Korstanje, Ties J; van der Vlugt, Jarl Ivar; Elsevier, Cornelis J; de Bruin, Bas

    2015-10-16

    The reduction of esters and carboxylic acids to alcohols is a highly relevant conversion for the pharmaceutical and fine-chemical industries and for biomass conversion. It is commonly performed using stoichiometric reagents, and the catalytic hydrogenation of the acids previously required precious metals. Here we report the homogeneously catalyzed hydrogenation of carboxylic acids to alcohols using earth-abundant cobalt. This system, which pairs Co(BF4)2·6H2O with a tridentate phosphine ligand, can reduce a wide range of esters and carboxylic acids under relatively mild conditions (100°C, 80 bar H2) and reaches turnover numbers of up to 8000. Copyright © 2015, American Association for the Advancement of Science.

  5. Carbon monoxide hydrogenation on Co--Rh/Nb{sub 2}O{sub 5} catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Frydman, A.; Castner, D.G.; Campbell, C.T.; Schmal, M.

    1999-11-15

    Carbon monoxide hydrogenation activities and product distributions were investigated here for the first time on a series of seven Co-Rh/Nb{sub 2}O{sub 5} catalysts: two monometallics Co and Rh supported on Nb{sub 2}O{sub 5} and five bimetallics CO-RH supported on NB{sub 2}O{sub 5} with similar Co ({approximately}1.9 wt%) and variable Rh loadings (0.3--2.3 wt%). Catalytic performances at atmospheric pressure and 493 K were evaluated after low temperature reduction (LTR, 533--573 K) and after high temperature reduction (HTR, 773 K). Temperature-programmed reduction characterization revealed that the reduction temperature of the dominant Co phase on calcined catalysts, Co{sub 3}O{sub 4}, strongly decreased as the Rh/Co bulk atomic ratio increased, while the reduction temperature of the RH{sub 2}O{sub 3} phase (363 to 419 K) was not strongly influenced by the presence of Co{sub 3}O{sub 4}. It was observed that the activity decay effect caused by metal-support interaction was remarkably inhibited on the bimetallics with respect to the monometallics by comparing reaction rate after LTR and after HTR. The addition of Rh to the Co monometallic catalyst significantly altered the product distribution. An unusual promotion of the selectivity to long chain hydrocarbons were observed. This promotion was more intense after HTR on the bimetallic catalysts, reaching {approximately}56% in the diesel fraction on the bimetallic catalyst with higher Rh concentration. Alcohol selectivity was enhanced up to 3.5 and 5.4% for ethanol and propanol, respectively, on the bimetallic catalyst with lower Rh concentration. The total CO hydrogenation reaction rate and the selectivity for methane were approximately constant as the Rh concentration on the bimetallics increased, suggesting that the metal surface area did not vary considerably on these catalysts. This agrees with hydrogen adsorption measurements on the bimetallic catalysts and with the XPS surface structural characterization of the

  6. Hydrogenation of Levulinic Acid to gamma-Valerolactone in Water Using Millimeter Sized Supported Ru Catalysts in a Packed Bed Reactor

    NARCIS (Netherlands)

    Piskun, A. S.; de Haan, J. E.; Wilbers, E.; de Bovenkamp, H. H. van; Tang, Z.; Heeres, Hero

    gamma-Valerolactone (GVL) has been identified as a sustainable platform chemical for the production of carbon-based chemicals. We here report an experimental study on the catalytic hydrogenation of levulinic acid (LA) in water to GVL in a packed bed reactor using supported Ru catalysts (carbon,

  7. Direct Mannich-Type Reactions Promoted by Frustrated Lewis Acid/Brønsted Base Catalysts.

    Science.gov (United States)

    Chan, Jessica Z; Yao, Wenzhi; Hastings, Brian T; Lok, Charles K; Wasa, Masayuki

    2016-10-24

    Direct Mannich-type reactions that afford both α- and β-amino esters by the reaction of a broad range of carbonyl compounds and aldimines are disclosed. The transformation is promoted by a sterically frustrated Lewis acid/Brønsted base pair, which is proposed to operate cooperatively: Within the catalyst complex, an enolate is generated that then reacts with a hydrogen-bond-activated imine. Noncovalent interactions between reactants and the catalyst provide selectivity and new opportunities for future catalyst design. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Synthesis of Hydrocarbons from H2-Deficient Syngas in Fischer-Tropsch Synthesis over Co-Based Catalyst Coupled with Fe-Based Catalyst as Water-Gas Shift Reaction

    Directory of Open Access Journals (Sweden)

    Ting Ma

    2015-01-01

    Full Text Available The effects of metal species in an Fe-based catalyst on structural properties were investigated through the synthesis of Fe-based catalysts containing various metal species such, as Mn, Zr, and Ce. The addition of the metal species to the Fe-based catalyst resulted in high dispersions of the Fe species and high surface areas due to the formation of mesoporous voids about 2–4 nm surrounded by the catalyst particles. The metal-added Fe-based catalysts were employed together with Co-loaded beta zeolite for the synthesis of hydrocarbons from syngas with a lower H2/CO ratio of 1 than the stoichiometric H2/CO ratio of 2 for the Fischer-Tropsch synthesis (FTS. Among the catalysts, the Mn-added Fe-based catalyst exhibited a high activity for the water-gas shift (WGS reaction with a comparative durability, leading to the enhancement of the CO hydrogenation in the FTS in comparison with Co-loaded beta zeolite alone. Furthermore, the loading of Pd on the Mn-added Fe-based catalyst enhanced the catalytic durability due to the hydrogenation of carbonaceous species by the hydrogen activated over Pd.

  9. Fe(III)-functionalized carbon dots—Highly efficient photoluminescence redox catalyst for hydrogenations of olefins and decomposition of hydrogen peroxide

    KAUST Repository

    Bourlinos, Athanasios B.

    2017-03-21

    We present the first bottom-up approach to synthesize Fe(III)-functionalized carbon dots (CDs) from molecular precursors without the need of conventional thermal or microwave treatment and additional reagents. Specifically, sonication of xylene in the presence of anhydrous FeCl3 results in oxidative coupling of the aromatic substrate towards Fe(III)-functionalized CDs. The as-prepared CDs are spherical in shape with a size of 3–8 nm, highly dispersible in organic solvents and display wavelength-dependent photoluminescence (PL). The iron ions attached to the surface endow the CDs with superior catalytic activity for olefin hydrogenation with excellent conversion and selectivity (up to 100%). The Fe(III)-CDs are more effective in the hydrogenation of a series of electron donating or withdrawing olefin substrates compared to conventional homogeneous or heterogeneous Fe(III)-based catalysts. The as-prepared heterogeneous nanocatalyst can be used repeatedly without any loss of catalytic activity. Importantly, the stability of the new catalysts can be easily monitored by PL intensity or quantum yield measurements, which certainly opens the doors for real time monitoring in a range of applications. Additionally, to the best of our knowledge, for the first time, the oxidative property of Fe-CDs was also explored in decomposition of hydrogen peroxide in water with the first order rate constant of 0.7 × 10−2 min−1, proving the versatile catalytic properties of such hybrid systems.

  10. Sulfidic vapor phase catalysts, especially tungsten sulfide, in industrial coal hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Pier, M.

    1943-01-01

    The historical development of high-pressure processes of the I. G. Farbenindustrie, from ammonia through methanol and gasoline, and the special case of gasoline production with a fixed-bed catalyst (tungsten sulfide) were discussed. The preparation, properties, and uses of this versatile catalyst were discussed, but it was emphasized that with the sotrmy development of the process, a condition which still existed at the time of this report, and with a great number of practical problems to solve, no extensive study of basic facts had ben possible. This tungsten sulfide catalyst was an especially active vapor-phase catalyst which operated at lower temperatures than the molybdenum catalysts formerly used. It also permitted higher thruputs, even with the oils from bituminous coal that were difficult to split. For certain uses, such as the improvement of the antiknock properties or the saving in tungsten, it was strongly diluted. Studies on using up sulfur in the tungsten sulfide catalyst were in progress at this time and showed there was practically no reduction of it under the conditions of hydrogenation under pressure as long as the raw material contained sulfur.

  11. Stable hydrogen production from ethanol through steam reforming reaction over nickel-containing smectite-derived catalyst.

    Science.gov (United States)

    Yoshida, Hiroshi; Yamaoka, Ryohei; Arai, Masahiko

    2014-12-25

    Hydrogen production through steam reforming of ethanol was investigated with conventional supported nickel catalysts and a Ni-containing smectite-derived catalyst. The former is initially active, but significant catalyst deactivation occurs during the reaction due to carbon deposition. Side reactions of the decomposition of CO and CH4 are the main reason for the catalyst deactivation, and these reactions can relatively be suppressed by the use of the Ni-containing smectite. The Ni-containing smectite-derived catalyst contains, after H2 reduction, stable and active Ni nanocrystallites, and as a result, it shows a stable and high catalytic performance for the steam reforming of ethanol, producing H2.

  12. Catalytic Transformation of Ethylbenzene over Y-Zeolite-based Catalysts

    KAUST Repository

    Al-Khattaf, Sulaiman

    2008-11-19

    Catalytic transformation of ethylbenzene (EB) has been investigated over ultrastable Y (USY)-zeolite-based catalysts in a novel riser simulator at different operating conditions. The effect of reaction conditions on EB conversion is reported. The USY catalyst (FCC-Y) was modified by steaming to form a significantly lower acidity catalyst (FCC-SY). The current study shows that the FCC-SY catalyst favors EB disproportionation more than cracking. A comparison has been made between the results of EB conversion over the lowly acidic catalyst (FCC-SY) and the highly acidic catalyst (FCC-Y) under identical conditions. It was observed that increase in catalyst acidity favored cracking of EB at the expense of disproportionation. Kinetic parameters for EB disappearance during disproportionation reaction over the FCC-SY catalyst were calculated using the catalyst activity decay function based on time on stream (TOS). © 2008 American Chemical Society.

  13. MoB/g-C3 N4 Interface Materials as a Schottky Catalyst to Boost Hydrogen Evolution.

    Science.gov (United States)

    Zhuang, Zechao; Li, Yong; Li, Zilan; Lv, Fan; Lang, Zhiquan; Zhao, Kangning; Zhou, Liang; Moskaleva, Lyudmila; Guo, Shaojun; Mai, Liqiang

    2018-01-08

    Proton adsorption on metallic catalysts is a prerequisite for efficient hydrogen evolution reaction (HER). However, tuning proton adsorption without perturbing metallicity remains a challenge. A Schottky catalyst based on metal-semiconductor junction principles is presented. With metallic MoB, the introduction of n-type semiconductive g-C3 N4 induces a vigorous charge transfer across the MoB/g-C3 N4 Schottky junction, and increases the local electron density in MoB surface, confirmed by multiple spectroscopic techniques. This Schottky catalyst exhibits a superior HER activity with a low Tafel slope of 46 mV dec-1 and a high exchange current density of 17 μA cm-2 , which is far better than that of pristine MoB. First-principle calculations reveal that the Schottky contact dramatically lowers the kinetic barriers of both proton adsorption and reduction coordinates, therefore benefiting surface hydrogen generation. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Pt/SnO2-based CO-oxidation catalysts for long-life closed-cycle CO2 lasers

    Science.gov (United States)

    Schryer, David R.; Upchurch, Billy T.; Hess, Robert V.; Wood, George M.; Sidney, Barry D.; Miller, Irvin M.; Brown, Kenneth G.; Vannorman, John D.; Schryer, Jacqueline; Brown, David R.

    1990-01-01

    Noble-metal/tin-oxide based catalysts such as Pt/SnO2 have been shown to be good catalysts for the efficient oxidation of CO at or near room temperature. These catalysts require a reductive pretreatment and traces of hydrogen or water to exhibit their full activity. Addition of Palladium enhances the activity of these catalysts with about 15 to 20 percent Pt, 4 percent Pd, and the balance SnO2 being an optimum composition. Unfortunately, these catalysts presently exhibit significant decay due in part to CO2 retention, probably as a bicarbonate. Research on minimizing the decay in activity of these catalysts is currently in progress. A proposed mechanism of CO oxidation on Pt/SnO2-based catalysts has been developed and is discussed.

  15. Hydrogen production by sequential cracking of biomass-derived pyrolysis oil over noble metal catalysts supported on ceria-zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Iojoiu, Eduard Emil; Domine, Marcelo Eduardo; Davidian, Thomas; Guilhaume, Nolven; Mirodatos, Claude [Institut de Recherches sur la Catalyse et l' Environnement de Lyon IRCELYON, UMR5256 CNRS Universite Lyon 1, 2 avenue Albert Einstein, F-69626 Villeurbanne cedex (France)

    2007-04-30

    Conversion of crude pyrolysis bio-oil for H{sub 2} production is investigated using a sequential process which alternates (1) cracking reaction steps, during which the bio-oil is converted to syngas and carbon stored on the catalyst and (2) regeneration steps allowing to combust coke under an air flow. The performances of Pt and Rh catalysts supported on ceria-zirconia in powder form or deposited on cordierite monoliths are comparatively studied. From these data and calculated thermodynamic equilibrium, the co-existence of thermal and catalytic processes is demonstrated. A stable hydrogen productivity up to circa 18 mmol of H{sub 2} g{sup -1} of bio-oil ({proportional_to}50% H{sub 2} in the gas stream) with a minimized methane formation (ca. 6%) is obtained with the monolith configuration. Both Pt and Rh-based catalysts allow a good control of carbon formation, the coke being fully combusted during the regeneration step. Slow deactivation phenomena and selectivity changes along time on stream, mostly observed for platinum powder samples, are related to changes in catalyst structure and to the peculiar role of oxygen stored in the zirconia-ceria support. The heat balance evaluation of the sequential cracking/regeneration cycle shows that the process could be auto-thermal, i.e., minimizing the energy input, being competitive with conventional steam-reforming process under the same operating temperature. (author)

  16. Nitroaldol reaction over solid base catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Akutu, Kazumasa; Kabashima, Hajime; Seki, Tsunetake; Hattori, Hideshi [Center for Advanced Research of Energy Technology, Hokkaido University, Kita-13, Nishi-8, Kita-ku, Sapporo 060-8628 (Japan)

    2003-07-10

    Nitroaldol reaction of a nitro compound with a carbonyl compound was carried out over a variety of solid base catalysts to elucidate the activity-determining factors in the nature of the catalysts and in the nature of nitro and carbonyl compounds. Among the catalysts examined, MgO, CaO, Ba(OH){sub 2}, KOH/alumina, KF/alumina, Sr(OH){sub 2}, hydrotalcite, and MgCO{sub 3} exhibited high activity for nitroaldol reaction of nitromethane with propionaldehyde, the activities being in this order. Over these catalysts, the yields exceeded 20% at a reaction temperature of 313K and a reaction time of 1h. Mg(OH){sub 2}, {gamma}-alumina, SrO, Ca(OH){sub 2}, BaCO{sub 3}, SrCO{sub 3}, BaO, and La{sub 2}O{sub 3} exhibited moderate activites; the yield were in the range 20-2%. CaCO{sub 3}, ZrO{sub 2}, and ZnO scarcely showed the activity. It is suggested that strongly basic sites are not required for the reaction because the abstraction of a proton from a nitro compound is easy. The reactivities of the nitro compounds were nitroethane > nitromethane > 2-nitropropane, and those of carbonyl compounds were propionaldehyde>isobutyraldehyde>pivalaldehyde>acetone>benzaldehyde>methylpro pionate. On the basis of IR study of adsorbed reactants and the reactivities of the reactants, the reaction mechanisms are proposed. The reaction proceeds by the nucleophilic addition of the carbanion formed by the abstraction of a proton from nitro compounds to the cationic species formed by the adsorption of carbonyl compounds on the acidic sites (metal cations). The nitroaldol reaction of nitromethane with propionaldehyde over MgO was scarcely poisoned by carbon dioxide and water; nitromethane is so acidic that it is able to be adsorbed on the catalyst on which carbon dioxide or water was preadsorbed.

  17. Alkaline ionic liquids applied in supported ionic liquid catalyst for selective hydrogenation of citral to citronellal

    Directory of Open Access Journals (Sweden)

    Eero eSalminen

    2014-02-01

    Full Text Available The challenge in preparation of ionic liquids containing a strong alkaline anion is to identify a suitable cation which can tolerate the harsh conditions induced by the anion. In this study, a commercial quaternary ammonium compound (quat benzalkonium [ADBA] (alkyldimethylbenzylammonium was used as a cation in the synthesis of different alkaline ionic liquids. In fact, the precursor, benzalkonium chloride, is a mixture of alkyldimethylbenzylammonium chlorides of various alkyl chain lengths and is commonly used in the formulation of various antiseptic products. The prepared ionic liquids were utilized as Supported Ionic Liquid Catalysts (SILCAs. Typically, a SILCA contains metal nanoparticles, enzymes or metal complexes in an ionic liquid layer which is immobilized on a solid carrier material such as an active carbon cloth (ACC. The catalysts were applied in the selective hydrogenation of citral to citronellal which is an important perfumery chemical. Interestingly, 70 % molar yield towards citronellal was achieved over a catalyst containing the alkaline ionic liquid benzalkonium methoxide.

  18. Alkaline ionic liquids applied in supported ionic liquid catalyst for selective hydrogenation of citral to citronellal

    Science.gov (United States)

    Salminen, Eero; Virtanen, Pasi; Mikkola, Jyri-Pekka

    2014-02-01

    The challenge in preparation of ionic liquids containing a strong alkaline anion is to identify a suitable cation which can tolerate the harsh conditions induced by the anion. In this study, a commercial quaternary ammonium compound (quat) benzalkonium [ADBA] (alkyldimethylbenzylammonium) was used as a cation in the synthesis of different alkaline ionic liquids. In fact, the precursor, benzalkonium chloride, is a mixture of alkyldimethylbenzylammonium chlorides of various alkyl chain lengths and is commonly used in the formulation of various antiseptic products. The prepared ionic liquids were utilized as Supported Ionic Liquid Catalysts (SILCAs). Typically, a SILCA contains metal nanoparticles, enzymes or metal complexes in an ionic liquid layer which is immobilized on a solid carrier material such as an active carbon cloth (ACC). The catalysts were applied in the selective hydrogenation of citral to citronellal which is an important perfumery chemical. Interestingly, 70 % molar yield towards citronellal was achieved over a catalyst containing the alkaline ionic liquid benzalkonium methoxide.

  19. Effect of Carbon Supported Pt Catalysts on Selective Hydrogenation of Cinnamaldehyde

    Directory of Open Access Journals (Sweden)

    Qing Han

    2016-01-01

    Full Text Available Selective hydrogenation of cinnamaldehyde (CAL to cinnamyl alcohol (COL is of both fundamental and industrial interest. It is of great significance to evaluate the possible differences between different supports arising from metal dispersion and electronic effects, in terms of activity and selectivity. Herein, Pt catalysts on different carbon supports including carbon nanotubes (CNTs and reduced graphene oxides (RGO were developed by a simple wet impregnation method. The resultant catalysts were well characterized by XRD, Raman, N2 physisorption, TEM, and XPS analysis. Applied in the hydrogenation of cinnamaldehyde, 3.5 wt% Pt/CNT shows much higher selectivity towards cinnamyl alcohol (62% than 3.5 wt% Pt/RGO@SiO2 (48%. The enhanced activity can be ascribed to the high graphitization degree of CNTs and high density of dispersed Pt electron cloud.

  20. Synthesis of novel platinum-on-flower-like nickel catalysts and their applications in hydrogenation reaction

    Science.gov (United States)

    Zhu, Lihua; Zheng, Tuo; Zheng, Jinbao; Yu, Changlin; Zhou, Qiongyu; Hua, Jingrong; Zhang, Nuowei; Shu, Qing; Chen, Bing H.

    2017-11-01

    Without any capping agent, surfactant or external magnetic field, hierarchical nickel was successfully prepared via a simple hydrothermal reduction method by using hydrazine hydrate as reducing agent. The structure and morphology of the products (for instance, flower-like, column-like and spherical-like) were controlled by adjusting hydrothermal conditions including reaction temperature and solvent. The morphology transformation mechanism was proposed and discussed. Corresponding platinum/nickel catalysts (Pt/Ni) were obtained by the galvanic replacement reaction method. And the catalytic activity of the platinum/nickel samples was evaluated by using selective hydrogenation of nitrobenzene. It was found that platinum/flower-like nickel showed the most excellent catalytic performance among the as-synthesized catalysts in this work, with good stability as well. Moreover, reasons for the enhancement of platinum/flower-like nickel for nitrobenzene hydrogenation were investigated.

  1. CO{sub 2} HYDROGENATION TO METHANOL ON Cu-ZrO{sub 2} CATALYSTS

    Energy Technology Data Exchange (ETDEWEB)

    F. Bali [Laboratoire de Chimie du Gaz Naturel, Faculte de Chimie. Universite H. Boumediene, Algiers (Algeria); L.Jalowiecki- Duhamel [Unite de Catalyse et Chimie du Solide, Lille (France)

    2008-09-30

    The effective utilization of CO{sub 2} has been catching great attention due to its environmental relevance. In addition, synthesis of methanol from CO{sub 2}+H{sub 2} is one of most economic processes. Therefore, it is important to develop new catalysts with a high activity and selectivity to methanol. In the present study, we report on CO{sub 2} hydrogenation activity and selectivity of zirconium-copper oxides. The characterization of the catalysts in the oxidized and partially reduced state (after treatment in H{sub 2}) using in-situ techniques such as XRD and chemical catalytic hydrogen storage titration, allows proposing a mechanistic model for the formation of methanol and methane related to specific catalytic active sites.

  2. Elucidating the Origin of Hydrogen Evolution Reaction Activity in Mono- and Bimetallic Metal- and Nitrogen-Doped Carbon Catalysts (Me-N-C).

    Science.gov (United States)

    Shahraei, Ali; Moradabadi, Ashkan; Martinaiou, Ioanna; Lauterbach, Stefan; Klemenz, Sebastian; Dolique, Stephanie; Kleebe, Hans-Joachim; Kaghazchi, Payam; Kramm, Ulrike I

    2017-08-02

    In this work, we present a comprehensive study on the role of metal species in MOF-based Me-N-C (mono- and bimetallic) catalysts for the hydrogen evolution reaction (HER). The catalysts are investigated with respect to HER activity and stability in alkaline electrolyte. On the basis of the structural analysis by X-ray diffraction, X-ray-induced photoelectron spectroscopy, and transmission electron microscopy, it is concluded that MeN4 sites seem to dominate the HER activity of these catalysts. There is a strong relation between the amount of MeN4 sites that are formed and the energy of formation related to these sites integrated at the edge of a graphene layer, as obtained from density functional theory (DFT) calculations. Our results show, for the first time, that the combination of two metals (Co and Mo) in a bimetallic (Co,Mo)-N-C catalyst allows hydrogen production with a significantly improved overpotential in comparison to its monometallic counterparts and other Me-N-C catalysts. By the combination of experimental results with DFT calculations, we show that the origin of the enhanced performance of our (Co,Mo)-N-C catalyst seems to be provided by an improved hydrogen binding energy on one MeN4 site because of the presence of a second MeN4 site in its close vicinity, as investigated in detail for our most active (Co,Mo)-N-C catalyst. The outstanding stability and good activity make especially the bimetallic Me-N-C catalysts interesting candidates for solar fuel applications.

  3. Promotion of Ca-Co Bifunctional Catalyst/Sorbent with Yttrium for Hydrogen Production in Modified Chemical Looping Steam Methane Reforming Process

    Directory of Open Access Journals (Sweden)

    Samira Akbari-Emadabadi

    2017-09-01

    Full Text Available In this study, the application of a calcium-based bifunctional catalyst/sorbent is investigated in modified chemical looping steam methane reforming (CLSMR process for in situ CO2 sorption and H2 production. The yttrium promoted Ca-Co samples were synthesized and applied as bifunctional catalysts/sorbent. The influence of reduction temperature (500–750 °C, Ca/Co and Ca/Y ratios (1.5–∞ and 3–18, respectively and catalyst life time are determined in CLSMR process. The physicochemical transformation of fresh, used and regenerated samples after 16 redox cycles are determined using X-ray powder diffraction (XRD, N2 adsorption–desorption, field emission scanning electron microscopy (FESEM, energy dispersive X-ray spectroscopy (EDX and transmission electron microscopy (TEM techniques. The effect of yttrium promoter on the structure of catalyst and regeneration step on the reversibility of bifunctional catalyst/sorbent was two important factors. The characterization results revealed that the presence of yttrium in the structure of Ca-9Co sample could improve the morphology and textural properties of catalyst/sorbents. The suitable reversibility of bifunctional catalyst/sorbents during the repeated cycles is confirmed by characterization of calcined samples. The Ca-9Co-4.5Y as optimal catalyst illustrated superior performance and stability. It showed about 95.8% methane conversion and 82.9% hydrogen yield at 700 °C and stable activity during 16 redox cycles.

  4. On the Role of Surface Modifications of Palladium Catalysts in the Selective Hydrogenation of Acetylene

    DEFF Research Database (Denmark)

    Studt, Felix; Abild-Pedersen, Frank; Bligaard, Thomas

    2008-01-01

    Summing Me up: DFT calculations have shown that alloying, subsurface carbon, and hydride formation, all increase the selectivity of Pd catalysts for acetylene hydrogenation by weakening the surface–adsorbate bond. A simple descriptor—the adsorption energy of a methyl group—has been used to quantify...... and compare the different effects in the adsorption of acetylene and ethylene on various transition-metal surfaces (see picture)....

  5. Microwave-assisted Ni-La/γ-Al2O3 catalyst for benzene hydrogenation

    Science.gov (United States)

    Liu, Xianjun; Liu, Shuzhi; Xu, Peiqiang

    2017-11-01

    A series of Ni-La/γ-Al2O3 catalysts were prepared by adopting the methods of isometric impregnation and microwave impregnation. The catalysts were characterized with XRD, BET, and SEM, respectively. Inspecting the effects of adding La and the methods of impregnation on the hydrogenation activity of catalysts. The results show that adding a moderate amount of La promotes the dispersing of Ni on the carrier, the methods of microwave impregnation weaks the interaction between Ni and the carrier further, inhibits the formation of NiAl2O4, and the activity of catalyst prepared by the methods of microwave impregnation was significantly higher than that prepared by the methods of isometric impregnation. The hydrogenation activity of the Ni-La/γ-Al2O3 (WB) dipped with n(Ni): n(La) = 4: 1, microwave irradiation time 30 min with power 600W as well as calcined at 400°C exhibited the best performance. The conversion rate is 91.21% with reaction conditions: T = 160°C, p = 0.8 MPa, air speed 5 h-1, n(H2): n(benzene) = 2: 1.

  6. Amineborane Based Chemical Hydrogen Storage - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Sneddon, Larry G.

    2011-04-21

    The development of efficient and safe methods for hydrogen storage is a major hurdle that must be overcome to enable the use of hydrogen as an alternative energy carrier. The objectives of this project in the DOE Center of Excellence in Chemical Hydride Storage were both to develop new methods for on-demand, low temperature hydrogen release from chemical hydrides and to design high-conversion off-board methods for chemical hydride regeneration. Because of their reactive protic (N-H) and hydridic (B-H) hydrogens and high hydrogen contents, amineboranes such as ammonia borane, NH3BH3 (AB), 19.6-wt% H2, and ammonia triborane NH3B3H7 (AT), 17.7-wt% H2, were initially identified by the Center as promising, high-capacity chemical hydrogen storage materials with the potential to store and deliver molecular hydrogen through dehydrogenation and hydrolysis reactions. In collaboration with other Center partners, the Penn project focused both on new methods to induce amineborane H2-release and on new strategies for the regeneration the amineborane spent-fuel materials. The Penn approach to improving amineborane H2-release focused on the use of ionic liquids, base additives and metal catalysts to activate AB dehydrogenation and these studies successfully demonstrated that in ionic liquids the AB induction period that had been observed in the solid-state was eliminated and both the rate and extent of AB H2-release were significantly increased. These results have clearly shown that, while improvements are still necessary, many of these systems have the potential to achieve DOE hydrogen-storage goals. The high extent of their H2­-release, the tunability of both their H2 materials weight-percents and release rates, and their product control that is attained by either trapping or suppressing unwanted volatile side products, such as borazine, continue to make AB/ionic­-liquid based systems attractive candidates for chemical hydrogen storage applications. These studies also

  7. A novel nano-Ni/SiO2 catalyst for hydrogen production from steam reforming of ethanol.

    Science.gov (United States)

    Wu, Chunfei; Williams, Paul T

    2010-08-01

    Catalytic steam reforming of ethanol has been regarded as a promising way to produce hydrogen. However, catalytic deactivation is a key problem in the process. In this paper, a novel nano-Ni/SiO2 catalyst was prepared by a simple sol-gel method and compared to catalysts prepared by an impregnation method in relation to the steam reforming ethanol process. Good Ni dispersion and high BET surface areas (>700 m2 g(-1)) were obtained for sol-gel catalysts, whereas only 1 m2 g(-1) surface area was obtained for the Ni/SiO2 impregnation catalyst. The results of catalytic steam reforming of ethanol showed that about twice of the hydrogen production was produced with the Ni/SiO2 catalyst prepared by sol-gel (around 0.2 g h(-1)) compared with that prepared by impregnation (around 0.1 g h(-1)). The analysis of the used catalysts showed that 10Ni/SiO2-B and 20Ni/SiO2-B presented the highest stability, while other catalysts were fragmented into small pieces after the reforming process, especially the catalysts prepared by impregnation. A novel catalyst has been produced that has been shown to be effective in the production of hydrogen from the steam reforming of ethanol.

  8. Late-Transition-Metal-Modified β-Mo 2 C Catalysts for Enhanced Hydrogenation during Guaiacol Deoxygenation

    Energy Technology Data Exchange (ETDEWEB)

    Baddour, Frederick G. [National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States; Witte, Vanessa A. [National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States; Nash, Connor P. [National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States; Griffin, Michael B. [National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States; Ruddy, Daniel A. [National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States; Schaidle, Joshua A. [National Bioenergy Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States

    2017-11-08

    Molybdenum carbide has been identified as a promising bifunctional catalyst in the deoxygenation of a variety of pyrolysis vapor model compounds. Although high deoxygenation activity has been demonstrated, complementary hydrogenation activity has been limited, especially for lignin-derived, aromatic model compounds. The ability to control the relative site densities of acidic and hydrogenation functionalities represents a catalyst design challenge for these materials with the goal to improve hydrogenation activity under ex situ catalytic fast pyrolysis (CFP) conditions. Here we demonstrate that the addition of Pt and Ni to Mo2C resulted in an increase in the H*-site density with only a minor decrease in the acid-site density. In contrast, the addition of Pd did not significantly alter the H* or acid site densities. High conversions (>94%) and high selectivities to 0-oxygen products (>80%) were observed in guaiacol deoxygenation under ex situ CFP conditions (350 degrees C and 0.44 MPa H2) for all catalysts. Pt addition resulted in the greatest deoxygenation, and site-time yields to hydrogenated products over the Pt/Mo2C catalyst were increased to 0.048 s-1 compared to 0.015-0.019 s-1 for all other catalysts. The Pt/Mo2C catalyst demonstrated the highest hydrogenation performance, but modification with Ni also significantly enhanced hydrogenation performance, representing a promising lower-cost alternative.

  9. Bio-inspired MOF-based Catalysts for Lignin Valorization.

    Energy Technology Data Exchange (ETDEWEB)

    Allendorf, Mark D.; Stavila, Vitalie; Ramakrishnan, Parthasarathi; Davis, Ryan Wesley

    2014-09-01

    for the C-O bond hydrogenolysis in model compounds, which mimic the b-O-4, a-O-4, and 4-O-5 linkages of natural lignin. The versatile IRMOF-74(n) series is proposed as a platform for creating efficient hydrogenolysis catalysts as it not only displays tunable pore sizes, but also has the required thermal and chemical stability. The catalytic C-O bond cleavage occurs at 10 bar hydrogen pressure and temperatures as low as 120 degC. The conversion efficiency of the aromatic ether substrates into the corresponding hydrocarbons and phenols varies as PhCH 2 CH 2 OPh > PhCH 2 OPh > PhOPh (Ph = phenyl), while the catalytic activity generally follows the following trend Ni@IRMOF-74>Ti@IRMOF-74>IRMOF-74. Conversions as high as 80%, coupled with good selectivity for hydrogenolysis vs. hydrogenation, highlight the potential of MOF-based catalysts for the selective cleavage of recalcitrant aryl-ether bonds found in lignin and other biopolymers. This project supports the DOE Integrated Biorefinery Program goals, the objective of which is to convert biomass to fuels and high-value chemicals, by addressing an important technology gap: the lack of low-temperature catalysts suitable for industrial lignin degradation. Biomass, which is %7E30 wt% lignin, constitutes a potentially major source of platform chemicals that could improve overall profitability and productivity of all energy-related products, thereby benefiting consumers and reducing national dependence on imported oil. Additionally, DoD has a strong interest in low-cost drop-in fuels (Navy Biofuel Initiative) and has signed a Memorandum of Understanding with DOE and USDA to develop a sustainable biofuels industry.

  10. CO hydrogenation on supported molybdenum catalysts: effects of support on specific activities of reduced and sulfided catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Concha, B.E.; Bartholomew, G.L.; Bartholomew, C.H.

    1984-10-01

    A reaction temperature of 350/sup 0/C was chosen to minimize carbon formation and to allow sufficient conversion of CO. The initial specific activity of Mo/SiO/sub 2/ is significantly higher than that of the other reduced supported catalysts. The order of decreasing specific activity is Mo/SiO/sub 2/ > Mo/Al/sub 2/O/sub 3/ > Mo/C > Mo/CeO/sub 2/. For a reaction period of 20-25 h, the reduced Mo/SiO/sub 2/ activity decreased by 70% compared to 20-30% for the other catalysts. Initial specific activities of MoS/sub 2/ and sulfided Mo/Al/sub 2/O/sub 3/, Mo/SiO/sub 2/, and Mo/CeO/sub 2/ were similar and higher by factors of 6-8 than that of the Mo/C. With the exception of Mo/C, the mass-based activities of the freshly sulfided catalysts correlated linearly with oxygen uptake. Compared to freshly reduced catalysts, the activities of the sulfided Mo/SiO/sub 2/ and Mo/C were lower, that of Mo/Al/sub 2/O/sub 3/ about the same, and that of Mo/CeO/sub 2/ greater. Activities of the sulfided were generally stable during 20-25 h of reaction. 25 references, 1 figure, 2 tables.

  11. Hydrogenation of Anthracene in Supercritical Carbon Dioxide Solvent Using Ni Supported on Hβ-Zeolite Catalyst

    Directory of Open Access Journals (Sweden)

    Ashraf Aly Hassan

    2012-01-01

    Full Text Available Catalytic hydrogenation of anthracene was studied over Ni supported on Hβ-zeolite catalyst under supercritical carbon dioxide (sc-CO2 solvent. Hydrogenation of anthracene in sc-CO2 yielded 100% conversion at 100 °C, which is attributed to the reduced mass transfer limitations, and increased solubility of H2 and substrate in the reaction medium. The total pressure of 7 MPa was found to be optimum for high selectivity of octahydroanthracene (OHA. The conversion and selectivity for OHA increased with an increase in H2 partial pressure, which is attributed to higher concentration of hydrogen atoms at higher H2 pressures. The selectivity reduced the pressure below 7 MPa because of enhanced desorption of the tetrahydro-molecules and intermediates from Ni active sites, due to higher solubility of the surface species in sc-CO2. The selectivity of OHA increased with the increase in catalyst weight and reaction time. The rate of hydrogenation of anthracene was compared with that found for napthalene and phenanthrene. The use of acetonitrile as co-solvent or expanded liquid with CO2 decreased the catalytic activity.

  12. Hydrogen production from glycerol on Ni/Al{sub 2}O{sub 3} catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, Esteban A.; D' Angelo, Miguel A.; Comelli, Raul A. [Instituto de Investigaciones en Catalisis y Petroquimica - INCAPE (F.I.Q.-U.N.L., CONICET), Santiago del Estero 2654, S3000AOJ - Santa Fe (Argentina)

    2010-06-15

    The growing demand of hydrogen needs renewable sources of raw materials to produce it. Glycerol, by-product of biodiesel synthesis, could be a bio-renewable substrate to obtain hydrogen. A Ni(5.8%)-alumina catalyst was evaluated in the steam reforming of glycerol at 600-700 C, atmospheric pressure, 16:1 water:glycerol molar ratio, and 3.4-10.0 h{sup -1} WHSV. A glycerol aqueous solution was fed, while a nitrogen stream was co-fed. After 4 h-on-stream, conversion was 96.8% at 600 C increasing to 99.4% at 700 C, reaching the largest hydrogen selectivity (99.7%) at 650 C. After 8 h, conversion decreases more significantly at 600 C, while the hydrogen selectivity does not significantly change with temperature and increases by decreasing WHSV. After 4 h, the main by-product was methane (76-97%), increasing at higher temperature, followed by ethene, ethane, propene, and propane. At 700 C and 10.0 h{sup -1} WHSV, the main by-products were ethene (47%) and methane (37%); it could be associated to catalyst deactivation. (author)

  13. A kinetic study on the adsorption and reaction of hydrogen over silica-supported ruthenium and silver-ruthenium catalysts during the hydrogenation of carbon monoxide

    Energy Technology Data Exchange (ETDEWEB)

    VanderWiel, David P. [Iowa State Univ., Ames, IA (United States)

    1999-02-12

    Although the catalytic hydrogenation of carbon monoxide has been a subject of considerable investigation for many years, its increasing economical attractiveness as an industrial source of hydrocarbons has recently led to a search for more active and selective catalysts. A fundamental problem in the development of such catalysts is an incomplete knowledge of the operative surface processes, due in large part to the inability to accurately measure surface concentrations of reactant species during reaction. Specifically, the concentration of surface hydrogen proves difficult to estimate using normally revealing techniques such as transient isotopic exchange due to kinetic isotope effects. Knowledge of such concentrations is essential to the determination of the mechanisms of adsorption and reaction, since many kinetic parameters are concentration dependent. It is the aim of this research to investigate the mechanism and kinetics of the adsorption and reaction of hydrogen on silica-supported ruthenium and silver-ruthenium catalysts during the hydrogenation of carbon monoxide. By preadsorbing carbon monoxide onto the surface of ruthenium and silver-ruthenium catalysts, the kinetics of hydrogen adsorption and reaction can be monitored upon exposure of this surface to ambient hydrogen gas. This is accomplished by conducting identical experiments on two separate systems. First, the formation of methane is monitored using mass spectroscopy, and specific reaction rates and apparent activation energies are measured. Next, in situ 1H-NMR is used to monitor the amount of hydrogen present on the catalyst surface during adsorption and reaction. The results for these two sets of experiments are then combined to show a correlation between the rate of reaction and the surface hydrogen concentration. Finally, transition state theory is applied to this system and is used to explain the observed change in the apparent activation energy. The structure sensitivity of hydrogen

  14. Complex of titanocene with tolan as a catalyst for the homogeneous hydrogenation of unsaturated compounds

    Energy Technology Data Exchange (ETDEWEB)

    Shur, V.B.; Burlakov, V.V.; Vol' pin, M.E.

    1986-09-01

    The complex of titanocene with tolan (Cp/sub 2/Ti(C/sub 2/Ph/sub 2/)) (I) synthesized by the reaction of Cp/sub 2/TiCl/sub 2/ with magnesium and tolan in THF was found to be an effective catalyst for the homogeneous hydrogenation of olefins and acetylenes at 20 C atmospheric hydrogen pressure. The reaction was carried out with a substrate. Under the conditions of the experiment, tolan as well as cis- and trans-stilbenes are hydrogenated virtually quantitatively in a few minutes to dibenzyl. Similarly, styrene is converted to ethylbenzene, 3-hexyne is converted to hexane, 1-heptene is converted to heptane, cyclohexene is converted to cyclohexane, and trans, trans-1,4-diphenyl-1,3-butadiene is converted to 1,4-diphenylbutane. The authors' attempts to synthesize (Cp/sub 2/Ti(C/sub 2/Ph/sub 2/)) with tolan were unsucessful.

  15. Highly Selective TiN-Supported Highly Dispersed Pt Catalyst: Ultra Active toward Hydrogen Oxidation and Inactive toward Oxygen Reduction.

    Science.gov (United States)

    Luo, Junming; Tang, Haibo; Tian, Xinlong; Hou, Sanying; Li, Xiuhua; Du, Li; Liao, Shijun

    2018-01-31

    The severe dissolution of the cathode catalyst, caused by an undesired oxygen reduction reaction at the anode during startup and shutdown, is a fatal challenge to practical applications of polymer electrolyte membrane fuel cells. To address this important issue, according to the distinct structure-sensitivity between the σ-type bond in H 2 and the π-type bond in O 2 , we design a HD-Pt/TiN material by highly dispersing Pt on the TiN surface to inhibit the unwanted oxygen reduction reaction. The highly dispersed Pt/TiN catalyst exhibits excellent selectivity toward hydrogen oxidation and oxygen reduction reactions. With a Pt loading of 0.88 wt %, our catalyst shows excellent hydrogen oxidation reaction activity, close to that of commercial 20 wt % Pt/C catalyst, and much lower oxygen reduction reaction activity than the commercial 20 wt % Pt/C catalyst. The lack of well-ordered Pt facets is responsible for the excellent selectivity of the HD-Pt/TiN materials toward hydrogen oxidation and oxygen reduction reactions. Our work provides a new and cost-effective solution to design selective catalysts toward hydrogen oxidation and oxygen reduction reactions, making the strategy of using oxygen-tolerant anode catalyst to improve the stability of polymer electrolyte membrane fuel cells during startup and shutdown more affordable and practical.

  16. Direct methanol steam reforming to hydrogen over CuZnGaOx catalysts without CO post-treatment: mechanistic considerations.

    Science.gov (United States)

    Tong, Weiyi; Cheung, Kevin; West, Adam; Yu, Kai-Man; Tsang, Shik Chi Edman

    2013-05-21

    Utilization of hydrogen gas (and carbon dioxide) from methanol steam reforming reaction directly without CO post-treatment to supply proton exchange membrane fuel cells for mobile applications is an attractive option. CuZnGaOx based mixed oxides prepared by co-precipitation are found to be active as catalysts for the reforming reaction. It is also found that the use of lower temperature and a faster substrate flow rate with a shorter contact time with the catalyst bed can significantly reduce the CO level in the product gas stream. At 150 °C this class of oxides gives a decent methanol conversion but can also totally suppress the CO production at a short contact time, which is in a sharp contrast with conventional CuZnOx based catalysts that give a significant degree of CO formation. Characterization using Diffuse Reflectance Infrared Fourier Transform (DRIFT) analysis presented in this work clearly suggests the importance of the interface between copper metal-defective oxides for the catalysis. Mechanistic aspects of this reaction are therefore discussed in this paper.

