WorldWideScience

Sample records for residual catalyst particles

  1. Mobis HRH process residue hydroconversion using a recoverable nano-catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Romocki, S.; Rhodey, G. [Mobis Energy Inc., Calgary, AB (Canada)

    2009-07-01

    This presentation described a newly developed pseudo-homogeneous catalyst (PHC) for hydroconversion of heavy hydrocarbon feeds with high levels of sulphur, nitrogen, resins, asphaltenes and metals. An active catalyst is formed in the reaction system, consisting of particles that are 2-9 nm in size and whose properties resemble those of a colloid solution at both room and reaction temperature. Residue processing with this pseudo-homogeneous catalyst system results in better cracking and hydrogenation at lower process severity. The PHC system in heavy residue hydroconversion (HRH) process achieves up to 95 per cent residue conversion at pressures below 7.3 MPa, reaction temperatures between 400 to 460 degrees C, and with feed space velocity between 1 to 2 per hour, thus rendering the PHC catalyst system suitable for deep conversion of hydrocarbon residues. As much as 95 per cent of the catalyst can be recovered and regenerated within the process. Pilot plants are in operation for the hydroconversion of Athabasca vacuum bottoms using this technology. The use of the HRH process in oilsands and refinery operations were discussed along with comparative yields and economics. tabs., figs.

  2. Efficient particle filtering through residual nudging

    KAUST Repository

    Luo, Xiaodong

    2013-05-15

    We introduce an auxiliary technique, called residual nudging, to the particle filter to enhance its performance in cases where it performs poorly. The main idea of residual nudging is to monitor and, if necessary, adjust the residual norm of a state estimate in the observation space so that it does not exceed a pre-specified threshold. We suggest a rule to choose the pre-specified threshold, and construct a state estimate accordingly to achieve this objective. Numerical experiments suggest that introducing residual nudging to a particle filter may (substantially) improve its performance, in terms of filter accuracy and/or stability against divergence, especially when the particle filter is implemented with a relatively small number of particles. © 2013 Royal Meteorological Society.

  3. The Immobilization of a Transfer Hydrogenation Catalyst on Colloidal Particles

    NARCIS (Netherlands)

    van Ravensteijn, Bas G P|info:eu-repo/dai/nl/338806008; Schild, Dirk Jan; Kegel, Willem K.|info:eu-repo/dai/nl/113729464; Klein Gebbink, Robertus J M|info:eu-repo/dai/nl/166032646

    2017-01-01

    In this paper, we report a new synthetic procedure to immobilize a transfer hydrogenation catalyst on the surface of colloidal polystyrene particles. Using supports of colloidal dimensions allows for combining a relatively high surface area for catalyst binding, mobility of the catalyst, and facile

  4. Effect of catalyst deactivation on vacuum residue hydrocracking

    Directory of Open Access Journals (Sweden)

    Hoda S. Ahmed

    2013-12-01

    Full Text Available Accelerated deactivation tests of the pre-sulfided Mo–W/SiO2–Al2O3 commercial catalyst were performed using heavy vacuum petroleum feedstock. High reaction temperature employed in the accelerated catalyst aging resulted in large amounts of carbonaceous deposition with high aromaticity, which was found to be the principal deactivation cause. The effect of catalyst deactivation on hydrocracking of vacuum residue was studied. Experiments were carried out in a batch reactor at 60 bar, feed to catalyst ratio 10:1 and temperature 425 °C. The duration time for a cycle-run was 4 h. On increasing the interval duration times from 4 to 20 h (i.e. five cycles, the quality of the hydrocracked products was decreased. In each cycle-run, a fresh feedstock was used with the same sulfide catalyst. The quality of distillate products, such as hydrodesulfurization (HDS was decreased from 61.50% to 39.52%, while asphaltene contents of the total liquid product were increased from 2.7% to 5.2% and their boiling ranges were increased during these duration times due to the successive catalyst deactivation during the 5 cycle-runs, caused by successive adsorption of coke formation.

  5. Automated gunshot residue particle search and characterization.

    Science.gov (United States)

    Tillman, W L

    1987-01-01

    The main disadvantage to gunshot residue (GSR) particle analysis utilizing scanning electron microscope/energy dispersive X-ray (SEM/EDX) instrumentation has been the excessive operator time required for search and identification. This study uses an automated particle search and characterization program for unattended GSR search and identification. This system allows for automatic matrix search, particle sizing, chemical typing, and spectral aquisition with subsequent storage of data to disk for later operator review and verification. This work describes various aspects of the program, determines appropriate parameters adequate for both unique and characteristic GSR particle identification, and evaluates the reliability of data obtained. Samples are collected via the tape lift method from test-firings of .38, .32, .25, and .22 caliber handguns at time after firing intervals of 0 to 6 h. Unique GSR particles are consistently and correctly identified by this method on tape lift samples taken up to 4 h after firing. False positive results of unique GSR particles are not encountered on control handblank samples. This technique appears to provide the forensic science community with an operator-free method of reliable GSR particle search and an improved analyst-time-per-case ratio.

  6. Asymptotic stability of a catalyst particle

    DEFF Research Database (Denmark)

    Wedel, Stig; Michelsen, Michael L.; Villadsen, John

    1977-01-01

    The catalyst asymptotic stability problem is studied by means of several new methods that allow accurate solutions to be calculated where other methods have given qualitatively erroneous results. The underlying eigenvalue problem is considered in three limiting situations Le = ∞, 1 and 0. These a......The catalyst asymptotic stability problem is studied by means of several new methods that allow accurate solutions to be calculated where other methods have given qualitatively erroneous results. The underlying eigenvalue problem is considered in three limiting situations Le = ∞, 1 and 0...

  7. Catalyst Particles for Fluid Catalytic Cracking Visualized at the Individual Particle Level by Micro-Spectroscopy

    NARCIS (Netherlands)

    Buurmans, I.L.C.

    2011-01-01

    In this PhD research the investigation of the reactivity and acidity of Fluid Catalytic Cracking (FCC) catalysts at the level of an individual catalyst particles is described. A range of micro-spectroscopic techniques has been applied to visualize both the active zeolite component within the

  8. Comprehensive Utilization of Filter Residue from the Preparation Process of Zeolite-Based Catalysts

    Directory of Open Access Journals (Sweden)

    Shu-Qin Zheng

    2016-05-01

    Full Text Available A novel utilization method of filter residue from the preparation process of zeolite-based catalysts was investigated. Y zeolite and a fluid catalytic cracking (FCC catalyst were synthesized from filter residue. Compared to the Y zeolite synthesized by the conventional method, the Y zeolite synthesized from filter residue exhibited better thermal stability. The catalyst possessed wide-pore distribution. In addition, the pore volume, specific surface area, attrition resistance were superior to those of the reference catalyst. The yields of gasoline and light oil increased by 1.93 and 1.48 %, respectively. At the same time, the coke yield decreased by 0.41 %. The catalyst exhibited better gasoline and coke selectivity. The quality of the cracked gasoline had been improved.

  9. Particle methods of characterising catalysts Part 1

    International Nuclear Information System (INIS)

    Wright, C.J.

    1980-01-01

    It is the intention of this chapter to explain and illustrate the areas in catalysis research where advantages will accrue from using neutron techniques to illuminate a particular problem. The introduction will include an outline of the different classes of neutron experiment and a description of how the neutron nucleus interaction expressed through the cross-sections leads to many of the individual applications. After this the technique will be described area by area, with examples chosen from the literature to underscore points of importance. The areas are: small angle scattering, where information on the textural properties of materials such as pore structure and particle size can be determined; diffraction, for structure analysis; quasi-elastic scattering, for characterising the spatial and temporal aspects of atomic and molecular diffusion; and inelastic scattering, for studying vibrational transitions of atoms and molecules. (author)

  10. Improved steam gasification of lignocellulosic residues in a fluidized bed with commercial steam reforming catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Aznar, M.P.; Corella, J.; Delgado, J.; Lahoz, J. (Univ. of Zaragoza (Spain))

    1993-01-01

    The improved/two-stage steam gasification of biomass or lignocellulosic residues in fluidized bed with steam reforming catalysts placed in a downstream secondary reactor has been studied. Two commercial catalysts, R-67 and RKS-1 from Topsoee, were used at their incipient fluidization conditions. At 720-760 C and space-times of only 0.10-0.20 s, with catalyst sizes under 1.0 mm and with steam/biomass ratios of 1.2-1.6, tar conversions of 99.95% were achieved in the catalytic reactor. In this process, tar and methane in the flue gas can be easily lowered below 5 mg/m[sup 3](NTP) and 0.5 vol %, respectively, without using oxygen. The catalyst deactivation by coke from the tar cracking is the main problem of this process.

  11. Nanoscale Chemical Imaging of an Individual Catalyst Particle with Soft X-ray Ptychography

    NARCIS (Netherlands)

    Wise, Anna M.; Weker, Johanna Nelson; Kalirai, Samanbir; Farmand, Maryam; Shapiro, David A.; Meirer, Florian; Weckhuysen, Bert M.|info:eu-repo/dai/nl/285484397

    2016-01-01

    Understanding Fe deposition in fluid catalytic cracking (FCC) catalysis is critical for the mitigation of catalyst degradation. Here we employ soft X-ray ptychography to determine at the nanoscale the distribution and chemical state of Fe in an aged FCC catalyst particle. We show that both particle

  12. Origin of residual particles on transferred graphene grown by CVD

    Science.gov (United States)

    Yasunishi, Tomohiro; Takabayashi, Yuya; Kishimoto, Shigeru; Kitaura, Ryo; Shinohara, Hisanori; Ohno, Yutaka

    2016-08-01

    Large-area single-layer graphene can be grown on Cu foil by CVD, but for device applications, the layer must to be transferred onto an insulating substrate. As residual particles are often observed on transferred graphene, we investigated their origin using scanning electron microscopy and energy-dispersive X-ray spectrometry (EDX). The results show that these residual particles are composed either of silicon or an alloy of a few metals, and hence, likely originate from the quartz tube of the CVD furnace and the impurities contained in the Cu foil.

  13. Revealing the Cytotoxicity of Residues of Phosphazene Catalysts Used for Synthesis of Poly(ethylene oxide)

    KAUST Repository

    Xia, Yening

    2017-08-24

    We herein report a case study on the toxicity of residual catalyst in metal-free polymer. Eight-arm star-like poly(ethylene oxide)s were successfully synthesized via phosphazene-catalyzed ring-opening polymerization of ethylene oxide using sucrose as an octahydroxy initiator. The products were subjected to MTT assay using human cancer cell lines (MDA-MB-231 and A2780). Comparison between the crude and purified products clearly revealed that the residual phosphazenium salts were considerably cytotoxic regardless of the anionic species, and that the cytotoxicity of more bulky t-BuP4 salt was higher than that of t-BuP2 salt. Such results have therefore put forward the necessity for removal of the catalyst residues from PEO-based polymers synthesized through phosphazene catalysis for bio-related applications, and for the development of less or non-toxic organocatalysts for such polymers.

  14. The Dependence of CNT Aerogel Synthesis on Sulfur-driven Catalyst Nucleation Processes and a Critical Catalyst Particle Mass Concentration.

    Science.gov (United States)

    Hoecker, Christian; Smail, Fiona; Pick, Martin; Weller, Lee; Boies, Adam M

    2017-11-06

    The floating catalyst chemical vapor deposition (FC-CVD) process permits macro-scale assembly of nanoscale materials, enabling continuous production of carbon nanotube (CNT) aerogels. Despite the intensive research in the field, fundamental uncertainties remain regarding how catalyst particle dynamics within the system influence the CNT aerogel formation, thus limiting effective scale-up. While aerogel formation in FC-CVD reactors requires a catalyst (typically iron, Fe) and a promotor (typically sulfur, S), their synergistic roles are not fully understood. This paper presents a paradigm shift in the understanding of the role of S in the process with new experimental studies identifying that S lowers the nucleation barrier of the catalyst nanoparticles. Furthermore, CNT aerogel formation requires a critical threshold of Fe x C y  > 160 mg/m 3 , but is surprisingly independent of the initial catalyst diameter or number concentration. The robustness of the critical catalyst mass concentration principle is proved further by producing CNTs using alternative catalyst systems; Fe nanoparticles from a plasma spark generator and cobaltocene and nickelocene precursors. This finding provides evidence that low-cost and high throughput CNT aerogel routes may be achieved by decoupled and enhanced catalyst production and control, opening up new possibilities for large-scale CNT synthesis.

  15. Colloidal polymer particles as catalyst carriers and phase transfer agents in multiphasic hydroformylation reactions.

    Science.gov (United States)

    Peral, D; Stehl, D; Bibouche, B; Yu, H; Mardoukh, J; Schomäcker, R; Klitzing, R von; Vogt, D

    2018-03-01

    Colloidal particles have been used to covalently bind ligands for the heterogenization of homogeneous catalysts. The replacement of the covalent bonds by electrostatic interactions between particles and the catalyst could preserve the selectivity of a truly homogeneous catalytic process. Functionalized polymer particles with trimethylammonium moieties, dispersed in water, with a hydrophobic core and a hydrophilic shell have been synthesized by emulsion polymerization and have been thoroughly characterized. The ability of the particles with different monomer compositions to act as catalyst carriers has been studied. Finally, the colloidal dispersions have been applied as phase transfer agents in the multiphasic rhodium-catalyzed hydroformylation of 1-octene. The hydrodynamic radius of the particles has been shown to be around 100 nm, and a core-shell structure could be observed by atomic force microscopy. The polymer particles were proven to act as carriers for the water-soluble hydroformylation catalyst, due to electrostatic interaction between the functionalized particles bearing ammonium groups and the sulfonated ligands of the catalyst. The particles were stable under the hydroformylation conditions and the aqueous catalyst phase could be recycled three times. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Edge termination of MoS2 and CoMoS catalyst particles

    DEFF Research Database (Denmark)

    Byskov, Line Sjolte; Nørskov, Jens Kehlet; Clausen, B. S.

    2000-01-01

    The edge termination of MoS2 and CoMoS catalyst particles is studied by density functional calculations. We show that for structures without vacancies Mo-terminated edges have the lowest edge energies. Creation of vacancies, which are believed to be active sites in these catalyst systems, leads...

  17. Staining of fluid-catalytic cracking catalysts: Localising Brønsted acidity within a single catalyst particle

    NARCIS (Netherlands)

    Buurmans, I.L.C.|info:eu-repo/dai/nl/31406592X; Ruiz Martinez, J.|info:eu-repo/dai/nl/341386405; van Leeuwen, S.L.; van der Beek, D.; Bergwerff, J.A.; Knowles, W.V.; Vogt, Eelco|info:eu-repo/dai/nl/073717398; Weckhuysen, B.M.|info:eu-repo/dai/nl/285484397

    2012-01-01

    A time-resolved in situ micro-spectroscopic approach has been used to investigate the Brønsted acidic properties of fluid-catalytic-cracking (FCC) catalysts at the single particle level by applying the acid-catalysed styrene oligomerisation probe reaction. The reactivity of individual FCC components

  18. Separation of Fischer-Tropsch Wax Products from Ultrafine Iron Catalyst Particles

    Energy Technology Data Exchange (ETDEWEB)

    Amitava Sarkar; James K. Neathery; Burtron H. Davis

    2006-12-31

    A fundamental filtration study was started to investigate the separation of Fischer-Tropsch Synthesis (FTS) liquids from iron-based catalyst particles. Slurry-phase FTS in slurry bubble column reactor systems is the preferred mode of operation since the reaction is highly exothermic. Consequently, heavy wax products in one approach may be separated from catalyst particles before being removed from the reactor system. Achieving an efficient wax product separation from iron-based catalysts is one of the most challenging technical problems associated with slurry-phase iron-based FTS and is a key factor for optimizing operating costs. The separation problem is further compounded by attrition of iron catalyst particles and the formation of ultra-fine particles.

  19. SEPARATION OF FISCHER-TROPSCH WAX PRODUCTS FROM ULTRAFINE IRON CATALYST PARTICLES

    Energy Technology Data Exchange (ETDEWEB)

    James K. Neathery; Gary Jacobs; Burtron H. Davis

    2004-09-30

    In this reporting period, a fundamental filtration study was continued to investigate the separation of Fischer-Tropsch Synthesis (FTS) liquids from iron-based catalyst particles. The overall focus of the program is with slurry-phase FTS in slurry bubble column reactor systems. Hydrocarbon products must be separated from catalyst particles before being removed from the reactor system. An efficient wax product/catalyst separation system is a key factor for optimizing operating costs for iron-based slurry-phase FTS. Previous work has focused on catalyst particle attrition and the formation of ultra-fine iron carbide and/or carbon particles. With the current study, we are investigating how the filtration properties are affected by these chemical and physical changes of the catalyst slurry during activation/synthesis. The shakedown phase of the pilot-scale filtration platform was completed at the end of the last reporting period. A study of various molecular weight waxes was initiated to determine the effect of wax physical properties on the permeation rate without catalyst present. As expected, the permeation flux was inversely proportional to the nominal average molecular weight of the polyethylene wax. Even without catalyst particles present in the filtrate, the filtration membranes experience fouling during an induction period on the order of days on-line. Another long-term filtration test was initiated using a batch of iron catalyst that was previously activated with CO to form iron carbide in a separate continuous stirred tank reactor (CSTR) system. The permeation flux stabilized more rapidly than that experienced with unactivated catalyst tests.

  20. Separation of Fischer-Tropsch Wax Products from Ultrafine Iron Catalyst Particles

    Energy Technology Data Exchange (ETDEWEB)

    James K. Neathery; Gary Jacobs; Amitava Sarkar; Burtron H. Davis

    2005-09-30

    In this reporting period, a study of ultra-fine iron catalyst filtration was initiated to study the behavior of ultra-fine particles during the separation of Fischer-Tropsch Synthesis (FTS) liquids filtration. The overall focus of the program is with slurry-phase FTS in slurry bubble column reactor systems. Hydrocarbon products must be separated from catalyst particles before being removed from the reactor system. An efficient wax product/catalyst separation system is a key factor for optimizing operating costs for iron-based slurry-phase FTS. Previous work has focused on catalyst particle attrition and the formation of ultra-fine iron carbide and/or carbon particles. With the current study, we are investigating how the filtration properties are affected by these chemical and physical changes of the catalyst slurry during activation/synthesis. The change of particle size during the slurry-phase FTS has monitored by withdrawing catalyst sample at different TOS. The measurement of dimension of the HRTEM images of samples showed a tremendous growth of the particles. Carbon rims of thickness 3-6 nm around the particles were observed. This growth in particle size was not due to carbon deposition on the catalyst. A conceptual design and operating philosophy was developed for an integrated wax filtration system for a 4 liter slurry bubble column reactor to be used in Phase II of this research program. The system will utilize a primary inertial hydroclone followed by a Pall Accusep cross-flow membrane. Provisions for cleaned permeate back-pulsing will be included to as a flux maintenance measure.

  1. "Hairy" Poly(3-hexylthiophene) Particles Prepared via Surface-Initiated Kumada Catalyst-Transfer Polycondensation

    DEFF Research Database (Denmark)

    Senkovskyy, Volodymyr; Tkachov, Roman; Beryozkina, Tetyana

    2009-01-01

    electronics, was selectively grown by SI-KCTP from (nano)particles bearing surface-immobilized Ni catalysts supported by bidentate phosphorus ligands, that resulted in hairy (nano)particles with end-tethered P3HT chains. Densely grafted P3HT chains exhibit strongly altered optical properties compared...

  2. Structure and acidity of individual Fluid Catalytic Cracking catalyst particles studied by synchrotron-based infrared micro-spectroscopy

    NARCIS (Netherlands)

    Buurmans, I.L.C.|info:eu-repo/dai/nl/31406592X; Soulimani, F.|info:eu-repo/dai/nl/313889449; Ruiz Martinez, J.|info:eu-repo/dai/nl/341386405; van der Bij, H.E.|info:eu-repo/dai/nl/328201294; Weckhuysen, B.M.|info:eu-repo/dai/nl/285484397

    2013-01-01

    A synchrotron-based infrared micro-spectroscopy study has been conducted to investigate the structure as well as the Brønsted and Lewis acidity of Fluid Catalytic Cracking (FCC) catalyst particles at the individual particle level. Both fresh and laboratory-deactivated catalyst particles have been

  3. Adsorptive removal of residual catalyst from palm biodiesel: Application of response surface methodology

    Directory of Open Access Journals (Sweden)

    Mjalli Sabri Farouq

    2012-01-01

    Full Text Available In this work, the residual potassium hydroxide catalyst was removed from palm oil-based methyl esters using an adsorption technique. The produced biodiesel was initially purified through a water washing process. To produce a biodiesel with a better quality and also to meet standard specifications (EN 14214 and ASTM D6751, batch adsorption on palm shell activated carbon was used for further catalyst removal. The Central Composite Design (CCD of the Response Surface Methodology (RSM was used to study the influence of adsorbent amount, time and temperature on the adsorption of potassium species. The maximum catalyst removal was achieved at 40°C using 0.9 g activated carbon for 20 h adsorption time. The results from the Response Surface Methodology are in a good agreement with the measured values. The absolute error in prediction at the optimum condition was 3.7%, which is reasonably accurate. This study proves that adsorption post-treatment techniques can be successfully employed to improve the quality of biodiesel fuel for its effective use on diesel engines and to minimize the usage of water.

  4. Particle size effects for carbon nanofiber supported platinum and ruthenium catalysts for the selective hydrogenation of cinnamaldehyde

    NARCIS (Netherlands)

    Plomp, A.J.; Vuori, H.; Krause, A.O.I.; de Jong, K.P.; Bitter, J.H.

    2008-01-01

    The selective hydrogenation of cinnamaldehyde was studied over carbon nanofibers (CNF) supported platinum and ruthenium catalysts. The catalysts differed independently in their metal particle sizes and amount of acidic oxygen groups on the CNF surface. For the catalysts with oxygen on the CNF

  5. Preparation and particle size effects of Ag/Α-Al2O3 catalysts for ethylene epoxidation

    NARCIS (Netherlands)

    van den Reijen, J. E.; Kanungo, S.; Welling, T. A.J.; Versluijs-Helder, M.; Nijhuis, T.A.; de Jong, K. P.; de Jongh, P. E.

    2017-01-01

    Currently, for the industrial ethylene epoxidation α-alumina supported silver catalysts are the only catalyst of choice. We demonstrate a novel method to produce these catalysts with different silver particle sizes, but without changing other key parameters that may affect the catalytic performance

  6. Effect of Particle Size and Operating Conditions on Pt3Co PEMFC Cathode Catalyst Durability

    Directory of Open Access Journals (Sweden)

    Mallika Gummalla

    2015-05-01

    Full Text Available The initial performance and decay trends of polymer electrolyte membrane fuel cells (PEMFC cathodes with Pt3Co catalysts of three mean particle sizes (4.9 nm, 8.1 nm, and 14.8 nm with identical Pt loadings are compared. Even though the cathode based on 4.9 nm catalyst exhibited the highest initial electrochemical surface area (ECA and mass activity, the cathode based on 8.1 nm catalyst showed better initial performance at high currents. Owing to the low mass activity of the large particles, the initial performance of the 14.8 nm Pt3Co-based electrode was the lowest. The performance decay rate of the electrodes with the smallest Pt3Co particle size was the highest and that of the largest Pt3Co particle size was lowest. Interestingly, with increasing number of decay cycles (0.6 to 1.0 V, 50 mV/s, the relative improvement in performance of the cathode based on 8.1 nm Pt3Co over the 4.9 nm Pt3Co increased, owing to better stability of the 8.1 nm catalyst. The electron microprobe analysis (EMPA of the decayed membrane-electrode assembly (MEA showed that the amount of Co in the membrane was lower for the larger particles, and the platinum loss into the membrane also decreased with increasing particle size. This suggests that the higher initial performance at high currents with 8.1 nm Pt3Co could be due to lower contamination of the ionomer in the electrode. Furthermore, lower loss of Co from the catalyst with increased particle size could be one of the factors contributing to the stability of ECA and mass activity of electrodes with larger cathode catalyst particles. To delineate the impact of particle size and alloy effects, these results are compared with prior work from our research group on size effects of pure platinum catalysts. The impact of PEMFC operating conditions, including upper potential, relative humidity, and temperature on the alloy catalyst decay trends, along with the EMPA analysis of the decayed MEAs, are reported.

  7. Single-particle characterization of ice-nucleating particles and ice particles residuals sampled by three different techniques

    Science.gov (United States)

    Kandler, Konrad; Worringen, Annette; Benker, Nathalie; Dirsch, Thomas; Mertes, Stephan; Schenk, Ludwig; Kästner, Udo; Frank, Fabian; Nillius, Björn; Bundke, Ulrich; Rose, Diana; Curtius, Joachim; Kupiszewski, Piotr; Weingartner, Ernest; Vochezer, Paul; Schneider, Johannes; Schmidt, Susan; Weinbruch, Stephan; Ebert, Martin

    2015-04-01

    During January/February 2013, at the High Alpine Research Station Jungfraujoch a measurement campaign was carried out, which was centered on atmospheric ice-nucleating particles (INP) and ice particle residuals (IPR). Three different techniques for separation of INP and IPR from the non-ice-active particles are compared. The Ice Selective Inlet (ISI) and the Ice Counterflow Virtual Impactor (Ice-CVI) sample ice particles from mixed phase clouds and allow for the analysis of the residuals. The combination of the Fast Ice Nucleus Chamber (FINCH) and the Ice Nuclei Pumped Counterflow Virtual Impactor (IN-PCVI) provides ice-activating conditions to aerosol particles and extracts the activated INP for analysis. Collected particles were analyzed by scanning electron microscopy and energy-dispersive X-ray microanalysis to determine size, chemical composition and mixing state. All INP/IPR-separating techniques had considerable abundances (median 20 - 70 %) of instrumental contamination artifacts (ISI: Si-O spheres, probably calibration aerosol; Ice-CVI: Al-O particles; FINCH+IN-PCVI: steel particles). Also, potential sampling artifacts (e.g., pure soluble material) occurred with a median abundance of metal oxides were the major INP/IPR particle types separated by all three techniques. Soot was a minor contributor. Lead was detected in less than 10 % of the particles, of which the majority were internal mixtures with other particle types. Sea-salt and sulfates were identified by all three methods as INP/IPR. Most samples showed a maximum of the INP/IPR size distribution at 400 nm geometric diameter. In a few cases, a second super-micron maximum was identified. Soot/carbonaceous material and metal oxides were present mainly in the submicron range. ISI and FINCH yielded silicates and Ca-rich particles mainly with diameters above 1 µm, while the Ice-CVI also separated many submicron IPR. As strictly parallel sampling could not be performed, a part of the discrepancies between

  8. Advances in X-ray Chemical Imaging of a Single Catalyst Particle

    NARCIS (Netherlands)

    Kalirai, S.

    2016-01-01

    Fluid Catalytic Cracking (FCC) catalyst particles are complex, hierarchical, multi-component systems that are used ubiquitously for the production of valuable hydrocarbons such as gasoline and propylene from crude oil feedstocks. In the FCC unit, high heat, steam and feedstocks contaminated with

  9. Dispersion and Orientation of Zeolite ZSM-5 Crystallites within a Fluid Catalytic Cracking Catalyst Particle

    NARCIS (Netherlands)

    Sprung, Christoph; Weckhuysen, Bert M.

    2014-01-01

    Confocal fluorescence microscopy was employed to selectively visualize the dispersion and orientation of zeolite ZSM-5 domains inside a single industrially applied fluid catalytic cracking (FCC) catalyst particle. Large ZSM-5 crystals served as a model system together with the acid-catalyzed

  10. Performance under sulfate attack of concrete additioned with fluid catalytic cracking catalyst residue (FCC and metakaolin (MK

    Directory of Open Access Journals (Sweden)

    Nancy Torres Castellanos

    2013-01-01

    Full Text Available In this work the evaluation of the performance of concrete added with Fluid Catalytic Cracking Catalyst residue (FCC from a Colombian petroleum company, under sulfate attack, is presented. The results of this concrete are compared with the results of Metakaolin (MK added concrete. The analysis of the pozzolanic materials included the determination of the particle size, the pozzolanic activity and the chemical and mineralogical composition. Different percentages of FCC were used as Portland cement replacement in proportions of 0, 10, 20 and 30%; similarly concrete added with 20% of MK as replacement was elaborated. Compressive strength and performance under sulfate attack were evaluated. Results showed that concrete with FCC and MK as well as control concrete had similar behavior; however its expansion was higher. In addition, the performance of the two types of concrete (FCC y MK under sulfate attack was comparable; this could be due to fact that FCC and MK showed similarities regarding of their chemical and mineralogical composition. Importantly, after 360 days of exposure the specimens with MK and FCC showed no significant deterioration.

  11. Pt based PEMFC catalysts prepared from colloidal particle suspensions--a toolbox for model studies.

    Science.gov (United States)

    Speder, Jozsef; Altmann, Lena; Roefzaad, Melanie; Bäumer, Marcus; Kirkensgaard, Jacob J K; Mortensen, Kell; Arenz, Matthias

    2013-03-14

    A colloidal synthesis approach is presented that allows systematic studies of the properties of supported proton exchange membrane fuel cell (PEMFC) catalysts. The applied synthesis route is based on the preparation of monodisperse nanoparticles in the absence of strong binding organic stabilizing agents. No temperature post-treatment of the catalyst is required rendering the synthesis route ideally suitable for comparative studies. We report work concerning a series of catalysts based on the same colloidal Pt nanoparticle (NP) suspension, but with different high surface area (HSA) carbon supports. It is shown that for the prepared catalysts the carbon support has no catalytic co-function, but carbon pre-treatment leads to enhanced sticking of the Pt NPs on the support. An unwanted side effect, however, is NP agglomeration during synthesis. By contrast, enhanced NP sticking without agglomeration can be accomplished by the addition of an ionomer to the NP suspension. The catalytic activity of the prepared catalysts for the oxygen reduction reaction is comparable to industrial catalysts and no influence of the particle size is found in the range of 2-5 nm.

  12. Single-particle characterization of ice-nucleating particles and ice particle residuals sampled by three different techniques

    Science.gov (United States)

    Worringen, A.; Kandler, K.; Benker, N.; Dirsch, T.; Mertes, S.; Schenk, L.; Kästner, U.; Frank, F.; Nillius, B.; Bundke, U.; Rose, D.; Curtius, J.; Kupiszewski, P.; Weingartner, E.; Vochezer, P.; Schneider, J.; Schmidt, S.; Weinbruch, S.; Ebert, M.

    2015-04-01

    In the present work, three different techniques to separate ice-nucleating particles (INPs) as well as ice particle residuals (IPRs) from non-ice-active particles are compared. The Ice Selective Inlet (ISI) and the Ice Counterflow Virtual Impactor (Ice-CVI) sample ice particles from mixed-phase clouds and allow after evaporation in the instrument for the analysis of the residuals. The Fast Ice Nucleus Chamber (FINCH) coupled with the Ice Nuclei Pumped Counterflow Virtual Impactor (IN-PCVI) provides ice-activating conditions to aerosol particles and extracts the activated particles for analysis. The instruments were run during a joint field campaign which took place in January and February 2013 at the High Alpine Research Station Jungfraujoch (Switzerland). INPs and IPRs were analyzed offline by scanning electron microscopy and energy-dispersive X-ray microanalysis to determine their size, chemical composition and mixing state. Online analysis of the size and chemical composition of INP activated in FINCH was performed by laser ablation mass spectrometry. With all three INP/IPR separation techniques high abundances (median 20-70%) of instrumental contamination artifacts were observed (ISI: Si-O spheres, probably calibration aerosol; Ice-CVI: Al-O particles; FINCH + IN-PCVI: steel particles). After removal of the instrumental contamination particles, silicates, Ca-rich particles, carbonaceous material and metal oxides were the major INP/IPR particle types obtained by all three techniques. In addition, considerable amounts (median abundance mostly a few percent) of soluble material (e.g., sea salt, sulfates) were observed. As these soluble particles are often not expected to act as INP/IPR, we consider them as potential measurement artifacts. Minor types of INP/IPR include soot and Pb-bearing particles. The Pb-bearing particles are mainly present as an internal mixture with other particle types. Most samples showed a maximum of the INP/IPR size distribution at 200

  13. Oblate hemispheroidal Large Ruthenium Particles Supported on Calcium Amide as Efficient Catalysts for Ammonia Decomposition.

    Science.gov (United States)

    Kishida, Kazuhisa; Kitano, Masaaki; Inoue, Yasunori; Sasase, Masato; Nakao, Takuya; Tada, Tomofumi; Abe, Hitoshi; Niwa, Yasuhiro; Yokoyama, Toshiharu; Hara, Michikazu; Hosono, Hideo

    2018-03-30

    Ammonia decomposition is positioned as an important technology for abstracting hydrogen from ammonia toward the realization of a hydrogen economy. Here, we report that oblate hemispheroidal large Ru particles on Ca(NH₂)₂ function as efficient catalysts for ammonia decomposition. The turnover frequency (TOF) of Ru/Ca(NH₂)₂ increased by two orders of magnitude as the Ru particle size was increased from 1.5 to 8.4 nm. More than 90% ammonia decomposition was achieved over Ru/Ca(NH₂)₂ with oblate hemispheroidal large Ru particles at 360 ºC, which is comparable to that of alkali-promoted Ru catalysts with small Ru particle sizes. XAFS analyses revealed that Ru particles are immobilized on Ca(NH₂)₂ by Ru-N bonding formed at the metal-support interface, which leads to oblate hemispheroidal Ru particles. Such a strong metal-support interaction in the Ru/Ca(NH₂)₂ is also substantiated by density functional theory calculations. The high activity of Ru/Ca(NH₂)₂ with large Ru particles primarily originates from the shape and appropriate size of Ru particles with a high density of active sites rather than the electron-donating ability of Ca(NH₂)₂. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Revealing the Cytotoxicity of Residues of Phosphazene Catalysts Used for the Synthesis of Poly(ethylene oxide).

    Science.gov (United States)

    Xia, Yening; Shen, Jizhou; Alamri, Haleema; Hadjichristidis, Nikos; Zhao, Junpeng; Wang, Yucai; Zhang, Guangzhao

    2017-10-09

    We herein report a case study on the toxicity of residual catalyst in metal-free polymer. Eight-arm star-like poly(ethylene oxide)s were successfully synthesized via phosphazene-catalyzed ring-opening polymerization of ethylene oxide using sucrose as an octahydroxy initiator. The products were subjected to MTT assay using human cancer cell lines (MDA-MB-231 and A2780). Comparison between the crude and purified products clearly revealed that the residual phosphazenium salts were considerably cytotoxic, regardless of the anionic species, and that the cytotoxicity of more bulky t-BuP 4 salt was higher than that of t-BuP 2 salt. Such results have therefore put forward the necessity for removal of the catalyst residues from PEO-based polymers synthesized through phosphazene catalysis for biorelated applications and for the development of less or nontoxic organocatalysts for such polymers.

  15. Bubbling bed catalytic hydropyrolysis process utilizing larger catalyst particles and smaller biomass particles featuring an anti-slugging reactor

    Science.gov (United States)

    Marker, Terry L; Felix, Larry G; Linck, Martin B; Roberts, Michael J

    2014-09-23

    This invention relates to a process for thermochemically transforming biomass or other oxygenated feedstocks into high quality liquid hydrocarbon fuels. In particular, a catalytic hydropyrolysis reactor, containing a deep bed of fluidized catalyst particles is utilized to accept particles of biomass or other oxygenated feedstocks that are significantly smaller than the particles of catalyst in the fluidized bed. The reactor features an insert or other structure disposed within the reactor vessel that inhibits slugging of the bed and thereby minimizes attrition of the catalyst. Within the bed, the biomass feedstock is converted into a vapor-phase product, containing hydrocarbon molecules and other process vapors, and an entrained solid char product, which is separated from the vapor stream after the vapor stream has been exhausted from the top of the reactor. When the product vapor stream is cooled to ambient temperatures, a significant proportion of the hydrocarbons in the product vapor stream can be recovered as a liquid stream of hydrophobic hydrocarbons, with properties consistent with those of gasoline, kerosene, and diesel fuel. Separate streams of gasoline, kerosene, and diesel fuel may also be obtained, either via selective condensation of each type of fuel, or via later distillation of the combined hydrocarbon liquid.

  16. Bubbling bed catalytic hydropyrolysis process utilizinig larger catalyst particles and small biomass particles featuring an anti-slugging reactor

    Science.gov (United States)

    Marker, Terry L.; Felix, Larry G.; Linck, Martin B.; Roberts, Michael J.

    2016-12-06

    This invention relates to a process for thermochemically transforming biomass or other oxygenated feedstocks into high quality liquid hydrocarbon fuels. In particular, a catalytic hydropyrolysis reactor, containing a deep bed of fluidized catalyst particles is utilized to accept particles of biomass or other oxygenated feedstocks that are significantly smaller than the particles of catalyst in the fluidized bed. The reactor features an insert or other structure disposed within the reactor vessel that inhibits slugging of the bed and thereby minimizes attrition of the catalyst. Within the bed, the biomass feedstock is converted into a vapor-phase product, containing hydrocarbon molecules and other process vapors, and an entrained solid char product, which is separated from the vapor stream after the vapor stream has been exhausted from the top of the reactor. When the product vapor stream is cooled to ambient temperatures, a significant proportion of the hydrocarbons in the product vapor stream can be recovered as a liquid stream of hydrophobic hydrocarbons, with properties consistent with those of gasoline, kerosene, and diesel fuel. Separate streams of gasoline, kerosene, and diesel fuel may also be obtained, either via selective condensation of each type of fuel, or via later distillation of the combined hydrocarbon liquid.

  17. Characterisation of gunshot residue particles using self-consistent ion beam analysis

    Energy Technology Data Exchange (ETDEWEB)

    Bailey, M.J. [University of Surrey Ion Beam Centre, Guildford, GU2 7XH (United Kingdom)], E-mail: m.bailey@surrey.ac.uk; Jeynes, C. [University of Surrey Ion Beam Centre, Guildford, GU2 7XH (United Kingdom)

    2009-06-15

    Individual particles of gunshot residue were studied with particle-induced X-ray emission and backscattering spectrometry using a 2.5 MeV H{sup +} beam focussed to {approx}4 {mu}m and self-consistent fitting of the data. The geometry of these spherical particles was considered in order to accurately fit the corresponding particle spectrum and therefore to quantify the trace element composition of these particles. The demonstrable self-consistency of this method allows the compositions of most residue particles to be determined unambiguously and with a higher sensitivity to trace elements than conventional methods.

  18. In situ chemical composition measurement of individual cloud residue particles at a mountain site, southern China

    Science.gov (United States)

    Lin, Qinhao; Zhang, Guohua; Peng, Long; Bi, Xinhui; Wang, Xinming; Brechtel, Fred J.; Li, Mei; Chen, Duohong; Peng, Ping'an; Sheng, Guoying; Zhou, Zhen

    2017-07-01

    To investigate how atmospheric aerosol particles interact with chemical composition of cloud droplets, a ground-based counterflow virtual impactor (GCVI) coupled with a real-time single-particle aerosol mass spectrometer (SPAMS) was used to assess the chemical composition and mixing state of individual cloud residue particles in the Nanling Mountains (1690 m a. s. l. ), southern China, in January 2016. The cloud residues were classified into nine particle types: aged elemental carbon (EC), potassium-rich (K-rich), amine, dust, Pb, Fe, organic carbon (OC), sodium-rich (Na-rich) and Other. The largest fraction of the total cloud residues was the aged EC type (49.3 %), followed by the K-rich type (33.9 %). Abundant aged EC cloud residues that mixed internally with inorganic salts were found in air masses from northerly polluted areas. The number fraction (NF) of the K-rich cloud residues increased within southwesterly air masses from fire activities in Southeast Asia. When air masses changed from northerly polluted areas to southwesterly ocean and livestock areas, the amine particles increased from 0.2 to 15.1 % of the total cloud residues. The dust, Fe, Pb, Na-rich and OC particle types had a low contribution (0.5-4.1 %) to the total cloud residues. Higher fraction of nitrate (88-89 %) was found in the dust and Na-rich cloud residues relative to sulfate (41-42 %) and ammonium (15-23 %). Higher intensity of nitrate was found in the cloud residues relative to the ambient particles. Compared with nonactivated particles, nitrate intensity decreased in all cloud residues except for dust type. To our knowledge, this study is the first report on in situ observation of the chemical composition and mixing state of individual cloud residue particles in China.

  19. Single Atomic Iron Catalysts for Oxygen Reduction in Acidic Media: Particle Size Control and Thermal Activation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hanguang [Department; Hwang, Sooyeon [Center; Wang, Maoyu [School; Feng, Zhenxing [School; Karakalos, Stavros [Department; Luo, Langli [Pacific Northwest National Laboratory, Richland, Washington 99352, United States; Qiao, Zhi [Department; Xie, Xiaohong [Pacific Northwest National Laboratory, Richland, Washington 99352, United States; Wang, Chongmin [Pacific Northwest National Laboratory, Richland, Washington 99352, United States; Su, Dong [Center; Shao, Yuyan [Pacific Northwest National Laboratory, Richland, Washington 99352, United States; Wu, Gang [Department

    2017-09-26

    To significantly reduce the cost of proton exchange membrane (PEM) fuel cells, current Pt must be replaced by platinum-metal-group (PGM)-free catalysts for the oxygen reduction reaction (ORR) in acid. We report here a new class of high-performance atomic iron dispersed carbon catalysts through controlled chemical doping of iron ions into zinc-zeolitic imidazolate framework (ZIF), a type of metal-organic framework (MOF). The novel synthetic chemistry enables accurate size control of Fe-doped ZIF catalyst particles with a wide range from 20 to 1000 nm without changing chemical properties, which provides a great opportunity to increase the density of active sites that is determined by the particle size. We elucidated the active site formation mechanism by correlating the chemical and structural changes with thermal activation process for the conversion from Fe-N4 complex containing hydrocarbon networks in ZIF to highly active FeNx sites embedded into carbon. A temperature of 800oC was identified as the critical point to start forming pyridinic nitrogen doping at the edge of the graphitized carbon planes. Further increasing heating temperature to 1100oC leads to increase of graphitic nitrogen, generating possible synergistic effect with FeNx sites to promote ORR activity. The best performing catalyst, which has well-defined particle size around 50 nm and abundance of atomic FeNx sites embedded into carbon structures, achieve a new performance milestone for the ORR in acid including a half-wave potential of 0.85 V vs RHE and only 20 mV loss after 10,000 cycles in O2 saturated H2SO4 electrolyte. The new class PGM-free catalyst with approaching activity to Pt holds great promise for future PEM fuel cells.

  20. Polypyrrole-palladium nanocomposite coating of micrometer-sized polymer particles toward a recyclable catalyst.

    Science.gov (United States)

    Fujii, Syuji; Matsuzawa, Soichiro; Hamasaki, Hiroyuki; Nakamura, Yoshinobu; Bouleghlimat, Azzedine; Buurma, Niklaas J

    2012-02-07

    coated with PPy-Pd nanocomposite, and stable aqueous dispersions were obtained. The nanocomposite particles functioned as an efficient catalyst for the aerobic oxidative homocoupling reaction of 4-carboxyphenylboronic acid in aqueous media for the formation of carbon-carbon bonds. The composite particles sediment in a short time (catalyst is easy.

  1. Transient Effects in Fischer-Tropsch Reactor with a Fixed Bed of Catalyst Particles

    Directory of Open Access Journals (Sweden)

    I. V. Derevich

    2015-01-01

    Full Text Available Based on analysis of small temperature disturbances in the Fischer-Tropsch reactor with a fixed bed of catalyst particles various scenarios of thermal instability were investigated. There are two possible scenarios of thermal instability of the reactor. First, thermal explosion may occur due to growth of temperature disturbances inside a catalytic granule. Second scenario connected with loss of thermal stability as a result of an initial increase in temperature in the reactor volume. The boundaries of thermal stability of the reactor were estimated by solving the eigenvalue problems for spherical catalyst particles and cylindrical reactor. Processes of diffusional resistance inside the catalytic granule and heat transfer from wall of the reactor tube are taken into account. Estimation of thermal stability area is compared with the results of numerical simulation of behavior of temperature and concentration of synthesis gas.

  2. Single Atomic Iron Catalysts for Oxygen Reduction in Acidic Media: Particle Size Control and Thermal Activation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hanguang; Hwang, Sooyeon; Wang, Maoyu; Feng, Zhenxing; Karakalos, Stavros; Luo, Langli; Qiao, Zhi; Xie, Xiaohong; Wang, Chongmin; Su, Dong; Shao, Yuyan; Wu, Gang (BNL); (Oregon State U.); (SC); (PNNL); (Buffalo)

    2017-09-26

    It remains a grand challenge to replace platinum group metal (PGM) catalysts with earth-abundant materials for the oxygen reduction reaction (ORR) in acidic media, which is crucial for large-scale deployment of proton exchange membrane fuel cells (PEMFCs). Here, we report a high-performance atomic Fe catalyst derived from chemically Fe-doped zeolitic imidazolate frameworks (ZIFs) by directly bonding Fe ions to imidazolate ligands within 3D frameworks. Although the ZIF was identified as a promising precursor, the new synthetic chemistry enables the creation of well-dispersed atomic Fe sites embedded into porous carbon without the formation of aggregates. The size of catalyst particles is tunable through synthesizing Fe-doped ZIF nanocrystal precursors in a wide range from 20 to 1000 nm followed by one-step thermal activation. Similar to Pt nanoparticles, the unique size control without altering chemical properties afforded by this approach is able to increase the number of PGM-free active sites. The best ORR activity is measured with the catalyst at a size of 50 nm. Further size reduction to 20 nm leads to significant particle agglomeration, thus decreasing the activity. Using the homogeneous atomic Fe model catalysts, we elucidated the active site formation process through correlating measured ORR activity with the change of chemical bonds in precursors during thermal activation up to 1100 °C. The critical temperature to form active sites is 800 °C, which is associated with a new Fe species with a reduced oxidation number (from Fe3+ to Fe2+) likely bonded with pyridinic N (FeN4) embedded into the carbon planes. Further increasing the temperature leads to continuously enhanced activity, linked to the rise of graphitic N and Fe–N species. The new atomic Fe catalyst has achieved respectable ORR activity in challenging acidic media (0.5 M H2SO4), showing a half-wave potential of 0.85 V vs RHE and leaving only a 30 mV gap with Pt/C (60 μgPt/cm2). Enhanced stability

  3. Magnetic properties of iron catalyst particles in HiPco single wall carbon nanotubes

    Czech Academy of Sciences Publication Activity Database

    Bittová, Barbara; Poltierová Vejpravová, Jana; Kalbáč, Martin; Burianová, Simona; Mantlíková, A.; Daniš, S.; Doyle, S.

    2011-01-01

    Roč. 115, č. 35 (2011), s. 17303-17309 ISSN 1932-7447 R&D Projects: GA ČR GAP204/10/1677 Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z40400503 Keywords : metal catalyst particles * carbon nanotubes * superparamagnet * core - shell model * inter-particle interactions Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.805, year: 2011 http://pubs.acs.org/doi/abs/10.1021/jp203365g

  4. Separation of Fischer-Tropsch Wax Products from Ultrafine Iron Catalyst Particles

    Energy Technology Data Exchange (ETDEWEB)

    James K. Neathery; Gary Jacobs; Amitava Sarkar; Burtron H. Davis

    2006-03-31

    The morphological and chemical nature of ultrafine iron catalyst particles (3-5 nm diameters) during activation/FTS was studied by HRTEM, EELS, and Moessbauer spectroscopy. With the progress of FTS, the carbide re-oxidized to magnetite and catalyst activity gradually decreased. The growth of oxide phase continued and average particle size also increased simultaneously. The phase transformation occurred in a ''growing oxide core'' manner with different nano-zones. The nano-range carbide particles did not show fragmentation or attrition as generally observed in micrometer range particles. Nevertheless, when the dimension of particles reached the micrometer range, the crystalline carbide phase appeared to be sprouted on the surface of magnetite single crystal. In the previous reporting period, a design and operating philosophy was developed for an integrated wax filtration system for a 4 liter slurry bubble column reactor to be used in Phase II of this research program. During the current reporting period, we have started construction of the new filtration system and began modifications to the 4 liter slurry bubble column reactor (SBCR) reactor. The system will utilize a primary wax separation device followed by a Pall Accusep or Membralox ceramic cross-flow membrane. As of this writing, the unit is nearly complete except for the modification of a moyno-type pump; the pump was shipped to the manufacturer to install a special leak-free, high pressure seal.

  5. Bimetallic Ag–Ni/C particles as cathode catalyst in AFCs (alkaline fuel cells)

    International Nuclear Information System (INIS)

    Song, Xingjuan; Zhang, Dongming

    2014-01-01

    AFCs (alkaline fuel cells) is one of the promising fuel cells, due to their low working temperature and less corrosive environment. However, decreasing the catalyst cost and improving its performance are still the challenges in its application. Transition metal as the catalyst for AFCs not only can reduce its cost, but also has great electro-catalytic efficiency. In this paper, Carbon supported Ag–Ni bimetallic catalysts with differential Ag/Ni atomic ratios were prepared by chemically reducing silver and nickel salts. Ag 3 Ni/C shows the relatively higher ORR (oxygen reduction reaction) activity among the differential Ag/Ni bimetallic particles. In order to improve the activity and stability, the catalysts were heat-treated at the temperature of 500 °C. The results indicate that the limiting current density has been improved greatly for Ag 3 Ni/C-500 °C, which is as high as 2.5× that of Ag/C. The microstructure investigation show that the non-equilibrium state of Ag–Ni alloy by heat treatment is confirmed by HRTEM (high-resolution transmission electron microscopy) images, and Ag(111) surfaces are decreased in XRD pattern, which results in the ORR activity improved and overpotential decreased. Heat treatment also has contributed to Ag–Ni/C electrochemistry stability in some degree. - Highlights: • Ag–Ni/C is applied as cathode catalyst for AFCs (alkaline fuel cells). • Ag 3 Ni/C-500 °C shows the best performance. • Non-equilibrium state of Ag–Ni alloy by heat treatment is observed. • The decreased Ag(111) surfaces are favor to improve the catalyst activity

  6. Sustainable utilization of waste palm oil and sulfonated carbon catalyst derived from coconut meal residue for biodiesel production.

    Science.gov (United States)

    Thushari, Indika; Babel, Sandhya

    2018-01-01

    In this study, an inexpensive, environmental benign acid catalyst is prepared using coconut meal residue (CMR) and employed for biodiesel production from waste palm oil (WPO). The total acid density of the catalyst is found to be 3.8mmolg -1 . The catalyst shows a unique amorphous structure with 1.33m 2 g -1 of surface area and 0.31cm 3 g -1 of mean pore volume. Successful activation is confirmed by Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The highest biodiesel yield of 92.7% was obtained from WPO in an open reflux system using the catalyst. Results show that biodiesel yield increases with increasing methanol:oil (molar ratio) and reaction time up to an optimum value. It is found that the catalyst can be reused for at least four cycles for >80% biodiesel yield. Fuel properties of the produced biodiesel meet international biodiesel standards. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Nickel Particles Selectively Confined in the Mesoporous Channels of SBA-15 Yielding a Very Stable Catalyst for DRM Reaction.

    Science.gov (United States)

    Rodriguez-Gomez, Alberto; Pereñiguez, Rosa; Caballero, Alfonso

    2018-01-18

    A series of four Ni catalysts supported on SBA-15 and on a high SiO 2 surface area have been prepared by modified impregnation (ImU) and deposition-precipitation (DP) methods. The catalysts have been extensively characterized, including in situ XAS (bulk sensitive) and XPS (surface sensitive) techniques, and their catalytic activities evaluated in the dry reforming reaction of methane (DRM). The combined use of XPS and XAS has allowed us to determine the location of nickel particles on each catalyst after reduction at high temperature (750 °C). Both Ni/SiO 2 -DP and Ni/SBA-15-DP catalysts yield well-dispersed and homogeneous metallic phases mainly located in the mesoporosity of both supports. On the contrary, the Ni/SiO 2 -ImU and Ni/SBA-15-ImU catalysts present a bimodal distribution of the reduced nickel phase, with nickel metallic particles located out and into the mesoporous structure of SiO 2 or the SBA-15 channels. The Ni/SBA-15-DP catalyst was found the most stable and performing system, with a very low level of carbon deposition, about an order of magnitude lower than the equivalent ImU catalyst. This outstanding performance comes from the confinement of small and homogeneous nickel particles in the mesoporous channels of SBA-15, which, in strong interaction with the support, are resistant to sintering and coke deposition during the demanding reaction conditions of DRM.

  8. Application of nickel nanoparticles as catalyst in the viscosity reduction of Venezuelan atmospheric residues by water reformation

    Energy Technology Data Exchange (ETDEWEB)

    Golindano, T.; Martinez, S.; Pimentel, M.; Segovia, X.; Pena, J.P.; Sanchez, R.; Sardella, R. [PDVSA Petroleos de Venezuela SA, Caracas (Venezuela, Bolivarian Republic of). INTEVEP Dept. of Residue and Heavy Crude Processing; Canizales, E. [PDVSA Petroleos de Venezuela SA, Caracas (Venezuela, Bolivarian Republic of). INTEVEP Dept. of Analytics

    2009-07-01

    A catalytic upgrading process for extra-heavy crude oil was presented. Nickel nanoparticles were combined with transition metals and used as a catalyst for a water reformation process used to reduce oil viscosity. Thermal and catalytic process experiments were conducted in order to determine the catalytic activity of the nanoparticles. The nanoparticles were dispersed in gasoil in order to promote better interactions between the heavy feeds and the catalyst. The nanoparticles were characterized using transmission electron microscopy (TEM) and chemical analyses. The study showed that the nanoparticles increased the conversion rate from 14.6 p/p to 37.4 p/p. Bottom products generated by the catalytic process were of higher quality than products produced using thermal processing techniques. It was concluded that the nanostructured materials diminished the viscosity of the atmospheric residue. 5 refs., 6 tabs., 3 figs.

  9. Determination of platinum group metal catalyst residues in active pharmaceutical ingredients by means of total reflection X-ray spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Marguí, Eva, E-mail: eva.margui@udg.edu [Department of Chemistry, University of Girona, Campus Montilivi, 17071 Girona (Spain); Queralt, Ignasi, E-mail: iqueralt@ictja.csic.es [Laboratory of X-ray Analytical Applications, Institute of Earth Sciences “Jaume Almera”, CSIC, Solé Sabarís s/n, 08028 Barcelona (Spain); Hidalgo, Manuela, E-mail: manuela.hidalgo@udg.edu [Department of Chemistry, University of Girona, Campus Montilivi, 17071 Girona (Spain)

    2013-08-01

    The control of metal catalyst residues (i.e., platinum group metals (PGMs)) in different stages of the manufacturing processes of the active pharmaceutical ingredients (APIs) and, especially, in the final product is crucial. For API specimens, there are strict guidelines to limit the levels of metal residues based on their individual levels of safety concern. For PGMs the concentration limit has been established at 10 mg/kg in the API. Therefore great effort is currently being devoted to the development of new and simple procedures to control metals in pharmaceuticals. In the present work, an analytical methodology based on benchtop total reflection X-ray fluorescence spectrometry (TXRF) has been developed for the rapid and simple determination of some PGM catalyst impurities (Rh, Pd, Ir and Pt) in different types of API samples. An evaluation of different sample treatments (dissolution and digestion of the solid pharmaceutical samples) has been carried out and the developed methodologies have been validated according to the analytical parameters to be considered and acceptance criteria for PGM determination according to the United States Pharmacopeia (USP). Limits of quantification obtained for PGM metals were in the range of 2–4 mg/kg which are satisfactory according to current legislation. From the obtained results it is shown that the developed TXRF method can be implemented in the pharmaceutical industries to increase productivity of the laboratory; offering an interesting and complementary analytical tool to other atomic spectroscopic methods. - Highlights: • A TXRF method for PGM catalyst residue determination in API samples is presented. • Analysis can be performed using 10 μL of the internal standardized dissolved API. • The method is rapid, simple and suitable according to the USP requirements.

  10. Chitosan-coated Silica Nanoparticles - A Potential Support for Metal Particles used as Heterogeneous Catalyst

    International Nuclear Information System (INIS)

    Haghighizadeh, A.; Abu Bakar, M.; Ghani, S.A.; Abu Bakar, N.H.H.

    2011-01-01

    In this work a strategy to immobilize noble metal nanoparticles on silica microspheres is proposed. In order to achieve this, monodispersed silica nanoparticles of an average size of 63.5±6.7 nm were synthesized via sol-gel method. Then chitosan was coated onto the silica to create a core/ shell composite with the size range of 66.56±9.78 nm to 79.18±11.87 nm. The noble metal nanoparticles were then synthesized on the shell of the composite through coordination of the respective metal ions to the polymer followed by the subsequent reduction. In this way, the silver particles of average size 6.17±1.83 nm, 9.85±2.60 nm, and 11.80±4.26 nm have been synthesized on the shell successfully. The optimized supported metal particles can be used as a potential heterogeneous catalyst. (author)

  11. Effects of the application of different particle sizes of mill scale (residue) in mass red ceramic

    International Nuclear Information System (INIS)

    Arnt, A.B.C.; Rocha, M.R.; Meller, J.G.

    2012-01-01

    This study aims to evaluate the influence of particle size of mill scale, residue, when added to a mass ceramic. This residue rich in iron oxide may be used as pigment in the ceramics industry. The use of pigments in ceramic products is related to the characteristics of non-toxicity, chemical stability and determination of tone. The tendency to solubilize the pigment depends on the specific surface area. The residue study was initially subjected to physical and chemical characterization and added in a proportion of 5% at a commercial ceramic white burning, with different particle sizes. Both formulations were sintered at a temperature of 950 ° C and evaluated for: loss on ignition, firing linear shrinkage, water absorption, flexural strength and difference of tone. Samples with finer particles of mill scale 0.038 μ showed higher mechanical strength values in the order of 18 MPa. (author)

  12. Removal of residual palm oil-based biodiesel catalyst using membrane ultra-filtration technique: An optimization study

    Directory of Open Access Journals (Sweden)

    I.M. Atadashi

    2014-09-01

    Full Text Available In this research work, residual potassium hydroxide catalyst was removed from palm oil-based alkyl esters (biodiesel using membrane separative technique, with the aim of achieving high-quality biodiesel that meets international standard specifications. Further, Central Composite Design (CCD coupled with Response Surface Methodology (RSM was employed to study the effects of the system variables such as flow rate, temperature and transmembrane pressure (TMP on the retention of potassium. At the optimum conditions, the coefficient of retention (%R of the catalyst was 93.642, and the content of the potassium was reduced from 8.328 mg/L to 0.312 mg/L; a value well below the one specified by both EN 14214 and ASTM D6751 standards. In addition, the comparison between predicted and experimental values for the catalyst retention offers a reasonable percentage error of 0.081%. Therefore, this study has proven that membrane technique can be used to post treat crude biodiesel; in order to achieve high-quality biodiesel fuel that can be efficiently used on diesel engines.

  13. Correlating particle size and shape of supported Ru/gamma-Al2O3 catalysts with NH3 decomposition activity.

    Science.gov (United States)

    Karim, Ayman M; Prasad, Vinay; Mpourmpakis, Giannis; Lonergan, William W; Frenkel, Anatoly I; Chen, Jingguang G; Vlachos, Dionisios G

    2009-09-02

    While ammonia synthesis and decomposition on Ru are known to be structure-sensitive reactions, the effect of particle shape on controlling the particle size giving maximum turnover frequency (TOF) is not understood. By controlling the catalyst pretreatment conditions, we have varied the particle size and shape of supported Ru/gamma-Al(2)O(3) catalysts. The Ru particle shape was reconstructed by combining microscopy, chemisorption, and extended X-ray absorption fine structure (EXAFS) techniques. We show that the particle shape can change from a round one, for smaller particles, to an elongated, flat one, for larger particles, with suitable pretreatment. Density functional theory calculations suggest that the calcination most likely leads to planar structures. We show for the first time that the number of active (here B(5)) sites is highly dependent on particle shape and increases with particle size up to 7 nm for flat nanoparticles. The maximum TOF (based on total exposed Ru atoms) and number of active (B(5)) sites occur at approximately 7 nm for elongated nanoparticles compared to at approximately 1.8-3 nm for hemispherical nanoparticles. A complete, first-principles based microkinetic model is constructed that can quantitatively describe for the first time the effect of varying particle size and shape on Ru activity and provide further support of the characterization results. In very small nanoparticles, particle size polydispersity (due to the presence of larger particles) appears to be responsible for the observed activity.

  14. Determination of platinum group metal catalyst residues in active pharmaceutical ingredients by means of total reflection X-ray spectrometry

    Science.gov (United States)

    Marguí, Eva; Queralt, Ignasi; Hidalgo, Manuela

    2013-08-01

    The control of metal catalyst residues (i.e., platinum group metals (PGMs)) in different stages of the manufacturing processes of the active pharmaceutical ingredients (APIs) and, especially, in the final product is crucial. For API specimens, there are strict guidelines to limit the levels of metal residues based on their individual levels of safety concern. For PGMs the concentration limit has been established at 10 mg/kg in the API. Therefore great effort is currently being devoted to the development of new and simple procedures to control metals in pharmaceuticals. In the present work, an analytical methodology based on benchtop total reflection X-ray fluorescence spectrometry (TXRF) has been developed for the rapid and simple determination of some PGM catalyst impurities (Rh, Pd, Ir and Pt) in different types of API samples. An evaluation of different sample treatments (dissolution and digestion of the solid pharmaceutical samples) has been carried out and the developed methodologies have been validated according to the analytical parameters to be considered and acceptance criteria for PGM determination according to the United States Pharmacopeia (USP). Limits of quantification obtained for PGM metals were in the range of 2-4 mg/kg which are satisfactory according to current legislation. From the obtained results it is shown that the developed TXRF method can be implemented in the pharmaceutical industries to increase productivity of the laboratory; offering an interesting and complementary analytical tool to other atomic spectroscopic methods.

  15. Chemical imaging of single catalyst particles with scanning μ-XANES-CT and μ-XRF-CT.

    Science.gov (United States)

    Price, S W T; Ignatyev, K; Geraki, K; Basham, M; Filik, J; Vo, N T; Witte, P T; Beale, A M; Mosselmans, J F W

    2015-01-07

    The physicochemical state of a catalyst is a key factor in determining both activity and selectivity; however these materials are often not structurally or compositionally homogeneous. Here we report on the 3-dimensional imaging of an industrial catalyst, Mo-promoted colloidal Pt supported on carbon. The distribution of both the active Pt species and Mo promoter have been mapped over a single particle of catalyst using microfocus X-ray fluorescence computed tomography. X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure revealed a mixed local coordination environment, including the presence of both metallic Pt clusters and Pt chloride species, but also no direct interaction between the catalyst and Mo promoter. We also report on the benefits of scanning μ-XANES computed tomography for chemical imaging, allowing for 2- and 3-dimensional mapping of the local electronic and geometric environment, in this instance for both the Pt catalyst and Mo promoter throughout the catalyst particle.

  16. Comparison of mineral dust and droplet residuals measured with two single particle aerosol mass spectrometers

    Science.gov (United States)

    Wonaschütz, Anna; Ludwig, Wolfgang; Zawadowicz, Maria; Hiranuma, Naruki; Hitzenberger, Regina; Cziczo, Daniel; DeMott, Paul; Möhler, Ottmar

    2017-04-01

    Single Particle mass spectrometers are used to gain information on the chemical composition of individual aerosol particles, aerosol mixing state, and other valuable aerosol characteristics. During the Mass Spectrometry Intercomparison at the Fifth Ice Nucleation (FIN-01) Workshop, the new LAAPTOF single particle aerosol mass spectrometer (AeroMegt GmbH) was conducting simultaneous measurements together with the PALMS (Particle Analysis by Laser Mass Spectrometry) instrument. The aerosol particles were sampled from the AIDA chamber during ice cloud expansion experiments. Samples of mineral dust and ice droplet residuals were measured simultaneously. In this work, three expansion experiments are chosen for a comparison between the two mass spectrometers. A fuzzy clustering routine is used to group the spectra. Cluster centers describing the ensemble of particles are compared. First results show that while differences in the peak heights are likely due to the use of an amplifier in PALMS, cluster centers are comparable.

  17. Single particle measurements of the chemical composition of cirrus ice residue during CRYSTAL-FACE

    Science.gov (United States)

    Cziczo, D. J.; Murphy, D. M.; Hudson, P. K.; Thomson, D. S.

    2004-02-01

    The first real-time, in situ, investigation of the chemical composition of the residue of cirrus ice crystals was performed during July 2002. This study was undertaken on a NASA WB-57F high-altitude research aircraft as part of CRYSTAL-FACE, a field campaign which sought to further our understanding of the relation of clouds, water vapor, and climate by characterizing, among other parameters, anvil cirrus formed about the Florida peninsula. A counter flow virtual impactor (CVI) was used to separate cirrus ice from the unactivated interstitial aerosol particles and evaporate condensed-phase water. Residual material, on a crystal-by-crystal basis, was subsequently analyzed using the NOAA Aeronomy Laboratory's Particle Analysis by Laser Mass Spectrometry (PALMS) instrument. Sampling was performed from 5 to 15 km altitude and from 12° to 28° north latitude within cirrus originating over land and ocean. Chemical composition measurements provided several important results. Sea salt was often incorporated into cirrus, consistent with homogeneous ice formation by aerosol particles from the marine boundary layer. Size measurements showed that large particles preferentially froze over smaller ones. Meteoritic material was found within ice crystals, indicative of a relation between stratospheric aerosol particles and tropospheric clouds. Mineral dust was the dominant residue observed in clouds formed during a dust transport event from the Sahara, consistent with a heterogeneous freezing mechanism. These results show that chemical composition and size are important determinants of which aerosol particles form cirrus ice crystals.

  18. Online single particle analysis of ice particle residuals from mountain-top mixed-phase clouds using laboratory derived particle type assignment

    Science.gov (United States)

    Schmidt, Susan; Schneider, Johannes; Klimach, Thomas; Mertes, Stephan; Schenk, Ludwig Paul; Kupiszewski, Piotr; Curtius, Joachim; Borrmann, Stephan

    2017-01-01

    In situ single particle analysis of ice particle residuals (IPRs) and out-of-cloud aerosol particles was conducted by means of laser ablation mass spectrometry during the intensive INUIT-JFJ/CLACE campaign at the high alpine research station Jungfraujoch (3580 m a.s.l.) in January-February 2013. During the 4-week campaign more than 70 000 out-of-cloud aerosol particles and 595 IPRs were analyzed covering a particle size diameter range from 100 nm to 3 µm. The IPRs were sampled during 273 h while the station was covered by mixed-phase clouds at ambient temperatures between -27 and -6 °C. The identification of particle types is based on laboratory studies of different types of biological, mineral and anthropogenic aerosol particles. The outcome of these laboratory studies was characteristic marker peaks for each investigated particle type. These marker peaks were applied to the field data. In the sampled IPRs we identified a larger number fraction of primary aerosol particles, like soil dust (13 ± 5 %) and minerals (11 ± 5 %), in comparison to out-of-cloud aerosol particles (2.4 ± 0.4 and 0.4 ± 0.1 %, respectively). Additionally, anthropogenic aerosol particles, such as particles from industrial emissions and lead-containing particles, were found to be more abundant in the IPRs than in the out-of-cloud aerosol. In the out-of-cloud aerosol we identified a large fraction of aged particles (31 ± 5 %), including organic material and secondary inorganics, whereas this particle type was much less abundant (2.7 ± 1.3 %) in the IPRs. In a selected subset of the data where a direct comparison between out-of-cloud aerosol particles and IPRs in air masses with similar origin was possible, a pronounced enhancement of biological particles was found in the IPRs.

  19. Particle Size and Crystal Phase Effects in Fischer-Tropsch Catalysts

    Directory of Open Access Journals (Sweden)

    Jin-Xun Liu

    2017-08-01

    Full Text Available Fischer-Tropsch synthesis (FTS is an increasingly important approach for producing liquid fuels and chemicals via syngas—that is, synthesis gas, a mixture of carbon monoxide and hydrogen—generated from coal, natural gas, or biomass. In FTS, dispersed transition metal nanoparticles are used to catalyze the reactions underlying the formation of carbon-carbon bonds. Catalytic activity and selectivity are strongly correlated with the electronic and geometric structure of the nanoparticles, which depend on the particle size, morphology, and crystallographic phase of the nanoparticles. In this article, we review recent works dealing with the aspects of bulk and surface sensitivity of the FTS reaction. Understanding the different catalytic behavior in more detail as a function of these parameters may guide the design of more active, selective, and stable FTS catalysts.

  20. Catalyst deactivation due to deposition of reaction products in macropores during hydroprocessing of petroleum residuals

    Energy Technology Data Exchange (ETDEWEB)

    Khang, S.J.; Mosby, J.F.

    1986-04-01

    A pore-filling model is proposed to describe deactivation of hydroprocessing catalysts of a wide-pore structure in well-mixed and plug-flow reactors where the catalyst pellets are deactivated due to slow and uniform deposition of reaction products (mostly metal compounds) in their macropores. The model based on no mass-transfer restriction in the main channels of the pores incorporates additional active sites created by metal compounds in the deposited layers and has been shown to have two parameters of the similar type of the Thiele modulus. The model along with lumped reaction kinetics is applied for hydroprocessing reactions in trickle-bed reactors and provides reasonable deactivation curves for desulfurization and demetallation reaction when less than 50% of the original pore volume is filled with metal compounds.

  1. Effect of Silica Particle Size on Texture, Structure, and Catalytic Performance of Cu/SiO2 Catalysts for Glycerol Hydrogenolysis

    Science.gov (United States)

    Qi, Ye Tong; Zhe, Chen Hong; Ning, Xiang

    2018-03-01

    The influences of carrier particle sizes of Cu/SiO2 catalysts for hydrogenolysis of glycerol were studied use mono-dispersed silica as models. Catalysts were prepared by precipitation method with the average size of the mono-dispersed silica supports varying of 10, 20, and 90 nm. Characterization of the catalysts show that the physical properties such as pore volume and BET surface area of the catalysts were largely affected by the carrier particle size of silica. However, the copper dispersion of the three samples were similar. XPS patterns show a difference in the chemical states of copper species, small carrier particle size induced formation of copper phyllosilicate, which benefits on the stability of copper species in reaction. The overall activity in the reaction of glycerol hydrogenolysis shows a correlation with the carrier particle size. The small carrier particles prevent the copper species from aggregation thus such catalysts exhibit good catalytic activity and stability.

  2. Gunshot residue particles formed by using ammunitions that have mercury fulminate based primers.

    Science.gov (United States)

    Zeichner, A; Levin, N; Dvorachek, M

    1992-11-01

    Ammunition having mercury fulminate-based primers are commonly manufactured by Eastern Bloc countries and used extensively in the Middle East. Gunshot residue (GSR) particles formed by firing these types of ammunition were examined. It was observed that much lower percentage of mercury-containing GSR particles were found in samples taken from a shooter as compared to the percentage of such particles in samples from cartridge cases. This fact must therefore be taken into account when interpreting case results. A plausible explanation for the results described is proposed.

  3. Pilot‐scale investigation and CFD modeling of particle deposition in low‐dust monolithic SCR DeNOx catalysts

    DEFF Research Database (Denmark)

    Heiredal, Michael Lykke; Jensen, Anker Degn; Thøgersen, Joakim Reimer

    2013-01-01

    Deposition of particles in selective catalytic reduction DeNOx monolithic catalysts was studied by low‐dust pilot‐scale experiments. The experiments showed a total deposition efficiency of about 30%, and the deposition pattern was similar to that observed in full‐scale low‐dust applications. On e...

  4. Selective Hydrogenation of Acrolein Over Pd Model Catalysts: Temperature and Particle-Size Effects.

    Science.gov (United States)

    O'Brien, Casey P; Dostert, Karl-Heinz; Schauermann, Swetlana; Freund, Hans-Joachim

    2016-10-24

    The selectivity in the hydrogenation of acrolein over Fe 3 O 4 -supported Pd nanoparticles has been investigated as a function of nanoparticle size in the 220-270 K temperature range. While Pd(111) shows nearly 100 % selectivity towards the desired hydrogenation of the C=O bond to produce propenol, Pd nanoparticles were found to be much less selective towards this product. In situ detection of surface species by using IR-reflection absorption spectroscopy shows that the selectivity towards propenol critically depends on the formation of an oxopropyl spectator species. While an overlayer of oxopropyl species is effectively formed on Pd(111) turning the surface highly selective for propenol formation, this process is strongly hindered on Pd nanoparticles by acrolein decomposition resulting in CO formation. We show that the extent of acrolein decomposition can be tuned by varying the particle size and the reaction temperature. As a result, significant production of propenol is observed over 12 nm Pd nanoparticles at 250 K, while smaller (4 and 7 nm) nanoparticles did not produce propenol at any of the temperatures investigated. The possible origin of particle-size dependence of propenol formation is discussed. This work demonstrates that the selectivity in the hydrogenation of acrolein is controlled by the relative rates of acrolein partial hydrogenation to oxopropyl surface species and of acrolein decomposition, which has significant implications for rational catalyst design. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Effectiveness of non-noble metal based diesel oxidation catalysts on particle number emissions from diesel and biodiesel exhaust.

    Science.gov (United States)

    Shukla, Pravesh Chandra; Gupta, Tarun; Labhasetwar, Nitin Kumar; Khobaragade, Rohini; Gupta, Neeraj K; Agarwal, Avinash Kumar

    2017-01-01

    Two new formulations of non-noble metal based diesel oxidation catalysts based on CoCe based mixed oxide (DOC 2 ) and perovskite catalysts (DOC 3 ) were prepared and retrofitted in a 4-cylinder diesel engine fueled by diesel and Karanja biodiesel blend (KB20). In this study, their effectiveness in reducing raw exhaust particulate emissions vis-à-vis a commercial diesel oxidation catalyst (DOC 1 ) was evaluated. Emission characteristics such as particle number-size distribution, mass-size distribution, and surface area-size distribution, total particle number concentration and count mean diameter as a function of engine load at constant engine speed were evaluated. Variations in total particle number concentration as a function of engine speed were also determined. The prepared DOCs and the commercial DOC showed varying degrees of performance as a function of engine operating conditions. Overall, effectiveness of the prepared DOC's appeared to be more fuel specific. For diesel exhaust, overall performance of DOC 1 was more effective compared to both prepared DOCs, with DOC 2 being superior to DOC 3 . In case of KB20 exhaust, the overall performance of DOC 2 was either more effective or nearly comparable to DOC 1, while DOC 3 being not so effective. This showed that the DOCs based on CoCe based mixed oxide catalysts have potential to replace commercial noble metal based DOC's, especially in engines fueled by biodiesel. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Matrix Characterization of Plutonium Residues by Alpha-Particle Self-Interrogation

    International Nuclear Information System (INIS)

    Prettyman, T.H.; Foster, L.A.; Staples, P.

    1998-01-01

    Legacy plutonium residues often have inadequate item descriptions. Nondestructive characterization can help segregate these items for reprocessing or provide information needed for disposal or storage. Alpha particle-induced gamma-ray spectra contain a wealth of information that can be used for matrix characterization. We demonstrate how this information can be used for item identification. Gamma-ray spectra were recorded at the Los Alamos Plutonium Facility from a variety of legacy, plutonium-processing residues and product materials. The comparison and analysis of these spectra are presented

  7. In situ chemical composition measurement of individual cloud residue particles at a mountain site, southern China

    Directory of Open Access Journals (Sweden)

    Q. Lin

    2017-07-01

    Full Text Available To investigate how atmospheric aerosol particles interact with chemical composition of cloud droplets, a ground-based counterflow virtual impactor (GCVI coupled with a real-time single-particle aerosol mass spectrometer (SPAMS was used to assess the chemical composition and mixing state of individual cloud residue particles in the Nanling Mountains (1690 m a. s. l. , southern China, in January 2016. The cloud residues were classified into nine particle types: aged elemental carbon (EC, potassium-rich (K-rich, amine, dust, Pb, Fe, organic carbon (OC, sodium-rich (Na-rich and Other. The largest fraction of the total cloud residues was the aged EC type (49.3 %, followed by the K-rich type (33.9 %. Abundant aged EC cloud residues that mixed internally with inorganic salts were found in air masses from northerly polluted areas. The number fraction (NF of the K-rich cloud residues increased within southwesterly air masses from fire activities in Southeast Asia. When air masses changed from northerly polluted areas to southwesterly ocean and livestock areas, the amine particles increased from 0.2 to 15.1 % of the total cloud residues. The dust, Fe, Pb, Na-rich and OC particle types had a low contribution (0.5–4.1 % to the total cloud residues. Higher fraction of nitrate (88–89 % was found in the dust and Na-rich cloud residues relative to sulfate (41–42 % and ammonium (15–23 %. Higher intensity of nitrate was found in the cloud residues relative to the ambient particles. Compared with nonactivated particles, nitrate intensity decreased in all cloud residues except for dust type. To our knowledge, this study is the first report on in situ observation of the chemical composition and mixing state of individual cloud residue particles in China.

  8. In-situ observations of interstitial aerosol particles and cloud residues found in contrails

    Energy Technology Data Exchange (ETDEWEB)

    Stroem, J. [Stockholm Univ. (Sweden). Dept. of Meteorology

    1997-12-31

    In spring 1994 a series of flights were conducted in cirrus clouds and contrails over southern Germany. One of the aims of this campaign was to study the phase partitioning of aerosols and water in these clouds. To achieve this separation of particles two complementary sampling probes were mounted on the research aircraft Falcon. These are the Counterflow Virtual Impactor (CVI) or super-micrometer inlet, and the interstitial inlet or submicrometer inlet. The CVI is a device that inertially separates cloud elements larger than a certain aerodynamic size from the surrounding atmosphere into a warm, dry and particle free air. Assuming that each cloud element leaves behind only one residue particle, these measurements yield an equivalent number concentration for cloud particles having an aerodynamic diameter larger than the lower cut size of the CVI. The size distribution of the sampled aerosol and residual particles between 0.1 to 3.5 {mu}m diameter was measured by a PMS PCASP (Passive Cavity Aerosol Spectrometer) working alternatively on both inlets. The gas-phase water vapor content was measured by a cryogenic frost point mirror. (R.P.) 4 refs.

  9. Influence of residual catalyst on the properties of conjugated polyphenylenevinylene materials: Palladium nanoparticles and poor electrical performance

    DEFF Research Database (Denmark)

    Krebs, Frederik C; Nyberg, R.B.; Jørgensen, M.

    2004-01-01

    The synthesis of conjugated polymer materials using palladium catalysis was shown to result in a contamination of the polymer product with palladium nanoparticles that were difficult to detect and remove. The particle size was on the order of 20 nm, as evidenced by transmission electron microscopy...... (TEM). Further, electron spectroscopy for chemical analysis (ESCA), powder X-ray diffraction, and scanning electron microscopy (SEM) were employed to establish the chemical and physical nature of the catalyst remnants. We demonstrate the identity of many physical and chemical properties of the same...... polymer material prepared by two different routes: the palladium route and the condensation route. The performance in a device application of the two polymer materials was, however, very different, and the palladium route was demonstrated to give poor films with low breakdown voltages and short circuits....

  10. Particle size distribution and morphological changes in activated carbon-metal oxide hybrid catalysts prepared under different heating conditions.

    Science.gov (United States)

    Barroso-Bogeat, A; Alexandre-Franco, M; Fernández-González, C; Gómez-Serrano, V

    2016-03-01

    In catalysis processes, activated carbon (AC) and metal oxides (MOs) are widely used either as catalysts or as catalyst supports because of their unique properties. A combination of AC and a MO in a single hybrid material entails changes not only in the composition, microstructure and texture but also in the morphology, which may largely influence the catalytic behaviour of the resulting product. This work is aimed at investigating the modifications in the morphology and particle size distribution (PSD) for AC-MO hybrid catalysts as a result of their preparation under markedly different heating conditions. From a commercial AC and six MO (Al2O3, Fe2O3, ZnO, SnO2, TiO2 and WO3) precursors, two series of such catalysts are prepared by wet impregnation, oven-drying at 120 ºC, and subsequent heat treatment at 200 ºC or 850 ºC in inert atmosphere. The resulting samples are characterized in terms of their morphology and PSD by scanning electron microscopy and ImageJ processing program. Obtained results indicate that the morphology, PSD and degree of dispersion of the supported catalysts are strongly dependent both on the MO precursor and the heat treatment temperature. With the temperature rise, trends are towards the improvement of crystallinity, the broadening of the PSD and the increase in the average particle size, thus suggesting the involvement of sintering mechanisms. Such effects are more pronounced for the Fe, Sn and W catalysts due to the reduction of the corresponding MOs by AC during the heat treatment at 850 ºC. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

  11. Chemical composition of ambient aerosol, ice residues and cloud droplet residues in mixed-phase clouds: single particle analysis during the Cloud and Aerosol Characterization Experiment (CLACE 6

    Directory of Open Access Journals (Sweden)

    M. Kamphus

    2010-08-01

    Full Text Available Two different single particle mass spectrometers were operated in parallel at the Swiss High Alpine Research Station Jungfraujoch (JFJ, 3580 m a.s.l. during the Cloud and Aerosol Characterization Experiment (CLACE 6 in February and March 2007. During mixed phase cloud events ice crystals from 5–20 μm were separated from larger ice aggregates, non-activated, interstitial aerosol particles and supercooled droplets using an Ice-Counterflow Virtual Impactor (Ice-CVI. During one cloud period supercooled droplets were additionally sampled and analyzed by changing the Ice-CVI setup. The small ice particles and droplets were evaporated by injection into dry air inside the Ice-CVI. The resulting ice and droplet residues (IR and DR were analyzed for size and composition by the two single particle mass spectrometers: a custom-built Single Particle Laser-Ablation Time-of-Flight Mass Spectrometer (SPLAT and a commercial Aerosol Time-of-Flight Mass Spectrometer (ATOFMS, TSI Model 3800. During CLACE 6 the SPLAT instrument characterized 355 individual IR that produced a mass spectrum for at least one polarity and the ATOFMS measured 152 IR. The mass spectra were binned in classes, based on the combination of dominating substances, such as mineral dust, sulfate, potassium and elemental carbon or organic material. The derived chemical information from the ice residues is compared to the JFJ ambient aerosol that was sampled while the measurement station was out of clouds (several thousand particles analyzed by SPLAT and ATOFMS and to the composition of the residues of supercooled cloud droplets (SPLAT: 162 cloud droplet residues analyzed, ATOFMS: 1094. The measurements showed that mineral dust was strongly enhanced in the ice particle residues. Close to all of the SPLAT spectra from ice residues did contain signatures from mineral compounds, albeit connected with varying amounts of soluble compounds. Similarly, close to all of the ATOFMS IR spectra show a

  12. Composites based on PET and red mud residues as catalyst for organic removal from water

    Energy Technology Data Exchange (ETDEWEB)

    Bento, Natálya I.; Santos, Patrícia S.C. [Science and Technology Institute, Federal University of Alfenas, Rodovia José Aurélio Vilela, 11999, BR 267, Km 533, CEP 37715-400 Poços de Caldas, MG (Brazil); Souza, Talita E. de; Oliveira, Luiz C.A. [Department of Chemistry, Federal University of Minas Gerais, UFMG, Av. Antônio Carlos, 6627, Pampulha, 31270-901 Belo Horizonte, MG (Brazil); Castro, Cínthia S., E-mail: cinthia.soares.castro@gmail.com [Science and Technology Institute, Federal University of Alfenas, Rodovia José Aurélio Vilela, 11999, BR 267, Km 533, CEP 37715-400 Poços de Caldas, MG (Brazil)

    2016-08-15

    Highlights: • Composite based on carbon/iron oxide from PET and red mud wastes for organic contaminants oxidation. • Composites are mainly composed of hematite and a carbon matrix from PET decomposition. • RM/PET-15 presents the highest methylene blue (MB) removal from water, by combined adsorption and oxidation processes. • The dye oxidation was confirmed by ESI-MS studies. • The RM/PET catalysts can be reused for at least four batch runs. - Abstract: In this study, we obtained a composite based on carbon/iron oxide from red mud and PET (poly(ethylene terephthalate)) wastes by mechanical mixture (10, 15 and 20 wt.% of PET powder/red mud) followed by a controlled thermal treatment at 400 °C under air. XRD analyses revealed that the α-Fe{sub 2}O{sub 3} is the main phase formed from red mud. TPR analyses showed that the iron oxide present in the composites undergoes reduction at lower temperature to form Fe{sup 2+} species present in Fe{sub 3}O{sub 4}, indicating that the iron oxide in the composite can exhibit greater reactivity in the catalytic processes compared to the original red mud. In fact, catalytic tests showed that the composites presented higher capacity to remove methylene blue dye (MB), presenting about 90% of removal after 24 h of reaction. The MB removal was also monitored by mass spectrometer with ionization via electrospray (ESI-MS), which demonstrated the occurrence of the oxidation process, showing the formation of MB oxidation products. The stability of the composites was confirmed after four reuse cycles. The results seem to indicate that PET carbon deposited over the iron oxide from red mud promotes adsorption of the contaminant allowing its contact with the iron atoms and their consequent reaction.

  13. Correction: Particle shape optimization by changing from an isotropic to an anisotropic nanostructure: preparation of highly active and stable supported Pt catalysts in microemulsions.

    Science.gov (United States)

    Parapat, Riny Y; Wijaya, Muliany; Schwarze, Michael; Selve, Sören; Willinger, Marc; Schomäcker, Reinhard

    2016-04-07

    Correction for 'Particle shape optimization by changing from an isotropic to an anisotropic nanostructure: preparation of highly active and stable supported Pt catalysts in microemulsions' by Riny Y. Parapat et al., Nanoscale, 2013, 5, 796-805.

  14. Polyurethane foams containing residues of petroleum industry catalysts as recoverable pH-sensitive sorbents for aqueous pesticides.

    Science.gov (United States)

    Almeida, Marys Lene B; Ayres, Eliane; Moura, Flávia Cristina C; Oréfice, Rodrigo L

    2018-03-15

    To investigate ways of mitigating the contamination of water with herbicides, which is a well-recognized global problem, we prepared natural resource-based polyurethane foams containing different amounts of petroleum industry catalyst residue (RC) and tested them as atrazine (ATZ, a common herbicide) sorbents in aqueous solutions. The above sorbents were characterized by infrared spectroscopy, electron microscopy, microtomography, thermogravimetric analysis, and X-ray diffraction. The adsorption/desorption of ATZ thereon was investigated as a function of foam composition, pH, initial ATZ concentration, and time. The obtained results showed that the porosity, pore size, and pore interconnectivity of the prepared sorbents were well suited for optimal ATZ removal. At pH 2, foams with high RC contents achieved higher ATZ removal efficiencies (e.g., 25%) than the pristine foam (12%). Conversely, ATZ removal was disfavored at high pH, which was attributed to restricted ATZ-sorbent interactions due to changes in the sorbent surface charge. The presence of other species (such as pectin, which is usually found in fruits) did not interfere with ATZ removal. ATZ desorption was most effective at high pH, enabling the regeneration and re-use of sorbents and thus reducing large-scale application costs. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Facile and Low-Cost Preparation of Nb/Al Oxide Catalyst with High Performance for the Conversion of Kiwifruit Waste Residue to Levulinic Acid

    Directory of Open Access Journals (Sweden)

    Rui Wang

    2015-09-01

    Full Text Available The kiwifruit industry is booming worldwide. As a result, a great deal of kiwifruit waste residue (KWR containing monosaccharides is produced and discarded. This material shows great potential for the production of platform chemicals. In this study, a series of Nb/Al oxide catalysts were synthesized via a facile and low-cost coprecipitation method, and their structures were characterized using: thermal gravimetric analysis (TGA, XRD, FESEM, TEM, X-ray photoelectron spectroscopy (XPS, NH3-TPD, N2 adsorption-desorption, and FTIR-Pyridine adsorption. Experimental results of sugar-to-levulinic acid (LA conversion revealed that the 20%Nb/Al oxide catalyst provided the highest catalytic performance and durability in terms of LA yield from fructose (74.2% at 463 K after 10 min and from glucose (47.5% at 473 K after 15 min. Notably, the 20% Nb/Al oxide catalyst with a 10% dosage is capable of converting kiwifruit waste residue to LA at 473 K after 10 min. In conclusion, the enhanced catalytic performance was obtained due to the high acidity, and large surface areaof Nb/Al oxide catalyst.

  16. Re-examination of the Pt Particle Size Effect on the Oxygen Reduction Reaction for Ultrathin Uniform Pt/C Catalyst Layers without Influence from Nafion

    International Nuclear Information System (INIS)

    Shinozaki, Kazuma; Morimoto, Yu; Pivovar, Bryan S.; Kocha, Shyam S.

    2016-01-01

    Highlights: • Pt particle size effect on ORR was re-evaluated for Pt/C catalysts. • Nafion-free activity of Pt/C catalysts was evaluated using thin-film RDE methods. • Ultrathin-uniform catalyst layers were employed to obtain accurate activity values. • Specific activity increased steeply from 2 to 10 nm and less steeply at over 10 nm. • Re-evaluated effect agrees with a particle model assuming terrace active sites. - Abstract: The platinum ‘particle size effect’ on the oxygen reduction reaction (ORR) has been re-evaluated using commercial Pt/C catalysts (2–10 nm Pt particle) and polycrystalline Pt (poly-Pt) in 0.1 M HClO 4 with a rotating disk electrode method. Nafion-free catalyst layers were employed to obtain specific activities (SA) that were not perturbed (suppressed) by sulfonate anion adsorption/blocking. By using ultrathin uniform catalyst layers, O 2 diffusion limitation was minimized as confirmed from the high SAs of our supported catalysts that were comparable to unsupported sputtered Pt having controlled sizes. The specific activity (SA) steeply increased for the particle sizes in the range ∼2–10 nm (0.8–1.8 mA/cm 2 Pt at 0.9 V vs. RHE) and plateaued over ∼10 nm to 2.7 mA/cm 2 Pt for bulk poly-Pt. On the basis of the activity trend for the range of particle sizes studied, it appears that the effect of carbon support on activity is negligible. The experimental results and the concomitant profile of SA vs. particle size was found to be in an agreement to a truncated octahedral particle model that assumes active terrace sites.

  17. Tuning the structure of platinum particles on ceria in situ for enhancing the catalytic performance of exhaust gas catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Gaenzler, Andreas M.; Casapu, Maria; Grunwaldt, Jan-Dierk [Institute for Chemical Technology and Polymer Chemistry (ITCP), Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Vernoux, Philippe; Loridant, Stephane; Cadete Santos Aires, Francisco J. [Institut de Recherches sur la Catalyse et l' Environnement de Lyon, UMR 5256, CNRS, Universite Claude Bernard Lyon 1, Universite de Lyon, Villeurbanne (France); Epicier, Thierry [Materiaux, Ingenierie et Science, UMR 5510, CNRS, INSA de Lyon, Universite de Lyon, Villeurbanne (France); Betz, Benjamin [Umicore AG and Co. KG, Hanau (Germany); Ernst-Berl Institut, Technische Universitaet Darmstadt (Germany); Hoyer, Ruediger [Umicore AG and Co. KG, Hanau (Germany)

    2017-10-09

    A dynamic structural behavior of Pt nanoparticles on the ceria surface under reducing/oxidizing conditions was found at moderate temperatures (<500 C) and exploited to enhance the catalytic activity of Pt/CeO{sub 2}-based exhaust gas catalysts. Redispersion of platinum in an oxidizing atmosphere already occurred at 400 C. A protocol with reducing pulses at 250-400 C was applied in a subsequent step for controlled Pt-particle formation. Operando X-ray absorption spectroscopy unraveled the different extent of reduction and sintering of Pt particles: The choice of the reductant allowed the tuning of the reduction degree/particle size and thus the catalytic activity (CO>H{sub 2}>C{sub 3}H{sub 6}). This dynamic nature of Pt on ceria at such low temperatures (250-500 C) was additionally confirmed by in situ environmental transmission electron microscopy. A general concept is proposed to adjust the noble metal dispersion (size, structure), for example, during operation of an exhaust gas catalyst. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Tuning the structure of platinum particles on ceria in situ for enhancing the catalytic performance of exhaust gas catalysts

    International Nuclear Information System (INIS)

    Gaenzler, Andreas M.; Casapu, Maria; Grunwaldt, Jan-Dierk; Vernoux, Philippe; Loridant, Stephane; Cadete Santos Aires, Francisco J.; Epicier, Thierry; Betz, Benjamin; Hoyer, Ruediger

    2017-01-01

    A dynamic structural behavior of Pt nanoparticles on the ceria surface under reducing/oxidizing conditions was found at moderate temperatures (<500 C) and exploited to enhance the catalytic activity of Pt/CeO 2 -based exhaust gas catalysts. Redispersion of platinum in an oxidizing atmosphere already occurred at 400 C. A protocol with reducing pulses at 250-400 C was applied in a subsequent step for controlled Pt-particle formation. Operando X-ray absorption spectroscopy unraveled the different extent of reduction and sintering of Pt particles: The choice of the reductant allowed the tuning of the reduction degree/particle size and thus the catalytic activity (CO>H 2 >C 3 H 6 ). This dynamic nature of Pt on ceria at such low temperatures (250-500 C) was additionally confirmed by in situ environmental transmission electron microscopy. A general concept is proposed to adjust the noble metal dispersion (size, structure), for example, during operation of an exhaust gas catalyst. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Single particle analysis of ice crystal residuals observed in orographic wave clouds over Scandinavia during INTACC experiment

    Directory of Open Access Journals (Sweden)

    A. C. Targino

    2006-01-01

    Full Text Available Individual ice crystal residual particles collected over Scandinavia during the INTACC (INTeraction of Aerosol and Cold Clouds experiment in October 1999 were analyzed by Scanning Electron Microscopy (SEM equipped with Energy-Dispersive X-ray Analysis (EDX. Samples were collected onboard the British Met Office Hercules C-130 aircraft using a Counterflow Virtual Impactor (CVI. This study is based on six samples collected in orographic clouds. The main aim of this study is to characterize cloud residual elemental composition in conditions affected by different airmasses. In total 609 particles larger than 0.1 μm diameter were analyzed and their elemental composition and morphology were determined. Thereafter a hierarchical cluster analysis was performed on the signal detected with SEM-EDX in order to identify the major particle classes and their abundance. A cluster containing mineral dust, represented by aluminosilicates, Fe-rich and Si-rich particles, was the dominating class of particles, accounting for about 57.5% of the particles analyzed, followed by low-Z particles, 23.3% (presumably organic material and sea salt (6.7%. Sulfur was detected often across all groups, indicating ageing and in-cloud processing of particles. A detailed inspection of samples individually unveiled a relationship between ice crystal residual composition and airmass origin. Cloud residual samples from clean airmasses (that is, trajectories confined to the Atlantic and Arctic Oceans and/or with source altitude in the free troposphere were dominated primarily by low-Z and sea salt particles, while continentally-influenced airmasses (with trajectories that originated or traveled over continental areas and with source altitude in the continental boundary layer contained mainly mineral dust residuals. Comparison of residual composition for similar cloud ambient temperatures around –27°C revealed that supercooled clouds are more likely to persist in conditions where

  20. Combined Particle Filter and Selective Catalytic Reduction Catalyst for Diesel Engines

    DEFF Research Database (Denmark)

    Hvam, Jeanette

    oxidation of the silicon carbide crystals, ideal for catalyst adhesive layer. The silicon carbide filter, produced with trace amounts of copper, still fulfills the requirements for macroporosity and accessible porosity in excess of 50%, and is thus superior for the purpose of combined diesel particulate...

  1. Synthesis of MoVTeNb Oxide Catalysts with Tunable Particle Dimensions

    DEFF Research Database (Denmark)

    Kolenko, Yury V.; Zhang, Wei; d'Alnoncourt, Raoul Naumann

    2011-01-01

    Reliable procedures for the controlled synthesis of phase-pure MoVTeNb mixed oxides with M1 structure (ICSD 55097) and tunable crystal dimensions were developed to study the structure sensitivity of the selective oxidation of propane to acrylic acid. A series of powdered M1 catalysts was successf...

  2. NOVEL PREPARATION AND MAGNETO CHEMICAL CHARACTERIZATION OF NANO-PARTICLE MIXED ALCOHOL CATALYSTS

    Energy Technology Data Exchange (ETDEWEB)

    Seetala V. Naidu; Upali Siriwardane

    2005-01-14

    We have developed effective nanoparticle incorporated heterogeneous F-T catalysts starting with the synthesis of Fe, Co, Cu nanoparticles using Fe(acac){sub 3}, Co(acac){sub 2}, and Cu(acac){sub 2} precursors and incorporating the nanoparticles into alumina sol-gel to yield higher alkanes production. SEM/EDX, XRD, BET, VSM and SQUID experimental techniques were used to characterize the catalysts, and GC/MS were used for catalytic product analysis. The nanoparticle oxide method gave the highest metal loading. In case of mixed metals it seems that Co or Cu interferes and reduces Fe metal loading. The XRD pattern for nanoparticle mixed metal oxides show alloy formation between cobalt and iron, and between copper and iron in sol-gel prepared alumina granules. The alloy formation is also supported by DTA and VMS data. The magnetization studies were used to estimate the catalyst activity in pre- and post-catalysts. A lower limit of {approx}40% for the reduction efficiency was obtained due to hydrogenation at 450 C for 4 hrs. About 85% of the catalyst has become inactive after 25 hrs of catalytic reaction, probably by forming carbides of Fe and Co. The low temperature (300 K to 4.2 K) SQUID magnetometer results indicate a superparamagnetic character of metal nanoparticles with a wide size distribution of < 20 nm nanoparticles. We have developed an efficient and economical procedure for analyzing the F-T products using low cost GC-TCD system with hydrogen as a carrier gas. Two GC columns DC 200/500 and Supelco Carboxen-1000 column were tested for the separation of higher alkanes and the non-condensable gases. The Co/Fe on alumina sol-gel catalyst showed the highest yield for methane among Fe, Co, Cu, Co/Fe, Cu/Co, Fe/Cu. The optimization of CO/H{sub 2} ratio indicated that 1:1 ratio gave more alkanes distribution in F-T process with Co/Fe (6% each) impregnated on alumina mesoporous catalyst.

  3. Corrosion rate of steel embedded in blended Portland and fluid catalytic cracking catalyst residue (FC3R cement mortars

    Directory of Open Access Journals (Sweden)

    Payá, J.

    2008-12-01

    Full Text Available This paper reports on a study of the corrosion levels in steel bars embedded in mortars made with a blend of Portland cement and (0-20% spent fluid catalytic cracking catalyst residue (FC3R, with a variable (0.3-0.7 water/binder (w/b ratio. The specimens were stored in the following conditions: relative humidity of 40, 80 or 100% and CO2 concentrations of 5 and 100%. The steel corrosion rate was measured with polarization resistance techniques. In the absence of aggressive agents, the steel was found to remain duly passivated in mortars with an FC3R content of up to 15% under all the conditions of relative humidity tested. The reinforcement corrosion level in mortars with a w/b ratio of 0.3 and 15% FC3R subjected to accelerated carbonation was similar to the level observed in the unblended Portland cement control mortar.En este trabajo se ha estudiado el nivel de corrosión de barras de acero embebidas en morteros de cemento Portland con relación agua/material cementante (a/mc variable (0,3-0,7, en los que parte del cemento (0-20% se sustituyó por catalizador de craqueo usado (FC3R. Las condiciones de conservación de las probetas elaboradas fueron las siguientes: distintas humedades relativas (40, 80 y 100% y dos concentraciones de CO2 (5 y 100%. La velocidad de corrosión de los aceros se midió mediante la técnica de resistencia de polarización. Se ha podido determinar que, bajo las distintas condiciones de humedad relativa y ausencia de agresivo, los aceros se mantuvieron correctamente pasivados en los morteros con contenidos de FC3R de hasta el 15%. El nivel de corrosión que presenta el refuerzo embebidos en morteros con sustitución de un 15% de cemento por FC3R y relación a/mc 0,3, al ser sometidos a un proceso de carbonatación acelerada, era muy similar al mostrado por el mortero patrón, sin FC3R.

  4. Study on the effects of temperature, time and policy of pre polymerization on particle morphology in propylene slurry polymerization with heterogeneous ziegler-Natta catalysts

    International Nuclear Information System (INIS)

    Pircheraghi, G.; Pourmahdian, S.; Vatankhah, M.

    2008-01-01

    The effects of temperature, time and the strategy of pre polymerization were studied on the morphology of polypropylene particles. Propylene polymerization was carried out in slurry phase using fourth generation of Ziegler-Natta Catalyst, cyclohexylmethyl dimethoxysilane as external electron donor, and triethyl aluminum as co-catalyst. Pre polymerizations were carried out based on two strategies: isothermal and non-isothermal conditions. Particle imaging using SEM, bulk density, and particle size distribution was used to analyse the particle morphology. It was found that the variation of initial condition together with the change in the mechanism of particle fracture has a dominant effect on particle morphology. Each combination between the temperature and reaction time causes to have a special effect on the product particle morphology. It has become clear that in isothermal pre polymerization, spherical particles with identical properties were produced. In low temperature experiments particles with porous surface were observed. At increasing temperature, however, the pores disappeared. Non-isothermal pre polymerization produced different morphological types. In all experiments core shell structures were observed that seemed to be related to the structure of catalysts

  5. Hot alpha-emitting particles in residue of mining and metallurgy

    International Nuclear Information System (INIS)

    Freyer, K.; Treutler, H.C.; Weiss, H.; Ghose, R.; Selchau-Hansen, K.; Enge, W.

    1998-01-01

    Industrial residues of ore processing and metallurgy partly contain significant amounts of natural radionuclides. Such fine-grained, contaminated materials e.g. are scrubber dust slurry in the Mansfeld region, known as Theisenschlamm, and tailings of the uranium ore processing. The environmental significance of these materials in particular is related to the high mobility of its fine grain fractions by air and on the water path. By autoradiography using solid state nuclear track detectors the homogeneity of the distribution of alpha-emitting radionuclides in the above mentioned materials has been investigated. It has been found that beside a homogeneous background distribution of the alpha activity single spots with significant higher activity concentration exist in form of hot particles. Its concentration in different contaminated materials has been determined. A surfactant treatment process has been applied to separate uranium tailings material in different grain size fractions. The fractions have been characterized chemically, radiometrically and with respect to the amount of alpha-active hot particles. (orig.) [de

  6. Improved Oxygen Reduction Activity and Durability of Dealloyed PtCox Catalysts for Proton Exchange Membrane Fuel Cells: Strain, Ligand, and Particle Size Effects

    Science.gov (United States)

    Jia, Qingying; Caldwell, Keegan; Strickland, Kara; Ziegelbauer, Joseph M.; Liu, Zhongyi; Yu, Zhiqiang; Ramaker, David E.; Mukerjee, Sanjeev

    2015-01-01

    The development of active and durable catalysts with reduced platinum content is essential for fuel cell commercialization. Herein we report that the dealloyed PtCo/HSC and PtCo3/HSC nanoparticle (NP) catalysts exhibit the same levels of enhancement in oxygen reduction activity (~4-fold) and durability over pure Pt/C NPs. Surprisingly, ex situ high-angle annular dark field scanning transmission electron microscopy (HAADF STEM) shows that the bulk morphologies of the two catalysts are distinctly different: D-PtCo/HSC catalyst is dominated by NPs with solid Pt shells surrounding a single ordered PtCo core; however, the D-PtCo3/HSC catalyst is dominated by NPs with porous Pt shells surrounding multiple disordered PtCo cores with local concentration of Co. In situ X-ray absorption spectroscopy (XAS) reveals that these two catalysts possess similar Pt–Pt and Pt–Co bond distances and Pt coordination numbers (CNs), despite their dissimilar morphologies. The similar activity of the two catalysts is thus ascribed to their comparable strain, ligand, and particle size effects. Ex situ XAS performed on D-PtCo3/HSC under different voltage cycling stage shows that the continuous dissolution of Co leaves behind the NPs with a Pt-like structure after 30k cycles. The attenuated strain and/or ligand effects caused by Co dissolution are presumably counterbalanced by the particle size effects with particle growth, which likely accounts for the constant specific activity of the catalysts along with voltage cycling. PMID:26413384

  7. Strategies for Probing Nanometer-Scale Electrocatalysts: From Single Particles to Catalyst-Membrane Architectures

    Energy Technology Data Exchange (ETDEWEB)

    Korzeniewski, Carol [Texas Tech Univ., Lubbock, TX (United States). Department of Chemistry & Biochemistry

    2014-01-20

    The project primary objectives are to prepare and elucidate the promoting properties of materials that possess high activity for the conversion of hydrogen and related small molecules (water, oxygen, carbon monoxide and methanol) in polymer electrolyte fuel cells. One area of research has focused on the study of catalyst materials. Protocols were developed for probing the structure and benchmarking the activity of Pt and Pt bimetallic nanometer-scale catalyst against Pt single crystal electrode standards. A second area has targeted fuel cell membrane and the advancement of simple methods mainly based on vibrational spectroscopy that can be applied broadly in the study of membrane structure and transport properties. Infrared and Raman methods combined with least-squares data modeling were applied to investigate and assist the design of robust, proton conductive membranes, which resist reactant crossover.

  8. Morphology, composition, and mixing state of primary particles from combustion sources - crop residue, wood, and solid waste.

    Science.gov (United States)

    Liu, Lei; Kong, Shaofei; Zhang, Yinxiao; Wang, Yuanyuan; Xu, Liang; Yan, Qin; Lingaswamy, A P; Shi, Zongbo; Lv, Senlin; Niu, Hongya; Shao, Longyi; Hu, Min; Zhang, Daizhou; Chen, Jianmin; Zhang, Xiaoye; Li, Weijun

    2017-07-11

    Morphology, composition, and mixing state of individual particles emitted from crop residue, wood, and solid waste combustion in a residential stove were analyzed using transmission electron microscopy (TEM). Our study showed that particles from crop residue and apple wood combustion were mainly organic matter (OM) in smoldering phase, whereas soot-OM internally mixed with K in flaming phase. Wild grass combustion in flaming phase released some Cl-rich-OM/soot particles and cardboard combustion released OM and S-rich particles. Interestingly, particles from hardwood (pear wood and bamboo) and softwood (cypress and pine wood) combustion were mainly soot and OM in the flaming phase, respectively. The combustion of foam boxes, rubber tires, and plastic bottles/bags in the flaming phase released large amounts of soot internally mixed with a small amount of OM, whereas the combustion of printed circuit boards and copper-core cables emitted large amounts of OM with Br-rich inclusions. In addition, the printed circuit board combustion released toxic metals containing Pb, Zn, Sn, and Sb. The results are important to document properties of primary particles from combustion sources, which can be used to trace the sources of ambient particles and to know their potential impacts in human health and radiative forcing in the air.

  9. Modeling intraparticle transports during propylene polymerizations using supported metallocene and dual function metallocene as catalysts: Single particle model

    Directory of Open Access Journals (Sweden)

    Li Hua-Rong

    2014-01-01

    Full Text Available Two improved multigrain models (MGMs for preparing homopolypropylene and long chain branched polypropylene via propylene polymerization using silica-supported metallocene or dual function metallocene as catalysts are presented in this paper. The presented models are used to predict the intraparticle flow fields involved in the polymerizations. The simulation results show that the flow field distributions involve dare basically identical. The results also show that both the two polymerization processes have an initiation stage and the controlling step for them is reaction-diffusion-reaction with the polymerization proceeding. Furthermore, the simulation results show that the intra particle mass transfer resistance has significant effect on the polymerization but the heat transfer resistance can be ignored.

  10. In-vehicle measurement of ultrafine particles on compressed natural gas, conventional diesel, and oxidation-catalyst diesel heavy-duty transit buses.

    Science.gov (United States)

    Hammond, Davyda; Jones, Steven; Lalor, Melinda

    2007-02-01

    Many metropolitan transit authorities are considering upgrading transit bus fleets to decrease ambient criteria pollutant levels. Advancements in engine and fuel technology have lead to a generation of lower-emission buses in a variety of fuel types. Dynamometer tests show substantial reductions in particulate mass emissions for younger buses (vehicle particle number concentration measurements on conventional diesel, oxidation-catalyst diesel and compressed natural gas transit buses are compared to estimate relative in-vehicle particulate exposures. Two primary consistencies are observed from the data: the CNG buses have average particle count concentrations near the average concentrations for the oxidation-catalyst diesel buses, and the conventional diesel buses have average particle count concentrations approximately three to four times greater than the CNG buses. Particle number concentrations are also noticeably affected by bus idling behavior and ventilation options, such as, window position and air conditioning.

  11. The preparation of nanosized polyethylene particles via novel heterogeneous non-metallocene catalyst (m-CH3PhO)TiCl3/CNTs/AlEt3

    Science.gov (United States)

    Wang, J.; Guo, J. P.; Yi, J. J.; Huang, Q. G.; Li, H. M.; Li, Y. F.; Gao, K. J.; Yang, W. T.

    2014-08-01

    This paper reports the preparation of coral-shaped topological morphology nascent polyethylene (PE) particles promoted by the novel heterogeneous non-metallocene catalyst (m-CH3PhO)TiCl3/carbon nanotubes (CNTs), with AlEt3 used as a cocatalyst. Scanning electron microscope (SEM), high resolution transmission electron microscope (HR-TEM) and inductively coupled plasma (ICP) emission spectroscopy were used to determine the morphology of the catalyst particles and the content of (m-CH3PhO)TiCl3. The carbon nanotube surface was treated with Grignard Reagent prior to reacting with (m-CH3PhO)TiCl3. The catalyst system could effectively catalyze ethylene polymerization and ethylene with 1- hexene copolymerization, the catalytic activity could reach up to 5.8 kg/((gTi)h). Morphology of the obtained polymer particles by SEM and HR-TEM technique revealed that the nascent polyethylene particles looked like coral shape in micro-size. The multiwalled carbon nanotubes (MWCNTs) supported catalysts polymerized ethylene to form polymer nanocomposite in situ. The microscopic examination of this nanocomposite revealed that carbon nanoparticles in PE matrix had a good distribution and the cryogenically fractured surface was ductile-like when polymerization time was 2 min.

  12. The preparation of nanosized polyethylene particles via novel heterogeneous non-metallocene catalyst (m-CH3PhO)TiCl3/CNTs/AlEt3

    International Nuclear Information System (INIS)

    Wang, J; Guo, J P; Huang, Q G; Li, Y F; Yang, W T; Yi, J J; Li, H M; Gao, K J

    2014-01-01

    This paper reports the preparation of coral-shaped topological morphology nascent polyethylene (PE) particles promoted by the novel heterogeneous non-metallocene catalyst (m-CH 3 PhO)TiCl 3 /carbon nanotubes (CNTs), with AlEt 3 used as a cocatalyst. Scanning electron microscope (SEM), high resolution transmission electron microscope (HR-TEM) and inductively coupled plasma (ICP) emission spectroscopy were used to determine the morphology of the catalyst particles and the content of (m-CH 3 PhO)TiCl 3 . The carbon nanotube surface was treated with Grignard Reagent prior to reacting with (m-CH 3 PhO)TiCl 3 . The catalyst system could effectively catalyze ethylene polymerization and ethylene with 1- hexene copolymerization, the catalytic activity could reach up to 5.8 kg/((gTi)h). Morphology of the obtained polymer particles by SEM and HR-TEM technique revealed that the nascent polyethylene particles looked like coral shape in micro-size. The multiwalled carbon nanotubes (MWCNTs) supported catalysts polymerized ethylene to form polymer nanocomposite in situ. The microscopic examination of this nanocomposite revealed that carbon nanoparticles in PE matrix had a good distribution and the cryogenically fractured surface was ductile-like when polymerization time was 2 min

  13. How to Determine the Core-Shell Nature in Bimetallic Catalyst Particles?

    Directory of Open Access Journals (Sweden)

    Emma Westsson

    2014-11-01

    Full Text Available Nanometer-sized materials have significantly different chemical and physical properties compared to bulk material. However, these properties do not only depend on the elemental composition but also on the structure, shape, size and arrangement. Hence, it is not only of great importance to develop synthesis routes that enable control over the final structure but also characterization strategies that verify the exact nature of the nanoparticles obtained. Here, we consider the verification of contemporary synthesis strategies for the preparation of bimetallic core-shell particles in particular in relation to potential particle structures, such as partial absence of core, alloying and raspberry-like surface. It is discussed what properties must be investigated in order to fully confirm a covering, pin-hole free shell and which characterization techniques can provide such information. Not uncommonly, characterization strategies of core-shell particles rely heavily on visual imaging like transmission electron microscopy. The strengths and weaknesses of various techniques based on scattering, diffraction, transmission and absorption for investigating core-shell particles are discussed and, in particular, cases where structural ambiguities still remain will be highlighted. Our main conclusion is that for particles with extremely thin or mono-layered shells—i.e., structures outside the limitation of most imaging techniques—other strategies, not involving spectroscopy or imaging, are to be employed. We will provide a specific example of Fe-Pt core-shell particles prepared in bicontinuous microemulsion and point out the difficulties that arise in the characterization process of such particles.

  14. Lp-norm-residual constrained regularization model for estimation of particle size distribution in dynamic light scattering.

    Science.gov (United States)

    Zhu, Xinjun; Li, Jing; Thomas, John C; Song, Limei; Guo, Qinghua; Shen, Jin

    2017-07-01

    In particle size measurement using dynamic light scattering (DLS), noise makes the estimation of the particle size distribution (PSD) from the autocorrelation function data unreliable, and a regularization technique is usually required to estimate a reasonable PSD. In this paper, we propose an Lp-norm-residual constrained regularization model for the estimation of the PSD from DLS data based on the Lp norm of the fitting residual. Our model is a generalization of the existing, commonly used L2-norm-residual-based regularization methods such as CONTIN and constrained Tikhonov regularization. The estimation of PSDs by the proposed model, using different Lp norms of the fitting residual for p=1, 2, 10, and ∞, is studied and their performance is determined using simulated and experimental data. Results show that our proposed model with p=1 is less sensitive to noise and improves stability and accuracy in the estimation of PSDs for unimodal and bimodal systems. The model with p=1 is particularly applicable to the noisy or bimodal PSD cases.

  15. Catalyst systems in the production of biodiesel from residual oil; Sistemas cataliticos na producao de biodiesel por meio de oleo residual

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Carlos Alexandre de [Universidade Federal de Itajuba (UNIFEI), MG (Brazil)

    2006-07-01

    The vegetable oils and fat animals appear like an alternative for substitution the diesel oil in ignition engines for compression. Submitting the oil on transesterification reaction, we obtain a fuel with same characteristics as diesel, called biodiesel. Generally, 85 per cent of biodiesel cost is from the oil production. Through transesterification vegetable oil can be transformed in a mixture of esters of fatty acids. The residual oil from frying has been used as a possibility of raw materials of biodiesel, due to its easy acquisition and the viability of not being discarded as waste. (author)

  16. Catalytic combustion of diesel soot particles. Activity and characterization of Co/MgO and Co,K/MgO catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Querini, C.A.; Ulla, M.A.; Sedran, U.A.; Miro, E.E. [Instituto de Investigaciones en Catalisis y Petroquimica - INCAPE, Santa Fe (Argentina); Requejo, F. [Departamento de Fisica, Fac. de Ciencias Exactas, UNLP, La Plata (Argentina); Soria, J. [Instituto de Catalisis y Petroleoquimica, Madrid (Spain)

    1998-01-15

    The catalytic combustion of diesel soot particles was studied on Co/MgO (12wt% Co) and potassium-promoted Co/MgO (1.5wt% K) that were calcined at different temperatures in the 300 to 700C range. Catalyst samples were characterized by various techniques including nitrogen adsorption (BET), temperature programmed reduction (TPR), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), electron spin resonance (ESR), X-ray photoelectron spectroscopy (XPS) and temperature programmed oxidation (TPO). As observed by TPO experiments, the catalyst activity depends strongly on the calcination temperature: calcination at 300 and 400C produced samples that were much more active than those calcined at higher temperatures, on which an inactive Mg-Co mixed oxide is formed, as suggested by TPR, ESR and XRD results. FTIR shows carbonate species on the surface. Unpromoted samples seem to correlate their activity with the amount of reducible Co species present. Potassium not only increased the sample activity, probably due to the improvement in surface mobility, but also enhanced stability at high temperatures. Experiments with different soot to catalyst ratios showed no significant variation in combustion temperature. The K-promoted catalyst burns off soot at a temperature lower than the one needed for calcination, thus proving to be a promising catalyst

  17. Ziegler-Natta Catalyst Based on MgCl₂/Clay/ID/TiCl₄ for the Synthesis of Spherical Particles of Polypropylene Nanocomposites.

    Science.gov (United States)

    Cardoso, Renata da Silva; Oliveira, Jaqueline da Silva; Ramis, Luciana Bortolin; Marques, Maria de Fátima V

    2018-07-01

    In the present work, we have designed MgCl2/clay/internal donor (ID)/TiCl4 based bisupported Ziegler-Natta catalysts containing varying amounts of organoclay (montmorillonite) in order to synthesize spherical particles of polypropylene/clay nanocomposites (PCN). The organoclay was introduced into the catalyst support formulation and PCN was obtained using the in situ polymerization technique. Decreasing the reaction time, it was possible to obtain nanocomposites with high concentrations of clay (masterbatches). Micrographs of SEM confirmed the spherical morphology of the catalysts. In addition, XRD patterns show that the active sites for polymerization were inserted in the clay galleries. The catalytic performance was evaluated in slurry propylene polymerization using triethylaluminium as cocatalyst and silane as external electron donor at 70 °C, 4 bar, and different reaction times. The PCNs obtained containing different clay amounts were characterized by X-ray diffraction, thermal analyses, transmission electronic microscopy, and extractables in heptane. The results revealed that the synthesized PP/clay particles were also spherical showing that the morphological control is possible even using catalysts containing high amounts of clay. The PCN presented high degradation temperature (459 °C). The XRD peak related to the clay interlamellar distance has shifted to lower angles, and TEM images confirmed the formation of exfoliated/intercalated clay on the PP matrix and absence of microparticles of clay.

  18. Synthesis of Supported Ultrafine Non-noble Subnanometer-Scale Metal Particles Derived from Metal-Organic Frameworks as Highly Efficient Heterogeneous Catalysts.

    Science.gov (United States)

    Kang, Xinchen; Liu, Huizhen; Hou, Minqiang; Sun, Xiaofu; Han, Hongling; Jiang, Tao; Zhang, Zhaofu; Han, Buxing

    2016-01-18

    The properties of supported non-noble metal particles with a size of less than 1 nm are unknown because their synthesis is a challenge. A strategy has now been created to immobilize ultrafine non-noble metal particles on supports using metal-organic frameworks (MOFs) as metal precursors. Ni/SiO2 and Co/SiO2 catalysts were synthesized with an average metal particle size of 0.9 nm. The metal nanoparticles were immobilized uniformly on the support with a metal loading of about 20 wt%. Interestingly, the ultrafine non-noble metal particles exhibited very high activity for liquid-phase hydrogenation of benzene to cyclohexane even at 80 °C, while Ni/SiO2 with larger Ni particles fabricated by a conventional method was not active under the same conditions. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Fine particle clay catalysts for coal liquefaction. Quarterly technical progress report, May 9, 1992--August 8, 1992

    Energy Technology Data Exchange (ETDEWEB)

    Olson, E.S.

    1995-10-01

    An investigation of new methods for the production of mixed pillared clay catalysts and clay-supported catalysts and determination of their catalytic activities were continued in this quarter. To demonstrate the reproducibility of the preparative method for high activity iron/alumina-pillared montmorillonite catalysts, a new batch of the catalyst was prepared and tested for hydrocracking activity with bibenzyl. This preparation gave conversion and product distribution similar to that reported previously. The mixed iron/alumina-pillared clay was also prepared using a pillaring solution that was aged for longer period of time. To determine the importance of the type of pillaring support in hydrocracking activity, iron/zirconia-pillared montmorillonite was prepared using the same technique as that for iron/alumina-pillared montmorillonite. The reaction of bibenzyl with the sulfided iron/zirconia-pillared catalyst gave a lower hydrocracking conversion than the iron/alumina-pillared catalyst. Addition of a second catalytic metal to the clay support was attempted to determine if a synergistic effect could improve liquefaction. Ferric nitrate and stannous chloride were added to the clay, but the resulting catalyst was relatively poor for hydrocracking and hydrogenation compared with ferric nitrate supported on the clay. New disposable iron catalysts with high acidity and surface area are desired for coal liquefaction. Synthetic iron aluminosilicates were prepared by methods similar to those used for the nickel-substituted synthetic mica montmorillonite (NiSMM) catalysts, which are very effective for hydrogenation and reforming of hydrocarbons. The iron aluminosilicate catalysts were tested for hydrocracking and hydrogenation of bibenzyl, naphthalene and pyrene. Pyrene hydrogenation was effectively catalyzed by the sulfided synthetic iron catalyst.

  20. Chemical characterization of individual particles and residuals of cloud droplets and ice crystals collected on board research aircraft in the ISDAC 2008 study

    Science.gov (United States)

    Hiranuma, N.; Brooks, S. D.; Moffet, R. C.; Glen, A.; Laskin, A.; Gilles, M. K.; Liu, P.; MacDonald, A. M.; Strapp, J. W.; McFarquhar, G. M.

    2013-06-01

    Ambient particles and the dry residuals of mixed-phase cloud droplets and ice crystals were collected during the Indirect and Semi-Direct Aerosol Campaign (ISDAC) near Barrow, Alaska, in spring of 2008. The collected particles were analyzed using Computer Controlled Scanning Electron Microscopy with Energy Dispersive X-ray analysis and Scanning Transmission X-ray Microscopy coupled with Near Edge X-ray Absorption Fine Structure spectroscopy to identify physico-chemical properties that differentiate cloud-nucleating particles from the total aerosol population. A wide range of individually mixed components was identified in the ambient particles and residuals including organic carbon compounds, inorganics, carbonates, and black carbon. Our results show that cloud droplet residuals differ from the ambient particles in both size and composition, suggesting that both properties may impact the cloud-nucleating ability of aerosols in mixed-phase clouds. The percentage of residual particles which contained carbonates (47%) was almost four times higher than those in ambient samples. Residual populations were also enhanced in sea salt and black carbon and reduced in organic compounds relative to the ambient particles. Further, our measurements suggest that chemical processing of aerosols may improve their cloud-nucleating ability. Comparison of results for various time periods within ISDAC suggests that the number and composition of cloud-nucleating particles over Alaska can be influenced by episodic events bringing aerosols from both the local vicinity and as far away as Siberia.

  1. 40 CFR Appendix A to Subpart Uuu... - Determination of Metal Concentration on Catalyst Particles (Instrumental Analyzer Procedure)

    Science.gov (United States)

    2010-07-01

    ... Pollutants for Petroleum Refineries: Catalytic Cracking Units, Catalytic Reforming Units, and Sulfur Recovery... catalytic cracking unit (FCCU) regenerator (i.e., equilibrium catalyst), from air pollution control systems operated for the FCCU catalyst regenerator vent (FCCU fines), from catalytic reforming units (CRU), and...

  2. Nanosized ruthenium particles decorated carbon nanofibers as active catalysts for the oxidation of p-cymene by molecular oxygen

    CSIR Research Space (South Africa)

    Makgwane, PR

    2013-07-01

    Full Text Available catalysts was influenced by the structural properties that resulted from the different metal loadings and by various reaction variables, such as the temperature, the amount of catalyst and the type of radical–initiator substrate. Under optimized reaction...