  17. The synergistic effect of catalysts on hydrogen desorption properties of MgH2–TiO2–NiO nanocomposite

    Directory of Open Access Journals (Sweden)

    Farshad Rajabpour

    2016-10-01

    Full Text Available Abstract The high desorption temperature and slow desorption kinetics of MgH2 makes it less competitive for future mobile applications; using a catalyst accompanied by mechanical milling seems to be a good solution to overcome those problems. Therefore, the addition of TiO2 and NiO to MgH2 accompanied by 15 h of mechanical milling was considered in this study. The phase constituent and hydrogen desorption of the powder mixture were investigated using X-ray diffraction (XRD and a Sievert-type apparatus, respectively. XRD results showed that after milling, no binary or ternary compounds were formed, but hydrogen desorption time decreased and the desorbed hydrogen content increased. It seems that the increase in desorbed hydrogen was related to the simultaneous catalytic effect of TiO2 and NiO as well as mechanical milling. The results showed that the addition of both catalysts can improve the hydrogen desorption behavior of MgH2-based nanocomposite compared to the addition of only one catalyst of the same amount.

  18. Hydrogen Production via Glycerol Dry Reforming over La-Ni/Al2O3 Catalyst

    Directory of Open Access Journals (Sweden)

    Kah Weng Siew

    2013-12-01

    Full Text Available Glycerol (a bio-waste generated from biodiesel production has been touted as a promising bio-syngas precursor via reforming route. Previous studies have indicated that carbon deposition is the major performance-limiting factor for nickel (Ni catalyst during glycerol steam reforming. In the current paper, dry (CO2-reforming of glycerol, a new reforming route was carried out over alumina (Al2O3-supported non-promoted and lanthanum-promoted Ni catalysts. Both sets of catalysts were synthesized via wet co-impregnation procedure. The physicochemical characterization of the catalyst showed that the promoted catalyst possessed smaller metal crystallite size, hence higher metal dispersion compared to the virgin Ni/Al2O3 catalyst. This was also corroborated by the surface images captured by the FESEM analysis. In addition, BET surface area measurement gave 92.05m²/g for non-promoted Ni catalyst whilst promoted catalysts showed an average of 1 to 6% improvement depending on the La loading. Reaction studies at 873 K showed that glycerol dry reforming successfully produced H2 with glycerol conversion and H2 yield that peaked at 9.7% and 25% respectively over 2wt% La content. The optimum catalytic performance by 2%La-Ni/Al2O3 can be attributed to the larger BET surface area and smaller crystallite size that ensured accessibility of active catalytic sites.  © 2013 BCREC UNDIP. All rights reservedReceived: 12nd May 2013; Revised: 7th October 2013; Accepted: 16th October 2013[How to Cite: Siew, K.W., Lee, H.C., Gimbun, J., Cheng, C.K. (2013. Hydrogen Production via Glycerol Dry Reforming over La-Ni/Al2O3 Catalyst. Bulletin of Chemical Reaction Engineering & Catalysis, 8 (2: 160-166. (doi:10.9767/bcrec.8.2.4874.160-166][Permalink/DOI: http://dx.doi.org/10.9767/bcrec.8.2.4874.160-166

  19. Hydrothermal Synthesis of Co-Ru Alloy Particle Catalysts for Hydrogen Generation from Sodium Borohydride

    Directory of Open Access Journals (Sweden)

    Marija Kurtinaitienė

    2013-01-01

    Full Text Available We report the synthesis of μm and sub-μm-sized Co, Ru, and Co-Ru alloy species by hydrothermal approach in the aqueous alkaline solutions (pH ≥ 13 containing CoCl2 and/or RuCl3, sodium citrate, and hydrazine hydrate and a study of their catalytic properties for hydrogen generation by hydrolysis of sodium borohydride solution. This way provides a simple platform for fabrication of the ball-shaped Co-Ru alloy catalysts containing up to 12 wt% Ru. Note that bimetallic Co-Ru alloy bowls containing even 7 at.% Ru have demonstrated catalytic properties that are comparable with the ones of pure Ru particles fabricated by the same method. This result is of great importance in view of the preparation of cost-efficient catalysts for hydrogen generation from borohydrides. The morphology and composition of fabricated catalyst particles have been characterized using scanning electron microscopy, energy dispersive X-ray diffraction, and inductively coupled plasma optical emission spectrometry.

  20. Two-dimensional metallic tantalum disulfide as a hydrogen evolution catalyst.

    Science.gov (United States)

    Shi, Jianping; Wang, Xina; Zhang, Shuai; Xiao, Lingfeng; Huan, Yahuan; Gong, Yue; Zhang, Zhepeng; Li, Yuanchang; Zhou, Xiebo; Hong, Min; Fang, Qiyi; Zhang, Qing; Liu, Xinfeng; Gu, Lin; Liu, Zhongfan; Zhang, Yanfeng

    2017-10-16

    Two-dimensional metallic transition metal dichalcogenides are emerging as prototypes for uncovering fundamental physical phenomena, such as superconductivity and charge-density waves, as well as for engineering-related applications. However, the batch production of such envisioned transition metal dichalcogenides remains challenging, which has hindered the aforementioned explorations. Herein, we fabricate thickness-tunable tantalum disulfide flakes and centimetre-sized ultrathin films on an electrode material of gold foil via a facile chemical vapour deposition route. Through temperature-dependent Raman characterization, we observe the transition from nearly commensurate to commensurate charge-density wave phases with our ultrathin tantalum disulfide flakes. We have obtained high hydrogen evolution reaction efficiency with the as-grown tantalum disulfide flakes directly synthesized on gold foils comparable to traditional platinum catalysts. This work could promote further efforts for exploring new efficient catalysts in the large materials family of metallic transition metal dichalcogenides, as well as exploiting their applications towards more versatile applications.Metallic transition metal dichalcogenides are important materials for catalysis, but scalable and controllable preparation methods are scarce. Here, the authors synthesize 2H-TaS2 as centimetre-scale films of tunable thickness and show they are an efficient catalyst for hydrogen evolution.

  1. Electro-catalysts for hydrogen production from ethanol for use in SOFC anodes

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Marcos Aurelio da; Paz Fiuza, Raigenis da; Guedes, Bruna C.; Pontes, Luiz A.; Boaventura, Jaime Soares [UFBA, Salvador, Bahia (Brazil). Energy and Materials Science Group

    2010-07-01

    Nickel and cobalt catalysts, supported on YSZ, were prepared by wet impregnation, with and without citric acid; the metal load was 10 and 35% by weight. The catalyst composition was studied by XRF, XPS and SEM-EDS. At low metal concentration, the results of these techniques presented comparables figures; at high concentration, SEM-EDS suggested a non-uniform distribution. The analysis showed that the solids were mixed oxides and formed an alloy after reduction. The surface passivation was possible under controlled conditions. The catalytic test with the steam reforming of ethanol indicated that the metal load had almost no effect on the catalytic activity, but decreased its selectivity. Afterwards, a unitary SOFC was prepared with deposition of the cathode layer. AFM and EIS were used for the characterization of SOFC components. They showed that the electro-catalyst surface was almost all covered with the metal phase, including the large pore walls of the anode. The YSZ phase dominates the material conductance of the complete SOFC assembly (anode/electrolyte/cathode). The unitary SOFC was tested with hydrogen, gaseous ethanol or natural gas; the SOFC operating with ethanol and hydrogen fuel presented virtually no over-potential. (orig.)

  2. Catalytic activity of mono and bimetallic Zn/Cu/MWCNTs catalysts for the thermocatalyzed conversion of methane to hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Erdelyi, B. [Department of Physical Chemistry, Faculty of Science, P.J. Šafárik University, Moyzesova 11, 041 54 Košice (Slovakia); Institute of Physics, Faculty of Science, P.J. Šafárik University, Park Angelium 9, 040 01 Košice (Slovakia); Oriňak, A., E-mail: andrej.orinak@upjs.sk [Department of Physical Chemistry, Faculty of Science, P.J. Šafárik University, Moyzesova 11, 041 54 Košice (Slovakia); Oriňaková, R. [Department of Physical Chemistry, Faculty of Science, P.J. Šafárik University, Moyzesova 11, 041 54 Košice (Slovakia); Lorinčík, J. [Research Center Rez, Hlavní 130, 250 68 Husinec-Řež (Czech Republic); Jerigová, M. [Department of Physical Chemistry, Comenius University, Mlynská dolina 842 15 Bratislava 4 (Slovakia); Velič, D. [Department of Physical Chemistry, Comenius University, Mlynská dolina 842 15 Bratislava 4 (Slovakia); International Laser Centre, Ilkovičová 3, 841 01 Bratislava (Slovakia); Mičušík, M. [Polymer institute, Slovak Academy of Sciences, Dubravská cesta 9, 84541 Bratislava (Slovakia); and others

    2017-02-28

    Highlights: • Zn/Cu/MWCNTs catalyst with good activity. • Methane conversion to hydrogen with high effectivity. • ZnO/Cu responsible for catalytic activity. - Abstract: Mono and bimetallic multiwalled carbon nanotubes (MWCNTs) fortified with Cu and Zn metal particles were studied to improve the efficiency of the thermocatalytic conversion of methane to hydrogen. The surface of the catalyst and the dispersion of the metal particles were studied by scanning electron microscopy (SEM), secondary ion mass spectrometry (SIMS) and with energy-dispersive X-ray spectroscopy (EDS). It was confirmed that the metal particles were successfully dispersed on the MWCNT surface and XPS analysis showed that the Zn was oxidised to ZnO at high temperatures. The conversion of methane to hydrogen during the catalytic pyrolysis was studied by pyrolysis gas chromatography using different amounts of catalyst. The best yields of hydrogen were obtained using pyrolysis conditions of 900 °C and 1.2 mg of Zn/Cu/MWCNT catalyst for 1.5 mL of methane.The initial conversion of methane to hydrogen obtained with Zn/Cu/MWCNTs was 49%, which represent a good conversion rate of methane to hydrogen for a non-noble metal catalyst.

  3. Nonlinear behavior during NO2 hydrogenation on a nanosized Pt-Rh catalyst sample

    Science.gov (United States)

    Barroo, Cédric; De Decker, Yannick; Jacobs, Luc; de Bocarmé, Thierry Visart

    2017-08-01

    Automotive pollution control crucially relies on the reactivity of metal alloy catalysts. Understanding how the chemistry of an alloy compares with that of pure metals forms a decisive step towards the rational development of applied formulations of such catalysts. In this context, we studied the hydrogenation of NO2 on Pt-Rh catalysts at the nanoscale with field emission microscopy (FEM). Previous studies have shown the presence of complex reaction kinetics at the surface of Pt for this reaction, including periodic oscillations at 390 K. As we briefly show here, similar kinetics can also be observed on Rh at higher temperatures. The alloy samples (Pt-17.4 at.%Rh) show signs of important reactivity and associated nonlinear dynamics in an intermediate temperature range. In particular, at 425 K isothermal oscillations are observed on this specific alloy catalyst. The role of the alloy composition on the window of reactivity is explained with a simple theoretical model for the kinetics of the reaction.

  4. Novel catalysts for hydrogen fuel cell applications:Final report (FY03-FY05).

    Energy Technology Data Exchange (ETDEWEB)

    Thornberg, Steven Michael; Coker, Eric Nicholas; Jarek, Russell L.; Steen, William Arthur

    2005-12-01

    The goal of this project was to develop novel hydrogen-oxidation electrocatalyst materials that contain reduced platinum content compared to traditional catalysts by developing flexible synthesis techniques to fabricate supported catalyst structures, and by verifying electrochemical performance in half cells and ultimately laboratory fuel cells. Synthesis methods were developed for making small, well-defined platinum clusters using zeolite hosts, ion exchange, and controlled calcination/reduction processes. Several factors influence cluster size, and clusters below 1 nm with narrow size distribution have been prepared. To enable electrochemical application, the zeolite pores were filled with electrically-conductive carbon via infiltration with carbon precursors, polymerization/cross-linking, and pyrolysis under inert conditions. The zeolite host was then removed by acid washing, to leave a Pt/C electrocatalyst possessing quasi-zeolitic porosity and Pt clusters of well-controlled size. Plotting electrochemical activity versus pyrolysis temperature typically produces a Gaussian curve, with a peak at ca. 800 C. The poorer relative performances at low and high temperature are due to low electrical conductivity of the carbon matrix, and loss of zeolitic structure combined with Pt sintering, respectively. Cluster sizes measured via adsorption-based methods were consistently larger than those observed by TEM and EXAFS, suggesting , that a fraction of the clusters were inaccessible to the fluid phase. Detailed EXAFS analysis has been performed on selected catalysts and catalyst precursors to monitor trends in cluster size evolution, as well as oxidation states of Pt. Experiments were conducted to probe the electroactive surface area of the Pt clusters. These Pt/C materials had as much as 110 m{sup 2}/g{sub pt} electroactive surface area, an almost 30% improvement over what is commercially (mfg. by ETEK) available (86 m{sup 2}/g{sub pt}). These Pt/C materials also perform

  5. Strategies for improving the performance and stability of Ni-based catalysts for reforming reactions.

    Science.gov (United States)

    Li, Shuirong; Gong, Jinlong

    2014-11-07

    Owing to the considerable publicity that has been given to petroleum related economic, environmental, and political problems, renewed attention has been focused on the development of highly efficient and stable catalytic materials for the production of chemical/fuel from renewable resources. Supported nickel nanoclusters are widely used for catalytic reforming reactions, which are key processes for generating synthetic gas and/or hydrogen. New challenges were brought out by the extension of feedstock from hydrocarbons to oxygenates derivable from biomass, which could minimize the environmental impact of carbonaceous fuels and allow a smooth transition from fossil fuels to a sustainable energy economy. This tutorial review describes the recent efforts made toward the development of nickel-based catalysts for the production of hydrogen from oxygenated hydrocarbons via steam reforming reactions. In general, three challenges facing the design of Ni catalysts should be addressed. Nickel nanoclusters are apt to sinter under catalytic reforming conditions of high temperatures and in the presence of steam. Severe carbon deposition could also be observed on the catalyst if the surface carbon species adsorbed on metal surface are not removed in time. Additionally, the production of hydrogen rich gas with a low concentration of CO is a challenge using nickel catalysts, which are not so active in the water gas shift reaction. Accordingly, three strategies were presented to address these challenges. First, the methodologies for the preparation of highly dispersed nickel catalysts with strong metal-support interaction were discussed. A second approach-the promotion in the mobility of the surface oxygen-is favored for the yield of desired products while promoting the removal of surface carbon deposition. Finally, the process intensification via the in situ absorption of CO2 could produce a hydrogen rich gas with low CO concentration. These approaches could also guide the design

  6. The use of ultrasmall iron(0) nanoparticles as catalysts for the selective hydrogenation of unsaturated C-C bonds.

    Science.gov (United States)

    Kelsen, Vinciane; Wendt, Bianca; Werkmeister, Svenja; Junge, Kathrin; Beller, Matthias; Chaudret, Bruno

    2013-04-28

    The performance of well-defined ultrasmall iron(0) nanoparticles (NPs) as catalysts for the selective hydrogenation of unsaturated C-C and C=X bonds is reported. Monodisperse iron nanoparticles of about 2 nm size are synthesized by the decomposition of {Fe(N[Si(CH3)3]2)2}2 under dihydrogen. They are found to be active for the hydrogenation of various alkenes and alkynes under mild conditions and weakly active for C=O bond hydrogenation.

  7. Modeling and simulation of graphene/palladium catalyst reformer for hydrogen generation from waste of IC engine

    Science.gov (United States)

    Rahman, A.; Aung, K. M.

    2018-01-01

    A small amount of hydrogen made by on-board reformer is added to the normal intake air and gasoline mixture in the vehicle’s engine could improves overall combustion quality by allowing nearly twice as much air for a given amount of fuel introduced into the combustion chamber. This can be justified based on the calorific value of Hydrogen (H2) 141.9 MJ/kg while the gasoline (C6.4H11.8) is 47MJ/kg. Different weight % of Pd and GO uses for the reformer model and has conducted simulation by COMSOL software. The best result found for the composition of catalyst (palladium 30% and graphene 70%). The study shows that reformer yield hydrogen 23% for the exhaust temperature of 600-900°C and 20% for 80-90°C. Pumping hydrogen may boost the fuel atomization and vaporization at engine idle condition, which could enhances the fuel combustion efficiency. Thus, this innovative technology would be able to save fuel about 12% and reduce the emission about 35%.

  8. CO{sub x}-free hydrogen and carbon nanofibers production by methane decomposition over nickel-alumina catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Bayat, Nima; Rezaei, Mehran; Meshkani, Fereshteh [Faculty of Engineering, University of Kashan, Kashan (Iran, Islamic Republic of)

    2016-02-15

    Nickel catalysts supported on mesoporous nanocrystalline gamma alumina with various nickel loadings were prepared and employed for thermocatalytic decomposition of methane into CO{sub x}-free hydrogen and carbon nanofibers. The prepared catalysts with different nickel contents exhibited mesoporous structure with high surface area in the range of 121.3 to 66.2m{sup 2}g{sup -1}. Increasing in nickel content decreased the pore volume and increased the crystallite size. The catalytic results revealed that the nickel content and operating temperature both play important roles on the catalytic performance of the prepared catalysts. The results showed that increasing in reaction temperature increased the initial conversion of catalysts and significantly decreased the catalyst lifetime. Scanning electron microscopy (SEM) analysis of the spent catalysts evaluated at different temperatures revealed the formation of intertwined carbon filaments. The results showed that increasing in reaction temperature decreased the diameters of nanofibers and increased the formation of encapsulating carbon.

  9. Phase-Contact Engineering in Mono- and Bimetallic Cu-Ni Co-catalysts for Hydrogen Photocatalytic Materials.

    Science.gov (United States)

    Muñoz-Batista, Mario J; Motta Meira, Debora; Colón, Gerardo; Kubacka, Anna; Fernández-García, Marcos

    2018-01-26

    Understanding how a photocatalyst modulates its oxidation state, size, and structure during a photocatalytic reaction under operando conditions is strongly limited by the mismatch between (catalyst) volume sampled by light and, to date, the physicochemical techniques and probes employed to study them. A synchrotron micro-beam X-ray absorption spectroscopy study together with the computational simulation and analysis (at the X-ray cell) of the light-matter interaction occurring in powdered TiO2 -based monometallic Cu, Ni and bimetallic CuNi catalysts for hydrogen production from renewables was carried out. The combined information unveils an unexpected key catalytic role involving the phase contact between the reduced and oxidized non-noble metal phases in all catalysts and, additionally, reveals the source of the synergistic Cu-Ni interaction in the bimetallic material. The experimental method is applicable to operando studies of a wide variety of photocatalytic materials. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. PVP-Stabilized Palladium Nanoparticles in Silica as Effective Catalysts for Hydrogenation Reactions

    Directory of Open Access Journals (Sweden)

    Caroline Pires Ruas

    2013-01-01

    Full Text Available Palladium nanoparticles stabilized by poly (N-vinyl-2-pyrrolidone (PVP can be synthesized by corresponding Pd(acac2 (acac = acetylacetonate as precursor in methanol at 80°C for 2 h followed by reduction with NaBH4 and immobilized onto SiO2 prepared by sol-gel process under acidic conditions (HF or HCl. The PVP/Pd molar ratio is set to 6. The effect of the sol-gel catalyst on the silica morphology and texture and on Pd(0 content was investigated. The catalysts prepared (ca. 2% Pd(0/SiO2/HF and ca. 0,3% Pd(0/SiO2/HCl were characterized by TEM, FAAS, and SEM-EDS. Palladium nanoparticles supported in silica with a size 6.6 ± 1.4 nm were obtained. The catalytic activity was tested in hydrogenation of alkenes.

  11. Hydrogen production by oxidative reforming of hexadecane over Ni and Pt catalysts supported on Ce/La-doped Al{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Navarro, R.M.; Alvarez-Galvan, M.C.; Fierro, J.L.G. [Instituto de Catalisis y Petroleoquimica (CSIC), C/Marie Curie 2, Cantoblanco 28049, Madrid (Spain); Rosa, F. [Centro de experimentacion de ' El Arenosillo' (CEDEA), Instituto Nacional de Tecnica Aeroespacial (INTA), Ctra. de San Juan del Puerto-Matalascanas km 31, 21130 Mazagon-Moguer (Spain)

    2006-01-04

    The activity and selectivity to hydrogen of alumina-supported nickel or platinum catalysts doped with Ce and La for the oxidative reforming of hexadecane were studied. The influence of both thermal stabilizer and activity promoter, such as lanthanum and cerium oxide, respectively, over hydrogen yield and catalyst durability was investigated. Catalytic activity was found to depend strongly on the type of metal, platinum showing lower specific activities per atom of metal exposed and a higher selectivity to combustion products than the Ni counterparts. The characterization results achieved with H{sub 2} chemisorption, XRD, TPR and XPS showed differences in surface metal concentrations and metal-support interactions which depend on the presence of cerium and/or lanthanum in the support composition. For both based metal catalysts higher reforming activities were found when active metals were deposited on Ce-La-Al{sub 2}O{sub 3} substrate. For Pt-based catalysts, the increase in activity observed for the sample using Ce-La-modified alumina as support is suggested to be related with a participation of lanthanum in the reaction more than modifications on coke resistance or dispersion and state of platinum-induced by lanthanum. In the case of Ni-based catalysts, a lower carbon deposition and a higher thermal stability of metallic Ni particles under reaction conditions were observed for catalyst using Ce-La-modified alumina as support. It is suggested that the higher number of Ni-Ce and Ni-Al surface interactions developed Ce-La-Al{sub 2}O{sub 3}-supported Ni catalysts are responsible of the better catalytic behaviour of this sample in the oxidative reforming of hexadecane.

  12. Solar based hydrogen production systems

    CERN Document Server

    Dincer, Ibrahim

    2013-01-01

    This book provides a comprehensive analysis of various solar based hydrogen production systems. The book covers first-law (energy based) and second-law (exergy based) efficiencies and provides a comprehensive understanding of their implications. It will help minimize the widespread misuse of efficiencies among students and researchers in energy field by using an intuitive and unified approach for defining efficiencies. The book gives a clear understanding of the sustainability and environmental impact analysis of the above systems. The book will be particularly useful for a clear understanding

  13. Carbon-Nanotube-Supported Bio-Inspired Nickel Catalyst and Its Integration in Hybrid Hydrogen/Air Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Gentil, Solène [Univ. Grenoble Alpes, CNRS, DCM UMR 5250, 38000 Grenoble France; Laboratoire de Chimie et Biologie des Métaux, Univ. Grenoble Alpes, CNRS UMR5249, CEA, 38000 Grenoble France; Lalaoui, Noémie [Univ. Grenoble Alpes, CNRS, DCM UMR 5250, 38000 Grenoble France; Dutta, Arnab [Pacific Northwest National Laboratory, Richland WA 99532 USA; Current address: Chemistry Department, IIT Gandhinagar, Gujarat 382355 India; Nedellec, Yannig [Univ. Grenoble Alpes, CNRS, DCM UMR 5250, 38000 Grenoble France; Cosnier, Serge [Univ. Grenoble Alpes, CNRS, DCM UMR 5250, 38000 Grenoble France; Shaw, Wendy J. [Pacific Northwest National Laboratory, Richland WA 99532 USA; Artero, Vincent [Laboratoire de Chimie et Biologie des Métaux, Univ. Grenoble Alpes, CNRS UMR5249, CEA, 38000 Grenoble France; Le Goff, Alan [Univ. Grenoble Alpes, CNRS, DCM UMR 5250, 38000 Grenoble France

    2017-01-12

    A biomimetic nickel bis-diphosphine complex incorporating the amino-acid arginine in the outer coordination sphere, was immobilized on modified single-wall carbon nanotubes (SWCNTs) through electrostatic interactions. The sur-face-confined catalyst is characterized by a reversible 2-electron/2-proton redox process at potentials close to the equibrium potential of the H+/H2 couple. Consequently, the functionalized redox nanomaterial exhibits reversible electrocatalytic activity for the H2/2H+ interconversion over a broad range of pH. This system exhibits catalytic bias, analogous to hydrogenases, resulting in high turnover frequencies at low overpotentials for electrocatalytic H2 oxida-tion between pH 0 and 7. This allowed integrating such bio-inspired nanomaterial together with a multicopper oxi-dase at the cathode side in a hybrid bioinspired/enzymatic hydrogen fuel cell. This device delivers ~2 mW cm–2 with an open-circuit voltage of 1.0 V at room temperature and pH 5, which sets a new efficiency record for a bio-related hydrogen fuel cell with base metal catalysts.

  14. Nickel phosphide nanoparticles decorated nitrogen and phosphorus co-doped porous carbon as efficient hybrid catalyst for hydrogen evolution

    Science.gov (United States)

    Lin, Yan; Zhang, Jun; Pan, Yuan; Liu, Yunqi

    2017-11-01

    The design of efficient and robust Ni2P-based hybrid catalysts for hydrogen evolution reaction (HER) is still in challenge. In this work, a hybrid catalyst composed of monodispersed Ni2P nanoparticles (NPs) and N, P co-doped porous carbon (NPPC) was synthesized through a facile thermal decomposition and used as an efficient electrocatalyst for the HER in 0.5 M H2SO4 solution. Series technologies including X-ray diffraction, Raman, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and N2 sorption are used to characterize the as-synthesized catalysts. The electrochemisty experiments suggested that the as-synthesized Ni2P/NPPC displayed efficient electrocatalytic performance with a low onset overpotential (51 mV), small Tafel slope (74 mV dec-1), high exchange current density (0.12 mA cm-2), large electrochemical double-layer capacitance (21.97 mF cm-2) and high conductivity for the HER. The needed overpotentials are 159 and 184 mV to reach to the current density of 10 and 20 mA cm-2, respectively. Simultaneously, Ni2P/NPPC also displayed good stability in acid solution. The more defects and active sites on the porous carbon which are offered by the co-doped N and P atoms as well as the synergistic effect between NPPC and Ni2P NPs are contributed to the excellent catalytic performance for HER. The current study suggests that introducing the N, P heteroatoms co-doped carbon materials to the Ni2P-based catalysts could enhance HER electrocatalytic performance efficiently.

  15. Supercritical water gasification of landfill leachate for hydrogen production in the presence and absence of alkali catalyst.

    Science.gov (United States)

    Weijin, Gong; Binbin, Li; Qingyu, Wang; Zuohua, Huang; Liang, Zhao

    2018-03-01

    Gasification of landfill leachate in supercritical water using batch-type reactor is investigated. Alkali such as NaOH, KOH, K 2 CO 3 , Na 2 CO 3 is used as catalyst. The effect of temperature (380-500 °C), retention time (5-25 min), landfill leachate concentration (1595 mg L -1 -15,225 mg L -1 ), catalyst adding amount (1-10 wt%) on hydrogen mole fraction, hydrogen yield, carbon gasification rate, COD, TOC, TN removal efficiency are investigated. The results showed that gaseous products mainly contained hydrogen, methane, carbon dioxide and carbon monoxide without addition of catalyst. However, the main gaseous products are hydrogen and methane with addition of NaOH, KOH, K 2 CO 3 , Na 2 CO 3 . In the absence of alkali catalyst, the effect of temperature on landfill leachate gasification is positive. Hydrogen mole fraction, hydrogen yield, carbon gasification ratio increase with temperature, which maximum value being 55.6%, 107.15 mol kg -1 , 71.96% is obtained at 500 °C, respectively. Higher raw landfill leachate concentration leads to lower hydrogen production and carbon gasification rate. The suitable retention time is suggested to be 15 min for higher hydrogen production and carbon gasification rate. COD, TOC and TN removal efficiency also increase with increase of temperature, decrease of landfill leachate concentration. In the presence of catalyst, the hydrogen production is obviously promoted by addition of alkali catalyst. the effect of catalysts on hydrogen production is in the following order: NaOH > KOH > Na 2 CO 3  > K 2 CO 3 . The maximum hydrogen mole fraction and hydrogen yield being 74.40%, 70.05 mol kg -1 is obtained with adding amount of 5 wt% NaOH at 450 °C, 28 MPa, 15 min. Copyright © 2017. Published by Elsevier Ltd.

  16. Influences of species of metals and supports on the hydrogenation activity of carbon-supported metal sulfides catalysts; Tanso biryushi tanji shokubai no suisoka kassei ni taisuru kassei kinzoku oyobi tantaishu no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Sakanishi, K.; Hasuo, H.; Taniguchi, H.; Nagamatsu, T.; Mochida, I. [Kyushu University, Fukuoka (Japan). Institute of Advanced Material Study

    1996-10-28

    In order to design catalysts suitable for primary liquefaction stage and secondary upgrading stage respectively in the multi-stage liquefaction process, various carbon-supported catalysts were prepared. Catalytic activities of them were investigated for the hydrogenation of 1-methylnaphthalene, to discuss the influences of metals and carbon species on the catalytic activity. Various water soluble and oil soluble Mo and Ni salts were used for NiMo supported catalysts. Among various carbon supports, Ketjen Black (KB) was effective for preparing the catalyst showing the most excellent hydrogenation activity. The KB and Black Pearl 2000 (BP2000) showing high hydrogenation activity were fine particles having high specific surface area more than 1000 m{sup 2}/g and primary particle diameter around 30 nm. This was inferred to contribute to the high dispersion support of active metals. Since such fine particles of carbon exhibited hydrophobic surface, they were suitable for preparing catalysts from the methanol-soluble metals. Although Ni and Mo added iron-based catalysts provided lower aromatic hydrogenation activity, they exhibited liquefaction activity competing with the NiMo/KB catalyst. 3 refs., 1 fig., 3 tabs.

  17. Non-noble metal based catalysts for aqueous phase processing

    NARCIS (Netherlands)

    van Haasterecht, T.|info:eu-repo/dai/nl/328206458

    2015-01-01

    This thesis concerns the evaluation of the potential of supported non-noble metal catalysts in aqueous phase processes for the production hydrogen and oxygenates. The aim of this thesis is to investigate how different factors, especially the nature of the metal, additives and reaction conditions,

  18. Single-catalyst high-weight% hydrogen storage in an N-heterocycle synthesized from lignin hydrogenolysis products and ammonia.

    Science.gov (United States)

    Forberg, Daniel; Schwob, Tobias; Zaheer, Muhammad; Friedrich, Martin; Miyajima, Nobuyoshi; Kempe, Rhett

    2016-10-20

    Large-scale energy storage and the utilization of biomass as a sustainable carbon source are global challenges of this century. The reversible storage of hydrogen covalently bound in chemical compounds is a particularly promising energy storage technology. For this, compounds that can be sustainably synthesized and that permit high-weight% hydrogen storage would be highly desirable. Herein, we report that catalytically modified lignin, an indigestible, abundantly available and hitherto barely used biomass, can be harnessed to reversibly store hydrogen. A novel reusable bimetallic catalyst has been developed, which is able to hydrogenate and dehydrogenate N-heterocycles most efficiently. Furthermore, a particular N-heterocycle has been identified that can be synthesized catalytically in one step from the main lignin hydrogenolysis product and ammonia, and in which the new bimetallic catalyst allows multiple cycles of high-weight% hydrogen storage.

  19. Hydrogen Production via Steam Reforming of Ethyl Alcohol over Palladium/Indium Oxide Catalyst

    Directory of Open Access Journals (Sweden)

    Tetsuo Umegaki

    2009-01-01

    Full Text Available We report the synergetic effect between palladium and indium oxide on hydrogen production in the steam reforming reaction of ethyl alcohol. The palladium/indium oxide catalyst shows higher hydrogen production rate than indium oxide and palladium. Palladium/indium oxide affords ketonization of ethyl alcohol with negligible by-product carbon monoxide, while indium oxide mainly affords dehydration of ethyl alcohol, and palladium affords decomposition of ethyl alcohol with large amount of by-product carbon monoxide. The catalytic feature of palladium/indium oxide can be ascribed to the formation of palladium-indium intermetallic component during the reaction as confirmed by X-ray diffraction and X-ray photoelectron spectroscopic measurements.

  20. Kinetics on NiZn Bimetallic Catalysts for Hydrogen Evolution via Selective Dehydrogenation of Methylcyclohexane to Toluene

    KAUST Repository

    Shaikh Ali, Anaam

    2017-01-18

    Liquid organic chemical hydrides are effective hydrogen storage media for easy and safe transport. The chemical couple of methylcyclohexane (MCH) and toluene (TOL) has been considered one of the feasible cycles for a hydrogen carrier, but the selective dehydrogenation of MCH to TOL has been reported using only Pt-based noble metal catalysts. This study reports MCH dehydrogenation to TOL using supported NiZn as a selective, non-noble-metal catalyst. A combined experimental and computational study was conducted to provide insight into the site requirements and reaction mechanism for MCH dehydrogenation to TOL, which were compared with those for cyclohexane (CH) dehydrogenation to benzene (BZ). The kinetic measurements carried out at 300-360°C showed an almost zero order with respect to MCH pressure in the high-pressure region (≥10 kPa) and nearly a positive half order with respective to H pressure (≤40 kPa). These kinetic data for the dehydrogenation reaction paradoxically indicate that hydrogenation of a strongly chemisorbed intermediate originating from TOL is the rate-determining step. Density functional theory (DFT) calculation confirms that the dehydrogenated TOL species at the aliphatic (methyl) position group (CHCH) were strongly adsorbed on the surface, which must be hydrogenated to desorb as TOL. This hydrogen-assisted desorption mechanism explains the essential role of excess H present in the feed in maintaining the activity of the metallic surface for hydrogenation. The rate of the CH to BZ reaction was less sensitive to H pressure than that of MCH to TOL, which can be explained by the absence of a methyl group in the structure, which in turn reduces the binding energy of the adsorbed species. DFT suggests that the improved TOL selectivity by adding Zn to Ni was due to Zn atoms preferentially occupying low-coordination sites on the surface (the corner and edge sites), which are likely the unselective sites responsible for the C-C dissociation of the

  1. Hydrogenation of 1-hexene in benzene on modified Pt/Al/sub 2/O/sub 3/ catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Maryshev, V.B.; Grishchenko, A.V.; Zharkov, B.B.; Polyakov, A.A.; Fedorov, V.S.

    Studies were conducted on the regulation of the selectivity of Pt/Al/sub 2/O/sub 3/ catalysts in the hydrogenation of 1-hexene in benzene by the addition of a second metal (Cd, Cu, Pb, Sn) to create bimetallic catalysts. Analysis of the catalytic efficiencies at 180/sup 0/C under 1.5 MPa hydrogen with a 1-hexene:benzene:octane ratio of 1:2:2 demonstrated that addition of a second metal depressed the activity of the catalyst in the hydrogenation of 1-hexene. However, selectivity in the hydrogenation of the olefin increased, indicating that hydrogenation of the aromatic hydrocarbon was inhibited to a greater extent. Cadmium was most effective in promoting selective hydrogenation of 1-hexene. In the Pt-Cd system the reaction was first order in 1-hexene and zero order in benzene. The introduction of 0.2 atoms of Cd per one atom of Pt was sufficient to decrease benzene hydrogenation 2-fold. Analysis of adsorption data showed that increased selectivity of 1-hexene hydrogenation was due to a four-fold decrease in benzene adsorption to the catalytic surface as a result of Cd addition. 5 references, 2 figures.

  2. Bioinspired molecular co-catalysts bonded to a silicon photocathode for solar hydrogen evolution

    DEFF Research Database (Denmark)

    Hou, Yidong; Abrams, Billie L.; Vesborg, Peter Christian Kjærgaard

    2011-01-01

    -abundant alternatives are needed for large-scale use. We show that bioinspired molecular clusters based on molybdenum and sulphur evolve hydrogen at rates comparable to that of platinum. The incomplete cubane-like clusters (Mo3S 4) efficiently catalyse the evolution of hydrogen when coupled to a p-type Si semiconductor...... that harvests red photons in the solar spectrum. The current densities at the reversible potential match the requirement of a photoelectrochemical hydrogen production system with a solar-to-hydrogen efficiency in excess of 10% (ref. 16). The experimental observations are supported by density functional theory...

  3. Cuboid Ni2P as a Bifunctional Catalyst for Efficient Hydrogen Generation from Hydrolysis of Ammonia Borane and Electrocatalytic Hydrogen Evolution.

    Science.gov (United States)

    Du, Yeshuang; Liu, Chao; Cheng, Gongzhen; Luo, Wei

    2017-11-16

    The design of high-performance catalysts for hydrogen generation is highly desirable for the upcoming hydrogen economy. Herein, we report the colloidal synthesis of nanocuboid Ni 2 P by the thermal decomposition of nickel chloride hexahydrate (NiCl 2 ⋅6 H 2 O) and trioctylphosphine. The obtained nanocuboid Ni 2 P was characterized by using powder X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and inductively coupled plasma atomic emission spectroscopy. For the first time, the as-synthesized nanocuboid Ni 2 P is used as a bifunctional catalyst for hydrogen generation from the hydrolysis of ammonia borane and electrocatalytic hydrogen evolution. Owing to the strong synergistic electronic effect between Ni and P, the as-synthesized Ni 2 P exhibits catalytic performance that is superior to its counterpart without P doping. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Hydrodeoxygenation of phenol over Pd catalysts by in-situ generated hydrogen from aqueous reforming of formic acid

    DEFF Research Database (Denmark)

    Zeng, Ying; Wang, Ze; Lin, Weigang

    2016-01-01

    Hydrodeoxygenation of phenol, as model compound of bio-oil, was investigated over Pd catalysts, using formic acid as a hydrogen donor. The order of activity for deoxygenation of phenol with Pd catalysts was found to be: Pd/SiO2 > Pd/MCM-41 > Pd/CA > Pd/Al2O3 > Pd/HY approximate to Pd/ZrO2 ≈ Pd...

  5. Selective hydrogenation of citral over supported Pt catalysts: insight into support effects

    Science.gov (United States)

    Wang, Xiaofeng; Hu, Weiming; Deng, Baolin; Liang, Xinhua

    2017-04-01

    Highly dispersed platinum (Pt) nanoparticles (NPs) were deposited on various substrates by atomic layer deposition (ALD) in a fluidized bed reactor at 300 °C. The substrates included multi-walled carbon nanotubes (MWCNTs), silica gel (SiO2), commercial γ-Al2O3, and ALD-prepared porous Al2O3 particles (ALD-Al2O3). The results of TEM analysis showed that 1.3 nm Pt NPs were highly dispersed on all different supports. All catalysts were used for the reaction of selective hydrogenation of citral to unsaturated alcohols (UA), geraniol, and nerol. Both the structure and acidity of supports affected the activity and selectivity of Pt catalysts. Pt/SiO2 showed the highest activity due to the strong acidity of SiO2 and the conversion of citral reached 82% after 12 h with a selectivity of 58% of UA. Pt/MWCNTs showed the highest selectivity of UA, which reached 65% with a conversion of 38% due to its unique structure and electronic effect. The cycling experiments indicated that Pt/MWCNTs and Pt/ALD-Al2O3 catalysts were more stable than Pt/SiO2, as a result of the different interactions between the Pt NPs and the supports.

  6. Superefficient thin film multilayer catalyst for generating hydrogen from sodium borohydride

    Science.gov (United States)

    Hu, Lunghao; Ceccato, R.; Raj, R.

    A multilayer catalyst consisting of a electrophoretically deposited thin film of carbon nanotubes (CNTs) on a substrate of carbon fibers, followed by a coating of polymer-derived silicon carbonitride (SiCN), which is then decorated with a monolayer of transition metals is shown to perform at the upperbound of the phenomemological prediction from an earlier work [1]. A figure-of-merit for first order kinetics is equal to 4600 L min -1 [NaBH 4] -1 g met -1, which is nearly 30 times the value reported in literature, is achieved. This high FOM is attributed to the CNT-thin film, as opposed to the thick CNT-paper used in previous work, thus needing merely 0.15 wt% quantities of precious metals for effective catalysis. This new architecture corroborates the concepts that: (i) the catalytic activity derives mainly from the surface of the CNT substrate, and (ii) the silicon carbonitride interlayer is instrumental in dispersing the transition metals into a monolayer. The hydrogen generation rate (HGR) for zero order kinetics, which is obtained when [NaBH 4] > 0.03 M, is measured to be 75 L min -1 g met -1, which is among the higher values reported in the literature. The present multilayer catalysts are able to perform without fading for many cycles, presumably because the bondings in the substrate are predominantly covalent. This feature adds further uniqueness to this multilayer catalyst.

  7. Antifouling character of 'active' hybrid xerogel coatings with sequestered catalysts for the activation of hydrogen peroxide.

    Science.gov (United States)

    McMaster, Danielle M; Bennett, Stephanie M; Tang, Ying; Finlay, John A; Kowalke, Gregory L; Nedved, Brian; Bright, Frank V; Callow, Maureen E; Callow, James A; Wendt, Dean E; Hadfield, Michael G; Detty, Michael R

    2009-01-01

    Halide-permeable xerogel films prepared from sols containing 50 mol% aminopropyltriethoxysilane (APTES)/50 mol% tetraethoxysilane (TEOS) or 10 mol% APTES/90 mol% TEOS and 0.015 M selenoxide or telluride catalyst in the sol gave reduced settlement of cypris larvae of the barnacle Balanus amphitrite and larvae of the tubeworm Hydroides elegans in the presence of artificial seawater (ASW) and hydrogen peroxide (5-100 microM) relative to glass controls. Settlement of Ulva zoospores was lower on both the 50 mol% APTES/50 mol% TEOS and 10 mol% APTES/90 mol% TEOS xerogel formulations in comparison with glass controls with or without the added catalyst. The 50 mol% APTES/50 mol%TEOS xerogel containing telluride catalyst gave reduced settlement of Ulva zoospores in the presence of 100 microM H(2)O(2) in ASW compared with the same coating without added peroxide. Scanning electron microscopy and XPS data suggest that exposure to H(2)O(2) does not lead to chemical or morphological changes on the xerogel surface.

  8. Selective hydrogenation of citral over supported Pt catalysts: insight into support effects

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaofeng [Missouri University of Science and Technology, Department of Chemical and Biochemical Engineering (United States); Hu, Weiming; Deng, Baolin [University of Missouri, Department of Civil and Environmental Engineering (United States); Liang, Xinhua, E-mail: liangxin@mst.edu [Missouri University of Science and Technology, Department of Chemical and Biochemical Engineering (United States)

    2017-04-15

    Highly dispersed platinum (Pt) nanoparticles (NPs) were deposited on various substrates by atomic layer deposition (ALD) in a fluidized bed reactor at 300 °C. The substrates included multi-walled carbon nanotubes (MWCNTs), silica gel (SiO{sub 2}), commercial γ-Al{sub 2}O{sub 3}, and ALD-prepared porous Al{sub 2}O{sub 3} particles (ALD-Al{sub 2}O{sub 3}). The results of TEM analysis showed that ~1.3 nm Pt NPs were highly dispersed on all different supports. All catalysts were used for the reaction of selective hydrogenation of citral to unsaturated alcohols (UA), geraniol, and nerol. Both the structure and acidity of supports affected the activity and selectivity of Pt catalysts. Pt/SiO{sub 2} showed the highest activity due to the strong acidity of SiO{sub 2} and the conversion of citral reached 82% after 12 h with a selectivity of 58% of UA. Pt/MWCNTs showed the highest selectivity of UA, which reached 65% with a conversion of 38% due to its unique structure and electronic effect. The cycling experiments indicated that Pt/MWCNTs and Pt/ALD-Al{sub 2}O{sub 3} catalysts were more stable than Pt/SiO{sub 2}, as a result of the different interactions between the Pt NPs and the supports.