  3. Effect of the nanosized TiO2 particles in Pd/C catalysts as cathode materials in direct methanol fuel cells.

    Science.gov (United States)

    Choi, Mahnsoo; Han, Choonsoo; Kim, In-Tae; Lee, Ji-Jung; Lee, Hong-Ki; Shim, Joongpyo

    2011-07-01

    Pd-TiO2/C catalysts were prepared by impregnating titanium dioxide (TiO2) on carbon-supported Pd (Pd/C) for use as the catalyst for the oxygen reduction reaction (ORR) in direct methanol fuel cells (DMFCs). Transmission electron microscope (TEM), scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses were carried to confirm the distribution, morphology and structure of Pd and TiO2 on the carbon support. In fuel cell test, we confirmed that the addition of TiO2 nanoparticles make the improved catalytic activity of oxygen reduction. The electrochemical characterization of the Pd-TiO2/C catalyst for the ORR was carried out by cyclic voltammetry (CV) in the voltage window of 0.04 V to 1.2 V with scan rate of 25 mV/s. With the increase in the crystallite size of TiO2, the peak potential for OH(ads) desorption on the surface of Pd particle shifted to higher potential. This implies that TiO2 might affect the adsorption and desorption of oxygen molecules on Pd catalyst. The performance of Pd-TiO2/C as a cathode material was found to be similar to or better performance than that of Pt/C.

  4. Oxidation catalysts on alkaline earth supports

    Science.gov (United States)

    Mohajeri, Nahid

    2017-03-21

    An oxidation catalyst includes a support including particles of an alkaline earth salt, and first particles including a palladium compound on the support. The oxidation catalyst can also include precious metal group (PMG) metal particles in addition to the first particles intermixed together on the support. A gas permeable polymer that provides a continuous phase can completely encapsulate the particles and the support. The oxidation catalyst may be used as a gas sensor, where the first particles are chemochromic particles.

  5. Titania Supported Pt and Pt/Pd Nano-particle Catalysts for the Oxidation of Sulfur Dioxide

    DEFF Research Database (Denmark)

    Koutsopoulos, Sotiris; Johannessen, Tue; Eriksen, Kim Michael

    2006-01-01

    Several types of titania (anatase) were used as supports for pure platinum and Pt–Pd bimetallic alloy catalysts. The preparation methods, normal wet impregnation technique and flame aerosol synthesis, obtained metal loadings of 2% by weight. The prepared catalysts were tested for SO2 oxidation...... activity at atmospheric pressure in the temperature range 250–600 °C. The SO2 to SO3 conversion efficiency of the Pt–Pd alloy was significantly higher than that of the individual metals. The effects of the preparation method and the titania type used on the properties and activity of the resulting catalyst...

  6. Oxide-supported IrNiO(x) core-shell particles as efficient, cost-effective, and stable catalysts for electrochemical water splitting.

    Science.gov (United States)

    Nong, Hong Nhan; Oh, Hyung-Suk; Reier, Tobias; Willinger, Elena; Willinger, Marc-Georg; Petkov, Valeri; Teschner, Detre; Strasser, Peter

    2015-03-02

    Active and highly stable oxide-supported IrNiO(x) core-shell catalysts for electrochemical water splitting are presented. IrNi(x)@IrO(x) nanoparticles supported on high-surface-area mesoporous antimony-doped tin oxide (IrNiO(x)/Meso-ATO) were synthesized from bimetallic IrNi(x) precursor alloys (PA-IrNi(x) /Meso-ATO) using electrochemical Ni leaching and concomitant Ir oxidation. Special emphasis was placed on Ni/NiO surface segregation under thermal treatment of the PA-IrNi(x)/Meso-ATO as well as on the surface chemical state of the particle/oxide support interface. Combining a wide array of characterization methods, we uncovered the detrimental effect of segregated NiO phases on the water splitting activity of core-shell particles. The core-shell IrNiO(x)/Meso-ATO catalyst displayed high water-splitting activity and unprecedented stability in acidic electrolyte providing substantial progress in the development of PEM electrolyzer anode catalysts with drastically reduced Ir loading and significantly enhanced durability. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Integrated Transmission Electron and Single-Molecule Fluorescence Microscopy Correlates Reactivity with Ultrastructure in a Single Catalyst Particle

    NARCIS (Netherlands)

    Hendriks, Frank C.|info:eu-repo/dai/nl/412642697; Mohammadian, Sajjad|info:eu-repo/dai/nl/374721327; Ristanovic, Zoran|info:eu-repo/dai/nl/328233005; Kalirai, Samanbir; Meirer, Florian; Vogt, Eelco T. C.|info:eu-repo/dai/nl/073717398; Bruijnincx, Pieter C. A.|info:eu-repo/dai/nl/33799529X; Gerritsen, Hans|info:eu-repo/dai/nl/071548777; Weckhuysen, Bert M.|info:eu-repo/dai/nl/285484397

    2018-01-01

    Establishing structure–activity relationships in complex, hierarchically structured nanomaterials, such as fluid catalytic cracking (FCC) catalysts, requires characterization with complementary, correlated analysis techniques. An integrated setup has been developed to perform transmission electron

  8. Photocatalytic degradation of rhodamine B, paracetamol and diclofenac sodium by supported titania-based catalysts from petrochemical residue: effect of doping with magnesium.

    Science.gov (United States)

    da Silva, William Leonardo; Lansarin, Marla Azário; Dos Santos, João Henrique Z; Silveira, Fernando

    2016-11-01

    Three different lots of a residual Ziegler-Natta catalyst slurry (bearing Ti and Mg) obtained from an industrial petrochemical plant were employed as sources for the photocatalyst supported on silica. The effect of additional magnesium (1.0-25.0 wt% Mg/SiO 2 ) on the photocatalytic properties of the doped materials was investigated. Doping the titania-based photocatalyst with Mg results in a shift in the absorption threshold toward the visible spectrum. The optical band gap energy of the bare supported photocatalyst was in the range of 2.5 eV and shifted to 1.72 eV after 25 wt% Mg doping. The systems were evaluated for the photodegradation of one dye (rhodamine B (RhB)) and two drugs (paracetamol and diclofenac sodium) either under ultraviolet (UV) (365 nm - UVA) or visible radiation, separately. Among the evaluated systems, doping with 25 wt% Mg afforded the highest degradation values for the target molecules under UV and visible radiation (i.e. 87%, 60% and 55% of the RhB, paracetamol and diclofenac under UV, respectively, and 82%, 48.3% and 48% under visible irradiation, respectively).

  9. The Relationship Between the Surface Morphology and Chemical Composition of Gunshot Residue Particles.

    Science.gov (United States)

    Kara, Ilker; Lisesivdin, Sefer Bora; Kasap, Mehmet; Er, Elif; Uzek, Ugur

    2015-07-01

    In this study, chemical composition and morphology of gunshot residue (GSR) of 9 × 19 mm Parabellum-type MKE (Turkey)-brand ammunition were analyzed by scanning electron microscope and energy dispersive X-ray spectrometer. GSR samples were collected by "swab" technique from the shooter's right hand immediately after shooting. According to general principles of thermodynamics, it is likely that the structures will have a more regular (homogeneous) spherical form to minimize their surface area due to very high temperatures and pressures that occur during explosion. Studied samples were collected under the same conditions with the same original ammunition, from the same firearm and a single shooter. This is because many other variables may affect size, structure, and composition in addition to the concentrations of elements of the structure. Results indicated that the chemical compositions are effective in the formation of GSR morphological structures. © 2015 American Academy of Forensic Sciences.

  10. Magnetic catalyst bodies

    NARCIS (Netherlands)

    Teunissen, Wendy; Bol, A.A.; Geus, John W.

    1999-01-01

    After a discussion about the importance of the size of the catalyst bodies with reactions in the liquid-phase with a suspended catalyst, the possibilities of magnetic separation are dealt with. Deficiencies of the usual ferromagnetic particles are the reactivity and the clustering of the

  11. Identifying SARS-CoV membrane protein amino acid residues linked to virus-like particle assembly.

    Directory of Open Access Journals (Sweden)

    Ying-Tzu Tseng

    Full Text Available Severe acute respiratory syndrome coronavirus (SARS-CoV membrane (M proteins are capable of self-assembly and release in the form of membrane-enveloped vesicles, and of forming virus-like particles (VLPs when coexpressed with SARS-CoV nucleocapsid (N protein. According to previous deletion analyses, M self-assembly involves multiple M sequence regions. To identify important M amino acid residues for VLP assembly, we coexpressed N with multiple M mutants containing substitution mutations at the amino-terminal ectodomain, carboxyl-terminal endodomain, or transmembrane segments. Our results indicate that a dileucine motif in the endodomain tail (218LL219 is required for efficient N packaging into VLPs. Results from cross-linking VLP analyses suggest that the cysteine residues 63, 85 and 158 are not in close proximity to the M dimer interface. We noted a significant reduction in M secretion due to serine replacement for C158, but not for C63 or C85. Further analysis suggests that C158 is involved in M-N interaction. In addition to mutations of the highly conserved 107-SWWSFNPE-114 motif, substitutions at codons W19, W57, P58, W91, Y94 or F95 all resulted in significantly reduced VLP yields, largely due to defective M secretion. VLP production was not significantly affected by a tryptophan replacement of Y94 or F95 or a phenylalanine replacement of W19, W57 or W91. Combined, these results indicate the involvement of specific M amino acids during SARS-CoV virus assembly, and suggest that aromatic residue retention at specific positions is critical for M function in terms of directing virus assembly.

  12. Environmental Transmission Electron Microscopy Study of the Origins of Anomalous Particle Size Distributions in Supported Metal Catalysts

    DEFF Research Database (Denmark)

    Benavidez, Angelica D.; Kovarik, Libor; Genc, Arda

    2012-01-01

    In this Environmental Transmission Electron Microscopy (ETEM) study we examined the growth patterns of uniform distributions of nanoparticles (NPs) using model catalysts. Pt/SiO2 was heated at 550 °C in 560 Pa of O2 while Pd/carbon was heated in vacuum at 500 °C and in 300 Pa of 5%H2 in Argon...

  13. Integrated Transmission Electron and Single‐Molecule Fluorescence Microscopy Correlates Reactivity with Ultrastructure in a Single Catalyst Particle

    OpenAIRE

    Hendriks, Frank C.; Mohammadian, Sajjad; Ristanović, Zoran; Kalirai, Sam; Meirer, Florian; Vogt, Eelco T. C.; Bruijnincx, Pieter C. A.; Gerritsen, Hans C.; Weckhuysen, Bert M.

    2017-01-01

    Abstract Establishing structure–activity relationships in complex, hierarchically structured nanomaterials, such as fluid catalytic cracking (FCC) catalysts, requires characterization with complementary, correlated analysis techniques. An integrated setup has been developed to perform transmission electron microscopy (TEM) and single‐molecule fluorescence (SMF) microscopy on such nanostructured samples. Correlated structure–reactivity information was obtained for 100 nm thin, microtomed secti...

  14. Integrated Transmission Electron and Single-Molecule Fluorescence Microscopy Correlates Reactivity with Ultrastructure in a Single Catalyst Particle

    OpenAIRE

    Hendriks, Frank C.; Mohammadian, Sajjad; Ristanovic, Zoran; Kalirai, Samanbir; Meirer, Florian; Vogt, Eelco T. C.; Bruijnincx, Pieter C. A.; Gerritsen, Hans; Weckhuysen, Bert M.

    2018-01-01

    Establishing structure–activity relationships in complex, hierarchically structured nanomaterials, such as fluid catalytic cracking (FCC) catalysts, requires characterization with complementary, correlated analysis techniques. An integrated setup has been developed to perform transmission electron microscopy (TEM) and single-molecule fluorescence (SMF) microscopy on such nanostructured samples. Correlated structure–reactivity information was obtained for 100 nm thin, microtomed sections of a ...

  15. Rattle-type hierarchical particles containing multilevel cores (Ag@AgCl@SiO2 and Au/Ag@AgCl@SiO2) as versatile catalysts.

    Science.gov (United States)

    Huy, Do Xuan; Lee, Ha-Jin; Lee, Young Boo; Choi, Won San

    2014-07-01

    A protocol for the synthesis of rattle-type core@shell particles containing Ag@AgCl or Au/Ag@AgCl core structures was developed, and the use of these particles as catalysts for the decomposition of toxic materials was demonstrated. A monometallic Ag or bimetallic Au/Ag core was incorporated into the interior of SiO2 capsules via controlled heat treatment of metal nanoparticle/SiO2-coated polymer particles, resulting in the formation of rattle-type core@shell structures. By appropriate treatments, it was possible to transform the Ag or Au/Ag core into multilevel cores (Ag@AgCl or Au/Ag@AgCl) within the SiO2 capsules (Ag@AgCl@SiO2 or Au/Ag@AgCl@SiO2). This method for the synthesis of rattle-type core@shell particles is useful for further introducing AgCl fused with plasmonic materials into the capsule structures. The rattle-type core@shell structures were used as photocatalysts for the decomposition of organic pollutants such as methyl orange. Furthermore, these nanocatalysts containing semiconductors such as AgCl were also applied toward the reduction of nitrophenol (NPh) to aminophenol (APh). The Ag@AgCl@SiO2 or Au/Ag@AgCl@SiO2 catalysts showed excellent catalytic properties in the decomposition of toxic substances in terms of their activity and reusability. Copyright © 2014 Elsevier Inc. All rights reserved.

  16. Residual sweeping errors in turbulent particle pair diffusion in a Lagrangian diffusion model.

    Directory of Open Access Journals (Sweden)

    Nadeem A Malik

    Full Text Available Thomson, D. J. & Devenish, B. J. [J. Fluid Mech. 526, 277 (2005] and others have suggested that sweeping effects make Lagrangian properties in Kinematic Simulations (KS, Fung et al [Fung J. C. H., Hunt J. C. R., Malik N. A. & Perkins R. J. J. Fluid Mech. 236, 281 (1992], unreliable. However, such a conclusion can only be drawn under the assumption of locality. The major aim here is to quantify the sweeping errors in KS without assuming locality. Through a novel analysis based upon analysing pairs of particle trajectories in a frame of reference moving with the large energy containing scales of motion it is shown that the normalized integrated error [Formula: see text] in the turbulent pair diffusivity (K due to the sweeping effect decreases with increasing pair separation (σl, such that [Formula: see text] as σl/η → ∞; and [Formula: see text] as σl/η → 0. η is the Kolmogorov turbulence microscale. There is an intermediate range of separations 1 < σl/η < ∞ in which the error [Formula: see text] remains negligible. Simulations using KS shows that in the swept frame of reference, this intermediate range is large covering almost the entire inertial subrange simulated, 1 < σl/η < 105, implying that the deviation from locality observed in KS cannot be atributed to sweeping errors. This is important for pair diffusion theory and modeling. PACS numbers: 47.27.E?, 47.27.Gs, 47.27.jv, 47.27.Ak, 47.27.tb, 47.27.eb, 47.11.-j.

  17. Towards a highly-efficient fuel-cell catalyst: optimization of Pt particle size, supports and surface-oxygen group concentration.

    Science.gov (United States)

    Muthuswamy, Navaneethan; de la Fuente, Jose Luis Gomez; Ochal, Piotr; Giri, Rajiv; Raaen, Steinar; Sunde, Svein; Rønning, Magnus; Chen, De

    2013-03-21

    In the present work, methanol oxidation reaction was investigated on Pt particles of various diameters on carbon-nanofibers and carbon-black supports with different surface-oxygen concentrations, aiming for a better understanding of the relationship between the catalyst properties and the electrochemical performance. The pre-synthesized Pt nanoparticles in ethylene glycol, prepared by the polyol method without using any capping agents, were deposited on different carbon supports. Removal of oxygen-groups from the carbon supports had profound positive effects on not only the Pt dispersion but also the specific activity. The edge structures on the stacked graphene sheets in the platelet carbon-nanofibers provided a strong interaction with the Pt particles, significantly reconstructing them in the process. Such reconstruction resulted in the formation of more plated Pt particles on the CNF than on the carbon-black and exposure of more Pt atoms with relatively high co-ordination numbers, and thereby higher specific activity. Owing to the combined advantages of optimum Pt particle diameter, an oxygen-free surface and the unique properties of CNFs, Pt supported on heat-treated CNFs exhibited a higher mass activity twice of that of its commercial counterpart.

  18. Gamma-ray application to the measurement of a media distribution at the catalyst cooler of a residue fluid catalytic cracking unit (RFCCU) in the petrochemical industry

    International Nuclear Information System (INIS)

    Kim, Jin Seop; Jung, Sung Hee; Kim, Jong Bum

    2006-01-01

    The dynamic behavior of the process media in the petrochemical industry can hardly be observed during its operation. Because the information on the process media is directly related to the processes efficiency, therefore it is necessary to establish what is actually happening inside the process unit. For this purpose, a field experiment was performed to study the fluidized catalyst patterns and confirm the internal conditions by using a sealed gamma-ray source. From the results, the areas showing a different pattern from the surrounding vicinity were found successfully. Especially at the upper part of the connection point at which the pipeline from are generator was joined, a relatively low amount of catalyst was distributed. Sealed gamma-ray application to the catalyst cooler is considered as a worthwhile technique for a measurement of the catalyst distribution at the RFCCU.

  19. Oxidation catalyst

    Science.gov (United States)

    Ceyer, Sylvia T.; Lahr, David L.

    2010-11-09

    The present invention generally relates to catalyst systems and methods for oxidation of carbon monoxide. The invention involves catalyst compositions which may be advantageously altered by, for example, modification of the catalyst surface to enhance catalyst performance. Catalyst systems of the present invention may be capable of performing the oxidation of carbon monoxide at relatively lower temperatures (e.g., 200 K and below) and at relatively higher reaction rates than known catalysts. Additionally, catalyst systems disclosed herein may be substantially lower in cost than current commercial catalysts. Such catalyst systems may be useful in, for example, catalytic converters, fuel cells, sensors, and the like.

  20. Thermodynamic analysis and chemical vapor deposition of multi-walled carbon nanotubes from pre-heated CH4 using Fe2O3 particles as catalyst precursor

    Science.gov (United States)

    Altay, Melek Cumbul; Eroglu, Serafettin

    2013-02-01

    The present study aims to investigate influence of pre-heating of CH4 on the growth of multi-walled carbon nanotubes (MWCNTs) using Fe2O3 particles as catalyst precursor. Equilibrium thermodynamic analyses in the systems of FeCOH and CH were performed to better understand the reduction of Fe2O3 by CH4 and to identify intermediate species which might promote growth of MWCNTs at the temperature range of 1000-1300 K. It was found that CH4 acted as reducing agent for Fe2O3 catalyst precursor which transformed to Fe3O4, FeO, Fe and Fe3C phases. This result was found to be in agreement with the thermodynamic prediction at 1200 and 1300 K. SEM-EDS analysis revealed that un-preheated CH4 yielded MWCNTs at 1200 K and a dense C coating at 1300 K. It was also observed that carbon was not formed at temperatures in the range of 1050-1150 K. Whereas, MWCNTs were grown at this temperature range from CH4 pre-heated at 1200 K. This result was attributed to the intermediate hydrocarbons, especially to C6H6, formed during pre-heating stage as thermodynamic analysis suggested. Mean diameter of the synthesized tubes was found to increase with growth time and temperature.

  1. PLASTIC WASTE CONVERSION TO LIQUID FUELS OVER MODIFIED-RESIDUAL CATALYTIC CRACKING CATALYSTS: MODELING AND OPTIMIZATION USING HYBRID ARTIFICIAL NEURAL NETWORK – GENETIC ALGORITHM

    Directory of Open Access Journals (Sweden)

    Istadi Istadi

    2012-04-01

    Full Text Available The plastic waste utilization can be addressed toward different valuable products. A promising technology for the utilization is by converting it to fuels. Simultaneous modeling and optimization representing effect of reactor temperature, catalyst calcinations temperature, and plastic/catalyst weight ratio toward performance of liquid fuel production was studied over modified catalyst waste. The optimization was performed to find optimal operating conditions (reactor temperature, catalyst calcination temperature, and plastic/catalyst weight ratio that maximize the liquid fuel product. A Hybrid Artificial Neural Network-Genetic Algorithm (ANN-GA method was used for the modeling and optimization, respectively. The variable interaction between the reactor temperature, catalyst calcination temperature, as well as plastic/catalyst ratio is presented in surface plots. From the GC-MS characterization, the liquid fuels product was mainly composed of C4 to C13 hydrocarbons.KONVERSI LIMBAH PLASTIK MENJADI BAHAN BAKAR CAIR DENGAN METODE PERENGKAHAN KATALITIK MENGGUNAKAN KATALIS BEKAS YANG TERMODIFIKASI: PEMODELAN DAN OPTIMASI MENGGUNAKAN GABUNGAN METODE ARTIFICIAL NEURAL NETWORK DAN GENETIC ALGORITHM. Pemanfaatan limbah plastik dapat dilakukan untuk menghasilkan produk yang lebih bernilai tinggi. Salah satu teknologi yang menjanjikan adalah dengan mengkonversikannya menjadi bahan bakar. Permodelan, simulasi dan optimisasi simultan yang menggambarkan efek dari suhu reaktor, suhu kalsinasi katalis, dan rasio berat plastik/katalis terhadap kinerja produksi bahan bakar cair telah dipelajari menggunakan katalis bekas termodifikasi Optimisasi ini ditujukan untuk mencari kondisi operasi optimum (suhu reaktor, suhu kalsinasi katalis, dan rasio berat plastik/katalis yang memaksimalkan produk bahan bakar cair. Metode Hybrid Artificial Neural Network-Genetic Algorithm (ANN-GA telah digunakan untuk permodelan dan optimisasi simultan tersebut. Inetraksi antar variabel

  2. Nitrous oxide and N-leaching losses from agricultural soil: Influence of crop residue particle size, quality and placement

    DEFF Research Database (Denmark)

    Ambus, P.; Jensen, E.S.; Robertson, G.P.

    2001-01-01

    Incorporation of crop residues provides a source of readily available C and N, and previous works indicate that farming strategies where crop residues are used for soil fertility purposes may lead to increased emissions of N2O. Information on the importance of different residue management on the ...

  3. Plasma-catalyst hybrid reactor with CeO2/γ-Al2O3 for benzene decomposition with synergetic effect and nano particle by-product reduction.

    Science.gov (United States)

    Mao, Lingai; Chen, Zhizong; Wu, Xinyue; Tang, Xiujuan; Yao, Shuiliang; Zhang, Xuming; Jiang, Boqiong; Han, Jingyi; Wu, Zuliang; Lu, Hao; Nozaki, Tomohiro

    2018-04-05

    A dielectric barrier discharge (DBD) catalyst hybrid reactor with CeO 2 /γ-Al 2 O 3 catalyst balls was investigated for benzene decomposition at atmospheric pressure and 30 °C. At an energy density of 37-40 J/L, benzene decomposition was as high as 92.5% when using the hybrid reactor with 5.0wt%CeO 2 /γ-Al 2 O 3 ; while it was 10%-20% when using a normal DBD reactor without a catalyst. Benzene decomposition using the hybrid reactor was almost the same as that using an O 3 catalyst reactor with the same CeO 2 /γ-Al 2 O 3 catalyst, indicating that O 3 plays a key role in the benzene decomposition. Fourier transform infrared spectroscopy analysis showed that O 3 adsorption on CeO 2 /γ-Al 2 O 3 promotes the production of adsorbed O 2 - and O 2 2‒ , which contribute benzene decomposition over heterogeneous catalysts. Nano particles as by-products (phenol and 1,4-benzoquinone) from benzene decomposition can be significantly reduced using the CeO 2 /γ-Al 2 O 3 catalyst. H 2 O inhibits benzene decomposition; however, it improves CO 2 selectivity. The deactivated CeO 2 /γ-Al 2 O 3 catalyst can be regenerated by performing discharges at 100 °C and 192-204 J/L. The decomposition mechanism of benzene over CeO 2 /γ-Al 2 O 3 catalyst was proposed. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Advanced Petroleum-Based Fuels - Diesel Emissions Project (APBF-DEC): 2,000-Hour Performance of a NOx Adsorber Catalyst and Diesel Particle Filter System for a Medium-Duty, Pick-Up Diesel Engine Platform; Final Report

    Energy Technology Data Exchange (ETDEWEB)

    2007-03-01

    Presents the results of a 2,000-hour test of an emissions control system consisting of a nitrogen oxides adsorber catalyst in combination with a diesel particle filter, advanced fuels, and advanced engine controls in an SUV/pick-up truck vehicle platform.

  5. Nitrous oxide and N-leaching losses from agricultural soil: Influence of crop residue particle size, quality and placement

    DEFF Research Database (Denmark)

    Ambus, P.; Jensen, E.S.; Robertson, G.P.

    2001-01-01

    protection of the crop residue material against microbial attack. Leaching of N tended to be reduced about 40 % with barley and 20 % with pea, but the numbers were not significantly different from residue-free soil, which leached 4.7-4.9 g N m(-2). When wheat and alfalfa residues were mixed into the soil N2O...... emissions increased 6.5 and 1.6 times, respectively, compared with residue placed in a layer. Wheat residue in a layer evolved 3.4-times less N2O than alfalfa in a layer, whereas when mixed the two residue types evolved similar amounts of N2O. This difference was probably due to N-limitations in localised...

  6. Residue processing

    Energy Technology Data Exchange (ETDEWEB)

    Gieg, W.; Rank, V.

    1942-10-15

    In the first stage of coal hydrogenation, the liquid phase, light and heavy oils were produced; the latter containing the nonliquefied parts of the coal, the coal ash, and the catalyst substances. It was the problem of residue processing to extract from these so-called let-down oils that which could be used as pasting oils for the coal. The object was to obtain a maximum oil extraction and a complete removal of the solids, because of the latter were returned to the process they would needlessly burden the reaction space. Separation of solids in residue processing could be accomplished by filtration, centrifugation, extraction, distillation, or low-temperature carbonization (L.T.C.). Filtration or centrifugation was most suitable since a maximum oil yield could be expected from it, since only a small portion of the let-down oil contained in the filtration or centrifugation residue had to be thermally treated. The most satisfactory centrifuge at this time was the Laval, which delivered liquid centrifuge residue and centrifuge oil continuously. By comparison, the semi-continuous centrifuges delivered plastic residues which were difficult to handle. Various apparatus such as the spiral screw kiln and the ball kiln were used for low-temperature carbonization of centrifuge residues. Both were based on the idea of carbonization in thin layers. Efforts were also being made to produce electrode carbon and briquette binder as by-products of the liquid coal phase.

  7. Particle size dependence on oxygen reduction reaction activity of electrodeposited TaOx catalysts in acidic media

    KAUST Repository

    Seo, J.

    2013-11-13

    The size dependence of the oxygen reduction reaction activity was studied for TaOx nanoparticles electrodeposited on carbon black for application to polymer electrolyte fuel cells (PEFCs). Compared with a commercial Ta2O5 material, the ultrafine oxide nanoparticles exhibited a distinctively high onset potential different from that of the bulky oxide particles.

  8. X-ray Fluorescence Tomography of Aged Fluid-Catalytic-Cracking Catalyst Particles Reveals Insight into Metal Deposition Processes

    NARCIS (Netherlands)

    Kalirai, Samanbir; Boesenberg, Ulrike; Falkenberg, Gerald; Meirer, Florian; Weckhuysen, Bert M.|info:eu-repo/dai/nl/285484397

    2015-01-01

    Microprobe X-ray fluorescence tomography was used to investigate metal poison deposition in individual, intact and industrially deactivated fluid catalytic cracking (FCC) particles at two differing catalytic life-stages. 3D multi-element imaging, at submicron resolution was achieved by using a

  9. Single-Molecule Fluorescence Microscopy Reveals Local Diffusion Coefficients in the Pore Network of an Individual Catalyst Particle

    NARCIS (Netherlands)

    Hendriks, Frank|info:eu-repo/dai/nl/412642697; Meirer, Florian; Kubarev, Alexey V.; Ristanovic, Zoran|info:eu-repo/dai/nl/328233005; Roeffaers, Maarten B J; Vogt, Eelco T. C.|info:eu-repo/dai/nl/073717398; Bruijnincx, Pieter C. A.|info:eu-repo/dai/nl/33799529X; Weckhuysen, Bert M.|info:eu-repo/dai/nl/285484397

    2017-01-01

    We used single-molecule fluorescence microscopy to study self-diffusion of a feedstock-like probe molecule with nanometer accuracy in the macropores of a micrometer-sized, real-life fluid catalytic cracking (FCC) particle. Movies of single fluorescent molecules allowed their movement through the

  10. Thermal residual stresses in SiC particle reinforced aluminium composites: a study by the Taylor-based nonlocal theory of plasticity

    Science.gov (United States)

    Cao, D. F.; Liu, X.; Mei, H.; Lei, Z. T.; Liu, L. S.

    2013-03-01

    Strain gradient theories have been considered to be an effective means for capturing the size effects on ceramic particle-reinforced metal-matrix composites (MMCp), but the results predicted by them are significantly lower than the corresponding experimental data. One reason might be, that the thermal residual stresses caused by thermal contraction mismatch between the metal matrix and the ceramic particle were neglected in the numerical models. By incorporating the Taylor-based nonlocal theory (TNT) of plasticity, the finite element method (FEM) is applied in the present research, to investigate the effect of thermal residual stresses on the yield stress and average axial stresses of the aluminium matrix reinforced by silicon carbide particles (SiCp/Al). The elements of the matrix have been implemented in the ABAQUS finite element code through its USER-ELEMENT (UEL) interface for TNT plasticity. Some comparisons with the associated literature demonstrate that the numerical model with the thermal residual stresses is more in agreement with the experimental results.

  11. Large zeolite H-ZSM-5 crystals as models for the methanol-to-hydrocarbons process: bridging the gap between single-particle examination and bulk catalyst analysis.

    Science.gov (United States)

    Hofmann, Jan P; Mores, Davide; Aramburo, Luis R; Teketel, Shewangizaw; Rohnke, Marcus; Janek, Jürgen; Olsbye, Unni; Weckhuysen, Bert M

    2013-06-24

    The catalytic, deactivation, and regeneration characteristics of large coffin-shaped H-ZSM-5 crystals were investigated during the methanol-to-hydrocarbons (MTH) reaction at 350 and 500 °C. Online gas-phase effluent analysis and examination of retained material thereof were used to explore the bulk properties of large coffin-shaped zeolite H-ZSM-5 crystals in a fixed-bed reactor to introduce them as model catalysts for the MTH reaction. These findings were related to observations made at the individual particle level by using polarization-dependent UV-visible microspectroscopy and mass spectrometric techniques after reaction in an in situ microspectroscopy reaction cell. Excellent agreement between the spectroscopic measurements and the analysis of hydrocarbon deposits by means of retained hydrocarbon analysis and time-of-flight secondary-ion mass spectrometry of spent catalyst materials was observed. The obtained data reveal a shift towards more condensed coke deposits on the outer zeolite surface at higher reaction temperatures. Zeolites in the fixed-bed reactor setup underwent more coke deposition than those reacted in the in situ microspectroscopy reaction cell. Regeneration studies of the large zeolite crystals were performed by oxidation in O2 /inert gas mixtures at 550 °C. UV-visible microspectroscopic measurements using the oligomerization of styrene derivatives as probe reaction indicated that the fraction of strong acid sites decreased during regeneration. This change was accompanied by a slight decrease in the initial conversion obtained after regeneration. H-ZSM-5 deactivated more rapidly at higher reaction temperature. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Novel sample preparation for operando TEM of catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Benjamin K.; Barker, Trevor M. [School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ 85287-6106 (United States); Crozier, Peter A., E-mail: crozier@asu.edu [School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ 85287-6106 (United States)

    2015-09-15

    A new TEM sample preparation method is developed to facilitate operando TEM of gas phase catalysis. A porous Pyrex-fiber pellet TEM sample was produced, allowing a comparatively large amount of catalyst to be loaded into a standard Gatan furnace-type tantalum heating holder. The increased amount of catalyst present inside the environmental TEM allows quantitative determination of the gas phase products of a catalytic reaction performed in-situ at elevated temperatures. The product gas concentration was monitored using both electron energy loss spectroscopy (EELS) and residual gas analysis (RGA). Imaging of catalyst particles dispersed over the pellet at atomic resolution is challenging, due to charging of the insulating glass fibers. To overcome this limitation, a metal grid is placed into the holder in addition to the pellet, allowing catalyst particles dispersed over the grid to be imaged, while particles in the pellet, which are assumed to experience identical conditions, contribute to the overall catalytic conversion inside the environmental TEM cell. The gas within the cell is determined to be well-mixed, making this assumption reasonable. - Highlights: • High in-situ conversion of CO to CO{sub 2} achieved by a novel TEM sample preparation method. • A 3 mm fiber pellet increases the TEM sample surface area by 50×. • Operando atomic resolution is maintained by also including a 3 mm grid in the sample. • Evidence for a well-mixed gas composition inside the ETEM cell is given.

  13. Novel sample preparation for operando TEM of catalysts.

    Science.gov (United States)

    Miller, Benjamin K; Barker, Trevor M; Crozier, Peter A

    2015-09-01

    A new TEM sample preparation method is developed to facilitate operando TEM of gas phase catalysis. A porous Pyrex-fiber pellet TEM sample was produced, allowing a comparatively large amount of catalyst to be loaded into a standard Gatan furnace-type tantalum heating holder. The increased amount of catalyst present inside the environmental TEM allows quantitative determination of the gas phase products of a catalytic reaction performed in-situ at elevated temperatures. The product gas concentration was monitored using both electron energy loss spectroscopy (EELS) and residual gas analysis (RGA). Imaging of catalyst particles dispersed over the pellet at atomic resolution is challenging, due to charging of the insulating glass fibers. To overcome this limitation, a metal grid is placed into the holder in addition to the pellet, allowing catalyst particles dispersed over the grid to be imaged, while particles in the pellet, which are assumed to experience identical conditions, contribute to the overall catalytic conversion inside the environmental TEM cell. The gas within the cell is determined to be well-mixed, making this assumption reasonable. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Chemical imaging of catalyst deactivation during the conversion of renewables at the single particle level: etherification of biomass-based polyols with alkenes over H-Beta zeolites.

    Science.gov (United States)

    Parvulescu, Andrei N; Mores, Davide; Stavitski, Eli; Teodorescu, Cristian M; Bruijnincx, Pieter C A; Gebbink, Robertus J M Klein; Weckhuysen, Bert M

    2010-08-04

    The etherification of biomass-based alcohols with various linear alpha-olefins under solvent-free conditions was followed in a space- and time-resolved manner on 9 microm large H-Beta zeolite crystals by confocal fluorescence microscopy. This allowed us to visualize the interaction with the substrate and distribution of the coke products into the catalyst at the level of an individual zeolite crystal during the etherification process. The spectroscopic information obtained on the micrometer-scale zeolite was in line with the results obtained with bulk characterization techniques and further confirmed by the catalytic results obtained both for micrometer-scale and nanoscale zeolites. This allowed us to explain the influence of the substrate type (glycerol, glycols, and alkenes) and zeolite properties (Si/Al ratio and particle size) on the etherification activity. The etherification of the biomass-based alcohols takes place mainly on the external surface of the zeolite particles. The gradual blockage of the external surface of the zeolite results in a partial or total loss of etherification activity. The deactivation could be attributed to olefin oligomerization. The high conversions obtained in the etherification of 1,2-propylene glycol with long linear alkenes (up to 80%) and the pronounced deactivation of the zeolite observed in the etherification of glycerol with long linear alkenes (max. 20% conversion) were explained by the spectroscopic measurements and is due to differences in the adsorption, i.e., in the center of the zeolite particle for glycerol and on the external surface in the case of glycols.

  15. Surface areas of turbostratic graphitic carbons prepared from a resin using nickel particles, 20 nm, as graphitization catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Oya, A.; Inoue, E.; Otani, S.; Marsh, H.

    1981-11-01

    Nickel particles were used to graphitize catalytically a non-graphitizing carbon to create a turbostratic graphitic material called the T/SUB/s-component. This method was examined by X-ray diffraction. Coals on heat treatment to temperatures >1270 K form T/SUB/s-component carbons. Therefore, considerations of the properties of the T/SUB/s-component carbon may have relevance to considerations of the operational performances of blast furnace coke. (22 refs.)

  16. Covalent immobilization of α-amylase on magnetic particles as catalyst for hydrolysis of high-amylose starch.

    Science.gov (United States)

    Guo, Hui; Tang, Yi; Yu, Yang; Xue, Lu; Qian, Jun-Qing

    2016-06-01

    Enzyme immobilized on magnetic particles can be used as efficient recoverable biocatalysts under strong magnetic response. To enable re-use of enzyme, modified Fe3O4 particles were used as carrier to immobilize α-amylase in this paper. Firstly, the surface of Fe3O4 particles were coated with amino groups by direct using TEOS (tetraethoxysilane) followed by treatment with APTES (3-aminopropyltriethoxysilane) and then carboxylated by reacting it with succinic anhydride. In addition, the effect of the immobilization condition on enzyme activity recovery and immobilization efficiency were investigated. The results showed that the optimal immobilization occurred under following conditions: pH 5.5, 40°C, enzyme concentration of 20mgmL(-1), reaction time for 36h. Using immobilized α-amylase as biocatalyst, the optimum pH and temperature for hydrolysis were observed to be 6.5 and 60°C. The kinetics of hydrolysis reaction were studied using Michaelis-Menten equation. The affinity constant (Km) and maximum reaction rate (vmax) of magnetic particles immobilization α-amylase (MPIA) was 0.543mgmL(-1) and 1.321mgmin(-1) compared to those of 0.377mgmL(-1) and 6.859mgmin(-1) of free enzyme. After immobilization, enzymatic activity, storage stability, thermo-stability, and reusability of MPIA were found superior to those of the free one. MPIA maintained 86% enzyme activity after 30 days and maintained 78% enzyme activity after recycling six times. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. A simple method for detection of gunshot residue particles from hands, hair, face, and clothing using scanning electron microscopy/wavelength dispersive X-ray (SEM/WDX).

    Science.gov (United States)

    Kage, S; Kudo, K; Kaizoji, A; Ryumoto, J; Ikeda, H; Ikeda, N

    2001-07-01

    We devised a simple and rapid method for detection of gunshot residue (GSR) particles, using scanning electron microscopy/wavelength dispersive X-ray (SEM/WDX) analysis. Experiments were done on samples containing GSR particles obtained from hands, hair, face, and clothing, using double-sided adhesive coated aluminum stubs (tape-lift method). SEM/WDX analyses for GSR were carried out in three steps: the first step was map analysis for barium (Ba) to search for GSR particles from lead styphnate primed ammunition, or tin (Sn) to search for GSR particles from mercury fulminate primed ammunition. The second step was determination of the location of GSR particles by X-ray imaging of Ba or Sn at a magnification of x 1000-2000 in the SEM, using data of map analysis, and the third step was identification of GSR particles, using WDX spectrometers. Analysis of samples from each primer of a stub took about 3 h. Practical applications were shown for utility of this method.

  18. Catalysts for low temperature oxidation

    Science.gov (United States)

    Toops, Todd J.; Parks, III, James E.; Bauer, John C.

    2016-03-01

    The invention provides a composite catalyst containing a first component and a second component. The first component contains nanosized gold particles. The second component contains nanosized platinum group metals. The composite catalyst is useful for catalyzing the oxidation of carbon monoxide, hydrocarbons, oxides of nitrogen, and other pollutants at low temperatures.

  19. Oxidation of carbon by CeO{sub 2}: Effect of the contact between carbon and catalyst particles

    Energy Technology Data Exchange (ETDEWEB)

    May Issa; Corinne Petit; Alain Brillard; Jean-Francois Brilhac [Universite de Haute-Alsace, Mulhouse (France). Laboratoire Gestion des Risques et Environnement

    2008-05-15

    The oxidation of carbon black, CB, in presence of CeO{sub 2} is investigated to gain a better understanding of the effect of the contact between the two solids during this reaction. Different CB/CeO{sub 2} mixtures are tested in a fixed bed reactor. The experimental data are used to propose a model for CB oxidation in presence of CeO{sub 2}. It accounts for the size distribution of CeO{sub 2} particles, the contact area between CB and CeO{sub 2}, the mass of CB in the sample and the initial ratio CB/CeO{sub 2}. Corresponding kinetic parameters are determined. 35 refs., 10 figs., 3 tabs.

  20. Dispersed catalysts for transforming extra heavy crude oil into transportable upgraded crude: phase identification

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, S.; Canizales, E.; Machin, I. [Gerencia Depttal de Investigacion Estrategica en Refinacion PDVSA Intevep (Venezuela); Segovia, X.; Rivas, A.; Lopez, E.; Pena, J.P.; Rojas, J.D.; Sardella, R. [Gerencia Depttal de Infraestructura y Mejoramiento en Faja Petrolifera PDVSA Intevep (Venezuela)

    2011-07-01

    A new technology to convert extra heavy crude oil into transportable upgraded crude has been developed. A water/oil emulsion composed of steam and catalyst precursors is introduced in the feed which then generates unsupported dispersed catalyst in situ under thermal decomposition. The aim of this paper is to characterize the particles. The study was conducted in a laboratory and on a pilot scale on three different vacuum residues using high resolution transmission electron microscopy and a transmission electron microscope. Results showed that the particles were formed by oxides and inorganic sulphur based in transition metals and their sizes ranged between 5 and 120 nm; in addition, good dispersion was observed. This study demonstrated that the process involved in the generation of dispersed catalyst is extremely complex and showed that further work with heavy crude oils and its residua is required to understand the mechanisms involved.

  1. Structure of silica-supported catalysts

    International Nuclear Information System (INIS)

    Gladden, L.F.; Vignaux, M.; Griffiths, R.W.; Jackson, S.D.; Jones, J.R.; Sharratt, A.P.; Robertson, F.J.; Webb, G.

    1992-01-01

    Neutron diffraction and SANS studies of silica supported metal catalysts have indicated that more active metal:silica catalysts are produced when the silica support has a relatively high content of three-membered rings in its network structure. SANS studies also suggest that the more active catalysts possess a bimodal metal particle size distribution. (orig.)

  2. Uncovering the local inelastic interactions during manufacture of ductile cast iron: How the substructure of the graphite particles can induce residual stress concentrations in the matrix

    DEFF Research Database (Denmark)

    Andriollo, Tito; Hellström, Kristina; Sonne, Mads Rostgaard

    2018-01-01

    Recent X-ray diffraction (XRD) measurements have revealed that plastic deformation and a residual elastic strain field can be present around the graphite particles in ductile cast iron after manufacturing, probably due to some local mismatch in thermal contraction. However, as only one component...... of the elastic strain tensor could be obtained from the XRD data, the shape and magnitude of the associated residual stress field have remained unknown. To compensate for this and to provide theoretical insight into this unexplored topic, a combined experimental-numerical approach is presented in this paper....... First, a ma terial equivalent to the ductile cast iron matrix is manufactured and subjected to dilato- metric and high-temperature tensile tests. Subsequently, a two-scale hierarchical top-down model is devised, calibrated on the basis of the collected data and used to simulate the interaction between...

  3. Uncovering the local inelastic interactions during manufacture of ductile cast iron: How the substructure of the graphite particles can induce residual stress concentrations in the matrix

    Science.gov (United States)

    Andriollo, Tito; Hellström, Kristina; Sonne, Mads Rostgaard; Thorborg, Jesper; Tiedje, Niels; Hattel, Jesper

    2018-02-01

    Recent X-ray diffraction (XRD) measurements have revealed that plastic deformation and a residual elastic strain field can be present around the graphite particles in ductile cast iron after manufacturing, probably due to some local mismatch in thermal contraction. However, as only one component of the elastic strain tensor could be obtained from the XRD data, the shape and magnitude of the associated residual stress field have remained unknown. To compensate for this and to provide theoretical insight into this unexplored topic, a combined experimental-numerical approach is presented in this paper. First, a material equivalent to the ductile cast iron matrix is manufactured and subjected to dilatometric and high-temperature tensile tests. Subsequently, a two-scale hierarchical top-down model is devised, calibrated on the basis of the collected data and used to simulate the interaction between the graphite particles and the matrix during manufacturing of the industrial part considered in the XRD study. The model indicates that, besides the viscoplastic deformation of the matrix, the effect of the inelastic deformation of the graphite has to be considered to explain the magnitude of the XRD strain. Moreover, the model shows that the large elastic strain perturbations recorded with XRD close to the graphite-matrix interface are not artifacts due to e.g. sharp gradients in chemical composition, but correspond to residual stress concentrations induced by the conical sectors forming the internal structure of the graphite particles. In contrast to common belief, these results thus suggest that ductile cast iron parts cannot be considered, in general, as stress-free at the microstructural scale.

  4. COMPARISON OF PARTICLE SIZE DISTRIBUTIONS AND ELEMENTAL PARTITIONING FROM THE COMBUSTION OF PULVERIZED COAL AND RESIDUAL FUEL OIL

    Science.gov (United States)

    The paper gives results of experimental efforts in which three coals and a residual fuel oil were combusted in three different systems simulating process and utility boilers. Particloe size distributions (PSDs) were determined using atmospheric and low-pressure impaction, electr...

  5. Bio-oil hydrodeoxygenation catalysts produced using strong electrostatic adsorption

    Science.gov (United States)

    We synthesized hydrothermally stable metal catalysts with controlled particle size and distribution, with the goal of determining which catalyst(s) can selectively catalyze the production of aromatics from bio-oil (from pyrolysis of biomass). Both precious and base transition metal catalysts (Ru, Pt...

  6. Analysis of the spallation residues and the associated particles in the reaction Fe+p at 1 GeV per nucleon

    International Nuclear Information System (INIS)

    Le Gentil, E.

    2006-09-01

    SPALADIN is a new type of spallation experiment that has been carried out at the GSI accelerator facility (Germany) in order to improve the modelling of the spallation reaction. This experiment is based on the coincidence measurement in inverse kinematics of the spallation residues and the de-excitation fragments. This work presents the analysis of Fe 56 + p reaction at 1 GeV per nucleon. Results on cross-sections and heavy residue velocity spectra are compared to previous data and enabled us to characterize the setup. Most of the element production cross-sections have been obtained with an uncertainty below 10 per cent. In the particular case of helium, its production cross-section has been measured to be σ(1 GeV) = (598 ± 67) mb. The knowledge of this cross-section is important to assess the irradiation damage undergone by the window separating the accelerator from the target. The study of the de-excitation of the pre-fragment shows that the evaporation of light particles (Z ≤ 2) is the main way of de-excitation whatever the collision centrality. However, the de-excitation through the emission of intermediate mass fragments is observed in 5% of the events and most of these events correspond to a very asymmetric binary breaking. The velocity distributions of light residues (with regards to the mass of the projectile) show a significant disagreement with the average velocities predicted by spallation codes. (A.C.)

  7. Distribution of aged 14C-PCB and 14C-PAH residues in particle-size and humic fractions of an agricultural soil.

    Science.gov (United States)

    Doick, Kieron J; Burauel, Peter; Jones, Kevin C; Semple, Kirk T

    2005-09-01

    Organic matter is considered to be the single most importantfactor limiting availability and mobility of persistent organic pollutants (POPs) in soil. This study aimed to characterize the distribution of 14C-PCB (congeners 28 and 52) and 14C-PAH (fluoranthene and benzo[a]pyrene) residues in an Orthic Luvisol soil obtained from two lysimeter studies initiated in 1990 at the Agrosphere Institute (Forschungszentrum Jülich GmbH, Germany). The lysimeter soils contained a low-density OM fraction, isolated during soil washing, which contained a significant fraction (3-12%) of the total 14C-activity. Soils were also fractionated according to three particle sizes: >20, 20-2, and (20 microm) for the PCBs. Relative affinity values of 14C-activity for the different particle sizes varied in the order 20-2 microm > ( (>20 microm) for the PAHs. The distribution of 14C-PCB or 14C-PAH residues in the organic and inorganic matrixes of the particle-size fractions was determined using methyl isobutyl ketone (MIBK). 14C-PCB and 14C-PAH-associated activities were primarily located in the humin fraction of the 20-2 and soil. A small fraction was associated with the fulvic and humic acid fractions; these were quantitatively more important for the PAHs than the PCBs. There appeared to be a high degree of association of 14C-activity with the mineral fraction following MIBK separation of the humic fractions, ranging between 8 and 52% for 14C-PCBs and 57-80% for 14C-PAHs. The mineral (inorganic) component of the soils apparently played a significant (previously unreported) role in the sequestration of both PCBs 28 and 52 and the PAHs fluoranthene and benzo[a]pyrene.

  8. A highly efficient nano-Fe{sub 3}O{sub 4} encapsulated-silica particles bearing sulfonic acid groups as a solid acid catalyst for synthesis of 1,8-dioxo-octahydroxanthene derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Naeimi, Hossein, E-mail: naeimi@kashanu.ac.ir; Nazifi, Zahra Sadat [University of Kashan, Department of Organic Chemistry, Faculty of Chemistry (Iran, Islamic Republic of)

    2013-11-15

    The functionalization of silica-coated Fe{sub 3}O{sub 4} magnetic nanoparticles (Fe{sub 3}O{sub 4}@SiO{sub 2}) using chlorosulfonic acid were afforded sulfonic acid-functionalized magnetic Fe{sub 3}O{sub 4} nanoparticles (Fe{sub 3}O{sub 4}@SiO{sub 2}–SO{sub 3}H) that can be applied as an organic–inorganic hybrid heterogeneous catalyst. The used Fe{sub 3}O{sub 4} magnetic nanoparticles are 18–30 nm sized that was rapidly functionalized and can be used as catalyst in organic synthesis. The prepared nanoparticles were characterized by X-ray diffraction analysis, magnetization curve, scanning electron microscope, dynamic laser scattering, and FT-IR measurements. The resulting immobilized catalysts have been successfully used in the synthesis of 1,8‐dioxo-octahydroxanthene derivatives under solvent free condition. This procedure has many advantages such as; a much milder method, a shorter reaction time, a wide range of functional group tolerance, and absence of any tedious workup or purification. Other remarkable features include the catalyst can be reused at least five times without any obvious change in its catalytic activity. This procedure also avoids hazardous reagents/solvents, and thus can be an eco-friendly alternative to the existing methods.Graphical AbstractA highly efficient nano-Fe{sub 3}O{sub 4} encapsulated-silica particles bearing sulfonic acid groups as a solid acid catalyst for synthesis of 1,8-dioxo-octahydroxanthene derivatives.

  9. Probabilistic evidential assessment of gunshot residue particle evidence (Part I): likelihood ratio calculation and case pre-assessment using Bayesian networks.

    Science.gov (United States)

    Biedermann, A; Bozza, S; Taroni, F

    2009-10-30

    Well developed experimental procedures currently exist for retrieving and analyzing particle evidence from hands of individuals suspected of being associated with the discharge of a firearm. Although analytical approaches (e.g. automated Scanning Electron Microscopy with Energy Dispersive X-ray (SEM-EDS) microanalysis) allow the determination of the presence of elements typically found in gunshot residue (GSR) particles, such analyses provide no information about a given particle's actual source. Possible origins for which scientists may need to account for are a primary exposure to the discharge of a firearm or a secondary transfer due to a contaminated environment. In order to approach such sources of uncertainty in the context of evidential assessment, this paper studies the construction and practical implementation of graphical probability models (i.e. Bayesian networks). These can assist forensic scientists in making the issue tractable within a probabilistic perspective. The proposed models focus on likelihood ratio calculations at various levels of detail as well as case pre-assessment.

  10. Synthesis of PtSn nanostructured catalysts supported over TiO{sub 2} and Ce-doped TiO{sub 2} particles for the electro-oxidation of ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, A.E. [Instituto de Ingeniería Electroquímica y Corrosión (INIEC), CONICET, Universidad Nacional del Sur. Av. Alem 1253, Bahía Blanca B8000CPB (Argentina); Gravina, A.N. [Departamento de Química, INQUISUR, CONICET, Universidad Nacional del Sur, Av. Alem 1253, Bahía Blanca B8000CPB (Argentina); Sieben, J.M., E-mail: jmsieben@uns.edu.ar [Instituto de Ingeniería Electroquímica y Corrosión (INIEC), CONICET, Universidad Nacional del Sur. Av. Alem 1253, Bahía Blanca B8000CPB (Argentina); Messina, P.V. [Departamento de Química, INQUISUR, CONICET, Universidad Nacional del Sur, Av. Alem 1253, Bahía Blanca B8000CPB (Argentina); Duarte, M.M.E. [Instituto de Ingeniería Electroquímica y Corrosión (INIEC), CONICET, Universidad Nacional del Sur. Av. Alem 1253, Bahía Blanca B8000CPB (Argentina)

    2016-09-15

    Highlights: • PtSn particles supported on TiO2 and Ce-doped TiO2 were evaluated as catalysts for EOR. • PtSn/TiO2 showed better mass current and higher TON than PtSn/Ce–TiO2 materials. • The activity for EOR decreased markedly with increasing Ce content in the TiO2. - Abstract: PtSn/TiO2 and PtSn/Ce-doped TiO2 catalysts were synthesized and evaluated for ethanol electro-oxidation in acid media. Titanium dioxide and Ce-doped TiO2 nanoparticles were prepared by hydrothermal method followed by calcination at 923 K. Bimetallic PtSn catalysts supported on the oxide materials were synthesized by microwave assisted reduction in ethylene glycol (EG). The structural properties of the resulting materials were evaluated via TEM and XRD, and the compositions were assessed by EDX and ICP-AES analysis. PtSn nanoparticles of about 3–4 nm were deposited on TiO2 and Ce–TiO2 particles. It was found that the catalyst composition is scarcely influenced by the cerium content in the mixed oxides while the electrochemical surface area per unit mass decreases upon the incorporation of Ce in the anatase lattice. The electrochemical tests pointed out that the electrocatalytic activity for ethanol oxidation decreases markedly as the Ce content increases. The results indicate that the presence of cerium in the titanium dioxide crystalline network induces local structural and electronic modifications, thereby leading to a reduction of the crystallinity, surface conductivity and the amount of OH species adsorbed on the surface of the oxide support.

  11. Herpes Simplex Virus Type 1 Glycoprotein B Requires a Cysteine Residue at Position 633 for Folding, Processing, and Incorporation into Mature Infectious Virus Particles

    Science.gov (United States)

    Laquerre, Sylvie; Anderson, Dina B.; Argnani, Rafaela; Glorioso, Joseph C.

    1998-01-01

    Herpes simplex virus type 1 (HSV-1) glycoprotein B (gB) resides in the virus envelope in an oligomeric form and plays an essential role in virus entry into susceptible host cells. The oligomerizing domain is a movable element consisting of amino acids 626 to 653 in the gB external domain. This domain contains a single cysteine residue at position 633 (Cys-633) that is predicted to form an intramolecular disulfide bridge with Cys-596. In this study, we examined gB oligomerization, processing, and incorporation into mature virus during infection by two mutant viruses in which either the gB Cys-633 [KgB(C633S)] or both Cys-633 and Cys-596 [KgB(C596S/C633S)] residues were mutated to serine. The result of immunofluorescence studies and analyses of released virus particles showed that the mutant gB molecules were not transported to the cell surface or incorporated into mature virus envelopes and thus infectious virus was not produced. Immunoprecipitation studies revealed that the mutant gB molecules were in an oligomeric configuration and that these mutants produced hetero-oligomers with a truncated form of gB consisting of residues 1 to 43 and 595 to 904, the latter containing the oligomerization domain. Pulse-chase experiments in combination with endoglycosidase H treatment determined that the mutant molecules were improperly processed, having been retained in the endoplasmic reticulum (ER). Coimmunoprecipitation experiments revealed that the cysteine mutations resulted in gB misfolding and retention by the molecular chaperones calnexin, calreticulin, and Grp78 in the ER. The altered conformation of the gB mutant glycoproteins was directly detected by a reduction in monoclonal antibody recognition of two previously defined distinct antigenic sites located within residues 381 to 441 and 595 to 737. The misfolded molecules were not transported to the cell surface as hetero-oligomers with wild-type gB, suggesting that the conformational change could not be corrected by

  12. Finding Interstellar Particle Impacts on Stardust Aluminium Foils: The Safe Handling, Imaging, and Analysis of Samples Containing Femtogram Residues

    Science.gov (United States)

    Kearsley, A. T.; Westphal, A. J.; Stadermann, F. J.; Armes, S. P.; Ball, A. D.; Borg, J.; Bridges, J. C.; Brownlee, D. E.; Burchell, M. J.; Chater, R. J.; hide

    2010-01-01

    Impact ionisation detectors on a suite of spacecraft have shown the direction, velocity, flux and mass distribution of smaller ISP entering the Solar System. During the aphelion segments of the Stardust flight, a dedicated collector surface was oriented to intercept ISP of beta = 1, and returned to Earth in January 2006. In this paper we describe the probable appeareance and size of IS particle craters from initial results of experimental impacts and numerical simulation, explain how foils are being prepared and mounted for crater searching by automated acquisition of high magnification electron images (whilst avoiding contamination of the foils) and comment on appropriate analytical techniques for Preliminary Examination (PE).

  13. Uses of extraction and ion exchange chromatography in the thorium and rare earths separation from industrial residue generated in thorium purification unity at IPEN. Application of rare earths as catalysts for generation of hydrogen

    International Nuclear Information System (INIS)

    Zini, Josiane

    2010-01-01

    In the 70's a pilot plant for studies of different concentrates processing obtained from the chemical processing of monazite was operated at IPEN / CNEN-SP, with a view to obtaining thorium of nuclear purity. This unity was operated on an industrial scale since 1985, generating around 25 metric tons of residue and was closed in 2002. This waste containing thorium and rare earths was named Retoter (Rejeito de Torio e Terras Raras, in portuguese) and stored in the IPEN Safeguards shed. This paper studies the treatment of the waste, aimed at environmental, radiological and technology. Were studied two cases for the chromatographic separation of thorium from rare earths. One of them was the chromatographic extraction, where the extracting agent tributyl phosphate was supported on polymeric resins Amberlite XAD16. The other method is studied for comparison purposes, since the material used in chromatographic extraction is unprecedented with regard to the separation of thorium, was the ion-exchange chromatography using DOWEX 1-X8 strong cationic resin. Was studied also the chromatographic process of extraction with the extracting agent DEHPA supported on Amberlite XAD16 for the fractionation in groups of rare earths elements. Thorium was separated with high purity for strategic purposes and rare earths recovered free from thorium, were tested as a catalyst for ethanol reforming to hydrogen obtaining which is used in fuel cells for power generation. (author)

  14. Composition of carbonization residues

    Energy Technology Data Exchange (ETDEWEB)

    Hupfer; Leonhardt

    1943-11-30

    This report gave a record of the composition of several samples of residues from carbonization of various hydrogenation residue from processing some type of coal or tar in the Bergius process. These included Silesian bituminous coal processed at 600 atm. with iron catalyst, in one case to produce gasoline and middle oil and in another case to produce heavy oil excess, Scholven coal processed at 250 atm. with tin oxalate and chlorine catalyst, Bruex tar processed in a 10-liter oven using iron catalyst, and a pitch mixture from Welheim processed in a 10-liter over using iron catalyst. The values gathered were compared with a few corresponding values estimated for Boehlen tar and Gelsenberg coal based on several assumptions outlined in the report. The data recorded included percentage of ash in the dry residue and percentage of carbon, hydrogen, oxygen, nitrogen, chlorine, total sulfur, and volatile sulfur. The percentage of ash varied from 21.43% in the case of Bruex tar to 53.15% in the case of one of the Silesian coals. Percentage of carbon varied from 44.0% in the case of Scholven coal to 78.03% in the case of Bruex tar. Percentage of total sulfur varied from 2.28% for Bruex tar to a recorded 5.65% for one of the Silesian coals and an estimated 6% for Boehlen tar. 1 table.

  15. Catalysts preparing

    International Nuclear Information System (INIS)

    Normatov, I.Sh.; Mirsaidov, U.M.

    2003-01-01

    One of the base area of zeolites industry using is catalysis. The catalytic properties of zeolites use in the carbonated reactions in the petrochemistry. Last years zeolite catalysts use in oxidative-reduction processes

  16. Lunar CATALYST

    Data.gov (United States)

    National Aeronautics and Space Administration — Lunar Cargo Transportation and Landing by Soft Touchdown (Lunar CATALYST) is a NASA initiative to encourage the development of U.S. private-sector robotic lunar...

  17. Photo-oxidation catalysts

    Science.gov (United States)

    Pitts, J Roland [Lakewood, CO; Liu, Ping [Irvine, CA; Smith, R Davis [Golden, CO

    2009-07-14

    Photo-oxidation catalysts and methods for cleaning a metal-based catalyst are disclosed. An exemplary catalyst system implementing a photo-oxidation catalyst may comprise a metal-based catalyst, and a photo-oxidation catalyst for cleaning the metal-based catalyst in the presence of light. The exposure to light enables the photo-oxidation catalyst to substantially oxidize absorbed contaminants and reduce accumulation of the contaminants on the metal-based catalyst. Applications are also disclosed.

  18. La préparation des catalyseurs. Première partie : Germination et croissance des particules. Importance de la sursaturation du milieu Preparation of Catalysts. Part One: Particle Germination and Growth. Importance of the Supersaturation of the Medium

    Directory of Open Access Journals (Sweden)

    Marcilly C.

    2006-11-01

    Full Text Available Cet article présente les deux notions fondamentales et générales de germination et croissance des particules ou cristaux élémentaires qui peuvent former aussi bien le support du catalyseur que l'agent actif dispersé à sa surface. Germination et croissance sont deux étapes très importantes qui interviennent à divers stades de la préparation des catalyseurs : précipitation, séchage, calcination, etc. On montre que le paramètre essentiel qui régit ces deux étapes et qui détermine la dimension, la structure et le faciès des particules élémentaires est la sursaturation du milieu. This article describes the two fundamental and general concepts of germination and growth of elementary particles or crystals which may form either the catalyst support or the dispersed active agent on its surface. Germination and growth are two very important steps which occur at dif-ferent stages of the preparation of catalysts, i,e. precipitation, drying, calcination, etc. The supersaturation of the medium is shown to be the essential parameter governing these two steps and determining the size, structure and facies of elementary particles.