  9. Durable Cu composite catalyst for hydrogen production by high temperature methanol steam reforming

    Science.gov (United States)

    Matsumura, Yasuyuki

    2014-12-01

    Durable catalysts are necessitated for the high temperature methanol steam reforming in compact hydrogen processors. The high durability at 400 °C can be obtained with a composite Cu catalyst where a small amount of Cu-ZnO-ZrO2-Y2O3-In2O3 is coprecipitated on a zirconia support. The lifetime of the composite catalyst containing 3 wt.% Cu is estimated to be as long as 53 × 102 h at 400 °C to produce the full conversion at a contact time of 250 g h m-3. The deactivation rate empirically relates to the cube of the activity. The gradual deactivation is caused by the gradual reduction of the Cu surface amount and also by the reduction of the surface activity which is believed to decrease with an increase in the Cu particle size. The interaction between the thin layer of the coprecipitate and the support surface probably suppresses the aggregation of the coprecipitate leading to Cu sintering.

  10. Hydrogen production with nickel powder cathode catalysts in microbial electrolysis cells

    KAUST Repository

    Selembo, Priscilla A.

    2010-01-01

    Although platinum is commonly used as catalyst on the cathode in microbial electrolysis cells (MEC), non-precious metal alternatives are needed to reduce costs. Cathodes were constructed using a nickel powder (0.5-1 μm) and their performance was compared to conventional electrodes containing Pt (0.002 μm) in MECs and electrochemical tests. The MEC performance in terms of coulombic efficiency, cathodic, hydrogen and energy recoveries were similar using Ni or Pt cathodes, although the maximum hydrogen production rate (Q) was slightly lower for Ni (Q = 1.2-1.3 m3 H2/m3/d; 0.6 V applied) than Pt (1.6 m3 H2/m3/d). Nickel dissolution was minimized by replacing medium in the reactor under anoxic conditions. The stability of the Ni particles was confirmed by examining the cathodes after 12 MEC cycles using scanning electron microscopy and linear sweep voltammetry. Analysis of the anodic communities in these reactors revealed dominant populations of Geobacter sulfurreduces and Pelobacter propionicus. These results demonstrate that nickel powder can be used as a viable alternative to Pt in MECs, allowing large scale production of cathodes with similar performance to systems that use precious metal catalysts. © 2009 Professor T. Nejat Veziroglu.

  11. Nitrogen-doped fullerene as a potential catalyst for hydrogen fuel cells.

    Science.gov (United States)

    Gao, Feng; Zhao, Guang-Lin; Yang, Shizhong; Spivey, James J

    2013-03-06

    We examine the possibility of nitrogen-doped C60 fullerene (N-C60) as a cathode catalyst for hydrogen fuel cells. We use first-principles spin-polarized density functional theory calculations to simulate the electrocatalytic reactions on N-C60. The first-principles results show that an O2 molecule can be adsorbed and partially reduced on the N-C complex sites (Pauling sites) of N-C60 without any activation barrier. Through a direct pathway, the partially reduced O2 can further react with H(+) and additional electrons and complete the water formation reaction (WFR) with no activation energy barrier. In the indirect pathway, reduced O2 reacts with H(+) and additional electrons to form H2O molecules through a transition state (TS) with a small activation barrier (0.22-0.37 eV). From an intermediate state to a TS, H(+) can obtain a kinetic energy of ∼0.95-3.68 eV, due to the Coulomb electric interaction, and easily overcome the activation energy barrier during the WFR. The full catalytic reaction cycles can be completed energetically, and N-C60 fullerene recovers to its original structure for the next catalytic reaction cycle. N-C60 fullerene is a potential cathode catalyst for hydrogen fuel cells.

  12. Designing supported palladium-on-gold bimetallic nano-catalysts for controlled hydrogenation of acetylene in large excess of ethylene

    Science.gov (United States)

    Malla, Pavani

    Ethylene is used as a starting point for many chemical intermediates in the petrochemical industry. It is predominantly produced through steam cracking of higher hydrocarbons (ethane, propane, butane, naphtha, and gas oil). During the cracking process, a small amount of acetylene is produced as a side product. However, acetylene must be removed since it acts as a poison for ethylene polymerization catalysts at even ppm concentrations (>5 ppm). Thus, the selective hydrogenation of acetylene to ethylene is an important process for the purification of ethylene. Conventional, low weight loading Pd catalysts are used for this selective reaction in high concentration ethylene streams. Gold was initially considered to be catalytically inactive for a long time. This changed when gold was seen in the context of the nanometric scale, which has indeed shown it to have excellent catalytic activity as a homogeneous or a heterogeneous catalyst. Gold is proved to have high selectivity to ethylene but poor at conversion. Bimetallic Au and Pd catalysts have exhibited superior activity as compared to Pd particles in semi-hydrogenation. Hydrogenation of acetylene was tested using this bimetallic combination. The Pd-on-Au bimetallic catalyst structure provides a new synthesis approach in improving the catalytic properties of monometallic Pd materials. TiO 2 as a support material and 0.05%Pd loading on 1%Au on titania support and used different treatment methods like washing plasma and reduction between the two metal loadings and was observed under 2:1 ratio. In my study there were two set of catalysts which were prepared by a modified incipient wetness impregnation technique. Out of all the reaction condition the catalyst which was reduced after impregnating gold and then impregnating palladium which was further treated in non-thermal hydrogen plasma and then pretreated in hydrogen till 250°C for 1 hour produced the best activity of 76% yield at 225°C. Stability tests were conducted

  13. Use of Hydrogen Chemisorption and Ethylene Hydrogenation as Predictors for Aqueous Phase Reforming of Lactose over Ni@Pt and Co@Pt Bimetallic Overlayer Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Qinghua; Skoglund, Michael D.; Zhang, Chen; Morris, Allen R.; Holles, Joseph H.

    2016-10-20

    Overlayer Pt on Ni (Ni@Pt) or Co (Co@Pt) were synthesized and tested for H2 generation from APR of lactose. H2 chemisorption descriptor showed that Ni@Pt and Co@Pt overlayer catalysts had reduced H2 adsorption strength compared to a Pt only catalyst, which agree with computational predictions. The overlayer catalysts also demonstrated lower activity for ethylene hydrogenation than the Pt only catalyst, which likely resulted from decreased H2 binding strength decreasing the surface coverage of H2. XAS results showed that overlayer catalysts exhibited higher white line intensity than the Pt catalyst, which indicates a negative d-band shift for the Pt overlayer, further providing evidence for overlayer formation. Lactose APR studies showed that lactose can be used as feedstock to produce H2 and CO under desirable reaction conditions. The Pt active sites of Ni@Pt and Co@Pt overlayer catalysts showed significantly enhanced H2 production selectivity and activity when compared with that of a Pt only catalyst. The single deposition overlayer with the largest d-band shift showed the highest H2 activity. The results suggest that overlayer formation using directed deposition technique could modify the behavior of the surface metal and ultimately modify the APR activity.

  14. Mechanism-Based Design of Green Oxidation Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Rybak-Akimova, Elena [Tufts Univ., Medford, MA (United States)

    2015-03-16

    situation. Growing families of synthetic iron complexes that resemble active sites of metalloenzymes produce metal-based intermediates (rather than hydroxyl radicals) in reactions with oxygen donors. These complexes are very promising for selective oxygen and peroxide activation. In order to understand the mechanisms of metal-based small molecule activation, kinetically competent metal-oxygen intermediates must be identified. One of the grand challenges identified by the Department of Energy workshop "Catalysis for Energy" is understanding mechanisms and dynamics of catalyzed reactions. The research summarized herein focuses on detailed characterization of the formation and reactivity of various iron-peroxo- and iron-oxo intermediates that are involved in catalysis. Rates of rapid reactions were studied at low temperatures by a specialized technique termed cryogenic stopped-flow spectrophotometry. These measurements identified reaction conditions which favor the formation of catalytically competent oxidants. Chemical structures of reactive complexes was determined, and new, efficient catalysts for hydrocarbon oxidation were synthesized. Importantly, these catalysts are selective, they promote oxidation of hydrocarbons at a specific site. The catalysts are also efficient and robust, hundreds of cycles of substrate oxidation occur within minutes at room temperature. Furthermore, they enable utilization of environmentally friendly oxidants, such as hydrogen peroxide, which produces water as the only byproduct. Mechanistic insights uncovered the role of various acid-containing additives in catalytic oxidations. Proton delivery to the active catalytic sites facilitated oxidations, similarly to the catalytic pathways in metal-containing enzymes. Under certain conditions, two metals in one complex can act in concert, modeling the reactivity of a bacterial enzyme which converts methane into methanol. In related studies, a family of nickel complexes that react with carbon dioxide at

  15. Sieving hydrogen based on its high compressibility

    Science.gov (United States)

    Chen, Hangyan; Sun, Deyan; Gong, Xingao; Liu, Zhifeng

    2011-03-01

    Based on carbon nanotube intramolecular junction and a C60, a molecular sieve for hydrogen is presented. The small interspace between C60 and junction provides a size changeable channel for the permselectivity of hydrogen while blocking Ne and Ar. The sieving mechanism is due to the high compressibility of hydrogen.

  16. Role of the support in the formation of the active phase of catalysts for the hydrogenation of carbon monoxide

    Energy Technology Data Exchange (ETDEWEB)

    Kamalov, G.K.; Povolotskii, E.Yu.; Silant`eva, O.A. [A.V. Bogatskii Institute of Physical Chemistry, Odessa (Ukraine)] [and others

    1992-03-01

    A series of supports, i.e., substitutional solid solutions of metal oxides in an Al{sub 2}O{sub 3} matrix, which can be used to prepare Co and Ni-containing catalysts for the hydrogenation of carbon monoxide, has been obtained. It has been shown that the activity of the catalysts correlates closely with the donor-acceptor properties of the supports and that the character of the laws discovered in largely determined by the extent of reduction of the active phase of the catalysts. 20 refs., 7 figs., 1 tab.

  17. Influence of physicochemical treatments on iron-based spent catalyst for catalytic oxidation of toluene.

    Science.gov (United States)

    Kim, Sang Chai; Shim, Wang Geun

    2008-06-15

    The catalytic oxidation of toluene was studied over an iron-based spent and regenerated catalysts. Air, hydrogen, or four different acid solutions (oxalic acid (C2H2O4), citric acid (C6H8O7), acetic acid (CH3COOH), and nitric acid (HNO3)) were employed to regenerate the spent catalyst. The properties of pretreated spent catalyst were characterized by the Brunauer Emmett Teller (BET), inductively coupled plasma (ICP), temperature programmed reduction (TPR), and X-ray diffraction (XRD) analyses. The air pretreatment significantly enhanced the catalytic activity of the spent catalyst in the pretreatment temperature range of 200-400 degrees C, but its catalytic activity diminished at the pretreatment temperature of 600 degrees C. The catalytic activity sequence with respect to the air pretreatment temperatures was 400 degrees C>200 degrees C>parent>600 degrees C. The TPR results indicated that the catalytic activity was correlated with both the oxygen mobility and the amount of available oxygen on the catalyst. In contrast, the hydrogen pretreatment had a negative effect on the catalytic activity, and toluene conversion decreased with increasing pretreatment temperatures (200-600 degrees C). The XRD and TPR results confirmed the formation of metallic iron which had a negative effect on the catalytic activity with increasing pretreatment temperature. The acid pretreatment improved the catalytic activity of the spent catalyst. The catalytic activity sequence with respect to different acids pretreatment was found to be oxalic acid>citric acid>acetic acid>or=nitric acid>parent. The TPR results of acid pretreated samples showed an increased amount of available oxygen which gave a positive effect on the catalytic activity. Accordingly, air or acid pretreatments were more promising methods of regenerating the iron-based spent catalyst. In particular, the oxalic acid pretreatment was found to be most effective in the formation of FeC2O4 species which contributed highly to the

  18. Highly efficient bimetal synergetic catalysis by a multi-wall carbon nanotube supported palladium and nickel catalyst for the hydrogen storage of magnesium hydride.

    Science.gov (United States)

    Yuan, Jianguang; Zhu, Yunfeng; Li, Liquan

    2014-06-25

    A multi-wall carbon nanotube supported Pd and Ni catalyst efficiently catalyzes the hydrogen storage of magnesium hydride prepared by HCS + MM. Excellent hydrogen storage properties were obtained: hydrogen absorption - 6.44 wt% within 100 s at 373 K, hydrogen desorption - 6.41 wt% within 1800 s at 523 K and 6.70 wt% within 400 s at 573 K.

  19. An Efficient Pd-Sn Catalyst Supported on MWNTs for Hydrogenation of High Concentrated Acetylene Feedstocks: The Potential Role of Isolated Adsorption Site

    Directory of Open Access Journals (Sweden)

    E. Esmaeili

    2014-04-01

    Full Text Available In the present study, tin-promoted Pd/MWNTs nanocatalystwas synthesized via polyol technique for application in hydrogenation of high-concentrated acetylene feedstocks. TEM images showed a restricted distribution of nanoparticles in the range of 3-5 nm. The results indicated that nanoparticles sizes were resistant to further catalyst deactivation. XRD patterns signified alloying between Pd and Sn which contained a high percentage of ordered intermetallic structures (70.8%, as confirmed by XPS. According to the results, pore blocking and/or fouling was known as the main reasons of the catalyst deactivation. Here, we supposed a novel deactivation mechanism based on which dehydrogenation susceptibility of carbonaceous species (green oil played a significant role in the formation of the isolated adsorption sites and then, catalyst deactivation.

  20. Hydrogen production by auto-thermal reforming of ethanol over nickel catalyst supported on metal oxide-stabilized zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Youn, Min Hye; Seo, Jeong Gil; Song, In Kyu [School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Shinlim-dong, Kwanak-ku, Seoul 151-744 (Korea)

    2010-04-15

    Metal oxide-stabilized mesoporous zirconia supports (M-ZrO{sub 2}) with different metal oxide stabilizer (M = Zr, Y, La, Ca, and Mg) were prepared by a templating sol-gel method. 20 wt% Ni catalysts supported on M-ZrO{sub 2} (M = Zr, Y, La, Ca, and Mg) were then prepared by an incipient wetness impregnation method for use in hydrogen production by auto-thermal reforming of ethanol. The effect of metal oxide stabilizer (M = Zr, Y, La, Ca, and Mg) on the catalytic performance of supported nickel catalysts was investigated. Ni/M-ZrO{sub 2} (M = Y, La, Ca, and Mg) catalysts exhibited a higher catalytic performance than Ni/Zr-ZrO{sub 2}, because surface oxygen vacancy of M-ZrO{sub 2} (M = Y, La, Ca, and Mg) and reducibility of Ni/M-ZrO{sub 2} (M = Y, La, Ca, and Mg) were enhanced by the addition of lower valent metal cation. Hydrogen yield over Ni/M-ZrO{sub 2} (M = Zr, Y, La, Ca, and Mg) catalyst was monotonically increased with increasing both surface oxygen vacancy of M-ZrO{sub 2} support and reducibility of Ni/M-ZrO{sub 2} catalyst. Among the catalysts tested, Ni catalyst supported on yttria-stabilized mesoporous zirconia (Ni/Y-ZrO{sub 2}) showed the best catalytic performance. (author)

  1. Hydro-isomerization of n-hexane on bi-functional catalyst: Effect of total and hydrogen partial pressures

    Science.gov (United States)

    Thoa, Dao Thi Kim; Loc, Luu Cam

    2017-09-01

    The effect of both total pressure and hydrogen partial pressure during n-hexane hydro-isomerization over platinum impregnated on HZSM-5 was studied. n-Hexane hydro-isomerization was conducted at atmospheric pressure and 0.7 MPa to observe the influence of total pressure. In order to see the effect of hydrogen partial pressure, the reaction was taken place at different partial pressure of hydrogen varied from 307 hPa to 718 hPa by dilution with nitrogen to keep the total pressure at 0.1 MPa. Physico-chemical characteristics of catalyst were determined by the methods of nitrogen physi-sorption BET, SEM, XRD, TEM, NH3-TPD, TPR, and Hydrogen Pulse Chemi-sorption. Activity of catalyst in the hydro-isomerization of n-hexane was studied in a micro-flow reactor in the temperature range of 225-325 °C; the molar ratio H2/ hydrocarbon: 5.92, concentration of n-hexane: 9.2 mol.%, GHSV 2698 h-1. The obtained catalyst expressed high acid density, good reducing property, high metal dispersion, and good balance between metallic and acidic sites. It is excellent contact for n-hexane hydro-isomerization. At 250 °C, n-hexane conversion and selectivity were as high as 59-76 % and 85-99 %, respectively. It was found that catalytic activity was promoted either by total pressure or hydrogen partial pressure. At total pressure of 0.7 MPa while hydrogen partial pressure of 718 hPa, catalyst produced 63 RON liquid product containing friendly environmental iso-paraffins which is superior blending stock for green gasoline. Hydrogen did not only preserve catalyst actives by depressing hydrocracking and removing coke precursors but also facilitated hydride transfer step in the bi-functional bi-molecular mechanism.

  2. Catalytic activity of mono and bimetallic Zn/Cu/MWCNTs catalysts for the thermocatalyzed conversion of methane to hydrogen

    Science.gov (United States)

    Erdelyi, B.; Oriňak, A.; Oriňaková, R.; Lorinčík, J.; Jerigová, M.; Velič, D.; Mičušík, M.; Omastová, M.; Smith, R. M.; Girman, V.

    2017-02-01

    Mono and bimetallic multiwalled carbon nanotubes (MWCNTs) fortified with Cu and Zn metal particles were studied to improve the efficiency of the thermocatalytic conversion of methane to hydrogen. The surface of the catalyst and the dispersion of the metal particles were studied by scanning electron microscopy (SEM), secondary ion mass spectrometry (SIMS) and with energy-dispersive X-ray spectroscopy (EDS). It was confirmed that the metal particles were successfully dispersed on the MWCNT surface and XPS analysis showed that the Zn was oxidised to ZnO at high temperatures. The conversion of methane to hydrogen during the catalytic pyrolysis was studied by pyrolysis gas chromatography using different amounts of catalyst. The best yields of hydrogen were obtained using pyrolysis conditions of 900 °C and 1.2 mg of Zn/Cu/MWCNT catalyst for 1.5 mL of methane.The initial conversion of methane to hydrogen obtained with Zn/Cu/MWCNTs was 49%, which represent a good conversion rate of methane to hydrogen for a non-noble metal catalyst.

  3. Hydrogen cold plasma for synthesizing Pd/C catalysts: the effect of support–metal ion interaction

    Science.gov (United States)

    Zhuang, LI; Xiuling, ZHANG; Yuzhuo, ZHANG; Dongzhi, DUAN; Lanbo, DI

    2018-01-01

    It has been found that cold plasma is a facile and environmentally benign method for synthesizing supported metal catalysts, and great efforts have been devoted to enlarging its applications. However, little work has been done to disclose the influence mechanism, which is significant for controllable synthesis. In this work, hydrogen cold plasma was adopted to synthesize a palladium catalyst supported on activated carbon (Pd/C-P) using H2PdCl4 as a Pd precursor followed by calcination in hydrogen gas to remove the chlorine ions. The Pd/C-P catalyst was found to be made of larger Pd nanoparticles showing a decreased migration to the support outer surface than that prepared by the conventional thermal hydrogen reduction method (Pd/C-C). Meanwhile, the pore diameter of the activated carbon support is small (∼4 nm). Therefore, Pd/C-P exhibits lower CO oxidation activity than Pd/C-C. It was proposed that the strong interaction between the activated carbon and {{{{PdCl}}}4}2-, and the enhanced metal–support interaction caused by hydrogen cold plasma reduction made it difficult for Pd nanoparticles to migrate to the support outer surface. The larger-sized Pd nanoparticles for Pd/C-P may be due to the Coulomb interaction resulting in the disturbance of the metal–support interaction. This work has important guiding significance for the controllable synthesis of supported metal catalysts by hydrogen cold plasma.

  4. Metal-polypyridyl catalysts for electro- and photochemical reduction of water to hydrogen.

    Science.gov (United States)

    Zee, David Z; Chantarojsiri, Teera; Long, Jeffrey R; Chang, Christopher J

    2015-07-21

    Climate change, rising global energy demand, and energy security concerns motivate research into alternative, sustainable energy sources. In principle, solar energy can meet the world's energy needs, but the intermittent nature of solar illumination means that it is temporally and spatially separated from its consumption. Developing systems that promote solar-to-fuel conversion, such as via reduction of protons to hydrogen, could bridge this production-consumption gap, but this effort requires invention of catalysts that are cheap, robust, and efficient and that use earth-abundant elements. In this context, catalysts that utilize water as both an earth-abundant, environmentally benign substrate and a solvent for proton reduction are highly desirable. This Account summarizes our studies of molecular metal-polypyridyl catalysts for electrochemical and photochemical reduction of protons to hydrogen. Inspired by concept transfer from biological and materials catalysts, these scaffolds are remarkably resistant to decomposition in water, with fast and selective electrocatalytic and photocatalytic conversions that are sustainable for several days. Their modular nature offers a broad range of opportunities for tuning reactivity by molecular design, including altering ancillary ligand electronics, denticity, and/or incorporating redox-active elements. Our first-generation complex, [(PY4)Co(CH3CN)2](2+), catalyzes the reduction of protons from a strong organic acid to hydrogen in 50% water. Subsequent investigations with the pentapyridyl ligand PY5Me2 furnished molybdenum and cobalt complexes capable of catalyzing the reduction of water in fully aqueous electrolyte with 100% Faradaic efficiency. Of particular note, the complex [(PY5Me2)MoO](2+) possesses extremely high activity and durability in neutral water, with turnover frequencies at least 8500 mol of H2 per mole of catalyst per hour and turnover numbers over 600 000 mol of H2 per mole of catalyst over 3 days at an

  5. An Alumina-Supported Ni-La-Based Catalyst for Producing Synthetic Natural Gas

    Directory of Open Access Journals (Sweden)

    Daniel E. Rivero-Mendoza

    2016-10-01

    Full Text Available LaNi5, known for its hydrogen storage capability, was adapted to the form of a metal oxide-supported (γ-Al2O3 catalyst and its performance for the Sabatier reaction assessed. The 20 wt % La-Ni/γ-Al2O3 particles were prepared via solution combustion synthesis (SCS and exhibited good catalytic activity, achieving a CO2 conversion of 75% with a high CH4 selectivity (98% at 1 atm and 300 °C. Characteristics of the La-Ni/γ-Al2O3 catalyst were identified at various stages of the catalytic process (as-prepared, activated, and post-reaction and in-situ DRIFTS was used to probe the reaction mechanism. The as-prepared catalyst contained amorphous surface La–Ni spinels with particle sizes <6 nm. The reduction process altered the catalyst make-up where, despite the reducing conditions, Ni2+-based particles with diameters between 4 and 20 nm decorated with LaOx moieties were produced. However, the post-reaction catalyst had particle sizes of 4–9 nm and comprised metallic Ni, with the LaOx decoration reverting to a form akin to the as-prepared catalyst. DRIFTS analysis indicated that formates and adsorbed CO species were present on the catalyst surface during the reaction, implying the reaction proceeded via a H2-assisted and sequential CO2 dissociation to C and O. These were then rapidly hydrogenated into CH4 and H2O.

  6. Discovery of technical methanation catalysts based on computational screening

    DEFF Research Database (Denmark)

    Sehested, Jens; Larsen, Kasper Emil; Kustov, Arkadii

    2007-01-01

    Methanation is a classical reaction in heterogeneous catalysis and significant effort has been put into improving the industrially preferred nickel-based catalysts. Recently, a computational screening study showed that nickel-iron alloys should be more active than the pure nickel catalyst and at ...

  7. Control in the Rate-Determining Step Provides a Promising Strategy To Develop New Catalysts for CO2 Hydrogenation: A Local Pair Natural Orbital Coupled Cluster Theory Study.

    Science.gov (United States)

    Mondal, Bhaskar; Neese, Frank; Ye, Shengfa

    2015-08-03

    The development of efficient catalysts with base metals for CO2 hydrogenation has always been a major thrust of interest. A series of experimental and theoretical work has revealed that the catalytic cycle typically involves two key steps, namely, base-promoted heterolytic H2 splitting and hydride transfer to CO2, either of which can be the rate-determining step (RDS) of the entire reaction. To explore the determining factor for the nature of RDS, we present herein a comparative mechanistic investigation on CO2 hydrogenation mediated by [M(H)(η(2)-H2)(PP3(Ph))](n+) (M = Fe(II), Ru(II), and Co(III); PP3(Ph) = tris(2-(diphenylphosphino)phenyl)phosphine) type complexes. In order to construct reliable free energy profiles, we used highly correlated wave function based ab initio methods of the coupled cluster type alongside the standard density functional theory. Our calculations demonstrate that the hydricity of the metal-hydride intermediate generated by H2 splitting dictates the nature of the RDS for the Fe(II) and Co(III) systems, while the RDS for the Ru(II) catalyst appears to be ambiguous. CO2 hydrogenation catalyzed by the Fe(II) complex that possesses moderate hydricity traverses an H2-splitting RDS, whereas the RDS for the high-hydricity Co(III) species is found to be the hydride transfer. Thus, our findings suggest that hydricity can be used as a practical guide in future catalyst design. Enhancing the electron-accepting ability of low-hydricity catalysts is likely to improve their catalytic performance, while increasing the electron-donating ability of high-hydricity complexes may speed up CO2 conversion. Moreover, we also established the active roles of base NEt3 in directing the heterolytic H2 splitting and assisting product release through the formation of an acid-base complex.

  8. Performance of Ru/La2O3–ZnO Catalyst for the Selective Hydrogenation of Benzene to Cyclohexene

    Directory of Open Access Journals (Sweden)

    Hendrik Spod

    2015-10-01

    Full Text Available Cyclohexene is an important intermediate product for a highly efficient and greener formation of major end products like adipic acid, nylon 6, and nylon 6.6. By using a complex tetra-phase system (g/l/l/s including hydrogen (g, water (l, an organic phase, i.e., benzene (l, and a supported ruthenium catalyst (s it is possible to get the desired intermediate cyclohexene based on benzene. We prepared an oxide-supported ruthenium catalyst that was applied together with minimal amounts of the additive NaDCA (sodium dicyanamide in a batch and continuous apparatus for the selective benzene hydrogenation. We compared these two processes and reached by an optimization of the reaction parameters in continuous process selectivities up to 50% at conversions of 36%. This corresponds to cyclohexene yields of 18% over a period of 100 h. Finally, the catalyst was characterized using X-ray diffraction (XRD, transmission electron spectroscopy (TEM, inductively coupled plasma optical emission spectrometry (ICP-OES, and laser scattering to understand the performance of the catalyst and the effect of the small deactivation.

  9. Attrition Resistant Fischer-Tropsch Catalysts Based on FCC Supports

    Energy Technology Data Exchange (ETDEWEB)

    Adeyiga, Adeyinka

    2010-02-05

    Commercial spent fluid catalytic cracking (FCC) catalysts provided by Engelhard and Albemarle were used as supports for Fe-based catalysts with the goal of improving the attrition resistance of typical F-T catalysts. Catalysts with the Ruhrchemie composition (100 Fe/5 Cu/4.2 K/25 spent FCC on mass basis) were prepared by wet impregnation. XRD and XANES analysis showed the presence of Fe{sub 2}O{sub 3} in calcined catalysts. FeC{sub x} and Fe{sub 3}O{sub 4} were present in the activated catalysts. The metal composition of the catalysts was analyzed by ICP-MS. F-T activity of the catalysts activated in situ in CO at the same conditions as used prior to the attrition tests was measured using a fixed bed reactor at T = 573 K, P = 1.38 MPa and H{sub 2}:CO ratio of 0.67. Cu and K promoted Fe supported over Engelhard provided spent FCC catalyst shows relatively good attrition resistance (8.2 wt% fines lost), high CO conversion (81%) and C{sub 5}+ hydrocarbons selectivity (18.3%).

  10. CuCo2O4 nanoplate film as a low-cost, highly active and durable catalyst towards the hydrolytic dehydrogenation of ammonia borane for hydrogen production

    Science.gov (United States)

    Liu, Quanbing; Zhang, Shengjie; Liao, Jinyun; Feng, Kejun; Zheng, Yuying; Pollet, Bruno G.; Li, Hao

    2017-07-01

    Catalytic dehydrogenation of ammonia borane is one of the most promising routes for the production of clean hydrogen as it is seen as a highly efficient and safe method. However, its large-scale industrial application is either limited by the high cost of the catalyst (usually a noble metal based catalyst) or by the low activity and poor reusability (usually a non-noble metal catalyst). In this study, we have successfully prepared three low-cost CuCo2O4 nanocatalysts, namely: (i) Ti supported CuCo2O4 film made of CuCo2O4 nanoplates, (ii) Ti supported CuCo2O4 film made of CuCo2O4 nanosheets, and (iii) unsupported CuCo2O4 nanoparticles. Among the three catalysts used for the hydrolytic dehydrogeneration of ammonia borane, the CuCo2O4 nanoplate film exhibits the highest catalytic activity with a turnover frequency (TOF) of ∼44.0 molhydrogen min-1 molcat-1. This is one of the largest TOF value for noble-metal-free catalysts ever reported in the literature. Moreover, the CuCo2O4 nanoplate film almost keeps its original catalytic activity after eight cycles, indicative of its high stability and good reusability. Owing to its advantages, the CuCo2O4 nanoplate film can be a promising catalyst for the hydrolytic dehydrogenation of ammonia borane, which may find important applications in the field of hydrogen energy.

  11. Liquid phase hydrogenation of acethydrazone to N'-methyl acethydrazide over Pd/γ-Al2O3 catalyst

    Directory of Open Access Journals (Sweden)

    S. G. Pakdehi

    2010-03-01

    Full Text Available Catalytic hydrogenation of acethydrazide (AH is the main step in the production of N'-methyl acethydrazide (MAH. In this step, AH reacts with formaldehyde to produce acetylhydrazone (AOH. AOH is hydrogenated in the presence of 5% Pd/γ-Al2O3 catalyst to MAH. In this paper, the effects of hydrogen pressure, catalyst loading and initial concentration of AOH on the initial rate of hydrogenation were studied in a batch slurry reactor within a temperature range of 303-333K. The hydrogenation rate was first order with respect to hydrogen concentration at lower hydrogen pressures. However, at higher pressures, the rate became independent of both hydrogen and initial AOH concentrations. A single site Langmuir-Hinshelwood type formulation was found to describe adequately the kinetic data. A good correlation was observed between the predicted concentration vs. time profiles and those determined experimentally. The apparent activation energy was calculated from the initial rates as 40.6 kJ/mol.

  12. The activation mechanism of Fe-based olefin metathesis catalysts

    Science.gov (United States)

    Poater, Albert; Pump, Eva; Vummaleti, Sai Vikrama Chaitanya; Cavallo, Luigi

    2014-08-01

    Density functional theory calculations have been used to describe the first turnover for olefin metathesis reaction of a homogenous Fe-based catalyst bearing a N-heterocyclic carbene ligand with methoxyethene as a substrate. Equal to conventional Ru-based catalysts, the activation of its Fe congener occurs through a dissociative mechanism, however with a more exothermic reaction energy profile. Predicted upper energy barriers were calculated to be on average ∼2 kcal/mol more beneficial for Fe catalyzed metathesis. Overall, this present computational study emphasises on advantages of Fe-based metathesis and gives a potential recipe for the design of an efficient Fe-based olefin metathesis catalysts.

  13. Effects of Potassium and Manganese Promoters on Nitrogen-Doped Carbon Nanotube-Supported Iron Catalysts for CO2 Hydrogenation

    Directory of Open Access Journals (Sweden)

    Praewpilin Kangvansura

    2017-06-01

    Full Text Available Nitrogen-doped carbon nanotubes (NCNTs were used as a support for iron (Fe nanoparticles applied in carbon dioxide (CO2 hydrogenation at 633 K and 25 bar (1 bar = 105 Pa. The Fe/NCNT catalyst promoted with both potassium (K and manganese (Mn showed high performance in CO2 hydrogenation, reaching 34.9% conversion with a gas hourly space velocity (GHSV of 3.1 L·(g·h−1. Product selectivities were high for olefin products and low for short-chain alkanes for the K-promoted catalysts. When Fe/NCNT catalyst was promoted with both K and Mn, the catalytic activity was stable for 60 h of reaction time. The structural effect of the Mn promoter was demonstrated by X-ray diffraction (XRD, temperature-programmed reduction (TPR with molecular hydrogen (H2, and in situ X-ray absorption near-edge structure (XANES analysis. The Mn promoter stabilized wüstite (FeO as an intermediate and lowered the TPR onset temperature. Catalytic ammonia (NH3 decomposition was used as an additional probe reaction for characterizing the promoter effects. The Fe/NCNT catalyst promoted with both K and Mn had the highest catalytic activity, and the Mn-promoted Fe/NCNT catalysts had the highest thermal stability under reducing conditions.

  14. Improved catalysts for hydrogen evolution reaction in alkaline solutions through the electrochemical formation of nickel-reduced graphene oxide interface.

    Science.gov (United States)

    Gutić, Sanjin J; Dobrota, Ana S; Leetmaa, Mikael; Skorodumova, Natalia V; Mentus, Slavko V; Pašti, Igor A

    2017-05-24

    H2 production via water electrolysis plays an important role in hydrogen economy. Hence, novel cheap electrocatalysts for the hydrogen evolution reaction (HER) are constantly needed. Here, we describe a simple method for the preparation of composite catalysts for H2 evolution, consisting in simultaneous reduction of the graphene oxide film, and electrochemical deposition of Ni on its surface. The obtained composites (Ni@rGO), compared to pure electrodeposited Ni, show an improved electrocatalytic activity towards HER in alkaline media. We found that the activity of the Ni@rGO catalysts depends on the surface composition (Ni vs. C mole ratio) and on the level of structural disorder of the rGO support. We suggest that HER activity is improved via Hads spillover from the Ni particles to the rGO support, where quick recombination to molecular hydrogen is favored. A deeper insight into such a mechanism of H2 production was achieved by kinetic Monte-Carlo simulations. These simulations enabled the reproduction of experimentally observed trends under the assumption that the support can act as a Hads acceptor. We expect that the proposed procedure for the production of novel HER catalysts could be generalized and lead to the development of a new generation of HER catalysts by tailoring the catalyst/support interface.

  15. Spectroscopic determination of hydrogenation rates and intermediates during carbonyl hydrogenation catalyzed by Shvo's hydroxycyclopentadienyl diruthenium hydride agrees with kinetic modeling based on independently measured rates of elementary reactions.

    Science.gov (United States)

    Casey, Charles P; Beetner, Sharon E; Johnson, Jeffrey B

    2008-02-20

    The catalytic hydrogenation of benzaldehyde and acetophenone with the Shvo hydrogenation catalysts were monitored by in situ IR spectroscopy in both toluene and THF. The disappearance of organic carbonyl compound and the concentrations of the ruthenium species present throughout the hydrogenation reaction were observed. The dependence of the hydrogenation rate on substrate, H2 pressure, total ruthenium concentration, and solvent were measured. In toluene, bridging diruthenium hydride 1 was the only observable ruthenium species until nearly all of the substrate was consumed. In THF, both 1 and some monoruthenium hydride 2 were observed during the course of the hydrogenation. A full kinetic model of the hydrogenation based on rate constants for individual steps in the catalysis was developed. This kinetic model simulates the rate of carbonyl compound hydrogenation and of the amounts of ruthenium species 1 and 2 present during hydrogenations.

  16. Catalytic decomposition of methane to COx-free hydrogen and carbon nanotubes over Co–W/MgO catalysts

    Directory of Open Access Journals (Sweden)

    Ahmed E. Awadallah

    2015-09-01

    Full Text Available Bimetallic catalysts containing a series of Co/W at 40/10, 30/20, 20/30 and 10/40 wt% supported on MgO with a total metal content of 50 wt% were prepared and used for the catalytic decomposition of methane to COx-free hydrogen and multi-walled carbon nanotubes (MWCNTs. The solid fresh and exhausted catalysts were characterized structurally and chemically through XRD, TPR, BET, TGA, TEM and Raman spectroscopy. The 40%Co–10%W/MgO catalyst exhibited the highest activity for the production of both hydrogen and MWCNTs. The formation of a large amount of non-interacted Co3O4 species is considered as the main reason for the catalyst superiority in its activity. On the contrary, catalysts formulations of 20%Co–30%W and 10%Co–40%W demonstrated the formation of a large amount of hardly reducible CoWO4 and MgWO4 particles causing lower activity of these catalysts toward methane decomposition as evidenced through the XRD and TPR results.

  17. Catalyst Degradation in High Temperature Proton Exchange Membrane Fuel Cells Based on Acid Doped Polybenzimidazole Membranes

    DEFF Research Database (Denmark)

    Cleemann, Lars Nilausen; Buazar, F.; Li, Qingfeng

    2013-01-01

    contribution of the membrane degradation to the performance losses during the potential cycling tests. As the major mechanism of the fuel cell performance degradation, the electrochemical active area of the cathodic catalysts showed a steady decrease in the cyclic voltammetric measurements, which was also...... and multi‐walled carbon nanotubes were used as supports for electrode catalysts and evaluated in accelerated durability tests under potential cycling at 150 °C. Measurements of open circuit voltage, area specific resistance and hydrogen permeation through the membrane were carried out, indicating little......Degradation of carbon supported platinum catalysts is a major failure mode for the long term durability of high temperature proton exchange membrane fuel cells based on phosphoric acid doped polybenzimidazole membranes. With Vulcan carbon black as a reference, thermally treated carbon black...

  18. Copolymerization of Ethylene and Propylene Using 4th Generation Ziegler- Natta Catalyst: Influence of Cocatalyst, External Electron Donor and Hydrogen

    Directory of Open Access Journals (Sweden)

    R. Mehtarani

    2007-08-01

    Full Text Available Copolymerization of ethylene and propylene was investigated using a 4th generation phthalate Ziegler-Natta catalyst in normal hexane in a Buchi reactor. The effects of different mole fractions of [Al]/[Ti], [Si]/[Al] and various amounts of hydrogen on productivity and weight percent of ethylene on the product, were studied. In the copolymerization reactions, tri-isobutyl aluminum (TiBAl was used as cocatalyst instead of triethyl aluminum (TEAl because TiBAl produced a more amorphous copolymer. In molar ratio [TiBAl]/[Ti] = 480 the catalyst activity was at maximum and ethylene content in this ratio was at minimum. Cyclohexyl-methyldimethoxy silane was used as external donor. In molar ratio [Si]/[TiBAl] = 0.05, the copolymer showed more amorphous behavior. In this molar ratio, the external donor decreased the productivity of the catalyst and a further increase of external donor concentration increased the productivity. Hydrogen increased the productivity of the catalyst and decreased the ethylene content of the copolymer in low concentration. In high concentration, however, hydrogen decreased the productivity and increased the ethylene content of the copolymer. Hydrogen as a chain transfer agent decreased the viscosity average molecular weight.

  19. Selective oxidation of methanol to hydrogen over gold catalysts promoted by alkaline-earth-metal and lanthanum oxides

    NARCIS (Netherlands)

    Hereijgers, B.P.C.|info:eu-repo/dai/nl/314131116; Weckhuysen, B.M.|info:eu-repo/dai/nl/285484397

    2009-01-01

    A series of alumina-supported gold catalysts was investigated for the CO-free production of hydrogen by partial oxidation of methanol. The addition of alkaline-earth metal oxide promoters resulted in a significant improvement of the catalytic performance. The methanol conversion was ca. 85 % with

  20. Hydrogenation of fast pyrolyis oil and model compounds in a two-phase aqueous organic system using homogeneous ruthenium catalysts

    NARCIS (Netherlands)

    Mahfud, F. H.; Ghijsen, F.; Heeres, H. J.

    2007-01-01

    The use of homogeneous ruthenium catalysts to hydrogenate the water-soluble fraction of pyrolysis oil is reported. Pyrolysis oil, which is obtained by fast pyrolysis of lignocellulosic biomass at 450-600 degrees C, contains significant amounts of aldehydes and ketones (e.g. 1-hydroxy-2-propanone (1)

  1. Fe catalysts for methane decomposition to produce hydrogen and carbon nano materials

    KAUST Repository

    Zhou, Lu

    2017-02-21

    Conducting catalytic methane decomposition over Fe catalysts is a green and economic route to produce H2 without CO/CO2 contamination. Fused 65wt% and impregnated 20wt% Fe catalysts were synthesized with different additives to investigate their activity, whereas showing Fe-Al2O3 combination as the best catalyst. Al2O3 is speculated to expose more Fe00 for the selective deposition of carbon nano tubes (CNTs). A fused Fe (65wt%)-Al2O3 sample was further investigated by means of H2-TPR, in-situ XRD, HRTEM and XAS to conclude 750°C is the optimized temperature for H2 pre-reduction and reaction to obtain a high activity. Based on density functional theory (DFT) study, a reaction mechanism over Fe catalysts was proposed to explain the formation of graphite from unstable supersaturated iron carbides decomposition. A carbon deposition model was further proposed which explains the formation of different carbon nano materials.

  2. A CATALYST, A PROCESS FOR SELECTIVE HYDROGENATION OF ACETYLENE TO ETHYLENE AND A METHOD FOR THE MANUFACTURE OF THE CATALYST

    DEFF Research Database (Denmark)

    2009-01-01

    A catalyst comprising a mixture of metal A selected from the group of Fe, Co and Ni and metal B selected from the group of Zn and Ga, and a support material, wherein the two metals are present in an intermetallic composition; A method for the manufacture of the catalyst; and the use of above...

  3. Superefficient thin film multilayer catalyst for generating hydrogen from sodium borohydride

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Lunghao [Department of Materials Engineering and Industrial Technologies, University of Trento, Via Mesiano 77, 38123 Trento (Italy); Department of Mechanical Engineering, University of Colorado, Boulder, CO 80309-0427 (United States); Ceccato, R. [Department of Materials Engineering and Industrial Technologies, University of Trento, Via Mesiano 77, 38123 Trento (Italy); Raj, R. [Department of Mechanical Engineering, University of Colorado, Boulder, CO 80309-0427 (United States)

    2011-01-15

    A multilayer catalyst consisting of a electrophoretically deposited thin film of carbon nanotubes (CNTs) on a substrate of carbon fibers, followed by a coating of polymer-derived silicon carbonitride (SiCN), which is then decorated with a monolayer of transition metals is shown to perform at the upperbound of the phenomemological prediction from an earlier work. A figure-of-merit for first order kinetics is equal to 4600 L min{sup -1}[NaBH{sub 4}]{sup -1}g{sub met}{sup -1}, which is nearly 30 times the value reported in literature, is achieved. This high FOM is attributed to the CNT-thin film, as opposed to the thick CNT-paper used in previous work, thus needing merely 0.15 wt% quantities of precious metals for effective catalysis. This new architecture corroborates the concepts that: (i) the catalytic activity derives mainly from the surface of the CNT substrate, and (ii) the silicon carbonitride interlayer is instrumental in dispersing the transition metals into a monolayer. The hydrogen generation rate (HGR) for zero order kinetics, which is obtained when [NaBH{sub 4}]> 0.03 M, is measured to be 75 L min{sup -1}g{sub met}{sup -1}, which is among the higher values reported in the literature. The present multilayer catalysts are able to perform without fading for many cycles, presumably because the bondings in the substrate are predominantly covalent. This feature adds further uniqueness to this multilayer catalyst. (author)

  4. A Nanomesoporous Catalyst from Modified Red Mud and Its Application for Methane Decomposition to Hydrogen Production

    Directory of Open Access Journals (Sweden)

    Xiaoke Fang

    2016-01-01

    Full Text Available A type of nanomesoporous modified red mud (MRM catalyst was prepared and utilized for catalytic methane decomposition (CMD to produce hydrogen. The modification process significantly simplified the mineral composition of the red mud (RM; in the meantime, the physical and chemical structure of RM was changed. TEM images suggested that MRM was a kind of nanomesoporous material assembled by a number of uniformly nanoscale particles, BET results showed that the pore size distributions of MRM were ranged from 3 to 12 nm, and the specific surface area and total pore volumes of red mud improved from 8.00 m2/g and 0.08 cm3/g to 190.61 m2/g and 0.39 cm3/g, respectively. The catalytic performance of the catalysts has been tested at 800°C; the results showed that MRM exhibited much higher activity and stability than RM for CMD.

  5. Synthesis and characterization of novel intermetallic catalysts for hydrogenation of carbon dioxide to methanol

    DEFF Research Database (Denmark)

    Fiordaliso, Elisabetta Maria; Sharafutdinov, Irek; Chorkendorff, Ib

    Novel Ni5Ga3 and Pd2Ga catalysts for CO2 hydrogenation to methanol are prepared by impregnation of aqueous Ni-Ga or Pd-Ga solutions of metal nitrates into high surface area SiO2, followed by drying, calcinations and reduction of the precursor in a H2 flow. Steady state experiments are performed...... in a reactor at atmospheric pressure and stoichiometric CO2/H2 mixture, while reaction products are analyzed by gas chromatography. The results are compared to the highly optimized Cu/ZnO/Al2O3. The activity and selectivity of the novel catalysts is close to that of Cu/ZnO/Al2O3 and the equilibrium conversion...... formation is observed after calcination. Size distribution analysis reveals that the Pd2Ga nanoparticles have a diameter of 5-10 nm which does not change after reduction, methanol synthesis and rapid ageing. Furthermore, in situ ETEM is used to monitor the development of the materials system during...

  6. Pt/Ceria-based Catalysts for Small Alcohol Electrooxidation

    Science.gov (United States)

    Menendez-Mora, Christian L.

    High emissions of fossil-based energy sources have led to scientists around the world to develop new alternatives for the future. In this sense, fuel cells are a remarkable and promising energy option with less environmental impact. The most used fuels for this technology are hydrogen and small chain alcohols, which can be oxidized to transform their chemical energy into electrical power. To do this, fuel cells need catalysts that will act as an active surface where the oxidation can take place. The problem with platinum catalysts is its possible CO poisoning with intermediates that are produced before the complete oxidation of alcohol to CO2. Different approaches have been taken to try to resolve this issue. In this case, cerium oxide (ceria) was selected as a co-catalyst to mitigate the effect of CO poisoning of platinum. Ceria is a compound that has the ability to work as an "oxygen tank" and can donate oxygen to carbon monoxide that is strongly adsorbed at platinum surface to produce CO2 (carbon dioxide), regenerating the Pt surface for further alcohol oxidation. Therefore, enhancing the current density as well as the power output of a fuel cell. First, an occlusion deposition technique was used to prepare platinum/ceria composite electrodes and tested them towards small chain alcohol oxidation such as methanol oxidation reaction in acidic and alkaline media. The preliminary results demonstrated that the Pt/ceria electrodes were more efficient towards methanol electrooxidation when compared to Pt electrodes. This enhancement was attributed to the presence of ceria. A second preparation method was selected for the synthesis of ceria/Pt catalysts. In this case, a hydrothermal method was used and the catalysis were studied for the effect of MeOH, EtOH and n-BuOH oxidation. The observed effect was that electrodes made of Pt/Pt:CeO2-x showed better catalytic effect than Pt/ceria and platinum electrodes. Moreover, a comparison between ceria nanorods versus

  7. Ruthenium-based olefin metathesis catalysts bearing pH-responsive ligands: External control of catalyst solubility and activity

    Science.gov (United States)

    Balof, Shawna Lynn

    2011-12-01

    Sixteen novel, Ru-based olefin metathesis catalysts bearing pH responsive ligands were synthesized. The pH-responsive groups employed with these catalysts included dimethylamino (NMe2) modified NHC ligands as well as N-donor dimethylaminopyridine (DMAP) and 3-(o-pyridyl)propylidene ligands. These pH-responsive ligands provided the means by which the solubility and/or activity profiles of the catalysts produced could be controlled via acid addition. The main goal of this dissertation was to design catalyst systems capable of performing ring opening metathesis (ROMP) and ring closing metathesis (RCM) reactions in both organic and aqueous media. In an effort to quickly gain access to new catalyst structures, a template synthesis for functionalized NHC ligand precursors was designed, in addition to other strategies, to obtain ligand precursors with ancillary NMe2 groups. Kinetic studies for the catalysts produced from these precursors showed external control of catalyst solubility was afforded via protonation of the NMe2 groups of their NHC ligands. Additionally, this protonation afforded external control of catalyst propagation rates for several catalysts. This is the first known independent external control for the propagation rates of ROMP catalysts. The incorporation of pH-responsive N-donor ligands into catalyst structures also provided the means for the external control of metathesis activity, as the protonation of these ligands resulted in an increased initiation rate based on their fast and irreversible dissociation from the metal center. The enhanced external control makes these catalysts applicable to a wide range of applications, some of which have been explored by us and/or through collaboration. Three of the catalysts designed showed remarkable metathesis activity in aqueous media. These catalysts displayed comparable RCM activity in aqueous media to a class of water-soluble catalysts reported by Grubbs et al., considered to be the most active catalyst for

  8. Formation of Multiple-Phase Catalysts for the Hydrogen Storage of Mg Nanoparticles by Adding Flowerlike NiS.

    Science.gov (United States)

    Xie, Xiubo; Ma, Xiujuan; Liu, Peng; Shang, Jiaxiang; Li, Xingguo; Liu, Tong

    2017-02-22

    In order to enhance the hydrogen storage properties of Mg, flowerlike NiS particles have been successfully prepared by solvothermal reaction method, and are subsequently ball milled with Mg nanoparticles (NPs) to fabricate Mg-5 wt % NiS nanocomposite. The nanocomposite displays Mg/NiS core/shell structure. The NiS shell decomposes into Ni, MgS and Mg2Ni multiple-phases, decorating on the surface of the Mg NPs after the first hydrogen absorption and desorption cycle at 673 K. The Mg-MgS-Mg2Ni-Ni nanocomposite shows enhanced hydrogenation and dehydrogenation rates: it can quickly uptake 3.5 wt % H2 within 10 min at 423 K and release 3.1 wt % H2 within 10 min at 573 K. The apparent hydrogen absorption and desorption activation energies are decreased to 45.45 and 64.71 kJ mol(-1). The enhanced sorption kinetics of the nanocomposite is attributed to the synergistic catalytic effects of the in situ formed MgS, Ni and Mg2Ni multiple-phase catalysts during the hydrogenation/dehydrogenation process, the porthole effects for the volume expansion and microstrain of the phase transformation of Mg2Ni and Mg2NiH4 and the reduced hydrogen diffusion distance caused by nanosized Mg. This novel method of in situ producing multiple-phase catalysts gives a new horizon for designing high performance hydrogen storage material.

  9. Non-conventional Pt-Cu alloy/carbon paper electrochemical catalyst formed by electrodeposition using hydrogen bubble as template

    Science.gov (United States)

    Kim, Youngkwang; Lee, Hyunjoon; Lim, Taeho; Kim, Hyun-Jong; Kwon, Oh Joong

    2017-10-01

    With emerging stability issues in fuel cell technology, a non-conventional catalyst not supported on carbon materials has been highlighted because it can avoid negative influences of carbon support materials on the stability, such as carbon corrosion. The nanostructured thin film catalyst is representative of non-conventional catalysts, which shows improved stability, enhanced mass specific activity, and fast mass transfer at high current densities. However, the nanostructured thin film catalyst usually requires multi-step processes for fabrication, making its mass production complex and irreproducible. We introduce a Pt-Cu alloy nanostructured thin film catalyst, which can be simply prepared by electrodeposition. By using hydrogen bubbles as a template, a three-dimensional free-standing foam of Cu was electrodeposited directly on the micro-porous layer/carbon paper and it was then displaced with Pt by simple immersion. The structure characterization revealed that a porous thin Pt-Cu alloy catalyst layer was successfully formed on the micro-porous layer/carbon paper. The synthesized Pt-Cu alloy catalyst exhibited superior durability compared to a conventional Pt/C in single cell test.

  10. Recycling of a spent iron based catalyst for the complete oxidation of toluene: effect of palladium.

    Science.gov (United States)

    Kim, Sang Chai; Nah, Jae Woon

    2015-01-01

    Complete oxidation of volatile organic compound (toluene) was carried out to assess the property and activity of the palladium-spent iron based catalyst. The properties of the prepared catalysts were characterized by using the Brunauer-Emmett-Teller method and by conducting temperature-programmed reduction, X-ray diffraction, X-ray photoelectron spectroscopy and field emission transmission electron microscopy. The addition of palladium to the spent iron based catalyst pretreated with oxalic acid shifted the conversion curve for the total oxidation of toluene to lower temperature. An increase in the toluene conversion due to palladium was highly related to the easier lattice oxygen mobility of the catalysts. Instrumental analysis suggested the presence of a strong interaction between palladium and iron oxide species. Moreover, in the case of reducing the Pd/Fe catalyst with hydrogen, palladium accelerated the reducing iron oxides, subsequently decreasing the toluene conversion. As a result, the oxidation states of palladium and iron had an important effect on the catalytic activity.

  11. Zr-Based MOF-808 as Meerwein–Ponndorf–Verley Reduction Catalyst for Challenging Carbonyl Compounds

    Directory of Open Access Journals (Sweden)

    Eva Plessers

    2016-07-01

    Full Text Available In the fine chemical industry, transfer hydrogenation of carbonyl compounds is an important route to selectively form the corresponding allyl alcohol. The Meerwein–Ponndorf–Verley reduction (MPV is catalyzed by a Lewis acid catalyst and easily oxidizable alcohols serve as hydrogen donor. We successfully used the Zr-based metal-organic framework (MOF MOF-808-P as MPV-catalyst with isopropyl alcohol as solvent and hydride donor. After only 2 h, 99% yield of cinnamyl alcohol was obtained. The highly active MOF-808-P is also a good catalyst for the selective reduction of more challenging substrates such as R-carvone and β-ionone. Two strategies were successfully used to shift the equilibrium towards the desired allylic alcohol products: (1 evaporation of formed acetone and (2 the use of the more strongly reducing 1-indanol. Carveol yield was increased to >70%. These results highlight the great potential of this recently discovered Zr-MOF as a chemically and thermally stable catalyst.

  12. Modifiers in rhodium catalysts for carbon monoxide hydrogenation: Structure-activity relationships

    Energy Technology Data Exchange (ETDEWEB)

    Bhore, N. A.

    1989-05-01

    This report is aimed at identifying interesting modified rhodium systems and elucidating structure-activity relationships in these systems with the overall goal of understanding the scientific issues in the catalytic conversion of syngas to oxygenates. Specific additives (sodium and molybdenum) are selected based on the scoping experiments. The effect of the additives on supported rhodium catalysts is then investigated. Throughout the investigation, experiments and analysis were performed on real systems instead of ideal systems. 374 refs., 82 figs., 57 tabs.

  13. Method of Heating a Foam-Based Catalyst Bed

    Science.gov (United States)

    Fortini, Arthur J.; Williams, Brian E.; McNeal, Shawn R.

    2009-01-01

    A method of heating a foam-based catalyst bed has been developed using silicon carbide as the catalyst support due to its readily accessible, high surface area that is oxidation-resistant and is electrically conductive. The foam support may be resistively heated by passing an electric current through it. This allows the catalyst bed to be heated directly, requiring less power to reach the desired temperature more quickly. Designed for heterogeneous catalysis, the method can be used by the petrochemical, chemical processing, and power-generating industries, as well as automotive catalytic converters. Catalyst beds must be heated to a light-off temperature before they catalyze the desired reactions. This typically is done by heating the assembly that contains the catalyst bed, which results in much of the power being wasted and/or lost to the surrounding environment. The catalyst bed is heated indirectly, thus requiring excessive power. With the electrically heated catalyst bed, virtually all of the power is used to heat the support, and only a small fraction is lost to the surroundings. Although the light-off temperature of most catalysts is only a few hundred degrees Celsius, the electrically heated foam is able to achieve temperatures of 1,200 C. Lower temperatures are achievable by supplying less electrical power to the foam. Furthermore, because of the foam s open-cell structure, the catalyst can be applied either directly to the foam ligaments or in the form of a catalyst- containing washcoat. This innovation would be very useful for heterogeneous catalysis where elevated temperatures are needed to drive the reaction.

  14. Hydrogen production from raw bioethanol steam reforming : optimization of catalyst composition with improved stability against various impurities

    Energy Technology Data Exchange (ETDEWEB)

    Le Valant, A.; Can, F.; Bion, N.; Epron, F.; Duprez, D. [Poitiers Univ., Poitiers (France). Laboratoire de Catalyse en Chimie organique

    2009-07-01

    This study investigated the effects of raw ethanol impurities on catalytic performance during ethanol steam reforming processes. An Rh/MgAI{sub 2}O{sub 4} reference catalyst was used. Steam reforming was conducted in a fixed bed reactor. The study showed that aldehyde, amine, and methanol have no negative impacts on catalytic performance. Deactivation is caused by coke formation as a result of the presence of the impurities in the feed. The composition of the support and metallic phases of the catalyst formulation were then modified in order to improve the stability of the catalyst in the presence of deactivating impurities. Rare earth elements were used to replace magnesium and decrease strong and medium acid sites. Ethanol conversion and hydrogen yield were both increased when the dehydration reaction was disfavoured. The metallic phase was modified by the addition of a second metal. It was concluded that the Rh-NiY-Al{sub 2}O{sub 3} catalyst has the highest hydrogen yield, and is more stable than the reference catalyst. 16 refs., 7 figs.

  15. Theoretical Studies in Heterogenous Catalysis: Towards a Rational Design of Novel Catalysts for Hydrodesulfurization and Hydrogen Production

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez,J.A.; Liu, P.

    2008-10-01

    important advantage of the cluster approach is that one can use the whole spectrum of quantum-chemical methods developed for small molecules with relatively minor modifications. On the other hand, the numerical effort involved in cluster calculations increases rather quickly with the size of the cluster. This problem does not exist when using slab models. Due to the explicit incorporation of the periodicity of the crystal lattice through the Bloch theorem, the actual dimension of a slab calculation depends only on the size of the unit cell. In practical terms, the slab approach is mainly useful for investigating the behavior of adsorbates at medium and high coverages. Very large unit cells are required at the limit of low to zero coverage, or when examining the properties and chemical behavior of isolated defect sites in a surface. In these cases, from a computational viewpoint, the cluster approach can be much more cost effective than the slab approach. Slab and cluster calculations can be performed at different levels of sophistication: semi-empirical methods, simple ab initio Hartree-Fock, ab initio post-Hartree-Fock (CI, MP2, etc), and density functional theory. Density-functional (DF) based calculations frequently give adsorption geometries with a high degree of accuracy and predict reliable trends for the energetics of adsorption reactions. This article provides a review of recent theoretical studies that deal with the behavior of novel catalysts used for hydrodesulfurization (HDS) reactions and the production of hydrogen (i.e. catalytic processes employed in the generation of clean fuels). These studies involve a strong coupling of theory and experiment. A significant fraction of the review is focused on the importance of size-effects and correlations between the electronic and chemical properties of catalytic materials. The article begins with a discussion of results for the desulfurization of thiophene on metal carbides and phosphides, systems which have the

  16. A Novel Synthesis of Gold Nanoparticles Supported on Hybrid Polymer/Metal Oxide as Catalysts for p-Chloronitrobenzene Hydrogenation

    Directory of Open Access Journals (Sweden)

    Cristian H. Campos

    2017-01-01

    Full Text Available This contribution reports a novel preparation of gold nanoparticles on polymer/metal oxide hybrid materials (Au/P[VBTACl]-M metal: Al, Ti or Zr and their use as heterogeneous catalysts in liquid phase hydrogenation of p-chloronitrobenzene. The support was prepared by in situ radical polymerization/sol gel process of (4-vinyl-benzyltrimethylammonium chloride and 3-(trimethoxysilylpropyl methacrylate in conjunction with metal-alkoxides as metal oxide precursors. The supported catalyst was prepared by an ion exchange process using chloroauric acid (HAuCl4 as gold precursor. The support provided the appropriate environment to induce the spontaneous reduction and deposition of gold nanoparticles. The hybrid material was characterized. TEM and DRUV-vis results indicated that the gold forms spherical metallic nanoparticles and that their mean diameter increases in the sequence, Au/P[VBTACl]-Zr > Au/P[VBTACl]-Al > Au/P[VBTACl]-Ti. The reactivity of the Au catalysts toward the p-CNB hydrogenation reaction is attributed to the different particle size distributions of gold nanoparticles in the hybrid supports. The kinetic pseudo-first-order constant values for the catalysts in the hydrogenation reaction increases in the order, Au/P[VBTACl]-Al > Au/P[VBTACl]-Zr > Au/P[VBTACl]-Ti. The selectivity for all the catalytic systems was greater than 99% toward the chloroaniline target product. Finally the catalyst supported on the hybrid with Al as metal oxide could be reused at least four times without loss in activity or selectivity for the hydrogenation of p-CNB in ethanol as solvent.

  17. Theoretical insights into the promotion effect of subsurface boron for the selective hydrogenation of CO to methanol over Pd catalysts.

    Science.gov (United States)

    Wu, Panpan; Yang, Bo

    2016-08-21

    The activity and selectivity of methanol synthesis from syngas have been studied for decades from both experimental and theoretical aspects. In this work, CO hydrogenation to methanol on both Pd(211) and subsurface boron-modified Pd(211) surfaces is investigated based on density functional theory calculations. Methane formation is considered as the main competitive reaction in the process and all the barriers and reaction energies involved are also calculated. We find that the modification of boron atoms will not alter the corresponding favored reaction pathways to produce methanol and methane on Pd(211), namely CO → CHO → CHOH → CH2OH → CH3OH for methanol formation and CO → COH → C → CH → CH2→ CH3→ CH4 for methane formation. In addition, by using a two-step model to estimate the effective barriers for methanol and methane formation, the activity and selectivity for the product formation could be obtained and compared. It is found that the addition of boron atoms would significantly increase the activity of methanol formation while the activity of methane formation on clean and boron modified Pd surfaces is similar. Furthermore, we find that the hydrogenation of CO over clean Pd(211) will give high methane selectivity, whilst the boron modified Pd(211) mainly produces methanol. All these observed results can be explained by the electronic interaction between boron atoms and local Pd atoms through the lattice strain effect and alloying effect, resulting in the downshift of the d-band center of surface Pd away from the Fermi level. Finally, an extended Brønsted-Evans-Polanyi (BEP) relationship is found between the energies of the transition states and the initial/final states for hydrogenation/dissociation reactions, which may provide significant insight into the activity and selectivity of the catalysts for methanol synthesis.

  18. Mesoporous silica nanoparticle supported PdIr bimetal catalyst for selective hydrogenation, and the significant promotional effect of Ir

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Hui; Huang, Chao; Yang, Fan [The Key Laboratory of Fuel Cell Technology of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641 (China); Yang, Xu [Key Laboratory of Renewable Energy, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou (China); Du, Li [The Key Laboratory of Fuel Cell Technology of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641 (China); Key Laboratory of Renewable Energy, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou (China); Liao, Shijun, E-mail: chsjliao@scut.edu.cn [The Key Laboratory of Fuel Cell Technology of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641 (China); Key Laboratory of Renewable Energy, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou (China)

    2015-12-01

    Graphical abstract: A mesoporous silica nanoparticle (MSN) supported bimetal catalyst, PdIr/MSN, was prepared by a facile impregnation and hydrogen reduction method. The strong promotional effect of Ir was observed and thoroughly investigated. At the optimal molar ratio of Ir to Pd (N{sub Ir}/N{sub Pd} = 0.1), the activity of PdIr{sub 0.1}/MSN was up to eight times and 28 times higher than that of monometallic Pd/MSN and Ir/MSN, respectively. The catalysts were characterized comprehensively by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and hydrogen temperature programmed reduction, which revealed that the promotional effect of Ir may be due to the enhanced dispersion of active components on the MSN, and to the intensified Pd–Ir electronic interaction caused by the addition of Ir. - Highlights: • Mesoporous nanoparticles were synthesized and used as support for metal catalyst. • PdIr bimetallic catalyst exhibited significantly improved hydrogenation activity. • The strong promotion of Ir was recognized firstly and investigated intensively. • PdIr exhibits 18 times higher activity than Pd to the hydrogenation of nitrobenzene. - Abstract: A mesoporous silica nanoparticle (MSN) supported bimetal catalyst, PdIr/MSN, was prepared by a facile impregnation and hydrogen reduction method. The strong promotional effect of Ir was observed and thoroughly investigated. At the optimal molar ratio of Ir to Pd (N{sub Ir}/N{sub Pd} = 0.1), the activity of PdIr{sub 0.1}/MSN was up to eight times and 28 times higher than that of monometallic Pd/MSN and Ir/MSN, respectively. The catalysts were characterized comprehensively by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and hydrogen temperature programmed reduction, which revealed that the promotional effect of Ir may be due to the enhanced dispersion of active components on the MSN, and to the intensified Pd–Ir electronic interaction

  19. Preparation of Co-Mo catalyst using activated carbon produced from egg shell and SiO2 as support – A hydrogenation study

    Directory of Open Access Journals (Sweden)

    Adeniyi Sunday Ogunlaja

    2010-12-01

    Full Text Available The preparation of a series of cobalt-molybdenum (Co-Mo catalysts supported on SiO2 and carbonized egg shells were investigated using standard procedures; the catalysts were further calcined at the 500 oC temperature to generate the internally consistent set, and the metal atoms content were varied in a regular manner. The ratio 1:4 (Co2+: Mo6+ by weight was employed for the various catalysts prepared. The carbonized egg shells were divided into two parts: the first part was leached with HNO3, as the other one was not leached. Activity tests were run using these catalysts containing leached and unleached carbon for the hydrogenation of methyl orange; the changes in absorbance regarding the unhydrogenated methyl orange at a wavelength of 460 nm were respectively 0.07 and 0.067 when the catalyst containing the leached carbonized egg shell (catalyst A and the catalyst containing the unleached activated carbon (catalyst B were used for the hydrogenation reaction. This confirms that catalyst A is more efficient in hydrogenating methyl orange than catalyst B.

  20. Recent advances in unveiling active sites in molybdenum sulfide-based electrocatalysts for the hydrogen evolution reaction

    Science.gov (United States)

    Seo, Bora; Joo, Sang Hoon

    2017-07-01

    Hydrogen has received significant attention as a promising future energy carrier due to its high energy density and environmentally friendly nature. In particular, the electrocatalytic generation of hydrogen fuel is highly desirable to replace current fossil fuel-dependent hydrogen production methods. However, to achieve widespread implementation of electrocatalytic hydrogen production technology, the development of highly active and durable electrocatalysts based on Earth-abundant elements is of prime importance. In this context, nanostructured molybdenum sulfides (MoS x ) have received a great deal of attention as promising alternatives to precious metal-based catalysts. In this focus review, we summarize recent efforts towards identification of the active sites in MoS x -based electrocatalysts for the hydrogen evolution reaction (HER). We also discuss recent synthetic strategies for the engineering of catalyst structures to achieve high active site densities. Finally, we suggest ongoing and future research challenges in the design of advanced MoS x -based HER electrocatalysts.

  1. The use of niobium based catalysts for liquid fuel production

    Directory of Open Access Journals (Sweden)

    Frank Martin Reguera

    2004-06-01

    Full Text Available The catalytic properties of niobium based catalysts were investigated in the conversion of oleic acid to liquid fuels at atmospheric pressure and at 623 K. The catalytic tests were performed in a fixed bed and continuous flow reactor using an acid to catalyst ratio equal to 4 and N2 as carrier gas. The reaction products were analyzed by gas chromatography and acidity measurements. NH3 temperature programmed desorption, N2 adsorption-desorption (BET method and Xray diffraction were also performed in order to determine the structural and acidic properties of the catalysts. From the catalytic tests, it was detected the formation of compounds in the range of gasoline, diesel and lubricant oils. Higher catalytic activity and selectivity for diesel fuel were observed for the catalysts NbOPO4 and H3PO4/Nb2O5 that possesses higher acidities and surface areas.

  2. Autothermal reforming of propane for hydrogen production over Pd/CeO{sub 2}/Al{sub 2}O{sub 3} catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Faria, Wagner L.S.; Dieguez, Lidia C.; Schmal, Martin [NUCAT/PEQ/COPPE, Federal University of Rio de Janeiro, C.P. 68502, 21945-970 Rio de Janeiro (Brazil)

    2008-12-17

    Steam reforming, partial oxidation and autothermal reforming of hydrocarbons are important routes to hydrogen generation for use in fuel cells. The propane autothermal reforming was studied in supported CeO{sub 2}/Al{sub 2}O{sub 3} based Pd catalysts, prepared with different Pd precursors. The reaction was carried out under different feedstock conditions and the catalytic activity was evaluated by temperature programmed surface reaction (TPSR). The effects of palladium precursors on the activity and selectivity were studied. Propane autothermal reforming showed three temperature ranges: at relative low temperatures total oxidation occurs; steam reforming occurs at intermediate temperatures when oxygen was completely consumed; and, finally, at higher temperatures the CO{sub 2} reforming prevails. The Pd acetylacetonate precursor catalyst was the most active, starting the reforming 100 K less than the Pd chlorine precursor catalyst. The presence of water in the reaction mixture was responsible for an increasing propane conversion and H{sub 2}/CO ratio when compared without water. Cerium oxide (CeO{sub 2}) was responsible for the decreasing CO concentration, promoting the water gas shift reaction (CO + H{sub 2}O {yields} CO{sub 2} + H{sub 2}). The catalysts were stable with time on stream during 50 h and a small deactivation occurs only at the beginning. (author)

  3. Efficient Pd@MIL-101(Cr) hetero-catalysts for 2-butyne-1,4-diol hydrogenation exhibiting high selectivity

    KAUST Repository

    Yin, Dongdong

    2017-01-05

    Pd@MIL-101(Cr) hetero-catalysts have been successfully prepared using the metal-organic chemical vapour deposition (MOCVD) approach, by choosing [Pd(η-CH)(η-CH)] as a volatile precursor, and the hydrothermally stable metal-organic framework, MIL-101(Cr) as a support. The prepared Pd@MIL-101(Cr) hetero-catalysts characterized with various analytical techniques, exhibited highly monodispersed immobilized Pd nanoparticles in the MIL-101(Cr) cavities, while retaining the pristine crystallinity and porosity. The intact hybrid Pd@MIL-101(Cr) has been demonstrated to be an efficient catalyst for 2-butyne-1,4-diol hydrogenation with excellent activity, stability and selectivity (2-butene-1,4-diol (>94%)).

  4. Carbon-Nanotube-Supported Bio-Inspired Nickel Catalyst and Its Integration in Hybrid Hydrogen/Air Fuel Cells.

    Science.gov (United States)

    Gentil, Solène; Lalaoui, Noémie; Dutta, Arnab; Nedellec, Yannig; Cosnier, Serge; Shaw, Wendy J; Artero, Vincent; Le Goff, Alan

    2017-02-06

    A biomimetic nickel bis-diphosphine complex incorporating the amino acid arginine in the outer coordination sphere was immobilized on modified carbon nanotubes (CNTs) through electrostatic interactions. The functionalized redox nanomaterial exhibits reversible electrocatalytic activity for the H2 /2 H(+) interconversion from pH 0 to 9, with catalytic preference for H2 oxidation at all pH values. The high activity of the complex over a wide pH range allows us to integrate this bio-inspired nanomaterial either in an enzymatic fuel cell together with a multicopper oxidase at the cathode, or in a proton exchange membrane fuel cell (PEMFC) using Pt/C at the cathode. The Ni-based PEMFC reaches 14 mW cm(-2) , only six-times-less as compared to full-Pt conventional PEMFC. The Pt-free enzyme-based fuel cell delivers ≈2 mW cm(-2) , a new efficiency record for a hydrogen biofuel cell with base metal catalysts. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. THE WILKINSON COMPLEX AS A HETEROGENEOUS CATALYST IN THE PARTIAL HYDROGENATION OF 1-HEPTYNE. REGENERATION OF THE COMPLEX

    Directory of Open Access Journals (Sweden)

    Edgardo Cagnola

    2016-06-01

    Full Text Available The Wilkinson complex was tested as a catalyst in the partial hydrogenation of 1-heptyne, a medium chain alkyne, at a temperature of T = 303 K and hydrogen pressure PH2 = 150 kPa. The tests were performed in homogeneous system as well as heterogeneous system, supporting the complex on i γ-Al2O3 and ii a commercial carbonaceous material, RX3. Characterization by means of XPS and FTIR revealed that the anchored complex did not lose its chemical identity, being the catalytically active species. The Wilkinson complex on RX3 showed better conversions and selectivities, higher than the Lindlar catalyst, used as a reference. Additionally, it was proposed a method to recover Rh as a metal from the remaining solutions, and from it regenerate the complex to be reused from it.

  6. Selective hydrogenation of phenol to cyclohexanone over Pd@CN (N-doped porous carbon): Role of catalyst reduction method

    Science.gov (United States)

    Hu, Shuo; Yang, Guangxin; Jiang, Hong; Liu, Yefei; Chen, Rizhi

    2018-03-01

    Selective phenol hydrogenation is a green and sustainable technology to produce cyclohexanone. The work focused on investigating the role of catalyst reduction method in the liquid-phase phenol hydrogenation to cyclohexanone over Pd@CN (N-doped porous carbon). A series of reduction methods including flowing hydrogen reduction, in-situ reaction reduction and liquid-phase reduction were designed and performed. The results highlighted that the reduction method significantly affected the catalytic performance of Pd@CN in the liquid-phase hydrogenation of phenol to cyclohexanone, and the liquid-phase reduction with the addition of appropriate amount of phenol was highly efficient to improve the catalytic activity of Pd@CN. The influence mechanism was explored by a series of characterizations. The results of TEM, XPS and CO chemisorption confirmed that the reduction method mainly affected the size, surface composition and dispersion of Pd in the CN material. The addition of phenol during the liquid-phase reduction could inhibit the aggregation of Pd NPs and promote the reduction of Pd (2+), and then improved the catalytic activity of Pd@CN. The work would aid the development of high-performance Pd@CN catalysts for selective phenol hydrogenation.

  7. A solar-powered microbial electrolysis cell with a platinum catalyst-free cathode to produce hydrogen.

    Science.gov (United States)

    Chae, Kyu-Jung; Choi, Mi-Jin; Kim, Kyoung-Yeol; Ajayi, Folusho F; Chang, In-Seop; Kim, In S

    2009-12-15

    This paper reports successful hydrogen evolution using a dye-sensitized solar cell (DSSC)-powered microbial electrolysis cell (MEC) without a Pt catalyst on the cathode, indicating a solution for the inherent drawbacks of conventional MECs, such as the need for an external bias and catalyst. DSSCs fabricated by assembling a ruthenium dye-loaded TiO(2) film and platinized FTO glass with an I(-)/I(3)(-) redox couple were demonstrated as an alternative bias (V(oc) = 0.65 V). Pt-loaded (0.3 mg Pt/cm(2)) electrodes with a Pt/C nanopowder showed relatively faster hydrogen production than the Pt-free electrodes, particularly at lower voltages. However, once the applied photovoltage exceeded a certain level (0.7 V), platinum did not have any additional effect on hydrogen evolution in the solar-powered MECs: hydrogen conversion efficiency was almost comparable for either the plain (71.3-77.0%) or Pt-loaded carbon felt (79.3-82.0%) at >0.7 V. In particular, the carbon nanopowder-coated electrode without Pt showed significantly enhanced performance compared to the plain electrode, which indicates efficient electrohydrogenesis, even without Pt by enhancing the surface area. As the applied photovoltage was increased, anodic methanogenesis decreased gradually, resulting in increasing hydrogen yield.

  8. Evidence of highly active cobalt oxide catalyst for the Fischer-Tropsch synthesis and CO2 hydrogenation.

    Science.gov (United States)

    Melaet, Gérôme; Ralston, Walter T; Li, Cheng-Shiuan; Alayoglu, Selim; An, Kwangjin; Musselwhite, Nathan; Kalkan, Bora; Somorjai, Gabor A

    2014-02-12

    Hydrogenations of CO or CO2 are important catalytic reactions as they are interesting alternatives to produce fine chemical feedstock hence avoiding the use of fossil sources. Using monodisperse nanoparticle (NP) catalysts, we have studied the CO/H2 (i.e., Fischer-Tropsch synthesis) and CO2/H2 reactions. Exploiting synchrotron based in situ characterization techniques such as XANES and XPS, we were able to demonstrate that 10 nm Co NPs cannot be reduced at 250 °C while supported on TiO2 or SiO2 and that the complete reduction of cobalt can only be achieved at 450 °C. Interestingly, cobalt oxide performs better than fully reduced cobalt when supported on TiO2. In fact, the catalytic results indicate an enhancement of 10-fold for the CO2/H2 reaction rate and 2-fold for the CO/H2 reaction rate for the Co/TiO2 treated at 250 °C in H2 versus Co/TiO2 treated at 450 °C. Inversely, the activity of cobalt supported on SiO2 has a higher turnover frequency when cobalt is metallic. The product distributions could be tuned depending on the support and the oxidation state of cobalt. For oxidized cobalt on TiO2, we observed an increase of methane production for the CO2/H2 reaction whereas it is more selective to unsaturated products for the CO/H2 reaction. In situ investigation of the catalysts indicated wetting of the TiO2 support by CoO(x) and partial encapsulation of metallic Co by TiO(2-x).

  9. Hydrogen production from raw bioethanol steam reforming: optimization of catalyst composition with improved stability against various impurities

    Energy Technology Data Exchange (ETDEWEB)

    Le Valant, A.; Can, F.; Bion, N.; Epron, F.; Duprez, D. [Laboratoire de Catalyse en Chimie organique, Univ. de Poitiers, Poitiers Cedex (France)], E-mail: florence.epron.cognet@univ-poitiers.fr

    2009-07-01

    Usually, ethanol steam reforming is performed using pure ethanol, whereas the use of raw bioethanol is of major importance for a cost effective industrial application. Raw bioethanol contains higher alcohols as the main impurities and also aldehydes, amines, acids and esters. The effect of these impurities on the catalytic performances for ethanol steam reforming (ESR) has been studied, using a reference catalyst, Rh/MgAl{sub 2}O{sub 4}. It was shown that the aldehyde, the amine and methanol has no negative effect on the catalytic performances, contrary to the ester, acid and higher alcohols. The deactivation is mainly explained by coke formation favored by the presence of these impurities in the feed. In order to improve the stability of the catalyst and its performances in the presence of these deactivating impurities, the catalyst formulation, i.e. the composition of the support and of the metallic phase, was modified. The addition of rare earth elements instead of magnesium to the alumina support leads to a decrease of the strong and medium acid sites and to an increase of the basicity. On these modified supports, the dehydration reaction, leading to olefins, which are coke precursors, is disfavored, the ethanol conversion and the hydrogen yield are increased. The best catalytic performances were obtained with Rh/Y-Al{sub 2}O{sub 3}. Then, the metallic phase was also modified by adding a second metal (Ni, Pt or Pd). The Rh-Ni/Y-Al{sub 2}O{sub 3} catalyst leads to the highest hydrogen yield. This catalyst, tested in the presence of raw bioethanol during 24h was very stable compared to the reference catalyst Rh/MgAl{sub 2}O{sub 4}, which was strongly deactivated after 2h of time-on-stream. (author)

  10. Hydrogen production from raw bioethanol steam reforming: Optimization of catalyst composition with improved stability against various impurities

    Energy Technology Data Exchange (ETDEWEB)

    Le Valant, Anthony; Can, Fabien; Bion, Nicolas; Duprez, Daniel; Epron, Florence [Laboratoire de Catalyse en Chimie organique, UMR6503 CNRS, Universite de Poitiers, 40 avenue du recteur Pineau, 86022 Poitiers Cedex (France)

    2010-05-15

    The use of raw bioethanol is of major importance for a cost effective industrial application. Raw bioethanol contains higher alcohols as the main impurities and also aldehydes, amines, acids and esters. The effect of these impurities on the catalytic performances for ethanol steam reforming (ESR) has been studied, using a reference catalyst, Rh/MgAl{sub 2}O{sub 4}. It was shown that the aldehyde, the amine and methanol have no negative effect on the catalytic performances, contrary to the ester, acid and higher alcohols. The deactivation is mainly explained by coke formation favored by the presence of these impurities in the feed. In order to improve the stability of the catalyst and its performances in the presence of these deactivating impurities, the catalyst formulation, i.e. the composition of the support and of the metallic phase, was modified. The addition of rare earth elements instead of magnesium to the alumina support leads to a decrease of the strong and medium acid sites and to an increase of the basicity. On these modified supports, the dehydration reaction, leading to olefins, which are coke precursors, is disfavored, the ethanol conversion and the hydrogen yield are increased. The best catalytic performances were obtained with Rh/Y-Al{sub 2}O{sub 3}. Then, the metallic phase was also modified by adding a second metal (Ni, Pt or Pd). The Rh-Ni/Y-Al{sub 2}O{sub 3} catalyst leads to the highest hydrogen yield. This catalyst, tested in the presence of raw bioethanol during 24 h was very stable compared to the reference catalyst Rh/MgAl{sub 2}O{sub 4}, which was strongly deactivated after 2 h of time-on -stream. (author)

  11. Selective alkyne hydrogenation over nano-metal systems: closing the gap between model and real catalysts for industrial applications.

    Science.gov (United States)

    Cárdenas-Lizana, Fernando; Crespo-Quesada, Micaela; Kiwi-Minsker, Lioubov

    2012-01-01

    The relationship between catalytic response and properties of the active phase is difficult to establish in classical heterogeneous catalysis due to the number of variables that can affect catalytic performance. Ultrahigh-vacuum surface methods applied to model catalyst surfaces are useful tools to assess fundamental issues related to catalytic processes but they are limited by the significant differences with catalysts in the working state. In an attempt to overcome this issue, (unsupported) nano-metal systems with controlled size and shape have been synthesized and tested in selective alkyne hydrogenation. The results revealed a dependency of nano-particles (NPs) morphology (size and shape) and allowed the identification of the active sites for this type of reaction. The nature of the stabilizer (steric and electrostatic stabilization) used in the NPs preparation has been shown to influence catalytic performance. The tailored active phase was subsequently immobilized on suitable nano- and micro-structured inorganic (e.g. 3D sintered metal fibers) supports with controlled surface properties in order to corroborate if the results obtained on the optimized nano-metal systems could be extrapolated to real catalysts. This article highlights the advantages and limitations of the analysis of selective alkyne hydrogenation over nano-metal systems that close the gap between model and real catalysts where the main challenges that lie ahead are summarized.

  12. Ni/Ce-MCM-41 mesostructured catalysts for simultaneous production of hydrogen and nanocarbon via methane decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Guevara, J.C.; Wang, J.A.; Chen, L.F.; Valenzuela, M.A. [ESIQIE, Instituto Politecnico Nacional, Col. Zacatenco, Av. Politecnico s/n, 07738 Mexico D. F. (Mexico); Salas, P. [Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, Apartado Postal 1-1010, Queretaro 76000 (Mexico); Garcia-Ruiz, A. [UPIICSA, Instituto Politecnico Nacional, Te 950 Col. Granjas-Mexico, 08400 Mexico D.F. (Mexico); Toledo, J.A.; Cortes-Jacome, M.A.; Angeles-Chavez, C. [Programa de Molecular Ingenieria, Instituto Mexicano del Petroleo, Eje Lazaro Cardenas 152, 07730 Mexico D. F. (Mexico); Novaro, O. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, A. P. 20-364, 01000 Mexico D.F. (Mexico)

    2010-04-15

    For the first time, simultaneous production of hydrogen and nanocarbon via catalytic decomposition of methane over Ni-loaded mesoporous Ce-MCM-41 catalysts was investigated. The catalytic performance of the Ni/Ce-MCM-41 catalysts is very stable and the reaction activity remained almost unchanged during 1400 min steam on time at temperatures 540, 560 and 580 C, respectively. The methane conversion level over these catalysts reached 60-75% with a 100% selectivity towards hydrogen. TEM observations revealed that most of the Ni particles located on the tip of the carbon nanofibers/nanotubes in the used catalysts, keeping their exposed surface clean during the test and thus remaining active for continuous reaction without obvious deactivation. Two kinds of carbon materials, graphitic carbon (C{sub g}) as major and amorphous carbon (C{sub A}) as minor were produced in the reaction, as confirmed by XRD analysis and TEM observations. Carbon nanofibers/nanotubes had an average diameter of approximately 30-50 nm and tens micrometers in length, depending on the reaction temperature, reaction time and Ni particle diameter. Four types of carbon nanofibers/nanotubes were detected and their formations greatly depend on the reaction temperature, time on steam and degree of the interaction between the metallic Ni and support. The respective mechanisms of the formation of nanocarbons were postulated and discussed. (author)

  13. Session 4: Production of hydrogen by oxidative reforming of ethanol on Pt/Al{sub 2}O{sub 3} catalysts doped with Ce and La

    Energy Technology Data Exchange (ETDEWEB)

    Navarro, R.M.; Alvarez-Galvan, M.C.; Fierro, J.L.G. [Instituto de Catalisis y Petroleoquimica (CSIC), Madrid (Spain); Rosa, F. [Centro de experimentacion de El Arenosillo (CEDEA). Instituto Nacional de Tecnica Aerospacial (INTA). Mazagon-Moguer, Huelva (Spain)

    2004-07-01

    The aim of this communication is to study the behaviour of a series of Pt catalysts supported on Al{sub 2}O{sub 3} modified with CeO{sub 2} and La{sub 2}O{sub 3} in the production of hydrogen from ethanol. Careful investigation of the catalyst structure was done in an attempt to establish a relationship between activity and structural and surface characteristics of the catalysts. (authors)

  14. Production of hydrogen from methanol over binary Cu/ZnO catalysts Part I. Catalyst preparation and characterisation

    NARCIS (Netherlands)

    Melián-Cabrera, Ignacio; Boutonnet, Magali; Agrell, Johan; Fierro, José L.G.