  19. Novel Sol-Gel Based Pt Nanocluster Catalysts for Propane Dehydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Boespflug, Elaine; Kawola, Jeffrey S.; Martino, Anthony; Sault, Allen G.

    1999-08-09

    We report propane dehydrogenation behavior of catalysts prepared using two novel synthesis strategies that combine inverse micelle Pt nanocluster technology with silica and alumina sol-gel processing. Unlike some other sol-gel catalyst preparations. Pt particles in these catalysts are not encapsulated in the support structure and the entire Pt particle surface is accessible for reaction. Turnover frequencies (TOF) for these catalysts are comparable to those obtained over Pt catalysts prepared by traditional techniques such as impregnation, yet the resistance to deactivation by carbon poisoning is much greater in our catalysts. The deactivation behavior is more typical of traditionally prepared PtSn catalysts than of pure Pt catalysts.

  20. Particle shape optimization by changing from an isotropic to an anisotropic nanostructure: preparation of highly active and stable supported Pt catalysts in microemulsions

    Science.gov (United States)

    Parapat, Riny Y.; Wijaya, Muliany; Schwarze, Michael; Selve, Sören; Willinger, Marc; Schomäcker, Reinhard

    2012-12-01

    We recently introduced a new method to synthesize an active and stable Pt catalyst, namely thermo-destabilization of microemulsions (see R. Y. Parapat, V. Parwoto, M. Schwarze, B. Zhang, D. S. Su and R. Schomäcker, J. Mater. Chem., 2012, 22 (23), 11605-11614). We are able to produce Pt nanocrystals with a small size (2.5 nm) of an isotropic structure i.e. truncated octahedral and deposit them well on support materials. Although we have obtained good results, the performance of the catalyst still needed to be improved and optimized. We followed the strategy to retain the small size but change the shape to an anisotropic structure of Pt nanocrystals which produces more active sites by means of a weaker reducing agent. We found that our catalysts are more active than those we reported before and even show the potential to be applied in a challenging reaction such as hydrogenation of levulinic acid.We recently introduced a new method to synthesize an active and stable Pt catalyst, namely thermo-destabilization of microemulsions (see R. Y. Parapat, V. Parwoto, M. Schwarze, B. Zhang, D. S. Su and R. Schomäcker, J. Mater. Chem., 2012, 22 (23), 11605-11614). We are able to produce Pt nanocrystals with a small size (2.5 nm) of an isotropic structure i.e. truncated octahedral and deposit them well on support materials. Although we have obtained good results, the performance of the catalyst still needed to be improved and optimized. We followed the strategy to retain the small size but change the shape to an anisotropic structure of Pt nanocrystals which produces more active sites by means of a weaker reducing agent. We found that our catalysts are more active than those we reported before and even show the potential to be applied in a challenging reaction such as hydrogenation of levulinic acid. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr32122j

  1. Behaviour of six sulphided iron hydroliquefaction catalysts

    International Nuclear Information System (INIS)

    Cook, P.S.; Cashion, J.D.; Bell, A.P.

    1994-01-01

    Five iron ore samples and a synthetic magnetite were added to Wandoan bituminous coal as hydroliquefaction catalysts. Catalyst transformations after sulphiding and after subsequent hydrogenation were analysed. The conversion efficiency increased with decreasing particle size or increased crystallographic disorder and showed that different catalytic mechanisms operate in the hydroliquefaction of brown and black coals. (orig.)

  2. Highly dispersed metal catalyst

    Science.gov (United States)

    Xiao, Xin; West, William L.; Rhodes, William D.

    2016-11-08

    A supported catalyst having an atomic level single atom structure is provided such that substantially all the catalyst is available for catalytic function. A process of forming a single atom catalyst unto a porous catalyst support is also provided.

  3. A novel continuous process for synthesis of carbon nanotubes using iron floating catalyst and MgO particles for CVD of methane in a fluidized bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Maghsoodi, Sarah; Khodadadi, Abasali [Catalysis and Nanostructured Materials Research Laboratory, School of Chemical Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Mortazavi, Yadollah, E-mail: mortazav@ut.ac.ir [Nanoelectronics Centre of Excellence, University of Tehran, POB 11365-4563, Tehran (Iran, Islamic Republic of)

    2010-02-15

    A novel continuous process is used for production of carbon nanotubes (CNTs) by catalytic chemical vapor deposition (CVD) of methane on iron floating catalyst in situ deposited on MgO in a fluidized bed reactor. In the hot zone of the reactor, sublimed ferrocene vapors were contacted with MgO powder fluidized by methane feed to produce Fe/MgO catalyst in situ. An annular tube was used to enhance the ferrocene and MgO contacting efficiency. Multi-wall as well as single-wall CNTs was grown on the Fe/MgO catalyst while falling down the reactor. The CNTs were continuously collected at the bottom of the reactor, only when MgO powder was used. The annular tube enhanced the contacting efficiency and improved both the quality and quantity of CNTs. The SEM and TEM micrographs of the products reveal that the CNTs are mostly entangled bundles with diameters of about 10-20 nm. Raman spectra show that the CNTs have low amount of amorphous/defected carbon with I{sub G}/I{sub D} ratios as high as 10.2 for synthesis at 900 deg. C. The RBM Raman peaks indicate formation of single-walled carbon nanotubes (SWNTs) of 1.0-1.2 nm diameter.

  4. Bimetal catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Ng, K. Y. Simon; Salley, Steve O.; Wang, Huali

    2017-10-03

    A catalyst comprises a carbide or nitride of a metal and a promoter element. The metal is selected from the group consisting of Mo, W, Co, Fe, Rh or Mn, and the promoter element is selected from the group consisting of Ni, Co, Al, Si, S or P, provided that the metal and the promoter element are different. The catalyst also comprises a mesoporous support having a surface area of at least about 170 m.sup.2 g.sup.-1, wherein the carbide or nitride of the metal and the promoter element is supported by the mesoporous support, and is in a non-sulfided form and in an amorphous form.

  5. Catalyst Architecture

    DEFF Research Database (Denmark)

    Kiib, Hans; Marling, Gitte; Hansen, Peter Mandal

    2014-01-01

    How can architecture promote the enriching experiences of the tolerant, the democratic, and the learning city - a city worth living in, worth supporting and worth investing in? Catalyst Architecture comprises architectural projects, which, by virtue of their location, context and their combination...... of programs, have a role in mediating positive social and/or cultural development. In this sense, we talk about architecture as a catalyst for: sustainable adaptation of the city’s infrastructure appropriate renovation of dilapidated urban districts strengthening of social cohesiveness in the city development...

  6. Noble metal ionic catalysts.

    Science.gov (United States)

    Hegde, M S; Madras, Giridhar; Patil, K C

    2009-06-16

    Because of growing environmental concerns and increasingly stringent regulations governing auto emissions, new more efficient exhaust catalysts are needed to reduce the amount of pollutants released from internal combustion engines. To accomplish this goal, the major pollutants in exhaust-CO, NO(x), and unburned hydrocarbons-need to be fully converted to CO(2), N(2), and H(2)O. Most exhaust catalysts contain nanocrystalline noble metals (Pt, Pd, Rh) dispersed on oxide supports such as Al(2)O(3) or SiO(2) promoted by CeO(2). However, in conventional catalysts, only the surface atoms of the noble metal particles serve as adsorption sites, and even in 4-6 nm metal particles, only 1/4 to 1/5 of the total noble metal atoms are utilized for catalytic conversion. The complete dispersion of noble metals can be achieved only as ions within an oxide support. In this Account, we describe a novel solution to this dispersion problem: a new solution combustion method for synthesizing dispersed noble metal ionic catalysts. We have synthesized nanocrystalline, single-phase Ce(1-x)M(x)O(2-delta) and Ce(1-x-y)Ti(y)M(x)O(2-delta) (M = Pt, Pd, Rh; x = 0.01-0.02, delta approximately x, y = 0.15-0.25) oxides in fluorite structure. In these oxide catalysts, Pt(2+), Pd(2+), or Rh(3+) ions are substituted only to the extent of 1-2% of Ce(4+) ion. Lower-valent noble metal ion substitution in CeO(2) creates oxygen vacancies. Reducing molecules (CO, H(2), NH(3)) are adsorbed onto electron-deficient noble metal ions, while oxidizing (O(2), NO) molecules are absorbed onto electron-rich oxide ion vacancy sites. The rates of CO and hydrocarbon oxidation and NO(x) reduction (with >80% N(2) selectivity) are 15-30 times higher in the presence of these ionic catalysts than when the same amount of noble metal loaded on an oxide support is used. Catalysts with palladium ion dispersed in CeO(2) or Ce(1-x)Ti(x)O(2) were far superior to Pt or Rh ionic catalysts. Therefore, we have demonstrated that the

  7. 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.

  8. Catalyst design for carbon nanotube growth using atomistic modeling

    International Nuclear Information System (INIS)

    Pint, Cary L; Bozzolo, Guillermo; Hauge, Robert

    2008-01-01

    The formation and stability of bimetallic catalyst particles, in the framework of carbon nanotube growth, is studied using the Bozzolo-Ferrante-Smith (BFS) method for alloys. Monte Carlo-Metropolis simulations with the BFS method are utilized in order to predict and study equilibrium configurations for nanoscale catalyst particles which are directly relevant to the catalyst state prior to growth of carbon nanotubes. At the forefront of possible catalyst combinations is the popular Fe-Mo bimetallic catalyst, which we have recently studied experimentally. We explain our experimental results, which indicate that the growth observed is dependent on the order of co-catalyst deposition, in the straightforward interpretation of BFS strain and chemical energy contributions toward the formation of Fe-Mo catalyst prior to growth. We find that the competition between the formation of metastable inner Mo cores and clusters of surface-segregated Mo atoms in Fe-Mo catalyst particles influences catalyst formation, and we investigate the role of Mo concentration and catalyst particle size in this process. Finally, we apply the same modeling approach to other prominent bimetallic catalysts and suggest that this technique can be a powerful tool to understand and manipulate catalyst design for highly efficient carbon nanotube growth

  9. Catalyst containing oxygen transport membrane

    Science.gov (United States)

    Christie, Gervase Maxwell; Wilson, Jamie Robyn; van Hassel, Bart Antonie

    2012-12-04

    A composite oxygen transport membrane having a dense layer, a porous support layer and an intermediate porous layer located between the dense layer and the porous support layer. Both the dense layer and the intermediate porous layer are formed from an ionic conductive material to conduct oxygen ions and an electrically conductive material to conduct electrons. The porous support layer has a high permeability, high porosity, and a high average pore diameter and the intermediate porous layer has a lower permeability and lower pore diameter than the porous support layer. Catalyst particles selected to promote oxidation of a combustible substance are located in the intermediate porous layer and in the porous support adjacent to the intermediate porous layer. The catalyst particles can be formed by wicking a solution of catalyst precursors through the porous support toward the intermediate porous layer.

  10. Residual deposits (residual soil)

    International Nuclear Information System (INIS)

    Khasanov, A.Kh.

    1988-01-01

    Residual soil deposits is accumulation of new formate ore minerals on the earth surface, arise as a result of chemical decomposition of rocks. As is well known, at the hyper genes zone under the influence of different factors (water, carbonic acid, organic acids, oxygen, microorganism activity) passes chemical weathering of rocks. Residual soil deposits forming depends from complex of geologic and climatic factors and also from composition and physical and chemical properties of initial rocks

  11. Coal catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Kroenig, W.

    1944-02-11

    Some considerations in the selection of a catalyst for the liquid phase of coal hydrogenation are discussed. Some of the previous history of such selections is mentioned. At one stage of the development, the principal catalyst had been iron sulfate (FeSO/sub 4/.7H/sub 2/O). Later, for reasons of cost and availability of large supplies, selections had turned to mixtures of iron sulfate and one or another of some iron oxide- and aluminum oxide-containing byproducts of aluminum manufacture, namely Bayermasse, Luxamsse, or Lautamasse. Much of the discussion centered on optimal proportions for such mixtures, particularly as related to pH values of resulting coal pastes. Upper Silesian coal was more alkaline than Ruhr coal, and Bayermasse, etc., were quite alkaline. Thus, since the iron sulfate served as a partial neutralizer for the coal as well as a catalyst, it seemed necessary to increase the proportions of iron sulfate in the catalyst mixture when processing coal of greater alkalinity. A further reason for a greater proportion of iron sulfate seemed to be that most of the catalytic activity of the iron came from the ferrous iron of iron sulfate rather than from the ferric iron of the other materials. Ferrous-ferric ratios also seemed to indicate that Luxmasse or Lautamasse might be better catalyst components than Bayermasse but their water content sometimes caused handling problems, so Bayermasse had been more widely used. Formation of deposits in the preheater was more likely due to the Bayermasse than to the iron sulfate; sodium sulfide could help to prevent them.

  12. Influence des catalyseurs hétérogènes sur le coprocessing d'un lignite du Berguedà avec un résidu de distillation sous vide Influence of Heterogeneous Catalysts on the Coprocessing of Berguedà Lignite with a Vacuum Residue

    Directory of Open Access Journals (Sweden)

    Moros A.

    2006-11-01

    Full Text Available Cet article étudie le co-traitement catalytique sous atmosphère d'hydrogène d'un lignite de la Catalogne (Espagne avec un résidu de distillation sous vide, en utilisant sept catalyseurs hétérogènes différents. Cinq d'entre eux sont de conception propre : quatre à base de fer avec des quantités respectives de 6, 10, 18 et 25 % en poids d'oxydes et un à base de fer-molybdène avec des quantités de 25 et 10 % respectivement. Tous ces catalyseurs sont déposés sur gamma-alumine. Les deux autres sont des catalyseurs commerciaux d'hydrotraitement à base de cobalt-molybdène et nickel-molybdène. Des essais à blanc ont été également réalisés avec de la gamma-alumine et sans catalyseur. Les résultats expérimentaux montrent que la performance des catalyseurs a été modifiée à cause de la présence d'une grande quantité de matière minérale contenue dans le charbon. Ces résultats sont confirmés par le fait que les trois valeurs maximales de conversion du charbon ont été obtenues lors de l'utilisation du catalyseur à base de fer à 25 %, avec ou sans molybdène, et sans catalyseur. Le pourcentage de fer dans les autres catalyseurs n'affecte pas de façon significative la conversion du charbon ou la production d'huile. Par ailleurs, la production d'huile augmente lors de l'utilisation des catalyseurs commerciaux d'hydrotraitement, mais la qualité des produits obtenus ne diffère pas réellement de celle obtenue avec les autres catalyseurs. Seven different heterogeneous catalysts are tested for the catalytic coprocessing of a Catalan lignite with vacuum residue under atmosphere of hydrogen. Four of these catalysts were iron-based catalysts supported on gamma-alumina with increasing loading of iron oxide. The fifth was a bimodal catalyst of iron and molybdenum. The last two catalysts were commercial hydrotreatment catalysts. Also, tests were conducted with gamma-alumina and without catalyst. The experimental results show that

  13. Eggshell waste as catalyst: A review.

    Science.gov (United States)

    Laca, Amanda; Laca, Adriana; Díaz, Mario

    2017-07-15

    Agricultural wastes are some of the most emerging problems in food industries because of their disposal cost. However, it is also an opportunity for the bioeconomy society if new uses for these residual materials can be found. Eggshells, considered a hazardous waste by UE regulations, are discarded, amounting hundreds of thousands of tonnes worldwide. This egg processing waste is a valuable source material, which can be used in different fields such as fodder or fertilizer production. Additionally, this residue offers interesting characteristics to be used in other applications, like its employment as an environment-friendly catalyst. In the present review we provide a global view of eggshell waste uses as catalyst in different processes. According to reviewed researching works, a huge variety of added value products can be obtained by using this catalyst which emphasised the interest of further investigations in order to widen the possible uses of this cheap green catalyst. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Recovery of precious metals from low-grade automobile shredder residue: A novel approach for the recovery of nanozero-valent copper particles.

    Science.gov (United States)

    Singh, Jiwan; Lee, Byeong-Kyu

    2016-02-01

    The presence of precious metals (PMs) in low-grade automobile shredder residue (ASR) makes it attractive for recycling. This study investigated the leaching and recovery characteristics of two PMs (Cu and Ag) and two heavy metals (Mn and Co) from ASR. The effects of H2O2, leaching temperature, liquid to solid (L/S) ratio, and particle size on metal leaching were determined in an aqueous solution of 0.5M nitric acid. The metal leaching rate was increased with increasing nitric acid concentration, amount of H2O2, L/S ratio and temperature. The leaching kinetics was analyzed by using a second-order reaction model. In the analysis of leaching kinetics, the metal leaching data were well fitted (R(2)⩾0.99) with the second-order reaction model. The activation energy (kJ/mol) for metal leaching was 39.6 for Cu, 17.1 for Ag, 17.3 for Mn and 29.2 for Co. Metal recovery was carried out by fractional precipitation with the addition of advanced Fenton's regent. Metal recovery efficiency was increased to 99.95% for Cu, 99.8% for Mn, 90.0% for Ag and 96.46% for Co with the advanced Fenton's regent. In particular, a novel finding of the PM recovery is that Cu can also be recovered directly from the leachate of ASR in the form of zero-valent copper (ZVC) nanoparticles (NPs). Hydrometallurgical recovery of the metals from ASR using nitric acid is highly efficient. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Catalyst Architecture

    DEFF Research Database (Denmark)

    Catalyst Architecture’ takes its point of departure in a broadened understanding of the role of architecture in relation to developmental problems in large cities. Architectural projects frame particular functions and via their form language, they can provide the user with an aesthetic experience....... The broadened understanding of architecture consists in that an architectural project, by virtue of its placement in the context and of its composition of programs, can have a mediating role in a positive or cultural development of the district in question. In this sense, we talk about architecture as catalyst...... cities on the planet have growing pains and social cohesiveness is under pressure from an increased difference between rich and poor, social segregation, ghettoes, immigration of guest workers and refugees, commercial mass tourism etc. In this context, it is important to ask which role architecture...

  16. Core-shell H-ZSM-5/silicalite-1 composites: Brønsted acidity and catalyst deactivation at the individual particle level.

    Science.gov (United States)

    Mores, Davide; Stavitski, Eli; Verkleij, Suzanna P; Lombard, Antoinette; Cabiac, Amandine; Rouleau, Loïc; Patarin, Joël; Simon-Masseron, Angélique; Weckhuysen, Bert M

    2011-09-21

    A combination of in situ UV-Vis and confocal fluorescence micro-spectroscopy is applied to investigate the influence of an external silicalite-1 shell on the Brønsted acidity and coke formation process of individual H-ZSM-5 zeolite crystals. Three probe reactions were used: oligomerization of styrene, methanol-to-olefin (MTO) conversion and aromatization of light naphtha (LNA) derivatives. Oligomerization of styrene leads to the formation of optically active carbocationic oligomers. Different styrene substitutions indicate the conversion ability of the catalyst acid core, a preferred alignment of the oligomers within the straight zeolite channels and a Brønsted acidity gradient throughout the zeolite crystal. Both the MTO conversion and the LNA process lead to limited carbonaceous deposition within the external silicalite-1 layer. This outer shell furthermore prevents the growth of extended coke species at the zeolite external surface. During MTO, the formation of carbonaceous compounds initiates at the center of the H-ZSM-5 zeolite core and expands towards the zeolite exterior. This coke build-up starts with a 420 nm UV-Vis absorption band, assigned to methyl-substituted aromatic carbocations, and a second band around 550 nm, which is indicative of their growth towards larger conjugated systems. Aromatization of linear and branched C5 paraffins causes negligible darkening of the zeolite crystals though it forms fluorescent coke deposits and their precursors within the H-ZSM-5 catalyst. Olefin homologues on the contrary cause pronounced darkening of the zeolite composite. Methyl-branching of these reactants slows down the coke formation rate and produces carbonaceous species that are more restricted in their molecular size.

  17. Rhenium Nanochemistry for Catalyst Preparation

    Directory of Open Access Journals (Sweden)

    Vadim G. Kessler

    2012-08-01

    Full Text Available The review presents synthetic approaches to modern rhenium-based catalysts. Creation of an active center is considered as a process of obtaining a nanoparticle or a molecule, immobilized within a matrix of the substrate. Selective chemical routes to preparation of particles of rhenium alloys, rhenium oxides and the molecules of alkyltrioxorhenium, and their insertion into porous structure of zeolites, ordered mesoporous MCM matrices, anodic mesoporous alumina, and porous transition metal oxides are considered. Structure-property relationships are traced for these catalysts in relation to such processes as alkylation and isomerization, olefin metathesis, selective oxidation of olefins, methanol to formaldehyde conversion, etc.

  18. Photocatalytic H2 Evolution Using Different Commercial TiO2 Catalysts Deposited with Finely Size-Tailored Au Nanoparticles: Critical Dependence on Au Particle Size

    Directory of Open Access Journals (Sweden)

    Ákos Kmetykó

    2014-11-01

    Full Text Available One weight percent of differently sized Au nanoparticles were deposited on two commercially available TiO2 photocatalysts: Aeroxide P25 and Kronos Vlp7000. The primary objective was to investigate the influence of the noble metal particle size and the deposition method on the photocatalytic activity. The developed synthesis method involves a simple approach for the preparation of finely-tuned Au particles through variation of the concentration of the stabilizing agent. Au was deposited on the TiO2 surface by photo- or chemical reduction, using trisodium citrate as a size-tailoring agent. The Au-TiO2 composites were synthetized by in situ reduction or by mixing the titania suspension with a previously prepared gold sol. The H2 production activities of the samples were studied in aqueous TiO2 suspensions irradiated with near-UV light in the absence of dissolved O2, with oxalic acid or methanol as the sacrificial agent. The H2 evolution rates proved to be strongly dependent on Au particle size: the highest H2 production rate was achieved when the Au particles measured ~6 nm.

  19. Photocatalytic H2 Evolution Using Different Commercial TiO2 Catalysts Deposited with Finely Size-Tailored Au Nanoparticles: Critical Dependence on Au Particle Size

    Science.gov (United States)

    Kmetykó, Ákos; Mogyorósi, Károly; Pusztai, Péter; Radu, Teodora; Kónya, Zoltán; Dombi, András; Hernádi, Klára

    2014-01-01

    One weight percent of differently sized Au nanoparticles were deposited on two commercially available TiO2 photocatalysts: Aeroxide P25 and Kronos Vlp7000. The primary objective was to investigate the influence of the noble metal particle size and the deposition method on the photocatalytic activity. The developed synthesis method involves a simple approach for the preparation of finely-tuned Au particles through variation of the concentration of the stabilizing agent. Au was deposited on the TiO2 surface by photo- or chemical reduction, using trisodium citrate as a size-tailoring agent. The Au-TiO2 composites were synthetized by in situ reduction or by mixing the titania suspension with a previously prepared gold sol. The H2 production activities of the samples were studied in aqueous TiO2 suspensions irradiated with near-UV light in the absence of dissolved O2, with oxalic acid or methanol as the sacrificial agent. The H2 evolution rates proved to be strongly dependent on Au particle size: the highest H2 production rate was achieved when the Au particles measured ~6 nm. PMID:28788264

  20. An introduction to catalyst

    International Nuclear Information System (INIS)

    Jeon, Hak Je

    1988-11-01

    This book explains basic conception of catalyst such as definition, velocity of chemical reaction and velocity of catalyst reaction, absorption with absorption energy and chemical absorption, pore structure with the role of pore and measurement of pore structure, catalyst activity on solid structure, electrical property on catalyst activity, choice and design of catalyst, catalytic reaction with reaction velocity and chemical equilibrium and reaction velocity model, measurement of reaction velocity and material analysis, catalyst for mixed compound, catalyst for solid acid and catalyst for supported metal.

  1. Characterization of individual ice residual particles by the single droplet freezing method: a case study in the Asian dust outflow region

    Science.gov (United States)

    Iwata, Ayumi; Matsuki, Atsushi

    2018-02-01

    In order to better characterize ice nucleating (IN) aerosol particles in the atmosphere, we investigated the chemical composition, mixing state, and morphology of atmospheric aerosols that nucleate ice under conditions relevant for mixed-phase clouds. Five standard mineral dust samples (quartz, K-feldspar, Na-feldspar, Arizona test dust, and Asian dust source particles) were compared with actual aerosol particles collected from the west coast of Japan (the city of Kanazawa) during Asian dust events in February and April 2016. Following droplet activation by particles deposited on a hydrophobic Si (silicon) wafer substrate under supersaturated air, individual IN particles were located using an optical microscope by gradually cooling the temperature to -30 °C. For the aerosol samples, both the IN active particles and non-active particles were analyzed individually by atomic force microscopy (AFM), micro-Raman spectroscopy, and scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX). Heterogeneous ice nucleation in all standard mineral dust samples tested in this study was observed at consistently higher temperatures (e.g., -22.2 to -24.2 °C with K-feldspar) than the homogeneous freezing temperature (-36.5 °C). Meanwhile, most of the IN active atmospheric particles formed ice below -28 °C, i.e., at lower temperatures than the standard mineral dust samples of pure components. The most abundant IN active particles above -30 °C were predominantly irregular solid particles that showed clay mineral characteristics (or mixtures of several mineral components). Other than clay, Ca-rich particles internally mixed with other components, such as sulfate, were also regarded as IN active particle types. Moreover, sea salt particles were predominantly found in the non-active fraction, and internal mixing with sea salt clearly acted as a significant inhibiting agent for the ice nucleation activity of mineral dust particles. Also, relatively

  2. Characterization of individual ice residual particles by the single droplet freezing method: a case study in the Asian dust outflow region

    Directory of Open Access Journals (Sweden)

    A. Iwata

    2018-02-01

    Full Text Available In order to better characterize ice nucleating (IN aerosol particles in the atmosphere, we investigated the chemical composition, mixing state, and morphology of atmospheric aerosols that nucleate ice under conditions relevant for mixed-phase clouds. Five standard mineral dust samples (quartz, K-feldspar, Na-feldspar, Arizona test dust, and Asian dust source particles were compared with actual aerosol particles collected from the west coast of Japan (the city of Kanazawa during Asian dust events in February and April 2016. Following droplet activation by particles deposited on a hydrophobic Si (silicon wafer substrate under supersaturated air, individual IN particles were located using an optical microscope by gradually cooling the temperature to −30 °C. For the aerosol samples, both the IN active particles and non-active particles were analyzed individually by atomic force microscopy (AFM, micro-Raman spectroscopy, and scanning electron microscopy (SEM coupled with energy dispersive X-ray spectroscopy (EDX. Heterogeneous ice nucleation in all standard mineral dust samples tested in this study was observed at consistently higher temperatures (e.g., −22.2 to −24.2 °C with K-feldspar than the homogeneous freezing temperature (−36.5 °C. Meanwhile, most of the IN active atmospheric particles formed ice below −28 °C, i.e., at lower temperatures than the standard mineral dust samples of pure components. The most abundant IN active particles above −30 °C were predominantly irregular solid particles that showed clay mineral characteristics (or mixtures of several mineral components. Other than clay, Ca-rich particles internally mixed with other components, such as sulfate, were also regarded as IN active particle types. Moreover, sea salt particles were predominantly found in the non-active fraction, and internal mixing with sea salt clearly acted as a significant inhibiting agent for the ice nucleation activity of mineral

  3. Controlled growth of carbon nanofibers using plasma enhanced chemical vapor deposition: Effect of catalyst thickness and gas ratio

    International Nuclear Information System (INIS)

    Saidin, M.A.R.; Ismail, A.F.; Sanip, S.M.; Goh, P.S.; Aziz, M.; Tanemura, M.

    2012-01-01

    The characteristics of carbon nanofibers (CNFs) grown, using direct current plasma enhanced chemical vapor deposition system reactor under various acetylene to ammonia gas ratios and different catalyst thicknesses were studied. Nickel/Chromium-glass (Ni/Cr-glass) thin film catalyst was employed for the growth of CNF. The grown CNFs were then characterized using Raman spectroscopy, field emission scanning electron microscopy and transmission electron microscopy (TEM). Raman spectroscopy showed that the Ni/Cr-glass with thickness of 15 nm and gas ratio acetylene to ammonia of 1:3 produced CNFs with the lowest I D /I G value (the relative intensity of D-band to G-band). This indicated that this catalyst thickness and gas ratio value is the optimum combination for the synthesis of CNFs under the conditions studied. TEM observation pointed out that the CNFs produced have 104 concentric walls and the residual catalyst particles were located inside the tubes of CNFs. It was also observed that structural morphology of the grown CNFs was influenced by acetylene to ammonia gas ratio and catalyst thickness.

  4. Controlled growth of carbon nanofibers using plasma enhanced chemical vapor deposition: Effect of catalyst thickness and gas ratio

    Energy Technology Data Exchange (ETDEWEB)

    Saidin, M.A.R. [Advanced Membrane Technology Research Centre (AMTEC), Universiti Teknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia); Ismail, A.F., E-mail: afauzi@utm.my [Advanced Membrane Technology Research Centre (AMTEC), Universiti Teknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia); Sanip, S.M.; Goh, P.S.; Aziz, M. [Advanced Membrane Technology Research Centre (AMTEC), Universiti Teknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia); Tanemura, M. [Department of Frontier Material, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan)

    2012-01-31

    The characteristics of carbon nanofibers (CNFs) grown, using direct current plasma enhanced chemical vapor deposition system reactor under various acetylene to ammonia gas ratios and different catalyst thicknesses were studied. Nickel/Chromium-glass (Ni/Cr-glass) thin film catalyst was employed for the growth of CNF. The grown CNFs were then characterized using Raman spectroscopy, field emission scanning electron microscopy and transmission electron microscopy (TEM). Raman spectroscopy showed that the Ni/Cr-glass with thickness of 15 nm and gas ratio acetylene to ammonia of 1:3 produced CNFs with the lowest I{sub D}/I{sub G} value (the relative intensity of D-band to G-band). This indicated that this catalyst thickness and gas ratio value is the optimum combination for the synthesis of CNFs under the conditions studied. TEM observation pointed out that the CNFs produced have 104 concentric walls and the residual catalyst particles were located inside the tubes of CNFs. It was also observed that structural morphology of the grown CNFs was influenced by acetylene to ammonia gas ratio and catalyst thickness.

  5. deNOx catalysts for biomass combustion

    DEFF Research Database (Denmark)

    Kristensen, Steffen Buus

    The present thesis revolves around the challenges involved in removal of nitrogen oxides in biomass fired power plants. Nitrogen oxides are unwanted byproducts formed to some extent during almost any combustion. In coal fired plants these byproducts are removed by selective catalytic reduction......, however the alkali in biomass complicate matters. Alkali in biomass severely deactivates the catalyst used for the selective catalytic reduction in matter of weeks, hence a more alkali resistant catalyst is needed. In the thesis a solution to the problem is presented, the nano particle deNOx catalyst...

  6. Nb-doped TiO2 cathode catalysts for oxygen reduction reaction of polymer electrolyte fuel cells

    KAUST Repository

    Arashi, Takuya

    2014-09-01

    Nb-doped TiO2 particles were studied as electrocatalysts for the oxygen reduction reaction (ORR) under acidic conditions. The Nb-doped TiN nanoparticles were first synthesized by meso-porous C3N4 and then fully oxidized to Nb-doped TiO2 by immersing in 0.1 M H 2SO4 at 353 K for 24 h. Although the ORR activity of the as-obtained sample was low, a H2 treatment at relatively high temperature (1173 K) dramatically improved the ORR performance. An onset potential as high as 0.82 VRHE was measured. No degradation of the catalysts was observed during the oxidation-reduction cycles under the ORR condition for over 127 h. H2 treatment at temperatures above 1173 K caused the formation of a Ti4O7 phase, resulting in a decrease in ORR current. Elemental analysis indicated that the Nb-doped TiO 2 contained 25 wt% residual carbon. Calcination in air at 673 or 973 K eliminated the residual carbon in the catalyst, which was accompanied by a dramatic decrease in ORR activity. This post-calcination process may reduce the conductivity of the sample by filling the oxygen vacancies, and the carbon residue in the particle aggregates may enhance the electrocatalytic activity for ORR. The feasibility of using conductive oxide materials as electrocatalysts is discussed. © 2013 Elsevier B.V.

  7. Amorphous molybdenum sulfides as hydrogen evolution catalysts.

    Science.gov (United States)

    Morales-Guio, Carlos G; Hu, Xile

    2014-08-19

    Providing energy for a population projected to reach 9 billion people within the middle of this century is one of the most pressing societal issues. Burning fossil fuels at a rate and scale that satisfy our near-term demand will irreversibly damage the living environment. Among the various sources of alternative and CO2-emission-free energies, the sun is the only source that is capable of providing enough energy for the whole world. Sunlight energy, however, is intermittent and requires an efficient storage mechanism. Sunlight-driven water splitting to make hydrogen is widely considered as one of the most attractive methods for solar energy storage. Water splitting needs a hydrogen evolution catalyst to accelerate the rate of hydrogen production and to lower the energy loss in this process. Precious metals such as Pt are superior catalysts, but they are too expensive and scarce for large-scale applications. In this Account, we summarize our recent research on the preparation, characterization, and application of amorphous molybdenum sulfide catalysts for the hydrogen evolution reaction. The catalysts can be synthesized by electrochemical deposition under ambient conditions from readily available and inexpensive precursors. The catalytic activity is among the highest for nonprecious catalysts. For example, at a loading of 0.2 mg/cm(2), the optimal catalyst delivers a current density of 10 mA/cm(2) at an overpotential of 160 mV. The growth mechanism of the electrochemically deposited film catalysts was revealed by an electrochemical quartz microcrystal balance study. While different electrochemical deposition methods produce films with different initial compositions, the active catalysts are the same and are identified as a "MoS(2+x)" species. The activity of the film catalysts can be further promoted by divalent Fe, Co, and Ni ions, and the origins of the promotional effects have been probed. Highly active amorphous molybdenum sulfide particles can also be prepared

  8. An improved method of preparation of nanoparticular metal oxide catalysts

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention concerns an improved method of preparation of nanoparticular vanadium oxide/anatase titania catalysts having a narrow particle size distribution. In particular, the invention concerns preparation of nanoparticular vanadium oxide/anatase titania catalyst precursors comprising...... combustible crystallization seeds upon which the catalyst metal oxide is coprecipitated with the carrier metal oxide, which crystallization seeds are removed by combustion in a final calcining step....

  9. Heterogeneous Tin Catalysts Applied to the Esterification and Transesterification Reactions

    Directory of Open Access Journals (Sweden)

    Márcio José da Silva

    2013-01-01

    Full Text Available The interest in the development of efficient and environmentally benign catalysts for esters synthesis has increased exponentially, mainly due to the demand for biodiesel. In general, fatty esters are used as bioadditive, cosmetic ingredients, polymers, and, more recently, biofuel. Nevertheless, most of the production processes use nonrecyclable and homogenous alkaline catalysts, which results in the reactors corrosion, large generation of effluents, and residues on the steps of separation and catalyst neutralization. Heterogeneous acid catalysts can answer these demands and are an environmentally benign alternative extensively explored. Remarkably, solid acid catalysts based on tin have been shown highly attractive for the biodiesel production, mainly via FFA esterification reactions. This review describes important features related to be the synthesis, stability to, and activity of heterogeneous tin catalysts in biodiesel production reactions.

  10. Reduction of a Ni/Spinel Catalyst for Methane Reforming

    DEFF Research Database (Denmark)

    Kehres, Jan; Andreasen, Jens Wenzel; Fløystad, Jostein Bø

    2015-01-01

    microscopy (HRTEM) was performed on the fresh catalyst sample. The Ni particles in the fresh catalyst sample were observed to exhibit a Ni/NiO core/shell structure. A decrease of the Ni lattice parameter is observed during the reduction in a temperature interval from 413 – 453 K, which can be related...

  11. Residuation theory

    CERN Document Server

    Blyth, T S; Sneddon, I N; Stark, M

    1972-01-01

    Residuation Theory aims to contribute to literature in the field of ordered algebraic structures, especially on the subject of residual mappings. The book is divided into three chapters. Chapter 1 focuses on ordered sets; directed sets; semilattices; lattices; and complete lattices. Chapter 2 tackles Baer rings; Baer semigroups; Foulis semigroups; residual mappings; the notion of involution; and Boolean algebras. Chapter 3 covers residuated groupoids and semigroups; group homomorphic and isotone homomorphic Boolean images of ordered semigroups; Dubreil-Jacotin and Brouwer semigroups; and loli

  12. Acetone production using silicon nanoparticles and catalyst compositions

    KAUST Repository

    Chaieb, Sahraoui

    2015-12-10

    Embodiments of the present disclosure provide for a catalytic reaction to produce acetone, a catalyst that include a mixture of silicon particles (e.g., about 1 to 20 nm in diameter) and a solvent, and the like.

  13. Support Functionalization To Retard Ostwald Ripening in Copper Methanol Synthesis Catalysts

    NARCIS (Netherlands)

    van den Berg, Roy|info:eu-repo/dai/nl/358212049; Parmentier, Tanja E.; Elkjaer, Christian F.; Gommes, Cedric J.; Sehested, Jens; Helveg, Stig; de Jongh, Petra E.|info:eu-repo/dai/nl/186125372; de Jong, Krijn P.|info:eu-repo/dai/nl/06885580X

    A main reason for catalyst deactivation in supported catalysts for methanol synthesis is copper particle growth. We have functionalized the support surface in order to suppress the formation and/or transport of mobile copper species and thereby catalyst deactivation. A Stober silica support was

  14. Bifunctional catalysts for the direct production of liquid fuels from syngas

    NARCIS (Netherlands)

    Sartipi, S.

    2014-01-01

    Design and development of catalyst formulations that maximize the direct production of liquid fuels by combining Fischer-Tropsch synthesis (FTS), hydrocarbon cracking, and isomerization into one single catalyst particle (bifunctional FTS catalyst) have been investigated in this thesis. To achieve

  15. Influence of reaction parameters on the hydrogenolysis of hydroxymatairesinol over carbon nanofibre supported palladium catalysts

    NARCIS (Netherlands)

    Bernas, H.; Plomp, A.J.|info:eu-repo/dai/nl/304837598; Bitter, J.H.|info:eu-repo/dai/nl/160581435; Murzin, D.Y.

    2008-01-01

    The influence of catalyst particle size, stirring rate, catalyst mass (0.2–0.6 g), reaction temperature (60–70 C), and reactant concentration (1.3–4 mmol/L, with constant reactant/catalyst ratio) on the hydrogenolysis of the lignan hydroxymatairesinol (HMR) to matairesinol (MAT) was studied under

  16. Sol-gel based oxidation catalyst and coating system using same

    Science.gov (United States)

    Watkins, Anthony N. (Inventor); Leighty, Bradley D. (Inventor); Oglesby, Donald M. (Inventor); Patry, JoAnne L. (Inventor); Schryer, Jacqueline L. (Inventor)

    2010-01-01

    An oxidation catalyst system is formed by particles of an oxidation catalyst dispersed in a porous sol-gel binder. The oxidation catalyst system can be applied by brush or spray painting while the sol-gel binder is in its sol state.

  17. Sintering of nickel steam reforming catalysts

    DEFF Research Database (Denmark)

    Sehested, Jens; Larsen, Niels Wessel; Falsig, Hanne

    2014-01-01

    The lifetimes of heterogeneous catalysts in many widely used industrial processes are determined by the loss of active surface area. In this context, the underlying physical sintering mechanism and quantitative information about the rate of sintering at industrial conditions are relevant....... In this paper, particle migration and coalescence in nickel steam reforming catalysts is studied. Density functional theory calculations indicate that Ni-OH dominate nickel transport at nickel surfaces in the presence of steam and hydrogen as Ni-OH has the lowest combined energies of formation and diffusion...... compared to other potential nickel transport species. The relation between experimental catalyst sintering data and the effective mass diffusion constant for Ni-OH is established by numerical modelling of the particle migration and coalescence process. Using this relation, the effective mass diffusion...

  18. Investigation on the effect of mixed rapeseed stalk residues with wood particles, and mixing of melamine and urea formaldehyde resin on properties of manufactured particleboard

    Directory of Open Access Journals (Sweden)

    Behzad Kord

    2016-09-01

    Full Text Available In this study, the possibility of using the rapeseed stalk mixed with industrial wood particles for manufacturing particleboard with target density of 0.7 gr/cm3 was considered. Variable factors such as mixing ratios of rapeseed stalk with industrial wood particles at five mixing levels of (0-100, 25-75, 50-50, 75-25 and 100-0 percent, mixing ratios of melamine resin with urea formaldehyde at three levels of 0-100, 15-85 and 30-70 percent, and kind of board at two levels of homogenate and layer were considered. 10 percent resin based on oven dried weight of particles, 2 percent catalyzer based on oven dried weight of resin, press temperature and time with 170 OC and 7 minute, press pressure and rate with 30 Kg/cm3 and 4.5 mm/min were fixed. Then, the boards were manufactured and the physical and mechanical properties including modulus of rupture, modulus of elasticity, internal bonding, water absorption and thickness swelling were measured according to EN standard. Results indicated that the modulus of rupture, modulus of elasticity, water absorption and thickness swelling of boards increased with increase rapeseed stalk loading; however, the internal bonding decreased. Also, the use of melamine urea formaldehyde resin caused to improve the mechanical strength and dimensional stability in the samples.

  19. Ni-SiO2 Catalysts for the Carbon Dioxide Reforming of Methane: Varying Support Properties by Flame Spray Pyrolysis

    Directory of Open Access Journals (Sweden)

    Emma C. Lovell

    2015-03-01

    Full Text Available Silica particles were prepared by flame spray pyrolysis (FSP as a support for nickel catalysts. The impact of precursor feed rate (3, 5 and 7 mL/min during FSP on the silica characteristics and the ensuing effect on catalytic performance for the carbon dioxide, or dry, reforming of methane (DRM was probed. Increasing the precursor feed rate: (i progressively lowered the silica surface area from ≈340 m2/g to ≈240 m2/g; (ii altered the silanol groups on the silica surface; and (iii introduced residual carbon-based surface species to the sample at the highest feed rate. The variations in silica properties altered the (5 wt % nickel deposit characteristics which in turn impacted on the DRM reaction. As the silica surface area increased, the nickel dispersion increased which improved catalyst performance. The residual carbon-based species also appeared to improve nickel dispersion, and in turn catalyst activity, although not to the same extent as the change in silica surface area. The findings illustrate both the importance of silica support characteristics on the catalytic performance of nickel for the DRM reaction and the capacity for using FSP to control these characteristics.

  20. Methods of producing epoxides from alkenes using a two-component catalyst system

    Science.gov (United States)

    Kung, Mayfair C.; Kung, Harold H.; Jiang, Jian

    2013-07-09

    Methods for the epoxidation of alkenes are provided. The methods include the steps of exposing the alkene to a two-component catalyst system in an aqueous solution in the presence of carbon monoxide and molecular oxygen under conditions in which the alkene is epoxidized. The two-component catalyst system comprises a first catalyst that generates peroxides or peroxy intermediates during oxidation of CO with molecular oxygen and a second catalyst that catalyzes the epoxidation of the alkene using the peroxides or peroxy intermediates. A catalyst system composed of particles of suspended gold and titanium silicalite is one example of a suitable two-component catalyst system.

  1. Design of porous nanostructured solid catalysts

    DEFF Research Database (Denmark)

    Abildstrøm, Jacob Oskar

    and activity. The basis of the catalyst is the yolk-shell particles consisting of small platinum nanoparticles and a shell of nitrogen doped carbon with graphitic elements. The carbon shell will be activated with potassium hydroxide to generate some microporosity in the shell, to improve the diffusion...

  2. Application of colloidal chemistry in aqueous phase to the preparation of supported metallic catalysts: particles size and aggregation control; Application de la chimie colloidale en phase aqueuse a la preparation de catalyseurs metalliques supportes: controle de la taille et de l`etat d`agregation des particules

    Energy Technology Data Exchange (ETDEWEB)

    Pages, T.

    1998-09-16

    This work is an application of colloidal chemistry in aqueous phase on supported metal catalyst preparation. The objective is the control of particle size and aggregation. The preparation of the materials was achieved in two steps: - the synthesis of PdO hydrosols was obtained by two ways: neutralisation of the solution containing metallic salt by adding alkaline solution or by thermo-hydrolysis; the sols were then deposited on carriers (Al{sub 2}O{sub 3}, SIO{sub 2}). The use of partial charge model allowed us to determine the complexes that were able to generate PdO. The preparation of PdO from Pd(H{sub 2}O){sub 4}{sup 2+} was studied and a mechanism of oxide formation was elaborated. The neutralisation of Pd(H{sub 2}O){sub 4}{sup 2+} obtained by adding alkaline solution led to particles with an average size of 1.8 nm and a narrow particle size distribution. Only the thermo-hydrolysis of Pd(H{sub 2}O){sub 4}{sup 2+} led to particles which size is higher than 3.0 nm. In the last case, particle size is controlled by the precursor concentration (Pd(H{sub 2}O){sub 2}(OH){sub 2}) generated in the medium. We have demonstrated that particle aggregation in the sol depends on the Ph and the way of preparation. It can be controlled by adding complexing anions (Cl{sup -}, NO{sub 2}{sup -}). Concerning the deposition of sols on carriers, it led to isolated or aggregated particles according to experimental conditions. Particle size was not modified during the deposition. Moreover, in our experimental conditions, reduction of particles did not modify particle size and aggregation. An application of this original way of preparation on catalysis allowed us to demonstrate the interest of controlling particle size and aggregation. (author) 186 refs.

  3. Design of heterogeneous catalysts

    DEFF Research Database (Denmark)

    Frey, Anne Mette

    The title of my PhD thesis is “Design of Heterogeneous Catalysts”. Three reactions have been investigated: the methanation reaction, the Fischer-Tropsch reaction, and the NH3-based selective catalytic reduction (SCR) of NO. The experimental work performed in connection with the methanation reaction...... hydrogenation. For both systems a maximum in catalytic activity was found for some of the bimetallic catalysts being superior to the monometallic catalysts. This resulted in volcano curves for all investigated systems. In the Fischer-Tropsch reaction promotion of cobalt catalysts with manganese was studied...... well, and the best catalyst prepared had a C5+ yield almost a factor of two higher than a standard air calcined Co catalyst. In the NH3-SCR reaction it is desirable to develop an active and stable catalyst for NOx removal in automotive applications, since the traditionally used vanadium-based catalyst...

  4. Potential application of palladium nanoparticles as selective recyclable hydrogenation catalysts

    International Nuclear Information System (INIS)

    Mukherjee, DebKumar

    2008-01-01

    The search for more efficient catalytic systems that might combine the advantages of both homogeneous (catalyst modulation) and heterogeneous (catalyst recycling) catalysis is one of the most exciting challenges of modern chemistry. More recently with the advances of nanochemistry, it has been possible to prepare soluble analogues of heterogeneous catalysts. These nanoparticles are generally stabilized against aggregation into larger particles by electrostatic or steric protection. Herein we demonstrate the use of room temperature ionic liquid for the stabilization of palladium nanoparticles that are recyclable catalysts for the hydrogenation of carbon-carbon double bonds and application of these catalysts to the selective hydrogenation of internal or terminal C=C bonds in unsaturated primary alcohols. The particles suspended in room temperature ionic liquid show no metal aggregation or loss of catalytic activity even on prolonged use

  5. Apparatus and Process for Controlled Nanomanufacturing Using Catalyst Retaining Structures

    Science.gov (United States)

    Nguyen, Cattien (Inventor)

    2013-01-01

    An apparatus and method for the controlled fabrication of nanostructures using catalyst retaining structures is disclosed. The apparatus includes one or more modified force microscopes having a nanotube attached to the tip portion of the microscopes. An electric current is passed from the nanotube to a catalyst layer of a substrate, thereby causing a localized chemical reaction to occur in a resist layer adjacent the catalyst layer. The region of the resist layer where the chemical reaction occurred is etched, thereby exposing a catalyst particle or particles in the catalyst layer surrounded by a wall of unetched resist material. Subsequent chemical vapor deposition causes growth of a nanostructure to occur upward through the wall of unetched resist material having controlled characteristics of height and diameter and, for parallel systems, number density.

  6. 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.

  7. Influence of reaction parameters on the hydrogenolysis of hydroxymatairesinol over carbon nanofibre supported palladium catalysts

    OpenAIRE

    Bernas, H.; Plomp, A.J.; Bitter, J.H.; Murzin, D.Y.

    2008-01-01

    The influence of catalyst particle size, stirring rate, catalyst mass (0.2–0.6 g), reaction temperature (60–70 C), and reactant concentration (1.3–4 mmol/L, with constant reactant/catalyst ratio) on the hydrogenolysis of the lignan hydroxymatairesinol (HMR) to matairesinol (MAT) was studied under hydrogen atmosphere using a carbon nanofibre supported palladium catalyst. When the temperature or HMR concentration was increased, the reaction rate increased as expected. However, the reaction rate...

  8. Do wood-based panels made with agro-industrial residues provide environmentally benign alternatives? An LCA case study of sugarcane bagasse addition to particle board manufacturing

    DEFF Research Database (Denmark)

    Silva, Diogo Aparecido Lopes; Lahr, Francisco Antonio Rocco; Pavan, Ana Laura Raymundo

    2014-01-01

    subsystems: bagasse generation, bagasse distribution, and PSB production. For the inventory of PSB, dataset from two previous LCA studies related to the conventional particle board production and the ethanol life cycle for the Brazilian context were used. The allocation criterion for the bagasse generation...... were analyzed to evaluate the influence of the allocation criteria and the consumption of sugarcane bagasse.All hotspots identified by CML and USETox methods are mainly related to the PSB production subsystem (24–100 % of impacts) due to heavy fuel oil, electricity, and urea-formaldehyde resin supply...

  9. Design criteria for stable Pt/C fuel cell catalysts

    Directory of Open Access Journals (Sweden)

    Josef C. Meier

    2014-01-01

    Full Text Available Platinum and Pt alloy nanoparticles supported on carbon are the state of the art electrocatalysts in proton exchange membrane fuel cells. To develop a better understanding on how material design can influence the degradation processes on the nanoscale, three specific Pt/C catalysts with different structural characteristics were investigated in depth: a conventional Pt/Vulcan catalyst with a particle size of 3–4 nm and two Pt@HGS catalysts with different particle size, 1–2 nm and 3–4 nm. Specifically, Pt@HGS corresponds to platinum nanoparticles incorporated and confined within the pore structure of the nanostructured carbon support, i.e., hollow graphitic spheres (HGS. All three materials are characterized by the same platinum loading, so that the differences in their performance can be correlated to the structural characteristics of each material. The comparison of the activity and stability behavior of the three catalysts, as obtained from thin film rotating disk electrode measurements and identical location electron microscopy, is also extended to commercial materials and used as a basis for a discussion of general fuel cell catalyst design principles. Namely, the effects of particle size, inter-particle distance, certain support characteristics and thermal treatment on the catalyst performance and in particular the catalyst stability are evaluated. Based on our results, a set of design criteria for more stable and active Pt/C and Pt-alloy/C materials is suggested.

  10. Novel Anode Catalyst for Direct Methanol Fuel Cells

    Directory of Open Access Journals (Sweden)

    S. Basri

    2014-01-01

    Full Text Available PtRu catalyst is a promising anodic catalyst for direct methanol fuel cells (DMFCs but the slow reaction kinetics reduce the performance of DMFCs. Therefore, this study attempts to improve the performance of PtRu catalysts by adding nickel (Ni and iron (Fe. Multiwalled carbon nanotubes (MWCNTs are used to increase the active area of the catalyst and to improve the catalyst performance. Electrochemical analysis techniques, such as energy dispersive X-ray spectrometry (EDX, X-ray diffraction (XRD, field emission scanning electron microscopy (FESEM, and X-ray photoelectron spectroscopy (XPS, are used to characterize the kinetic parameters of the hybrid catalyst. Cyclic voltammetry (CV is used to investigate the effects of adding Fe and Ni to the catalyst on the reaction kinetics. Additionally, chronoamperometry (CA tests were conducted to study the long-term performance of the catalyst for catalyzing the methanol oxidation reaction (MOR. The binding energies of the reactants and products are compared to determine the kinetics and potential surface energy for methanol oxidation. The FESEM analysis results indicate that well-dispersed nanoscale (2–5 nm PtRu particles are formed on the MWCNTs. Finally, PtRuFeNi/MWCNT improves the reaction kinetics of anode catalysts for DMFCs and obtains a mass current of 31 A g−1 catalyst.

  11. Novel anode catalyst for direct methanol fuel cells.

    Science.gov (United States)

    Basri, S; Kamarudin, S K; Daud, W R W; Yaakob, Z; Kadhum, A A H

    2014-01-01

    PtRu catalyst is a promising anodic catalyst for direct methanol fuel cells (DMFCs) but the slow reaction kinetics reduce the performance of DMFCs. Therefore, this study attempts to improve the performance of PtRu catalysts by adding nickel (Ni) and iron (Fe). Multiwalled carbon nanotubes (MWCNTs) are used to increase the active area of the catalyst and to improve the catalyst performance. Electrochemical analysis techniques, such as energy dispersive X-ray spectrometry (EDX), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS), are used to characterize the kinetic parameters of the hybrid catalyst. Cyclic voltammetry (CV) is used to investigate the effects of adding Fe and Ni to the catalyst on the reaction kinetics. Additionally, chronoamperometry (CA) tests were conducted to study the long-term performance of the catalyst for catalyzing the methanol oxidation reaction (MOR). The binding energies of the reactants and products are compared to determine the kinetics and potential surface energy for methanol oxidation. The FESEM analysis results indicate that well-dispersed nanoscale (2-5 nm) PtRu particles are formed on the MWCNTs. Finally, PtRuFeNi/MWCNT improves the reaction kinetics of anode catalysts for DMFCs and obtains a mass current of 31 A g(-1) catalyst.

  12. Hollow Nano- and Microstructures as Catalysts.

    Science.gov (United States)

    Prieto, Gonzalo; Tüysüz, Harun; Duyckaerts, Nicolas; Knossalla, Johannes; Wang, Guang-Hui; Schüth, Ferdi

    2016-11-23

    Catalysis is at the core of almost every established and emerging chemical process and also plays a central role in the quest for novel technologies for the sustainable production and conversion of energy. Particularly since the early 2000s, a great surge of interest exists in the design and application of micro- and nanometer-sized materials with hollow interiors as solid catalysts. This review provides an updated and critical survey of the ever-expanding material architectures and applications of hollow structures in all branches of catalysis, including bio-, electro-, and photocatalysis. First, the main synthesis strategies toward hollow materials are succinctly summarized, with emphasis on the (regioselective) incorporation of various types of catalytic functionalities within their different subunits. The principles underlying the scientific and technological interest in hollow materials as solid catalysts, or catalyst carriers, are then comprehensively reviewed. Aspects covered include the stabilization of catalysts by encapsulation, the introduction of molecular sieving or stimuli-responsive "auxiliary" functionalities, as well as the single-particle, spatial compartmentalization of various catalytic functions to create multifunctional (bio)catalysts. Examples are also given on the applications which hollow structures find in the emerging fields of electro- and photocatalysis, particularly in the context of the sustainable production of chemical energy carriers. Finally, a critical perspective is provided on the plausible evolution lines for this thriving scientific field, as well as the main practical challenges relevant to the reproducible and scalable synthesis and utilization of hollow micro- and nanostructures as solid catalysts.

  13. A Numerical Model for Thermal Effects in a Microwave Irradiated Catalyst Bed

    OpenAIRE

    Lanz, Jason E.

    1998-01-01

    Electromagnetic and heat transfer analysis is used to determine possibility of selective heating of nanometer-sized, metallic catalyst particles attached to a ceramic support through microwave irradiation. This analysis is incorporated into a macroscopic heat transfer model of a packed and fluidized catalyst bed heated by a microwave field to predict thermal effects associated with selective heating of the catalyst sites. The model shows a dependence on particle size and microwave frequency...

  14. Manufacturing process of electrode catalyst layer for fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Nomoto, Hideyuki; Sakurai, Masahiro

    1988-10-17

    In order to make the electrochemical reaction of the fuel cell efficient, it is necessary that fine catalyst particles in the electrode catalyst layer and fine fluororesin particles are well dispersed and mixed uniformly and the three phase interface is big. In order to achieve this, there is a method to make an aggregate by applying a water soluble organic solvent to the dispersed system of these particles, but it has problems including a high danger of fire due to inflamation of the organic solvent. In view of this, this invention offers a method to remove the solvent of the dispersed system without using the aggregation method. In other words, this invention is composed of a process to disperse fine catalyst particles and fluororesin dispersion by adding them to the aqueous solution including a predetermined amount of interfacial active agent, a process to obtain the viscous mixed concentrate of fine catalyst particles and fine fluororesin particles by concentrating or drying the above dispersed system and then adding the water, a process to make the fine fluororesin particles fibrous and paste by kneading the above mixed concentrate, and a process to form electrode catalyst layers by rolling the above paste. 3 figures.

  15. Structure-performance relations of molybdenum- and tungsten carbide catalysts for deoxygenation

    NARCIS (Netherlands)

    Stellwagen, D.R.; Bitter, J.H.

    2015-01-01

    This work demonstrates for the first time that carbide particle size is a critical factor for the activity and stability of carbon supported tungsten- and molybdenum carbide catalysts in (hydro-)deoxygenation reactions. The stability of the catalyst was shown to increase for larger particles due to

  16. Phenol Removal by a Novel Non-Photo-Dependent Semiconductor Catalyst in a Pilot-Scaled Study: Effects of Initial Phenol Concentration, Light, and Catalyst Loading

    Directory of Open Access Journals (Sweden)

    Xiao Chen

    2014-01-01

    Full Text Available A novel non-photo-dependent semiconductor catalyst (CT was employed to degrade phenol in the present pilot-scaled study. Effect of operational parameters such as phenol initial concentration, light area, and catalyst loading on phenol degradation, was compared between CT catalyst and the conventional photocatalyst titanium dioxide. CT catalyst excelled titanium dioxide in treating and mineralizing low-level phenol, under both mild UV radiation and thunder conditions of nonphoton. The result suggested that CT catalyst could be applied in circumstances when light is not easily accessible in pollutant-carrying media (e.g., particles, cloudy water, and colored water.

  17. Methods of making textured catalysts

    Science.gov (United States)

    Werpy, Todd [West Richland, WA; Frye, Jr., John G.; Wang, Yong [Richland, WA; Zacher, Alan H [Kennewick, WA

    2010-08-17

    A textured catalyst having a hydrothermally-stable support, a metal oxide and a catalyst component is described. Methods of conducting aqueous phase reactions that are catalyzed by a textured catalyst are also described. The invention also provides methods of making textured catalysts and methods of making chemical products using a textured catalyst.

  18. Catalyst Alloys Processing

    Science.gov (United States)

    Tan, Xincai

    2014-10-01

    Catalysts are one of the key materials used for diamond formation at high pressures. Several such catalyst products have been developed and applied in China and around the world. The catalyst alloy most widely used in China is Ni70Mn25Co5 developed at Changsha Research Institute of Mining and Metallurgy. In this article, detailed techniques for manufacturing such a typical catalyst alloy will be reviewed. The characteristics of the alloy will be described. Detailed processing of the alloy will be presented, including remelting and casting, hot rolling, annealing, surface treatment, cold rolling, blanking, finishing, packaging, and waste treatment. An example use of the catalyst alloy will also be given. Industrial experience shows that for the catalyst alloy products, a vacuum induction remelt furnace can be used for remelting, a metal mold can be used for casting, hot and cold rolling can be used for forming, and acid pickling can be used for metal surface cleaning.

  19. 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....

  20. Fragmentation and disintegration of polymerizing PE particles : role of stress, brittleness and skin

    NARCIS (Netherlands)

    Keelapandal Ramamoorthy, S.N.

    2009-01-01

    Morphology control is an important issue in the field of polyolefins as well as catalyst development. New generations of supported catalysts often show complex fragmentation behaviour. A single catalyst particle (catalyst on support) is composed of many micro-grains that are packed together. During

  1. METHOD OF PURIFYING CATALYSTS

    Science.gov (United States)

    Joris, G.G.

    1958-09-01

    It has been fuund that the presence of chlorine as an impurity adversely affects the performance of finely divided platinum catalysts such as are used in the isotopic exchange process for the production of beavy water. This chlorine impurity may be removed from these catalysts by treating the catalyst at an elevated temperature with dry hydrogen and then with wet hydrogen, having a hydrogen-water vapor volume of about 8: 1. This alternate treatment by dry hydrogen and wet hydrogen is continued until the chlorine is largely removed from the catalyst.