    2003-01-01

    Mixed copper–zinc oxide catalysts (Cu/ZnO) were prepared by two different techniques, i.e. from hydroxycarbonate precursors formed in aqueous solution and from oxalate precursors formed in water-in-oil microemulsion. Their physicochemical properties were characterised by nitrogen

  15. Hollow Pd/MOF Nanosphere with Double Shells as Multifunctional Catalyst for Hydrogenation Reaction.

    Science.gov (United States)

    Wan, Mingming; Zhang, Xinlu; Li, Meiyan; Chen, Bo; Yin, Jie; Jin, Haichao; Lin, Lin; Chen, Chao; Zhang, Ning

    2017-10-01

    A new type of hollow nanostructure featured double metal-organic frameworks shells with metal nanoparticles (MNPs) is designed and fabricated by the methods of ship in a bottle and bottle around the ship. The nanostructure material, hereinafter denoted as Void@HKUST-1/Pd@ZIF-8, is confirmed by the analyses of photograph, transmission electron microscopy, scanning electron microscopy, powder X-ray diffraction, inductively coupled plasma, and N 2 sorption. It possesses various multifunctionally structural characteristics such as hollow cavity which can improve mass transfer, the adjacent of the inner HKUST-1 shell to the void which enables the matrix of the shell to host and well disperse MNPs, and an outer ZIF-8 shell which acts as protective layer against the leaching of MNPs and a sieve to guarantee molecular-size selectivity. This makes the material eligible candidates for the heterogeneous catalyst. As a proof of concept, the liquid-phase hydrogenation of olefins with different molecular sizes as a model reaction is employed. It demonstrates the efficient catalytic activity and size-selectivity of Void@HKUST-1/Pd@ZIF-8. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Reverse microemulsion prepared Ni–Pt catalysts for methane cracking to produce COx-free hydrogen

    KAUST Repository

    Zhou, Lu

    2017-09-08

    A monodispersed 15 nm Ni9Pt1 catalyst synthesized via a reverse microemulsion method, shows a lower activation energy than both Ni and Pt catalysts during the methane cracking reaction. Thanks to the synergic effect of Ni–Pt alloy, this catalyst presents a stable H2 formation rate at 700 °C, and forms carbon nanotubes, anchoring the catalyst particles on top.

  17. Fundamental studies of supported bimetallic catalysts by NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Savargaonkar, Nilesh [Iowa State Univ., Ames, IA (United States)

    1996-10-17

    Various hydrogenation reactions on transition metals are important commercially whereas certain hydrogenolysis reactions are useful from fundamental point of view. Understanding the hydrogen mobility and kinetics of adsorption-desorption of hydrogen is important in understanding the mechanisms of such reactions involving hydrogen. The kinetics of hydrogen chemisorption was studied by means of selective excitation NMR on silica supported Pt, Rh and Pt-Rh catalysts. The activation energy of hydrogen desorption was found to be lower on silica supported Pt catalysts as compared to Rh and Pt-Rh catalysts. It was found that the rates of hydrogen adsorption and desorption on Pt-Rh catalyst were similar to those on Rh catalyst and much higher as compared to Pt catalyst. The Ru-Ag bimetallic system is much simpler to study than the Pt-Rh system and serves as a model system to characterize more complicated systems such as the K/Ru system. Ag was found to decrease the amounts of adsorbed hydrogen and the hydrogen-to-ruthenium stoichiometry. Ag reduced the populations of states with low and intermediate binding energies of hydrogen on silica supported Ru catalyst. The rates of hydrogen adsorption and desorption were also lower on silica supported Ru-Ag catalyst as compared to Ru catalyst. This report contains introductory information, the literature review, general conclusions, and four appendices. An additional four chapters and one appendix have been processed separately for inclusion on the data base.

  18. Hydrogenation using iron oxide-based nanocatalysts for the synthesis of amines.

    Science.gov (United States)

    Jagadeesh, Rajenahally V; Stemmler, Tobias; Surkus, Annette-Enrica; Junge, Henrik; Junge, Kathrin; Beller, Matthias

    2015-04-01

    In this protocol, we describe the preparation of nanoscale iron oxide-based materials and their use in the catalysis of different hydrogenation reactions. Pyrolysis of a Fe(OAc)2-phenanthroline complex on carbon at 800 °C under argon atmosphere results in the formation of nanoscale Fe2O3 particles surrounded by nitrogen-doped graphene layers. By applying these catalysts, the hydrogenation of structurally diverse and functionalized nitroarenes to anilines proceeds with excellent selectivity. Furthermore, we have shown that one-pot reductive amination of carbonyl compounds with nitroarenes is also possible in the presence of these iron oxide catalysts. We report herein the synthesis of more than 40 amines, which are important feedstocks and key intermediates for pharmaceuticals, agrochemicals and polymers. The detailed preparation of the catalysts and the procedures for the hydrogenation processes are presented. The overall time required for the catalyst preparation and for the hydrogenation reactions are 35 h and 20-35 h, respectively.

  19. The activation mechanism of Fe-based olefin metathesis catalysts

    KAUST Repository

    Poater, Albert

    2014-08-01

    Density functional theory calculations have been used to describe the first turnover for olefin metathesis reaction of a homogenous Fe-based catalyst bearing a N-heterocyclic carbene ligand with methoxyethene as a substrate. Equal to conventional Ru-based catalysts, the activation of its Fe congener occurs through a dissociative mechanism, however with a more exothermic reaction energy profile. Predicted upper energy barriers were calculated to be on average ∼2 kcal/mol more beneficial for Fe catalyzed metathesis. Overall, this present computational study emphasises on advantages of Fe-based metathesis and gives a potential recipe for the design of an efficient Fe-based olefin metathesis catalysts. © 2014 Elsevier B.V.

  20. Preparation and Characterization of Sugar Based Catalyst on Various Supports

    Directory of Open Access Journals (Sweden)

    Jidon Adrian Janaun

    2017-04-01

    Full Text Available A novel structured carbon-based acid catalyst was prepared by depositing the carbon precursor onto glass, ceramic and aluminum supports via dip-coating method, followed by carbonization process for converting the d-glucose layer into black carbon char in an inert nitrogen environment at 400 °C. Then, the –SO3H group was introduced into the framework of the carbon char by multiple vapor phase sulfonation. Four different carbonization methods were carried out (dry pyrolysis and hydrothermal carbonization with or without pressurized in the catalyst preparation while among the carbonization methods, the samples which prepared from dry pyrolysis without pressurized process showed the strong acidity due to highest adsorption of acid group in the catalyst surface although the catalyst attached onto the support was the least compared to other preparation methods. Among the catalysts, the sulfonated carbon-base catalyst that is attached on the ceramic support exhibited the highest aci-dity (1.327 mmol/g followed by the catalyst deposited on the glass (0.917 mmol/g and aluminum (0.321 mmol/g supports. The porous structure of ceramic surface, allowed a better interaction between reactants and –SO3H site in the carbon. Through the FT-IR analysis, it was observed that the functional groups –COOH, –OH, and –SO3H were present in the active sites of the catalysts. The surface areas of  glass (Si–SC, ceramic (Ce–SC and aluminum (Al–SC catalysts were larger than 1 m2/g, whereas the pore size belongs to macroporous as the average pore size is more than 50 nm. It is also stable within the temperature of 400 °C as there was less than 10% weight loss revealed from the TGA analysis. Copyright © 2017 BCREC GROUP. All rights reserved Received: 20th April 2016; Revised: 14th October 2016; Accepted: 17th October 2016 How to Cite: Janaun, J.A., Mey, T.J., Bono, A., Krishnaiah, D. (2017. Preparation and Characterization of Sugar Based Catalyst on Various

  1. Pt-based Bi-metallic Monolith Catalysts for Partial Upgrading of Microalgae Oil

    Energy Technology Data Exchange (ETDEWEB)

    Lawal, Adeniyi [Stevens Inst. of Technology, Hoboken, NJ (United States); Manganaro, James [Anasyn LLC, Princeton, NJ (United States); Goodall, Brian [Valicor Renewables LLC, Dexter, MI (United States); Farrauto, Robert [Columbia Univ., New York, NY (United States)

    2015-03-24

    Valicor’s proprietary wet extraction process in conjunction with thermochemical pre-treatment was performed on algal biomass from two different algae strains, Nannochloropsis Salina (N.S.) and Chlorella to produce algae oils. Polar lipids such as phospholipids were hydrolyzed, and metals and metalloids, known catalyst poisons, were separated into the aqueous phase, creating an attractive “pre-refined” oil for hydrodeoxygenation (HDO) upgrading by Stevens. Oil content and oil extraction efficiency of approximately 30 and 90% respectively were achieved. At Stevens, we formulated a Pt-based bi-metallic catalyst which was demonstrated to be effective in the hydro-treating of the algae oils to produce ‘green’ diesel. The bi-metallic catalyst was wash-coated on a monolith, and in conjunction with a high throughput high pressure (pilot plant) reactor system, was used in hydrotreating algae oils from N.S. and Chlorella. Mixtures of these algae oils and refinery light atmospheric gas oil (LAGO) supplied by our petroleum refiner partner, Marathon Petroleum Corporation, were co-processed in the pilot plant reactor system using the Pt-based bi-metallic monolith catalyst. A 26 wt% N.S. algae oil/74 wt % LAGO mixture hydrotreated in the reactor system was subjected to the ASTM D975 Diesel Fuel Specification Test and it met all the important requirements, including a cetane index of 50.5. An elemental oxygen analysis performed by an independent and reputable lab reported an oxygen content of trace to none found. The successful co-processing of a mixture of algae oil and LAGO will enable integration of algae oil as a refinery feedstock which is one of the goals of DOE-BETO. We have presented experimental data that show that our precious metal-based catalysts consume less hydrogen than the conventional hydrotreating catalyst NiMo Precious metal catalysts favor the hydrodecarbonylation/hydrodecarboxylation route of HDO over the dehydration route preferred by base metal

  2. Bifunctional Nanostructured Base Catalysts: Opportunities for BioFuels

    Energy Technology Data Exchange (ETDEWEB)

    Connor, William

    2010-12-30

    ABSTRACT This research studied and develop novel basic catalysts for production of renewable chemicals and fuels from biomass. We will focus on the development of unique porous structural-base catalysts formed by two techniques: from (mixed) metal-oxide bases and by nitrogen substitution for oxygen in zeolites. These catalysts will be compared to conventional solid base materials for aldol condensation, catalytic fast pyrolysis, and transesterification reactions. These reactions are important in processes that are currently being commercialized for production of fuels from biomass and will be pivotal in future biomass conversion to fuels and chemicals. Specifically, we have studied the aldol-condensation of acetone with furfural over oxides and zeolites, the conversion of sugars by rapid pyrolysis over zeolites and the trans-esterification of vegetable oil with methanol over mixed oxide catalysts. Our previous research has indicated that the base strength of framework nitrogen in nitrogen-substituted zeolites (NH-zeolites) is nearly twice as strong as in standard zeolites. Nitrogen substituted catalysts have been synthesized from several zeolites (including FAU, MFI, BEA, and LTL) using NH3 treatment.

  3. Production of biodiesel from mixed waste vegetable oil using an aluminium hydrogen sulphate as a heterogeneous acid catalyst.

    Science.gov (United States)

    Ramachandran, Kasirajan; Sivakumar, Pandian; Suganya, Tamilarasan; Renganathan, Sahadevan

    2011-08-01

    Al(HSO(4))(3) heterogeneous acid catalyst was prepared by the sulfonation of anhydrous AlCl(3). This catalyst was employed to catalyze transesterification reaction to synthesis methyl ester when a mixed waste vegetable oil was used as feedstock. The physical and chemical properties of aluminum hydrogen sulphate catalyst were characterized by scanning electron microscopy (SEM) measurements, energy dispersive X-ray (EDAX) analysis and titration method. The maximum conversion of triglyceride was achieved as 81 wt.% with 50 min reaction time at 220°C, 16:1 molar ratio of methanol to oil and 0.5 wt.% of catalyst. The high catalytic activity and stability of this catalyst was related to its high acid site density (-OH, Brönsted acid sites), hydrophobicity that prevented the hydration of -OH group, hydrophilic functional groups (-SO(3)H) that gave improved accessibility of methanol to the triglyceride. The fuel properties of methyl ester were analyzed. The fuel properties were found to be observed within the limits of ASTM D6751. Copyright © 2011 Elsevier Ltd. All rights reserved.

  4. Carbon induced selective regulation of cobalt-based Fischer-Tropsch catalysts by ethylene treatment.

    Science.gov (United States)

    Zhai, Peng; Chen, Pei-Pei; Xie, Jinglin; Liu, Jin-Xun; Zhao, Huabo; Lin, Lili; Zhao, Bo; Su, Hai-Yan; Zhu, Qingjun; Li, Wei-Xue; Ma, Ding

    2017-04-28

    Various carbonaceous species were controllably deposited on Co/Al2O3 catalysts using ethylene as carbon source during the activation process for Fischer-Tropsch synthesis (FTS). Atomic, polymeric and graphitic carbon were distinguished by Raman spectroscopy, thermoanalysis and temperature programmed hydrogenation. Significant changes occurred in both the catalytic activity and selectivity toward hydrocarbon products after ethylene treatment. The activity decreased along with an increase in CH4 selectivity, at the expense of a remarkable decrease of heavy hydrocarbon production, resulting in enhanced selectivity for the gasoline fraction. In situ XPS experiments show the possible electron transfer from cobalt to carbon and the blockage of metallic cobalt sites, which is responsible for the deactivation of the catalyst. DFT calculations reveal that the activation barrier (Ea) of methane formation decreases by 0.61 eV on the carbon-absorbed Co(111) surface, whereas the Ea of the CH + CH coupling reaction changes unnoticeably. Hydrogenation of CHx to methane becomes the preferable route among the elementary reactions on the Co(111) surface, leading to dramatic changes in the product distribution. Detailed coke-induced deactivation mechanisms of Co-based catalysts during FTS are discussed.

  5. Enhancement of oxyanion and diatrizoate reduction kinetics using selected azo dyes on Pd-based catalysts.

    Science.gov (United States)

    Shuai, Danmeng; Chaplin, Brian P; Shapley, John R; Menendez, Nathaniel P; McCalman, Dorrell C; Schneider, William F; Werth, Charles J

    2010-03-01

    Azo dyes are widespread pollutants and potential cocontaminants for nitrate; we evaluated their effect on catalytic reduction of a suite of oxyanions, diatrizoate, and N-nitrosodimethylamine (NDMA). The azo dye methyl orange significantly enhanced (less than or equal to a factor of 5.24) the catalytic reduction kinetics of nitrate, nitrite, bromate, perchlorate, chlorate, and diatrizoate with several different Pd-based catalysts; NDMA reduction was not enhanced. Nitrate was selected as a probe contaminant, and a variety of azo dyes (methyl orange, methyl red, fast yellow AB, metanil yellow, acid orange 7, congo red, eriochrome black T, acid red 27, acid yellow 11, and acid yellow 17) were evaluated for their ability to enhance reduction. Hydrogenation energies of azo dyes were calculated using density functional theory and a volcano relationship between hydrogenation energies and reduction rate enhancement was observed. A kinetic model based on Brønsted-Evans-Polanyi (BEP) theory matched the volcano relationship and suggests sorbed azo dyes enhance reduction kinetics through hydrogen atom shuttling between reduced azo dyes (i.e., hydrazo dyes) and oxyanions or diatrizoate. This is the first research that has identified this synergetic effect, and it has implications for designing more efficient catalysts and reducing Pd costs in water treatment systems.

  6. Particle size effect for cobalt Fischer-Tropsch catalysts based on in situ CO chemisorption

    Science.gov (United States)

    Yang, Jia; Frøseth, Vidar; Chen, De; Holmen, Anders

    2016-06-01

    The cobalt particle size effect on activity and selectivity for CO hydrogenation was revisited on cobalt catalysts supported on a large variety of supports at 483 K, 1.85 bar, and H2/CO/Ar = 15/1.5/33.5 Nml/min. The size dependence of the activity and selectivity was analyzed in terms of site coverage and rate constants based on SSITKA experimental results. It was found that the Co particle size index estimated by the conventional method, namely, ex situ hydrogen chemisorption, could not correlate well the activity and selectivity as a function of the particle size index. The same holds for the site coverage of CO and intermediates leading to methane formation. However, the cobalt particle size index based on in situ CO chemisorption measured at 373 K provides a good correlation for turnover frequencies (TOFs) at reaction conditions. It was observed that TOF for CO conversion (TOFCO) increased with increasing particle size index of cobalt and SSITKA experiments showed that this was possibly due to increased site coverage of CO. The TOF for methane formation (TOFCH4) increased with particle size and remained constant at higher particle sizes possibly due to combined effect from the site coverage of intermediates leading to methane (θCHx) and the pseudo-first-order rate constant (kt). The results suggest that the support can play an important role for the size dependence of the activity and selectivity of CO hydrogenation on Co catalysts.

  7. Carbon Dioxide Dry Reforming of Glycerol for Hydrogen Production using Ni/ZrO2 and Ni/CaO as Catalysts

    Directory of Open Access Journals (Sweden)

    Nur Nabillah Mohd Arif

    2016-08-01

    Full Text Available Glycerol, byproduct from the biodiesel production can be effectively utilized as the promising source of synthesis gas (syngas through a dry reforming reaction. Combination of these waste materials with greenhouse gases which is carbon dioxide (CO2 will help to reduce environmental problem such as global warming. This dry reforming reaction has been carried out in a fixed bed batch reactor at 700 °C under the atmospheric pressure for 3 hours. In this experiment, reforming reaction was carried out using Nickel (Ni as based catalyst and supported with zirconium (ZrO2 and calcium (CaO oxides. The catalysts were prepared by wet impregnation method and characterized using Bruanaer-Emmett-Teller (BET surface area, Scanning Electron Microscopy (SEM, X-ray Diffraction (XRD, Thermo Gravimetric (TGA, and Temperature Programmed Reduction (TPR analysis. Reaction studies show that 15% Ni/CaO give the highest hydrogen yield and glycerol conversion that peaked at 24.59% and 30.32%, respectively. This result is verified by XRD analysis where this catalyst shows low crystallinity and fine dispersion of Ni species resulted in high specific surface area which gives 44.93 m2/g that is validated by BET.  Copyright © 2016 BCREC GROUP. All rights reserved Received: 21st January 2016; Revised: 24th February 2016; Accepted: 29th February 2016 How to Cite: Arif, N.M.M., Vo, D.V.N., Azizan,M.T., Abidin S.Z. (2016. Carbon Dioxide Dry Reforming of Glycerol for Hydrogen Production using Ni/ZrO2 and Ni/CaO as Catalysts. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (2: 200-209 (doi:10.9767/bcrec.11.2.551.200-209 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.11.2.551.200-209

  8. Catalyst and its use for the manufacture of methane from gases containing carbon monoxide and dioxide and hydrogen. [preparation of nickel catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Broecker, F.J.; Zirker, G.; Triebskorn, B.; Marosi, L.; Schwarzmann, M.; Dethlefsen, W.; Kaempfer, K.

    1975-10-14

    An improved nickel catalyst from West Germany's BASF AG allows the production of methane from carbon monoxide, carbon dioxide, and hydrogen at a lower feedstock temperature of only 392/sup 0/ to 572/sup 0/F (200/sup 0/ to 300/sup 0/C). The catalyst is manufactured by precipitating the compound Ni/sub 6/Al/sub 2/(OH)/sub 16/CO/sub 3/ x 4H/sub 2/O from aqueous solution, drying it at a temperature of 176/sup 0/ to 356/sup 0/F (80/sup 0/ to 180/sup 0/C), calcining it at a temperature of 572/sup 0/ to 1022/sup 0/F (300/sup 0/ to 550/sup 0/C), and subsequently reducing it in a stream of hydrogen. Between the drying stage and the calcination stage, the temperature is raised at a rate of 3/sup 0/ to 6/sup 0/F (1.66/sup 0/ to 3.33/sup 0/C)/min.

  9. Poisoning of vanadia based SCR catalysts by potassium:influence of catalyst composition and potassium mobility

    DEFF Research Database (Denmark)

    Olsen, Brian Kjærgaard; Kügler, Frauke; Jensen, Anker Degn

    2016-01-01

    The deactivation of V2O5–(WO3)/TiO2 catalysts for selective catalytic reduction (SCR) of NOx upon exposure to aerosols of KCl or K2SO4, at different temperatures, has been studied. All samples exposed for more than 240 hours lost a substantial fraction of their initial activity although lower...... aerosol (mass based distribution mode:1.3 μm) compared to that of the KCl aerosol (mass based distribution mode: 0.12 μm). The relative activities of exposed catalysts indicate that promotion with WO3 accelerates the deactivation, likely due to theenhanced Brønsted acidity which appears to promote...

  10. Hydrogen Production by Steam Reforming of Liquefied Natural Gas (LNG) Over Nickel-Phosphorus-Alumina Xerogel Catalyst Prepared by a Carbon-Templating Epoxide-Driven Sol-Gel Method.

    Science.gov (United States)

    Bang, Yongju; Park, Seungwon; Han, Seung Ju; Yoo, Jaekyeong; Choi, Jung Ho; Kang, Tae Hun; Lee, Jinwon; Song, In Kyu

    2016-05-01

    A nickel-phosphorus-alumina xerogel catalyst was prepared by a carbon-templating epoxide-driven sol-gel method (denoted as CNPA catalyst), and it was applied to the hydrogen production by steam reforming of liquefied natural gas (LNG). For comparison, a nickel-phosphorus-alumina xerogel catalyst was also prepared by a similar method in the absence of carbon template (denoted as NPA catalyst). The effect of carbon template addition on the physicochemical properties and catalytic activities of the catalysts in the steam reforming of LNG was investigated. Both CNPA and NPA catalysts showed excellent textural properties with well-developed mesoporous structure. However, CNPA catalyst retained a more reducible nickel aluminate phase than NPA catalyst. XRD analysis of the reduced CNPA and NPA catalysts revealed that nickel sintering on the CNPA catalyst was suppressed compared to that on the NPA catalyst. From H2-TPD and CH4-TPD measurements of the reduced CNPA and NPA catalysts, it was also revealed that CNPA catalyst with large amount of hydrogen uptake and strong hydrogen-binding sites showed larger amount of methane adsorption than NPA catalyst. In the hydrogen production by steam reforming of LNG, CNPA catalyst with large methane adsorption capacity showed a better catalytic activity than NPA catalyst.

  11. Down Select Report of Chemical Hydrogen Storage Materials, Catalysts, and Spent Fuel Regeneration Processes - May 2008

    Energy Technology Data Exchange (ETDEWEB)

    Ott, Kevin C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Linehan, Sue [Rohm and Haas, Philadelphia, PA (United States); Lipiecki, Frank [Rohm and Haas, Philadelphia, PA (United States); Christopher, Aardahl L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2008-05-12

    Chemical Hydrogen Storage Center of Excellence FY2008 Second Quarter Milestone Report: Technical report describing assessment of hydrogen storage materials and progress towards meeting DOE’s hydrogen storage targets.

  12. Enhanced performance and stability of high temperature proton exchange membrane fuel cell by incorporating zirconium hydrogen phosphate in catalyst layer

    Science.gov (United States)

    Barron, Olivia; Su, Huaneng; Linkov, Vladimir; Pollet, Bruno G.; Pasupathi, Sivakumar

    2015-03-01

    Zirconium hydrogen phosphate (ZHP) together with polytetrafluoroethylene (PTFE) polymer binder is incorporated into the catalyst layers (CLs) of ABPBI (poly(2,5-benzimidazole))-based high temperature polymer electrolyte membrane fuel cell (HT-PEMFCs) to improve its performance and durability. The influence of ZHP content (normalised with respect to dry PTFE) on the CL properties are structurally characterised by scanning electron microscopy (SEM) and mercury intrusion porosimetry. Electrochemical analyses of the resultant membrane electrode assemblies (MEAs) are performed by recording polarisation curves and impedance spectra at 160 °C, ambient pressure and humidity. The result show that a 30 wt.% ZHP/PTFE content in the CL is optimum for improving fuel cell performance, the resultant MEA delivers a peak power of 592 mW cm-2 at a cell voltage of 380 mV. Electrochemical impedance spectra (EIS) indicate that 30% ZHP in the CL can increase the proton conductivity compared to the pristine PTFE-gas diffusion electrode (GDE). A short term stability test (∼500 h) on the 30 wt.% ZHP/PTFE-GDE shows a remarkable high durability with a degradation rate as low as ∼19 μV h-1 at 0.2 A cm-2, while 195 μV h-1 was obtained for the pristine GDE.

  13. Supramolecular water oxidation with rubda-based catalysts

    KAUST Repository

    Richmond, Craig J.

    2014-11-05

    Extremely slow and extremely fast new water oxidation catalysts based on the Rubda (bda = 2,2′-bipyri-dine-6,6′-dicarboxylate) systems are reported with turnover frequencies in the range of 1 and 900 cycless"1, respectively. Detailed analyses of the main factors involved in the water oxidation reaction have been carried out and are based on a combination of reactivity tests, electrochemical experiments, and DFT calculations. These analyses give a convergent interpretation that generates a solid understanding of the main factors involved in the water oxidation reaction, which in turn allows the design of catalysts with very low energy barriers in all the steps involved in the water oxidation catalytic cycle. We show that for this type of system p-stacking interactions are the key factors that influence reactivity and by adequately controlling them we can generate exceptionally fast water oxidation catalysts.

  14. Pt/SnO2-based CO-oxidation catalysts for CO2 lasers

    Science.gov (United States)

    Upchurch, Billy T.; Schryer, David R.; Hess, Robert V.; Brown, Kenneth G.; Van Norman, John D.

    1990-01-01

    The activity of Pt/SnO2-based CO-oxidation catalysts has been maximized by optimizing pretreatment conditions and catalyst formulation. The role of H2O in activating these catalysts and of CO2 retention in deactivating them has been determined as has the interaction of these catalysts with rare-isotope C(0-18) and (O-18)2.

  15. Two-dimensional boron: Lightest catalyst for hydrogen and oxygen evolution reaction

    Energy Technology Data Exchange (ETDEWEB)

    Mir, Showkat H. [Centre for Nano Science, Central University of Gujarat, Gandhinagar 382030 (India); Chakraborty, Sudip, E-mail: sudiphys@gmail.com, E-mail: prakash.jha@cug.ac.in; Wärnå, John [Condensed Matter Theory Group, Department of Physics and Astronomy, Uppsala University, Uppsala 75120 (Sweden); Jha, Prakash C., E-mail: sudiphys@gmail.com, E-mail: prakash.jha@cug.ac.in [School of Applied Material Sciences, Central University of Gujarat, Gandhinagar 382030 (India); Soni, Himadri [Lehrstuhl für Theoretische Chemie, Friedrich-Alexander Universität Erlangen-Nürnberg, Egerlandstraße 3, 91058 Erlangen (Germany); Jha, Prafulla K. [Department of Physics, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara 390 002 (India); Ahuja, Rajeev [Condensed Matter Theory Group, Department of Physics and Astronomy, Uppsala University, Uppsala 75120 (Sweden); Department of Materials and Engineering, Royal Institute of Technology (KTH), 10044 Stockholm (Sweden)

    2016-08-01

    The hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) have been envisaged on a two-dimensional (2D) boron sheet through electronic structure calculations based on a density functional theory framework. To date, boron sheets are the lightest 2D material and, therefore, exploring the catalytic activity of such a monolayer system would be quite intuitive both from fundamental and application perspectives. We have functionalized the boron sheet (BS) with different elemental dopants like carbon, nitrogen, phosphorous, sulphur, and lithium and determined the adsorption energy for each case while hydrogen and oxygen are on top of the doping site of the boron sheet. The free energy calculated from the individual adsorption energy for each functionalized BS subsequently guides us to predict which case of functionalization serves better for the HER or the OER.

  16. A comparative parametric study of a catalytic plate methane reformer coated with segmented and continuous layers of combustion catalyst for hydrogen production

    Science.gov (United States)

    Mundhwa, Mayur; Parmar, Rajesh D.; Thurgood, Christopher P.

    2017-03-01

    A parametric comparison study is carried out between segmented and conventional continuous layer configurations of the coated combustion-catalyst to investigate their influence on the performance of methane steam reforming (MSR) for hydrogen production in a catalytic plate reactor (CPR). MSR is simulated on one side of a thin plate over a continuous layer of nickel-alumina catalyst by implementing an experimentally validated surface microkinetic model. Required thermal energy for the MSR reaction is supplied by simulating catalytic methane combustion (CMC) on the opposite side of the plate over segmented and continuous layer of a platinum-alumina catalyst by implementing power law rate model. The simulation results of both coating configurations of the combustion-catalyst are compared using the following parameters: (1) co-flow and counter-flow modes between CMC and MSR, (2) gas hourly space velocity and (3) reforming-catalyst thickness. The study explains why CPR designed with the segmented combustion-catalyst and co-flow mode shows superior performance not only in terms of high hydrogen production but also in terms of minimizing the maximum reactor plate temperature and thermal hot-spots. The study shows that the segmented coating requires 7% to 8% less combustion-side feed flow and 70% less combustion-catalyst to produce the required flow of hydrogen (29.80 mol/h) on the reforming-side to feed a 1 kW fuel-cell compared to the conventional continuous coating of the combustion-catalyst.

  17. Attrition resistant catalysts and sorbents based on heavy metal poisoned FCC catalysts

    Science.gov (United States)

    Gangwal, Santosh; Jothimurugesan, Kandaswamy

    1999-01-01

    A heavy metal poisoned, spent FCC catalyst is treated by chemically impregnating the poisoned catalyst with a new catalytic metal or metal salt to provide an attrition resistant catalyst or sorbent for a different catalytic or absorption processes, such as catalysts for Fischer-Tropsh Synthesis, and sorbents for removal of sulfur gasses from fuel gases and flue-gases. The heavy metal contaminated FCC catalyst is directly used as a support for preparing catalysts having new catalytic properties and sorbents having new sorbent properties, without removing or "passivating" the heavy metals on the spent FCC catalyst as an intermediate step.

  18. Design and assembly of a catalyst bed gas generator for the catalytic decomposition of high concentration hydrogen peroxide propellants and the catalytic combustion of hydrocarbon/air mixtures

    Science.gov (United States)

    Lohner, Kevin A. (Inventor); Mays, Jeffrey A. (Inventor); Sevener, Kathleen M. (Inventor)

    2004-01-01

    A method for designing and assembling a high performance catalyst bed gas generator for use in decomposing propellants, particularly hydrogen peroxide propellants, for use in target, space, and on-orbit propulsion systems and low-emission terrestrial power and gas generation. The gas generator utilizes a sectioned catalyst bed system, and incorporates a robust, high temperature mixed metal oxide catalyst. The gas generator requires no special preheat apparatus or special sequencing to meet start-up requirements, enabling a fast overall response time. The high performance catalyst bed gas generator system has consistently demonstrated high decomposition efficiency, extremely low decomposition roughness, and long operating life on multiple test articles.

  19. Experimental and kinetic modeling studies on the biphasic hydrogenation of levulinic acid to gamma-valerolactone using a homogeneous water-soluble Ru-(TPPTS) catalyst

    NARCIS (Netherlands)

    Chalid, M.; Broekhuis, A. A.; Heeres, H. J.

    2011-01-01

    gamma-Valerolactone (GVL) is considered a very attractive biomass derived platform chemical. This paper describes the application of biphasic homogeneous catalysis for the hydrogenation of levulinic acid (LA) to GVL using molecular hydrogen. A water soluble Ru-catalyst made in situ from RuCl3 center

  20. Synthesis of DME by CO2 hydrogenation over La2O3-modified CuO-ZnO-ZrO2/HZSM-5 catalysts

    Directory of Open Access Journals (Sweden)

    Zhang Yajing

    2017-01-01

    Full Text Available A series of La2O3-modified CuO-ZnO-ZrO2/HZSM-5 catalysts were prepared by an oxalate co-precipitation method. The catalysts were fully characterized by X-ray diffraction (XRD, N2 adsorption-desorption, hydrogen temperature pro-grammed reduction (H2-TPR, ammonia temperature programmed desorption (NH3-TPD, and X-ray photoelectron spectroscopy (XPS techniques. The effect of the La2O3 content on the structure and performance of the catalysts was thoroughly investigated. The catalysts were evaluated for the direct synthesis of dimethyl ether (DME from CO2 hydrogenation. The results displayed that La2O3 addition enhanced catalytic performance, and the maximal CO2 conversion (34.3% and DME selectivity (57.3% were obtained over the catalyst with 1% La2O3, which due to the smaller size of Cu species and a larger ratio of Cu+/Cu.

  1. Photoswitching a Molecular Catalyst to Regulate CO2 Hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Priyadarshani, Nilusha [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Ginovska-Pangovska, Bojana [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Bays, J. Timothy [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Linehan, John C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Shaw, Wendy J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-07-24

    Inspired by nature’s ability to regulate catalysis using physiological stimuli, azobenzene was incorporated into Rh(bis)diphosphine CO2 hydrogenation catalysts to photoinitiate structural changes to modulate the resulting catalytic activity. The rhodium bound diphosphine ligands (P(Ph2)-CH2-N(R) CH2-P(Ph2)) contain the terminal amine of a non-natural amino acid, either β-alanine (β-Ala) or γ-aminobutyric acid (GABA). For both β-ala and GABA containing complexes, the carboxylic acids of the amino acids were coupled to the amines of diaminoazobenzene, creating a rhodium bound trans-spanning tetraphosphine complex. The photo-induced cis-trans isomerization of the azobenzene-containing complexes imposes structural changes on these complexes, as evidenced by 1H NMR. We found that the CO2 hydrogenation activity for the β-ala bound Rh complex is 40% faster with azobenzene in the cis configuration (16 s-1) than in the trans conformation (11 s-1), while the γ-aminobutyric acid containing Rh complex has the same rate (~17 s-1) in either the cis or the trans configuration at 27 °C. The corresponding complexes without the attached azobenzene were also prepared, characterized, and catalytically tested for comparison, and have rates of 30 s-1. Computational studies were undertaken to evaluate the difference in rate between the cis and trans isomers for the β-Ala bound Rh complex, and revealed major structural changes between all cis and trans structures, but only minor structural changes that would be unique to the β-Ala bound Rh complex. We postulate that the slower rate of the azobenzene-containing β-Ala bound Rh complex is due to subtle changes in the bite angle arising from steric strain due to the trans-spanning azobenzene, altering hydricity and consequently rate. This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy

  2. Catalyst element, reactor comprising such catalyst element, die for producing such catalyst element, and method for the hydrogenating conversion of an oil

    NARCIS (Netherlands)

    Sie, S.T.; Cybulski, A.; Moulijn, J.A.

    1994-01-01

    There is described a catalyst element (1) consisting of an integral whole having channels (2) extending therethrough. These channels (2) have, in circumferential sense of the cross section thereof, at least one concave wall portion and at least one convex wall portion, preferably provided by

  3. Iridium Ziegler-Type Hydrogenation Catalysts Made from [(1,5-COD)Ir( -O2C8H15)]2 and AlEt3: Spectroscopic and Kinetic Evidence for the Irn Species Present and for Nanoparticles as the Fastest Catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Alley, W.; Hamdemir, I; Wang, Q; Frenkel, A; Li, L; Yang, J; Menard, L; Nuzzo, R; Ozkar, S; Finke, R

    2010-01-01

    Ziegler-type hydrogenation catalysts, those made from a group 8-10 transition metal precatalyst and an AlR{sub 3} cocatalyst, are often used for large scale industrial polymer hydrogenation; note that Ziegler-type hydrogenation catalysts are not the same as Ziegler-Natta polymerization catalysts. A review of prior studies of Ziegler-type hydrogenation catalysts (Alley et al. J. Mol. Catal. A: Chem. 2010, 315, 1-27) reveals that a {approx}50 year old problem is identifying the metal species present before, during, and after Ziegler-type hydrogenation catalysis, and which species are the kinetically best, fastest catalysts-that is, which species are the true hydrogenation catalysts. Also of significant interest is whether what we have termed 'Ziegler nanoclusters' are present and what their relative catalytic activity is. Reported herein is the characterization of an Ir Ziegler-type hydrogenation catalyst, a valuable model (vide infra) for the Co-based industrial Ziegler-type hydrogenation catalyst, made from the crystallographically characterized [(1,5-COD)Ir({mu}-O{sub 2}C{sub 8}H{sub 15})]{sub 2} precatalyst plus AlEt{sub 3}. Characterization of this Ir model system is accomplished before and after catalysis using a battery of physical methods including Z-contrast scanning transmission electron microscopy (STEM), high resolution (HR)TEM, and X-ray absorption fine structure (XAFS) spectroscopy. Kinetic studies plus Hg(0) poisoning experiments are then employed to probe which species are the fastest catalysts. The main findings herein are that (i) a combination of the catalyst precursors [(1,5-COD)Ir({mu}-O{sub 2}C{sub 8}H{sub 15})]{sub 2} and AlEt{sub 3} gives catalytically active solutions containing a broad distribution of Ir{sub n} species ranging from monometallic Ir complexes to nanometer scale, noncrystalline Ir{sub n} nanoclusters (up to Ir{sub {approx}100} by Z-contrast STEM) with the estimated mean Ir species being 0.5-0.7 nm, Ir{sub {approx}4

  4. THE EFFECT OF MAGNETITE (Fe3O4CATALYST FROM IRON SANDS ON DESORPTION TEMPERATURE OF MgH2 HYDROGEN STORAGE MATERIAL

    Directory of Open Access Journals (Sweden)

    Maulinda Maulinda

    2016-03-01

    Full Text Available One of the future technologies for a safe hydrogen storage media is  metal hydrides. Currently, Mg-based metal hydride has a safety factor and efficient for vehicle applications. However, the thermodynamic properties of magnesium hydride (MgH2 found a relatively high temperature. High desorption temperatures caused MgH2 high thermodynamic stability resulting desorption enthalpy is also high. In this study, natural mineral (iron ore has been extracted from iron sand into powder of magnetite (Fe3O4 and used as a catalyst in an effort to improve the desorption properties of MgH2. Magnetie has been successfully extracted from iron sand using precipitation method with a purity of 85 % , where the purity of the iron sand before extracted was 81%. Then, MgH2-Fe3O4 was milling using mechanical alloying method with a variety of catalysts and milling time. The observation by XRD showed the material was reduced to nanocrystalline scale. MgH2 phase appears as the main phase. DSC test results showed with the addition of Fe3O4, the desorption temperature can be reduced up to 366oC, compared to pure pure MgH2 reached by 409o C. Furthermore, based on gravimetric test, the hydrogen release occurs at a temperature of 388o C, weight loss  of 0.66 mg during 16 minutes.

  5. Mechanistic insight into sonochemical biodiesel synthesis using heterogeneous base catalyst.

    Science.gov (United States)

    Choudhury, Hanif A; Chakma, Sankar; Moholkar, Vijayanand S

    2014-01-01

    The beneficial effect of ultrasound on transesterification reaction is well known. Heterogeneous (or solid) catalysts for biodiesel synthesis have merit that they do not contaminate the byproduct of glycerol. In this paper, we have attempted to identify the mechanistic features of ultrasound-enhanced biodiesel synthesis with the base-catalyst of CaO. A statistical design of experiments (Box-Behnken) was used to identify the influence of temperature, alcohol to oil molar ratio and catalyst loading on transesterification yield. The optimum values of these parameters for the highest yield were identified through Response Surface Method (with a quadratic model) and ANOVA. These values are: temperature=62 °C, molar ratio=10:1 and catalyst loading=6 wt.%. The activation energy was determined as 82.3 kJ/mol, which is higher than that for homogeneous catalyzed system (for both acidic and basic catalyst). The experimental results have been analyzed vis-à-vis simulations of cavitation bubble dynamics. Due to 3-phase heterogeneity of the system, the yield was dominated by intrinsic kinetics, and the optimum temperature for the highest yield was close to boiling point of methanol. At this temperature, the influence of cavitation bubbles (in terms of both sonochemical and sonophysical effect) is negligible, and ultrasonic micro-streaming provided necessary convection in the system. The influence of all parameters on the reaction system was found to be strongly inter-dependent. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Single domain PEMFC model based on agglomerate catalyst geometry

    Science.gov (United States)

    Siegel, N. P.; Ellis, M. W.; Nelson, D. J.; von Spakovsky, M. R.

    A steady two-dimensional computational model for a proton exchange membrane (PEM) fuel cell is presented. The model accounts for species transport, electrochemical kinetics, energy transport, current distribution, and water uptake and release in the catalyst layer. The governing differential equations are solved over a single computational domain, which consists of a gas channel, gas diffusion layer, and catalyst layer for both the anode and cathode sides of the cell as well as the solid polymer membrane. The model for the catalyst regions is based on an agglomerate geometry, which requires water species to exist in both dissolved and gaseous forms simultaneously. Data related to catalyst morphology, which was required by the model, was obtained via a microscopic analysis of a commercially available membrane electrode assembly (MEA). The coupled set of differential equations is solved with the commercial computational fluid dynamics (CFD) solver, CFDesign™, and is readily adaptable with respect to geometry and material property definitions. The results show that fuel cell performance is highly dependent on catalyst structure, specifically the relative volume fractions of gas pores and polymer membrane contained within the active region as well as the geometry of the individual agglomerates.

  7. The effect of poly-N-vinylpyrrolidone modification on NiCoB catalysts for hydrogenation of p-chloronitrobenzene

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Bin [Department of Chemical Engineering, Nanocatalysis Research Center, National Central University, Chung-Li 320, Taiwan (China); Chen Yuwen, E-mail: ywchen@cc.ncu.edu.tw [Department of Chemical Engineering, Nanocatalysis Research Center, National Central University, Chung-Li 320, Taiwan (China)

    2011-02-15

    A series of poly-N-vinylpyrrolidone (PVP)-modified NiCoB catalysts with various PVP contents were prepared by chemical reduction method. The Ni and Co cations were reduced by NaBH{sub 4} at room temperature. PVP was added during preparation. The materials were characterized by X-ray diffraction, transmission electron microscopy, and differential scanning calorimeter. The results showed that all samples possessed amorphous structure. After washing, the residual PVP adsorbed on the surface of NiCoB and acted as a spacer to prevent NiCoB particles from aggregation and agglomeration. The liquid-phase hydrogenation of p-chloronitrobenzene was carried out to investigate the catalytic properties of the PVP-modified NiCoB catalysts. The catalytic activities of NiCoB catalysts decreased by modifying with PVP but the selectivities for p-chloroaniline improved significantly. The competitive adsorption of PVP with p-chloronitrobenzene and p-chloroaniline on the NiCoB nanoparticles was responsible for the catalytic performance. The amount of the PVP played a key role in the hydrogenation reaction.