  2. Co-Assembled Supported Catalysts: Synthesis of Nano-Structured Supported Catalysts with Hierarchic Pores through Combined Flow and Radiation Induced Co-Assembled Nano-Reactors

    Directory of Open Access Journals (Sweden)

    Galip Akay

    2016-05-01

    Full Text Available A novel generic method of silica supported catalyst system generation from a fluid state is presented. The technique is based on the combined flow and radiation (such as microwave, thermal or UV induced co-assembly of the support and catalyst precursors forming nano-reactors, followed by catalyst precursor decomposition. The transformation from the precursor to supported catalyst oxide state can be controlled from a few seconds to several minutes. The resulting nano-structured micro-porous silica supported catalyst system has a surface area approaching 300 m2/g and X-ray Diffraction (XRD-based catalyst size controlled in the range of 1–10 nm in which the catalyst structure appears as lamellar sheets sandwiched between the catalyst support. These catalyst characteristics are dependent primarily on the processing history as well as the catalyst (Fe, Co and Ni studied when the catalyst/support molar ratio is typically 0.1–2. In addition, Ca, Mn and Cu were used as co-catalysts with Fe and Co in the evaluation of the mechanism of catalyst generation. Based on extensive XRD, Scanning Electron Microscopy (SEM and Transmission Electron Microscopy (TEM studies, the micro- and nano-structure of the catalyst system were evaluated. It was found that the catalyst and silica support form extensive 0.6–2 nm thick lamellar sheets of 10–100 nm planar dimensions. In these lamellae, the alternate silica support and catalyst layer appear in the form of a bar-code structure. When these lamellae structures pack, they form the walls of a micro-porous catalyst system which typically has a density of 0.2 g/cm3. A tentative mechanism of catalyst nano-structure formation is provided based on the rheology and fluid mechanics of the catalyst/support precursor fluid as well as co-assembly nano-reactor formation during processing. In order to achieve these structures and characteristics, catalyst support must be in the form of silane coated silica nano-particles

  3. Hydroxide catalysts for lignin depolymerization

    Energy Technology Data Exchange (ETDEWEB)

    Beckham, Gregg T; Biddy, Mary J.; Kruger, Jacob S.; Chmely, Stephen C.; Sturgeon, Matthew

    2017-10-17

    Solid base catalysts and their use for the base-catalyzed depolymerization (BCD) of lignin to compounds such as aromatics are presented herein. Exemplary catalysts include layered double hydroxides (LDHs) as recyclable, heterogeneous catalysts for BCD of lignin.

  4. Hydroxide catalysts for lignin depolymerization

    Energy Technology Data Exchange (ETDEWEB)

    Beckham, Gregg T.; Biddy, Mary J.; Chmely, Stephen C.; Sturgeon, Matthew

    2017-04-25

    Solid base catalysts and their use for the base-catalyzed depolymerization (BCD) of lignin to compounds such as aromatics are presented herein. Exemplary catalysts include layered double hydroxides (LDHs) as recyclable, heterogeneous catalysts for BCD of lignin.

  5. Simple preparation of Fenton catalyst@bacterial cellulose for waste water treatment

    Science.gov (United States)

    Wibowo, Arie; Febi Indrawan, Radian; Triadhi, Untung; Hasdi Aimon, Akfiny; Iskandar, Ferry; Ardy, Husaini

    2018-02-01

    Heterogeneous fenton catalyst is one of the attractive technologies for destruction of persistent and non-biodegradable pollutant in wastewater, because it can be used in wide range of pH and recyclable. Herein, commercial bacterial celluloses (BCs) were used as an alternative support of fenton catalyst to improve their catalytic activity. Scanning Electron Microscope (SEM) observations indicated that the presence of BCs and decreasing precursor concentration might promote formation of smaller particle sizes of catalyst from 3.5 μm of bare catalyst to 0.7 μm of catalyst@BC. UV-vis measurement showed that fast degradation of dyes with half-time degradation at around 25 min was observed in sample using catalyst@BCs with precursor concentration of 0.01 M. Successful preparation of heterogeneous fenton catalyst with smaller particle size and better catalytic activity is important for their application in wastewater treatment.

  6. 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

    exposure temperatures slowdown the deactivation. K2SO4 causes a lower rate of deactivation compared to KCl. This may be related to a faster transfer of potassium from the solid KCl matrix to the catalyst, however, it cannot be ruled out toalso be caused by a significantly larger particle size of the K2SO4...

  7. A highly efficient nano-Fe3O4 encapsulated-silica particles bearing sulfonic acid groups as a solid acid catalyst for synthesis of 1,8-dioxo-octahydroxanthene derivatives

    Science.gov (United States)

    Naeimi, Hossein; Nazifi, Zahra Sadat

    2013-11-01

    The functionalization of silica-coated Fe3O4 magnetic nanoparticles (Fe3O4@SiO2) using chlorosulfonic acid were afforded sulfonic acid-functionalized magnetic Fe3O4 nanoparticles (Fe3O4@SiO2-SO3H) that can be applied as an organic-inorganic hybrid heterogeneous catalyst. The used Fe3O4 magnetic nanoparticles are 18-30 nm sized that was rapidly functionalized and can be used as catalyst in organic synthesis. The prepared nanoparticles were characterized by X-ray diffraction analysis, magnetization curve, scanning electron microscope, dynamic laser scattering, and FT-IR measurements. The resulting immobilized catalysts have been successfully used in the synthesis of 1,8-dioxo-octahydroxanthene derivatives under solvent free condition. This procedure has many advantages such as; a much milder method, a shorter reaction time, a wide range of functional group tolerance, and absence of any tedious workup or purification. Other remarkable features include the catalyst can be reused at least five times without any obvious change in its catalytic activity. This procedure also avoids hazardous reagents/solvents, and thus can be an eco-friendly alternative to the existing methods.

  8. Residual risk

    African Journals Online (AJOL)

    ing the residual risk of transmission of HIV by blood transfusion. An epidemiological approach assumed that all HIV infections detected serologically in first-time donors were pre-existing or prevalent infections, and that all infections detected in repeat blood donors were new or incident infections. During 1986 - 1987,0,012%.

  9. Catalyst for Ammonia Oxidation

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a bimetallic catalyst for ammonia oxidation, a method for producing a bimetallic catalyst for ammonia oxidation and a method for tuning the catalytic activity of a transition metal. By depositing an overlayer of less catalytic active metal onto a more catalytic...

  10. Nanostructured catalyst supports

    Science.gov (United States)

    Zhu, Yimin; Goldman, Jay L.; Qian, Baixin; Stefan, Ionel C.

    2012-10-02

    The present invention relates to SiC nanostructures, including SiC nanopowder, SiC nanowires, and composites of SiC nanopowder and nanowires, which can be used as catalyst supports in membrane electrode assemblies and in fuel cells. The present invention also relates to composite catalyst supports comprising nanopowder and one or more inorganic nanowires for a membrane electrode assembly.

  11. Catalyst for hydrocarbon conversion

    International Nuclear Information System (INIS)

    Duhaut, P.; Miquel, J.

    1975-01-01

    A description is given for a catalyst and process for hydrocarbon conversions, e.g., reforming. The catalyst contains an alumina carrier, platinum, iridium, at least one metal selected from uranium, vanadium, and gallium, and optionally halogen in the form of metal halide of one of the aforesaid components. (U.S.)

  12. Effect of preparation method on catalytic activity of Ni/ γ-Al2O3 catalysts

    International Nuclear Information System (INIS)

    Miranda Morales, Barbara

    2017-01-01

    The performance of catalysts was shown to be strongly dependent on their methods of preparation. A study to examine the relationship between catalyst preparation procedures and the structure, dispersion, activity, and selectivity of the finished catalyst is reported. 10 wt.%Ni/γ-Al 2 O 3 catalysts were prepared by incipient wetness impregnation and by wet impregnation. The catalysts were used in the conversion of glycerol in gas phase and atmospheric pressure. The selectivity and activity of the catalysts were affected by the preparation method employed. The catalysts were characterized by thermogravimetric analysis (TGA), temperature-programmed reduction (TPR), N 2 -physorption, H 2 -chemisorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR) and temperature-programmed oxidation (TPO). The Ni particle size and dispersion of the catalysts affected the selectivity to hydrogenolysis and dehydration routes, and the formation of carbon deposits was also affected. (author) [es

  13. Catalyst support effects on hydrogen spillover

    Science.gov (United States)

    Karim, Waiz; Spreafico, Clelia; Kleibert, Armin; Gobrecht, Jens; Vandevondele, Joost; Ekinci, Yasin; van Bokhoven, Jeroen A.

    2017-01-01

    Hydrogen spillover is the surface migration of activated hydrogen atoms from a metal catalyst particle, on which they are generated, onto the catalyst support. The phenomenon has been much studied and its occurrence on reducible supports such as titanium oxide is established, yet questions remain about whether hydrogen spillover can take place on nonreducible supports such as aluminium oxide. Here we use the enhanced precision of top-down nanofabrication to prepare controlled and precisely tunable model systems that allow us to quantify the efficiency and spatial extent of hydrogen spillover on both reducible and nonreducible supports. We place multiple pairs of iron oxide and platinum nanoparticles on titanium oxide and aluminium oxide supports, varying the distance between the pairs from zero to 45 nanometres with a precision of one nanometre. We then observe the extent of the reduction of the iron oxide particles by hydrogen atoms generated on the platinum using single-particle in situ X-ray absorption spectromicroscopy applied simultaneously to all particle pairs. The data, in conjunction with density functional theory calculations, reveal fast hydrogen spillover on titanium oxide that reduces remote iron oxide nanoparticles via coupled proton-electron transfer. In contrast, spillover on aluminium oxide is mediated by three-coordinated aluminium centres that also interact with water and that give rise to hydrogen mobility competing with hydrogen desorption; this results in hydrogen spillover about ten orders of magnitude slower than on titanium oxide and restricted to very short distances from the platinum particle. We anticipate that these observations will improve our understanding of hydrogen storage and catalytic reactions involving hydrogen, and that our approach to creating and probing model catalyst systems will provide opportunities for studying the origin of synergistic effects in supported catalysts that combine multiple functionalities.

  14. Characteristics of honeycomb catalysts to recover tritiated hydrogen and methane

    International Nuclear Information System (INIS)

    Tatsuhiko, Uda; Masahiro, Tanaka; Kenzo, Munakata

    2007-01-01

    Applicability of honeycomb catalysts to the tritium recovery system was examined considering tritium release accidents in the fusion plant where large volumes of air would be processed by the air cleanup system. Catalytic oxidation of isotopic hydrogen isotopes including tritium is a conventional method for the removal of tritium from air in the working space. However, the high throughput of air causes pressure drop in catalyst beds, which results in high load to the process gas pumping system. The honeycomb catalyst has an advantage in terms of pressure drop, which is estimated to be far less than that in conventional particle-packed catalyst beds. Our previous studies revealed that honeycomb catalysts made of cordierite and Al-Cr-Fe metal alloy substances have preferable oxidizing performance. It was found that the platinum-deposited cordierite catalyst shows the higher oxidation rate for hydrogen gas, and the palladium-deposited metal honeycomb catalyst shows the higher oxidation rate for methane gas. In this study, the properties of honeycomb catalysts were more systematically studied by changing experimental parameters such as noble metal content, mesh density and so forth to obtain design data base for high performance honeycomb catalysts. With regard to catalysts, the amount of noble metal deposited on the honeycomb substrates were varied from 1 g/L to 4 g/L and the mesh density of the honeycombs were changed from 260 to 400 CPSI as well. For operating conditions, the flow rate of the process gases was varied from 0.016 to 0.12 m 3 /hr, and the concentration of water vapor was changed from 0 to 1.4 %. Results of experimental study suggest that honeycomb catalysts are useful for the treatment of gases with high volumetric velocity in a fusion plant because of their low pressure drop in the catalyst reactor. The platinum catalysts were found to be suitable for oxidation of hydrogen gas, while the palladium catalysts exhibit better performance for oxidation of

  15. Catalysts, methods of making catalysts, and methods of use

    KAUST Repository

    Renard, Laetitia

    2014-03-06

    Embodiments of the present disclosure provide for catalysts, methods of making catalysts, methods of using catalysts, and the like. In an embodiment, the method of making the catalysts can be performed in a single step with a metal nanoparticle precursor and a metal oxide precursor, where a separate stabilizing agent is not needed.

  16. EXAFS characterization of supported metal catalysts in chemically dynamic environments

    International Nuclear Information System (INIS)

    Robota, H.J.

    1991-01-01

    Characterization of catalysts focuses on the identification of an active site responsible for accelerating desirable chemical reactions. The identification, characterization, and selective modification of such sites is fundamental to the development of structure-function relationships. Unfortunately, this goal is far from realized in nearly all catalysts, and particularly in catalysts comprised of small supported metal particles. X-ray absorption spectroscopy (XAS) has had a dramatic effect on our understanding of supported metal particles in their resting state. However, the performance of a catalyst can not be assessed from such simple resting state measurements. Among the factors which influence catalyst performance are the exact catalyst composition, including the support and any modifiers; particle size; catalyst finishing and pretreatment conditions; pressure, composition, and temperature of the operating environment; time. Gaining an understanding of how the structure of a catalytic site can change with such an array of variables requires that we begin to develop measurement methods which are effective under chemically dynamic conditions. Ideally, it should be possible to obtain a full X-ray absorption spectrum of each element thought to have a causal relationship with observed catalyst properties. From these spectra, we can optimally extract only a relatively limited amount of information which we must then piece together with information derived from other characterization methods and intuition to arrive at a hypothetical structure of the operating catalyst. Information about crystallinity, homogeneity, and general disorder can be obtained from the Debye-Waller factor. Finally, through analogy with known compounds, the electronic structure of the active atoms can be inferred from near edge absorption features

  17. Residual basins

    International Nuclear Information System (INIS)

    D'Elboux, C.V.; Paiva, I.B.

    1980-01-01

    Exploration for uranium carried out over a major portion of the Rio Grande do Sul Shield has revealed a number of small residual basins developed along glacially eroded channels of pre-Permian age. Mineralization of uranium occurs in two distinct sedimentary units. The lower unit consists of rhythmites overlain by a sequence of black shales, siltstones and coal seams, while the upper one is dominated by sandstones of probable fluvial origin. (Author) [pt

  18. 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

  19. Impregnation alternatives for Fe-based coal liquefaction catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, R.K.; Armstong, B.T.; Givens, E.N. [Univ. of Kentucky, Lexington, KY (United States)

    1994-12-31

    Because of the cost effective and environmentally compatible nature of Fe, attention has been directed towards improving the utilization of this metal in direct coal liquefaction. Among the several factors thought to affect catalyst activity, much of this work has focused on dispersion. Weller and Pelipetz reported the importance of catalyst dispersion, based on experiments with a wide variety of catalysts in solvent-free liquefaction studies. And in the presence of solvent, other studies have demonstrated the advantages of adding the precursor by impregnation over its addition in the form of particulates. In general, a high surface/volume ratio, along with intimate contact between the active catalyst and coal, are thought to be the controlling factors. Dispersion, as normally inferred from changes in catalyst activity, may be affected by the mode of addition, the presence of solvent, and the initial composition of the precursor (e.g., soluble organometallics); and for coal-impregnated catalyst precursors, the choice of impregnation solvent and impregnation conditions. A variety of innovative strategies have been developed to introduce catalyst precursors to the liquefaction reaction while seeking to maintain particle size and distribution. These have included the use of emulsions and colloids, direct addition of ultra-fine particles to the slurry`s addition of oil soluble organometallics and carbonyls, ion exchange and impregnating the coal. This paper describes the results of liquefaction experiments carried out with the impregnation of subbituminous coal with iron.

  20. Stability and resistance of nickel catalysts for hydrodeoxygenation

    DEFF Research Database (Denmark)

    Mortensen, Peter Mølgaard; Gardini, Diego; de Carvalho, Hudson W. P.

    2014-01-01

    deactivation with complete loss of activity due to the formation of nickel sulfide. Exposing Ni/ZrO2 to chlorine-containing compounds (at a concentration of 0.05 wt% Cl) on-stream led to a steady decrease in activity over 40 h of exposure. Removal of the chlorine species from the feed led to the regaining...... of activity. Analysis of the spent catalyst revealed that the adsorption of chlorine on the catalyst was completely reversible, but chlorine had caused sintering of nickel particles. In two experiments, potassium, as either KCl or KNO3, was impregnated on the catalyst prior to testing. In both cases...

  1. Interfacial charge distributions in carbon-supported palladium catalysts

    DEFF Research Database (Denmark)

    Rao, Radhika G.; Blume, Raoul; Hansen, Thomas Willum

    2017-01-01

    trends between the charge distribution at the palladium-carbon interface and the metal's selectivity for hydrogenation of multifunctional chemicals. These electronic effects are strong enough to affect the performance of large (~5 nm) Pd particles. Our results also demonstrate how simple thermal...... treatments can be used to tune the interfacial charge distribution, hereby providing a strategy to rationally design carbon-supported catalysts.Control over charge transfer in carbon-supported metal nanoparticles is essential for designing new catalysts. Here, the authors show that thermal treatments...... effectively tune the interfacial charge distribution in carbon-supported palladium catalysts with consequential changes in hydrogenation performance....

  2. Colloid Science of Metal Nanoparticle Catalysts in 2D and 3D Structures. Challenges of Nucleation, Growth, Composition, Particle Shape, Size Control and their Influence on Activity and Selectivity

    Energy Technology Data Exchange (ETDEWEB)

    Somorjai, Gabor A.; Park, Jeong Y.

    2008-02-13

    Recent breakthroughs in synthesis in nanosciences have achieved control of size and shapes of nanoparticles that are relevant for catalyst design. In this article, we review the advance of synthesis of nanoparticles, fabrication of two and three dimensional model catalyst system, characterization, and studies of activity and selectivity. The ability to synthesize monodispersed platinum and rhodium nanoparticles in the 1-10 nm range permitted us to study the influence of composition, structure, and dynamic properties of monodispersed metal nanoparticle on chemical reactivity and selectivity. We review the importance of size and shape of nanoparticles to determine the reaction selectivity in multi-path reactions. The influence of metal-support interaction has been studied by probing the hot electron flows through the metal-oxide interface in catalytic nanodiodes. Novel designs of nanoparticle catalytic systems are discussed.

  3. Study of spent hydrorefining catalysts

    International Nuclear Information System (INIS)

    Gellerman, M.M.; Aliev, R.R.; Sidel'kovskaya, V.G.

    1993-01-01

    Aluminonickelmolybdenum catalysts for diesel fuel hydrorefining have been studied by DTA, XSPS, and diffuse reflection spectroscopy. Chemical and phase states of molybdenum compounds in samples of fresh catalyst, regenerated one after one year operation, and clogged with coke catalyst after five year operation, are determined. Chemical reactions and crystal-phase transformations of the molybdenum compounds during catalyst deactivation and regeneration are discussed

  4. Catalysts for Environmental Remediation

    DEFF Research Database (Denmark)

    Abrams, B. L.; Vesborg, Peter Christian Kjærgaard

    2013-01-01

    on titania (V2O5-WO3/TiO2) as the example catalyst. The main photocatalysts examined for mineralization of organic compounds were TiO2 and MoS2. It is important to obtain insight into the catalyst structure-to-activity relationship in order to understand and locate the active site(s). In this chapter......The properties of catalysts used in environmental remediation are described here through specific examples in heterogeneous catalysis and photocatalysis. In the area of heterogeneous catalysis, selective catalytic reduction (SCR) of NOx was used as an example reaction with vanadia and tungsta...

  5. Titanium Dioxide as a Catalyst Support in Heterogeneous Catalysis

    Science.gov (United States)

    Bagheri, Samira; Muhd Julkapli, Nurhidayatullaili; Bee Abd Hamid, Sharifah

    2014-01-01

    The lack of stability is a challenge for most heterogeneous catalysts. During operations, the agglomeration of particles may block the active sites of the catalyst, which is believed to contribute to its instability. Recently, titanium oxide (TiO2) was introduced as an alternative support material for heterogeneous catalyst due to the effect of its high surface area stabilizing the catalysts in its mesoporous structure. TiO2 supported metal catalysts have attracted interest due to TiO2 nanoparticles high activity for various reduction and oxidation reactions at low pressures and temperatures. Furthermore, TiO2 was found to be a good metal oxide catalyst support due to the strong metal support interaction, chemical stability, and acid-base property. The aforementioned properties make heterogeneous TiO2 supported catalysts show a high potential in photocatalyst-related applications, electrodes for wet solar cells, synthesis of fine chemicals, and others. This review focuses on TiO2 as a support material for heterogeneous catalysts and its potential applications. PMID:25383380

  6. Titanium Dioxide as a Catalyst Support in Heterogeneous Catalysis

    Directory of Open Access Journals (Sweden)

    Samira Bagheri

    2014-01-01

    Full Text Available The lack of stability is a challenge for most heterogeneous catalysts. During operations, the agglomeration of particles may block the active sites of the catalyst, which is believed to contribute to its instability. Recently, titanium oxide (TiO2 was introduced as an alternative support material for heterogeneous catalyst due to the effect of its high surface area stabilizing the catalysts in its mesoporous structure. TiO2 supported metal catalysts have attracted interest due to TiO2 nanoparticles high activity for various reduction and oxidation reactions at low pressures and temperatures. Furthermore, TiO2 was found to be a good metal oxide catalyst support due to the strong metal support interaction, chemical stability, and acid-base property. The aforementioned properties make heterogeneous TiO2 supported catalysts show a high potential in photocatalyst-related applications, electrodes for wet solar cells, synthesis of fine chemicals, and others. This review focuses on TiO2 as a support material for heterogeneous catalysts and its potential applications.

  7. Scalable synthesis of palladium nanoparticle catalysts by atomic layer deposition

    International Nuclear Information System (INIS)

    Liang Xinhua; Lyon, Lauren B.; Jiang Yingbing; Weimer, Alan W.

    2012-01-01

    Atomic layer deposition (ALD) was used to produce Pd/Al 2 O 3 catalysts using sequential exposures of Pd(II) hexafluoroacetylacetonate and formalin at 200 °C in a fluidized bed reactor. The ALD-prepared Pd/alumina catalysts were characterized by various methods including hydrogen chemisorption, XPS, and TEM, and compared with a commercially available 1 wt% Pd/alumina catalyst, which was also characterized. The content of Pd on alumina support and the size of Pd nanoparticles can be controlled by the number of ALD-coating cycles and the dose time of the Pd precursor. One layer of organic component from the Pd precursor remained on the Pd particle surface. The ALD 0.9 wt% Pd/alumina had greater active metal surface area and percent metal dispersion than the commercial 1 wt% Pd/alumina catalyst. The ALD and commercial catalysts were subjected to catalytic testing to determine their relative activities for glucose oxidation to gluconic acid in aqueous solution. The ALD 0.9 wt% Pd/alumina catalyst had comparable activity as compared to the commercial 1 wt% Pd catalyst. No noticeable amount of Pd leaching was observed for the ALD-prepared catalysts during the vigorously stirred reaction.

  8. Catalyst for microelectromechanical systems microreactors

    Science.gov (United States)

    Morse, Jeffrey D [Martinez, CA; Sopchak, David A [Livermore, CA; Upadhye, Ravindra S [Pleasanton, CA; Reynolds, John G [San Ramon, CA; Satcher, Joseph H [Patterson, CA; Gash, Alex E [Brentwood, CA

    2010-06-29

    A microreactor comprising a silicon wafer, a multiplicity of microchannels in the silicon wafer, and a catalyst coating the microchannels. In one embodiment the catalyst coating the microchannels comprises a nanostructured material. In another embodiment the catalyst coating the microchannels comprises an aerogel. In another embodiment the catalyst coating the microchannels comprises a solgel. In another embodiment the catalyst coating the microchannels comprises carbon nanotubes.

  9. TOPICAL REVIEW: Nanostructured catalysts in fuel cells

    Science.gov (United States)

    Zhong, Chuan-Jian; Luo, Jin; Fang, Bin; Wanjala, Bridgid N.; Njoki, Peter N.; Loukrakpam, Rameshwori; Yin, Jun

    2010-02-01

    One of the most important challenges for the ultimate commercialization of fuel cells is the preparation of active, robust, and low-cost catalysts. This review highlights some findings of our investigations in the last few years in developing advanced approaches to nanostructured catalysts that address this challenge. Emphasis is placed on nanoengineering-based fabrication, processing, and characterization of multimetallic nanoparticles with controllable size (1-10 nm), shape, composition (e.g. MlnM2100-n, M1nM2mM3100-n-m, M1@M2, where M (1 or 2) = Pt, Co, Ni, V, Fe, Cu, Pd, W, Ag, Au etc) and morphology (e.g. alloy, core@shell etc). In addition to an overview of the fundamental issues and the recent progress in fuel cell catalysts, results from evaluations of the electrocatalytic performance of nanoengineered catalysts in fuel cell reactions are discussed. This approach differs from other traditional approaches to the preparation of supported catalysts in the ability to control the particle size, composition, phase, and surface properties. An understanding of how the nanoscale properties of the multimetallic nanoparticles differ from their bulk-scale counterparts, and how the interaction between the nanoparticles and the support materials relates to the size sintering or evolution in the thermal activation process, is also discussed. The fact that the bimetallic gold-platinum nanoparticle system displays a single-phase character different from the miscibility gap known for its bulk-scale counterpart serves as an important indication of the nanoscale manipulation of the structural properties, which is useful for refining the design and preparation of the bimetallic catalysts. The insight gained from probing how nanoparticle-nanoparticle and nanoparticle-substrate interactions relate to the size evolution in the activation process of nanoparticles on planar substrates serves as an important guiding principle in the control of nanoparticle sintering on different

  10. Down-flow moving-bed gasifier with catalyst recycle

    Science.gov (United States)

    Halow, John S.

    1999-01-01

    The gasification of coal and other carbonaceous materials by an endothermic gasification reaction is achieved in the presence of a catalyst in a down-flow, moving-bed gasifier. Catalyst is removed along with ash from the gasifier and is then sufficiently heated in a riser/burner by the combustion of residual carbon in the ash to volatilize the catalyst. This volatilized catalyst is returned to the gasifier where it uniformly contacts and condenses on the carbonaceous material. Also, the hot gaseous combustion products resulting from the combustion of the carbon in the ash along with excess air are introduced into the gasifier for providing heat energy used in the endothermic reaction.

  11. Catalysts and method

    Science.gov (United States)

    Taylor, Charles E.; Noceti, Richard P.

    1991-01-01

    An improved catlayst and method for the oxyhydrochlorination of methane is disclosed. The catalyst includes a pyrogenic porous support on which is layered as active material, cobalt chloride in major proportion, and minor proportions of an alkali metal chloride and of a rare earth chloride. On contact of the catalyst with a gas flow of methane, HC1 and oxygen, more than 60% of the methane is converted and of that converted more than 40% occurs as monochloromethane. Advantageously, the monochloromethane can be used to produce gasoline boiling range hydrocarbons with the recycle of HCl for further reaction. This catalyst is also of value for the production of formic acid as are analogous catalysts with lead, silver or nickel chlorides substituted for the cobalt chloride.

  12. Epoxidation catalyst and process

    Science.gov (United States)

    Linic, Suljo; Christopher, Phillip

    2010-10-26

    Disclosed herein is a catalytic method of converting alkenes to epoxides. This method generally includes reacting alkenes with oxygen in the presence of a specific silver catalyst under conditions suitable to produce a yield of the epoxides. The specific silver catalyst is a silver nanocrystal having a plurality of surface planes, a substantial portion of which is defined by Miller indices of (100). The reaction is performed by charging a suitable reactor with this silver catalyst and then feeding the reactants to the reactor under conditions to carry out the reaction. The reaction may be performed in batch, or as a continuous process that employs a recycle of any unreacted alkenes. The specific silver catalyst has unexpectedly high selectivity for epoxide products. Consequently, this general method (and its various embodiments) will result in extraordinarily high epoxide yields heretofore unattainable.

  13. Latent olefin metathesis catalysts

    OpenAIRE

    Monsaert, Stijn; Lozano Vila, Ana; Drozdzak, Renata; Van Der Voort, Pascal; Verpoort, Francis

    2009-01-01

    Olefin metathesis is a versatile synthetic tool for the redistribution of alkylidene fragments at carbon-carbon double bonds. This field, and more specifically the development of task-specific, latent catalysts, attracts emerging industrial and academic interest. This tutorial review aims to provide the reader with a concise overview of early breakthroughs and recent key developments in the endeavor to develop latent olefin metathesis catalysts, and to illustrate their use by prominent exampl...

  14. Plasmatron-catalyst system

    Science.gov (United States)

    Bromberg, Leslie; Cohn, Daniel R.; Rabinovich, Alexander; Alexeev, Nikolai

    2007-10-09

    A plasmatron-catalyst system. The system generates hydrogen-rich gas and comprises a plasmatron and at least one catalyst for receiving an output from the plasmatron to produce hydrogen-rich gas. In a preferred embodiment, the plasmatron receives as an input air, fuel and water/steam for use in the reforming process. The system increases the hydrogen yield and decreases the amount of carbon monoxide.

  15. Hydrothermal catalytic gasification of fermentation residues from a biogas plant

    International Nuclear Information System (INIS)

    Zöhrer, Hemma; Vogel, Frédéric

    2013-01-01

    Biogas plants, increasing in number, produce a stream of fermentation residue with high organic content, providing an energy source which is by now mostly unused. We tested this biomass as a potential feedstock for catalytic gasification in supercritical water (T ≥ 374 °C, p ≥ 22 MPa) for methane production using a batch reactor system. The coke formation tendency during the heat-up phase was evaluated as well as the cleavage of biomass-bound sulfur with respect to its removal from the process as a salt. We found that sulfur is not sufficiently released from the biomass during heating up to a temperature of 410 °C. Addition of alkali salts improved the liquefaction of fermentation residues with a low content of minerals, probably by buffering the pH. We found a deactivation of the carbon-supported ruthenium catalyst at low catalyst-to-biomass loadings, which we attribute to sulfur poisoning and fouling in accordance with the composition of the fermentation residue. A temperature of 400 °C was found to maximize the methane yield. A residence time dependent biomass to catalyst ratio of 0.45 g g −1 h −1 was found to result in nearly full conversion with the Ru/C catalyst. A Ru/ZrO 2 catalyst, tested under similar conditions, was less active. -- Highlights: ► Fermentation residue of a biogas plant could be successfully liquefied with a low rate of coke formation. ► Liquefaction resulted in an incomplete removal of biomass-bound sulfur. ► Low catalyst loadings result in incomplete conversion, implicating catalyst deactivation. ► At 400 °C the observed conversion to methane was highest. ► A residence time dependent biomass to catalyst ratio of 0.45 g g −1 h −1 was determined to yield nearly complete conversion

  16. Catalyst system comprising a first catalyst system tethered to a supported catalyst

    Science.gov (United States)

    Angelici, Robert J.; Gao, Hanrong

    1998-08-04

    The present invention provides new catalyst formats which comprise a supported catalyst tethered to a second and different catalyst by a suitable tethering ligand. A preferred system comprises a heterogeneous supported metal catalyst tethered to a homogeneous catalyst. This combination of homogeneous and heterogeneous catalysts has a sufficient lifetime and unusually high catalytic activity in arene hydrogenations, and potentially many other reactions as well, including, but not limited to hydroformylation, hydrosilation, olefin oxidation, isomerization, hydrocyanation, olefin metathesis, olefin polymerization, carbonylation, enantioselective catalysis and photoduplication. These catalysts are easily separated from the products, and can be reused repeatedly, making these systems very economical.

  17. Characterization of coke, or carbonaceous matter, formed on CoMo catalysts used in hydrodesulfurization unit in oil refinery

    Science.gov (United States)

    Kimura, Nobuharu; Iwanami, Yoshimu; Koide, Ryutaro; Kudo, Reiko

    2017-06-01

    When a mixture of light gas oil (LGO) and light cycle oil is fed into an oil refinery’s hydrodesulfurization (HDS) unit to produce diesel fuel, the catalyst in the HDS unit is rapidly deactivated. By contrast, when the feed is LGO mixed with residue desulfurization gas oil, the catalyst is deactivated slowly. Hoping to understand why, the authors focused on the coke formed on the catalysts during the HDS reaction. The result of a comprehensive analysis of the coke suggested that the ways coke formed and grew on the catalysts may differ depending on the feeds used, which in turn could affect the deactivation behaviors of the catalysts.

  18. Effect of catalyst pretreatment on the olefin metathesis catalyzed by alumina-supported (9%) rhenium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, J.C.

    1979-01-01

    A kinetic model was developed to express the time-on-stream profile of the activity during catalyst break-in and deactivation. The catalyst surface is in geometric and energetic heterogeneity. Partial catalyst reduction is a prerequisite step for olefin metathesis. The metathesis activity may be affected by the coordination number and the type of ligands associated with the sites on the catalyst. The deactivation is proposed due to deposition of residues on the active sites, and to sintering, etc. A dispersion pretreatment increased activity. Oxygen is an activator. The hydrogen reduction at 500/sup 0/C causes partial but permanent loss of activity.

  19. Polyelectrolyte Brush-Grafted Polydopamine-Based Catalysts with Enhanced Catalytic Activity and Stability.

    Science.gov (United States)

    Kaang, Byung Kwon; Han, Nara; Lee, Ha-Jin; Choi, Won San

    2018-01-10

    Three types of surface treatments, namely, polyethyleneimine (PEI) coating, short PEI (S-PEI) grafting, and long PEI (L-PEI) grafting, were performed on polydopamine (Pdop)-based catalysts to enhance their catalytic activity and stability. Brush-grafted catalysts were prepared by the stepwise synthesis of Au and short (or long) PEI brushes on Pdop particles (PdopP/Au/S- or L-PEI grafting). PEI-coated Pdop-based catalysts (PdopP/Au/PEI coating) were also prepared as non-brush-grafted catalysts. Among the surface-treated PdopP/Au catalysts, the brush-grafted catalysts (S-PEI and L-PEI grafting) exhibited excellent and stable catalytic performance because the brush grafting enabled the protection of the catalysts against harsh conditions, effective transfer of reactants to the catalysts, and confinement of reactants around the catalysts. The brush-grafted catalysts could also more effectively decompose larger dyes than the non-brush-grafted catalysts. The process-to-effectiveness of PEI coating is the best because the release of Pdop from PdopP/Au was moderately inhibited by the presence of only one layer of PEI coating on the PdopP/Au. Thus, this approach could be an alternative method to enhance the stability of PdopP/Au catalysts.

  20. Alumina/silica aerogel with zinc chloride as an alkylation catalyst

    Directory of Open Access Journals (Sweden)

    DEJAN U. SKALA

    2001-10-01

    Full Text Available The alumina/silica with zinc chloride aerogel alkylation catalyst was obtained using a one step sol-gel synthesis, and subsequent drying with supercritical carbon dioxide. The aerogel catalyst activity was found to be higher compared to the corresponding xerogel catalyst, as a result of the higher aerogel surface area, total pore volume and favourable pore size distribution. Mixed Al–O–Si bonds were present in both gel catalyst types. Activation by thermal treatment in air was needed prior to catalytic alkylation, due to the presence of residual organic groups on the aerogel surface. The optimal activation temperature was found to be in the range 185–225°C, while higher temperatures resulted in the removal of zinc chloride from the surface of the aerogel catalyst with a consequential decrease in the catalytic activity. On varying the zinc chloride content, the catalytic activity of the aerogel catalyst exhibited a maximum. High zinc chloride contents decreased the catalytic activity of the aerogel catalyst as the result of the pores of the catalyst being plugged with this compound, and the separation of the alumina/silica support into Al-rich and Si-rich phases. The surface area, total pore volume, pore size distribution and zinc chloride content had a similar influence on the activity of the aerogel catalyst as was the case of xerogel catalyst and supported zinc chloride catalysts.

  1. Recent Progress on Transition Metal Catalyst Separation and Recycling in ATRP.

    Science.gov (United States)

    Ding, Mingqiang; Jiang, Xiaowu; Zhang, Lifen; Cheng, Zhenping; Zhu, Xiulin

    2015-10-01

    Atom transfer radical polymerization (ATRP) is a versatile and robust tool to synthesize a wide spectrum of monomers with various designable structures. However, it usually needs large amounts of transition metal as the catalyst to mediate the equilibrium between the dormant and propagating species. Unfortunately, the catalyst residue may contaminate or color the resultant polymers, which limits its application, especially in biomedical and electronic materials. How to efficiently and economically remove or reduce the catalyst residue from its products is a challenging and encouraging task. Herein, recent advances in catalyst separation and recycling are highlighted with a focus on (1) highly active ppm level transition metal or metal free catalyzed ATRP; (2) post-purification method; (3) various soluble, insoluble, immobilized/soluble, and reversible supported catalyst systems; and (4) liquid-liquid biphasic catalyzed systems, especially thermo-regulated catalysis systems. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. RESIDUAL RISK ASSESSMENTS - RESIDUAL RISK ...

    Science.gov (United States)

    This source category previously subjected to a technology-based standard will be examined to determine if health or ecological risks are significant enough to warrant further regulation for Coke Ovens. These assesments utilize existing models and data bases to examine the multi-media and multi-pollutant impacts of air toxics emissions on human health and the environment. Details on the assessment process and methodologies can be found in EPA's Residual Risk Report to Congress issued in March of 1999 (see web site). To assess the health risks imposed by air toxics emissions from Coke Ovens to determine if control technology standards previously established are adequately protecting public health.

  3. Ferromagnetic resonance of cobalt nanoparticles used as a catalyst for the carbon nanotubes synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Duraia, El-Shazly M. [Suez Canal University, Faculty of Science, Physics Department, Ismailia (Egypt); Al-Farabi Kazakh National University, Almaty (Kazakhstan); Institute of Physics and Technology, Almaty (Kazakhstan)], E-mail: duraia_physics@yahoo.com; Abdullin, Kh.A. [Institute of Physics and Technology, Almaty (Kazakhstan)

    2009-12-15

    Catalyst is considered to be the most crucial parameter for the growth of carbon nanotubes. In this work we study the ferromagnetic resonance (FMR) spectra of the catalyst nanoclusters. Moreover we report for the first time the angle FMR studies of catalyst particles with and without CNT layer. The dependencies of the FMR spectra, X-ray diffraction (XRD) patterns, Raman spectra and morphology of the CNT layers on the growth conditions are discussed.

  4. Iron on mixed zirconia-titania substrate F-T catalyst

    International Nuclear Information System (INIS)

    Dyer, P.N.; Nordquist, A.F.; Pierantozzi, R.

    1988-01-01

    This patent deals with a Fischer-Tropsch catalyst comprising iron co-deposited with or deposited on particles comprising a mixture of zirconia and titania, preferably formed by co-precipitation of compounds convertible to zirconia and titania, such as zirconium and titanium alkoxide. The invention also comprises the method of making this catalyst and an improved Fischer-Tropsch reaction process in which the catalyst is utilized

  5. Iron on mixed zirconia-titania substrate Fischer-Tropsch catalyst and method of making same

    Science.gov (United States)

    Dyer, Paul N.; Nordquist, Andrew F.; Pierantozzi, Ronald

    1986-01-01

    A Fischer-Tropsch catalyst comprising iron co-deposited with or deposited on particles comprising a mixture of zirconia and titania, preferably formed by co-precipitation of compounds convertible to zirconia and titania, such as zirconium and titanium alkoxide. The invention also comprises the method of making this catalyst and an improved Fischer-Tropsch reaction process in which the catalyst is utilized.

  6. Catalysts to reduce NO.sub.x in an exhaust gas stream and methods of preparation

    Science.gov (United States)

    Koermer, Gerald S [Basking Ridge, NJ; Moini, Ahmad [Princeton, NJ; Furbeck, Howard [Hamilton, NJ; Castellano, Christopher R [Ringoes, NJ

    2012-05-08

    Catalysts, systems and methods are described to reduce NO.sub.x emissions of an internal combustion engine. In one embodiment, an emissions treatment system for an exhaust stream is provided having a catalyst comprising silver on a particulate alumina support, the silver having a diameter of less than about 20 nm. Methods of manufacturing catalysts are described in which ionic silver is impregnated on particulate hydroxylated alumina particles.

  7. Catalysts to reduce NO.sub.x in an exhaust gas stream and methods of preparation

    Science.gov (United States)

    Castellano, Christopher R [Ringoes, NJ; Moini, Ahmad [Princeton, NJ; Koermer, Gerald S [Basking Ridge, NJ; Furbeck, Howard [Hamilton, NJ; Schmieg, Steven J [Troy, MI; Blint, Richard J [Shelby Township, MI

    2011-05-17

    Catalysts, systems and methods are described to reduce NO.sub.x emissions of an internal combustion engine. In one embodiment, an emissions treatment system for an exhaust stream is provided having a catalyst comprising silver and a platinum group metal on a particulate alumina support, the atomic fraction of the platinum group metal being less than or equal to about 0.25. Methods of manufacturing catalysts are described in which silver is impregnated on alumina particles.

  8. Magnetic and dendritic catalysts.

    Science.gov (United States)

    Wang, Dong; Deraedt, Christophe; Ruiz, Jaime; Astruc, Didier

    2015-07-21

    The recovery and reuse of catalysts is a major challenge in the development of sustainable chemical processes. Two methods at the frontier between homogeneous and heterogeneous catalysis have recently emerged for addressing this problem: loading the catalyst onto a dendrimer or onto a magnetic nanoparticle. In this Account, we describe representative examples of these two methods, primarily from our research group, and compare them. We then describe new chemistry that combines the benefits of these two methods of catalysis. Classic dendritic catalysis has involved either attaching the catalyst covalently at the branch termini or within the dendrimer core. We have used chelating pyridyltriazole ligands to insolubilize catalysts at the termini of dendrimers, providing an efficient, recyclable heterogeneous catalysts. With the addition of dendritic unimolecular micelles olefin metathesis reactions catalyzed by commercial Grubbs-type ruthenium-benzylidene complexes in water required unusually low amounts of catalyst. When such dendritic micelles include intradendritic ligands, both the micellar effect and ligand acceleration promote faster catalysis in water. With these types of catalysts, we could carry out azide alkyne cycloaddition ("click") chemistry with only ppm amounts of CuSO4·5H2O and sodium ascorbate under ambient conditions. Alternatively we can attach catalysts to the surface of superparamagnetic iron oxide nanoparticles (SPIONs), essentially magnetite (Fe3O4) or maghemite (γ-Fe2O3), offering the opportunity to recover the catalysts using magnets. Taking advantage of the merits of both of these strategies, we and others have developed a new generation of recyclable catalysts: dendritic magnetically recoverable catalysts. In particular, some of our catalysts with a γ-Fe2O3@SiO2 core and 1,2,3-triazole tethers and loaded with Pd nanoparticles generate strong positive dendritic effects with respect to ligand loading, catalyst loading, catalytic activity and

  9. Design of slurry bubble column reactors: novel technique for optimum catalyst size selection contractual origin of the invention

    Science.gov (United States)

    Gamwo, Isaac K [Murrysville, PA; Gidaspow, Dimitri [Northbrook, IL; Jung, Jonghwun [Naperville, IL

    2009-11-17

    A method for determining optimum catalyst particle size for a gas-solid, liquid-solid, or gas-liquid-solid fluidized bed reactor such as a slurry bubble column reactor (SBCR) for converting synthesis gas into liquid fuels considers the complete granular temperature balance based on the kinetic theory of granular flow, the effect of a volumetric mass transfer coefficient between the liquid and the gas, and the water gas shift reaction. The granular temperature of the catalyst particles representing the kinetic energy of the catalyst particles is measured and the volumetric mass transfer coefficient between the gas and liquid phases is calculated using the granular temperature. Catalyst particle size is varied from 20 .mu.m to 120 .mu.m and a maximum mass transfer coefficient corresponding to optimum liquid hydrocarbon fuel production is determined. Optimum catalyst particle size for maximum methanol production in a SBCR was determined to be in the range of 60-70 .mu.m.

  10. Residual nilpotence and residual solubility of groups

    International Nuclear Information System (INIS)

    Mikhailov, R V

    2005-01-01

    The properties of the residual nilpotence and the residual solubility of groups are studied. The main objects under investigation are the class of residually nilpotent groups such that each central extension of these groups is also residually nilpotent and the class of residually soluble groups such that each Abelian extension of these groups is residually soluble. Various examples of groups not belonging to these classes are constructed by homological methods and methods of the theory of modules over group rings. Several applications of the theory under consideration are presented and problems concerning the residual nilpotence of one-relator groups are considered.

  11. Investigation and development of heavy oil upgrading catalysts. 3

    Energy Technology Data Exchange (ETDEWEB)

    Lee, D.K.; Lee, I.C.; Yoon, W.L.; Lee, H.T.; Chung, H.; Hwang, Y.J.; Park, S.H. [Korea Inst. of Energy Research, Taejon (Korea, Republic of)

    1995-12-01

    This study aimed at the domestic development of HDS catalysts which are most fundamental and wide-used in the petroleum refinery. In this year, some experimental works were conducted for developing the effective utilization technology of the novel dispersed-catalysts in the hydro-desulfurization of heavy oils, and improving the reaction performance of alumina-supported Mo-based hydro-treating catalysts conventionally used in most of refineries. First, it was experimentally proved that the dispersed catalysts of Co-Mo could be employed for the hydro-desulfurization of a heavy atmospheric residual oil excluding the catalyst deactivation. The utilization of a carbon-expanded reactor in combination with this dispersed catalyst system exhibited an enhanced reaction performance and provided an efficient way for the separation and recovery of the dispersed catalytic component from oils. Second, the tungsten-incorporated WCoMo/{gamma}-Al{sub 2}O{sub 3} catalyst revealed the improved catalytic performance in the various hydro-treating reactions and in the initial deactivation rates for the high pressure hydro-treatment of a heavy oil as compared with the commercial CoMo/{gamma}-Al{sub 2}O{sub 3} catalyst. This new experimental finding for the promoting role of the monomeric WO{sub 3} species in CoMo/{gamma}-Al{sub 2}O{sub 3} catalyst may be generally applicable to the Mo-based alumina-sulfide phase, higher catalytic activity, and more extended service life. (author). 101 refs., 33 figs., 18 tabs.

  12. Catalyst component interactions in nickel/alumina catalyst

    Directory of Open Access Journals (Sweden)

    Kiš Erne E.

    2007-01-01

    Full Text Available The influence of nickel loading (5; 10; 20 wt% Ni, temperature of heat treatment (400; 700; 1100°C and way of catalyst preparation on the catalyst component interactions (CCI in the impregnated, mechanical powder mixed and co-precipitated catalyst was investigated. For sample characterization, low temperature nitrogen adsorption (LTNA and X-ray diffraction (XRD were applied. Significant differences were revealed, concerning CCI in dependence of nickel loading, temperature of heat treatment and way of catalyst preparation. The obtained results show that the support metal oxide interactions (SMI in impregnated and co-precipitated catalysts are more intensive than in the mechanical powder mixed catalyst. The degree and intensity of CCI is expressed by the ratio of real and theoretical surface area of the catalyst. This ratio can be used for a quantitative estimation of CCI and it is generally applicable to all types of heterogeneous catalysts.

  13. Supported Catalysts Useful in Ring-Closing Metathesis, Cross Metathesis, and Ring-Opening Metathesis Polymerization

    Directory of Open Access Journals (Sweden)

    Jakkrit Suriboot

    2016-04-01

    Full Text Available Ruthenium and molybdenum catalysts are widely used in synthesis of both small molecules and macromolecules. While major developments have led to new increasingly active catalysts that have high functional group compatibility and stereoselectivity, catalyst/product separation, catalyst recycling, and/or catalyst residue/product separation remain an issue in some applications of these catalysts. This review highlights some of the history of efforts to address these problems, first discussing the problem in the context of reactions like ring-closing metathesis and cross metathesis catalysis used in the synthesis of low molecular weight compounds. It then discusses in more detail progress in dealing with these issues in ring opening metathesis polymerization chemistry. Such approaches depend on a biphasic solid/liquid or liquid separation and can use either always biphasic or sometimes biphasic systems and approaches to this problem using insoluble inorganic supports, insoluble crosslinked polymeric organic supports, soluble polymeric supports, ionic liquids and fluorous phases are discussed.

  14. Mesoporous Molecular Sieves Based Catalysts for Olefin Metathesis and Metathesis Polymerization

    Science.gov (United States)

    Balcar, Hynek; Čejka, Jiří

    Heterogeneous catalysts for olefin metathesis using different types of (i) siliceous mesoporous molecular sieves, and (ii) organized mesoporous alumina as supports are reported. The catalysts were prepared either by spreading of transition metal oxidic phase on the support surface or by immobilizing transition metal compounds (mostly organometallic) on the support. The activity of these catalysts in various types of metathesis reactions (i.e. alkene and diene metathesis, metathesis of unsaturated esters and ethers, RCM, ROMP and metathesis polymerization of alkynes) was described. The main advantages of these catalysts consist generally in their high activity and selectivity, easy separation of catalysts from reaction products and the preparation of products free of catalyst residue. The examples of pore size influence on the selectivity in metathesis reactions are also given.

  15. Cobalt supported on carbon nanofibers as catalysts for the Fischer-Tropsch synthesis

    NARCIS (Netherlands)

    Bezemer, G.L.

    2006-01-01

    The Fischer-Tropsch (FT) process converts synthesis gas (H2/CO) over a heterogeneous catalyst into hydrocarbons. Generally, cobalt catalysts supported on oxidic carriers are used for the FT process, however it appears to be difficult to obtain and maintain fully reduced cobalt particles. To overcome

  16. Observation of ionomer in catalyst ink of polymer electrolyte fuel cell using cryogenic transmission electron microscopy

    International Nuclear Information System (INIS)

    Takahashi, Shinichi; Shimanuki, Junichi; Mashio, Tetsuya; Ohma, Atsushi; Tohma, Hajime; Ishihara, Ayumi; Ito, Yoshiko; Nishino, Yuri; Miyazawa, Atsuo

    2017-01-01

    Optimizing the catalyst layer structure is one of the key issues for improving performance despite lower platinum loading. The catalyst ink, consisting of platinum-loaded carbon particles and ionomer dispersed in an aqueous solvent, is a key factor for controlling the structure of the catalyst layer because the catalyst layer is prepared in a wet coating process. For that purpose, we visualized the nanostructure of the ionomer in the catalyst ink by cryogenic electron microscopy, especially cryogenic transmission electron microscopy (cryo-TEM). By cryo-TEM, it was revealed that ionomer molecules formed rod-like aggregates macro-homogeneously in the solvent, and a similar morphology was observed in a carbon-particle-containing solvent. In contrast, ionomer aggregates in the catalyst ink containing platinum nanoparticles loaded on carbon particles were denser in the vicinity of the platinum-loaded carbon particles. That can be attributed to strong interaction between platinum nanoparticles and sulfonic acid groups in the ionomer. It also implies that a good understanding of ionomer morphology in the catalyst ink can play an important role in controlling the catalyst layer microstructure for reducing platinum loading.

  17. ZnO nanoparticle as catalyst for efficient green one-pot synthesis of ...

    Indian Academy of Sciences (India)

    Green chemistry protocols with the reusability of the nano particle as catalyst in the synthesis of coumarins is described. The zinc oxide (ZnO) nanoparticles functions as highly effective catalyst for the reactions of various -hydroxy benzaldehydes with 1,3-dicarbonyl compounds under microwave and thermal conditions to ...

  18. Supported organoiridium catalysts for alkane dehydrogenation

    Science.gov (United States)

    Baker, R. Thomas; Sattelberger, Alfred P.; Li, Hongbo

    2013-09-03

    Solid supported organoiridium catalysts, a process for preparing such solid supported organoiridium catalysts, and the use of such solid supported organoiridium catalysts in dehydrogenation reactions of alkanes is provided. The catalysts can be easily recovered and recycled.

  19. Bimetallic Au-decorated Pd catalyst for the liquid phase hydrodechlorination of 2,4-dichlorophenol

    International Nuclear Information System (INIS)

    Zhou, Juan; Chen, Huan; Chen, Quanyuan; Huang, Zhaolu

    2016-01-01

    Graphical abstract: 2,4-Dichlorophenol can be converted to phenol via the catalytic HDC method over Pd-Au/CNTs and the catalytic activity first increased and then decreased with Au content. - Highlights: • Bimetallic catalysts had smaller metal particles and larger number of exposed active site than the monometallic catalysts. • The cationization of Pd particles increased with Au content in the bimetallic catalysts. • The bimetallic catalysts exhibited higher catalytic activities for HDC of 2,4-DCP than the monometallic counterparts. • The concerted pathway for HDC of 2,4-DCP was more predominant with increasing Au content in the bimetallic catalyst. - Abstract: Monometallic and bimetallic Pd-Au catalysts supported on multi-walled carbon nanotubes (CNTs) with varied Au cooperation amounts were prepared using the complexing-reduction method in the presence of tetrahydrofuran (THF). The liquid phase catalytic hydrodechlorination (HDC) of 2,4-dichlorophenol (2,4-DCP) was investigated over these bimetallic catalysts. The catalysts were characterized by N 2 adsorption-desorption isotherms, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and H 2 chemisorption. Characterization results showed that the co-reduction of Pd and Au mainly formed alloy-like structure. The bimetallic catalysts had smaller metal particles and larger numbers of exposed active site than that of monometallic catalysts. In addition, compared with Pd(1.7)/CNTs and Au(0.4)/CNTs, the binding energies of Pd 3d 5/2 shifted to higher positions while that of Au 4f 7/2 had negative shifts in the Pd-Au bimetallic catalysts, which can be ascribed to the electrons transferred from metal Pd to Au and the cationization of Pd particles was enhanced. Accordingly, the bimetallic Pd-Au particles with different Au contents in the catalysts exhibited varied synergistic effects for the catalytic HDC of 2,4-DCP, with Pd(1.8)Au(0.4)/CNTs having the highest catalytic activity

  20. ATTRITION RESISTANT IRON-BASED FISCHER-TROPSCH CATALYSTS

    Energy Technology Data Exchange (ETDEWEB)

    K. Jothimurugesan; James G. Goodwin, Jr.; Santosh K. Gangwal

    1999-10-01

    Fischer-Tropsch (FT) synthesis to convert syngas (CO + H{sub 2}) derived from natural gas or coal to liquid fuels and wax is a well-established technology. For low H{sub 2} to CO ratio syngas produced from CO{sub 2} reforming of natural gas or from gasification of coal, the use of Fe catalysts is attractive because of their high water gas shift activity in addition to their high FT activity. Fe catalysts are also attractive due to their low cost and low methane selectivity. Because of the highly exothermic nature of the FT reaction, there has been a recent move away from fixed-bed reactors toward the development of slurry bubble column reactors (SBCRs) that employ 30 to 90 {micro}m catalyst particles suspended in a waxy liquid for efficient heat removal. However, the use of FeFT catalysts in an SBCR has been problematic due to severe catalyst attrition resulting in fines that plug the filter employed to separate the catalyst from the waxy product. Fe catalysts can undergo attrition in SBCRs not only due to vigorous movement and collisions but also due to phase changes that occur during activation and reaction.

  1. Catalyst, method of making, and reactions using the catalyst

    Science.gov (United States)

    Tonkovich, Anna Lee Y [Pasco, WA; Wang, Yong [Richland, WA; Gao, Yufei [Kennewick, WA

    2002-08-27

    The present invention includes a catalyst having a layered structure with, (1) a porous support, (2) a buffer layer, (3) an interfacial layer, and optionally (4) a catalyst layer. The invention also provides a process in which a reactant is converted to a product by passing through a reaction chamber containing the catalyst.

  2. Oxide Nanocrystal Model Catalysts.

    Science.gov (United States)

    Huang, Weixin

    2016-03-15

    Model catalysts with uniform and well-defined surface structures have been extensively employed to explore structure-property relationships of powder catalysts. Traditional oxide model catalysts are based on oxide single crystals and single crystal thin films, and the surface chemistry and catalysis are studied under ultrahigh-vacuum conditions. However, the acquired fundamental understandings often suffer from the "materials gap" and "pressure gap" when they are extended to the real world of powder catalysts working at atmospheric or higher pressures. Recent advances in colloidal synthesis have realized controlled synthesis of catalytic oxide nanocrystals with uniform and well-defined morphologies. These oxide nanocrystals consist of a novel type of oxide model catalyst whose surface chemistry and catalysis can be studied under the same conditions as working oxide catalysts. In this Account, the emerging concept of oxide nanocrystal model catalysts is demonstrated using our investigations of surface chemistry and catalysis of uniform and well-defined cuprous oxide nanocrystals and ceria nanocrystals. Cu2O cubes enclosed with the {100} crystal planes, Cu2O octahedra enclosed with the {111} crystal planes, and Cu2O rhombic dodecahedra enclosed with the {110} crystal planes exhibit distinct morphology-dependent surface reactivities and catalytic properties that can be well correlated with the surface compositions and structures of exposed crystal planes. Among these types of Cu2O nanocrystals, the octahedra are most reactive and catalytically active due to the presence of coordination-unsaturated (1-fold-coordinated) Cu on the exposed {111} crystal planes. The crystal-plane-controlled surface restructuring and catalytic activity of Cu2O nanocrystals were observed in CO oxidation with excess oxygen. In the propylene oxidation reaction with O2, 1-fold-coordinated Cu on Cu2O(111), 3-fold-coordinated O on Cu2O(110), and 2-fold-coordinated O on Cu2O(100) were identified

  3. Enhanced activity of Pt/CNTs anode catalyst for direct methanol fuel cells using Ni2P as co-catalyst

    Science.gov (United States)

    Li, Xiang; Luo, Lanping; Peng, Feng; Wang, Hongjuan; Yu, Hao

    2018-03-01

    The direct methanol fuel cell is a promising energy conversion device because of the utilization of the state-of-the-art platinum (Pt) anode catalyst. In this work, novel Pt/Ni2P/CNTs catalysts were prepared by the H2 reduction method. It was found that the activity and stability of Pt for methanol oxidation reaction (MOR) could be significantly enhanced while using nickel phosphide (Ni2P) nanoparticles as co-catalyst. X-ray photoelectron spectroscopy revealed that the existence of Ni2P affected the particle size and electronic distribution of Pt obviously. Pt/CNTs catalyst, Pt/Ni2P/CNTs catalysts with different Ni2P amount were synthesized, among which Pt/6%Ni2P/CNTs catalyst exhibited the best MOR activity of 1400 mAmg-1Pt, which was almost 2.5 times of the commercial Pt/C-JM catalyst. Moreover, compared to other Pt-based catalysts, this novel Pt/Ni2P/CNTs catalyst also exhibited higher onset current density and better steady current density. The result of this work may provide positive guidance to the research on high efficiency and stability of Pt-based catalyst for direct methanol fuel cells.

  4. Fuel cell catalyst degradation

    DEFF Research Database (Denmark)

    Arenz, Matthias; Zana, Alessandro

    2016-01-01

    Fuel cells are an important piece in our quest for a sustainable energy supply. Although there are several different types of fuel cells, the by far most popular is the proton exchange membrane fuel cell (PEMFC). Among its many favorable properties are a short start up time and a high power density...... increasing focus. Activity of the catalyst is important, but stability is essential. In the presented perspective paper, we review recent efforts to investigate fuel cell catalysts ex-situ in electrochemical half-cell measurements. Due to the amount of different studies, this review has no intention to give...

  5. Olefin metathesis catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Kukes, S.G.; Banks, R.L.

    1986-05-20

    A process is described for preparing a disproportionation catalyst comprising admixing a catalytically effective amount of a calcined and activated catalyst consisting essentially of at least one metal oxide selected from molybdenum oxide and tungsten oxide and a support containing a major proportion of silica or alumina with a promoting amount of a methylating agent selected from the group consisting of dimethyl sulfate, dimethylsulfoxide, trimethyloxonium tetrafluorborate, methyl iodide, and methyl bromide, and subjecting same to inert atmospheric conditions for the methylating agent to promote the activity of the calcined molybdenum and tungsten oxides for the disproportionation of olefins.

  6. The deuterium-exchange reaction between water and hydrogen with the thin-film hydrophobic catalyst

    International Nuclear Information System (INIS)

    Yamashita, Hisao; Mizumoto, Mamoru; Matsuda, Shimpei

    1985-01-01

    The deuterium-exchange reaction between water and hydrogen with a hydrophobic catalyst was studied. The hydrophobic catalyst was composed of platinum as an active component and porous poly(tetrafluoroethylene) (PTFE) as a support. The PTFE support was in two forms, i.e., (a) a pellet and (b) a thin-film with the thickness of 50 μm. The primary purpose of the thin film hydrophobic catalyst was to reduce the platinum usage in the reactor. The activity of the catalyst was measured in a trickle bed reactor at atmospheric pressure and temperature of 20 ∼ 70 deg C. It has been found that the employment of the thin-film catalyst reduced the platinum usage to 1/5 of the reactor in the case of using a conventional catalyst. Platinum particles on the thin-film catalyst work efficiently because the reactants were easily diffused to the active sites. It has also been found that the isotopic exchange rate with the thin-film catalyst increased with the increase in the ratio of liquid/gas and increased with the rise of the reaction temperature. It was found from an endurance test that the activity of the thin-film catalyst decreased gradually due to the condensation of water vapor in the catalyst, but was regenarated by heating the catalyst to remove the condensed water. (author)

  7. Recovering platinum-group metals from auto catalysts

    International Nuclear Information System (INIS)

    Hoffmann, J.E.

    1988-01-01

    A variety of technical challenges confront the prospective processor of spent automotive catalysts, including a frequently high (1-10%) lead content; the presence of alumina in both soluble, γ, and insoluble, α, forms; the need for recovery of greater than 90% to assure an economical process; the disposition and control of process effluents, refractory residues, and lead metal salts from catalyst processing; and the highly aggressive and corrosive reagents required. Six different processes for recovery of platinum, palladium and rhodium are described and compared on the basis of their utility and how well they meet these technical challenges

  8. Deactivation-resistant catalyst for selective catalyst reduction of NOx

    DEFF Research Database (Denmark)

    2011-01-01

    The present invention relates to a catalyst for selective catalytic reduction of NOx in alkali metal containing flue gas using ammonia as reductant, the catalyst comprising a surface with catalytically active sites, wherein the surface is at least partly coated with a coating comprising at least...... one metal oxide. In another aspect the present invention relates to the use of said catalyst and to a method of producing said catalyst. In addition, the present invention relates to a method of treating an catalyst for conferring thereon an improved resistance to alkali poisoning....

  9. Effect of the dispersants on Pd species and catalytic activity of supported palladium catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Yue [Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430205 (China); Yang, Xiaojun, E-mail: 10100201@wit.edu.cn [Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430205 (China); Cao, Shuo, E-mail: cao23@email.sc.edu [North America R& D Center, Clariant BU Catalysts, Louisville, 40209, KY (United States); Zhou, Jie [Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430205 (China); Wu, Yuanxin [Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430205 (China); School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Han, Jinyu [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Yan, Zhiguo [Key Laboratory for Green Chemical Process of Ministry of Education, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430205 (China); Zheng, Mingming [Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Hubei Key Laboratory of Oilcrops Lipid Chemistry and Nutrition, Wuhan 430062 (China)

    2017-04-01

    Highlights: • Polyvinyl alcohol (PVA) inhibited the sintering and reduction of Pd nanoparticles. • Activity was improved for supported Pd catalysts with PVA modified method. • PVA modified method minimized the catalyst deactivation. • This work provides an insight of the regeneration strategies for Pd catalysts. - Abstract: A series of supported palladium catalysts has been prepared through the precipitation method and the reduction method, using polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP) as dispersants. The effects of the dispersants on the properties of catalysts were evaluated and the catalytic performance of the new materials was investigated for the oxidative carbonylation of phenol to diphenyl carbonate (DPC). The catalysts as prepared were also characterized by the X-ray diffraction (XRD), transmission electron microscope (TEM), Brunner-Emmet-Teller (BET) measurements and X-ray photoelectron spectroscopy (XPS) techniques. The results show that the addition of the dispersants had no effect on the crystal phase of the catalysts. However, the dispersion of Pd particles was improved when the dispersants were used. Moreover, the particle sizes of Pd nanoparticles modified by PVA were smaller than those modified by PVP. The catalysts prepared using the dispersants gave better yields of DPC than the catalysts prepared without the dispersants. The highest yield of DPC was 17.9% with the PVA-Red catalyst. The characterization results for the used catalysts showed that the Pd species in the PVA-Red catalyst remained mostly divalent and the lattice oxygen species were consumed during the reaction, which could lead to the higher catalytic activity of the PVA-Red catalyst. The experimental results confirm that PVA effectively inhibited the sintering and reduction of active Pd species in the oxidative carbonylation of phenol.

  10. Constrained Geometry Organotitanium Catalysts Supported on Nanosized Silica for Ethylene (co)Polymerization.

    Science.gov (United States)

    Li, Kuo-Tseng; Wu, Ling-Huey

    2017-05-05

    Supported olefin polymerization catalysts can prevent reactor-fouling problems and produce uniform polymer particles. Constrained geometry complexes (CGCs) have less sterically hindered active sites than bis-cyclopentadienyl metallocene catalysts. In the literature, micrometer-sized silica particles were used for supporting CGC catalysts, which might have strong mass transfer limitations. This study aims to improve the activity of supported CGC catalysts by using nanometer-sized silica. Ti[(C₅Me₄)SiMe₂(N t Bu)]Cl₂, a "constrained-geometry" titanium catalyst, was supported on MAO-treated silicas (nano-sized and micro-sized) by an impregnation method. Ethylene homo-polymerization and co-polymerization with 1-octene were carried out in a temperature range of 80-120 °C using toluene as the solvent. Catalysts prepared and polymers produced were characterized. For both catalysts and for both reactions, the maximum activities occurred at 100 °C, which is significantly higher than that (60 °C) reported before for supported bis-cyclopentadienyl metallocene catalysts containing zirconium, and is lower than that (≥140 °C) used for unsupported Ti[(C₅Me₄)SiMe₂(N t Bu)]Me₂ catalyst. Activities of nano-sized catalyst were 2.6 and 1.6 times those of micro-sized catalyst for homopolymerization and copolymerization, respectively. The former produced polymers with higher crystallinity and melting point than the latter. In addition, copolymer produced with nanosized catalyst contained more 1-octene than that produced with microsized catalyst.

  11. Discerning the Location and Nature of Coke Deposition from Surface to Bulk of Spent Zeolite Catalysts

    OpenAIRE

    Devaraj, Arun; Vijayakumar, Murugesan; Bao, Jie; Guo, Mond F.; Derewinski, Miroslaw A.; Xu, Zhijie; Gray, Michel J.; Prodinger, Sebastian; Ramasamy, Karthikeyan K.

    2016-01-01

    The formation of carbonaceous deposits (coke) in zeolite pores during catalysis leads to temporary deactivation of catalyst, necessitating regeneration steps, affecting throughput, and resulting in partial permanent loss of catalytic efficiency. Yet, even to date, the coke molecule distribution is quite challenging to study with high spatial resolution from surface to bulk of the catalyst particles at a single particle level. To address this challenge we investigated the coke molecules in HZS...

  12. Olefin metathesis and catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Kukes, S. G.; Banks, R. L.

    1985-05-14

    Olefins are converted into other olefins having different numbers of carbon atoms by contact with a catalyst comprising an inorganic refractory oxide support containing at least one of tungsten oxide and molybdenum oxide and a promoting amount of at least one methylating agent under conditions suitable for the methylating agent compounds to promote the activity of tungsten and molybdenum oxides for the disproportionation reaction.

  13. 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.

  14. Sabatier Catalyst Poisoning Investigation

    Science.gov (United States)

    Nallette, Tim; Perry, Jay; Abney, Morgan; Knox, Jim; Goldblatt, Loel

    2013-01-01

    The Carbon Dioxide Reduction Assembly (CRA) on the International Space Station (ISS) has been operational since 2010. The CRA uses a Sabatier reactor to produce water and methane by reaction of the metabolic CO2 scrubbed from the cabin air and the hydrogen byproduct from the water electrolysis system used for metabolic oxygen generation. Incorporating the CRA into the overall air revitalization system has facilitated life support system loop closure on the ISS reducing resupply logistics and thereby enhancing longer term missions. The CRA utilizes CO2 which has been adsorbed in a 5A molecular sieve within the Carbon Dioxide Removal Assembly, CDRA. There is a potential of compounds with molecular dimensions similar to, or less than CO2 to also be adsorbed. In this fashion trace contaminants may be concentrated within the CDRA and subsequently desorbed with the CO2 to the CRA. Currently, there is no provision to remove contaminants prior to entering the Sabatier catalyst bed. The risk associated with this is potential catalyst degradation due to trace organic contaminants in the CRA carbon dioxide feed acting as catalyst poisons. To better understand this risk, United Technologies Aerospace System (UTAS) has teamed with MSFC to investigate the impact of various trace contaminants on the CRA catalyst performance at relative ISS cabin air concentrations and at about 200/400 times of ISS concentrations, representative of the potential concentrating effect of the CDRA molecular sieve. This paper summarizes our initial assessment results.

  15. ALKALI RESISTANT CATALYST

    DEFF Research Database (Denmark)

    2008-01-01

    of alkali metal and/or alkali-earth compounds which process comprises using a catalyst combined of (i) a formed porous superacidic support, said superacidic support having an Hammett acidity stronger than Ho=-12, and (ii) a metal oxide catalytic component deposited on said superacidic support selected from...

  16. Catalytic hydrothermal liquefaction (HTL of biomass for bio-crude production using Ni/HZSM-5 catalysts

    Directory of Open Access Journals (Sweden)

    Shouyun Cheng

    2017-04-01

    Full Text Available Hydrothermal liquefaction (HTL is an effective method that can convert biomass into bio-crude, but direct use of bio-crude derived from biomass HTL remains a challenge due to the lower quality. In this study, bifunctional Ni/HZSM-5 catalysts and zinc hydrolysis were combined to produce upgraded bio-crude in an in-situ HTL process. The K2CO3 and HZSM-5 catalysts with different Ni loading ratios were tested. The effects of different catalysts on the yield and quality of bio-crude and gas were investigated. The results indicated that the catalysts improved bio-crude and gas yields, compared to pine sawdust liquefaction without catalyst. The catalysts reduced the contents of undesirable oxygenated compounds such as acids, ketones, phenols, alcohols and esters in bio-crude products while increased desirable hydrocarbons content. K2CO3 produced highest bio-crude yield and lowest solid residue yield among all catalysts. Compared to parent HZSM-5 catalyst, bifunctional Ni/HZSM-5 catalysts exhibited higher catalyst activity to improve quality of upgraded bio-crude due to its integration of cracking and hydrodeoxygenation reactions. 6%Ni/HZSM-5 catalyst produced the bio-crude with the highest hydrocarbons content at 11.02%. This catalyst can be a candidate for bio-crude production from biomass HTL.

  17. Electron microscopic studies of natural gas oxidation catalyst – Effects of thermally accelerated aging on catalyst microstructure

    DEFF Research Database (Denmark)

    Honkanen, Mari; Hansen, Thomas Willum; Jiang, Hua

    2017-01-01

    Structural changes of PtPd nanoparticles in a natural gas oxidation catalyst were studied at elevated temperatures in air and low-oxygen conditions and in situ using environmental transmission electron microscopy (ETEM). The fresh catalyst shows particles on the c-Al2O3 support....... At 700 °C, the noble metal oxide decomposes and Pt gets trapped by PdO particles followed by formation of metallic Pd and Pt containing particles. At 1000 ºC, the particles had a metallic Pd and Pt containing core surrounded by PdO particles. In addition, the presence of particles was always...... observed. The activity measurements indicate the decrease in activity at the elevated temperatures. ETEM studies showed significant mobility of the noble metal particles above 850 C. Above 1100 °C, PtPd particles were mobile and smaller particles were trapped by larger ones by a particle coalescence...

  18. Catalyst support structure, catalyst including the structure, reactor including a catalyst, and methods of forming same

    Science.gov (United States)

    Van Norman, Staci A.; Aston, Victoria J.; Weimer, Alan W.

    2017-05-09

    Structures, catalysts, and reactors suitable for use for a variety of applications, including gas-to-liquid and coal-to-liquid processes and methods of forming the structures, catalysts, and reactors are disclosed. The catalyst material can be deposited onto an inner wall of a microtubular reactor and/or onto porous tungsten support structures using atomic layer deposition techniques.

  19. Feasibility evaluation of using spent FCC catalyst for metals treatment from industrial waste; Avaliacao do potencial de recuperacao de niquel de catalisadores equilibrados (E-CAT) atraves da tecnica de remediacao eletrocinetica

    Energy Technology Data Exchange (ETDEWEB)

    Baptista, Adalberto; Ponte, Haroldo de Araujo [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil)

    2004-07-01

    The purpose of this work is to describe the feasibility evaluation using FCC catalyst for treatment from industrial wastes increasing the life time of the spent catalysts and reducing the environmental impact. Evaluated the reutilization of catalyst in process recovery of nickel adsorbed. The technique used was the Electrokinetic Remediation. This technique is based in application of a direct current of low intensity or low potential between the electrodes located in soil. The pollutants are mobilized how loaded species or particles. It used a electrokinetic reactor with approximated volume of 1200 cm{sup 3}, where the residue is placed. In your extremity are adapted two cameras of acrylic, being one anodic, with steel inox 304 electrode, and other cathodic, with lead electrode. In anodic camera, it was injected, with aid a bomb, a solution of sulfuric acid, which work as electrolyte, to a flow rate of 20 ml/h. Was evaluated the desorption of Nickel in the equilibrium catalyst submitting a variation of the conditions of the concentration and potential. (author)

  20. Ordered mesoporous materials as model supports to study catalyst preparation

    NARCIS (Netherlands)

    Sietsma, J.R.A.

    2007-01-01

    Catalysts are indispensable to modern-day society because of their prominent role in petroleum refining, chemical processing, and the reduction of environmental pollution. The catalytically active component often consists of small metal (oxide) particles that are supported on a carrier such as

  1. Preparation of Pt–Ru bimetallic catalyst supported on carbon ...

    Indian Academy of Sciences (India)

    Unknown

    ssion electron microscopic investigation reveals that Pt–Ru nanoparticles are highly dispersed inside the tube with an average particle size of 1⋅7 nm. Keywords. Carbon nanotubes; template synthesis; fuel cell catalyst; nanoparticles. 1. Introduction. There is a considerable interest currently in developing nanostructured ...

  2. Direct evidence of atomic-scale structural fluctuations in catalyst nanoparticles.

    Science.gov (United States)

    Lin, Pin Ann; Gomez-Ballesteros, Jose L; Burgos, Juan C; Balbuena, Perla B; Natarajan, Bharath; Sharma, Renu

    2017-05-01

    Rational catalyst design requires an atomic scale mechanistic understanding of the chemical pathways involved in the catalytic process. A heterogeneous catalyst typically works by adsorbing reactants onto its surface, where the energies for specific bonds to dissociate and/or combine with other species (to form desired intermediate or final products) are lower. Here, using the catalytic growth of single-walled carbon nanotubes (SWCNTs) as a prototype reaction, we show that the chemical pathway may in-fact involve the entire catalyst particle, and can proceed via the fluctuations in the formation and decomposition of metastable phases in the particle interior. We record in situ and at atomic resolution, the dynamic phase transformations occurring in a Cobalt catalyst nanoparticle during SWCNT growth, using a state-of-the-art environmental transmission electron microscope (ETEM). The fluctuations in catalyst carbon content are quantified by the automated, atomic-scale structural analysis of the time-resolved ETEM images and correlated with the SWCNT growth rate. We find the fluctuations in the carbon concentration in the catalyst nanoparticle and the fluctuations in nanotube growth rates to be of complementary character. These findings are successfully explained by reactive molecular dynamics (RMD) simulations that track the spatial and temporal evolution of the distribution of carbon atoms within and on the surface of the catalyst particle. We anticipate that our approach combining real-time, atomic-resolution image analysis and molecular dynamics simulations will facilitate catalyst design, improving reaction efficiencies and selectivity towards the growth of desired structure.

  3. Particle Pollution

    Science.gov (United States)

    ... Your Health Particle Pollution Public Health Issues Particle Pollution Recommend on Facebook Tweet Share Compartir Particle pollution — ... see them in the air. Where does particle pollution come from? Particle pollution can come from two ...

  4. Production of perovskite catalysts on ceramic monoliths with nanoparticles for dual fuel system automobiles

    International Nuclear Information System (INIS)

    Khanfekr, A.; Arzani, K.; Nemati, A.; Hosseini, M.

    2009-01-01

    (Lanthanum, Cerium)(Iron, Manganese, Cobalt, Palladium)(Oxygen) 3 ,-Perovskite catalyst was prepared by the citrate route and deposited on ceramic monoliths via dip coating procedure. The catalyst was applied on a car with X U 7 motors and the amount of emission was monitored with vehicle emission test systems in Sapco company. The results were compared with the imported catalyst with noble metals such as Palladium, Platinum and Rhodium by Iran Khodro company based on the Euro III standards. The catalysts were characterized by specific surface area measurements, scanning electron microscopy, X-ray diffraction, line scan and map. In the results, obtained in the home made sample, the amount of carbon monoxide, nitrogen oxides and hydrocarbons were lower than imported catalyst with Iran Khodro company with nobel metals. The illustration shows nano particles size on coat. The microstructure evaluation showed that the improved properties can be related to the existence of nano particles on coating

  5. Deuterium isotopic exchange reaction on the surface of promoted nickel catalysts+

    International Nuclear Information System (INIS)

    Abou EL-Nour, F.; Abdel-Badei, M.M.; Belacy, N.

    1987-01-01

    Nickel catalysts promoted with different metal oxides proved to be efficient for the isotopic exchange of deuterium between hydrogen and water in the vapour phase. Estimation of the surface properties of this type of catalysts led to the correlation of the specific catalytic activity with their surface characteristics. The particle size of nickel content of the catalysts under investigation was determined from the surface area measurements. The equation used for particle size determination is a corrected one. The correction is based on the probability of sharing the 6-faces of cubic nickel crystals, present in the promoted catalyst, in the isotopic exchange process. It may be also due to the increased porosity of the components of the catalyst mixture. The results demonstrate the probability of migration of nickel crystals during the isotopic exchange reaction of deuterium between hydrogen and water in the vapour state on the surface of nickel catalysis promoted with different metal oxides

  6. Gaseous exchange reaction of deuterium between hydrogen and water on hydrophobic catalyst supporting platinum

    International Nuclear Information System (INIS)

    Izawa, Hirozumi; Isomura, Shohei; Nakane, Ryohei.

    1979-01-01

    The deuterium exchange reaction between hydrogen and water in the gas phase where the fed hydrogen gas is saturated with water vapor is studied experimentally by use of the proper hydrophobic catalysts supporting platinum. It is found that the activities of those catalysts for this reaction system are very high compared with the other known ones for the systems in which gas and liquid should coexist on catalyst surfaces, and that the apparent catalytic activity becomes larger as the amount of platinum supported on a catalyst particle increases. By analyses of the data the following informations are obtained. The exchange reaction can be expressed by a first order reversible reaction kinetics. The pore diffusion in the catalyst particles has significant effect on the overall reaction mechanisms. (author)

  7. Mitigation of hydrogen by oxidation using nitrous oxide and noble metal catalysts

    International Nuclear Information System (INIS)

    Britton, M.D.

    1995-01-01

    This test studied the ability of a blend of nuclear-grade, noble-metal catalysts to catalyze a hydrogen/nitrous oxide reaction in an effort to mitigate a potential hydrogen (H 2 ) gas buildup in the Hanford Site Grout Disposal Facility. For gases having H 2 and a stoichiometric excess of either nitrous oxide or oxygen, the catalyst blend can effectively catalyze the H 2 oxidation reaction at a rate exceeding 380 μmoles of H 2 per hour per gram of catalyst (μmol/h/g) and leave the gas with less than a 0.15 residual H 2 Concentration. This holds true in gases with up to 2.25% water vapor and 0.1% methane. This should also hold true for gases with up to 0.1% carbon monoxide (CO) but only until the catalyst is exposed to enough CO to block the catalytic sites and stop the reaction. Gases with ammonia up to 1% may be slightly inhibited but can have reaction rates greater than 250 μmol/h/g with less than a 0.20% residual H 2 concentration. The mechanism for CO poisoning of the catalyst is the chemisorption of CO to the active catalyst sites. The CO sorption capacity (SC) of the catalyst is the total amount of CO that the catalyst will chemisorb. The average SC for virgin catalyst was determined to be 19.3 ± 2.0 μmoles of CO chemisorbed to each gram of catalyst (μmol/g). The average SC for catalyst regenerated with air was 17.3 ± 1.9 μmol/g

  8. A review of heat-treatment effects on activity and stability of PEM fuel cell catalysts for oxygen reduction reaction

    Energy Technology Data Exchange (ETDEWEB)

    Bezerra, Cicero W.B. [Institute for Fuel Cell Innovation, National Research Council of Canada, Vancouver, BC V6T 1W5 (Canada); Department of Chemistry, Universidade Federal do Maranhao, Av. dos Portugueses, S/N 65.080-040 Sao Luis, MA (Brazil); Zhang, Lei; Liu, Hansan; Lee, Kunchan; Wang, Haijiang; Zhang, Jiujun [Institute for Fuel Cell Innovation, National Research Council of Canada, Vancouver, BC V6T 1W5 (Canada); Marques, Aldalea L.B. [Department of Technology Chemistry, Universidade Federal do Maranhao, Sao Luis, MA (Brazil); Marques, Edmar P. [Department of Chemistry, Universidade Federal do Maranhao, Av. dos Portugueses, S/N 65.080-040 Sao Luis, MA (Brazil)

    2007-11-15

    This paper reviews over 120 papers regarding the effect of heat treatment on the catalytic activity and stability of proton exchange membrane (PEM) fuel cell catalysts. These catalysts include primarily unsupported and carbon-supported platinum (Pt), Pt alloys, non-Pt alloys, and transition metal macrocycles. The heat treatment can induce changes in catalyst properties such as particle size, morphology, dispersion of the metal on the support, alloying degree, active site formation, catalytic activity, and catalytic stability. The optimum heat-treatment temperature and time period are strongly dependent on the individual catalyst. With respect to Pt-based catalysts, heat treatment can induce particle-size growth, better alloying degree, and changes in the catalyst surface morphology from amorphous to more ordered states, all of which have a remarkable effect on oxygen reduction reaction (ORR) activity and stability. However, heat treatment of the catalyst carbon supports can also significantly affect the ORR catalytic activity of the supported catalyst. Regarding non-noble catalysts, in particular transition metal macrocycles, heat treatment is also important in ORR activity and stability improvement. In fact, heat treatment is a necessary step for introducing more active catalytic sites. For metal chalcogenide catalysts, it seems that heat treatment may not be necessary for catalytic activity and stability improvement. More research is necessary to improve our fundamental understanding and to develop a new strategy that includes innovative heat-treatment processes for enhancing fuel cell catalyst activity and stability. (author)

  9. A review of heat-treatment effects on activity and stability of PEM fuel cell catalysts for oxygen reduction reaction

    Science.gov (United States)

    Bezerra, Cicero W. B.; Zhang, Lei; Liu, Hansan; Lee, Kunchan; Marques, Aldaléa L. B.; Marques, Edmar P.; Wang, Haijiang; Zhang, Jiujun

    This paper reviews over 120 papers regarding the effect of heat treatment on the catalytic activity and stability of proton exchange membrane (PEM) fuel cell catalysts. These catalysts include primarily unsupported and carbon-supported platinum (Pt), Pt alloys, non-Pt alloys, and transition metal macrocycles. The heat treatment can induce changes in catalyst properties such as particle size, morphology, dispersion of the metal on the support, alloying degree, active site formation, catalytic activity, and catalytic stability. The optimum heat-treatment temperature and time period are strongly dependent on the individual catalyst. With respect to Pt-based catalysts, heat treatment can induce particle-size growth, better alloying degree, and changes in the catalyst surface morphology from amorphous to more ordered states, all of which have a remarkable effect on oxygen reduction reaction (ORR) activity and stability. However, heat treatment of the catalyst carbon supports can also significantly affect the ORR catalytic activity of the supported catalyst. Regarding non-noble catalysts, in particular transition metal macrocycles, heat treatment is also important in ORR activity and stability improvement. In fact, heat treatment is a necessary step for introducing more active catalytic sites. For metal chalcogenide catalysts, it seems that heat treatment may not be necessary for catalytic activity and stability improvement. More research is necessary to improve our fundamental understanding and to develop a new strategy that includes innovative heat-treatment processes for enhancing fuel cell catalyst activity and stability.

  10. Synthesis and characterization of metal oxide promoted alumina catalyst for biofuel production

    Science.gov (United States)

    Anisuzzaman, S. M.; Krishnaiah, D.; Bono, A.; Abang, S.; Sundang, M.; Suali, E.; Lahin, F. A.; Shaik Alawodeen, A.

    2016-06-01

    Alumina has been widely used as a support in catalysis process which owing to its extremely thermal and mechanical stability, high surface area, large pore size and pore volume. The aim of this study was to synthesize calcium oxide-supported basic alumina catalysts (CaO/Al2O3) by impregnation method and to characterize the properties of the catalyst based on its surface area and porosity, functional group, surface morphology and particle size. Impregnation method was chosen for the synthesization of catalyst which involved contacting the support with the impregnating solution for a particular period of time, drying the support to remove the imbibed liquid and calcination process. In the preparation of catalyst, catalytic performance of CaO/Al2O3 catalyst was measured at different calcined temperatures (650°C, 750°C and 800°C). Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Mercury intrusion porosimetry (MIP), and particle size analyzer (Zetasizer) was used to characterize the catalyst. The highest total specific area and the total porosity of the catalyst was obtained at 750oC. FTIR analysis basically studied on the functional groups present in each catalyst synthesized, while SEM analysis was observed to have pores on its surface. Moreover, CaO/Al2O3 catalysts at 650°C produced the smallest particle size (396.1 mn), while at 750°C produced the largest particle size (712.4 mn). Thus it can be concluded that CaO/Al2O3 catalysts has great potential coimnercialization since CaO has attracted many attentions compared to other alkali earth metal oxides especially on the transesterification reaction.

  11. Dynamic Hydrogen Production from Methanol/Water Photo-Splitting Using Core@Shell-Structured CuS@TiO2 Catalyst Wrapped by High Concentrated TiO2 Particles

    Directory of Open Access Journals (Sweden)

    Younghwan Im

    2013-01-01

    Full Text Available This study focused on the dynamic hydrogen production ability of a core@shell-structured CuS@TiO2 photocatalyst coated with a high concentration of TiO2 particles. The rectangular-shaped CuS particles, 100 nm in length and 60 nm in width, were surrounded by a high concentration of anatase TiO2 particles (>4~5 mol. The synthesized core@shell-structured CuS@TiO2 particles absorbed a long wavelength (a short band gap above 700 nm compared to that pure TiO2, which at approximately 300 nm, leading to easier electronic transitions, even at low energy. Hydrogen evolution from methanol/water photo-splitting over the core@shell-structured CuS@TiO2 photocatalyst increased approximately 10-fold compared to that over pure CuS. In particular, 1.9 mmol of hydrogen gas was produced after 10 hours when 0.5 g of 1CuS@4TiO2 was used at pH = 7. This level of production was increased to more than 4-fold at higher pH. Cyclic voltammetry and UV-visible absorption spectroscopy confirmed that the CuS in CuS@TiO2 strongly withdraws the excited electrons from the valence band in TiO2 because of the higher reduction potential than TiO2, resulting in a slower recombination rate between the electrons and holes and higher photoactivity.

  12. Hydroformylation of 1-Hexene over Rh/Nano-Oxide Catalysts

    Directory of Open Access Journals (Sweden)

    Sari Suvanto

    2013-03-01

    Full Text Available The effect of nanostructured supports on the activity of Rh catalysts was studied by comparing the catalytic performance of nano- and bulk-oxide supported Rh/ZnO, Rh/SiO2 and Rh/TiO2 systems in 1-hexene hydroformylation. The highest activity with 100% total conversion and 96% yield of aldehydes was obtained with the Rh/nano-ZnO catalyst. The Rh/nano-ZnO catalyst was found to be more stable and active than the corresponding rhodium catalyst supported on bulk ZnO. The favorable morphology of Rh/nano-ZnO particles led to an increased metal content and an increased number of weak acid sites compared to the bulk ZnO supported catalysts. Both these factors favored the improved catalytic performance. Improvements of catalytic properties were obtained also with the nano-SiO2 and nano-TiO2 supports in comparison with the bulk supports. All of the catalysts were characterized by scanning electron microscope (SEM, inductively coupled plasma mass spectrometry (ICP-MS, BET, powder X-ray diffraction (PXRD and NH3- temperature-programmed desorption (TPD.

  13. Dynamics of Catalyst Nanoparticles

    DEFF Research Database (Denmark)

    Hansen, Thomas Willum; Cavalca, Filippo; Wagner, Jakob Birkedal

    Transmission electron microscopy (TEM) is extensively used in catalysis research. Recent developments in aberration correction allows imaging surface structures with unprecedented resolution. Using these correctors in conjunction with environmental TEM (ETEM), where imaging of materials can be done...... under gas exposure, dynamic phenomena such as sintering and growth can be observed with sub-Ångstrøm resolution. Metal nanoparticles contain the active sites in heterogeneous catalysts, which are important for many industrial applications including the production of clean fuels, chemicals...... and pharmaceuticals, and the cleanup of exhaust from automobiles and stationary power plants. Sintering, or thermal deactivation, is an important mechanism for the loss of catalyst activity. In order to initiate a systematic study of the dynamics and sintering of nanoparticles, various catalytic systems have been...

  14. Mesoporous molecular sieve catalysts

    DEFF Research Database (Denmark)

    Højholt, Karen Thrane

    This thesis deals with a very specific class of molecular sieves known as zeolites. Zeolites are a class of crystalline aluminosilicates characterised by pores or cavities of molecular dimensions as part of their crystal structure. In this work zeolites were modified for the use and understanding...... of different catalytic applications. Primarily the zeolites were modified regarding the porosity and the introduction of metals to the framework. The obtained materials were used as solid acid catalysts, as an inert matrix for stabilising metal nanoparticles and as an anchoring material for molecular metal....... Furthermore, preliminary work was done using mesoporous ZSM-5 zeolites as support material for anchoring molecular CoMo6 species for the application as potential bi-functional catalyst in simultaneous hydrodesulfurisation (HDS) and hydrocracking. HDS activity tests revealed that the anchoring improved...

  15. Photo catalyst; Ko shokubai

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-07-01

    While titanium oxide is excited by the light, electrons of titanium oxide are taken away by the light energy to form positive holes. Water will be decomposed into hydrogen ion and hydroxy radical (OH) by these positive holes. This hydroxy radical is a strong reactive substance called active oxygen, it decomposes organisms. Besides this photo- catalyst function, the titanium oxide can also make surface of a substance superhydrophilic. The super hydrophilicity results in not forming water drops on the glass surface but spreading all over the surface to prevent a covering of fog on the glass surface. The published patents concerning the photo catalysts were 593 from Jan. 1998 to Jan. 1999. The applicant order is the first TOTO 143, the second Daikin Industry 19, the third Toshiba Raitech, Nitto Denko, Hitachi 17 respectively. (NEDO)

  16. High-Activity Dealloyed Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Kongkanand, Anusorn [General Motors LLC, Pontiac, MI (United States)

    2014-09-30

    Reduction of costly Pt usage in proton exchange membrane fuel cell electrodes is one of the major challenges towards development and commercialization of fuel cell vehicles. Although few have met the initial-kinetic activity requirements in a realistic fuel cell device, no catalyst material has ever met the demanding fuel cell durability targets set by DOE. In this project, a team of 4 universities and 2 companies came together to investigate a concept that appeared promising in preliminary non-fuel cell tests then to further develop the catalyst to a mature level ready for vehicle implementation. The team consists of academia with technical leadership in their respective areas, a catalyst supplier, and a fuel cell system integrator.The tightly collaborative project enabled development of a highly active and durable catalyst with performance that significantly exceeds that of previous catalysts and meets the DOE targets for the first time (Figure 1A). The catalyst was then further evaluated in full-active-area stack in a realistic vehicle operating condition (Figure 1B). This is the first public demonstration that one can realize the performance benefit and Pt cost reduction over a conventional pure Pt catalyst in a long-term realistic PEMFC system. Furthermore, systematic analyses of a range of catalysts with different performance after fuel cell testing allowed for correlation between catalyst microstructure and its electrocatalytic activity and durability. This will in turn aid future catalyst development.

  17. Deactivation of Oxidation Catalysts

    Science.gov (United States)

    1991-05-01

    been observed to decrease CO oxidation even at 500TC ( Farrauto and Wedding, 1973, p. 254) by a sulfate formation mechanism, it is likely that the...sulfated CoO, in the study of Farrauto and Wedding (1973) and that no deactivation was observed in the previously discussed study by Pope et al...This is attributed to the adsorption of HO on the catalyst surface which competes with the adsorption of ethanol. Farrauto and Wedding (1973) studied

  18. Olefin metathesis and catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Kukes, S. G.; Banks, R. L.

    1985-03-12

    Olefins are converted into other olefins having different numbers of carbon atoms by contact with a catalyst comprising an inorganic refractory material containing at least one of tungsten oxide and molybdenum oxide and a promoting amount of at least one treating agent selected from chlorinated silicon compounds, thionyl chloride, and sulfuryl chloride under conditions suitable for the treating agent to promote the activity of tungsten and molybdenum oxides for the disporoportionation reaction.

  19. Catalyst in Basic Oleochemicals

    OpenAIRE

    Eva Suyenty; Herlina Sentosa; Mariani Agustine; Sandy Anwar; Abun Lie; Erwin Sutanto

    2007-01-01

    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 oleochemic...

  20. Dynamical properties of nano-structured catalysts for methane conversion: an in situ scattering study

    DEFF Research Database (Denmark)

    Kehres, Jan

    The reactivity of catalyst particles can be radically enhanced by decreasing their size down to the nanometer range. The nanostructure of a catalyst can have an enormous and positive influence on the reaction rate, for example strong structure sensitivity was observed for methane reforming...... and ammonia synthesis, and it is therefore crucial that catalysts preserve their nanostructures under operational conditions. Fundamental understanding of the relation between the catalytic activity and the morphology of the nanoparticle, their crystallinity and crystallite size, is required to improve....../NiO particles in a fresh catalyst sample showed a Ni/NiO core shell structure. The Ni lattice parameter decreased during the reduction due to the release of stress between the Ni core and the NiO shell. Ni particles sintered during heating in hydrogen after the reduction of the NiO shell. Dry reforming...

  1. Catalyst component interactions in nickel/alumina catalyst

    OpenAIRE

    Kiš Erne E.; Lazić Matilda M.; Bošković Goran C.

    2007-01-01

    The influence of nickel loading (5; 10; 20 wt% Ni), temperature of heat treatment (400; 700; 1100°C) and way of catalyst preparation on the catalyst component interactions (CCI) in the impregnated, mechanical powder mixed and co-precipitated catalyst was investigated. For sample characterization, low temperature nitrogen adsorption (LTNA) and X-ray diffraction (XRD) were applied. Significant differences were revealed, concerning CCI in dependence of nickel loading, temperature of heat treatme...

  2. Structure–activity relationships of Pt/Al2O3 catalysts for CO and NO oxidation at diesel exhaust conditions

    DEFF Research Database (Denmark)

    Boubnov, Alexey; Dahl, Søren; Johnson, Erik

    2012-01-01

    Structure–performance relationships for Pt/Al2O3 catalysts with mean Pt particle sizes of 1, 2, 3, 5 and 10nm are investigated for the catalytic oxidation of CO and NO under lean-burning diesel exhaust conditions. The most active catalysts for CO oxidation exhibit Pt particles of 2–3nm, having a ...

  3. Novel Attrition-Resistant Fischer Tropsch Catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Weast, Logan, E.; Staats, William, R.

    2009-05-01

    There is a strong national interest in the Fischer-Tropsch synthesis process because it offers the possibility of making liquid hydrocarbon fuels from reformed natural gas or coal and biomass gasification products. This project explored a new approach that had been developed to produce active, attrition-resistant Fischer-Tropsch catalysts that are based on glass-ceramic materials and technology. This novel approach represented a promising solution to the problem of reducing or eliminating catalyst attrition and maximizing catalytic activity, thus reducing costs. The technical objective of the Phase I work was to demonstrate that glass-ceramic based catalytic materials for Fischer-Tropsch synthesis have resistance to catalytic deactivation and reduction of particle size superior to traditional supported Fischer-Tropsch catalyst materials. Additionally, these novel glass-ceramic-based materials were expected to exhibit catalytic activity similar to the traditional materials. If successfully developed, the attrition-resistant Fischer-Tropsch catalyst materials would be expected to result in significant technical, economic, and social benefits for both producers and public consumers of Fischer-Tropsch products such as liquid fuels from coal or biomass gasification. This program demonstrated the anticipated high attrition resistance of the glass-ceramic materials. However, the observed catalytic activity of the materials was not sufficient to justify further development at this time. Additional testing documented that a lack of pore volume in the glass-ceramic materials limited the amount of surface area available for catalysis and consequently limited catalytic activity. However, previous work on glass-ceramic catalysts to promote other reactions demonstrated that commercial levels of activity can be achieved, at least for those reactions. Therefore, we recommend that glass-ceramic materials be considered again as potential Fischer-Tropsch catalysts if it can be

  4. Dispersion enhanced metal/zeolite catalysts

    Science.gov (United States)

    Sachtler, Wolfgang M. H.; Tzou, Ming-Shin; Jiang, Hui-Jong

    1987-01-01

    Dispersion stabilized zeolite supported metal catalysts are provided as bimetallic catalyst combinations. The catalyst metal is in a reduced zero valent form while the dispersion stabilizer metal is in an unreduced ionic form. Representative catalysts are prepared from platinum or nickel as the catalyst metal and iron or chromium dispersion stabilizer.

  5. Monodisperse Platinum and Rhodium Nanoparticles as Model Heterogeneous Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Grass, Michael Edward [Univ. of California, Berkeley, CA (United States)

    2008-09-01

    Model heterogeneous catalysts have been synthesized and studied to better understand how the surface structure of noble metal nanoparticles affects catalytic performance. In this project, monodisperse rhodium and platinum nanoparticles of controlled size and shape have been synthesized by solution phase polyol reduction, stabilized by polyvinylpyrrolidone (PVP). Model catalysts have been developed using these nanoparticles by two methods: synthesis of mesoporous silica (SBA-15) in the presence of nanoparticles (nanoparticle encapsulation, NE) to form a composite of metal nanoparticles supported on SBA-15 and by deposition of the particles onto a silicon wafer using Langmuir-Blodgett (LB) monolayer deposition. The particle shapes were analyzed by transmission electron microscopy (TEM) and high resolution TEM (HRTEM) and the sizes were determined by TEM, X-ray diffraction (XRD), and in the case of NE samples, room temperature H2 and CO adsorption isotherms. Catalytic studies were carried out in homebuilt gas-phase reactors. For the nanoparticles supported on SBA-15, the catalysts are in powder form and were studied using the homebuilt systems as plug-flow reactors. In the case of nanoparticles deposited on silicon wafers, the same systems were operated as batch reactors. This dissertation has focused on the synthesis, characterization, and reaction studies of model noble metal heterogeneous catalysts. Careful control of particle size and shape has been accomplished though solution phase synthesis of Pt and Rh nanoparticles in order to elucidate further structure-reactivity relationships in noble metal catalysis.

  6. Catalytic hydrodechlorination of trichloroethylene in a novel NaOH/2-propanol/methanol/water system on ceria-supported Pd and Rh catalysts.

    Science.gov (United States)

    Cobo, Martha; Becerra, Jorge; Castelblanco, Miguel; Cifuentes, Bernay; Conesa, Juan A

    2015-08-01

    The catalytic hydrodechlorination (HDC) of high concentrations of trichloroethylene (TCE) (4.9 mol%, 11.6 vol%) was studied over 1%Pd, 1%Rh and 0.5%Pd-0.5%Rh catalysts supported on CeO2 under conditions of room temperature and pressure. For this, a one-phase system of NaOH/2-propanol/methanol/water was designed with molar percentages of 13.2/17.5/36.9/27.6, respectively. In this system, the alcohols delivered the hydrogen required for the reaction through in-situ dehydrogenation reactions. PdRh/CeO2 was the most active catalyst for the degradation of TCE among the evaluated materials, degrading 85% of the trichloroethylene, with alcohol dehydrogenation rates of 89% for 2-propanol and 83% for methanol after 1 h of reaction. Fresh and used catalysts were characterized by Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), and Thermogravimetric analysis (TGA). These results showed important differences of the active phase in each catalyst sample. Rh/CeO2 had particle sizes smaller than 1 nm and the active metal was partially oxidized (Rh(0)/Rh(+δ) ratio of 0.43). This configuration showed to be suitable for alcohols dehydrogenation. On the contrary, Pd/CeO2 showed a Pd completed oxidized and with a mean particle size of 1.7 nm, which seemed to be unfavorable for both, alcohols dehydrogenation and TCE HDC. On PdRh/CeO2, active metals presented a mean particle size of 2.7 nm and more reduced metallic species, with ratios of Rh(0)/Rh(+δ) = 0.67 and Pd(0)/Pd(+δ) = 0.28, which showed to be suitable features for the TCE HDC. On the other hand, TGA results suggested some deposition of NaCl residues over the catalyst surfaces. Thus, the new reaction system using PdRh/CeO2 allowed for the degradation of high concentrations of the chlorinated compound by using in situ hydrogen liquid donors in a reaction at room temperature and pressure. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Liquefaction of solid carbonaceous material with catalyst recycle

    Science.gov (United States)

    Gupta, Avinash; Greene, Marvin I.

    1992-01-01

    In the two stage liquefaction of a carbonaceous solid such as coal wherein coal is liquefied in a first stage in the presence of a liquefaction solvent and the first stage effluent is hydrogenated in the presence of a supported hydrogenation catalyst in a second stage, catalyst which has been previously employed in the second stage and comminuted to a particle size distribution equivalent to 100% passing through U.S. 100 Mesh, is passed to the first stage to improve the overall operation.

  8. Non-PGM cell catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Colon-Mercado, H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Elvington, M. [Savannah River Consulting, Aiken, SC (United States); Ganesan, P. [Savannah River Consulting, Aiken, SC (United States)

    2017-09-27

    A unique approach has been developed to probe the non-PGM catalyst active site for the Oxygen Reduction Reaction (ORR) for PEMFCs. Iron based functionalities have been engineered into a variety of catalysts to evaluate their impact on activity for the ORR. A series of high surface area catalysts were synthesized and the impact of the chemical structure on the electrochemical and electrocatalytic properties was investigated. Elemental and surface analyses of the prepared catalysts reveal the incorporation of iron in a targeted and controlled manner. A high surface area framework catalyst was prepared that shows exceptional activity, comparable to state-of-the-art materials. The results of this research project provided critical seed data for the newly awarded ElectroCat project, which focuses on rationally designed framework catalysts for the oxygen reduction reaction.

  9. Hyperfine interactions in metallic catalysts

    International Nuclear Information System (INIS)

    Saitovitch, Henrique; Silva, Paulo R.J.; Passos, Fabio B.

    2005-01-01

    Heterogeneous catalysts are of fundamental importance in several modern chemical processes. The characterization of catalysts is an issue of very present interest as it can provide a better understanding of the fundamental aspects of the catalytic phenomena, thus helping in the development of more efficient catalysts. In order to extend and improve the characterization of catalysts, new and less conventional methods are being applied, such as nuclear spectroscopies. In this paper we focus on the application of angular correlation, with can be used to resolve different local environments of probe atoms in solids and can be applied, as shown here, in the characterization of heterogeneous catalysts. A brief theoretical introduction is given and experimental results related to catalytic systems of alumina and niobia-supported Pt-In and Pd-In catalysts are presented. (author)

  10. Formation of Platinum Catalyst on Carbon Black Using an In‐Liquid Plasma Method for Fuel Cells

    Directory of Open Access Journals (Sweden)

    Yoshiyuki Show

    2017-01-01

    Full Text Available Platinum (Pt catalyst was formed on the surface of carbon black using an in‐liquid plasma method. The formed Pt catalyst showed the average particle size of 4.1 nm. This Pt catalyst was applied to a polymer electrolyte membrane fuel cell (PEMFC. The PEMFC showed an open voltage of 0.85 V and a maximum output power density of 216 mW/cm2.

  11. XAFS analysis of unsupported $MoS_{2}$ catalysts prepared by two methods

    CERN Document Server

    Matsubayashi, N; Imamura, M; Yoshimura, Y; Nishijima, A; Calais, C; Geantet, C

    1999-01-01

    Structural analysis by XAFS method was applied to two kinds of unsupported molybdenum disulfide catalysts. Assuming a structural model consisting of crystalline and non-crystalline parts, curve fitting analysis was performed for the $9 catalysts. The residual XAFS after subtraction of the crystalline contribution showed that the structure of the non-crystalline part was significantly different between the catalysts prepared by the two methods. It was suggested that $9 EXAFS would give the average size of the micro-domains, while other methods such as TEM and TPR would give the size of macro- domains. (6 refs).

  12. Development of GREET Catalyst Module

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhichao [Argonne National Lab. (ANL), Argonne, IL (United States); Benavides, Pahola T. [Argonne National Lab. (ANL), Argonne, IL (United States); Dunn, Jennifer B. [Argonne National Lab. (ANL), Argonne, IL (United States); Cronauer, Donald C. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2015-09-01

    In this report, we develop energy and material flows for the production of five different catalysts (tar reforming, alcohol synthesis, Zeolite Socony Mobil-5 [ZSM-5], Mo/Co/ γ-Al2O3, and Pt/ γ-Al2O3) and two chemicals (olivine, dimethyl ether of polyethylene glycol [DEPG]). These compounds and catalysts are now included in the Greenhouse Gases, Regulated Emissions and Energy Use in Transportation (GREET™) catalyst module.

  13. Oxygen-reducing catalyst layer

    Science.gov (United States)

    O'Brien, Dennis P [Maplewood, MN; Schmoeckel, Alison K [Stillwater, MN; Vernstrom, George D [Cottage Grove, MN; Atanasoski, Radoslav [Edina, MN; Wood, Thomas E [Stillwater, MN; Yang, Ruizhi [Halifax, CA; Easton, E Bradley [Halifax, CA; Dahn, Jeffrey R [Hubley, CA; O'Neill, David G [Lake Elmo, MN

    2011-03-22

    An oxygen-reducing catalyst layer, and a method of making the oxygen-reducing catalyst layer, where the oxygen-reducing catalyst layer includes a catalytic material film disposed on a substrate with the use of physical vapor deposition and thermal treatment. The catalytic material film includes a transition metal that is substantially free of platinum. At least one of the physical vapor deposition and the thermal treatment is performed in a processing environment comprising a nitrogen-containing gas.

  14. Catalyst systems and uses thereof

    Science.gov (United States)

    Ozkan, Umit S [Worthington, OH; Holmgreen, Erik M [Columbus, OH; Yung, Matthew M [Columbus, OH

    2012-07-24

    A method of carbon monoxide (CO) removal comprises providing an oxidation catalyst comprising cobalt supported on an inorganic oxide. The method further comprises feeding a gaseous stream comprising CO, and oxygen (O.sub.2) to the catalyst system, and removing CO from the gaseous stream by oxidizing the CO to carbon dioxide (CO.sub.2) in the presence of the oxidation catalyst at a temperature between about 20 to about 200.degree. C.

  15. Effects of Catalyst Preparation on Hydrocarbon Product Distribution in Hydrocracking of the Fischer-Tropsch Product with Low Pt-Loaded Catalysts

    Directory of Open Access Journals (Sweden)

    Toshiaki Hanaoka

    2015-11-01

    Full Text Available For the effective production of hydrocarbon liquid fuel in the hydrocracking of the Fischer-Tropsch (FT product, the catalytic performance of Pt-loaded catalysts with low Pt content was investigated using an autoclave at 250 °C, an initial H2 pressure of 0.5 MPa, and a reaction time of 1 h. A screening study using Pt-loaded catalysts with a Pt content of 0.1 wt. % indicated that zeolite supports were more favorable for jet fuel (carbon numbers 9–15 production than amorphous oxide supports. The small particle size of the supported Pt particles and the high amount of medium acid sites for the supports led to higher performance of the Pt-loaded zeolite catalysts. In the hydrocracking reaction over Pt catalysts using the zeolite support with the high amount of medium acid sites, the yields of the corresponding jet fuel at 0.02 and 0.1 wt. % were almost the same. Pt-loaded catalysts with a Pt content of 0.02 wt. % were prepared using water-in-oil (w/o microemulsions and their particle size was controlled between 1.0 and 2.6 nm. While the yield of the corresponding jet fuel was independent of Pt particle size, smaller Pt particles typically promoted the production of lighter hydrocarbons.

  16. DEVELOPMENT OF ATTRITION RESISTANT IRON-BASED FISCHER-TROPSCH CATALYSTS

    International Nuclear Information System (INIS)

    Adeyinka A. Adeyiga

    2001-01-01

    The Fischer-Tropsch (F-T) reaction provides a way of converting coal-derived synthesis gas (CO+H 2 ) to liquid fuels. Since the reaction is highly exothermic, one of the major problems in control of the reaction is heat removal. Recent work has shown that the use of slurry bubble column reactors (SBCRs) can largely solve this problem. The use of iron-based catalysts is attractive not only due to their low cost and ready availability, but also due to their high water-gas shift activity which makes it possible to use these catalysts with low H 2 /CO ratios. However, a serious problem with use of Fe catalysts in a SBCR is their tendency to undergo attrition. This can cause fouling/plugging of downstream filters and equipment, makes the separation of catalyst from the oil/wax product very difficult if not impossible, and results in a steady loss of catalyst from the reactor. Recently, fundamental understanding of physical attrition is being addressed by incorporating suitable binders into the catalyst recipe. This has resulted in the preparation of a spray dried Fe-based catalyst having aps of 70 mm with high attrition resistance. This Fe-based attrition resistant, active and selective catalyst gave 95% CO conversion through 125 hours of testing in a fixed-bed at 270 C, 1.48 MPa, H 2 /CO=0.67 and 2.0 NL/g-cat/h with C 5 + selectivity of >78% and methane selectivity of <5%. However, further development of the catalyst is needed to address the chemical attrition due to phase changes that any Fe-catalyst goes through potentially causing internal stresses within the particle and resulting in weakening, spalling or cracking. The objective of this research is to develop robust iron-based Fischer-Tropsch catalysts that have suitable activity, selectivity and stability to be used in the slurry bubble column reactor. Specifically we aim to develop to: (i) improve the performance and preparation procedure of the high activity, high attrition resistant, high alpha iron

  17. Asymmetric pair distribution functions in catalysts

    DEFF Research Database (Denmark)

    Clausen, B. S.; Nørskov, Jens Kehlet

    2000-01-01

    it has been realized that often there is a need to use an improved EXAFS data analysis compared to the simple harmonic approach which works well for well-defined bulk structures. This is due to the fact that catalysts contain highly dispersed or disordered structures with pair distribution functions...... of asymmetric pair distribution functions for nano-sized particles and how they influence the structural parameters obtained from the standard data analysis. An alternative method, which takes into account deviations from the Gaussian pair distribution function typically used in the analysis of EXAFS spectra......, will be described. The method is based on an analysis of the pair distribution functions derived from molecular dynamics simulations of small metal particles and its reliability is demonstrated by comparing structural parameters obtained from independent X-ray diffraction experiments....

  18. Reuse of Hydrotreating Spent Catalyst

    International Nuclear Information System (INIS)

    Habib, A.M.; Menoufy, M.F.; Amhed, S.H.

    2004-01-01

    All hydro treating catalysts used in petroleum refining processes gradually lose activity through coking, poisoning by metal, sulfur or halides or lose surface area from sintering at high process temperatures. Waste hydrotreating catalyst, which have been used in re-refining of waste lube oil at Alexandria Petroleum Company (after 5 years lifetime) compared with the same fresh catalyst were used in the present work. Studies are conducted on partial extraction of the active metals of spent catalyst (Mo and Ni) using three leaching solvents,4% oxidized oxalic acid, 10% aqueous sodium hydroxide and 10% citric acid. The leaching experiments are conducting on the de coked extrude [un crushed] spent catalyst samples. These steps are carried out in order to rejuvenate the spent catalyst to be reused in other reactions. The results indicated that 4% oxidized oxalic acid leaching solution gave total metal removal 45.6 for de coked catalyst samples while NaOH gave 35% and citric acid gave 31.9 % The oxidized leaching agent was the most efficient leaching solvent to facilitate the metal removal, and the rejuvenated catalyst was characterized by the unchanged crystalline phase The rejuvenated catalyst was applied for hydrodesulfurization (HDS) of vacuum gas oil as a feedstock, under different hydrogen pressure 20-80 bar in order to compare its HDS activity

  19. Mixed Alcohol Synthesis Catalyst Screening

    Energy Technology Data Exchange (ETDEWEB)

    Gerber, Mark A.; White, James F.; Stevens, Don J.

    2007-09-03

    National Renewable Energy Laboratory (NREL) and Pacific Northwest National Laboratory (PNNL) are conducting research to investigate the feasibility of producing mixed alcohols from biomass-derived synthesis gas (syngas). PNNL is tasked with obtaining commercially available or preparing promising mixed-alcohol catalysts and screening them in a laboratory-scale reactor system. Commercially available catalysts and the most promising experimental catalysts are provided to NREL for testing using a slipstream from a pilot-scale biomass gasifier. From the standpoint of producing C2+ alcohols as the major product, it appears that the rhodium catalyst is the best choice in terms of both selectivity and space-time yield (STY). However, unless the rhodium catalyst can be improved to provide minimally acceptable STYs for commercial operation, mixed alcohol synthesis will involve significant production of other liquid coproducts. The modified Fischer-Tropsch catalyst shows the most promise for providing both an acceptable selectivity to C2+ alcohols and total liquid STY. However, further optimization of the Fischer-Tropsch catalysts to improve selectivity to higher alcohols is highly desired. Selection of a preferred catalyst will likely entail a decision on the preferred coproduct slate. No other catalysts tested appear amenable to the significant improvements needed for acceptable STYs.

  20. Advanced new technologies for residue upgrading

    International Nuclear Information System (INIS)

    Gillis, D.

    1997-01-01

    Viewgraphs summarizing UOP technologies for residue are provided. The upgrading technologies include: (1) Aquaconversion, (2) the Discriminatory Destructive Distillation process (3D), and (3) the RCD uniflex process. The Aquaconversion process is based on catalytic hydrovisbreaking. It makes use of a homogeneous (liquid phase) catalyst. The hydrogen is derived from water. The advantages of this process are improved residue stability and quality at higher conversion levels, high synthetic crude yields, low operational complexity, reduced transportation costs. The 3D process is a unique carbon rejection contaminant removal process which can process whole crudes through viscous residues. FCC type equipment is used. Performance characteristics and advantages of the process were highlighted. The RCD uniflex process makes use of proven fixed bed and ebullated bed technologies in a new process configuration in which the fixed bed system is located upstream of the ebullated bed system. In this process, the catalyst volume increases exponentially with increasing processing severity. Performance characteristics, design features, benefits and development progress to date are described. 1 tab., 21 figs

  1. CARBON COATED (CARBONOUS) CATALYST IN EBULLATED BED REACTOR FOR PRODUCTION OF OXYGENATED CHEMICALS FROM SYNGAS/CO2

    Energy Technology Data Exchange (ETDEWEB)

    Peizheng Zhou

    2001-10-26

    There are a number of exothermic chemical reactions which might benefit from the temperature control and freedom from catalyst fouling provided by the ebullated bed reactor technology. A particularly promising area is production of oxygenated chemicals, such as alcohols and ethers, from synthesis gas, which can be economically produced from coal or biomass. The ebullated bed operation requires that the small-diameter ({approx}1/32 inch) catalyst particles have enough mechanical strength to avoid loss by attrition. However, all of the State Of The Art (SOTA) catalysts and advanced catalysts for the purpose are low in mechanical strength. The patented carbon-coated catalyst technology developed in our laboratory converts catalyst particles with low mechanical strength to strong catalysts suitable for ebullated bed application. This R&D program is concerned with the modification on the mechanical strength of the SOTA and advanced catalysts so that the ebullated bed technology can be utilized to produce valuable oxygenated chemicals from syngas/CO{sub 2} efficiently and economically. The objective of this R&D program is to study the technical and economic feasibility of selective production of high-value oxygenated chemicals from synthesis gas and CO{sub 2} mixed feed in an ebullated bed reactor using carbon-coated catalyst particles.

  2. Microstructural observation of fuel cell catalyst inks by Cryo-SEM and Cryo-TEM.

    Science.gov (United States)

    Shimanuki, Junichi; Takahashi, Shinichi; Tohma, Hajime; Ohma, Atsushi; Ishihara, Ayumi; Ito, Yoshiko; Nishino, Yuri; Miyazawa, Atsuo

    2017-06-01

    In order to improve the electricity generation performance of fuel cell electric vehicles, it is necessary to optimize the microstructure of the catalyst layer of a polymer electrolyte fuel cell. The catalyst layer is formed by a wet coating process using catalyst inks. Therefore, it is very important to observe the microstructure of the catalyst ink. In this study, the morphology of carbon-supported platinum (Pt/C) particles in catalyst inks with a different solvent composition was investigated by cryogenic scanning electron microscopy (cryo-SEM). In addition, the morphology of the ionomer, which presumably influences the formation of agglomerated Pt/C particles in a catalyst ink, was investigated by cryogenic transmission electron microscopy (cryo-TEM). The results of a cryo-SEM observation revealed that the agglomerated Pt/C particles tended to become coarser with a higher 1-propanol (NPA) weight fraction. The results of a cryo-TEM observation indicated that the actual ionomer dispersion in a catalyst ink formed a network structure different from that of the ionomer in the solvent. © The Author 2017. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  3. Rapid and Efficient Collection of Platinum from Karstedt's Catalyst Solution via Ligands-Exchange-Induced Assembly.

    Science.gov (United States)

    Yang, Gonghua; Wei, Yanlong; Huang, Zhenzhu; Hu, Jiwen; Liu, Guojun; Ou, Ming; Lin, Shudong; Tu, Yuanyuan

    2018-02-21

    Reported herein is a novel strategy for the rapid and efficient collection of platinum from Karstedt's catalyst solution. By taking advantage of a ligand-exchange reaction between alkynols and the 1,3-divinyltetramethyldisiloxane ligand (M Vi M Vi ) that coordinated with platinum (Pt(0)), the Karstedt's catalyst particles with a size of approximately 2.5 ± 0.7 nm could be reconstructed and assembled into larger particles with a size of 150 ± 35 nm due to the hydrogen bonding between the hydroxyl groups of the alkynol. In addition, because the silicone-soluble M Vi M Vi ligand of the Karstedt's catalyst was replaced by water-soluble alkynol ligands, the resultant large particles were readily dispersed in water, resulting in rapid, efficient, and complete collection of platinum from the Karstedt's catalyst solutions with platinum concentrations in the range from ∼20 000 to 0.05 ppm. Our current strategy not only was used for the rapid and efficient collection of platinum from the Karstedt's catalyst solutions, but it also enabled the precise evaluation of the platinum content in the Karstedt's catalysts, even if this platinum content was extremely low (i.e., 0.05 ppm). Moreover, these platinum specimens that were efficiently collected from the Karstedt's catalyst solutions could be directly used for the evaluation of platinum without the need for pretreatment processes, such as calcination and digestion with hydrofluoric acid, that were traditionally used prior to testing via inductively coupled plasma mass spectrometry in conventional methods.

  4. FIB-SEM Tomography Probes the Mesoscale Pore Space of an Individual Catalytic Cracking Particle

    NARCIS (Netherlands)

    de Winter, D. A. Matthijs; Meirer, Florian; Weckhuysen, Bert M.

    2016-01-01

    The overall performance of a catalyst particle strongly depends on the ability of mass transport through its pore space. Characterizing the three-dimensional structure of the macro- and mesopore space of a catalyst particle and establishing a correlation with transport efficiency is an essential

  5. Mass transport models for a single particle in gas phase propylene polymerization

    NARCIS (Netherlands)

    Parasu Veera, U.

    2003-01-01

    Olefin polymerisation on heterogeneous catalysts is gaining importance due to widening of the polymer properties window. The supported active catalyst on the heterogeneous particle reacts with the monomer and produces polymer. Polymeric flow (PF) model is relatively simple and assume that particle

  6. Catalyst Deactivation Simulation Through Carbon Deposition in Carbon Dioxide Reforming over Ni/CaO-Al2O3 Catalyst

    Directory of Open Access Journals (Sweden)

    Istadi Istadi

    2011-11-01

    Full Text Available Major problem in CO2 reforming of methane (CORM process is coke formation which is a carbonaceous residue that can physically cover active sites of a catalyst surface and leads to catalyst deactivation. A key to develop a more coke-resistant catalyst lies in a better understanding of the methane reforming mechanism at a molecular level. Therefore, this paper is aimed to simulate a micro-kinetic approach in order to calculate coking rate in CORM reaction. Rates of encapsulating and filamentous carbon formation are also included. The simulation results show that the studied catalyst has a high activity, and the rate of carbon formation is relatively low. This micro-kinetic modeling approach can be used as a tool to better understand the catalyst deactivation phenomena in reaction via carbon deposition. Copyright © 2011 BCREC UNDIP. All rights reserved.(Received: 10th May 2011; Revised: 16th August 2011; Accepted: 27th August 2011[How to Cite: I. Istadi, D.D. Anggoro, N.A.S. Amin, and D.H.W. Ling. (2011. Catalyst Deactivation Simulation Through Carbon Deposition in Carbon Dioxide Reforming over Ni/CaO-Al2O3 Catalyst. Bulletin of Chemical Reaction Engineering & Catalysis, 6 (2: 129-136. doi:10.9767/bcrec.6.2.1213.129-136][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.6.2.1213.129-136 || or local:  http://ejournal.undip.ac.id/index.php/bcrec/article/view/1213 ] | View in  |  

  7. Electrocatalytic Reduction-oxidation of Chlorinated Phenols using a Nanostructured Pd-Fe Modified Graphene Catalyst

    International Nuclear Information System (INIS)

    Shi, Qin; Wang, Hui; Liu, Shaolei; Pang, Lei; Bian, Zhaoyong

    2015-01-01

    A Pd-Fe modified graphene (Pd-Fe/G) catalyst was prepared by the Hummers oxidation method and bimetallic co-deposition method. The catalyst was then characterized by various characterization techniques and its electrochemical property toward the electrocatalytic reduction-oxidation of chlorinated phenols was investigated by using cyclic voltammetry and differential pulse voltammetry. The results of the characterization show that the Pd-Fe/G catalyst in which the weight proportion of Pd and Fe is 1:1 has an optimal surface performance. The diameter of the Pd-Fe particles is approximately 5.2 ± 0.3 nm, with a uniform distribution on the supporting graphene. This is smaller than the Pd particles of a Pd-modified graphene (Pd/G) catalyst. The Pd-Fe/G catalyst shows a higher electrocatalytic activity than the Pd/G catalyst for reductive dechlorination when feeding with hydrogen gas. The reductive peak potentials of −0.188 V, −0.836 V and −0.956 V in the DPV curves are attributed to the dechlorination of ortho-Cl, meta-Cl, and para-Cl in 2-chlorophenol, 3-chlorophenol and 4-chlorophenol, respectively. In accordance with an analysis of the frontier orbital theory, the order of ease of dechlorination with Pd-Fe/G catalyst is 2-chlorophenol > 3-chlorophenol > 4-chlorophenol. The Pd-Fe/G catalyst has a greater activity than the Pd/G catalyst in accelerating the two-electron reduction of O 2 to H 2 O 2 , which is attributed to the higher current of the reduction peak at approximately −0.40 V when feeding with oxygen gas. Therefore, the Pd-Fe/G catalyst exhibits a higher electrocatalytic activity than the Pd/G catalyst for the reductive dechlorination and acceleration of the two-electron reduction of O 2 to H 2 O 2 .

  8. REACTOR FILLED WITH CATALYST MATERIAL, AND CATALYST THEREFOR

    NARCIS (Netherlands)

    Sie, S.T.