  8. Au-Based Catalysts: Electrochemical Characterization for Structural Insights

    Directory of Open Access Journals (Sweden)

    Valentina Pifferi

    2016-02-01

    Full Text Available Au-based catalysts are widely used in important processes because of their peculiar characteristics. The catalyst performance depends strongly on the nature and structure of the metal nanoparticles, especially in the case of bimetallic catalysts where synergistic effects between the two metals can be occasionally seen. In this paper, it is shown that electrochemical characterisation (cyclovoltammetry CV and electrochemical impedance spectroscopy EIS of AuPd systems can be used to determine the presence of an electronic interaction between the two metals, thus providing a strong support in the determination of the nature of the synergy between Au and Pd in the liquid phase oxidation of alcohols. However, it seems likely that the strong difference in the catalytic behavior between the single metals and the bimetallic system is connected not only to the redox behaviour, but also to the energetic balance between the different elementary steps of the reaction.

  9. Palladium-Based Catalysts as Electrodes for Direct Methanol Fuel Cells: A Last Ten Years Review

    Directory of Open Access Journals (Sweden)

    Juan Carlos Calderón Gómez

    2016-08-01

    Full Text Available Platinum-based materials are accepted as the suitable electrocatalysts for anodes and cathodes in direct methanol fuel cells (DMFCs. Nonetheless, the increased demand and scarce world reserves of Pt, as well as some technical problems associated with its use, have motivated a wide research focused to design Pd-based catalysts, considering the similar properties between this metal and Pt. In this review, we present the most recent advancements about Pd-based catalysts, considering Pd, Pd alloys with different transition metals and non-carbon supported nanoparticles, as possible electrodes in DMFCs. In the case of the anode, different reported works have highlighted the capacity of these new materials for overcoming the CO poisoning and promote the oxidation of other intermediates generated during the methanol oxidation. Regarding the cathode, the studies have showed more positive onset potentials, as fundamental parameter for determining the mechanism of the oxygen reduction reaction (ORR and thus, making them able for achieving high efficiencies, with less production of hydrogen peroxide as collateral product. This revision suggests that it is possible to replace the conventional Pt catalysts by Pd-based materials, although several efforts must be made in order to improve their performance in DMFCs.

  10. Environmentally Benign Bifunctional Solid Acid and Base Catalysts

    NARCIS (Netherlands)

    Elmekawy, A.; Shiju, N.R.; Rothenberg, G.; Brown, D.R.

    2014-01-01

    Solid bifunctional acid-​base catalysts were prepd. in two ways on an amorphous silica support: (1) by grafting mercaptopropyl units (followed by oxidn. to propylsulfonic acid) and aminopropyl groups to the silica surface (NH2-​SiO2-​SO3H)​, and (2) by grafting only aminopropyl groups and then

  11. Multi-walled carbon nanotubes as catalyst promoter for dimethyl ether synthesis from CO{sub 2} hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Zha, Fei, E-mail: zhafei@nwnu.edu.cn [College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China); Tian, Haifeng; Yan, Jun [College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China); Chang, Yue [College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China); Key Laboratory of Polymer Material of Gansu Province, Lanzhou 730070 (China)

    2013-11-15

    The mixed acid of H{sub 2}SO{sub 4}/HNO{sub 3}-pretreated multi-walled carbon nanotubes was employed as supports and ultrasound-assisted co-precipitation method was designed to prepare multi-walled carbon nanotubes supported CuO–ZnO–Al{sub 2}O{sub 3}/HZSM-5 catalyst. The catalyst was characterized by means of X-ray diffraction spectrum (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), thermal analysis (TG) and Brunauer–Emmett–Teller (BET). The catalyst activity for the preparation of dimethyl ether from hydrogenation of CO{sub 2} was investigated in a fixed-bed reactor, which showed that multi-walled carbon nanotubes could promote the catalyst activity of CuO–ZnO–Al{sub 2}O{sub 3}/HZSM-5. Under the reaction conditions of temperature at 262 °C, pressure at 3.0 MPa, H{sub 2}/CO{sub 2} = 3 (volume ratio) and space velocity (SV) = 1800 mL g{sub cat}{sup −1} h{sup −1}, the conversion per pass of carbon dioxide was 46.2%, with the dimethyl ether yield and selectivity of 20.9% and 45.2%.

  12. A smart strategy to fabricate Ru nanoparticle inserted porous carbon nanofibers as highly efficient levulinic acid hydrogenation catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ying; Sun, Cheng-Jun; Brown, Dennis E.; Zhang, Liqiang; Yang, Feng; Zhao, Hairui; Wang, Yue; Ma, Xiaohui; Zhang, Xin; Ren, Yang

    2016-01-01

    Herein, we first put forward a smart strategy to in situ fabricate Ru nanoparticle (NP) inserted porous carbon nanofibers by one-pot conversion of Ru-functionalized metal organic framework fibers. Such fiber precursors are skillfully constructed by cooperative assembly of different proportional RuCl3 and Zn(Ac)2·2H2O along with trimesic acid (H3BTC) in the presence of N,N-dimethylformamide. The following high-temperature pyrolysis affords uniform and evenly dispersed Ru NPs (ca. 12-16 nm), which are firmly inserted into the hierarchically porous carbon nanofibers formed simultaneously. The resulting Ru-carbon nanofiber (Ru-CNF) catalysts prove to be active towards the liquid-phase hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL), a biomass-derived platform molecule with wide applications in the preparation of renewable chemicals and liquid transportation fuels. The optimal GVL yield of 96.0% is obtained, corresponding to a high activity of 9.23 molLAh–1gRu–1, 17 times of that using the commercial Ru/C catalyst. Moreover, the Ru-CNF catalyst is extremely stable, and can be cycled up to 7 times without significant loss of reactivity. Our strategy demonstrated here reveals new possibilities to make proficient metal catalysts, and provides a general way to fabricate metal-carbon nanofiber composites available for other applications.

  13. Phenol oxidation kinetics in water solution using iron(3)-oxide-based nano-catalysts.

    Science.gov (United States)

    Zelmanov, Grigory; Semiat, Raphael

    2008-08-01

    The influence of inorganic ions (HCO(3), PO(4)/HPO(4)/H(2)PO(4), Cl, SO(4), Ca, Na and Mg) on the advanced chemical oxidation process of organic compounds dissolved in water is reported here. The catalytic behavior of iron(3)-oxide-based nano-particles was investigated together with inorganic ions and hydrogen peroxide concentrations, and pH level. Phenol was chosen as a typical organic contaminant for this study as a simulating pollutant. The limiting concentrations of radical scavengers making the oxidation process inefficient were identified. The strong effect of concentration of radical scavengers HCO(3), PO(4)/HPO(4)/H(2)PO(4), the nano-catalyst and hydrogen peroxide concentrations, and pH on the phenol oxidation rate and lag time period before reaction starts was determined. It was shown that Cl, SO(4), Ca, Na and Mg ions had no significant effect on the kinetics of phenol oxidation.

  14. Studying PW-Amberlite catalyst deactivation in limonene epoxidation by hydrogen peroxide

    Directory of Open Access Journals (Sweden)

    Rolando Barrera Zapata

    2010-07-01

    95% and 97% when ethanol or acetone were used as washing solvents, respectively. Leaching tests showed that the reaction did not continue when the catalyst was removed from the reaction mixture, confirming the absence of leaching during the catalyst’s active phase. FTIR analysis revealed that the characteristic species of the phosphotungstate complex did not vary with successive reusing of the catalyst.

  15. Performance of metal alloys as hydrogen evolution reaction catalysts in a microbial electrolysis cell

    NARCIS (Netherlands)

    Jeremiasse, A.W.; Bergsma, J.; Kleijn, J.M.; Saakes, M.; Buisman, C.J.N.; Cohen Stuart, M.A.; Hamelers, H.V.M.

    2011-01-01

    H2 can be produced from organic matter with a microbial electrolysis cell (MEC). To decrease the energy input and increase the H2 production rate of an MEC, a catalyst is used at the cathode. Platinum is an effective catalyst, but its high costs stimulate searching for alternatives, such as

  16. Catalytic performance and characterization of cobalt-nickel nano catalysts for CO hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Feyzi, Mostafa; Gholivand, Mohammad Bagher [Razi University, Kermanshah (Iran, Islamic Republic of); Babakhanian, Arash [Islamic Azad University, Kermanshah (Iran, Islamic Republic of)

    2014-01-15

    A series of Co-Ni nano catalysts were prepared by co-precipitation method. We investigated the effect of Co/Ni molar ratios precipitate and calcination conditions on the catalytic performance of cobalt nickel catalysts for Fisher-Tropsch synthesis (FTS). The catalyst containing 90%Co/10%Ni was found to be optimal for the conversion of synthesis gas to light olefins. The activity and selectivity of the optimal catalyst were studied in different operational conditions. The results show that the best operational conditions are the H{sub 2}/CO=2/1 molar feed ratio at 310 .deg. C and GHSV=1,200 h{sup -}1 under 5 bar of pressure. The prepared catalysts were characterized by powder X-ray diffraction (XRD), N{sub 2} adsorption-desorption measurements such as BET and BJH methods, transmission electron microscopy (TEM) and thermal gravimetric analysis (TGA)

  17. Production of CO-rich Hydrogen Gas from Methane Dry Reforming over Co/CeO2 Catalyst

    Directory of Open Access Journals (Sweden)

    Bamidele V. Ayodele

    2016-08-01

    Full Text Available Production of CO-rich hydrogen gas from methane dry reforming was investigated over CeO2-supported Co catalyst. The catalyst was synthesized by wet impregnation and subsequently characterized by field emission scanning electron microscope (FESEM, energy dispersion X-ray spectroscopy (EDX, liquid N2 adsorption-desorption, X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR and thermogravimetric analysis (TGA for the structure, surface and thermal properties. The catalytic activity test of the Co/CeO2 was investigated between 923-1023 K under reaction conditions in a stainless steel fixed bed reactor. The composition of the products (CO2 and H2 from the methane dry reforming reaction was measured by gas chromatography (GC coupled with thermal conductivity detector (TCD. The effects of feed ratios and reaction temperatures were investigated on the catalytic activity toward product selectivity, yield, and syngas ratio. Significantly, the selectivity and yield of both H2 and CO increases with feed ratio and temperature. However, the catalyst shows higher activity towards CO selectivity. The highest H2 and CO selectivity of 19.56% and 20.95% respectively were obtained at 1023 K while the highest yield of 41.98% and 38.05% were recorded for H2 and CO under the same condition. Copyright © 2016 BCREC GROUP. All rights reserved Received: 21st January 2016; Revised: 23rd February 2016; Accepted: 23rd February 2016 How to Cite: Ayodele, B.V., Khan, M.R., Cheng, C. K. (2016. Production of CO-rich Hydrogen Gas from Methane Dry Reforming over Co/CeO2 Catalyst. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (2: 210-219 (doi:10.9767/bcrec.11.2.552.210-219 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.11.2.552.210-219

  18. Pulsed laser deposition of nanostructured Co-B-O thin films as efficient catalyst for hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Jadhav, H., E-mail: jadhav.hs2013@gmail.com [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Singh, A.K. [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Patel, N.; Fernandes, R.; Gupta, S.; Kothari, D.C. [Department of Physics and National Centre for Nanosciences & Nanotechnology, University of Mumbai, Vidyanagari, Santacruz (E), Mumbai 400098 (India); Miotello, A. [Dipartimento di Fisica, Università degli Studi di Trento, I-38123 Povo, Trento (Italy); Sinha, S. [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

    2016-11-30

    Highlights: • Pulsed laser deposition was used to deposit Co-B-O film nanocatalyst. • Co-B-O NPs are well separated, stable and immobilized on film surface. • Catalytic H{sub 2} production was studied by hydrolysis of Sodium Borohydride. • Four times higher H{sub 2} production rate was recorded for Co-B-O film than Co-B-O powder. • High particle density, polycrystalline nature and good stability against agglomeration of Co NPs. - Abstract: Nanoparticles assembled Co-B-O thin film catalysts were synthesized by pulsed laser deposition (PLD) technique for hydrolysis of Sodium Borohydride (SBH). Surface morphology of the deposited films was investigated using SEM and TEM, while compositional analysis was studied using XPS. Structural properties of Co-B-O films were examined using XRD and HRTEM. Laser process is able to produce well separated and immobilized Co-B-O NPs on the film surface which act as active centers leading to superior catalytic activity producing hydrogen at a significantly higher rate as compared to bulk powder. Co-B-O thin film catalyst produces hydrogen at a maximum rate of ∼4400 ml min{sup −1} g{sup −1} of catalyst, which is four times higher than powder catalyst. PLD parameters such as laser fluence and substrate-target distance were varied during deposition in order to understand the role of size and density of the immobilized Co-B-O NPs in the catalytic process. Films deposited at 3–5 cm substrate-target distance showed better performance than that deposited at 6 cm, mainly on account of the higher density of active Co-B-O NPs on the films surface. Features such as high particle density, polycrystalline nature of Co NPs and good stability against agglomeration mainly contribute towards the superior catalytic activity of Co-B-O films deposited by PLD.

  19. Hydrogen generation from bioethanol reforming : bench-scale unit performance with Cu/Nb2O5 catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Machado, N.R.C.F.; Rizzo, R.C.P.; Calsavara, V.; Takahashi, F.; Almeida, A.A.; Melo, F.R. de; Zschornack, M.A.; Bessani, A.N.; Rodrigues, R.M.O. [State University of Maringa, Maringa (Brazil). Dept. of Chemical Engineering Lab. of Catalysis; Schmal, M. [Cidade Universitaria, Rio de Janeiro (Brazil). Centro de Tecnologia, Graduate School and Research in Engineering Alberto Luiz Coimbra Institute; Cantao, M.P. [Institute of Technology for Development, Curitiba (Brazil). Dept. of Materials

    2003-07-01

    A series of experiments have been conducted to produce hydrogen from ethanol reforming. This paper presents the bench-scale study unit that uses a 5 per cent copper-niobium2oxygen5 (Cu/Nb2O5) catalyst previously selected in a micro reactor. X-ray diffraction analysis revealed that the catalyst contained copper oxide in an amorphous form and that the Nb2O5 was highly crystalline. The calcinated catalyst was analysed with X-ray photoelectron spectroscopy and showed that 35 per cent of total copper was on the surface as Cu{sup I} (55 per cent) and Cu{sup II} (45 per cent). The surface area was mainly comprised of meso and macro pores. There was a two-step reduction of Cu{sup II} to Cu at 245 and 306 degrees C, as shown by temperature programmed reduction, as well as a 6 per cent reduction of Nb2O5. An internal reactor with 16 grams (g) of catalyst pellets was contained in the reaction unit. To optimize hydrogen production, reaction temperature and feed rate were varied, and the major by-product was carbon dioxide. Reagents (water and ethanol) were fed into and vaporized in, an electric pre-heater in stoichiometric proportion. Mean conversion increased from 17 per cent to 35 per cent through an increase of reaction temperature from 300 to 400 degrees C. Minor by-products were detected in the form of ethene and ethyl ether. 9 refs., 3 tabs., 4 figs.

  20. Adsorption and Deactivation Characteristics of Cu/ZnO-Based Catalysts for Methanol Synthesis from Carbon Dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Natesakhawat, Sittichai; Ohodnicki, Paul R; Howard, Bret H; Lekse, Jonathan W; Baltrus, John P; Matranga, Christopher

    2013-07-09

    The adsorption and deactivation characteristics of coprecipitated Cu/ZnO-based catalysts were examined and correlated to their performance in methanol synthesis from CO₂ hydrogenation. The addition of Ga₂O₃ and Y₂O₃ promoters is shown to increase the Cu surface area and CO₂/H₂ adsorption capacities of the catalysts and enhance methanol synthesis activity. Infrared studies showed that CO₂ adsorbs spontaneously on these catalysts at room temperature as both monoand bi-dentate carbonate species. These weakly bound species desorb completely from the catalyst surface by 200 °C while other carbonate species persist up to 500 °C. Characterization using N₂O decomposition, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) with energy-dispersive X-ray spectroscopy (EDX) analysis clearly indicated that Cu sintering is the main cause of catalyst deactivation. Ga and Y promotion improves the catalyst stability by suppressing the agglomeration of Cu and ZnO particles under pretreatment and reaction conditions.

  1. Utilization of greenhouse gases through dry reforming: screening of nickel-based bimetallic catalysts and kinetic studies.

    Science.gov (United States)

    Fan, Mun-Sing; Abdullah, Ahmad Zuhairi; Bhatia, Subhash

    2011-11-18

    A series of bimetallic catalysts containing nickel supported over MgO-ZrO2 were tested for activity in the dry reforming of carbon dioxide. A nickel-cobalt bimetallic catalyst gave the best performance in terms of conversion and coke resistance from a range of Ni-X bimetallic catalysts, X=Ca, K, Ba, La, and Ce. The nitrogen-adsorption and hydrogen-chemisorption studies showed the Ni-Co bimetallic supported catalyst to have good surface area with high metal dispersion. This contributed to the high catalytic activity, in terms of conversion activity and stability of the catalyst, at an equimolar methane/carbon dioxide feed ratio. The kinetics of methane dry reforming are studied in a fixed-bed reactor over an Ni-Co bimetallic catalyst in the temperature range 700-800 °C by varying the partial pressures of CH4 and CO2. The experimental data were analyzed based on the proposed reaction mechanism using the Langmuir-Hinshelwood kinetic model. The activation energies for methane and carbon dioxide consumption were estimated at 52.9 and 48.1 kJ mol(-1), respectively. The lower value of CO2 activation energy compared to the activation energy of CH4 indicated a higher reaction rate of CO2, which owes to the strong basicity of nanocrystalline support, MgO-ZrO2.

  2. High-performance Platinum-free oxygen reduction reaction and hydrogen oxidation reaction catalyst in polymer electrolyte membrane fuel cell.

    Science.gov (United States)

    Chandran, Priji; Ghosh, Arpita; Ramaprabhu, Sundara

    2018-02-26

    The integration of polymer electrolyte membrane fuel cell (PEMFC) stack into vehicles necessitates the replacement of high-priced platinum (Pt)-based electrocatalyst, which contributes to about 45% of the cost of the stack. The implementation of high-performance and durable Pt metal-free catalyst for both oxygen reduction reaction (ORR) and hydrogen oxidation reaction (HOR) could significantly enable large-scale commercialization of fuel cell-powered vehicles. Towards this goal, a simple, scalable, single-step synthesis method was adopted to develop palladium-cobalt alloy supported on nitrogen-doped reduced graphene oxide (Pd 3 Co/NG) nanocomposite. Rotating ring-disk electrode (RRDE) studies for the electrochemical activity towards ORR indicates that ORR proceeds via nearly four-electron mechanism. Besides, the mass activity of Pd 3 Co/NG shows an enhancement of 1.6 times compared to that of Pd/NG. The full fuel cell measurements were carried out using Pd 3 Co/NG at the anode, cathode in conjunction with Pt/C and simultaneously at both anode and cathode. A maximum power density of 68 mW/cm 2 is accomplished from the simultaneous use of Pd 3 Co/NG as both anode and cathode electrocatalyst with individual loading of 0.5 mg/cm 2 at 60 °C without any backpressure. To the best of our knowledge, the present study is the first of its kind of a fully non-Pt based PEM full cell.

  3. Catalyst Deactivation 2001

    Energy Technology Data Exchange (ETDEWEB)

    Spivey, J.J. (ed.); Roberts, G.W. (ed.) [Department of Chemical Engineering, 2401 Stinson Avenue, Riddick Engineering Labs, NC State University, Box 7905, Raleigh, NC 27695 (United States); Davis, B.H. (ed.) [University of Kentucky, Centre for Applied Energy Research, 2540 Research Park Drive, Lexington, KY 40511-8433 (United States)

    2001-10-01

    Selected Papers: Maxted Award Lecture. Whisker carbon revisited (J.R. Rostrup-Nielsen, J Sehested). Carbon Deposition. Various forms of the carbonaceous deposit on the model cobalt catalyst studied in hydrogenation of ethylene (J. Lojewska). Hydrodechlorination of 1,2-dichloropropane over Pt-Cu/C catalysts: coke formation determined by a novel technique-TEOM (Weidung. Zhu et al.). Characterization of structure and combustion behavior of the coke formed on a hydroisomerization catalyst (Jin-an Wang et al.). The effects of pore structure on catalyst deactivation by coke formation (L.D.T. Camara et al.). Coke deactivation of acid sites on ZSM-5 zeolite (G.V. Echevsky et al.). Characterization of the Working Catalyst. Deactivation of a zirconia supported chromia aromatization catalyst investigated by in-situ H-D tracer experiments (H. Ehwald et al.). Deactivation/Regeneration in Environmental Processes. Study of the sintering of a DeNOx commercial catalyst (I. Nova et al.). Deactivation of chromium oxide catalyst for the removal of perchloroethylene (PCE) (Sung Dae Yim et al.). Deactivation/Regeneration in Industrial Processes. Deactivation of Pd-based combustion catalysts supported on modified alumina (P.O. Thevenin et al.). Selective acid-base poisoning on bifunctional alkylation reaction (A. Borgna et al.). Processes occurring during deactivation/regeneration of a vanadia/alumina catalyst under propane dehydrogenation conditions (S David Jackson et al.). Regeneration of supported palladium catalyst for selective hydrogenation of acetylene (L.O. Almanza, O.I. Martinez). Quinone mediated stabilization of a palladium catalyst for the synthesis of hydrogen peroxide from carbon monoxide, water and oxygen (D. Bianchi et al.). Metals on a novel USY zeolite after hydrothermal aging (Huiping Tian et al.). General Papers. Partial oxidation of toluene to benzaldehyde over vanadium antimonate catalysts doped with titanium: The influence (S. Larrondo et al.). Deactivation and

  4. Aqueous-Phase Reforming of Renewable Polyols for Production of Hydrogen using Platinum Catalysts

    NARCIS (Netherlands)

    Boga, D.A.

    2013-01-01

    Hydrogen has the potential to fuel the energy needs of a more sustainable society. As hydrogen is not found in nature in any appreciable quantities, this energy carrier needs to be produced from a primary energy source. Biomass can serve as a source for sustainable hydrogen production. In principle,

  5. Hydroformylation of Cyclohexene with Carbon Dioxide and Hydrogen Using Ruthenium Carbonyl Catalyst: Influence of Pressures of Gaseous Components

    Directory of Open Access Journals (Sweden)

    Masahiko Arai

    2007-08-01

    Full Text Available Hydroformylation of cyclohexene was studied with a catalyst system ofRu3(CO12 and LiCl using H2 and CO2 instead of CO in NMP. The influence of H2 andCO2 pressures on the total conversion and the product distribution was examined. It wasshown that increasing total pressure of H2 and CO2 promoted the reverse water gas shiftreaction and increased the yield of cyclohexanecarboxaldehyde. Its hydrogenation tocyclohexanemethanol was promoted with increasing H2 pressure but suppressed withincreasing CO2 pressure. Cyclohexane was also formed along with those products and thisdirect hydrogenation was suppressed with increasing CO2 pressure. The roles of CO2 as apromoter as well as a reactant were further examined by phase behavior observations andhigh pressure FTIR measurements.

  6. Probing Transition-Metal Silicides as PGM-Free Catalysts for Hydrogen Oxidation and Evolution in Acidic Medium

    Science.gov (United States)

    Mittermeier, Thomas; Madkikar, Pankaj; Wang, Xiaodong; Gasteiger, Hubert A.; Piana, Michele

    2017-01-01

    In this experimental study, we investigate various transition-metal silicides as platinum-group-metal-(PGM)-free electrocatalysts for the hydrogen oxidation reaction (HOR), and for the hydrogen evolution reaction (HER) in acidic environment for the first time. Using cyclic voltammetry in 0.1 M HClO4, we first demonstrate that the tested materials exhibit sufficient stability against dissolution in the relevant potential window. Further, we determine the HOR and HER activities for Mo, W, Ta, Ni and Mo-Ni silicides in rotating disk electrode experiments. In conclusion, for the HOR only Ni2Si shows limited activity, and the HER activity of the investigated silicides is considerably lower compared to other PGM-free HER catalysts reported in the literature. PMID:28773022

  7. Pd/C Synthesized with Citric Acid: An Efficient Catalyst for Hydrogen Generation from Formic Acid/Sodium Formate

    Science.gov (United States)

    Wang, Zhi-Li; Yan, Jun-Min; Wang, Hong-Li; Ping, Yun; Jiang, Qing

    2012-01-01

    A highly efficient hydrogen generation from formic acid/sodium formate aqueous solution catalyzed by in situ synthesized Pd/C with citric acid has been successfully achieved at room temperature. Interestingly, the presence of citric acid during the formation and growth of the Pd nanoparticles on carbon can drastically enhance the catalytic property of the resulted Pd/C, on which the conversion and turnover frequency for decomposition of formic acid/sodium formate system can reach the highest values ever reported of 85% within 160 min and 64 mol H2 mol−1 catalyst h−1, respectively, at room temperature. The present simple, low cost, but highly efficient CO-free hydrogen generation system at room temperature is believed to greatly promote the practical application of formic acid system on fuel cells. PMID:22953041

  8. Pd/C Synthesized with Citric Acid: An Efficient Catalyst for Hydrogen Generation from Formic Acid/Sodium Formate

    Science.gov (United States)

    Wang, Zhi-Li; Yan, Jun-Min; Wang, Hong-Li; Ping, Yun; Jiang, Qing

    2012-08-01

    A highly efficient hydrogen generation from formic acid/sodium formate aqueous solution catalyzed by in situ synthesized Pd/C with citric acid has been successfully achieved at room temperature. Interestingly, the presence of citric acid during the formation and growth of the Pd nanoparticles on carbon can drastically enhance the catalytic property of the resulted Pd/C, on which the conversion and turnover frequency for decomposition of formic acid/sodium formate system can reach the highest values ever reported of 85% within 160 min and 64 mol H2 mol-1 catalyst h-1, respectively, at room temperature. The present simple, low cost, but highly efficient CO-free hydrogen generation system at room temperature is believed to greatly promote the practical application of formic acid system on fuel cells.

  9. Down Select Report of Chemical Hydrogen Storage Materials, Catalysts, and Spent Fuel Regeneration Processes

    Energy Technology Data Exchange (ETDEWEB)

    Ott, Kevin; Linehan, Sue; Lipiecki, Frank; Aardahl, Christopher L.

    2008-08-24

    The DOE Hydrogen Storage Program is focused on identifying and developing viable hydrogen storage systems for onboard vehicular applications. The program funds exploratory research directed at identifying new materials and concepts for storage of hydrogen having high gravimetric and volumetric capacities that have the potential to meet long term technical targets for onboard storage. Approaches currently being examined are reversible metal hydride storage materials, reversible hydrogen sorption systems, and chemical hydrogen storage systems. The latter approach concerns materials that release hydrogen in endothermic or exothermic chemical bond-breaking processes. To regenerate the spent fuels arising from hydrogen release from such materials, chemical processes must be employed. These chemical regeneration processes are envisioned to occur offboard the vehicle.

  10. A Highly Efficient and Self-Stabilizing Metallic-Glass Catalyst for Electrochemical Hydrogen Generation.

    Science.gov (United States)

    Hu, Yuan Chao; Wang, Yi Zhi; Su, Rui; Cao, Cheng Rong; Li, Fan; Sun, Chun Wen; Yang, Yong; Guan, Peng Fei; Ding, Da Wei; Wang, Zhong Lin; Wang, Wei Hua

    2016-12-01

    A multicomponent metallic glass (MG) with highly efficient and anomalous durability for catalyzing water splitting is reported. The outstanding performance of the MG catalyst contributed by self-optimized active sites originates from the intrinsic chemical heterogeneity and selective dealloying on the disordered surface; thus, a new mechanism for improving the durability of catalysts is uncovered. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Effects of Cu over Pd based catalysts supported on silica or niobia

    Directory of Open Access Journals (Sweden)

    Roma M.N.S.C.

    2000-01-01

    Full Text Available Palladium and palladium-copper catalysts supported on silica and niobia were characterized by H2 chemisorption and H2-O2 titration. Systems over silica were also analyzed by transmission electron microscopy and EXAFS. The metallic dispersion decreased from 20% to 7% when the content of Pd was increased from 0.5wt.-% to 3wt.-% in monometallic catalysts. The addition of 3 wt.-% Cu to obtain Pd-Cu catalysts caused a remarkable capacity loss of hydrogen chemisorption. TPR analysis suggested an interaction between the two metals and EXAFS characterization of the catalyst supported on silica confirmed the formation of Pd-Cu alloy. Pd/Nb2O5 catalysts showed turnover numbers higher than those obtained with the Pd/SiO2 systems in the cyclohexane dehydrogenation. However, the bimetallic catalysts showed very low turnover numbers.

  12. Xerogel-sequestered silanated organochalcogenide catalysts for bromination with hydrogen peroxide and sodium bromide.

    Science.gov (United States)

    Gatley, Caitlyn M; Muller, Lisa M; Lang, Meredith A; Alberto, Eduardo E; Detty, Michael R

    2015-05-26

    While H2O2 is a powerful oxidant, decomposing into environmentally benign H2O and O2, a catalyst is often required for reactions with H2O2 to proceed at synthetically useful rates. Organotellurium and organoselenium compounds catalyze the oxidation of halide salts to hypohalous acids using H2O2. When sequestered into xerogel monoliths, the xerogel-chalcogenide combinations have demonstrated increased catalytic activity relative to the organochalcogen compound alone in solution for the oxidation of halide salts to hypohalous acids with H2O2. Diorganotellurides, diorganoselenides, and diorganodiselenides bearing triethoxysilane functionalities were sequestered into xerogel monoliths and their catalytic activity and longevity were investigated. The longevity of the catalyst-xerogel combinations was examined by isolating and recycling the catalyst-xerogel combination. It was found tellurium-containing catalyst 3 and selenium-containing catalyst 8 maintained their catalytic activity through three recycling trials and adding electron-donating substituents to catalyst 3 also increased the catalytic rate. The presence of organotellurium and organoselenium groups in the +4 oxidation state was determined by X-ray photoelectron spectroscopy.

  13. Xerogel-Sequestered Silanated Organochalcogenide Catalysts for Bromination with Hydrogen Peroxide and Sodium Bromide

    Directory of Open Access Journals (Sweden)

    Caitlyn M. Gatley

    2015-05-01

    Full Text Available While H2O2 is a powerful oxidant, decomposing into environmentally benign H2O and O2, a catalyst is often required for reactions with H2O2 to proceed at synthetically useful rates. Organotellurium and organoselenium compounds catalyze the oxidation of halide salts to hypohalous acids using H2O2. When sequestered into xerogel monoliths, the xerogel-chalcogenide combinations have demonstrated increased catalytic activity relative to the organochalcogen compound alone in solution for the oxidation of halide salts to hypohalous acids with H2O2. Diorganotellurides, diorganoselenides, and diorganodiselenides bearing triethoxysilane functionalities were sequestered into xerogel monoliths and their catalytic activity and longevity were investigated. The longevity of the catalyst-xerogel combinations was examined by isolating and recycling the catalyst-xerogel combination. It was found tellurium-containing catalyst 3 and selenium-containing catalyst 8 maintained their catalytic activity through three recycling trials and adding electron-donating substituents to catalyst 3 also increased the catalytic rate. The presence of organotellurium and organoselenium groups in the +4 oxidation state was determined by X-ray photoelectron spectroscopy.

  14. Stabilization of Hydrogen Production via Methanol Steam Reforming in Microreactor by Al2O3 Nano-Film Enhanced Catalyst Adhesion.

    Science.gov (United States)

    Jeong, Heondo; Na, Jeong-Geol; Jang, Min Su; Ko, Chang Hyun

    2016-05-01

    In hydrogen production by methanol steam reforming reaction with microchannel reactor, Al2O3 thin film formed by atomic layer deposition (ALD) was introduced on the surface of microchannel reactor prior to the coating of catalyst particles. Methanol conversion rate and hydrogen production rate, increased in the presence of Al2O3 thin film. Over-view and cross-sectional scanning electron microscopy study showed that the adhesion between catalyst particles and the surface of microchannel reactor enhanced due to the presence of Al2O3 thin film. The improvement of hydrogen production rate inside the channels of microreactor mainly came from the stable fixation of catalyst particles on the surface of microchannels.

  15. Mg-based compounds for hydrogen and energy storage

    NARCIS (Netherlands)

    Crivello, J. -C.; Denys, R. V.; Dornheim, M.; Felderhoff, M.; Grant, D. M.; Huot, J.; Jensen, T. R.; de Jongh, P.; Latroche, M.; Walker, G. S.; Webb, C. J.; Yartys, V. A.

    Magnesium-based alloys attract significant interest as cost-efficient hydrogen storage materials allowing the combination of high gravimetric storage capacity of hydrogen with fast rates of hydrogen uptake and release and pronounced destabilization of the metal–hydrogen bonding in comparison with

  16. Catalytic Oxidation of Phenol over Zeolite Based Cu/Y-5 Catalyst: Part 1: Catalyst Preparation and Characterization

    Directory of Open Access Journals (Sweden)

    K. Maduna Valkaj

    2015-01-01

    Full Text Available The necessity to remove organic pollutants from the industrial wastewater streams has forced the development of new technologies that can produce better results in terms of pollutant removal and process efficiency in combination with low investment and operating costs. One of the new emerging processes with a potential to fulfil these demands is catalytic wet peroxide oxidation, commonly known as the CWPO process. The oxidative effect of the hydrogen peroxide is intensified by the addition of a heterogeneous catalyst that can reduce the operating conditions to atmospheric pressure and temperatures below 383 K. Zeolites, among others, are especially appealing as catalysts for selective oxidation processes due to their unique characteristics such as shape selectivity, thermal and chemical stability, and benign effect on nature and the living world. In this work, catalytic activity, selectivity and stability of Cu/Y-5 zeolite in phenol oxidation with hydrogen peroxide was examined. Catalyst samples were prepared by ion exchange method of the protonic form of commercial zeolite. The catalysts were characterized with powder X-ray diffraction (XRD, scanning electron microscopy (SEM, and AAS elemental analysis, while the adsorption techniques were used for the measurement of the specific surface area. The catalytic tests were carried out in a stainless steel Parr reactor in batch operation mode at the atmospheric pressure and in the temperature range from 323 to 353 K. The catalyst was prepared in powdered form and the mass fraction of the active metal component on the zeolite was 3.46 %. The initial concentration of phenol solution was equal to 0.01 mol dm−3 and the concentration of hydrogen peroxide ranged from 0.01 to 0.10 mol dm−3. The obtained experimental data was tested to a proposed kinetic model for phenol oxidation r = k1 cF cVP and hydrogen peroxide decomposition rHP = k2 cHP. The kinetic parameters were estimated using the Nelder

  17. Hydrogen Research for Spaceport and Space-Based Applications: Hydrogen Production, Storage, and Transport. Part 3

    Science.gov (United States)

    Anderson, Tim; Balaban, Canan

    2008-01-01

    The activities presented are a broad based approach to advancing key hydrogen related technologies in areas such as fuel cells, hydrogen production, and distributed sensors for hydrogen-leak detection, laser instrumentation for hydrogen-leak detection, and cryogenic transport and storage. Presented are the results from research projects, education and outreach activities, system and trade studies. The work will aid in advancing the state-of-the-art for several critical technologies related to the implementation of a hydrogen infrastructure. Activities conducted are relevant to a number of propulsion and power systems for terrestrial, aeronautics and aerospace applications. Hydrogen storage and in-space hydrogen transport research focused on developing and verifying design concepts for efficient, safe, lightweight liquid hydrogen cryogenic storage systems. Research into hydrogen production had a specific goal of further advancing proton conducting membrane technology in the laboratory at a larger scale. System and process trade studies evaluated the proton conducting membrane technology, specifically, scale-up issues.

  18. Glucose reactions with acid and base catalysts in hot compressed water at 473 K.

    Science.gov (United States)

    Watanabe, Masaru; Aizawa, Yuichi; Iida, Toru; Aida, Taku M; Levy, Caroline; Sue, Kiwamu; Inomata, Hiroshi

    2005-09-05

    The effects of the homogeneous catalysts (H(2)SO(4) and NaOH) and heterogeneous catalysts (TiO(2) and ZrO(2)) on glucose reactions were examined in hot compressed water (473 K) by a batch-type reactor. From the homogeneous catalyst studies, we confirmed that the acid catalyst promoted dehydration, while isomerization of glucose to fructose was catalyzed by alkali. Anatase TiO(2) was found to act as an acid catalyst to promote formation of 5-hydroxymethylfuraldehyde (HMF). Zirconia (ZrO(2)) was a base catalyst to promote the isomerization of glucose. The effects of the additives were also confirmed through fructose reactions.

  19. Kjel-Foss automatic analysis using an antimony-based catalyst: collaborative study.

    Science.gov (United States)

    Bjarnø, O C

    1980-05-01

    Collaborators in 7 Kjel-Foss laboratories and 1 manual Kjeldahl laboratory performed protein determinations on fishmeal: 10 with traditional mercury catalyst and 10 with a new antimony-based catalyst. Repeatability, interlaboratory variation, and variation vs. manual Kjeldahl were equal to or better with the new catalyst than with the mercury catalyst. In addition, 48 different products were analyzed: 5-10 determinations were made on each product with the mercury catalyst and 5-10 were made with the new catalyst. After the Kjel-Foss procedure was modified slightly with higher acid settings, the differences in recovery and repeatability of the 2 procedures were not more than +/- 1%.

  20. Tungsten based catalysts for selective deoxygenation

    NARCIS (Netherlands)

    Gosselink, R.W.|info:eu-repo/dai/nl/326164081; Stellwagen, D.R.; Bitter, J.H.|info:eu-repo/dai/nl/160581435

    2013-01-01

    Over the past decades, impending oil shortages combined with petroleum market instability have prompted a search for a new source of both transportation fuels and bulk chemicals. Renewable bio-based feedstocks such as sugars, grains, and seeds are assumed to be capable of contributing to a

  1. Pressure Drop Experiments on a Flow Channel Filled with Catalysts for Nuclear Hydrogen Production System

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sungdeok; Kim, C. S.; Kim, M. H.; Kim, Y. W. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Seo, D. U.; Park, G. C. [Seoul National Univ., Seoul (Korea, Republic of)

    2014-05-15

    The Korea Atomic Energy Research Institute (KAERI) has developed a hybrid-design decomposer to withstand severe operating conditions. Hong and Seo have been studying a two-dimensional numerical analysis for a catalyst channel line-up with a 3mm ball shaped catalyst. They compared their CFD results to many widespread correlations developed for porous media such as those by Carman, Ergun, and Zhavoronkov as well as Susskind and Becker and Reichelt including a pebble-bed nuclear reactor design correlation. They concluded that the validation should be accomplished by the experiments for a catalyst channel simulating the channel of the PHE. In this paper, we discuss the pressure drop experiments on a flow channel filled with ball shaped catalysts. The test section simulates a single channel of the PHE secondary side plate-fin channel. The experimental results compared well with the known pressure drop correlations and a numerical analysis, respectively. We discussed an experimental validation of a pressure drop correlations and 2D CFD analysis on a flow channel filled with catalysts in the channel. The results of the pressure drop measurements are compared with the results obtained using well-known empirical correlations and 2D CFD analysis. From the comparison results, the validity of all the correlations and 2D numerical analysis is not satisfactory. There are two kind of reasons are presumed. While the general packed channel has radially infinite and complete circular cross section, the catalyst channel has radially finite with a very narrow width and irregular wavy cross section. Another reason is presumed to be because the inordinate large void fraction in the catalyst channel which is beyond the application range on void fraction in the empirical correlations.

  2. Hydrogen-based uninterruptible power supply

    Energy Technology Data Exchange (ETDEWEB)

    Varkaraki, E.; Lymberopoulos, N.; Zoulias, E. [Center for Renewable Energy Sources, RES and Hydrogen Technologies, 19th km. Marathonos Av., 19009 Pikermi (Greece); Guichardot, D. [CReeD - (Vivendi Environnement), 291 Av. Dreyfus Ducas, 78520 Limay (France); Poli, G. [Technicatome, Cadarache BP9, 13115 St. Paul lez Durance (France)

    2007-07-15

    An uninterruptible power supply (UPS) based on hydrogen technologies has been designed, manufactured and tested. The system consists of a proton exchange membrane fuel cell running on hydrogen and oxygen, a gas storage section and a water electrolyser for hydrogen and oxygen production. The UPS is of fail-safe design, completely silent and very reliable, thanks to the complete absence of moving parts. The prototype has an output of 5 kW for a maximum period of 5 h. A 3 kW advanced alkaline electrolyser produces 0.6Nm{sup 3}/h hydrogen and 0.3Nm{sup 3}/h oxygen at 1.5 MPa, which are stored in metal hydride tanks of 21Nm{sup 3}H{sub 2} capacity and a cylinder stack, respectively. Upon grid power interruption, the fuel cell takes up the load, with the help of a battery during the first minutes of operation. The results of the operation of this prototype are presented and discussed. (author)

  3. Preparation and characterization of Ni based on natural zeolite catalyst for citronellol conversion to 3,7-Dimethyl-1-Octanol

    Science.gov (United States)

    Sudiyarmanto, Hidayati, Luthfiana N.; Kristiani, Anis; Ghaisani, Almira; Sukandar, Dede; Adilina, Indri B.; Tursiloadi, Silvester

    2017-11-01

    Citronella oil is a kind of essential oil that contains three main components, namely citronellal, citronellol, and geraniol. The high demand of citronellal and geraniol derivative prompted scientists to develop methods which are stereo-selective synthesis. A hydrogenation reaction using heterogeneous catalyst is one way of synthesis of citronella oil derivatives. In this research, synthesis of citronellol oil derivatives using Ni based on natural zeolite (Ni/ZAB) catalyst which is expected to produce the compound of 3,7-dimethyl-1-octanol. The catalyst was prepared by supporting Ni on natural zeolite by impregnation method. The physical and chemical properties of Ni/ZAB catalyst have been characterized by TGA, BET, XRD and FTIR instrumentations. Variation of pressure and temperature reactions were conducted to determine the optimum conditions for the hydrogenation of citronellol. The products from this reaction were analyzed using GC-MS instrumentation. The yield and selectivity of 3,7-dimethyl-1-octanol compound were achieved with optimum conditions at 200°C and 20 bar during 3 hours which produced around 51.97% and 47.81% respectively.

  4. Room-temperature CO Thermoelectric Gas Sensor based on Au/Co3O4 Catalyst Tablet

    Science.gov (United States)

    Sun, L.; Luan, W. L.; Wang, T. C.; Su, W. X.; Zhang, L. X.

    2017-02-01

    A carbon monoxide (CO) thermoelectric (TE) gas sensor was fabricated by affixing a Au/Co3O4 catalyst tablet on a TE film layer. The Au/Co3O4 catalyst tablet was prepared by a co-precipitation and tablet compression method and its possible catalytic mechanism was discussed by means of x-ray diffraction, field emission scanning electron microscopy, high resolution transmission electron microscopy, x-ray photoelectron spectroscopy, temperature-programmed reduction of hydrogen, Fourier transform infrared spectroscopy and Brunauer-Emmett-Teller analysis. The optimal catalyst, with a Au content of 10 wt%, was obtained at a calcination temperature between 200 and 300 °C. The small size of the Au nanoparticles, high specific surface, the existence of Co3+ and water-derived species contributed to high catalytic activity. Based on the optimal Au/Co3O4 catalyst tablet, the CO TE gas sensor worked at room temperature and showed a response voltage signal (ΔV) of 23 mV, high selectivity among hydrogen and methane, high stability, and a fast response time of 106 s for 30 000 ppm CO/air. In addition, a CO concentration in the range of 5000-30 000 ppm could obviously be detected and exhibited a linear relationship with ΔV. The CO TE gas sensor provides a promising option for the detection of CO gas at room temperature.

  5. Selective hydrogen production from methanol with a defined iron pincer catalyst under mild conditions.

    Science.gov (United States)

    Alberico, Elisabetta; Sponholz, Peter; Cordes, Christoph; Nielsen, Martin; Drexler, Hans-Joachim; Baumann, Wolfgang; Junge, Henrik; Beller, Matthias

    2013-12-23

    Molecularly well-defined iron pincer complexes promote the aqueous-phase reforming of methanol to carbon dioxide and hydrogen, which is of interest in the context of a methanol and hydrogen economy. For the first time, the use of earth-abundant iron complexes under mild conditions for efficient hydrogen generation from alcohols is demonstrated. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Hydrothermal synthesis and characterization of zirconia based catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Caillot, T., E-mail: Thierry.caillot@ircelyon.univ-lyon1.fr; Salama, Z.; Chanut, N.; Cadete Santos Aires, F.J.; Bennici, S.; Auroux, A.

    2013-07-15

    In this work, three equimolar mixed oxides ZrO{sub 2}/CeO{sub 2}, ZrO{sub 2}/TiO{sub 2}, ZrO{sub 2}/La{sub 2}O{sub 3} and a reference ZrO{sub 2} have been synthesized by hydrothermal method. The structural and surface properties of these materials have been fully characterized by X-ray diffraction, transmission electron microscopy, surface area measurement, chemical analysis, XPS, infrared spectroscopy after adsorption of pyridine and adsorption microcalorimetry of NH{sub 3} and SO{sub 2} probe molecules. All investigated mixed oxides are amphoteric and possess redox centers on their surface. Moreover, hydrothermal synthesis leads to catalysts with higher surface area and with better acid–base properties than classical coprecipitation method. Both Lewis and Brønsted acid sites are present on the surface of the mixed oxides. Compared to the other samples, the ZrO{sub 2}/TiO{sub 2} material appears to be the best candidate for further application in acid–base catalysis. - Graphical abstract: Mesoporous amorphous phase with a high surface area of titania zirconia mixed oxide obtained by hydrothermal preparation. - Highlights: • Three zirconia based catalysts and a reference were prepared by hydrothermal synthesis. • Mixed oxides present larger surface areas than the reference ZrO{sub 2}. • ZrO{sub 2}/TiO{sub 2} catalyst presents a mesoporous structure with high surface area. • ZrO{sub 2}/TiO{sub 2} catalyst presents simultaneously strong acidic and basic properties.

  7. Hydrogen Production by Steam Reforming of Ethanol over Nickel Catalysts Supported on Sol Gel Made Alumina: Influence of Calcination Temperature on Supports.

    Science.gov (United States)

    Yaakob, Zahira; Bshish, Ahmed; Ebshish, Ali; Tasirin, Siti Masrinda; Alhasan, Fatah H

    2013-05-30

    Selecting a proper support in the catalyst system plays an important role in hydrogen production via ethanol steam reforming. In this study, sol gel made alumina supports prepared for nickel (Ni) catalysts were calcined at different temperatures. A series of (Ni/AlS.G.) catalysts were synthesized by an impregnation procedure. The influence of varying the calcination temperature of the sol gel made supports on catalyst activity was tested in ethanol reforming reaction. The characteristics of the sol gel alumina supports and Ni catalysts were affected by the calcination temperature of the supports. The structure of the sol gel made alumina supports was transformed in the order of γ → (γ + θ) → θ-alumina as the calcination temperature of the supports increased from 600 °C to 1000 °C. Both hydrogen yield and ethanol conversion presented a volcano-shaped behavior with maximum values of 4.3 mol/mol ethanol fed and 99.5%, respectively. The optimum values were exhibited over Ni/AlS.G800 (Ni catalyst supported on sol gel made alumina calcined at 800 °C). The high performance of the Ni/AlS.G800 catalyst may be attributed to the strong interaction of Ni species and sol gel made alumina which lead to high nickel dispersion and small particle size.

  8. Gas-phase hydrogenation influence on defect behavior in titanium-based hydrogen-storage material

    Directory of Open Access Journals (Sweden)

    Roman S. Laptev

    2017-02-01

    Full Text Available Titanium and its alloys are promising materials for hydrogen storage. However, hydrogen penetration accompanies the exploitation of hydrogen storage alloys. In particular, hydrogen penetration and accumulation in titanium alloys changes their mechanical properties. Therefore, the research works of such materials are mainly focused on improving the reversibility of hydrogen absorption-liberation processes, increasing the thermodynamic characteristics of the alloys, and augmenting their hydrogen storage capacity. In the process of hydrogenation-dehydrogenation, the formed defects both significantly reduce hydrogen storage capacity and can also be used to create effective traps for hydrogen. Therefore, the investigation of hydrogen interaction with structural defects in titanium and its alloys is very important. The present work, the hydrogen-induced formation of defects in the alloys of commercially pure titanium under temperature gas-phase hydrogenation (873 K has studied by positron lifetime spectroscopy and Doppler broadening spectroscopy. Based on the evolution of positron annihilation parameters τf, τd, their corresponding intensities If, Id and relative changes of parameters S/S0 and W/W0, the peculiarities of hydrogen interaction with titanium lattice defects were investigated in a wide range of hydrogen concentrations from 0.8at% to 32.0at%.

  9. Multifunctional Pd/Ni-Co catalyst for hydrogen production by chemical looping coupled with steam reforming of acetic acid.

    Science.gov (United States)

    Fermoso, Javier; Gil, María V; Rubiera, Fernando; Chen, De

    2014-11-01

    High yield of high-purity H2 from acetic acid, a model compound of bio-oil obtained from the fast pyrolysis of biomass, was produced by sorption-enhanced steam reforming (SESR). An oxygen carrier was introduced into a chemical loop (CL) coupled to the cyclical SESR process to supply heat in situ for the endothermic sorbent regeneration to increase the energy efficiency of the process. A new multifunctional 1 %Pd/20 %Ni-20 %Co catalyst was developed for use both as oxygen carrier in the CL and as reforming catalyst in the SESR whereas a CaO-based material was used as CO2 sorbent. In the sorbent-air regeneration step, the Ni-Co atoms in the catalyst undergo strong exothermic oxidation reactions that provide heat for the CaO decarbonation. The addition of Pd to the Ni-Co catalyst makes the catalyst active throughout the whole SESR-CL cycle. Pd significantly promotes the reduction of Ni-Co oxides to metallic Ni-Co during the reforming stage, which avoids the need for a reduction step after regeneration. H2 yield above 90 % and H2 purity above 99.2 vol % were obtained. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Pt-Pd bimetallic nanoparticles on MWCNTs: catalyst for hydrogen peroxide electrosynthesis

    Science.gov (United States)

    Félix-Navarro, R. M.; Beltrán-Gastélum, M.; Salazar-Gastélum, M. I.; Silva-Carrillo, C.; Reynoso-Soto, E. A.; Pérez-Sicairos, S.; Lin, S. W.; Paraguay-Delgado, F.; Alonso-Núñez, G.

    2013-08-01

    Bimetallic nanoparticles of Pt-Pd were deposited by the microemulsion method on a multiwall carbon nanotube (MWCNTs) to obtain a Pt-Pd/MWCNTs for electrocatalytic reduction of O2 to H2O2. The activity and selectivity of the catalyst was determined qualitatively by the rotating disk electrode method in acidic medium. The catalyst was spray-coated onto a reticulated vitreous carbon substrate and quantitatively was tested in bulk electrolysis for 20 min under potentiostatic conditions (0.5 V vs Ag/AgCl) in a 0.5 M H2SO4 electrolyte using dissolved O2. The bulk electrolysis experiments show that the Pt-Pd/MWCNTs catalyst is more efficient for H2O2 electrogeneration than a MWCNTs catalyst. Nitrobenzene degradation by electrogenerated H2O2 alone and Electro-Fenton process were also tested. Our results show that both processes decompose nitrobenzene, but the Electro-Fenton process does it more efficiently. The prepared nanoparticulated catalyst shows a great potential in environmental applications.

  11. Pt-Pd bimetallic nanoparticles on MWCNTs: catalyst for hydrogen peroxide electrosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Felix-Navarro, R. M., E-mail: moi6salazar@hotmail.com; Beltran-Gastelum, M.; Salazar-Gastelum, M. I.; Silva-Carrillo, C.; Reynoso-Soto, E. A.; Perez-Sicairos, S.; Lin, S. W. [Centro de Graduados e Investigacion, Instituto Tecnologico de Tijuana (Mexico); Paraguay-Delgado, F. [Centro de Investigacion en Materiales Avanzados (Mexico); Alonso-Nunez, G. [Centro de Nanociencias y Nanotecnologia (Mexico)

    2013-08-15

    Bimetallic nanoparticles of Pt-Pd were deposited by the microemulsion method on a multiwall carbon nanotube (MWCNTs) to obtain a Pt-Pd/MWCNTs for electrocatalytic reduction of O{sub 2} to H{sub 2}O{sub 2}. The activity and selectivity of the catalyst was determined qualitatively by the rotating disk electrode method in acidic medium. The catalyst was spray-coated onto a reticulated vitreous carbon substrate and quantitatively was tested in bulk electrolysis for 20 min under potentiostatic conditions (0.5 V vs Ag/AgCl) in a 0.5 M H{sub 2}SO{sub 4} electrolyte using dissolved O{sub 2}. The bulk electrolysis experiments show that the Pt-Pd/MWCNTs catalyst is more efficient for H{sub 2}O{sub 2} electrogeneration than a MWCNTs catalyst. Nitrobenzene degradation by electrogenerated H{sub 2}O{sub 2} alone and Electro-Fenton process were also tested. Our results show that both processes decompose nitrobenzene, but the Electro-Fenton process does it more efficiently. The prepared nanoparticulated catalyst shows a great potential in environmental applications.

  12. Catalyst in Basic Oleochemicals

    Directory of Open Access Journals (Sweden)

    Eva Suyenty

    2007-10-01

    Full Text Available Currently Indonesia is the world largest palm oil producer with production volume reaching 16 million tones per annum. The high crude oil and ethylene prices in the last 3 – 4 years contribute to the healthy demand growth for basic oleochemicals: fatty acids and fatty alcohols. Oleochemicals are starting to replace crude oil derived products in various applications. As widely practiced in petrochemical industry, catalyst plays a very important role in the production of basic oleochemicals. Catalytic reactions are abound in the production of oleochemicals: Nickel based catalysts are used in the hydrogenation of unsaturated fatty acids; sodium methylate catalyst in the transesterification of triglycerides; sulfonic based polystyrene resin catalyst in esterification of fatty acids; and copper chromite/copper zinc catalyst in the high pressure hydrogenation of methyl esters or fatty acids to produce fatty alcohols. To maintain long catalyst life, it is crucial to ensure the absence of catalyst poisons and inhibitors in the feed. The preparation methods of nickel and copper chromite catalysts are as follows: precipitation, filtration, drying, and calcinations. Sodium methylate is derived from direct reaction of sodium metal and methanol under inert gas. The sulfonic based polystyrene resin is derived from sulfonation of polystyrene crosslinked with di-vinyl-benzene. © 2007 BCREC UNDIP. All rights reserved.[Presented at Symposium and Congress of MKICS 2007, 18-19 April 2007, Semarang, Indonesia][How to Cite: E. Suyenty, H. Sentosa, M. Agustine, S. Anwar, A. Lie, E. Sutanto. (2007. Catalyst in Basic Oleochemicals. Bulletin of Chemical Reaction Engineering and Catalysis, 2 (2-3: 22-31.  doi:10.9767/bcrec.2.2-3.6.22-31][How to Link/DOI: http://dx.doi.org/10.9767/bcrec.2.2-3.6.22-31 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/6

  13. Hydrogen production by ethanol partial oxidation over nano-iron oxide catalysts produced by chemical vapour synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Wael Ahmed Abou Taleb Sayed

    2011-01-13

    stability was reported for a reaction time of 10 hours. The results showed that the reaction route, the product distribution and hydrogen selectivity strongly depend on the iron oxide phase. The {alpha}-Fe{sub 2}O{sub 3} phase showed high hydrogen selectivity with the highest stability. Over {alpha}-Fe{sub 2}O{sub 3}/SiC supported catalysts acetaldehyde, water and CO{sub 2} were the main products. The product distributions strongly depended on the catalyst iron content. With increasing sample iron content, more CO{sub 2} and water was produced. The catalyst with an iron content of 1.9% showed the highest acetaldehyde yield. This is attributed to the low iron oxide content at active sites which lead to a dehydrogenation of ethanol to acetaldehyde. In contrast, at higher iron content more active sites were provided hence the acetaldehyde re-adsorbed and further oxidised to CO{sub 2}. All supported catalysts showed a good stability for 10 hours. In this time, the ethanol conversion was decreased by 9% with constant acetaldehyde yield. These results provide evidence that the reaction occurs over the iron oxide surface and iron oxide-support interface but not over the SiC particles. These results were supported by carrying out the ethanol oxidation over pure {alpha}-Fe{sub 2}O{sub 3} nanoparticles with different surface areas. Those surface areas were chosen depending on the surface areas measured for the pure {alpha}-Fe{sub 2}O{sub 3} and surface area calculated for iron oxide in the supported samples. The investigation showed that with a large catalyst surface areas hydrogen with a high selectivity may be produced, whereas with a small surface area only acetaldehyde, water and CO{sub 2} can be produced. The characterisation of the used catalyst showed a small variation of the iron oxide particle size and large surface area. This proved that the SiC support avoids a hot spot formation and prevents iron oxide particles from being sintered. (orig.)

  14. Selective Catalytic Hydrogenation of Arenols by a Well-Defined Complex of Ruthenium and Phosphorus–Nitrogen PN3–Pincer Ligand Containing a Phenanthroline Backbone

    KAUST Repository

    Li, Huaifeng

    2017-05-30

    Selective catalytic hydrogenation of aromatic compounds is extremely challenging using transition-metal catalysts. Hydrogenation of arenols to substituted tetrahydronaphthols or cyclohexanols has been reported only with heterogeneous catalysts. Herein, we demonstrate the selective hydrogenation of arenols to the corresponding tetrahydronaphthols or cyclohexanols catalyzed by a phenanthroline-based PN3-ruthenium pincer catalyst.

  15. Kinetics of CO2 Hydrogenation to Hydrocarbons over Iron-Silica Catalysts.

    Science.gov (United States)

    Owen, Rhodri E; Mattia, Davide; Plucinski, Pawel; Jones, Matthew D

    2017-11-17

    The conversion of CO2 to hydrocarbons is increasingly seen as a potential alternative source of fuel and chemicals, while at the same time contributing to addressing global warming effects. An understanding of kinetics and mass transfer limitations is vital to both optimise catalyst performance and to scale up the whole process. In this work we report on a systematic investigation of the influence of the different process parameters, including pore size, catalyst support particle diameter, reaction temperature, pressure and reactant flow rate on conversion and selectivity of iron nanoparticle -silica catalysts. The results provided on activation energy and mass transfer limitations represent the basis to fully design a reactor system for the effective catalytic conversion of CO2 to hydrocarbons. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Benefits of mesopores in nanocristalline Pd/SnO2 catalysts for nitrate hydrogenation

    Directory of Open Access Journals (Sweden)

    Kovačević Marijana K.

    2007-01-01

    Full Text Available Mesoporous nanocristalline SnO2 supports were synthesized by a modified sol-gel method starting from SnCl2·2H2O and citric acid at pH 2.0 and 9.5. Noble metal was introduced via wet impregnation using PdCl2 as active phase precursor. Catalysts activities in water denitration were correlated with their textural, structural and morphological properties using LTNA (BET, XRD and SEM/EDS analysis. Lower pH value during the catalyst synthesis resulted in a final material characterized with more developed porosity and higher surface area. Although both catalysts turned out to be tailored from nanoscale crystallites, higher pore fraction of mesopores resulting from the synthesis in acidic conditions, was found to be responsible for superior catalytic behavior.

  17. Inverting the diastereoselectivity of the mukaiyama-michael addition with graphite-based catalysts

    KAUST Repository

    Acocella, Maria Rosaria

    2014-02-07

    Here, we show that graphite-based catalysts, mainly graphite oxide (GO) and exfoliated GO, are effective recyclable catalysts for a relevant stereoselective Mukaiyama-Michael addition, outperforming currently available catalysts. Moreover, the graphite-based catalysts described here invert the diastereoselectivity relative to that observed with known catalysts, with the unprecedented large prevalence of the anti diastereoisomer. This inverted diastereoselectivity is increased when the catalyst concentration is reduced and after catalyst recycling. Density functional theory calculations suggest that the selectivity is determined by two types of supramolecular interactions operating between the catalyst and the substrates at the diastereoselectivity- determining transition state, specifically, the π-stacking of b-nitrostyrene with graphite and the van der Waals interaction between the SiMe3 group of the silyl ether and the graphite. © 2013 American Chemical Society.

  18. Reversible hydrogen storage using CO2 and a proton-switchable iridium catalyst in aqueous media under mild temperatures and pressures.

    Science.gov (United States)

    Hull, Jonathan F; Himeda, Yuichiro; Wang, Wan-Hui; Hashiguchi, Brian; Periana, Roy; Szalda, David J; Muckerman, James T; Fujita, Etsuko

    2012-03-18

    Green plants convert CO(2) to sugar for energy storage via photosynthesis. We report a novel catalyst that uses CO(2) and hydrogen to store energy in formic acid. Using a homogeneous iridium catalyst with a proton-responsive ligand, we show the first reversible and recyclable hydrogen storage system that operates under mild conditions using CO(2), formate and formic acid. This system is energy-efficient and green because it operates near ambient conditions, uses water as a solvent, produces high-pressure CO-free hydrogen, and uses pH to control hydrogen production or consumption. The extraordinary and switchable catalytic activity is attributed to the multifunctional ligand, which acts as a proton-relay and strong π-donor, and is rationalized by theoretical and experimental studies.

  19. Hydrogen-Based Energy Conservation System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Sustainable Innovations is developing a technology for efficient separation and compression of hydrogen gas. The electrochemical hydrogen separator and compressor...

  20. Two-Dimensional MXenes as Catalysts for Electrochemical Hydrogen Evolution: A Computational Screening Study

    DEFF Research Database (Denmark)

    Pandey, Mohnish; Thygesen, Kristian Sommer

    2017-01-01

    is assessed via the calculated standard heat of formation. We find that most of the MXenes are metallic, and we investigate their performance as electrocatalysts for the hydrogen evolution reaction(HER) using the free energy of hydrogen adsorption at equilibrium coverage as an activity descriptor. For a given...

  1. Session 4: Solid solution sulfide photo-catalysts for hydrogen evolution under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Tsuji, I.; Kato, H. [Tokyo Univ., Faculty of Science, Dept. of Applied Chemistry (Japan); Kudo, A.; Kobayashi, H. [Kurashiki Univ. of Science and the Arts, (Japan); Kudo, A. [Japan Science and Technology Agency, Core Research for Evolutional Science and Technology (Japan)

    2004-07-01

    In the present study, we tried to make a new visible-light driven photo-catalyst for H{sub 2} evolution by making solid solutions between ZnS photo-catalyst with a wide band gap, and AgInS{sub 2} and CuInS{sub 2} with narrow band gaps. The photophysical and photo-catalytic properties of (MIn){sub x}Zn{sub 2(1-x)}S{sub 2} (M=Cu, Ag) solid solutions were investigated. (authors)

  2. Pd-Diimine : A Highly Selective Catalyst System for the Base-Free Oxidative Heck Reaction

    NARCIS (Netherlands)

    Gottumukkala, Aditya L.; Teichert, Johannes F.; Heijnen, Donis; Eisink, Niek; van Dijk, Simon; Ferrer, Catalina; van den Hoogenband, Adri; Minnaard, Adriaan J.

    2011-01-01

    Pd(OAc)(2)/3 is an efficient catalyst system for the base-free oxidative Heck reaction that outperforms the currently available catalysts for the more challenging substrates studied. The catalyst system is highly selective, and works at room temperature with dioxygen as the oxidant.

  3. Alloy catalyst material

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to a novel alloy catalyst material for use in the synthesis of hydrogen peroxide from oxygen and hydrogen, or from oxygen and water. The present invention also relates to a cathode and an electrochemical cell comprising the novel catalyst material, and the process use...... of the novel catalyst material for synthesising hydrogen peroxide from oxygen and hydrogen, or from oxygen and water....

  4. Hydrogen peroxide modified Mg-Al-O oxides supported Pt-Sn catalysts for paraffin dehydrogenation

    NARCIS (Netherlands)

    Lai, Y.; He, Songbo; Luo, S.; Bi, W.; Li, XianRu; Sun, Chenglin; Seshan, Kulathuiyer

    2015-01-01

    In this work, a new method to prepare Mg–Al–O oxide by co-precipitation method with addition of H2O2 was developed. The application of Mg–Al–O as a support of Pt–Sn catalysts for paraffin dehydrogenation was investigated. Characterization results indicated that modification of H2O2 (i) enlarged the

  5. Turning a Cr-based heterogeneous ethylene polymerisation catalyst into a selective ethylene trimerisation catalyst

    NARCIS (Netherlands)

    Nenu, N.C.; Bodart, P.; Weckhuysen, B.M.

    2007-01-01

    A Phillips Cr/SiO2 polymerisation catalyst was converted into an ethylene trimerisation catalyst after assembling new active sites on the silica surface in the presence of TAC (1,3,5-triphenylhexahydro 1,3,5-triazacyclohexane) as ligand and CH2Cl2 as solvent. The reaction conditions play a role in

  6. Recent Development in Hydrogen Evolution Reaction Catalysts and Their Practical Implementation

    DEFF Research Database (Denmark)

    Vesborg, Peter Christian Kjærgaard; Seger, Brian; Chorkendorff, Ib

    2015-01-01

    conditions offering nearly platinum like catalytic performance. The developments have been particularly fast in the last 5 years, and the present Perspective highlights key developments and discusses them, along with hydrogen evolution in general, in the context of the global energy problem.......The past 10 years have seen great advances in the field of electrochemical hydrogen evolution. In particular, several new nonprecious metal electrocatalysts, for example, the MoS2 or the Ni2P family of materials, have emerged as contenders for electrochemical hydrogen evolution under harsh acidic...

  7. Effects of carbon nanotubes and metal catalysts on hydrogen storage in magnesium nanocomposites.

    Science.gov (United States)

    Yao, X; Wu, C Z; Wang, H; Cheng, H M; Lu, G Q

    2006-02-01

    This paper reports a study on nanostructured magnesium composites with carbon nanotubes (CNTs) and catalytic transition metals with high H2 adsorption capacity and fast adsorption kinetics at reduced hydrogenation temperatures. Nanostructures in such a composite are shown to be responsible for improvements in both adsorption capacity and kinetics. It is found that the carbon nanotubes significantly increase the hydrogen storage capacity, and the catalytic transition metals (Fe and Ti) greatly improve the kinetics. This could be understood from the enhancement of diffusion by CNTs and decrease in energy barrier of hydrogen dissociation at the magnesium surface.

  8. Ultrasound assisted selective catalytic transfer hydrogenation of soybean oil using 5% Pd/C as catalyst under ambient conditions in water.

    Science.gov (United States)

    Sancheti, Sonam V; Gogate, Parag R

    2017-09-01

    Catalytic transfer hydrogenation (CTH) is an alternative approach that does not require the use of potentially dangerous hydrogen gas. Pd/C is the most favoured catalyst for the selective hydrogenation of soybean oil yielding lower extent of formation of stearic acid and trans-isomer, which have adverse health effects. The present work deals with intensification of catalytic transfer hydrogenation of soybean oil in the presence of 5wt.% Pd/C using ultrasound under ambient reaction conditions. The effect of important operating parameters such as ultrasound power, temperature, type of hydrogen donor, catalyst loading and donor concentration on the progress of reaction has been investigated. It was established that the maximum extent of hydrogenation as indicated by reduction in iodine value from 135 to 95 was observed under optimized conditions of irradiation power as 100W, 22kHz frequency, 90% duty cycle, ammonium formate concentration of 0.32mol/50ml water and 2% (w/w) Pd/C loading at ambient temperature and pressure in the presence of water as solvent. The approach also offered excellent selectivity with much lower trans-isomer formation as compared to the conventional approach of high pressure hydrogenation. Overall, the work has successfully demonstrated process intensification benefits due to the use of ultrasound for the Pd/C catalyzed transfer hydrogenation of soybean oil. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Polymer-based chromophore-catalyst assemblies for solar energy conversion

    Science.gov (United States)

    Leem, Gyu; Sherman, Benjamin D.; Schanze, Kirk S.

    2017-12-01

    The synthesis of polymer-based assemblies for light harvesting has been motivated by the multi-chromophore antennas that play a role in natural photosynthesis for the potential use in solar conversion technologies. This review describes a general strategy for using polymer-based chromophore-catalyst assemblies for solar-driven water oxidation at a photoanode in a dye-sensitized photoelectrochemical cell (DSPEC). This report begins with a summary of the synthetic methods and fundamental photophysical studies of light harvesting polychormophores in solution which show these materials can transport excited state energy to an acceptor where charge-separation can occur. In addition, studies describing light harvesting polychromophores containing an anchoring moiety (ionic carboxylate) for covalent bounding to wide band gap mesoporous semiconductor surfaces are summarized to understand the photophysical mechanisms of directional energy flow at the interface. Finally, the performance of polychromophore/catalyst assembly-based photoanodes capable of light-driven water splitting to oxygen and hydrogen in a DSPEC are summarized.

  10. Polymer-based chromophore-catalyst assemblies for solar energy conversion.

    Science.gov (United States)

    Leem, Gyu; Sherman, Benjamin D; Schanze, Kirk S

    2017-01-01

    The synthesis of polymer-based assemblies for light harvesting has been motivated by the multi-chromophore antennas that play a role in natural photosynthesis for the potential use in solar conversion technologies. This review describes a general strategy for using polymer-based chromophore-catalyst assemblies for solar-driven water oxidation at a photoanode in a dye-sensitized photoelectrochemical cell (DSPEC). This report begins with a summary of the synthetic methods and fundamental photophysical studies of light harvesting polychormophores in solution which show these materials can transport excited state energy to an acceptor where charge-separation can occur. In addition, studies describing light harvesting polychromophores containing an anchoring moiety (ionic carboxylate) for covalent bounding to wide band gap mesoporous semiconductor surfaces are summarized to understand the photophysical mechanisms of directional energy flow at the interface. Finally, the performance of polychromophore/catalyst assembly-based photoanodes capable of light-driven water splitting to oxygen and hydrogen in a DSPEC are summarized.

  11. Structured catalysts and reactors for three phase catalytic reactions: manipulating activity and selectivity in nitrite hydrogenation

    NARCIS (Netherlands)

    Brunet Espinosa, Roger

    2016-01-01

    This work aimed at fabricating structured catalytic reactors for fast multiphase reactions, namely, nitrite hydrogenation and H2O2 decomposition. These reactors allowed a better understanding of these reactions and an improvement in terms of catalytic activity and selectivity.

  12. Selective Phenol Hydrogenation to Cyclohexanone over a Dual Supported Pd-Lewis Acid Catalyst

    National Research Council Canada - National Science Library

    Huizhen Liu; Tao Jiang; Buxing Han; Shuguang Liang; Yinxi Zhou

    2009-01-01

    Cyclohexanone is an industrially important intermediate in the synthesis of materials such as nylon, but preparing it efficiently through direct hydrogenation of phenol is hindered by over-reduction to cyclohexanol...

  13. The effect of preparation method on the performance of PtSn/Al2O3 catalysts for acetic acid hydrogenation

    Directory of Open Access Journals (Sweden)

    Zhang Ke

    2015-03-01

    Full Text Available PtSn/Al2O3 catalysts with a given loading of 1 wt% Pt and 1 wt% Sn were prepared by co-impregnation or successive impregnation with aqueous solutions of Pt, Sn precursors and a commercial alumina. The catalysts were characterized by N2 adsorption, H2-TPR (H2 temperature-programmed reduction, H2-pulse chemisorption, XPS (X-ray photoelectron spectroscopy and CO-FTIR (Fourier transform infrared spectroscopy, and tested in the hydrogenation of acetic acid. The results showed that the preparation method affected both the chemical properties and their performance in the hydrogenation of acetic acid. Sn enrichment on the catalysts surface was observed on the co-impregnated catalyst and catalyst in which the Pt precursor had been loaded first. It was found that the modification of Pt was a function of the sequence of Sn addition as revealed by CO-FTIR. Co-impregnated catalyst showed the highest activity and ethanol selectivity.

  14. Cobalt(III) Werner Complexes with 1,2-Diphenylethylenediamine Ligands: Readily Available, Inexpensive, and Modular Chiral Hydrogen Bond Donor Catalysts for Enantioselective Organic Synthesis.

    Science.gov (United States)

    Lewis, Kyle G; Ghosh, Subrata K; Bhuvanesh, Nattamai; Gladysz, John A

    2015-03-25

    In the quest for new catalysts that can deliver single enantiomer pharmaceuticals and agricultural chemicals, chemists have extensively mined the "chiral pool", with little in the way of inexpensive, readily available building blocks now remaining. It is found that Werner complexes based upon the D3 symmetric chiral trication [Co(en)3](3+) (en = 1,2-ethylenediamine), which features an earth abundant metal and cheap ligand type, and was among the first inorganic compounds resolved into enantiomers 103 years ago, catalyze a valuable carbon-carbon bond forming reaction, the Michael addition of malonate esters to nitroalkenes, in high enantioselectivities and without requiring inert atmosphere conditions. The title catalysts, [Co((S,S)-dpen)3](3+) ((S,S)-3 (3+)) 3X(-), employ a commercially available chiral ligand, (S,S)-1,2-diphenylethylenediamine. The rates and ee values are functions of the configuration of the cobalt center (Λ/Δ) and the counteranions, which must be lipophilic to solubilize the trication in nonaqueous media. The highest enantioselectivities are obtained with Λ and 2Cl(-)BArf (-), 2BF4 (-)BArf (-), or 3BF4 (-) salts (BArf (-) = B(3,5-C6H3(CF3)2)4 (-)). The substrates are not activated by metal coordination, but rather by second coordination sphere hydrogen bonding involving the ligating NH2 groups. Crystal structures and NMR data indicate enthalpically stronger interactions with the NH moieties related by the C3 symmetry axis, as opposed to those related by the C2 symmetry axes; rate trends and other observations suggest this to be the catalytically active site. Both Λ- and Δ-(S,S)-3 (3+) 2Cl(-)BArf (-) are effective catalysts for additions of β-ketoesters to RO2CN=NCO2R species (99-86% yields, 81-76% ee), which provide carbon-nitrogen bonds and valuable precursors to α-amino acids.

  15. Preparation and characterization oF Ru-Sn/Al2O3 catalysts for the hydrogenation of fatty acid methyl esters

    Directory of Open Access Journals (Sweden)

    Vanina A. Mazzieri

    2010-01-01

    Full Text Available Ru-Sn/Al2O3 catalysts with different Sn loadings were prepared by the coimpregnation method. Several characterization techniques such as TPR, pyridine TPD and catalytic tests for dehydrogenation and hydrogenolysis were used to evaluate and compare such catalysts. TPR results indicate that Sn is deposited both onto the support and as species strongly interacting with Ru. Such non selective deposition modifies the acid and metallic functions of the catalysts. Both total acidity and acid strength distribution are affected: total acidity decreases and new sites of lower acid strength are created. Both dehydrogenating and hydrogenolytic activities are strongly diminished by the addition of Sn. Results of catalytic tests for methyl oleate hydrogenation indicate that methyl stearate is the main product, with only minute amounts of oleyl alcohol produced, and that the addition of Sn diminishes the hydrogenation activity.

  16. Preparation and characterization of Ru-Sn/Al{sub 2}O{sub 3} catalysts for the hydrogenation of fatty acid methyl esters

    Energy Technology Data Exchange (ETDEWEB)

    Mazzieri, Vanina A.; Sad, Mario R.; Vera, Carlos R.; Pieck, Carlos L. [Consejo Nacional de Investigaciones Cientificas y Tecnicas, Santa Fe (Argentina). Universidad Nacional del Litoral. Inst. de Investigaciones en Catalisis y Petroquimica; Grau, Ricardo [Consejo Nacional de Investigaciones Cientificas y Tecnicas, Santa Fe (Argentina). Universidad Nacional del Litoral. Inst. de Desarrollo Tecnologico para la Industria Quimica

    2010-07-01

    Ru-Sn/Al{sub 2}O{sub 3} catalysts with different Sn loadings were prepared by the coimpregnation method. Several characterization techniques such as TPR, pyridine TPD and catalytic tests for dehydrogenation and hydrogenolysis were used to evaluate and compare such catalysts. TPR results indicate that Sn is deposited both onto the support and as species strongly interacting with Ru. Such non selective deposition modifies the acid and metallic functions of the catalysts. Both total acidity and acid strength distribution are affected: total acidity decreases and new sites of lower acid strength are created. Both dehydrogenating and hydrogenolytic activities are strongly diminished by the addition of Sn. Results of catalytic tests for methyl oleate hydrogenation indicate that methyl stearate is the main product, with only minute amounts of oleyl alcohol produced, and that the addition of Sn diminishes the hydrogenation activity. (author)

  17. Characterization of catalysts Rh and Ni/Ce{sub x}Zr{sub 1-x}O{sub 2} for hydrogen production by ethanol steam reforming; Caracterisation de catalyseurs Rhodium et Nickel/ Ce{sub x}Zr{sub 1-x}O{sub 2} pour la production d'hydrogene par vaporeformage de l'ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Birot, A

    2005-07-01

    This work concerned a study on catalytic behaviour of metallic catalysts (Rh or Ni) supported on earth rare oxides Ce{sub x}Zr{sub 1-x}O{sub 2} in ethanol steam reforming in order to produce hydrogen. Catalyst 1%Rh/Ce0,50Zr0,50O{sub 2} showed a good activity with a good hydrogen yield. We turned a study onto understanding inter-conversion reaction between H{sub 2}, CO and CO{sub 2} which lead to CH{sub 4} formation. We also studied intrinsic properties of catalysts. We confirmed basic character of catalysts and a good hydrogenation activity. A good activity in CO hydrogenation allowed to evidence a necessity to use a catalyst which is less active in hydrogenation reaction and with a basic character in order to improve hydrogen yield. (author)

  18. Production of hydrogen from methane decomposition using nanosized carbon black as catalyst in a fluidized-bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jiuling [Tianjin Key Laboratory of Applied Catalysis Science and Technology, School of Chemical Engineering, Tianjin University, Tianjin 300072 (China); Division of Chemical Engineering, the University of Queensland, St Lucia, Brisbane, QLD 4072 (Australia); He, Miao; Wang, Gaowei; Li, Yongdan [Tianjin Key Laboratory of Applied Catalysis Science and Technology, School of Chemical Engineering, Tianjin University, Tianjin 300072 (China); Zhu, Zhonghua John [Division of Chemical Engineering, the University of Queensland, St Lucia, Brisbane, QLD 4072 (Australia)

    2009-12-15

    Nanosized carbon black (NCB) was employed as catalyst for methane decomposition to produce hydrogen in a fluidized-bed reactor. The carbon atoms of the surface defects of NCB act as active sites in this reaction. The activity of NCB is improved after more defects in the surface of NCB are generated after the treatment in nitric acid and calcination in nitrogen gas. The loading of small amounts of Ni and Co can obviously increase the initial activity of NCB, however, their activity deceases very quickly after the reaction begins due to the encapsulation of the corresponding metal particles inside amorphous carbon produced from methane decomposition. After reaction, the formed carbon was found to grow into carbon flakes and cover the surface of NCB. The investigation with TEM and SEM indicates that they may form from a new carbon crystallite, not build upon the existing hexagon layer in the surface defects of NCB. (author)

  19. Numerical Analysis of the Pressure Drop on a Flow Channel Filled with Catalysts for Nuclear Hydrogen Production System

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sung Deok; Kim, C. S.; Kim, M. H.; Kim, Y. W. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Seo, D. U.; Park, G. C. [Seoul National Univ., Seoul (Korea, Republic of)

    2013-10-15

    Designing a process heat exchanger (PHE) is one of the main technical challenges in the development of a nuclear hydrogen production system. The PHE provides an interface between the helium gas and the sulfuric acid gas. The SO3 gas is heated and decomposed into SO2 and O2 in the PHE. For this reason, PHE is also called a sulfur trioxide decomposer. The Korea Atomic Energy Research Institute (KAERI) has developed a hybrid-design decomposer to withstand severe operating conditions. Figure 1 shows the layout of the PHE which has a hybrid form of its flow channel geometry; there is a printed-circuit form on the primary helium side and a plate-fin form on the secondary SO3 side. There are many widespread correlations for the porous media such as the Carman, Ergun, Zhavoronkov et al., Susskind and Becker and Reichelt correlation. In the nuclear field, the KTA correlation was developed for a reactor core design for a high-temperature gas-cooled reactor. In this paper, we discussed a numerical analysis and validation of a pressure drop on a SO3 flow channel filled with various sized catalysts. We discussed a numerical analysis and validation of a pressure drop on a flow channel filled with catalysts in the channel. The results of the pressure drop simulation are compared with the results obtained using well-known empirical correlations. From the comparison results, the validity of the two-dimensional numerical analysis is not shown. The main reason may be due to a discord of the channel geometry and the extreme irregularity in the size of the catalyst. It should be accomplished by comparing its results with the experimental data, yet there are no experimental data available up to now.

  20. Hydrogen treatment of titanium based alloys

    Science.gov (United States)

    Losertová, M.; Hartmann, M.; Schindler, I.; Drápala, J.

    2017-11-01

    The positive effect of the hydrogen on hot deformation behaviour at 700 and 750 °C was investigated after thermal hydrogen treatment of Ti6Al4V and Ti26Nb alloys. Comparing the results obtained for the non-hydrogenated and hydrogenated specimens of both alloys, it was found that the hydrogen content as high as 1325 wt. ppm has an obvious benefit effect on high temperature deformation behaviour in the Ti6Al4V alloy by stabilizing beta phase and lowering thermal deformation resistance. In the case of Ti26Nb alloy the hydrogen content of 2572 wt. ppm suppressed stress instabilities during hot compression but slightly increased thermal deformation resistance. The microstructure study was performed before and after the isothermal compression tests on the specimens in hydrogenated as well as in non-hydrogenated condition. The hydrogen amounts in the specimens were measured by means of an analyser LECO RH600.

  1. Fluorometric method for the determination of hydrogen peroxide and glucose with Fe3O4 as catalyst.

    Science.gov (United States)

    Gao, Yuan; Wang, Guannan; Huang, Hui; Hu, Junjie; Shah, Syed Mazhar; Su, Xingguang

    2011-08-15

    In this paper, we utilized the instinct peroxidase-like property of Fe(3)O(4) magnetic nanoparticles (MNPs) to establish a new fluorometric method for determination of hydrogen peroxide and glucose. In the presence of Fe(3)O(4) MNPs as peroxidase mimetic catalyst, H(2)O(2) was decomposed into radical that could quench the fluorescence of CdTe QDs more efficiently and rapidly. Then the oxidization of glucose by glucose oxidase was coupled with the fluorescence quenching of CdTe QDs by H(2)O(2) producer with Fe(3)O(4) MNPs catalyst, which can be used to detect glucose. Under the optimal reaction conditions, a linear correlation was established between fluorescence intensity ratio I(0)/I and concentration of H(2)O(2) from 1.8 × 10(-7) to 9 × 10(-4)mol/L with a detection limit of 1.8 × 10(-8)mol/L. And a linear correlation was established between fluorescence intensity ratio I(0)/I and concentration of glucose from 1.6 × 10(-6) to 1.6 × 10(-4)mol/L with a detection limit of 1.0 × 10(-6)mol/L. The proposed method was applied to the determination of glucose in human serum samples with satisfactory results. Copyright © 2011 Elsevier B.V. All rights reserved.

  2. Nano-structured Platinum-based Catalysts for the Complete Oxidation of Ethylene Glycol and Glycerol

    Science.gov (United States)

    Falase, Akinbayowa

    Direct alcohol fuel cells are a viable alternative to the traditional hydrogen PEM fuel cell. Fuel versatility, integration with existing distribution networks, and increased safety when handling these fuels increases their appeal for portable power applications. In order to maximize their utility, the liquid fuel must be fully oxidized to CO2 so as to harvest the full amount of energy. Methanol and ethanol are widely researched as potential fuels to power these devices, but methanol is a toxic substance, and ethanol has a much lower energy density than other liquids such as gasoline or glucose. Oxidation of complex fuels is difficult to realize, due to difficulty in breaking carbon-carbon bonding and poisoning of the catalysts by oxidative byproducts. In order to achieve the highest efficiency, an anode needs to be engineered in such a way as to maximize activity while minimizing poisoning effects of reaction byproducts. We have engineered an anode that uses platinum-based catalysts that is capable of completely oxidizing ethylene glycol and glycerol in neutral and alkaline media with little evidence of CO poisoning. We have constructed a hybrid anode consisting of a nano-structured PtRu electrocatayst with an NAD-dependent alcohol dehydrogenase for improved oxidation of complex molecules. A nano-structured PtRu catalyst was used to oxidize ethylene glycol and glycerol in neutral media. In situ infrared spectroscopy was used to verify complete oxidation via CO2 generation. There was no evidence of poisoning by CO species. A pH study was performed to determine the effect of pH on oxidative current. The peak currents did not trend at 60 mV/pH unit as would be expected from the Nernst equation, suggesting that adsorption of fuel to the surface of the electrode is not an electron-transfer step. We synthesized nano-structured PtRu, PtSn, and PtRuSn catalysts for oxidation of ethylene glycol and glycerol in alkaline media. The PtRu electrocatalyst the highest oxidative

  3. Polyoxomolybdate-Calix[4]arene Hybrid: A Catalyst for Sulfoxidation Reactions with Hydrogen Peroxide.

    Science.gov (United States)

    Meninno, Sara; Parrella, Alessandro; Brancatelli, Giovanna; Geremia, Silvano; Gaeta, Carmine; Talotta, Carmen; Neri, Placido; Lattanzi, Alessandra

    2015-10-16

    An easily accessible polyoxomolybdate-calix[4]arene hybrid 1 has been synthesized and applied as a heterogeneous catalyst in the sulfoxidation of thioethers to sulfoxides and to sulfones under strictly stoichiometric amounts of 30% H2O2 in CH3CN as the solvent. This study represents the first promising example of successful employment of calixarenes-polyoxometalate (POM) hybrid materials in the area of catalytic oxidations.