    1995-01-01

    Abstract of WO 9521691 (A1) Described is a reactor (1) at least partially filled with catalyst granules (11), which is intended for catalytically reacting at least one gas and at least one liquid with each other. According to the invention the catalyst granules (11) are collected in agglomerates

  9. Influence of cobalt precursor and of its decomposition on the synthesis of cobalt nano-particles on silica for the optimization of the Fischer-Tropsch catalysts; Influence du precurseur de cobalt et de sa decomposition sur la synthese de nanoparticules de cobalt sur silice dans le cadre de l'optimisation des catalyseurs Fischer-Tropsch

    Energy Technology Data Exchange (ETDEWEB)

    Girardon, J.S.; Khodakov, A.Y.; Constant-Griboval, A. [Universite des sciences et technologies de Lille, Lab. de catalyse de Lille, UMR 8010, 59 - Villeneuve D' Ascq (France)

    2004-07-01

    In order to synthesize Fischer-Tropsch catalysts more active and selective in heavy hydrocarbons, the understanding at the molecular level of the chemical processes which occur during synthesis is a strategic stake. This work is based in one hand on the use of different cobalt precursors (acetate (Ac) and nitrate (N)) and in another hand on the influence of the decomposition temperature of these precursors on the formation of cobalt nano-particles. An UV-visible study shows that the impregnated cobalt coming from the two types of precursors is in an octahedral environment before its decomposition. The XRD, UV-visible and XANES-EXAFS studies show, after decomposition in air (400 C, 5 hours), that the sample prepared from cobalt nitrate (N400) presents a Co{sub 3}O{sub 4} phase. This phase is not detected in the case of the cobalt acetate (Ac400). These observations are in agreement with the results of the catalytic tests which show that the solid N400 is eight times more than the solid Ac400. A softer decomposition at 170 C during 70 hours of the cobalt acetate (Ac170) has allowed to minimize the formation of cobalt silicate for Co{sub 3}O{sub 4} and to increase of more than three times the catalytic activity. In the case of cobalt nitrate, the XRD analysis of the solids obtained after a softer decomposition (150 C and 100 C) has revealed a decrease of the size of the cobalt nano-particles. The catalytic conversion remains the same than with N400 but a better C{sub 5}{sup +} selectivity is observed. (O.M.)

  10. Particle Analysis in Forensic Science.

    Science.gov (United States)

    Bisbing, R E; Schneck, W M

    2006-07-01

    Microscopic trace evidence includes particles from many sources such as biologicals, soil, building materials, metals, explosives, gunshot residues, and cosmetics. The particles are identified by morphological analysis, microscopy, and chemical analysis. Their identity is confirmed by comparison with reference materials or other comparison samples. The probative value of particles of forensic interest depends on their nature and the circumstances of their presence. Copyright © 2006 Central Police University.

  11. Novel Reforming Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Pfefferle, Lisa D; Haller, Gary L

    2012-10-16

    Aqueous phase reforming is useful for processing oxygenated hydrocarbons to hydrogen and other more useful products. Current processing is hampered by the fact that oxide based catalysts are not stable under high temperature hydrothermal conditions. Silica in the form of structured MCM-41 is thermally a more stable support for Co and Ni than conventional high surface area amorphous silica but hydrothermal stability is not demonstrated. Carbon nanotube supports, in contrast, are highly stable under hydrothermal reaction conditions. In this project we show that carbon nanotubes are stable high activity/selectivity supports for the conversion of ethylene glycol to hydrogen.

  12. A Catalyst for Change

    DEFF Research Database (Denmark)

    Lønsmann, Dorte

    2017-01-01

    into in a process that hinges on new members functioning as tools for management to bring about the desired change. The article shows that while the newcomer is used as a catalyst for increased use of English and for the creation of a 'global mindset,' she is at the same time socialized into the existing Danish...... for changing language practices toward more English, with the ultimate aim of creating a 'global mindset' in the organization. Language socialization in a transient multilingual setting is shown to focus on and assign positive value to new linguistic norms that experienced members are socialized...

  13. In-situ characterization of heterogeneous catalysts

    CERN Document Server

    Rodriguez, Jose A; Chupas, Peter J

    2013-01-01

    Helps researchers develop new catalysts for sustainable fuel and chemical production Reviewing the latest developments in the field, this book explores the in-situ characterization of heterogeneous catalysts, enabling readers to take full advantage of the sophisticated techniques used to study heterogeneous catalysts and reaction mechanisms. In using these techniques, readers can learn to improve the selectivity and the performance of catalysts and how to prepare catalysts as efficiently as possible, with minimum waste. In-situ Characterization of Heterogeneous Catalysts feat

  14. Electron beam application for regeneration of catalysts used in refinery cracking units

    International Nuclear Information System (INIS)

    Kondo, Fernando Mantovani; Duarte, Celina Lopes; Sato, Ivone Mulako; Salvador, Vera Lucia Ribeiro; Calvo, Wilson Aparecido Parejo

    2013-01-01

    A catalyst is a substance that alters the rate of a reaction. The process of catalysis is essential to the modern day manufacturing industry, mainly in Fluid Catalytic Cracking Process (FCC) units. However, long-term exploitation of oil and gas processing catalysts leads to formation of carbon-and sulfur-containing structures of coke and dense products on the catalyst surface. They block reactive catalyst sites and reduce the catalytic activity. The main advantage of radiation processing by electron beam (EB) and gamma rays is chain cracking reaction in crude oil. Otherwise, under exposure to ionic radiation, considerable structure modification of equilibrium silica-alumina catalyst from FCC process may occur, in addition to the removal of impurities. The conditions applied in the irradiation range (20-150 kGy) of gamma rays and electron beam were not sufficient to alter the structure of the catalyst, whether for removal of the contaminant nickel, a major contaminant of the FCC catalyst, either to rupture of the crystalline structure either for the future reutilization of chemical elements. Attenuated Total Reflectance - Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Energy Dispersive X-Ray Fluorescence Spectrometry (EDXRFS) analysis were used to characterize and evaluate effects of radiation processing on equilibrium catalysts purification. To evaluate and comprehend the reactive catalyst sites, Scanning Electron Microscopy (SEM) and particle size distribution analyses were carried out. (author)

  15. Durable Catalysts for High Temperature Proton Exchange Membrane Fuel Cells

    DEFF Research Database (Denmark)

    significant attention in recent years because of its potential advantages such as high CO tolerance, easy cooling, better heat utilization and possible integration with fuel processing units. However, the high temperature obviously aggravates the carbon corrosion and catalyst degradation. Based on thermally......Durability of proton exchange membrane fuel cells (PEMFCs) is recognized as one of the most important issues to be addressed before the commercialization. The failure mechanisms are not well understood, however, degradation of carbon supported noble metal catalysts is identified as a major failure...... corrosion, in turn, triggers the agglomeration of platinum particles resulting in reduction of the active surface area and catalytic activity. This is a major mechanism of the catalyst degradation and a key challenge to the PEMFC long-term durability. High temperature PEMFC, on the other hand, has attached...

  16. The behaviour of a single catalyst pellet for the selective hydrogenation of ethyne in ethene

    NARCIS (Netherlands)

    Bos, A.N.R.; Bos, A.N.R.; Hof, E.; Kuper, W.; Westerterp, K.R.

    1993-01-01

    The steady-state and dynamic behaviour of a single Pd---Al2O3 catalyst particle is studied for the selective hydrogenation of ethyne in the presence of ethene, without addition of carbon monoxide. The particle-to-gas heat transfer in the reactor is characterized. During selective hydrogenation, not

  17. Towards ‘greener’ catalyst manufacture: Reduction of wastewater from the preparation of Cu/ZnO/Al2O3 methanol synthesis catalysts

    NARCIS (Netherlands)

    Prieto, G.; de Jong, K.P.|info:eu-repo/dai/nl/06885580X; de Jongh, P.E.|info:eu-repo/dai/nl/186125372

    2013-01-01

    The generation of large volumes of nitrate-containing wastewater is a major issue in the industrial production of solid catalysts such as Cu/ZnO/Al2O3 employed in methanol synthesis. Extensive washing with water is needed to remove nitrate (and sodium) residues in the as-precipitated metal

  18. Conversion of direct process high-boiling residue to monosilanes

    Science.gov (United States)

    Brinson, Jonathan Ashley; Crum, Bruce Robert; Jarvis, Jr., Robert Frank

    2000-01-01

    A process for the production of monosilanes from the high-boiling residue resulting from the reaction of hydrogen chloride with silicon metalloid in a process typically referred to as the "direct process." The process comprises contacting a high-boiling residue resulting from the reaction of hydrogen chloride and silicon metalloid, with hydrogen gas in the presence of a catalytic amount of aluminum trichloride effective in promoting conversion of the high-boiling residue to monosilanes. The present process results in conversion of the high-boiling residue to monosilanes. At least a portion of the aluminum trichloride catalyst required for conduct of the process may be formed in situ during conduct of the direct process and isolation of the high-boiling residue.

  19. Controllable synthesis of Co3O4 nanocrystals as efficient catalysts for oxygen reduction reaction

    Science.gov (United States)

    Li, Baoying; Zhang, Yihe; Du, Ruifeng; Liu, Lei; Yu, Xuelian

    2018-03-01

    The electrochemical oxygen reduction reaction (ORR) has received great attention due to its importance in fuel cells and metal–air batteries. Here, we present a simple approach to prepare non-noble metal catalyst-Co3O4 nanocrystals (NCs). The particle size and shape were simply controlled by different types and concentrations of metal precursor. Furthermore, different sizes and shapes of Co3O4 NCs are explored as electrocatalysts for ORR, and it has been observed that particles with a similar shape, and smaller particle size led to greater catalytic current densities because of the greater surface area. For particles with a comparable size, the shape or crystalline structure governed the activity of the electrocatalytic reactions. Most importantly, the 9 nm-Co3O4 were demonstrated to act as low-cost catalysts for the ORR with a similar performance to that of Pt catalysts.

  20. Flame spray synthesis of CoMo/Al2O3 hydrotreating catalysts

    DEFF Research Database (Denmark)

    Høj, Martin; Linde, Kasper; Hansen, Thomas Klint

    2011-01-01

    The first alumina supported and unsupported cobalt molybdenum hydrotreating catalysts have been prepared by one-step flame spray pyrolysis (FSP) by spraying and combusting tris(acetylacetonato)aluminum, cobalt 2-ethylhexanoate and molybdenum 2-ethylhexaoate dissolved in toluene. The oxide particles...... agglomerates with 5–10nm primary particles were produced. As the molybdenum loading on the alumina was increased from 8 to 32wt.% and for the unsupported reference the primary particle size increased to up to 20nm and the morphology became more irregular due to primary particle sintering and aggregation.......After activation by sulfidation the activity of the catalysts were measured for the three hydrotreating reactions hydrodesulfurization, hydrodenitrogenation and hydrogenation using a model oil containing dibenzothiophene, indole and naphthalene in n-heptane solution. The best catalyst was the FSP-produced material...

  1. The Enhanced Catalytic Performance and Stability of Rh/γ-Al2O3 Catalyst Synthesized by Atomic Layer Deposition (ALD for Methane Dry Reforming

    Directory of Open Access Journals (Sweden)

    Yunlin Li

    2018-01-01

    Full Text Available Rh/γ-Al2O3 catalysts were synthesized by both incipient wetness impregnation (IWI and atomic layer deposition (ALD. The TEM images of the two catalysts showed that the catalyst from ALD had smaller particle size, and narrower size distribution. The surface chemical states of both catalysts were investigated by both XPS and X-ray Absorption Near Edge Structure (XANES, and the catalyst from IWI had higher concentration of Rh3+ than that from ALD. The catalytic performance of both catalysts was tested in the dry reforming of methane reaction. The catalyst from ALD showed a higher conversion and selectivity than that from IWI. The stability testing results indicated that the catalyst from ALD showed similar stability to that from IWI at 500 °C, but higher stability at 800 °C.

  2. The Enhanced Catalytic Performance and Stability of Rh/γ-Al₂O₃ Catalyst Synthesized by Atomic Layer Deposition (ALD) for Methane Dry Reforming.

    Science.gov (United States)

    Li, Yunlin; Jiang, Jing; Zhu, Chaosheng; Li, Lili; Li, Quanliang; Ding, Yongjie; Yang, Weijie

    2018-01-22

    Rh/γ-Al₂O₃ catalysts were synthesized by both incipient wetness impregnation (IWI) and atomic layer deposition (ALD). The TEM images of the two catalysts showed that the catalyst from ALD had smaller particle size, and narrower size distribution. The surface chemical states of both catalysts were investigated by both XPS and X-ray Absorption Near Edge Structure (XANES), and the catalyst from IWI had higher concentration of Rh 3+ than that from ALD. The catalytic performance of both catalysts was tested in the dry reforming of methane reaction. The catalyst from ALD showed a higher conversion and selectivity than that from IWI. The stability testing results indicated that the catalyst from ALD showed similar stability to that from IWI at 500 °C, but higher stability at 800 °C.

  3. Catalyst and its diameter dependent growth kinetics of CVD grown GaN nanowires

    International Nuclear Information System (INIS)

    Samanta, Chandan; Chander, D. Sathish; Ramkumar, J.; Dhamodaran, S.

    2012-01-01

    Graphical abstract: GaN nanowires with controlled diameter and aspect ratio has been grown using a simple CVD technique. The growth kinetics of CVD grown nanowires investigated in detail for different catalysts and their diameters. A critical diameter important to distinguish the growth regimes has been discussed in detail. The results are important which demonstrates the growth of diameter and aspect ratio controlled GaN nanowires and also understand their growth kinetics. Highlights: ► Controlled diameter and aspect ratio of GaN nanowires achieved in simple CVD reactor. ► Nanowire growth kinetics for different catalyst and its diameters were understood. ► Adatoms vapor pressure inside reactor plays a crucial role in growth kinetics. ► Diffusion along nanowire sidewalls dominate for gold and nickel catalysts. ► Gibbs–Thomson effect dominates for palladium catalyst. -- Abstract: GaN nanowires were grown using chemical vapor deposition with controlled aspect ratio. The catalyst and catalyst-diameter dependent growth kinetics is investigated in detail. We first discuss gold catalyst diameter dependent growth kinetics and subsequently compare with nickel and palladium catalyst. For different diameters of gold catalyst there was hardly any variation in the length of the nanowires but for other catalysts with different diameter a strong length variation of the nanowires was observed. We calculated the critical diameter dependence on adatoms pressure inside the reactor and inside the catalytic particle. This gives an increasing trend in critical diameter as per the order gold, nickel and palladium for the current set of experimental conditions. Based on the critical diameter, with gold and nickel catalyst the nanowire growth was understood to be governed by limited surface diffusion of adatoms and by Gibbs–Thomson effect for the palladium catalyst.

  4. Relating FTS Catalyst Properties to Performance

    Science.gov (United States)

    Ma, Wenping; Ramana Rao Pendyala, Venkat; Gao, Pei; Jermwongratanachai, Thani; Jacobs, Gary; Davis, Burton H.

    2016-01-01

    than in the unpromoted catalyst. Nevertheless, the Co clusters remained slightly larger, on average, in comparison with the unpromoted 15%Co/Al2O3 reference catalyst. None of the promoted catalysts (i.e., with Cd, In, or Sn) exhibited surface Co0 site densities higher than that of the unpromoted catalyst. In activity testing, the activities were even much lower than what was expected from the H2-TPD results. Two possible explanations were proposed: (1) the promoters may be located on the surfaces of cobalt particles, blocking surface Co0 but being able to desorb hydrogen or (2) the promoters may facilitate Co oxidation during FTS, as previously observed by Huffman and coworkers when K was added to cobalt catalysts.

  5. Cure Schedule for Stycast 2651/Catalyst 11.

    Energy Technology Data Exchange (ETDEWEB)

    Kropka, Jamie Michael [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); McCoy, John D. [New Mexico Inst. of Mining and Technology, Socorro, NM (United States)

    2017-11-01

    The Henkel technical data sheet (TDS) for Stycast 2651/Catalyst 11 lists three alternate cure schedules for the material, each of which would result in a different state of reaction and different material properties. Here, a cure schedule that attains full reaction of the material is defined. The use of this cure schedule will eliminate variance in material properties due to changes in the cure state of the material, and the cure schedule will serve as the method to make material prior to characterizing properties. The following recommendation was motivated by (1) a desire to cure at a single temperature for ease of manufacture and (2) a desire to keep the cure temperature low (to minimize residual stress build-up associated with the cooldown from the cure temperature to room temperature) without excessively limiting the cure reaction due to vitrification (i.e., material glass transition temperature, Tg, exceeding cure temperature).

  6. Ring opening metathesis polymerization catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Grubbs, R.H.; Johnson, L.K.; Novak, B.M.; Hillmyer, M.; Benedicto, A.; France, M.; Nguyen, S.T. [California Institute of Technology, Pasadena, CA (United States)

    1993-12-31

    Over the past eight years, a number of new catalysts for the ring opening metathesis polymerization of cyclic olefins have been developed. These catalysts are simple organometallic complexes containing metal carbon multiple bonds that in most cases polymerize olefins by a living process. These catalysts have been used to prepare a family of near monodispersed and structurally homogeneous polymers, a series of telechelic polymers with controlled molecular weight and functionality and triblock polymers with segments with potentially interesting electronic properties. A series of new group VIII catalysts are being developed that allow a wide range of functionality to be incorporated into the polymer side chains. The same catalysts can also be used in the synthesis of fine chemicals.

  7. Supported molten-metal catalysts

    Science.gov (United States)

    Datta, Ravindra; Singh, Ajeet; Halasz, Istvan; Serban, Manuela

    2001-01-01

    An entirely new class of catalysts called supported molten-metal catalysts, SMMC, which can replace some of the existing precious metal catalysts used in the production of fuels, commodity chemicals, and fine chemicals, as well as in combating pollution. SMMC are based on supporting ultra-thin films or micro-droplets of the relatively low-melting (metals and semimetals from groups 1, 12, 13, 14, 15 and 16, of the periodic table, or their alloys and intermetallic compounds, on porous refractory supports, much like supported microcrystallites of the traditional solid metal catalysts. It thus provides orders of magnitude higher surface area than is obtainable in conventional reactors containing molten metals in pool form and also avoids corrosion. These have so far been the chief stumbling blocks in the application of molten metal catalysts.

  8. C-H activation on rhodium: reaction mechanism and the role of carbonaceous residues

    International Nuclear Information System (INIS)

    Cogen, J.M.; Maier, W.F.

    1986-01-01

    Evidence for two C-H activation mechanisms, the oxidative addition of a single C-H bond and the concerted oxidative addition of two adjacent C-H bonds, is presented. The two mechanisms show different sensitivity to surface structure or particle size. While the first process (E/sub a/ ∼ 21 kcal/mol) is insensitive to the hydrocarbon structure, the second process (E/sub a/ ∼ 5-9 kcal/mol) is sensitive to the hydrocarbon structure. C-H activation is found to be 0.6 order in hexane and zero order in deuterium, which is consistent with oxidative addition as the rate-determining step. The d 2 maximum obtained by H/D exchange of linear alkanes on Rh results from surface olefins, as indicated by high-resolution deuterium NMR. Evidence against the participation of carbonaceous residues in the H/D exchange process is presented, indicating that carbonaceous material is not part of the active site. Two types of carbonaceous residues are detected. One forms at lower temperatures and does not interfere with the reaction; the other forms at higher temperatures and acts to poison the catalyst

  9. Tailoring Silica-alumina Supported Pt-Pd As Poison Tolerant Catalyst For Aromatics Hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Yanzhe; Gutierrez, Oliver Y.; Haller, Gary L.; Colby, Robert J.; Kabius, Bernd C.; Rob van Veen, J. A.; Jentys, Andreas; Lercher, Johannes A.

    2013-08-01

    The tailoring of the physicochemical and catalytic properties of mono- and bimetallic Pt-Pd catalysts supported on amorphous silica-alumina is studied. Electron energy loss spectroscopy and extended X-ray absorption fine structure analyses indicated that bimetallic Pt-Pd and relatively large monometallic Pd particles were formed, whereas the X-ray absorption near edge structure provided direct evidence for the electronic deficiency of the Pt atoms. The heterogeneous distribution of metal particles was also shown by high resolution transmission electron microscopy. The average structure of the bimetallic particles (Pt-rich core and Pd-rich shell) and the presence of Pd particles led to surface Pd enrichment, which was independently shown by IR spectra of adsorbed CO. The specific metal distribution, average size, and surface composition of the Pt-Pd particles depend to a large extent on the metal precursors. In the presence of NH3 ligands, Pt-Pd particles with a fairly homogeneous bulk and surface metal distribution were formed. Also high Lewis acid site concentration of the carrier leads to more homogeneous bimetallic particles. All catalysts were active for the hydrogenation of tetralin in the absence and presence of quinoline and dibenzothiophene (DBT). Monometallic Pt catalysts had the highest hydrogenation activity in poison-free and quinoline-containing feed. When DBT was present, bimetallic Pt-Pd catalysts with the most homogenous metal distribution showed the highest activity. The higher resistance of bimetallic catalysts towards sulfur poisoning compared to their monometallic Pt counterparts results from the weakened metal-sulfur bond on the electron deficient Pt atoms. Thus, increasing the fraction of electron deficient Pt on the surface of the bimetallic particles increases the efficiency of the catalyst in the presence of sulfur.

  10. Iron Contamination Mechanism and Reaction Performance Research on FCC Catalyst

    Directory of Open Access Journals (Sweden)

    Zhaoyong Liu

    2015-01-01

    Full Text Available FCC (Fluid Catalytic Cracking catalyst iron poisoning would not only influence units’ product slate; when the poisoning is serious, it could also jeopardize FCC catalysts’ fluidization in reaction-regeneration system and further cause bad influences on units’ stable operation. Under catalytic cracking reaction conditions, large amount of iron nanonodules is formed on the seriously iron contaminated catalyst due to exothermic reaction. These nodules intensify the attrition between catalyst particles and generate plenty of fines which severely influence units’ smooth running. A dense layer could be formed on the catalysts’ surface after iron contamination and the dense layer stops reactants to diffuse to inner structures of catalyst. This causes extremely negative effects on catalyst’s heavy oil conversion ability and could greatly cut down gasoline yield while increasing yields of dry gas, coke, and slurry largely. Research shows that catalyst’s reaction performance would be severely deteriorated when iron content in E-cat (equilibrium catalyst exceeds 8000 μg/g.

  11. Magnetic solid acid catalyst for biodiesel synthesis from waste oil

    International Nuclear Information System (INIS)

    Li, Junqiao; Liang, Xuezheng

    2017-01-01

    Highlights: • A new magnetic solid acid has been synthesized. • A new solid acid showed high activities for biodiesel synthesis from waste oils under mild condition. • A simple magnetic separation and high stability were the key properties of the new catalyst. - Abstract: A new magnetic solid acid catalyst was synthesized by immobilizing an ionic liquid precursor obtained from (3-aminopropyl)trimethoxysilane onto a magnetic core. The magnetic solid acid catalyst has a core–shell structure, and the acid sites on the shell were easily accessible to reactants. The catalytic activities of the magnetic solid acid were investigated by biodiesel synthesis from waste oils. The solid acid exhibited a higher activity than traditional acid catalysts and the ionic liquid precursor. The core–shell structure and magnetic attraction between the particles provided strong ionic interactions, resulting in the high activity and stability. The main characteristics of the magnetic solid acid catalyst were as follows: easily accessible acidic sites, simple magnetic separation and high waste oil utilization.

  12. Iron Contamination Mechanism and Reaction Performance Research on FCC Catalyst

    International Nuclear Information System (INIS)

    Liu, Z.; Zhang, Z.; Yang, C.; Liu, Z.; Zhang, Z.; Liu, P.; Zhai, J.

    2015-01-01

    FCC (Fluid Catalytic Cracking) catalyst iron poisoning would not only influence units’ product slate; when the poisoning is serious, it could also jeopardize FCC catalysts’ fluidization in reaction-regeneration system and further cause bad influences on units’ stable operation. Under catalytic cracking reaction conditions, large amount of iron nano nodules is formed on the seriously iron contaminated catalyst due to exothermic reaction. These nodules intensify the attrition between catalyst particles and generate plenty of fines which severely influence units’ smooth running. A dense layer could be formed on the catalysts’ surface after iron contamination and the dense layer stops reactants to diffuse to inner structures of catalyst. This causes extremely negative effects on catalyst’s heavy oil conversion ability and could greatly cut down gasoline yield while increasing yields of dry gas, coke, and slurry largely. Research shows that catalyst’s reaction performance would be severely deteriorated when iron content in E-cat (equilibrium catalyst) exceeds 8000 μg/g.

  13. Production of syngas by ethanol reforming on Ni catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Catapan, Rafael C.; Oliveira, Amir A.M.; Donadel, Karina; Oliveira, Antonio Pedro N.; Rambo, Carlos R. [Federal University of Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. of Mechanical Engineering. Lab. of Combustion and Thermal Systems Engineering], Emails: catapan@labcet.ufsc.br, donadel@emc.ufsc.br, pedronovaes@emc.ufsc.br, rambo@enq.ufsc.br; Oliveira, Therezinha Maria N.; Wagner, Theodoro M. [Universidade da Regiao de Joinville, SC (Brazil). Campus Universitario Bom Retiro], E-mails: tnovais@univille.br, theowag@terra.com.br

    2010-07-01

    In the recent literature, attention has been directed to the development of noble metals based catalysts for the ethanol reforming. However, the high costs and low availability of noble metals, e.g. platinum, as a resource justify the development of alternatives technologically, economically and environmentally viable such as Ni-based catalysts. Here, the thermal decomposition, partial oxidation and steam reforming of ethanol over SiO{sub 2} supported Ni was studied in a packed bed reactor in the 673 - 973 K temperature range at 1 atm. The catalyst was produced from 10% NiO, 5% of bentonite and 85% (wt.) of natural amorphous silica fibers (NASF). Scanning Electron Microscopy (SEM) evaluation revealed that particles of Ni were homogeneously distributed over the NASF. The X-ray diffraction (XRD) patterns did not show peaks related to silicates in all spectra, which indicates that there is no, apparently, interaction between the nickel catalysts and SiO{sub 2} or devitrification The reactions of ethanol on this catalyst occurs mainly by the dehydrogenation reaction generating acetaldehyde. Further, CH{sub 3}CHO is decomposed to CH{sub 4} and CO. In parallel to this route, ethanol is dehydrated producing ethylene, which is successively dehydrogenated in Ni sites generating carbon on the surface. Also, carbon can be produced by consecutive dehydrogenation of CH{sub 4}. Both reactions contribute to increase the production of H{sub 2} to values higher than those predicted by the thermodynamic equilibrium. (author)

  14. Analysis of the spallation residues and the associated particles in the reaction Fe+p at 1 GeV per nucleon; Analyse des residus de spallation et des particules associees dans la reaction Fe+p a 1 GeV par nucleon

    Energy Technology Data Exchange (ETDEWEB)

    Le Gentil, E

    2006-09-15

    SPALADIN is a new type of spallation experiment that has been carried out at the GSI accelerator facility (Germany) in order to improve the modelling of the spallation reaction. This experiment is based on the coincidence measurement in inverse kinematics of the spallation residues and the de-excitation fragments. This work presents the analysis of Fe{sup 56} + p reaction at 1 GeV per nucleon. Results on cross-sections and heavy residue velocity spectra are compared to previous data and enabled us to characterize the setup. Most of the element production cross-sections have been obtained with an uncertainty below 10 per cent. In the particular case of helium, its production cross-section has been measured to be {sigma}(1 GeV) = (598 {+-} 67) mb. The knowledge of this cross-section is important to assess the irradiation damage undergone by the window separating the accelerator from the target. The study of the de-excitation of the pre-fragment shows that the evaporation of light particles (Z {<=} 2) is the main way of de-excitation whatever the collision centrality. However, the de-excitation through the emission of intermediate mass fragments is observed in 5% of the events and most of these events correspond to a very asymmetric binary breaking. The velocity distributions of light residues (with regards to the mass of the projectile) show a significant disagreement with the average velocities predicted by spallation codes. (A.C.)

  15. Metal catalysts for steam reforming of tar derived from the gasification of lignocellulosic biomass.

    Science.gov (United States)

    Li, Dalin; Tamura, Masazumi; Nakagawa, Yoshinao; Tomishige, Keiichi

    2015-02-01

    Biomass gasification is one of the most important technologies for the conversion of biomass to electricity, fuels, and chemicals. The main obstacle preventing the commercial application of this technology is the presence of tar in the product gas. Catalytic reforming of tar appears a promising approach to remove tar and supported metal catalysts are among the most effective catalysts. Nevertheless, improvement of catalytic performances including activity, stability, resistance to coke deposition and aggregation of metal particles, as well as catalyst regenerability is greatly needed. This review focuses on the design and catalysis of supported metal catalysts for the removal of tar in the gasification of biomass. The recent development of metal catalysts including Rh, Ni, Co, and their alloys for steam reforming of biomass tar and tar model compounds is introduced. The role of metal species, support materials, promoters, and their interfaces is described. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Effect of catalyst properties and operating conditions on hydroprocessing high metals feeds

    Energy Technology Data Exchange (ETDEWEB)

    Pazos, J.M.; Gonzalez, J.C.; Saluzar-Gullen, A.J.

    1983-10-01

    Catalytic hydroprocessing of high metals heavy oils, containing over 480 ppm Ni + V, was carried out in trickle bed pilot units. The analyses of the used catalysts (coke, metals content, and vanadium distribution) were correlated with the deactivation runs. The deactivation by coke is very much dependent on the catalyst physical properties (mean pore diameter), rather than on the chemical properties, and on the nature of the feed. As metals removal is a diffusion-controlled reaction, catalysts and operating conditions that increase the Thiele modulus, e.g., high activity and small pore catalysts, high hydrogen pressures and temperatures, show a stronger deactivation by feed metals. In this case, most of the vanadium was deposited in the outer edge of the catalyst particle. Unconventional vanadium profiles along the reactor length were obtained under certain conditions. Based on these data, a kinetic model was proposed which considers that demetallization is a complex reaction that occurs through a series of consecutive and parallel reactions.

  17. Nano-magnetic catalyst KF/CaO-Fe3O4 for biodiesel production

    International Nuclear Information System (INIS)

    Hu, Shengyang; Guan, Yanping; Wang, Yun; Han, Heyou

    2011-01-01

    A nano-magnetic catalyst KF/CaO-Fe 3 O 4 was prepared by a facile impregnation method. The magnetic property of the catalyst was studied by vibrating sample magnetometer (VSM). The results demonstrated that the catalyst was ferromagnetic, and it could be recovered by magnetic separation. The nano-magnetic catalyst was also characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and BET surface area analyzer. It was found that the catalyst possessed a unique porous structure with an average particle diameter of ca. 50 nm. Besides, the factors affecting biodiesel yield were investigated, and a desired fatty acid methyl esters yield over 95% was obtained under the optimal conditions.

  18. Bimetallic Pt-Ru Nanoparticle Catalyst for Hydrogen Peroxide Detection

    Directory of Open Access Journals (Sweden)

    Metini Janyasupab

    2011-01-01

    Full Text Available A bimetallic Pt-Ru nanoparticle catalyst was prepared and characterized for the enhancement of hydrogen peroxide (H2O2 detection in biosensing applications. The particles were synthesized via sodium borohydride reduction, with low heat treatment, and characterized by TEM and HRTEM. The chemical composition analyses were performed by EDX. The bimetallic particle diameters ranged from 2 to 12 nm, with an average of 4.5 nm. The Pt-Ru catalyst exhibited an improved performance at low overpotential (+0.2 V versus Ag/AgCl reference electrode in H2O2 detection, suggesting a sensitivity value of 78.95 μA⋅mM-1 (or 402.1 μA⋅mM-1⋅cm-2 which was 30% higher than that for the single Pt catalyst. The major contribution of this enhancement comes from the stronger oxygen adsorption on Ru metal. The Pt-Ru catalyst also showed a more stable signal at the high overpotential (+0.4 V versus Ag/AgCl, providing better accuracy in the detection of H2O2.

  19. Fresh tar (from biomass gasification) destruction with downstream catalysts: comparison of their intrinsic activity with a realistic kinetic model

    Energy Technology Data Exchange (ETDEWEB)

    Corella, J.; Narvaez, I.; Orio, A. [Complutense Univ. of Madrid (Spain). Dept. of Chemical Engineering

    1996-12-31

    A model for fresh tar destruction over catalysts placed downstream a biomass gasifier is presented. It includes the stoichio-metry and the calculation of the kinetic constants for the tar destruction. Catalysts studied include commercial Ni steam reforming catalysts and calcinated dolomites. Kinetic constants for tar destruction are calculated for several particle sizes, times- on-stream and temperatures of the catalyst and equivalence ratios in the gasifier. Such intrinsic kinetic constants allow a rigorous or scientific comparison of solids and conditions to be used in an advanced gasification process. (orig.) 4 refs.

  20. Mesoporous Silica Supported Au Nanoparticles with Controlled Size as Efficient Heterogeneous Catalyst for Aerobic Oxidation of Alcohols

    Directory of Open Access Journals (Sweden)

    Xuefeng Chu

    2015-01-01

    Full Text Available A series of Au catalysts with different sizes were synthesized and employed on amine group functionalized ordered mesoporous silica solid supports as catalyst for the aerobic oxidation of various alcohols. The mesoporous silica of MCM-41 supported Au nanoparticles (Au-1 exhibited the smallest particle size at ~1.8 nm with superior catalytic activities owing to the confinement effect of the mesoporous channels. Au-1 catalyst is also very stable and reusable under aerobic condition. Therefore, this presented work would obviously provide us a platform for synthesizing more size-controlled metal catalysts to improve the catalytic performances.

  1. Preparation and study of IrO2/SiC–Si supported anode catalyst for high temperature PEM steam electrolysers

    DEFF Research Database (Denmark)

    Nikiforov, Aleksey; Tomás García, Antonio Luis; Petrushina, Irina

    2011-01-01

    A novel catalyst material for oxygen evolution electrodes was prepared and characterised by different techniques. IrO2 supported on a SiC–Si composite was synthesised by the Adams fusion method. XRD and nitrogen adsorption experiments showed an influence of the support on the surface properties...... of the IrO2 particles, affecting the IrO2 particle size. The prepared catalysts were electrochemically characterised by cyclic voltammetry experiments at 25,80,120 and 150 °C. In accordance with the observed variation in particle size, a support loading of up to 20% improved the activity of the catalyst....... Powder conductivity measurements were also performed, which showed the influence of the support particles in the packing of IrO2 particles, perhaps favouring the formation of channels and pores between particles, thus increasing the catalyst utilisation....

  2. Landfill Mining of Shredder Residues

    DEFF Research Database (Denmark)

    Hansen, Jette Bjerre; Hyks, Jiri; Shabeer Ahmed, Nassera

    In Denmark, shredder residues (SR) are classified as hazardous waste and until January 2012 the all SR were landfilled. It is estimated that more than 1.8 million tons of SR have been landfilled in mono cells. This paper describes investigations conducted at two Danish landfills. SR were excavated...... from the landfills and size fractionated in order to recover potential resources such as metal and energy and to reduce the amounts of SR left for re-landfilling. Based on the results it is estimated that 60-70% of the SR excavated could be recovered in terms of materials or energy. Only a fraction...... with particle size less than 5 mm needs to be re-landfilled at least until suitable techniques are available for recovery of materials with small particle sizes....

  3. CO Sensing Performance of a Micro Thermoelectric Gas Sensor with AuPtPd/SnO₂ Catalyst and Effects of a Double Catalyst Structure with Pt/α-Al₂O₃.

    Science.gov (United States)

    Goto, Tomoyo; Itoh, Toshio; Akamatsu, Takafumi; Shin, Woosuck

    2015-12-15

    The CO sensing properties of a micro thermoelectric gas sensor (micro-TGS) with a double AuPtPd/SnO₂ and Pt/α-Al₂O₃ catalyst were investigated. While several nanometer sized Pt and Pd particles were uniformly dispersed on SnO₂, the Au particles were aggregated as particles measuring >10 nm in diameter. In situ diffuse reflectance Fourier transform Infrared spectroscopy (DRIFT) analysis of the catalyst showed a CO adsorption peak on Pt and Pd, but no clear peak corresponding to the interaction between CO and Au was detected. Up to 200 °C, CO combustion was more temperature dependent than that of H₂, while H₂ combustion was activated by repeated exposure to H₂ gas during the periodic gas test. Selective CO sensing of the micro-TGS against H₂ was attempted using a double catalyst structure with 0.3-30 wt% Pt/α-Al₂O₃ as a counterpart combustion catalyst. The sensor output of the micro-TGS decreased with increasing Pt content in the Pt/α-Al₂O₃ catalyst, by cancelling out the combustion heat from the AuPtPd/SnO₂ catalyst. In addition, the AuPtPd/SnO₂ and 0.3 wt% Pt/α-Al₂O₃ double catalyst sensor showed good and selective CO detection. We therefore demonstrated that our micro-TGS with double catalyst structure is useful for controlling the gas selectivity of CO against H₂.

  4. Synthesis and characterization of nanosized Cu/ZnO catalyst by polyol method.

    Science.gov (United States)

    Altinçekiç, Tuba Gürkaynak; Boz, Ismail; Aktürk, Selçuk

    2008-02-01

    Nanosized catalysts composed of metallic copper supported on zinc oxide have been synthesized by the polyol process. Average crystallite size of copper was between 10 and 45 nm. Cu/ZnO catalyst particles were characterized by various techniques, such as X-ray Powder Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Selected Area Electron Diffraction (SAED), and dynamic light scattering analysis (DLS).

  5. Development of GREET Catalyst Module

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhichao [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division; Dunn, Jennifer B. [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division; Cronauer, Donald C. [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division

    2014-09-01

    Catalysts are critical inputs for many pathways that convert biomass into biofuels. Energy consumption and greenhouse gas (GHG) emissions during the production of catalysts and chemical inputs influence the life-cycle energy consumption, and GHG emissions of biofuels and need to be considered in biofuel life-cycle analysis (LCA). In this report, we develop energy and material flows for the production of three different catalysts (tar reforming, alcohol synthesis, Zeolite Socony Mobil-5 [ZSM-5]) and two chemicals (olivine, dimethyl ether of polyethylene glycol [DEPG]). These compounds and catalysts are now included in the Greenhouse Gases, Regulated Emissions and Energy Use in Transportation (GREET™) catalyst module. They were selected because they are consumed in existing U.S. Department of Energy (DOE) analyses of biofuel processes. For example, a thermochemical ethanol production pathway (indirect gasification and mixed alcohol synthesis) developed by the National Renewable Energy Laboratory (NREL) uses olivine, DEPG, and tar reforming and alcohol synthesis catalysts (Dutta et al., 2011). ZSM-5 can be used in biofuel production pathways such as catalytic upgrading of sugars into hydrocarbons (Biddy and Jones, 2013). Other uses for these compounds and catalysts are certainly possible. In this report, we document the data sources and methodology we used to develop material and energy flows for the catalysts and compounds in the GREET catalyst module. In Section 2 we focus on compounds used in the model Dutta et al. (2011) developed. In Section 3, we report material and energy flows associated with ZSM-5 production. Finally, in Section 4, we report results.

  6. Efficient low-temperature soot combustion by bimetallic Ag-Cu/SBA-15 catalysts.

    Science.gov (United States)

    Wen, Zhaojun; Duan, Xinping; Hu, Menglin; Cao, Yanning; Ye, Linmin; Jiang, Lilong; Yuan, Youzhu

    2018-02-01

    In this study, the effects of copper (Cu) additive on the catalytic performance of Ag/SBA-15 in complete soot combustion were investigated. The soot combustion performance of bimetallic Ag-Cu/SBA-15 catalysts was higher than that of monometallic Ag and Cu catalysts. The optimum catalytic performance was acquired with the 5Ag 1 -Cu 0.1 /SBA-15 catalyst, on which the soot combustion starts at T ig =225°C with a T 50 =285°C. The temperature for 50% of soot combustion was lower than that of conventional Ag-based catalysts to more than 50°C (Aneggi et al., 2009). Physicochemical characterizations of the catalysts indicated that addition of Cu into Ag could form smaller bimetallic Ag-Cu nanolloy particles, downsizing the mean particle size from 3.7nm in monometallic catalyst to 2.6nm in bimetallic Ag-Cu catalyst. Further experiments revealed that Ag and Cu species elicited synergistic effects, subsequently increasing the content of surface active oxygen species. As a result, the structure modifications of Ag by the addition of Cu strongly intensified the catalytic performance. Copyright © 2017. Published by Elsevier B.V.

  7. Tunable synthetic approaches for the optimization of nanostructured fuel cell catalysts: An overview

    Directory of Open Access Journals (Sweden)

    Bönnemann H.

    2004-01-01

    Full Text Available Highly active nanostructured pluri-metal catalysts for fuel cell applications can be obtained by designing synthetic protocol where the particle size, metal composition and morphology can be readily tailored. Tunable synthesis relates to combining the various synthetic methodologies available for generating nanostructured metal catalysts with desired catalytic properties. Herein, we discuss some of these synthetic methodologies which were developed to combine the advantages of each pathway in generating efficient fuel cell catalysts and to learn how the composition and morphology of the metals be fine tuned.

  8. SCR activity of conformed CuOX/ZrO2-SO4 catalysts

    DEFF Research Database (Denmark)

    Rasmussen, Søren Birk; Yates, M.; Due-Hansen, Johannes

    2010-01-01

    CuOX/ZrO2-SO4 catalysts have been synthesised as conformed materials with the use of sepiolite as agglomerant and the performance in the NH3-SCR reaction with relation to biomass fired boiler units have been studied. The optimal Cu-loading of the catalysts is 3 wt.% CuO, both in terms of activity...... and selectivity. This catalyst constitutes a possible solution for NO removal in biomass-related applications, since it posses mainly Lewis acid sites, and therefore might be less subjected to deactivation by potassium containing fly ash particle produced during biomass combustion....

  9. Surface treated carbon catalysts produced from waste tires for fatty acids to biofuel conversion

    Energy Technology Data Exchange (ETDEWEB)

    Hood, Zachary D.; Adhikari, Shiba P.; Wright, Marcus W.; Lachgar, Abdessadek; Li, Yunchao; Naskar, Amit K.; Paranthaman, Mariappan Parans

    2018-02-06

    A method of making solid acid catalysts includes the step of sulfonating waste tire pieces in a first sulfonation step. The sulfonated waste tire pieces are pyrolyzed to produce carbon composite pieces having a pore size less than 10 nm. The carbon composite pieces are then ground to produce carbon composite powders having a size less than 50 .mu.m. The carbon composite particles are sulfonated in a second sulfonation step to produce sulfonated solid acid catalysts. A method of making biofuels and solid acid catalysts are also disclosed.

  10. Chalcogen catalysts for polymer electrolyte fuel cell

    Science.gov (United States)

    Alonso-Vante, Nicolas [Buxerolles, FR; Zelenay, Piotr [Los Alamos, NM; Choi, Jong-Ho [Los Alamos, NM; Wieckowski, Andrzej [Champaign, IL; Cao, Dianxue [Urbana, IL

    2009-09-15

    A methanol-tolerant cathode catalyst and a membrane electrode assembly for fuel cells that includes such a cathode catalyst. The cathode catalyst includes a support having at least one transition metal in elemental form and a chalcogen disposed on the support. Methods of making the cathode catalyst and membrane electrode assembly are also described.

  11. Increasing the lifetime of fuel cell catalysts

    NARCIS (Netherlands)

    Latsuzbaia, R.

    2015-01-01

    In this thesis, I discuss a novel idea of fuel cell catalyst regeneration to increase lifetime of the PEM fuel cell electrode/catalyst operation and, therefore, reduce the catalyst costs. As many of the catalyst degradation mechanisms are difficult to avoid, the regeneration is alternative option to

  12. Impeded solid state reactions and transformations in ceramic catalysts supports and catalysts

    Directory of Open Access Journals (Sweden)

    Ernő E. Kiss

    2012-12-01

    Full Text Available Impeded chemical reactions and impeded polymorphous transformation in materials are discussed, as desired effects, for stabilization of ceramic catalyst supports and ceramic based catalysts. This paper gives a short overview about the possibilities of slowing down the aging processes in ceramic catalyst supports and catalysts. Special attention is given to alumina and titania based catalysts.

  13. Direct Fabrication of Carbon Nanotubes STM Tips by Liquid Catalyst-Assisted Microwave Plasma-Enhanced Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    Fa-Kuei Tung

    2009-01-01

    Full Text Available Direct and facile method to make carbon nanotube (CNT tips for scanning tunneling microscopy (STM is presented. Cobalt (Co particles, as catalysts, are electrochemically deposited on the apex of tungsten (W STM tip for CNT growth. It is found that the quantity of Co particles is well controlled by applied DC voltage, concentration of catalyst solution, and deposition time. Using optimum growth condition, CNTs are successfully synthesized on the tip apex by catalyst-assisted microwave-enhanced chemical vapor deposition (CA-MPECVD. A HOPG surface is clearly observed at an atomic scale using the present CNT-STM tip.

  14. Enhanced Dry Reforming of Methane on Ni and Ni-Pt Catalysts Synthesized by Atomic Layer Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Gould, Troy D.; Montemore, Matthew M.; Lubers, Alia M.; Ellis, Lucas D.; Weimer, Alan; Falconer, John L.; Medlin, James W.

    2015-02-25

    Atomic layer deposition (ALD) was used to deposit Ni and Pt on alumina supports to form monometallic and bimetallic catalysts with initial particle sizes of 1–2.4 nm. The ALD catalysts were more active (per mass of metal) than catalysts prepared by incipient wetness (IW) for dry reforming of methane (DRM), and they did not form carbon whiskers during reaction due to their sufficiently small size. Catalysts modified by Pt ALD had higher rates of reaction per mass of metal and inhibited coking, whereas NiPt catalysts synthesized by IW still formed carbon whiskers. Temperature-programmed reduction of Ni catalysts modified by Pt ALD indicated the presence of bimetallic interaction. Density functional theory calculations suggested that under reaction conditions, the NiPt surfaces form Ni-terminated surfaces that are associated with higher DRM rates (due to their C and O adsorption energies, as well as the CO formation and CH4 dissociation energies).

  15. Nano-Engineered Catalysts for Direct Methanol Fuel Cells

    Science.gov (United States)

    Myung, Nosang; Narayanan, Sekharipuram; Wiberg, Dean

    2008-01-01

    Nano-engineered catalysts, and a method of fabricating them, have been developed in a continuing effort to improve the performances of direct methanol fuel cells as candidate power sources to supplant primary and secondary batteries in a variety of portable electronic products. In order to realize the potential for high energy densities (as much as 1.5 W h/g) of direct methanol fuel cells, it will be necessary to optimize the chemical compositions and geometric configurations of catalyst layers and electrode structures. High performance can be achieved when catalyst particles and electrode structures have the necessary small feature sizes (typically of the order of nanometers), large surface areas, optimal metal compositions, high porosity, and hydrophobicity. The present method involves electrodeposition of one or more catalytic metal(s) or a catalytic-metal/polytetrafluoroethylene nanocomposite on an alumina nanotemplate. The alumina nanotemplate is then dissolved, leaving the desired metal or metal/polytetrafluoroethylene-composite catalyst layer. Unlike some prior methods of making fine metal catalysts, this method does not involve processing at elevated temperature; all processing can be done at room temperature. In addition, this method involves fewer steps and is more amenable to scaling up for mass production. Alumina nanotemplates are porous alumina membranes that have been fabricated, variously, by anodizing either pure aluminum or aluminum that has been deposited on silicon by electronbeam evaporation. The diameters of the pores (7 to 300 nm), areal densities of pores (as much as 7 x 10(exp 10)sq cm), and lengths of pores (up to about 100 nm) can be tailored by selection of fabrication conditions. In a given case, the catalytic metal, catalytic metal alloy, or catalytic metal/ polytetrafluoroethylene composite is electrodeposited in the pores of the alumina nanotemplate. The dimensions of the pores, together with the electrodeposition conditions

  16. Characterization of a surface modified carbon cryogel and a carbon supported Pt catalyst

    Directory of Open Access Journals (Sweden)

    BILJANA M. BABIĆ

    2007-08-01

    Full Text Available A carbon cryogel, synthesized by carbonization of a resorcinol/formaldehyde cryogel and oxidized in nitric acid, was used as catalyst support for Pt nano-particles. The Pt/C catalyst was prepared by a modified polyol synthesis method in an ethylene glycol (EG solution. Characterization by nitrogen adsorption showed that the carbon cryogel support and the Pt/C catalyst were mesoporous materials with high specific surface areas (SBET > 400 m2 g-1 and large mesoporous volumes. X-Ray diffraction of the catalyst demonstrated the successful reduction of the Pt precursor to metallic form. TEM Images of the Pt/C catalyst and Pt particle size distribution showed that the mean Pt particle size was about 3.3 nm. Cyclic voltammetry (CV experiments at various scan rates (from 2 to 200 mV s-1 were performed in 0.5 mol dm-3 HClO4 solution. The large capacitance of the oxidized carbon cryogel electrode, which arises from a combination of the double-layer capacitance and pseudocapacitance, associated with the participation of surface redox-type reactions was demonstrated. For the oxidized carbon cryogel, the total specific capacitance determined by 1/C vs. ν0.5 extrapolation method was found to be 386 F g-1. The hydrogen oxidation reaction at the investigated Pt/C catalyst proceeded as an electrochemically reversible, two-electron direct discharge reaction.

  17. Modeling Deactivation of Catalysts for Selective Catalytic Reduction of NOx by KCl Aerosols

    DEFF Research Database (Denmark)

    Olsen, Brian Kjærgaard; Castellino, Francesco; Jensen, Anker Degn

    2017-01-01

    A detailed model for the deactivation of a V2O5–WO3/TiO2-based SCR monolith catalyst by potassium poisoning has been developed and validated. The model accounts for deposition of KCl aerosol particles present in the flue gas on the external catalyst surface, the reaction of the deposited particles...... with the catalyst at the surface of the monolith wall, the transport and accumulation of potassium, bound to Brønsted acid sites, throughout the catalyst wall, and the resulting loss in SCR activity. Using an experimentally measured KCl aerosol size distribution as input, the model can replicate the observed...... deactivation rate of a 3 wt % V2O5-7 wt % WO3/TiO2 monolith catalyst, exposed to a KCl aerosol at 350 °C for about 1000 h, as well as the resulting potassium-to-vanadium molar ratios in the catalyst wall. Simulations show that the particle deposition rate, as well as the deactivation rate, decreases...

  18. Investigation on deactivation and regeneration of a commercial Ni/Al{sub 2}O{sub 3} catalyst in coal volatile decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Li, L.; Ozaki, J.; Morishita, K.; Ida, C.; Takei, M.; Takarada, T. [Gunma Industrial Support Organization, Gumma (Japan)

    2008-09-15

    The deactivation mechanism of a commercial Ni/Al{sub 2}O{sub 3} catalyst used during coal volatile decomposition was investigated by transmission electron microscopy-energy dispersive X-ray spectroscopy (TEMEDS), X-ray diffraction (XRD) and nitrogen adsorption. The existence of carbonous species in the reaction system promoted nickel particle growth during coal volatile decomposition, and subsequent coking from volatile cracking. Throughout the catalyst deactivation tests, coke deposits were observed as encapsulating carbon in the spent catalyst, and nickel particles doubled in size from around 10 to 20 mm. The spent catalyst was regenerated in oxygen at relatively moderate conditions by removing the coke deposits. As a result, the catalyst activity was restored remarkably; 1.7 times the surface area and double pore volume were present in the regenerated catalyst compared to the spent catalyst. Also, the regenerated catalyst showed high activity for coal volatile decomposition. Under catalysis of the regenerated Ni/Al{sub 2}O{sub 3} the tarry material in coal volatile matter could transform much more completely, gaining both high gas yields and high carbon balance. We also found that methanation is structure sensitive to nickel particles. Under the action of the regenerated catalyst, CO formed during coal volatile decomposition could not be further converted into methane, and the product gases provided a higher CO concentration. Noticeably, tar decomposition was confirmed to be less structure sensitive to the nickel particles than CO-methanation.

  19. Pyrolysis of plastic waste using alumina-pumice as catalyst

    International Nuclear Information System (INIS)

    Warnijati, S.; Agra, I.B.; Wibowo, W.

    2000-01-01

    Efforts to convert plastic waste to liquid fuel have been carried out, but the yield was not so promising yet. Various catalysts have been studied to drive the product more to the liquid fuel. In this study, alumina-pumice produced from cheap local materials, was used as catalyst. Solid polyethylene plastic waste was melted in a feed compartment surrounding the tube reactor, and the vapor flowed downward through the catalyst bed which was supported by small glass marbles. Air and water coolers were used to cool and condense the product. Liquid and uncondensable gas were collected in receivers and bottle filled with brine, respectively. The physical properties of a specific liquid product were tested according to the ASTM methods. Liquid and gas products increased with time and temperature, and the rate of liquid and gas formations followed first order reaction. Using 100 g of plastic waste and 40 g of catalyst, the favorable time and temperature of pyrolysis were 105 minutes and 653-673 K, respectively. Under this condition, 86 - 87 % of liquid, 45 - 53 mL/g of gas, and 1% of solid residue were obtained. The quantity of liquid product was higher than the previous work (which was just 70-75 %) and its physical properties were between those of kerosene and diesel oil. The gross heating value of the liquid was 49 796.03 J/g, and the gas burnt with yellow flame and some soot. (Author)

  20. Palladium Loaded on Magnetic Nanoparticles as Efficient and Recyclable Catalyst for the Suzuki- Miyaura Reaction

    Directory of Open Access Journals (Sweden)

    H. Khojasteh

    2015-07-01

    Full Text Available Palladium is the best metal catalyst for Suzuki cross coupling reaction for synthesize of unsymmetrical biaryl compounds. But its high cost limits its application in wide scale. Using of nanoscale particles as active catalytic cites is a good approach for reducing needed noble metal. By loading precious nanoparticles on magnetic nanocores as a support, recycling and reusing of catalyst will be possible. Magnetic nanoparticles have super paramagnetic feature and applying an external magnetic field can collect the supported catalyst from reaction milieu simply. In this work new palladium catalyst immobilized on modified magnetic nanoparticles containing NNO donor atoms were synthesized. Then the catalyst characterized by FT-IR spectroscopy, thermogravimetric analysis, X-ray diffraction and ICP. Prepared catalyst showed high activity in the Suzuki– Miyaura cross-coupling reaction of phenylboronic acid with aryl halides. Activity, Pd loading, reusability and Pd leaching of catalyst were studied. Results showed that the supported catalyst has the advantage to be completely recoverable with the simple application of an external magnetic field.

  1. Pd-Au/C catalysts with different alloying degrees for ethanol oxidation in alkaline media

    International Nuclear Information System (INIS)

    Qin, Yuan-Hang; Li, Yunfeng; Lv, Ren-Liang; Wang, Tie-Lin; Wang, Wei-Guo; Wang, Cun-Wen

    2014-01-01

    High alloyed Pd-Au/C catalyst is prepared through a rate-limiting strategy in water/ethylene glycol solution. Pd/C and low alloyed Pd-Au/C catalysts are prepared with trisodium citrate and sodium borohydride as stabilizing and reducing agents, respectively. Transmission electron microscopy (TEM) shows that the synthesized Pd(Au) particles are well dispersed on the catalysts. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) show that the high alloyed Pd-Au/C catalyst presents a relatively homogenous structure while the low alloyed Pd-Au/C catalyst presents a Pd-rich shell/Au-rich core structure. Electrochemical characterization shows that the low alloyed Pd-Au/C catalyst exhibits the best catalytic activity for ethanol oxidation reaction (EOR) in alkaline media, which could be attributed to its relatively large exposed Pd surface area as compared with the high alloyed Pd-Au/C catalyst due to its Pd-rich shell structure and its enhanced adsorption of OH ads as compared with Pd/C catalyst due to its core-shell structure

  2. Preparation of Modified Red Mud-Supported Fe Catalysts for Hydrogen Production by Catalytic Methane Decomposition

    Directory of Open Access Journals (Sweden)

    Quanrun Liu

    2017-01-01

    Full Text Available A modified red mud- (MRM- supported Fe catalyst (xFe/MRM was prepared using the homogeneous precipitation method and applied to methane decomposition to produce hydrogen. The TEM and SEM-EDX results suggested that the particle sizes of the xFe/MRM catalysts were much smaller than that of raw red mud (RM, and the active metal Fe was evenly distributed over the catalyst structure. Moreover, BET results indicated that the surface areas and pore volumes of the catalysts were significantly improved, and the pore sizes of xFe/MRM were distributed from 5 to 12 nm, which is typical for a mesoporous material. The activities of those catalysts for the catalytic decomposition of methane were studied at atmospheric pressure at a moderate temperature of 650°C; the results showed that the xFe/MRM catalysts were more active than RM and MRM. The methane conversion curves of xFe/MRM catalysts exhibited similar variation tendencies (three-step during the reaction despite different Fe contents, and the loading amount of Fe clearly affected the activity of the catalysts.

  3. Recovery of molybdenum and cobalt powders from spent hydrogenation catalyst

    International Nuclear Information System (INIS)

    Rabah, M.A.; Hewaidy, I.F.; Farghaly, F.E.

    1996-01-01

    Free powders as well as compact shapes of molybdenum and cobalt have been successfully recovered from spent hydrogenation and desulphurization catalysts. A process flow sheet was followed involving crushing, milling, particle sizing, hydrometallurgical acid leaching roasting of the obtained salts in an atmospheric oxygen to obtain the respective oxides. These were reduced by hydrogen gas at 110 degree C and 900 degree C respectively. Parameters affecting the properties of the products and the recovery efficiency value such as acid concentration, particle diameter of the solid catalyst, temperature time under a constant mass flow rate the hydrogen gas, have been investigated. A mixture of concentration.sulphuric and nitric acids (3:1 by volume) achieved adequate recovery of both metals. The latter increased with the increase in acid concentration, time up 10 3 hours and temperature: 100 degree C and with the decrease in particle diameter of the spent catalyst. The PH of the obtained filtrate was adjusted to 2 with ammonia to precipitate insoluble ammonium molybdate and a solution of cobalt sulphate. Cobalt hydroxide can be precipitate from the latter solution at a PH = 7.6 using excess ammonium hydroxide solution. The obtained results showed that the metallic products are technically pure meeting the standard specifications. Compact shapes of molybdenum acquire density values increasing with the increase of the pressing load whereby a maximum density value of 2280 kg/m 3 is attained at 0.75 MPa. Maximum recovery efficiency amounts to 96%. 10 figs., 3 tabs

  4. Thermal Adsorption Processing Of Hydrocarbon Residues

    Directory of Open Access Journals (Sweden)

    Sudad H. Al.

    2017-04-01

    Full Text Available The raw materials of secondary catalytic processes must be pre-refined. Among these refining processes are the deasphalting and demetallization including their thermo adsorption or thermo-contact adsorption variety. In oil processing four main processes of thermo-adsorption refining of hydrocarbon residues are used ART Asphalt Residual Treating - residues deasphaltizing 3D Discriminatory Destructive Distillation developed in the US ACT Adsorption-Contact Treatment and ETCC Express Thermo-Contact Cracking developed in Russia. ART and ACT are processes with absorbers of lift type reactor while 3D and ETCC processes are with an adsorbing reactor having ultra-short contact time of the raw material with the adsorbent. In all these processes refining of hydrocarbon residues is achieved by partial Thermo-destructive transformations of hydrocarbons and hetero-atomic compounds with simultaneous adsorption of the formed on the surface of the adsorbents resins asphaltene and carboids as well as metal- sulphur - and nitro-organic compounds. Demetallized and deasphalted light and heavy gas oils or their mixtures are a quality raw material for secondary deepening refining processes catalytic and hydrogenation cracking etc. since they are characterized by low coking ability and low content of organometallic compounds that lead to irreversible deactivation of the catalysts of these deepening processes.

  5. or Ni-promoted MoS2/SBA-15 catalysts

    Indian Academy of Sciences (India)

    Hydrotreating is a well-known unit operation in a petroleum refinery to reduce sulphur le- vels in naphtha, kerosene, diesel, gas oil and residue.1,2. In this process, employment of highly active catalysts is the most preferred choice among various options to reduce sulphur to ultra low levels. Calculations reveal that to reach ...

  6. Catalytic hydrotreatment of pyrolytic lignins to give alkylphenolics and aromatics using a supported Ru catalyst

    NARCIS (Netherlands)

    Kloekhorst, Arjan; Wildschut, Jelle; Heeres, Hero Jan

    2014-01-01

    The catalytic hydrotreatment of two pyrolytic lignins (pine and forestry residue), obtained from the corresponding fast pyrolysis oils, and organosolv Alcell lignin as a benchmark was explored in a batch set-up using Ru/C as the catalyst (400 degrees C, 4 h, 100 bar initial H-2 pressure). The

  7. Rare earth metals for automotive exhaust catalysts

    International Nuclear Information System (INIS)

    Shinjoh, Hirohumi

    2006-01-01

    The usage of rare earth metals for automotive exhaust catalysts is demonstrated in this paper. Rare earth metals have been widely used in automotive catalysts. In particular, three-way catalysts require the use of ceria compounds as oxygen storage materials, and lanthana as both a stabilizer of alumina and a promoter. The application for diesel catalysts is also illustrated. Effects of inclusion of rare earth metals in automotive catalysts are discussed

  8. Fly ash zeolite catalyst support for Fischer-Tropsch synthesis

    Science.gov (United States)

    Campen, Adam

    This dissertation research aimed at evaluating a fly ash zeolite (FAZ) catalyst support for use in heterogeneous catalytic processes. Gas phase Fischer-Tropsch Synthesis (FTS) over a fixed-bed of the prepared catalyst/FAZ support was identified as an appropriate process for evaluation, by comparison with commercial catalyst supports (silica, alumina, and 13X). Fly ash, obtained from the Wabash River Generating Station, was first characterized using XRD, SEM/EDS, particle size, and nitrogen sorption techniques. Then, a parametric study of a two-step alkali fusion/hydrothermal treatment process for converting fly ash to zeolite frameworks was performed by varying the alkali fusion agent, agent:flyash ratio, fusion temperature, fused ash/water solution, aging time, and crystallization time. The optimal conditions for each were determined to be NaOH, 1.4 g NaOH: 1 g fly ash, 550 °C, 200 g/L, 12 hours, and 48 hours. This robust process was applied to the fly ash to obtain a faujasitic zeolite structure with increased crystallinity (40 %) and surface area (434 m2/g). Following the modification of fly ash to FAZ, ion exchange of H+ for Na+ and cobalt incipient wetness impregnation were used to prepare a FTS catalyst. FTS was performed on the catalysts at 250--300 °C, 300 psi, and with a syngas ratio H2:CO = 2. The HFAZ catalyst support loaded with 11 wt% cobalt resulted in a 75 % carbon selectivity for C5 -- C18 hydrocarbons, while methane and carbon dioxide were limited to 13 and 1 %, respectively. Catalyst characterization was performed by XRD, N2 sorption, TPR, and oxygen pulse titration to provide insight to the behavior of each catalyst. Overall, the HFAZ compared well with silica and 13X supports, and far exceeded the performance of the alumina support under the tested conditions. The successful completion of this research could add value to an underutilized waste product of coal combustion, in the form of catalyst supports in heterogeneous catalytic processes.