  4. Catalytic Hydrogenation of Levulinic Acid in Water into g-Valerolactone over Bulk Structure of Inexpensive Intermetallic Ni-Sn Alloy Catalysts

    Directory of Open Access Journals (Sweden)

    Rodiansono Rodiansono

    2015-07-01

    Full Text Available A bulk structure of inexpensive intermetallic nickel-tin (Ni-Sn alloys catalysts demonstrated highly selective in the hydrogenation of levulinic acid in water into g-valerolactone. The intermetallic Ni-Sn catalysts were synthesized via a very simple thermochemical method from non-organometallic precursor at low temperature followed by hydrogen treatment at 673 K for 90 min. The molar ratio of nickel salt and tin salt was varied to obtain the corresponding Ni/Sn ratio of 4.0, 3.0, 2.0, 1.5, and 0.75. The formation of Ni-Sn alloy species was mainly depended on the composition and temperature of H2 treatment. Intermetallics Ni-Sn that contain Ni3Sn, Ni3Sn2, and Ni3Sn4 alloy phases are known to be effective heterogeneous catalysts for levulinic acid hydrogenation giving very excellence g-valerolactone yield of >99% at 433 K, initial H2 pressure of 4.0 MPa within 6 h. The effective hydrogenation was obtained in H2O without the formation of by-product. Intermetallic Ni-Sn(1.5 that contains Ni3Sn2 alloy species demonstrated very stable and reusable catalyst without any significant loss of its selectivity. © 2015 BCREC UNDIP. All rights reserved. Received: 26th February 2015; Revised: 16th April 2015; Accepted: 22nd April 2015  How to Cite: Rodiansono, R., Astuti, M.D., Ghofur, A., Sembiring, K.C. (2015. Catalytic Hydrogenation of Levulinic Acid in Water into g-Valerolactone over Bulk Structure of Inexpensive Intermetallic Ni-Sn Alloy Catalysts. Bulletin of Chemical Reaction Engineering & Catalysis, 10 (2: 192-200. (doi:10.9767/bcrec.10.2.8284.192-200Permalink/DOI: http://dx.doi.org/10.9767/bcrec.10.2.8284.192-200  

  5. Boron-Based Hydrogen Storage: Ternary Borides and Beyond

    Energy Technology Data Exchange (ETDEWEB)

    Vajo, John J. [HRL Laboratories, LLC, Malibu, CA (United States)

    2016-04-28

    DOE continues to seek reversible solid-state hydrogen materials with hydrogen densities of ≥11 wt% and ≥80 g/L that can deliver hydrogen and be recharged at moderate temperatures (≤100 °C) and pressures (≤100 bar) enabling incorporation into hydrogen storage systems suitable for transportation applications. Boron-based hydrogen storage materials have the potential to meet the density requirements given boron’s low atomic weight, high chemical valance, and versatile chemistry. However, the rates of hydrogen exchange in boron-based compounds are thus far much too slow for practical applications. Although contributing to the high hydrogen densities, the high valance of boron also leads to slow rates of hydrogen exchange due to extensive boron-boron atom rearrangements during hydrogen cycling. This rearrangement often leads to multiple solid phases occurring over hydrogen release and recharge cycles. These phases must nucleate and react with each other across solid-solid phase boundaries leading to energy barriers that slow the rates of hydrogen exchange. This project sought to overcome the slow rates of hydrogen exchange in boron-based hydrogen storage materials by minimizing the number of solid phases and the boron atom rearrangement over a hydrogen release and recharge cycle. Two novel approaches were explored: 1) developing matched pairs of ternary borides and mixed-metal borohydrides that could exchange hydrogen with only one hydrogenated phase (the mixed-metal borohydride) and only one dehydrogenated phase (the ternary boride); and 2) developing boranes that could release hydrogen by being lithiated using lithium hydride with no boron-boron atom rearrangement.

  6. Stationary inverted Lyman population formed from incandescently heated hydrogen gas with certain catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Mills, Randell L; Ray, Paresh C; Mayo, Robert M [BlackLight Power, Inc., 493 Old Trenton Road, Cranbury, NJ 08512 (United States)

    2003-07-07

    A new chemically generated plasma source is reported. The presence of gaseous Rb{sup +} or K{sup +} ions with thermally dissociated hydrogen formed a low applied temperature, extremely low voltage plasma called a resonant transfer or rt-plasma having strong vacuum ultraviolet emission. We propose an energetic catalytic reaction involving a resonant energy transfer between hydrogen atoms and Rb{sup +} or 2K{sup +} since Rb{sup +} to Rb{sup 2+}, 2K{sup +} to K + K{sup 2+}, and K to K{sup 3+} each provide a reaction with a net enthalpy equal to the potential energy of atomic hydrogen. Remarkably, a stationary inverted Lyman population was observed; thus, these catalytic reactions may pump a cw HI laser as predicted by a collisional radiative model used to determine that the observed overpopulation was above threshold.

  7. Hydrogen-Based Energy Conservation System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA and many others often rely on delivery of cryogenic hydrogen to meet their facility needs. NASA's Stennis Space Center is one of the largest users of hydrogen,...

  8. Ruthenium Water Oxidation Catalysts based on Pentapyridyl Ligands.

    Science.gov (United States)

    Gil-Sepulcre, Marcos; Böhler, Michael; Schilling, Mauro; Bozoglian, Fernando; Bachmann, Cyril; Scherrer, Dominik; Fox, Thomas; Spingler, Bernhard; Gimbert-Suriñach, Carolina; Alberto, Roger; Bofill, Roger; Sala, Xavier; Luber, Sandra; Richmond, Craig J; Llobet, Antoni

    2017-11-23

    Ruthenium complexes containing the pentapyridyl ligand 6,6''-(methoxy(pyridin-2-yl)methylene)di-2,2'-bipyridine (L-OMe) of general formula trans-[Ru II (X)(L-OMe-κ-N 5 )] n+ (X=Cl, n=1, trans-1 + ; X=H 2 O, n=2, trans-2 2+ ) have been isolated and characterized in solution (by NMR and UV/Vis spectroscopy) and in the solid state by XRD. Both complexes undergo a series of substitution reactions at oxidation state Ru II and Ru III when dissolved in aqueous triflic acid-trifluoroethanol solutions as monitored by UV/Vis spectroscopy, and the corresponding rate constants were determined. In particular, aqueous solutions of the Ru III -Cl complex trans-[Ru III (Cl)(L-OMe-κ-N 5 )] 2+ (trans-1 2+ ) generates a family of Ru aquo complexes, namely trans-[Ru III (H 2 O)(L-OMe-κ-N 5 )] 3+ (trans-2 3+ ), [Ru III (H 2 O) 2 (L-OMe-κ-N 4 )] 3+ (trans-3 3+ ), and [Ru III (Cl)(H 2 O)(L-OMe-κ-N 4 )] 2+ (trans-4 2+ ). Although complex trans-4 2+ is a powerful water oxidation catalyst, complex trans-2 3+ has only a moderate activity and trans-3 3+ shows no activity. A parallel study with related complexes containing the methyl-substituted ligand 6,6''-(1-pyridin-2-yl)ethane-1,1-diyl)di-2,2'-bipyridine (L-Me) was carried out. The behavior of all of these catalysts has been rationalized based on substitution kinetics, oxygen evolution kinetics, electrochemical properties, and density functional theory calculations. The best catalyst, trans-4 2+ , reaches turnover frequencies of 0.71 s -1 using Ce IV as a sacrificial oxidant, with oxidative efficiencies above 95 %. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Metallic cobalt nanoparticles imbedded into ordered mesoporous carbon: A non-precious metal catalyst with excellent hydrogenation performance.

    Science.gov (United States)

    Liu, Jiangyong; Wang, Zihao; Yan, Xiaodong; Jian, Panming

    2017-11-01

    Ordered mesoporous carbon (OMC)-metal composites have attracted great attention owing to their combination of high surface area, controlled pore size distribution and physicochemical properties of metals. Herein, we report the cobalt nanoparticles/ordered mesoporous carbon (CoNPs@OMC) composite prepared by a one-step carbonization/reduction process assisted by a hydrothermal pre-reaction. The CoNPs@OMC composite presents a high specific surface area of 544m 2 g -1 , and the CoNPs are uniformly imbedded or confined in the ordered mesoporous carbon matrix. When used as a non-precious metal-containing catalyst for hydrogenation reduction of p-nitrophenol and nitrobenzene, it demonstrates high efficiency and good cycling stability. Furthermore, the CoNPs@OMC composite can be directly used to catalyze the Fischer-Tropsch synthesis for the high-pressure CO hydrogenation, and presents a good catalytic selectivity for C 5 + hydrocarbons. The excellent catalytic performance of the CoNPs@OMC composite can be ascribed to synergistic effect between the high specific surface area, mesoporous structure and well-imbedded CoNPs in the carbon matrix. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Tuning the properties of copper-based catalysts based on molecular in situ studies of model systems.

    Science.gov (United States)

    Stacchiola, Darío J

    2015-07-21

    Studying catalytic processes at the molecular level is extremely challenging, due to the structural and chemical complexity of the materials used as catalysts and the presence of reactants and products in the reactor's environment. The most common materials used on catalysts are transition metals and their oxides. The importance of multifunctional active sites at metal/oxide interfaces has been long recognized, but a molecular picture of them based on experimental observations is only recently emerging. The initial approach to interrogate the surface chemistry of catalysts at the molecular level consisted of studying metal single crystals as models for reactive metal centers, moving later to single crystal or well-defined thin film oxides. The natural next iteration consisted in the deposition of metal nanoparticles on well-defined oxide substrates. Metal nanoparticles contain undercoordinated sites, which are more reactive. It is also possible to create architectures where oxide nanoparticles are deposited on top of metal single crystals, denominated inverse catalysts, leading in this case to a high concentration of reactive cationic sites in direct contact with the underlying fully coordinated metal atoms. Using a second oxide as a support (host), a multifunctional configuration can be built in which both metal and oxide nanoparticles are located in close proximity. Our recent studies on copper-based catalysts are presented here as an example of the application of these complementary model systems, starting from the creation of undercoordinated sites on Cu(111) and Cu2O(111) surfaces, continuing with the formation of mixed-metal copper oxides, the synthesis of ceria nanoparticles on Cu(111) and the codeposition of Cu and ceria nanoparticles on TiO2(110). Catalysts have traditionally been characterized before or after reactions and analyzed based on static representations of surface structures. It is shown here how dynamic changes on a catalyst's chemical state

  11. MIS-based sensors with hydrogen selectivity

    Science.gov (United States)

    Li,; Dongmei, [Boulder, CO; Medlin, J William [Boulder, CO; McDaniel, Anthony H [Livermore, CA; Bastasz, Robert J [Livermore, CA

    2008-03-11

    The invention provides hydrogen selective metal-insulator-semiconductor sensors which include a layer of hydrogen selective material. The hydrogen selective material can be polyimide layer having a thickness between 200 and 800 nm. Suitable polyimide materials include reaction products of benzophenone tetracarboxylic dianhydride 4,4-oxydianiline m-phenylene diamine and other structurally similar materials.

  12. Natural manganese deposits as catalyst for decomposing hydrogen peroxide (discussion paper)

    NARCIS (Netherlands)

    Knol, A.H.; Lekkerkerker-Teunissen, K.; Van Dijk, J.C.

    2015-01-01

    Drinking water companies more and more implement Advanced Oxidation Processes (AOP) in their treatment schemes to increase the barrier against organic micropollutants (OMPs). It is necessary to decompose the excessive hydrogen peroxide after applying AOP to avoid negative effects in the following,

  13. Asymmetric hydrogenation of aromatic ketones by new recyclable ionic tagged ferrocene-ruthenium catalyst system.

    Science.gov (United States)

    Xu, Di; Zhou, Zhi-Ming; Dai, Li; Tang, Li-Wei; Zhang, Jun

    2015-05-01

    Newly developed ferrocene-oxazoline-phosphine ligands containing quaternary ammonium ionic groups exhibited excellent catalytic performance for the ruthenium-catalyzed hydrogenation of aromatic ketonic substrates to give chiral secondary alcohols with high levels of conversions and enantioselectivities. Simple manipulation process, water tolerance, high activity and good recyclable property make this catalysis practical and appealing. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Engineering Two-Dimensional Transition Metal Dichalcogenide Catalysts for Water-Splitting Hydrogen Generation

    DEFF Research Database (Denmark)

    Cao, Xianyi; Tang, Yingying; Duus, Jens Øllgaard

    2017-01-01

    Development of advanced energy conversion and storage technologies is essential for optimizing the integration of sustainable energy resources into current-running power grid systems. As one of the key energy-storage carriers, hydrogen (H2) possesses ultrahigh gravimetric energy density, eco...

  15. Graphene/TiO2 hydrogel: a potential catalyst to hydrogen evolution ...

    Indian Academy of Sciences (India)

    Graphene hydrogels were prepared by the addition of L-ascorbic acid to GO suspensions and subsequent heating at 90 ∘ C. Composite hydrogels of graphene and titanium (IV) oxide (TiO 2 ) were synthesized with various TiO 2 to GO mass ratios. Composites were applied to photocatalytic hydrogen evolution reaction ...

  16. Magnetic Silica-Supported Ruthenium Nanoparticles: An Efficient Catalyst for Transfer Hydrogenation of Carbonyl Compounds

    Science.gov (United States)

    One-pot synthesis of ruthenium nanoparticles on magnetic silica is described which involve the in situ generation of magnetic silica (Fe3O4@ SiO2) and ruthenium nano particles immobilization; the hydration of nitriles and transfer hydrogenation of carbonyl compounds occurs in hi...

  17. Crotonaldehyde hydrogenation on Rh/TiO2 catalysts. In situ DRIFTS studies

    NARCIS (Netherlands)

    Reyes, P.; Aguirre, M. del C.; Melian Cabrera, Ignacio; Lopez Granados, M.; Fierro, J.L.G.

    2002-01-01

    The surface and catalytic properties in the vapor-phase hydrogenation of crotonaldehyde on Rh/TiO2 has been studied. It was found that a partial reduction of the support produces a surface decoration of the metal component. Thus, interfacial sites are created, which are responsible of an increase in

  18. Photocatalytic Hydrogen Production using Polymeric Carbon Nitride with a Hydrogenase and a Bioinspired Synthetic Ni Catalyst**

    OpenAIRE

    Caputo, Christine Amanda; Gross, Manuela A.; Lau, Vincent W; Cavazza, Christine; Lotsch, Bettina V.; Reisner, Erwin

    2014-01-01

    Solar-light-driven H2 production in water with a [NiFeSe]-hydrogenase (H2ase) and a bioinspired synthetic nickel catalyst (NiP) in combination with a heptazine carbon nitride polymer, melon (CNx), is reported. The semibiological and purely synthetic systems show catalytic activity during solar light irradiation with turnover numbers (TONs) of more than 50 000 mol H2 (mol H2ase)?1 and approximately 155 mol H2 (mol NiP)?1 in redox-mediator-free aqueous solution at pH 6 and 4.5, respectively. Bo...

  19. Hydrogen generation from renewable resources

    Energy Technology Data Exchange (ETDEWEB)

    Loges, Bjoern

    2009-09-04

    In this thesis, the hydrogen generation by dehydrogenation of 2-propanol and formic acid as model substances for renewable resources have been studied, which is of importance for hydrogen storage. For the base-assisted dehydrogenation of 2-propanol, a ruthenium diamine catalyst system has been investigated. For the selective decomposition of formic acid to hydrogen and carbon dioxide, a system has been established containing ruthenium catalysts and formic acid amine adducts as substrates. The best catalyst activity and productivity have been achieved with in situ generated ruthenium phosphine catalysts, e.g. [RuCl{sub 2}(benzene)]{sub 2} / dppe (TOF = 900 h{sup -1}, TON = 260,000). The gas evolved has been directly used in fuel cells. Furthermore, the influence of irradiation with visible light has been described for the ruthenium phosphine catalysts. (orig.)

  20. Palladium nanoparticles supported on fibrous-structured silica nanospheres (KCC-1): An efficient and selective catalyst for the transfer hydrogenation of alkenes

    KAUST Repository

    Qureshi, Ziyauddin

    2015-01-09

    An efficient palladium catalyst supported on fibrous silica nanospheres (KCC-1) has been developed for the hydrogenation of alkenes and α,β-unsaturated carbonyl compounds, providing excellent yields of the corresponding products with remarkable chemoselectivity. Comparison (high-resolution TEM, chemisorption) with analogous mesoporous (MCM-41, SBA-15) silica-supported Pd nanocatalysts prepared under identical conditions, demonstrates the advantage of employing the fibrous KCC-1 morphology versus traditional supports because it ensures superior accessibility of the catalytically active cores along with excellent Pd dispersion at high metal loading. This morphology ultimately leads to higher catalytic activity for the KCC-1-supported nanoparticles. The protocol developed for hydrogenation is advantageous and environmentally benign owing to the use of HCOOH as a source of hydrogen, water as a solvent, and because of efficient catalyst recyclability and durability. The recycled catalyst has been analyzed by XPS spectroscopy and TEM showing only minor changes in the oxidation state of Pd and in the morphology after the reaction, thus confirming the robustness of the catalyst.

  1. Selective hydrogenation of 1,3-butadiene from crude C{sub 4} cracker stream with a solid catalyst with ionic liquid layer (SCILL). DSC and solubility study

    Energy Technology Data Exchange (ETDEWEB)

    Mangartz, T.; Korth, W.; Kern, C.; Jess, A. [Bayreuth Univ. (Germany). Dept. of Chemical Engineering

    2013-11-01

    In petroleum as well as in fine chemical industry, selective catalytic hydrogenation is an important reaction. The selective hydrogenation of 1,3-butadiene (BD) to butene (trans-,1- and cis-butene) from the crude C4 steam cracker fraction represents one example, but under today's technical conditions undesired butane forms inevitably in relevant amounts. To increase the butene yield, the concept of Solid Catalyst with Ionic Liquid Layer (SCILL) was employed. The SCILL catalyst, in contrast to the uncoated catalyst, yielded a remarkably high selectivity to butenes (S{sub butenes} > 99 %) even at high residence times or at high hydrogen partial pressure. Nearly no butane (S{sub butane} {approx} 0 %) was analytically detected. We expected that due to different solubility, the poorer soluble compounds discharged from the ionic liquid and, thus, caused the shift in selectivity to a great extent. Temperature dependent solubility measurements in the used ionic liquid ([DMIM][DMP]) revealed that the order of increasing solubility is 1,3-butadiene > butenes > butane which matches the assumption. However, since differences in solubility cannot explain this SCILL effect satisfyingly, ionic liquids are expected to affect the surface of the catalyst (side-specific ligand-type effect). Investigations using spectroscopic methods (e.g. FTIR) confirmed this suggestion. (orig.)

  2. Effects of preparation method on the performance of Ni/Al(2)O(3) catalysts for hydrogen production by bio-oil steam reforming.

    Science.gov (United States)

    Li, Xinbao; Wang, Shurong; Cai, Qinjie; Zhu, Lingjun; Yin, Qianqian; Luo, Zhongyang

    2012-09-01

    Steam reforming of bio-oil derived from the fast pyrolysis of biomass is an economic and renewable process for hydrogen production. The main objective of the present work has been to investigate the effects of the preparation method of Ni/Al(2)O(3) catalysts on their performance in hydrogen production by bio-oil steam reforming. The Ni/Al(2)O(3) catalysts were prepared by impregnation, co-precipitation, and sol-gel methods. XRD, XPS, H(2)-TPR, SEM, TEM, TG, and N(2) physisorption measurements were performed to characterize the texture and structure of the catalysts obtained after calcination and after their subsequent use. Ethanol and bio-oil model compound were selected for steam reforming to evaluate the catalyst performance. The catalyst prepared by the co-precipitation method was found to display better performance than the other two. Under the optimized reaction conditions, an ethanol conversion of 99% and a H(2) yield of 88% were obtained.

  3. Photoelectrochemical based direct conversion systems for hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Kocha, S.; Peterson, M.; Arent, D. [National Renewable Energy Lab., Golden, CO (United States)] [and others

    1996-10-01

    Photon driven, direct conversion systems consist of a light absorber and a water splitting catalyst as a monolithic system; water is split directly upon illumination. This one-step process eliminates the need to generate electricity externally and subsequently feed it to an electrolyzer. These configurations require only the piping necessary for transport of hydrogen to an external storage system or gas pipeline. This work is focused on multiphoton photoelectrochemical devices for production of hydrogen directly using sunlight and water. Two types of multijunction cells, one consisting of a-Si triple junctions and the other GaInP{sub 2}/GaAs homojunctions, were studied for the photoelectrochemical decomposition of water into hydrogen and oxygen from an aqueous electrolyte solution. To catalyze the water decomposition process, the illuminated surface of the device was modified either by addition of platinum colloids or by coating with ruthenium dioxide. These colloids have been characterized by gel electrophoresis.

  4. Hydrogen-based electrochemical energy storage

    Science.gov (United States)

    Simpson, Lin Jay

    2013-08-06

    An energy storage device (100) providing high storage densities via hydrogen storage. The device (100) includes a counter electrode (110), a storage electrode (130), and an ion conducting membrane (120) positioned between the counter electrode (110) and the storage electrode (130). The counter electrode (110) is formed of one or more materials with an affinity for hydrogen and includes an exchange matrix for elements/materials selected from the non-noble materials that have an affinity for hydrogen. The storage electrode (130) is loaded with hydrogen such as atomic or mono-hydrogen that is adsorbed by a hydrogen storage material such that the hydrogen (132, 134) may be stored with low chemical bonding. The hydrogen storage material is typically formed of a lightweight material such as carbon or boron with a network of passage-ways or intercalants for storing and conducting mono-hydrogen, protons, or the like. The hydrogen storage material may store at least ten percent by weight hydrogen (132, 134) at ambient temperature and pressure.

  5. Selective hydrogenation of acetylene on SiO{sub 2} supported Ni-In bimetallic catalysts: Promotional effect of In

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yanjun; Chen, Jixiang, E-mail: jxchen@tju.edu.cn

    2016-11-30

    Graphical abstract: A suitable Ni/In ratio remarkably enhanced the acetylene conversion, the selectivity to ethylene and the catalyst stability. Display Omitted - Highlights: • There was a promotional effect of In on the performance of Ni/SiO{sub 2}. • A suitable Ni/In ratio was required for good performance of Ni{sub x}In/SiO{sub 2}. • Both geometrical and electronic effects of In contributed to good performance. • Ni/SiO{sub 2} deactivation is mainly owing to phase change from Ni to nickel carbide. • The carbonaceous deposit was the main reason for Ni{sub x}In/SiO{sub 2} deactivation. - Abstract: Ni/SiO{sub 2} and the bimetallic Ni{sub x}In/SiO{sub 2} catalysts with different Ni/In ratios were tested for the selective hydrogenation of acetylene, and their physicochemical properties before and after the reaction were characterized by means of N{sub 2}-sorption, H{sub 2}-TPR, XRD, TEM, XPS, H{sub 2} chemisorption, C{sub 2}H{sub 4}-TPD, NH{sub 3}-TPD, FT-IR of adsorbed pyridine, and TG/DTA and Raman. A promotional effect of In on the performance of Ni/SiO{sub 2} was found, and Ni{sub x}In/SiO{sub 2} with a suitable Ni/In ratio gave much higher acetylene conversion, ethylene selectivity and catalyst stability than Ni/SiO{sub 2}. This is ascribed to the geometrical isolation of the reactive Ni atoms with the inert In ones and the charge transfer from the In atoms to Ni ones, both of which are favorable for reducing the adsorption strength of ethylene and restraining the C−C hydrogenolysis and the polymerizations of acetylene and the intermediate compounds. On the whole, Ni{sub 6}In/SiO{sub 2} and Ni{sub 10}In/SiO{sub 2} had better performance. Nevertheless, with increasing the In content, the selectivity to the C4+ hydrocarbons tended to increase due to the enhanced catalyst acidity because of the charge transfer from the In atoms to Ni ones. As the Lewis acid ones, the In sites could promote the polymerization. The catalyst deactivation was also analyzed

  6. Reforming of Ethanol to Produce Hydrogen over PtRuMg/ZrO2 Catalyst

    Directory of Open Access Journals (Sweden)

    Josh Y. Z. Chiou

    2012-01-01

    Full Text Available A modified PtRu/ZrO2 catalyst with Mg is evaluated for the oxidative steam reforming of ethanol (OSRE and the steam reforming of ethanol (SRE. In order to understand the variation in the reaction mechanism on OSRE and SRE, further analysis of both fresh and used catalyst is concentrated on for TEM, TG, Raman, and TPR characterization. The results show that the OSRE reaction requires a higher temperature (∼390°C to achieve 100% ethanol conversion than the SRE reaction (∼2500°C. The distribution of CO is minor for both reactions (< 5% for OSRE, < 1% for SRE. This demonstrates that the water gas shift (WGS reaction is an important side-reaction in the reforming of ethanol to produce H2 and CO2. A comparison of the temperature of WGS (WGS shows it is lower for the SRE reaction (WGS∼250°C for SRE, ~340°C for OSRE.

  7. Advanced oxidation of rhodamine B with hydrogen peroxide over ZnCr layered double hydroxide catalysts

    Directory of Open Access Journals (Sweden)

    Nguyen Tien Thao

    2017-09-01

    Full Text Available Zn/Cr layered zinc hydroxide materials with different molar ratios of Cr/Zn have been synthesized through the coprecipitation method at pH of 9.0–9.5. At high Cr/Zn molar ratios of 0.5/1–1/3, the materials possess some layered structure with carbonate anions between the interlayer galleries. The catalysts present uniform particle sizes and quite high surface area. An isomorphous substitution of Zn2+ by Cr3+ in the brucite-like sheets makes the layered Cr-doped zinc hydroxides potential catalysts for efficient oxidation of rhodamine B with H2O2 solution. The experimental results indicated that the intra-lattice Cr3+ ions are more active than Cr2O3 components in the oxidative removal of rhodamine B. The degradation efficiency is dependent on the intra lattice Cr3+ contents and reaction variables. The Cr/Zn LDH gave a high decolorization (99% of rhodamine B at near neutral pH and room temperature.

  8. Aerobic Oxidation of Alcohols over Gold Catalysts: Role of Acid and Base

    DEFF Research Database (Denmark)

    Klitgaard, Søren Kegnæs; DeLa Riva, Andrew T.; Helveg, Stig

    2008-01-01

    Gold nanoparticles are deposited on potassium titanate nanowires and used as heterogeneous catalysts in the aerobic oxidation of benzyl alcohol in methanol to methyl benzoate at ambient conditions. The presence of a catalytic amount of base promotes the reaction and the formation of free benzoic ...... acid during the reaction poisons the catalyst. The activity however, of the catalyst can be restored again by addition of base.......Gold nanoparticles are deposited on potassium titanate nanowires and used as heterogeneous catalysts in the aerobic oxidation of benzyl alcohol in methanol to methyl benzoate at ambient conditions. The presence of a catalytic amount of base promotes the reaction and the formation of free benzoic...

  9. Ni-Based Catalysts for Low Temperature Methane Steam Reforming: Recent Results on Ni-Au and Comparison with Other Bi-Metallic Systems

    Directory of Open Access Journals (Sweden)

    Anna M. Venezia

    2013-06-01

    Full Text Available Steam reforming of light hydrocarbons provides a promising method for hydrogen production. Ni-based catalysts are so far the best and the most commonly used catalysts for steam reforming because of their acceptably high activity and significantly lower cost in comparison with alternative precious metal-based catalysts. However, nickel catalysts are susceptible to deactivation from the deposition of carbon, even when operating at steam-to-carbon ratios predicted to be thermodynamically outside of the carbon-forming regime. Reactivity and deactivation by carbon formation can be tuned by modifying Ni surfaces with a second metal, such as Au through alloy formation. In the present review, we summarize the very recent progress in the design, synthesis, and characterization of supported bimetallic Ni-based catalysts for steam reforming. The progress in the modification of Ni with noble metals (such as Au and Ag is discussed in terms of preparation, characterization and pretreatment methods. Moreover, the comparison with the effects of other metals (such as Sn, Cu, Co, Mo, Fe, Gd and B is addressed. The differences of catalytic activity, thermal stability and carbon species between bimetallic and monometallic Ni-based catalysts are also briefly shown.

  10. Atomic-scale insight into the origin of pyridine inhibition of MoS2-based hydrotreating catalysts

    DEFF Research Database (Denmark)

    Temel, Burcin; Tuxen, Anders K.; Kibsgaard, Jakob

    2010-01-01

    Basic nitrogen-containing compounds such as pyridine are well known to be inhibitors of the hydrodesulfurization (HDS) reaction for the MoS2-based catalysts. From an interplay of scanning tunneling microscopy (STM) experiments and density functional theory (DFT) calculations, atomic-scale insight...... also at the edges. The calculated DFT energies and simulated STM images allowed us to conclude that these species are pyridinium ions located at the catalytically active brim sites. Furthermore, the DFT results for the vibrational modes of the adsorbed pyridinium species agree well with those observed...... in earlier IR experiments on high surface alumina-supported MoS2 catalyst. The adsorption sites appear to be very similar to the brim sites involved in hydrogenation reactions in HDS. Thus, the combined STM and DFT results provide new atomic-scale insight into the inhibition effect of basic N...

  11. Monodisperse Ag/Pd core/shell nanoparticles assembled on reduced graphene oxide as highly efficient catalysts for the transfer hydrogenation of nitroarenes.

    Science.gov (United States)

    Metin, Önder; Can, Hasan; Şendil, Kıvılcım; Gültekin, Mehmet Serdar

    2017-07-15

    Addressed herein is a facile seed-mediated synthesis of Ag/Pd core/shell nanoparticles (NPs) and their assembly on reduced graphene oxide (rGO) to catalyze the transfer hydrogenation of nitroarenes to anilines using ammonia borane (AB) as a hydrogen donor under ambient conditions. Monodisperse Ag/Pd core/shell NPs with controllable Pd shell-thickness were synthesized by the means of thermal decomposition of palladium(II) bromide over as-prepared Ag NPs in the mixture of oleylamine and oleic acid at 220°C. As-synthesized Ag/Pd core/shell NPs were characterized by TEM, HR-TEM, XRD, XPS, UV-Vis spectroscopy and ICP-MS and then they were assembled on reduced graphene oxide (rGO). Next, rGO@Ag/Pd catalysts were tested in the transfer hydrogenation of nitroarenes in which ammonia borane (AB) was used as a hydrogen donor at room temperature. It was demonstrated that the thickness of the Pd shell has a significant effect on the catalytic activity of rGO@Ag/Pd catalysts and the 1.75nm Pd shell provided the highest performance in the transfer hydrogenation reactions. The rGO@Ag/Pd catalyzed transfer hydrogenation reactions were tested over a variety of nitroarenes (total 16 examples) and they were all converted to the corresponding aniline derivatives with high yields in 5-15min under ambient conditions. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Study of Supported Nickel Catalysts Prepared by Aqueous Hydrazine Method. Hydrogenating Properties and Hydrogen Storage: Support Effect. Silver Additive Effect; Catalyseurs de nickel supportes prepares par la methode de l'hydrazine aqueuse. Proprietes hydrogenantes et stockage d'hydrogene. Effet du support. Effet de l'ajout d'argent

    Energy Technology Data Exchange (ETDEWEB)

    Wojcieszak, R

    2006-06-15

    We have studied Ni or NiAg nano-particles obtained by the reduction of nickel salts (acetate or nitrate) by hydrazine and deposited by simple or EDTA-double impregnation on various supports ({gamma}-Al{sub 2}O{sub 3}, amorphous or crystallized SiO{sub 2}, Nb{sub 2}O{sub 5}, CeO{sub 2} and carbon). Prepared catalysts were characterized by different methods (XRD, XPS, low temperature adsorption and desorption of N{sub 2}, FTIR and FTIR-Pyridine, TEM, STEM, EDS, H{sub 2}-TPR, H{sub 2}-adsorption, H{sub 2}-TPD, isopropanol decomposition) and tested in the gas phase hydrogenation of benzene or as carbon materials in the hydrogen storage at room temperature and high pressure. The catalysts prepared exhibited better dispersion and activity than classical catalysts. TOF's of NiAg/SiO{sub 2} or Ni/carbon catalysts were similar to Pt catalysts in benzene hydrogenation. Differences in support acidity or preparation method and presence of Ag as metal additive play a crucial role in the chemical reduction of Ni by hydrazine and in the final properties of the materials. Ni/carbon catalysts could store significant amounts of hydrogen at room temperature and high pressure (0.53%/30 bars), probably through the hydrogen spillover effect. (author)

  13. Catalyst-Directed Diastereoselectivity in Hydrogenative Couplings of Acetylene to α-Chiral Aldehydes: Formal Synthesis of All Eight L-Hexoses

    Science.gov (United States)

    Han, Soo Bong; Kong, Jong Rock; Krische, Michael J.

    2011-01-01

    Hydrogenative coupling of acetylene to α-chiral aldehydes 1a–4a using enantiomeric rhodium catalysts ligated by (S)-MeO-BIPHEP and (R)-MeO-BIPHEP delivers the diastereomeric products of carbonyl-(Z)-butadienylation 1b–4b and 1c–4c, respectively, with good to excellent levels of catalyst directed diastereofacial selectivity. Diastereomeric L-glyceraldehyde acetonide adducts 1b and 1c were converted to the four isomeric enoates 6b, 8b, 6c, and 8c, representing a formal synthesis of all eight L-hexoses. PMID:18729371

  14. Effects of reaction conditions on hydrogen production and carbon nanofiber properties generated by methane decomposition in a fixed bed reactor using a NiCuAl catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Suelves, I.; Pinilla, J.L.; Lazaro, M.J.; Moliner, R. [Instituto de Carboquimica CSIC, Miguel Luesma Castan, 4, 50015 Zaragoza (Spain); Palacios, J.M. [Instituto de Catalisis y Petroleoquimica, CSIC, Cantoblanco, Marie Curie 2, 28049 Madrid (Spain)

    2009-07-01

    In this paper, the results obtained in the catalytic decomposition of methane in a fixed bed reactor using a NiCuAl catalyst prepared by the fusion method are presented. The influences of reaction temperature and space velocity on hydrogen concentration in the outlet gases, as well as on the properties of the carbon produced, have been investigated. Reaction temperature and the space velocity both increase the reaction rate of methane decomposition, but also cause an increase in the rate of catalyst deactivation. Under the operating conditions used, the carbon product is mainly deposited as nanofibers with textural properties highly correlated with the degree of crystallinity. (author)

  15. Production of hydrogen by oxidative reforming of ethanol over Pt catalysts supported on Al{sub 2}O{sub 3} modified with Ce and La

    Energy Technology Data Exchange (ETDEWEB)

    Navarro, R.M.; Alvarez-Galvan, M.C.; Sanchez-Sanchez, M. Cruz; Fierro, J.L.G. [Instituto de Catalisis y Petroleoquimica CSIC, C/Marie Curie s/n. Cantoblanco 28049, Madrid (Spain); Rosa, F. [Centro de Experimentacion de ' El Arenosillo' CEDEA, Instituto Nacional de Tecnica Aeroespacial INTA, Ctra. de San Juan del Puerto-Matalascanas km 31, 21130 Mazagon-Moguer, Huelva (Spain)

    2005-02-25

    A series of Pt catalysts supported on alumina modified by Ce and/or La were prepared and tested in the reaction involving the production of hydrogen by oxidative reforming of ethanol. Characterization of the catalysts by N{sub 2} adsorption, X-ray diffraction, TPR and X-ray photoelectron spectroscopy (XPS) revealed differences in the interaction between platinum and the supports. These differences have important implications in the behaviour of the catalysts for the ethanol-reforming reaction. Ethanol conversion on the Pt/(La)Al{sub 2}O{sub 3} catalyst was found to be close to that of the Pt/Al{sub 2}O{sub 3} catalyst. However, modification of the Al{sub 2}O{sub 3} substrate by ceria led to a more active Pt/(Ce)Al{sub 2}O{sub 3} catalyst. A lower promotion effect was observed when both ceria and lanthana were present on the support substrate. TPR and XPS analyses of ceria-containing samples revealed the existence of a strong interaction between platinum and ceria. This interaction between Pt crystallites at the ceria surface seemed to be responsible for the better performance of the cerium-containing catalysts. It is suggested that the platinum-ceria interaction affects the adsorption-decomposition of ethanol to CH{sub 4} and CO products and their subsequent reforming reactions with steam. When both ceria and lanthana were present on the support substrate the platinum-ceria interaction was diminished, reducing the promoter effect in the production of hydrogen by oxidative reforming of ethanol.

  16. Hydrogen production using zinc-doped carbon nitride catalyst irradiated with visible light

    Directory of Open Access Journals (Sweden)

    Bing Yue, Qiuye Li, Hideo Iwai, Tetsuya Kako and Jinhua Ye

    2011-01-01

    Full Text Available Recently, graphitic carbon nitride (g-C3N4 has been investigated as a photocatalyst for water splitting and organic dye degradation. In this study, we have developed a simple soft-chemical method of doping Zn into g-C3N4 to prepare a metal-containing carbon nitride. The doping was confirmed by x-ray photoelectron spectroscopy, and diffusion reflectance spectra revealed a significant red shift in the absorption edge of Zn/g-C3N4. This hybrid material shows high photocatalytic activity and good stability for hydrogen evolution from an aqueous methanol solution under visible light irradiation (λ≥420 nm. The hydrogen evolution rate was more than 10 times higher for a 10%-Zn/g-C3N4 sample (59.5 μmol h−1 than for pure g-C3N4. The maximum quantum yield was 3.2% at 420 nm.

  17. The Beneficial Effect of Hydrogen on CO Oxidation over Au Catalysts. A Computational Study

    Directory of Open Access Journals (Sweden)

    J. W. Niemantsverdriet

    2011-11-01

    Full Text Available Density functional theory calculations have been carried out to explore the effect of hydrogen on the oxidation of CO in relation to the preferential oxidation of CO in the presence of excess hydrogen (PROX. A range of gold surfaces have been selected including the (100, stepped (310 surfaces and diatomic rows on the (100 surface. These diatomic rows on Au(100 are very efficient in H-H bond scission. O2 hydrogenation strongly enhances the surface-oxygen interaction and assists in scission of the O–O bond. The activation energy required to make the reaction intermediate hydroperoxy (OOH from O2 and H is small. However, we postulate its presence on our Au models as the result of diffusion from oxide supports to the gold surfaces. The OOH on Au in turn opens many low energy cost channels to produce H2O and CO2. CO is selectively oxidized in a H2 atmosphere due to the more favorable reaction barriers while the formation of adsorbed hydroperoxy enhances the reaction rate.

  18. A Review on Bimetallic Nickel-Based Catalysts for CO2 Reforming of Methane.

    Science.gov (United States)

    Bian, Zhoufeng; Das, Sonali; Wai, Ming Hui; Hongmanorom, Plaifa; Kawi, Sibudjing

    2017-11-17

    In recent years, CO2 reforming of methane (dry reforming of methane, DRM) has become an attractive research area because it converts two major greenhouse gasses into syngas (CO and H2 ), which can be directly used as fuel or feedstock for the chemical industry. Ni-based catalysts have been extensively used for DRM because of its low cost and good activity. A major concern with Ni-based catalysts in DRM is severe carbon deposition leading to catalyst deactivation, and a lot of effort has been put into the design and synthesis of stable Ni catalysts with high carbon resistance. One effective and practical strategy is to introduce a second metal to obtain bimetallic Ni-based catalysts. The synergistic effect between Ni and the second metal has been shown to increase the carbon resistance of the catalyst significantly. In this review, a detailed discussion on the development of bimetallic Ni-based catalysts for DRM including nickel alloyed with noble metals (Pt, Ru, Ir etc.) and transition metals (Co, Fe, Cu) is presented. Special emphasis has been provided on the underlying principles that lead to synergistic effects and enhance catalyst performance. Finally, an outlook is presented for the future development of Ni-based bimetallic catalysts. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Poisoning Effect of SO2 on Honeycomb Cordierite-Based Mn–Ce/Al2O3Catalysts for NO Reduction with NH3 at Low Temperature

    Directory of Open Access Journals (Sweden)

    Chengzhi Wang

    2018-01-01

    Full Text Available Honeycomb cordierite-based Mn–Ce/Al2O3 catalysts were prepared by the impregnation method and used for low-temperature selective catalytic reduction (SCR of NOx with NH3, with and without SO2 and/or H2O in a homemade fixed-bed tubular reactor. The catalyst reached nearly 80% NOx conversion at 100 °C in the absence of SO2. However, SO2 reduces the catalytic activity (80% to 72% of the honeycomb cordierite-based Mn–Ce/Al2O3 catalysts under identical conditions. This finding demonstrated that the catalyst exhibited high activity at low temperature and excellent SO2 resistance in the presence of 50 ppm SO2. The fresh and sulfated honeycomb cordierite-based Mn–Ce/Al2O3 catalysts were characterized by scanning electron microscopy (SEM, energy dispersive spectroscopy (EDS, N2 adsorption–desorption, X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, thermogravimetry and differential thermal analysis (TG-DTA, and Fourier transform infrared (FT-IR spectroscopy. Characterization results indicated that the deactivation by SO2 was primarily the result of the deposition of ammonium hydrogen sulfate and sulfated CeO2 on the catalyst surface during the SCR process. The formed sulfates depressed the catalytic activity via the blocking of pores and the occupation of active sites. Additionally, the competitive adsorption between SO2 and NH3 always decreased the catalytic activity.

  20. Production of hydrogen from methanol over Cu/ZnO catalysts promoted by ZrO2 and Al2O3

    NARCIS (Netherlands)

    Navarro, R.M.; Melián-Cabrera, I.; Boutonnet, M.; Birgersson, H.; Agrell, J.; Fierro, J.L.G.

    2003-01-01

    Production of H2 from methanol by steam reforming, partial oxidation, or a combination thereof was studied over Cu/ZnO-based catalysts. The catalysts were characterized by a variety of techniques, including N2O chemisorption, X-ray photoelectron spectroscopy, X-ray diffraction, and