  9. Metal Nanoparticle Catalysts for Carbon Nanotube Growth

    Science.gov (United States)

    Pierce, Benjamin F.

    2003-01-01

    Work this summer involved and new and unique process for producing the metal nanoparticle catalysts needed for carbon nanotube (CNT) growth. There are many applications attributed to CNT's, and their properties have deemed them to be a hot spot in research today. Many groups have demonstrated the versatility in CNT's by exploring a wide spectrum of roles that these nanotubes are able to fill. A short list of such promising applications are: nanoscaled electronic circuitry, storage media, chemical sensors, microscope enhancement, and coating reinforcement. Different methods have been used to grow these CNT's. Some examples are laser ablation, flame synthesis, or furnace synthesis. Every single approach requires the presence of a metal catalyst (Fe, Co, and Ni are among the best) that is small enough to produce a CNT. Herein lies the uniqueness of this work. Microemulsions (containing inverse micelles) were used to generate these metal particles for subsequent CNT growth. The goal of this summer work was basically to accomplish as much preliminary work as possible. I strived to pinpoint which variable (experimental process, metal product, substrate, method of application, CVD conditions, etc.) was the determining factor in the results. The resulting SEM images were sufficient for the appropriate comparisons to be made. The future work of this project consists of the optimization of the more promising experimental procedures and further exploration onto what exactly dictated the results.

  10. Biomass processing over gold catalysts

    CERN Document Server

    Simakova, Olga A; Murzin, Dmitry Yu

    2014-01-01

    The book describes the valorization of biomass-derived compounds over gold catalysts. Since biomass is a rich renewable feedstock for diverse platform molecules, including those currently derived from petroleum, the interest in various transformation routes has become intense. Catalytic conversion of biomass is one of the main approaches to improving the economic viability of biorefineries.  In addition, Gold catalysts were found to have outstanding activity and selectivity in many key reactions. This book collects information about transformations of the most promising and important compounds derived from cellulose, hemicelluloses, and woody biomass extractives. Since gold catalysts possess high stability under oxidative conditions, selective oxidation reactions were discussed more thoroughly than other critical reactions such as partial hydrogenation, acetalization, and isomerization. The influence of reaction conditions, the role of the catalyst, and the advantages and disadvantages of using gold are pre...

  11. Development of New Diesel Oxidation and NH3 Slip Catalysts

    DEFF Research Database (Denmark)

    Hansen, Thomas Klint

    .% Pt/Al2O3 catalysts with Pt particles diameters between 1.3 and 18.7 nm. The mass based oxidation activity of CO, C3H6, and NO showed an optimal Pt particle size between 2–4 nm for all three reactions. Based on the turnover frequencies and the distribution of surface atoms of Pt particles...... architecture of the ASC. The resulting Pareto fronts indicate that the optimal catalyst systems with the most potential are those involving mixed layers of AMOX and SCR catalysts, rather than pure layers of AMOX or a top layer of SCR. This is mainly due to the ability of the mixed layers to circumvent N2O...

  12. Probing the different life stages of a fluid catalytic cracking particle with integrated laser and electron microscopy

    NARCIS (Netherlands)

    Karreman, M.A.|info:eu-repo/dai/nl/315886528; Buurmans, I.L.C.|info:eu-repo/dai/nl/31406592X; Agronskaia, A.V.|info:eu-repo/dai/nl/183239830; Geus, J.W.; Gerritsen, H.C.|info:eu-repo/dai/nl/071548777; Weckhuysen, B.M.|info:eu-repo/dai/nl/285484397

    2013-01-01

    While cycling through a fluid catalytic cracking (FCC) unit, the structure and performance of FCC catalyst particles are severely affected. In this study, we set out to characterize the damage to commercial equilibrium catalyst particles, further denoted as ECat samples, and map the different

  13. Kaolin and commercial fcc catalysts in the cracking of loads of polypropylene under refinary conditions

    Directory of Open Access Journals (Sweden)

    A. M. Ribeiro

    2013-12-01

    Full Text Available The efficiency of Commercial FCC catalysts (low, medium and high activities was evaluated by the catalytic cracking process of combined feeds of polypropylene (PP and vaseline, using a microactivity test unit (M.A.T. for the production of fuel fractions (gasoline, diesel and residue. The PP/vaseline loads, at 2.0% and 4.0% wt, were processed under refinery conditions (load/catalyst ratio and temperature of process. For the PP/vaseline load (4.0% wt, the production of the gasoline fraction was favored by all catalysts, while the diesel fraction was favored by PP/vaseline load (2.0% wt, showing a preferential contact of the zeolite external surface with the end of the polymer chains for the occurrence of the catalytic cracking. All the loads produced a bigger quantity of the gaseous products in the presence of highly active commercial FCC catalyst. The improvement in the activity of the commercial FCC catalyst decreased the production of the liquid fractions and increased the quantity of the solid fractions, independent of the concentration of the loads. These results can be related to the difficulty of the polymer chains to access the catalyst acid sites, occurring preferentially end-chain scission at the external surface of the catalyst.

  14. Graphite-supported platinum catalysts: Effects of gas and aqueous phase treatments

    Energy Technology Data Exchange (ETDEWEB)

    Vleeming, J.H.; Kuster, B.F.M.; Marin, G.B. [Eindhoven Univ. of Technology (Netherlands)] [and others

    1997-03-01

    The effects on the platinum particle diameter and the available platinum surface area of a graphite-supported platinum catalyst resulting from pretreatments and from performing a selective oxidation reaction are investigated. In the gas phase considerable catalyst sintering occurs only in the presence of oxygen at 773 K due to extensive carbon burn-off, whereas in an aqueous phase platinum particle growth is limited upon oxidative treatment. A hydrogen treatment in aqueous phase at 363 K causes platinum particle growth, aggregate formation, and covering of metal sites. These phenomena become more important with increasing pH. Platinum particle growth and aggregate formation are attributed to platinum particle rather than platinum adatom mobility and is caused by the destruction of the oxygen-containing surface groups on the graphite support, which serve as anchorage sites for the platinum particles. Site covering is caused by products originating from the graphite support, which are formed as a result of the reductive treatments. When performing the aqueous phase oxidation of methyl {alpha}-D-glucopyranoside at 323 K and a pH of 9, catalyst modifications are small under oxidative conditions. Exposure of the catalyst for several hours to methyl {alpha}-D-glucopyranoside under the same conditions but in the absence of oxygen causes site covering. 50 refs., 9 figs., 1 tab.

  15. Discerning the Location and Nature of Coke Deposition from Surface to Bulk of Spent Zeolite Catalysts

    Science.gov (United States)

    Devaraj, Arun; Vijayakumar, Murugesan; Bao, Jie; Guo, Mond F.; Derewinski, Miroslaw A.; Xu, Zhijie; Gray, Michel J.; Prodinger, Sebastian; Ramasamy, Karthikeyan K.

    2016-11-01

    The formation of carbonaceous deposits (coke) in zeolite pores during catalysis leads to temporary deactivation of catalyst, necessitating regeneration steps, affecting throughput, and resulting in partial permanent loss of catalytic efficiency. Yet, even to date, the coke molecule distribution is quite challenging to study with high spatial resolution from surface to bulk of the catalyst particles at a single particle level. To address this challenge we investigated the coke molecules in HZSM-5 catalyst after ethanol conversion treatment by a combination of C K-edge X-ray absorption spectroscopy (XAS), 13C Cross polarization-magic angle spinning nuclear magnetic resonance (CP-MAS NMR) spectroscopy, and atom probe tomography (APT). XAS and NMR highlighted the aromatic character of coke molecules. APT permitted the imaging of the spatial distribution of hydrocarbon molecules located within the pores of spent HZSM-5 catalyst from surface to bulk at a single particle level. 27Al NMR results and APT results indicated association of coke molecules with Al enriched regions within the spent HZSM-5 catalyst particles. The experimental results were additionally validated by a level-set-based APT field evaporation model. These results provide a new approach to investigate catalytic deactivation due to hydrocarbon coking or poisoning of zeolites at an unprecedented spatial resolution.

  16. Leaching of vanadium from sulphuric acid manufacture spent catalysts

    International Nuclear Information System (INIS)

    Garcia, D. J.; Lozano Blanco, L. J.; Mulero Vivancos, M. D.

    2001-01-01

    Recovery of vanadium contained in spent catalyst from the manufacture of sulphuric acid has been studied in this work, resulting in an industrial multistage process for the treatment of them avoiding direct deposition or dumping. Characterization of supplied spent catalysts samples, confirmed vanadium levels showed in the literature. The study of variables influencing leaching process: type of leaching agent, leaching agent concentration, S/L ratio, stirring speed and temperature, allows to fix the most advantageous conditions using industrial application criterion and verifying that the process is diffusion controlled. the work is completed by developing an industrial leaching cycle simulation with the aim of reproducing real performance of spent, proposing operating conditions, and verifying the non-toxic character of the final residue obtained. (Author) 18 refs

  17. The 'Invisible' Metal Particles in Catalysis

    NARCIS (Netherlands)

    Koningsberger, D.C.; Diaz-Moreno, S.; Muñoz-Paez, A.

    1997-01-01

    An easy, reliable and straightforward method to determine the sizes of small metal particles in supported metal catalyst which are invisible for most techniques (chemisorption, XRD, HRTEM) is presented. The technique we consider more appropriate is EXAFS, because it detects metal metal bonds even

  18. Residual gas analysis

    International Nuclear Information System (INIS)

    Berecz, I.

    1982-01-01

    Determination of the residual gas composition in vacuum systems by a special mass spectrometric method was presented. The quadrupole mass spectrometer (QMS) and its application in thin film technology was discussed. Results, partial pressure versus time curves as well as the line spectra of the residual gases in case of the vaporization of a Ti-Pd-Au alloy were demonstrated together with the possible construction schemes of QMS residual gas analysers. (Sz.J.)

  19. The innovation catalysts.

    Science.gov (United States)

    Martin, Roger L

    2011-06-01

    A few years ago the software development company Intuit realized that it needed a new approach to galvanizing customers. The company's Net Promoter Score was faltering, and customer recommendations of new products were especially disappointing. Intuit decided to hold a two-day, off-site meeting for the company's top 300 managers with a focus on the role of design in innovation. One of the days was dedicated to a program called Design for Delight. The centerpiece of the day was a PowerPoint presentation by Intuit founder Scott Cook, who realized midway through that he was no Steve Jobs: The managers listened dutifully, but there was little energy in the room. By contrast, a subsequent exercise in which the participants worked through a design challenge by creating prototypes, getting feedback, iterating, and refining, had them mesmerized. The eventual result was the creation of a team of nine design-thinking coaches--"innovation catalysts"--from across Intuit who were made available to help any work group create prototypes, run experiments, and learn from customers. The process includes a "painstorm" (to determine the customer's greatest pain point), a "soljam" (to generate and then winnow possible solutions), and a "code-jam" (to write code "good enough" to take to customers within two weeks). Design for Delight has enabled employees throughout Intuit to move from satisfying customers to delighting them.

  20. Magnetism for understanding catalyst analysis of purified carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Bellouard, Christine; Mercier, Guillaume; Cahen, Sébastien; Ghanbaja, Jaafar; Medjahdi, Ghouti [Institut Jean Lamour, CNRS-Université de Lorraine, BP 70239, 54506 Vandoeuvre-lès-Nancy (France); Gleize, Jérôme [Laboratoire de Chimie Physique-Approche Multi-échelle de Milieux Complexes-Université de Lorraine, 1 Bd Arago, 57078 Metz (France); Lamura, Gianrico [CNR-SPIN – Dipartimento di Fisica, via Dodecaneso 33, 16146 Genova (Italy); Hérold, Claire [Institut Jean Lamour, CNRS-Université de Lorraine, BP 70239, 54506 Vandoeuvre-lès-Nancy (France); Vigolo, Brigitte, E-mail: Brigitte.Vigolo@univ-lorraine.fr [Institut Jean Lamour, CNRS-Université de Lorraine, BP 70239, 54506 Vandoeuvre-lès-Nancy (France)

    2016-08-01

    The precise quantification of catalyst residues in purified carbon nanotubes is often a major issue in view of any fundamental and/or applicative studies. More importantly, since the best CNTs are successfully grown with magnetic catalysts, their quantification becomes strictly necessary to better understand intrinsic properties of CNT. For these reasons, we have deeply analyzed the catalyst content remained in nickel–yttrium arc-discharge single walled carbon nanotubes purified by both a chlorine-gas phase and a standard acid-based treatment. The study focuses on Ni analysis which has been investigated by transmission electron microscopy, X-ray diffraction, thermogravimetry analysis, and magnetic measurements. In the case of the acid-based treatment, all quantifications result in a decrease of the nanocrystallized Ni by a factor of two. In the case of the halogen gas treatment, analysis and quantification of Ni content is less straightforward: a huge difference appears between X-ray diffraction and thermogravimetry results. Thanks to magnetic measurements, this disagreement is explained by the presence of Ni{sup 2+} ions, belonging to NiCl{sub 2} formed during the Cl-based purification process. In particular, NiCl{sub 2} compound appears under different magnetic/crystalline phases: paramagnetic or diamagnetic, or well intercalated in between carbon sheets with an ordered magnetic phase at low temperature. - Highlights: • Cl-gas treatment of Ni catalyst of carbon nanotubes leads to NiCl{sub 2} residue. • Magnetic measurements show the transformation of Ni{sup 0} in Ni{sup 2+}through a purification process. • High temperature Cl treatment removes 75% of metallic impurities. • Cl-purification yields to an amount of metal of 1.5% in arc-discharge CNT samples.

  1. Rare Earth Element Phases in Bauxite Residue

    Directory of Open Access Journals (Sweden)

    Johannes Vind

    2018-02-01

    Full Text Available The purpose of present work was to provide mineralogical insight into the rare earth element (REE phases in bauxite residue to improve REE recovering technologies. Experimental work was performed by electron probe microanalysis with energy dispersive as well as wavelength dispersive spectroscopy and transmission electron microscopy. REEs are found as discrete mineral particles in bauxite residue. Their sizes range from <1 μm to about 40 μm. In bauxite residue, the most abundant REE bearing phases are light REE (LREE ferrotitanates that form a solid solution between the phases with major compositions (REE,Ca,Na(Ti,FeO3 and (Ca,Na(Ti,FeO3. These are secondary phases formed during the Bayer process by an in-situ transformation of the precursor bauxite LREE phases. Compared to natural systems, the indicated solid solution resembles loparite-perovskite series. LREE particles often have a calcium ferrotitanate shell surrounding them that probably hinders their solubility. Minor amount of LREE carbonate and phosphate minerals as well as manganese-associated LREE phases are also present in bauxite residue. Heavy REEs occur in the same form as in bauxites, namely as yttrium phosphates. These results show that the Bayer process has an impact on the initial REE mineralogy contained in bauxite. Bauxite residue as well as selected bauxites are potentially good sources of REEs.

  2. Nanostructured catalysts for organic transformations.

    Science.gov (United States)

    Chng, Leng Leng; Erathodiyil, Nandanan; Ying, Jackie Y

    2013-08-20

    The development of green, sustainable and economical chemical processes is one of the major challenges in chemistry. Besides the traditional need for efficient and selective catalytic reactions that will transform raw materials into valuable chemicals, pharmaceuticals and fuels, green chemistry also strives for waste reduction, atomic efficiency and high rates of catalyst recovery. Nanostructured materials are attractive candidates as heterogeneous catalysts for various organic transformations, especially because they meet the goals of green chemistry. Researchers have made significant advances in the synthesis of well-defined nanostructured materials in recent years. Among these are novel approaches that have permitted the rational design and synthesis of highly active and selective nanostructured catalysts by controlling the structure and composition of the active nanoparticles (NPs) and by manipulating the interaction between the catalytically active NP species and their support. The ease of isolation and separation of the heterogeneous catalysts from the desired organic product and the recovery and reuse of these NPs further enhance their attractiveness as green and sustainable catalysts. This Account reviews recent advances in the use of nanostructured materials for catalytic organic transformations. We present a broad overview of nanostructured catalysts used in different types of organic transformations including chemoselective oxidations and reductions, asymmetric hydrogenations, coupling reactions, C-H activations, oxidative aminations, domino and tandem reactions, and more. We focus on recent research efforts towards the development of the following nanostructured materials: (i) nanostructured catalysts with controlled morphologies, (ii) magnetic nanocomposites, (iii) semiconductor-metal nanocomposites, and (iv) hybrid nanostructured catalysts. Selected examples showcase principles of nanoparticle design such as the enhancement of reactivity, selectivity

  3. Interfaces in Heterogeneous Catalysts: Advancing Mechanistic Understanding through Atomic-Scale Measurements.

    Science.gov (United States)

    Gao, Wenpei; Hood, Zachary D; Chi, Miaofang

    2017-04-18

    Developing novel catalysts with high efficiency and selectivity is critical for enabling future clean energy conversion technologies. Interfaces in catalyst systems have long been considered the most critical factor in controlling catalytic reaction mechanisms. Interfaces include not only the catalyst surface but also interfaces within catalyst particles and those formed by constructing heterogeneous catalysts. The atomic and electronic structures of catalytic surfaces govern the kinetics of binding and release of reactant molecules from surface atoms. Interfaces within catalysts are introduced to enhance the intrinsic activity and stability of the catalyst by tuning the surface atomic and chemical structures. Examples include interfaces between the core and shell, twin or domain boundaries, or phase boundaries within single catalyst particles. In supported catalyst nanoparticles (NPs), the interface between the metallic NP and support serves as a critical tuning factor for enhancing catalytic activity. Surface electronic structure can be indirectly tuned and catalytically active sites can be increased through the use of supporting oxides. Tuning interfaces in catalyst systems has been identified as an important strategy in the design of novel catalysts. However, the governing principle of how interfaces contribute to catalyst behavior, especially in terms of interactions with intermediates and their stability during electrochemical operation, are largely unknown. This is mainly due to the evolving nature of such interfaces. Small changes in the structural and chemical configuration of these interfaces may result in altering the catalytic performance. These interfacial arrangements evolve continuously during synthesis, processing, use, and even static operation. A technique that can probe the local atomic and electronic interfacial structures with high precision while monitoring the dynamic interfacial behavior in situ is essential for elucidating the role of

  4. Chemoselective Oxidation of Bio-Glycerol with Nano-Sized Metal Catalysts

    DEFF Research Database (Denmark)

    Li, Hu; Kotni, Ramakrishna; Zhang, Qiuyun

    2015-01-01

    to selectively oxidize glycerol and yield products with good selectivity is the use of nano-sized metal particles as heterogeneous catalysts. In this short review, recent developments in chemoselective oxidation of glycerol to specific products over nano-sized metal catalysts are described. Attention is drawn...... to various reaction parameters such as the type of the support, the size of the metal particles, and the acid/base properties of the reaction medium which were illustrated to largely influence the activity of the nanocatalyst and selectivity to the target product. - See more at: http...

  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. Reduction and reoxidation of cobalt Fischer-Tropsch catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Hilmen, Anne-Mette

    1996-12-31

    The Fischer-Tropsch synthesis involves the hydrogenation of carbon monoxide to produce mainly hydrocarbons, water and carbon dioxide, but also alcohols, aldehydes and acids are formed. The distribution of these products is determined by the choice of catalyst and synthesis conditions. This thesis studies the reduction and reoxidation of 17%Co/Al{sub 2}O{sub 3} and 17%Co-1%Re/Al{sub 2}O{sub 3} by means of several characterization techniques. The effect of small amounts of Re on the reduction properties of Al{sub 2}O{sub 3}-supported Co catalysts has been studied by temperature-programmed reduction (TPR). An intimate mixture of CoAl{sub 2}O{sub 3} and Re/Al{sub 2}O{sub 3} catalysts showed a promoting effect of Re similar to that for co impregnated CoRe/Al{sub 2}O{sub 3}. A loose mixture of Co/Al{sub 2}O{sub 3} + Re/Al{sub 2}O{sub 3} did not show any effect of Re on the reduction of Co. But a promoting effect was observed if the mixture had been pre-treated with Ar saturated with water before the TPR. It is suggested that Re promotes the reduction of Co oxide by hydrogen spillover. It is shown that a high temperature TPK peak at 1200K assigned to Co aluminate is mainly caused by the diffusion of Co ions during the TPR and not during calcination. The Co particle size measured by x-ray diffraction on oxidized catalysts decreased compared to the particle size on the calcined catalysts, while the dispersion measured by volumetric chemisorption decreased somewhat after the oxidation-reduction treatment. The role of water in the deactivation of Co/Al{sub 2}O{sub 3} and CoRe/Al{sub 2}O{sub 3} Fischer-Tropsch catalysts has been extensively studied. There were significant differences in the reducibility of the phases formed for the two catalysts during exposure to H{sub 2}O/He. 113 refs., 76 figs., 18 tabs.

  7. Adhesion of solid particles to gas bubbles. Part 2: Experimental

    NARCIS (Netherlands)

    Omota, Florin; Dimian, Alexandre C.; Bliek, A.

    2006-01-01

    In slurry bubble columns, the adhesion of solid catalyst particles to bubbles may significantly affect the G–L mass transfer and bubble size distribution. This feature may be exploited in design by modifying the hydrophilic or hydrophobic nature of the particles used. Previously we have proposed a

  8. Life and death of a single catalytic cracking particle

    NARCIS (Netherlands)

    Meirer, Florian; Kalirai, Samanbir; Morris, Darius; Soparawalla, Santosh; Liu, Yijin; Mesu, Gerbrand; Andrews, Joy C; Weckhuysen, Bert M

    Fluid catalytic cracking (FCC) particles account for 40 to 45% of worldwide gasoline production. The hierarchical complex particle pore structure allows access of long-chain feedstock molecules into active catalyst domains where they are cracked into smaller, more valuable hydrocarbon products (for

  9. Wire gauze and cordierite supported noble metal catalysts for passive autocatalytic recombiner

    International Nuclear Information System (INIS)

    Sanap, Kiran K.; Varma, S.; Waghmode, S.B.; Bharadwaj, S.R.

    2015-01-01

    Highlights: • Synthesis by electroless deposition method and chemical reduction route. • Particle size of 0.1–0.5 μm & 3.5–5 nm for Pt–Pd/Wg & Pt–Pd/Cord catalysts. • Active for H 2 and O 2 reaction with initial H 2 concentration of 1.5 to 7% in air. • Active in presence of different contaminants like CO 2 , CH 4 , CO & relative humidity. • Enhanced resistance of Pt–Pd/Cord catalyst towards the poisoning of CO. - Abstract: Hydrogen released in nuclear reactor containment under severe accident scenario poses a threat to containment and hence needs to be regulated by catalytic recombination. Mixed noble metal catalysts with platinum–palladium supported on stainless steel wire gauze and cordierite support have been developed for this purpose. The developed catalysts have been found to be highly efficient for removal of hydrogen concentration in the range of 1.5 to 7.0% v/v in air. Though both the catalysts exhibit similar kinetics for lower hydrogen concentration, cordierite supported catalysts exhibits better kinetic rate at higher hydrogen concentration. The performances of these catalysts in presence of various probable catalytic poison like carbon monoxide and catalytic inhibitors like moisture, carbon dioxide, and hydrocarbons provide data for use of these catalysts under the actual scenario. Compared to stainless steel wire gauze supported catalyst, the cordierite based catalyst are found to exhibit enhanced resistance towards carbon monoxide and limited temperature rise for safer application at higher hydrogen concentrations.

  10. Interfacial charge distributions in carbon-supported palladium catalysts.

    Science.gov (United States)

    Rao, Radhika G; Blume, Raoul; Hansen, Thomas W; Fuentes, Erika; Dreyer, Kathleen; Moldovan, Simona; Ersen, Ovidiu; Hibbitts, David D; Chabal, Yves J; Schlögl, Robert; Tessonnier, Jean-Philippe

    2017-08-24

    Controlling the charge transfer between a semiconducting catalyst carrier and the supported transition metal active phase represents an elite strategy for fine turning the electronic structure of the catalytic centers, hence their activity and selectivity. These phenomena have been theoretically and experimentally elucidated for oxide supports but remain poorly understood for carbons due to their complex nanoscale structure. Here, we combine advanced spectroscopy and microscopy on model Pd/C samples to decouple the electronic and surface chemistry effects on catalytic performance. Our investigations reveal trends between the charge distribution at the palladium-carbon interface and the metal's selectivity for hydrogenation of multifunctional chemicals. These electronic effects are strong enough to affect the performance of large (~5 nm) Pd particles. Our results also demonstrate how simple thermal treatments can be used to tune the interfacial charge distribution, hereby providing a strategy to rationally design carbon-supported catalysts.Control over charge transfer in carbon-supported metal nanoparticles is essential for designing new catalysts. Here, the authors show that thermal treatments effectively tune the interfacial charge distribution in carbon-supported palladium catalysts with consequential changes in hydrogenation performance.

  11. Bimetallic Nanoparticles as Efficient Catalysts: Facile and Green Microwave Synthesis

    Science.gov (United States)

    Blosi, Magda; Ortelli, Simona; Costa, Anna Luisa; Dondi, Michele; Lolli, Alice; Andreoli, Sara; Benito, Patricia; Albonetti, Stefania

    2016-01-01

    This work deals with the development of a green and versatile synthesis of stable mono- and bi-metallic colloids by means of microwave heating and exploiting ecofriendly reagents: water as the solvent, glucose as a mild and non-toxic reducer and polyvinylpirrolidone (PVP) as the chelating agent. Particle size-control, total reaction yield and long-term stability of colloids were achieved with this method of preparation. All of the materials were tested as effective catalysts in the reduction of p-nitrophenol in the presence of NaBH4 as the probe reaction. A synergistic positive effect of the bimetallic phase was assessed for Au/Cu and Pd/Au alloy nanoparticles, the latter showing the highest catalytic performance. Moreover, monoand bi-metallic colloids were used to prepare TiO2- and CeO2-supported catalysts for the liquid phase oxidation of 5-hydroxymethylfufural (HMF) to 2,5-furandicarboxylic acid (FDCA). The use of Au/Cu and Au/Pd bimetallic catalysts led to an increase in FDCA selectivity. Finally, preformed Pd/Cu nanoparticles were incorporated into the structure of MCM-41-silica. The resulting Pd/Cu MCM-41 catalysts were tested in the hydrodechlorination of CF3OCFClCF2Cl to CF3OCF=CF2. The effect of Cu on the hydrogenating properties of Pd was demonstrated. PMID:28773672

  12. Bimetallic Nanoparticles as Efficient Catalysts: Facile and Green Microwave Synthesis

    Directory of Open Access Journals (Sweden)

    Magda Blosi

    2016-07-01

    Full Text Available This work deals with the development of a green and versatile synthesis of stable mono- and bi-metallic colloids by means of microwave heating and exploiting ecofriendly reagents: water as the solvent, glucose as a mild and non-toxic reducer and polyvinylpirrolidone (PVP as the chelating agent. Particle size-control, total reaction yield and long-term stability of colloids were achieved with this method of preparation. All of the materials were tested as effective catalysts in the reduction of p-nitrophenol in the presence of NaBH4 as the probe reaction. A synergistic positive effect of the bimetallic phase was assessed for Au/Cu and Pd/Au alloy nanoparticles, the latter showing the highest catalytic performance. Moreover, monoand bi-metallic colloids were used to prepare TiO2- and CeO2-supported catalysts for the liquid phase oxidation of 5-hydroxymethylfufural (HMF to 2,5-furandicarboxylic acid (FDCA. The use of Au/Cu and Au/Pd bimetallic catalysts led to an increase in FDCA selectivity. Finally, preformed Pd/Cu nanoparticles were incorporated into the structure of MCM-41-silica. The resulting Pd/Cu MCM-41 catalysts were tested in the hydrodechlorination of CF3OCFClCF2Cl to CF3OCF=CF2. The effect of Cu on the hydrogenating properties of Pd was demonstrated.

  13. Hierarchical hybrid peroxidase catalysts for remediation of phenol wastewater

    KAUST Repository

    Duan, Xiaonan

    2014-02-20

    We report a new family of hierarchical hybrid catalysts comprised of horseradish peroxidase (HRP)-magnetic nanoparticles for advanced oxidation processes and demonstrate their utility in the removal of phenol from water. The immobilized HRP catalyzes the oxidation of phenols in the presence of H2O2, producing free radicals. The phenoxy radicals react with each other in a non-enzymatic process to form polymers, which can be removed by precipitation with salts or condensation. The hybrid peroxidase catalysts exhibit three times higher activity than free HRP and are able to remove three times more phenol from water compared to free HRP under similar conditions. In addition, the hybrid catalysts reduce substrate inhibition and limit inactivation from reaction products, which are common problems with free or conventionally immobilized enzymes. Reusability is improved when the HRP-magnetic nanoparticle hybrids are supported on micron-scale magnetic particles, and can be retained with a specially designed magnetically driven reactor. The performance of the hybrid catalysts makes them attractive for several industrial and environmental applications and their development might pave the way for practical applications by eliminating most of the limitations that have prevented the use of free or conventionally immobilized enzymes. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Hierarchical hybrid peroxidase catalysts for remediation of phenol wastewater.

    Science.gov (United States)

    Duan, Xiaonan; Corgié, Stéphane C; Aneshansley, Daniel J; Wang, Peng; Walker, Larry P; Giannelis, Emmanuel P

    2014-04-04

    We report a new family of hierarchical hybrid catalysts comprised of horseradish peroxidase (HRP)-magnetic nanoparticles for advanced oxidation processes and demonstrate their utility in the removal of phenol from water. The immobilized HRP catalyzes the oxidation of phenols in the presence of H2 O2 , producing free radicals. The phenoxy radicals react with each other in a non-enzymatic process to form polymers, which can be removed by precipitation with salts or condensation. The hybrid peroxidase catalysts exhibit three times higher activity than free HRP and are able to remove three times more phenol from water compared to free HRP under similar conditions. In addition, the hybrid catalysts reduce substrate inhibition and limit inactivation from reaction products, which are common problems with free or conventionally immobilized enzymes. Reusability is improved when the HRP-magnetic nanoparticle hybrids are supported on micron-scale magnetic particles, and can be retained with a specially designed magnetically driven reactor. The performance of the hybrid catalysts makes them attractive for several industrial and environmental applications and their development might pave the way for practical applications by eliminating most of the limitations that have prevented the use of free or conventionally immobilized enzymes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. High-performance bimetallic alloy catalyst using Ni and N co-doped composite carbon for the oxygen electro-reduction.

    Science.gov (United States)

    Jung, Won Suk

    2018-03-15

    In this study, a novel synthesis method for the bimetallic alloy catalyst is reported, which is subsequently used as an oxygen reduction catalyst in polymer electrolyte membrane fuel cells (PEMFCs). The support prepared from the Ni-chelate complex shows a mesoporous structure with a specific surface area of ca. 400 m 2  g -1 indicating the suitable support for PEMFC applications. Ethylenediamine is converted to the nitrogen and carbon layers to protect the Ni particles which will diffuse into the Pt lattice at 800 °C. The PtNi/NCC catalyst with PtNi cores and Pt-rich shells is successfully formed when acid-treated as evidenced by line scan profiles. The catalyst particles thus synthesized are well-dispersed on the N-doped carbon support, while the average particle size is ca. 3 nm. In the PEMFC test, the maximum power density of the PtNi/NCC catalyst shows approximately 25% higher than that of the commercial Pt/C catalyst. The mass activity of the PtNi/NCC catalyst showed approximately 3-fold higher than that of the commercial Pt/C catalyst. The mass activity strongly depends on the ratio of Pt to Ni since the strain effect can be strong for catalysts due to the mismatch of lattice parameters of the Ni and Pt. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. From Colloidal Monodisperse Nickel Nanoparticles to Well-Defined Ni/Al2O3Model Catalysts.

    Science.gov (United States)

    Zacharaki, Eirini; Beato, Pablo; Tiruvalam, Ramchandra R; Andersson, Klas J; Fjellvåg, Helmer; Sjåstad, Anja O

    2017-09-26

    In the past few decades, advances in colloidal nanoparticle synthesis have created new possibilities for the preparation of supported model catalysts. However, effective removal of surfactants is a prerequisite to evaluate the catalytic properties of these catalysts in any reaction of interest. Here we report on the colloidal preparation of surfactant-free Ni/Al 2 O 3 model catalysts. Monodisperse Ni nanoparticles (NPs) with mean particle size ranging from 4 to 9 nm were synthesized via thermal decomposition of a zerovalent precursor in the presence of oleic acid. Five weight percent Ni/Al 2 O 3 catalysts were produced by direct deposition of the presynthesized NPs on an alumina support, followed by thermal activation (oxidation-reduction cycle) for complete surfactant removal and surface cleaning. Structural and morphological characteristics of the nanoscale catalysts are described in detail following the propagation of the bulk and surface Ni species at the different treatment stages. Powder X-ray diffraction, electron microscopy, and temperature-programmed reduction experiments as well as infrared spectroscopy of CO adsorption and magnetic measurements were conducted. The applied thermal treatments are proven to be fully adequate for complete surfactant removal while preserving the metal particle size and the size distribution at the level attained by the colloidal synthesis. Compared with standard impregnated Ni/Al 2 O 3 catalysts, the current model materials display narrowed Ni particle size distributions and increased reducibility with a higher fraction of the metallic nickel atoms exposed at the catalyst surface.

  17. New Method to Synthesize Highly Active and Durable Chemically Ordered fct-PtCo Cathode Catalyst for PEMFCs.

    Science.gov (United States)

    Jung, Won Suk; Popov, Branko N

    2017-07-19

    In the bottom-up synthesis strategy performed in this study, the Co-catalyzed pyrolysis of chelate-complex and activated carbon black at high temperatures triggers the graphitization reaction which introduces Co particles in the N-doped graphitic carbon matrix and immobilizes N-modified active sites for the oxygen reduction reaction (ORR) on the carbon surface. In this study, the Co particles encapsulated within the N-doped graphitic carbon shell diffuse up to the Pt surface under the polymer protective layer and forms a chemically ordered face-centered tetragonal (fct) Pt-Co catalyst PtCo/CCCS catalyst as evidenced by structural and compositional studies. The fct-structured PtCo/CCCS at low-Pt loading (0.1 mg Pt cm -2 ) shows 6% higher power density than that of the state-of-the-art commercial Pt/C catalyst. After the MEA durability test of 30 000 potential cycles, the performance loss of the catalyst is negligible. The electrochemical surface area loss is less than 40%, while that of commercial Pt/C is nearly 80%. After the accelerated stress test, the uniform catalyst distribution is retained and the mean particle size increases approximate 1 nm. The results obtained in this study indicated that highly stable compositional and structural properties of chemically ordered PtCo/CCCS catalyst contribute to its exceptional catalyst durability.

  18. Agricultural pesticide residues

    International Nuclear Information System (INIS)

    Fuehr, F.

    1984-01-01

    The utilization of tracer techniques in the study of agricultural pesticide residues is reviewed under the following headings: lysimeter experiments, micro-ecosystems, translocation in soil, degradation of pesticides in soil, biological availability of soil-applied substances, bound residues in the soil, use of macro- and microautography, double and triple labelling, use of tracer labelling in animal experiments. (U.K.)

  19. Sintering and Particle Dynamics in Supported Metal Catalysts

    DEFF Research Database (Denmark)

    Hansen, Thomas Willum

    2006-01-01

    temperatur og højt damptryk har Ni partiklerne en tendens til gro sammen, hvormed katalysatorens ydeevne falder. Dette vækstfænomen kaldes sintring. For at opnå en større forståelse af de involverede mekanismer er der i ph.d. studiet arbejdet med in situ transmissionselektronmikroskopi (in situ TEM), der er...

  20. Evaluation of gunshot residue (GSR) evidence: Surveys of prevalence of GSR on clothing and frequency of residue types.

    Science.gov (United States)

    Hannigan, Thomas J; McDermott, Sean D; Greaney, Claire M; O'Shaughnessy, John; O'Brien, Cliona M

    2015-12-01

    The evaluative approach is a logical approach to interpreting scientific findings in criminal cases, applying knowledge regarding the transfer, persistence and recovery of particulate material. The application of this approach to interpreting the finding of gunshot residue on the clothing of a suspect requires knowledge of background levels of GSR on clothing and on the frequency of different residue types in a particular environment. The cuffs of 100 upper outer garments submitted to a forensic laboratory in connection with non-firearms offences were sampled for gunshot residue. No 3-component lead/antimony/barium particles were found on 98 of them. Two 3-component particles were found on one of them and one 3-component particle was found on another. The frequency of occurrence of various particle types regarded as consistent with GSR was also explored. The findings show that, while 3-component particles were somewhat more likely to be encountered by chance on clothing than on hands, they are still relatively uncommon events. To investigate the frequency of occurrence of particular residue types, 100 discharged rounds of ammunition recovered at crime scenes were sampled and the types of residue present were determined. The results show that some residue types are significantly more common than others. Both sets of data will be of value in evaluating the significance of finding GSR on clothing of suspects in criminal cases. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  1. Synthesis, characterization and analysis of platinum-based multiphase catalysts for direct ethanol fuel cells

    Science.gov (United States)

    Mann, Jonathan R.

    Platinum-based particles are synthesized via the polyol process in an effort to include various metal oxides in a multi-phase catalyst for the direct ethanol fuel cell anode. Among Eu, In, La and Nb, no single metal oxide with platinum yields open circuit potentials or maximum current densities as high as tin oxide with platinum. For this reason, particles with platinum, tin oxide and the oxide of a third metal were developed. Platinum tin/indium oxide slightly outperforms platinum tin oxide. The particles are characterized by TEM, EDX, XRD and ICP. The metal oxides and the platinum are located together in one particle, uniformly 5.3 nm in diameter. ICP analysis indicates that the catalysts are 20% platinum on carbon and the metals of the oxides are on the order of 1-2% by mass. The catalytic abilities of the particles were evaluated in a single cell direct ethanol fuel cell where polarization curves were taken up to 130°C, and oxidation products were analyzed by gas chromatography. Open circuit voltages of as high as 0.82 V were obtained for platinum tin/indium oxide catalysts and current densities as high as 0.4 A cm-2 were seen. The cells produced large amounts of acetaldehyde and acetic acid, as well as small amounts of methanol and carbon dioxide. A spillover mechanism is proposed for the oxidation of ethanol to CO2 on these platinum/metal oxide catalysts.

  2. Thermal and catalytic ASVAHL processes under hydrogen pressure for converting heavy crudes and conventional residues

    Energy Technology Data Exchange (ETDEWEB)

    Peries, J.P.; Quignard, A.; Farjon, C.; Laborde, M.

    This article describes the comparative performances of thermal ASVAHL processes (TERVAHL T, TERVAHL H, TERVAHL HC) and catalytic ASVAHL processes (HYVAHL F, HYVAHL C) for two types of processing: (1) degasolined Boscan crude (basis of studies for transportation feasibility), and (2) Safaniya vacuum residue (basis of studies for residue refining). The results reveal the importance of the amount of fixed hydrogen, which affects the conversion obtained and the quality of the residues. The introduction of a TERVAHL HC soluble catalyst or one in catalytic suspension (catalytic hydrovisbreaking) or the use of a supported catalyst (HYVAHL hydrotreatment) enhances the activation of hydrogen. The combination of cracking, polycondensation and hydrogen reactions together with the operating conditions (temperatures, residence time and pressure) are what will define the conversion limits for a given stability of residues.

  3. CO Sensing Performance of a Micro Thermoelectric Gas Sensor with AuPtPd/SnO2 Catalyst and Effects of a Double Catalyst Structure with Pt/?-Al2O3

    OpenAIRE

    Goto, Tomoyo; Itoh, Toshio; Akamatsu, Takafumi; Shin, Woosuck

    2015-01-01

    The CO sensing properties of a micro thermoelectric gas sensor (micro-TGS) with a double AuPtPd/SnO2 and Pt/α-Al2O3 catalyst were investigated. While several nanometer sized Pt and Pd particles were uniformly dispersed on SnO2, the Au particles were aggregated as particles measuring >10 nm in diameter. In situ diffuse reflectance Fourier transform Infrared spectroscopy (DRIFT) analysis of the catalyst showed a CO adsorption peak on Pt and Pd, but no clear peak corresponding to the interact...

  4. Regeneration of Hydrotreating and FCC Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    CM Wai; JG Frye; JL Fulton; LE Bowman; LJ Silva; MA Gerber

    1999-09-30

    Hydrotreating, hydrocracking, and fluid catalytic cracking (FCC) catalysts are important components of petroleum refining processes. Hydrotreating and hydrocracking catalysts are used to improve the yield of high-quality light oil fractions from heavier crude oil and petroleum feedstocks containing high levels of impurities. FCC catalysts improve the yield of higher octane gasoline from crude oil. Residuum hydrotreating and cracking catalysts are susceptible to irreversible deactivation caused by adsorption of sulfur and by metals impurities, such as vanadium and nickel. The gradual buildup of these impurities in a hydrotreating catalyst eventually plugs the pores and deactivates it. Nickel and vanadium adversely affect the behavior of cracking catalysts, reducing product yield and quality. Replacing deactivated catalysts represents a significant cost in petroleum refining. Equally important are the costs and potential liabilities associated with treating and disposing spent catalysts. For example, recent US Environmental Protection Agency rulings have listed spent hydrotreating and hydrorefining catalysts as hazardous wastes. FCC catalysts, though more easily disposed of as road-base or as filler in asphalt and cement, are still an economic concern mainly because of the large volumes of spent catalysts generated. New processes are being considered to increase the useful life of catalysts or for meeting more stringent disposal requirements for spent catalysts containing metals. This report discusses a collaborative effort between Pacific Northwest National Laboratory (PNNL) and Phillips Petroleum, Inc., to identify promising chemical processes for removing metals adhered to spent hydrodesulfurization (HDS, a type of hydrotreating catalyst) and FCC catalysts. This study, conducted by PNNL, was funded by the US Department of Energy's Bartlesville Project Office. Fresh and spent catalysts were provided by Phillips Petroleum. The FCC catalyst was a rare

  5. Preparation of catalyst coated membrane by modified decal transfer method for proton exchange membrane fuel cell

    Science.gov (United States)

    Indriyati; Irmawati, Y.; Prihandoko, B.

    2017-07-01

    A new catalyst coated membrane (CCM) was prepared by modified decal transfer method. A structure of ionomer/catalyst/carbon/substrate was used to facilitate the transfer of catalyst layer from decal substrate to the membrane at quite low hot-pressing temperature (120 °C) for 8 min. Several decal substrates were tested to select a proper substrate, namely PTFE cloth, PTFE film, aluminium foil, and OHP transparent sheet. The transfer degree of catalyst layer was estimated. Elemental analysis and SEM-mapping were performed to evaluate the residue, whereas contact angle measurement was conducted to characterize the hydrophobicity of decal substrates. The results showed that PTFE cloth and PFTE film transferred approximately 90% of catalyst layer onto the membrane, while the other two substrates were around 70%. Furthermore, the elemental analysis of the residue on the substrate revealed that it was mainly composed of carbon and fluorine for PTFE cloth and PTFE film. This result supports other findings that PTFE cloth and PTFE film are suitable as decal substrate at low temperature hot pressing for fabricating CCM.

  6. Cosmic particles

    International Nuclear Information System (INIS)

    Fritszh, Harald; Max-Planck-Institut fuer Physik und Astrophysik, Muenchen

    1986-01-01

    The paper on 'Cosmic particles' was presented at the conference on 'The early universe and its evolution', Erice, Italy 1986. The link between ideas in cosmology and in elementary particle physics is examined. The subject is discussed under the following topic headings: cosmic kinetics, cosmic dynamics and general relativity, dynamics of the dust universe, particle physics, unity of quarks and leptons, the hot universe and standard particle physics, creation of matter, and the inflation of the universe. (U.K.)

  7. High activity PtRu/C catalysts synthesized by a modified impregnation method for methanol electro-oxidation

    International Nuclear Information System (INIS)

    Ma Liang; Liu Changpeng; Liao Jianhui; Lu Tianhong; Xing Wei; Zhang Jiujun

    2009-01-01

    A modified impregnation method was used to prepare highly dispersive carbon-supported PtRu catalyst (PtRu/C). Two modifications to the conventional impregnation method were performed: one was to precipitate the precursors ((NH 4 ) 2 PtCl 6 and Ru(OH) 3 ) on the carbon support before metal reduction; the other was to add a buffer into the synthetic solution to stabilize the pH. The prepared catalyst showed a much higher activity for methanol electro-oxidation than a catalyst prepared by the conventional impregnation method, even higher than that of current commercially available, state-of-the-art catalysts. The morphology of the prepared catalyst was characterized using TEM and XRD measurements to determine particle sizes, alloying degree, and lattice parameters. Electrochemical methods were also used to ascertain the electrochemical active surface area and the specific activity of the catalyst. Based on XPS measurements, the high activity of this catalyst was found to originate from both metallic Ru (Ru 0 ) and hydrous ruthenium oxides (RuO x H y ) species on the catalyst surface. However, RuO x H y was found to be more active than metallic Ru. In addition, the anhydrous ruthenium oxide (RuO 2 ) species on the catalyst surface was found to be less active.

  8. Hydrodechlorination of Tetrachloromethane over Palladium Catalysts Supported on Mixed MgF2-MgO Carriers

    Directory of Open Access Journals (Sweden)

    Magdalena Bonarowska

    2016-11-01

    Full Text Available Pd/MgO, Pd/MgF2 and Pd/MgO-MgF2 catalysts were investigated in the reaction of CCl4 hydrodechlorination. All the catalysts deactivated in time on stream, but the degree of deactivation varied from catalyst to catalyst. The MgF2-supported palladium with relatively large metal particles appeared the best catalyst, characterized by good activity and selectivity to C2-C5 hydrocarbons. Investigation of post-reaction catalyst samples allowed to find several details associated with the working state of hydrodechlorination catalysts. The role of support acidity was quite complex. On the one hand, a definite, although not very high Lewis acidity of MgF2 is beneficial for shaping high activity of palladium catalysts. The MgO-MgF2 support characterized by stronger Lewis acidity than MgF2 contributes to very good catalytic activity for a relatively long reaction period (~5 h but subsequent neutralization of stronger acid centers (by coking eliminates them from the catalyst. On the other hand, the role of acidity evolution, which takes place when basic supports (like MgO are chlorided during HdCl reactions, is difficult to assess because different events associated with distribution of chlorided support species, leading to partial or even full blocking of the surface of palladium, which plays the role of active component in HdCl reactions.

  9. Electrochemical performance and durability of carbon supported Pt catalyst in contact with aqueous and polymeric proton conductors.

    Science.gov (United States)

    Andersen, Shuang Ma; Skou, Eivind

    2014-10-08

    Significant differences in catalyst performance and durability are often observed between the use of a liquid electrolyte (e.g., sulfuric acid), and a solid polymer electrolyte (e.g., Nafion). To understand this phenomenon, we studied the electrochemical behavior of a commercially available carbon supported platinum catalyst in four different electrode structures: catalyst powder (CP), catalyst ionomer electrode (CIE), half membrane electrode assembly (HMEA), and full membrane electrode assembly (FMEA) in both ex situ and in situ experiments under a simulated start/stop cycle. We found that the catalyst performance and stability are very much influenced by the presence of the Nafion ionomers. The proton conducting phase provided by the ionomer and the self-assembled electrode structure render the catalysts a higher utilization and better stability. This is probably due to an enhanced dispersion, an improved proton-catalyst interface, the restriction of catalyst particle aggregation, and the improved stability of the ionomer phase especially after the lamination. Therefore, an innovative electrode HMEA design for ex-situ catalyst characterization is proposed. The electrode structure is identical to the one used in a real fuel cell, where the protons transport takes place solely through solid state proton conducting phase.

  10. Nano-stuctured Pt-Fe/C as cathode catalyst in direct methanol fuel cell

    International Nuclear Information System (INIS)

    Li Wenzhen; Zhou Weijiang; Li Huanqiao; Zhou Zhenhua; Zhou Bing; Sun Gongquan; Xin Qin

    2004-01-01

    Pt-Fe/C catalysts were prepared by a modified polyol synthesis method in an ethylene glycol (EG) solution, and then were heat-treated under H 2 /Ar (10 vol.%) at moderate temperature (300 deg. C, Pt-Fe/C300) or high temperature (900 deg. C, Pt-Fe/C900). As comparison, Pt-Fe/C alloy catalyst was prepared by a two-step method (Pt-Fe/C900B). X-ray diffraction (XRD) and transmission electron microscopy (TEM) images show that particles size of the catalyst increases with the increase of treatment temperatures. Pt-Fe/C300 catalyst has a mean particle size of 2.8 nm (XRD), 3.6 nm (TEM) and some Pt-Fe alloy was partly formed in this sample. Pt-Fe/C900B catalyst has the biggest particle size of 6.2 nm (XRD) and the best Pt-Fe alloy form. Cyclicvoltammetry (CV) shows that Pt-Fe/C300 has larger electrochemical surface area than other Pt-Fe/C and the highest utilization ratio of 76% among these Pt-based catalysts. Rotating disk electrode (RDE) cathodic curves show that Pt-Fe/C300 has the highest oxygen reduction reaction (ORR) mass activity (MA) and specific activity (SA), as compared with Pt/C catalyst in 1.0 M HClO 4 . However, Pt-Fe/C catalyst does not appears to be a more active catalyst than Pt/C for ORR in 1.0 M HClO 4 + 0.1 M CH 3 OH. Pt-Fe/C300 exhibits higher ORR activity and better performance than other Pt-Fe/C or Pt/C catalysts when employed for cathode in direct methanol single cell test, the enhancement of the cell performance is logically attributed to its higher ORR activity, which is probably attributed to more Pt 0 species existing and Fe ion corrosion from the catalyst

  11. Iron-57 and iridium-193 Moessbauer spectroscopic studies of supported iron-iridium catalysts

    International Nuclear Information System (INIS)

    Berry, F.J.; Jobson, S.

    1988-01-01

    57 Fe and 193 Ir Moessbauer spectroscopy shows that silica- and alumina-supported iron-iridium catalysts formed by calcination in air contain mixtures of small particle iron(III) oxide and iridium(IV) oxide. The iridium dioxide in both supported catalysts is reduced in hydrogen to metallic iridium. The α-Fe 2 O 3 in the silica supported materials is predominantly reduced in hydrogen to an iron-iridium alloy whilst in the alumina-supported catalyst the iron is stabilised by treatment in hydrogen as iron(II). Treatment of a hydrogen-reduced silica-supported iron catalyst in hydrogen and carbon monoxide is accompanied by the formation of iron carbides. Carbide formation is not observed when the iron-iridium catalysts are treated in similar atmospheres. The results from the bimetallic catalysts are discussed in terms of the hydrogenation of associatively adsorbed carbon monoxide and the selectivity of supported iron-iridium catalysts to methanol formation. (orig.)

  12. Reduction of nanowire diameter beyond lithography limits by controlled catalyst dewetting

    Science.gov (United States)

    Calahorra, Yonatan; Kerlich, Alexander; Amram, Dor; Gavrilov, Arkady; Cohen, Shimon; Ritter, Dan

    2016-04-01

    Catalyst assisted vapour-liquid-solid is the most common method to realize bottom-up nanowire growth; establishing a parallel process for obtaining nanoscale catalysts at pre-defined locations is paramount for further advancement towards commercial nanowire applications. Herein, the effect of a selective area mask on the dewetting of metallic nanowire catalysts, deposited within lithography-defined mask pinholes, is reported. It was found that thin disc-like catalysts, with diameters of 120-450 nm, were transformed through dewetting into hemisphere-like catalysts, having diameters 2-3 fold smaller; the process was optimized to about 95% yield in preventing catalyst splitting, as would otherwise be expected due to their thickness-to-diameter ratio, which was as low as 1/60. The catalysts subsequently facilitated InP and InAs nanowire growth. We suggest that the mask edges prevent surface migration mediated spreading of the dewetted metal, and therefore induce its agglomeration into a single particle. This result presents a general strategy to diminish lithography-set dimensions for NW growth, and may answer a fundamental challenge faced by bottom-up nanowire technology.

  13. SiC nanocrystals as Pt catalyst supports for fuel cell applications

    DEFF Research Database (Denmark)

    Dhiman, Rajnish; Morgen, Per; Skou, E.M.

    2013-01-01

    A robust catalyst support is pivotal to Proton Exchange Membrane Fuel Cells (PEMFCs) to overcome challenges such as catalyst support corrosion, low catalyst utilization and overall capital cost. SiC is a promising candidate material which could be applied as a catalyst support in PEMFCs. Si......C nanocrystals are here synthesized using nano-porous carbon black (Vulcan XC-72) as a template using two different reactions, which result in particle sizes in the ranges of 50-150 nm (SiC-SPR) and 25-35 nm (SiC-NS). Pt nano-catalysts of size 5-8 nm and 4-5 nm have successfully been uniformly deposited...... on the nanocrystals of SiC-SPR and SiC-NS by the polyol method. The SiC substrates are subjected to an acid treatment to introduce the surface groups, which help to anchor the Pt nano-catalysts. These SiC based catalysts have been found to have a higher electrochemical activity than commercially available Vulcan...

  14. Glycerol steam reforming over Ni catalysts supported on ceria and ceria-promoted alumina

    Energy Technology Data Exchange (ETDEWEB)

    Iriondo, A.; Barrio, V.L.; Cambra, J.F.; Arias, P.L.; Guemez, M.B. [School of Engineering, University of the Basque Country (UPV/EHU), c/Alameda Urquijo s/n, 48013 Bilbao (Spain); Sanchez-Sanchez, M.C.; Navarro, R.M.; Fierro, J.L.G. [Institute of Catalysis and Petrochemistry, Spanish Council for Scientific Research (CSIC), c/Marie Curie, 2, Cantoblanco, 28049 Madrid (Spain)

    2010-10-15

    In this paper glycerol steam reforming over Ni catalysts supported on bare CeO{sub 2} and Al{sub 2}O{sub 3}, and CeO{sub 2}-promoted Al{sub 2}O{sub 3} to produce H{sub 2} was studied. The catalytic activity results for the NiAl5Ce and NiAl10Ce catalysts showed that the incorporation of low ceria loadings enhances the activity of the NiAl catalyst prepared using a similar composition to the commercial Ni/Al{sub 2}O{sub 3} catalysts. The catalyst surface characterization revealed that the good behaviour of the NiAl5Ce and the NiAl10Ce catalysts depends on the stabilization of Ni particles which is promoted by the formation of nickel-ceria interactions. The increase of ceria content reduced the capacity of the NiAl20Ce catalyst to convert intermediate oxygenated hydrocarbons into H{sub 2}. (author)

  15. Strange particles

    International Nuclear Information System (INIS)

    Chinowsky, W.

    1989-01-01

    Work done in the mid 1950s at Brookhaven National Laboratory on strange particles is described. Experiments were done on the Cosmotron. The author describes his own and others' work on neutral kaons, lambda and theta particles and points out the theoretical gap between predictions and experimental findings. By the end of the decade, the theory of strange particles was better understood. (UK)

  16. Catalysts for improved fuel processing

    Energy Technology Data Exchange (ETDEWEB)

    Borup, R.L.; Inbody, M.A. [and others

    2000-09-01

    This report covers our technical progress on fuel processing catalyst characterization for the specific purpose of hydrogen production for proton-exchange-membrane (PEM) fuel cells. These development efforts support DOE activities in the development of compact, transient capable reformers for on-board hydrogen generation starting from candidate fuels. The long-term objective includes increased durability and lifetime, in addition to smaller volume, improved performance, and other specifications required meeting fuel processor goals. The technical barriers of compact fuel processor size, transient capability, and compact, efficient thermal management all are functions of catalyst performance. Significantly, work at LANL now tests large-scale fuel processors for performance and durability, as influenced by fuels and fuel constituents, and complements that testing with micro-scale catalyst evaluation which is accomplished under well controlled conditions.

  17. Nanoscale analysis of structural and chemical changes in aged hybrid Pt/NbOx/C fuel cell catalysts

    Science.gov (United States)

    Chinchilla, Lidia; Rossouw, David; Trefz, Tyler; Susac, Darija; Kremliakova, Natalia; Botton, Gianluigi A.

    2017-07-01

    We characterize the structural and chemical changes that take place in an electrochemically tested proton-exchange fuel cell cathode material composed of platinum nanoparticles on a niobium oxide-carbon black hybrid support. Two hybrid catalysts with different niobium oxide content (5 wt% and 12 wt%) are compared at the beginning and end of potential cycling. We observe an overall increase in the particle size of the hybrid catalysts after potential cycling, mediated by Ostwald ripening process. The general nanostructure of the catalysts was composed of small Pt-rich particles that were linked to niobium oxide particles. Nanoscale and microscale spectroscopy of the pristine materials reveals several co-existing oxidized forms of niobium (5+, 4+, 2+) in the systems; the most predominant being Nb(V). The study of the energy loss near-edge structure of the Niobium L2,3 edge of catalysts after being subjected to accelerated stress test (AST) potential cycles provides clues on the evolution of niobium oxides (NbOx), in which the relative distribution of Nb(V) decreases, while the number of Nb particles in lower oxidation states slightly increases. Furthermore, energy-dispersive spectroscopy reveals that the content of Nb decreased after cycling, implying that the loss of NbOx eventually altered the fraction of linked Pt-NbOx sites. The observed nanoscale catalyst changes and the presence of the NbOx may have important implications for developing an alternative design for improved hybrid catalyst materials.

  18. Carbon nanocages: a new support material for Pt catalyst with remarkably high durability.

    Science.gov (United States)

    Wang, Xiao Xia; Tan, Zhe Hua; Zeng, Min; Wang, Jian Nong

    2014-03-24

    Low durability is the major challenge hindering the large-scale implementation of proton exchange membrane fuel cell (PEMFC) technology, and corrosion of carbon support materials of current catalysts is the main cause. Here, we describe the finding of remarkably high durability with the use of a novel support material. This material is based on hollow carbon nanocages developed with a high degree of graphitization and concurrent nitrogen doping for oxidation resistance enhancement, uniform deposition of fine Pt particles, and strong Pt-support interaction. Accelerated degradation testing shows that such designed catalyst possesses a superior electrochemical activity and long-term stability for both hydrogen oxidation and oxygen reduction relative to industry benchmarks of current catalysts. Further testing under conditions of practical fuel cell operation reveals almost no degradation over long-term cycling. Such a catalyst of high activity, particularly, high durability, opens the door for the next-generation PEMFC for "real world" application.

  19. Metal oxides modified NiO catalysts for oxidative dehydrogenation of ethane to ethylene

    KAUST Repository

    Zhu, Haibo

    2014-06-01

    The sol-gel method was applied to the synthesis of Zr, Ti, Mo, W, and V modified NiO based catalysts for the ethane oxidative dehydrogenation reaction. The synthesized catalysts were characterized by XRD, N2 adsorption, SEM and TPR techniques. The results showed that the doping metals could be highly dispersed into NiO domains without the formation of large amount of other bulk metal oxide. The modified NiO materials have small particle size, larger surface area, and higher reduction temperature in contrast to pure NiO. The introduction of group IV, V and VI transition metals into NiO decreases the catalytic activity in ethane ODH. However, the ethylene selectivity is enhanced with the highest level for the Ni-W-O and Ni-Ti-O catalysts. As a result, these two catalysts show improved efficiency of ethylene production in the ethane ODH reaction. © 2014 Elsevier B.V. All rights reserved.

  20. Decomposition kinetics of ammonia in gaseous stream by a nanoscale copper-cerium bimetallic catalyst.

    Science.gov (United States)

    Hung, Chang-Mao

    2008-01-15

    This study performance is to examine the kinetics over nanoscale copper-cerium bimetallic catalyst under selective catalytic oxidation (SCO) of ammonia to N(2) in a tubular fixed-bed reactor (TFBR) at temperatures from 150 to 400 degrees C in the presence of oxygen. The nanoscale copper-cerium bimetallic catalyst was prepared by co-precipitation with Cu(NO(3))(2) and Ce(NO(3))(3) at molar ratio of 6:4. Experimental results showed that the catalyst with transmission electron microscopy (TEM) revealed that copper and cerium are well dispersed and catalyst in the form of nanometer-sized particles. Moreover, the kinetic behavior of NH(3) oxidation with catalysis can be accounted by using the rate expression of the Langmuir-Hinshelwood type kinetic model. Kinetic parameters are also developed on the basis of the differential reactor data. Also, experimental results are compared with those of the model predicted.

  1. Carbon nanocages: A new support material for Pt catalyst with remarkably high durability

    Science.gov (United States)

    Wang, Xiao Xia; Tan, Zhe Hua; Zeng, Min; Wang, Jian Nong

    2014-01-01

    Low durability is the major challenge hindering the large-scale implementation of proton exchange membrane fuel cell (PEMFC) technology, and corrosion of carbon support materials of current catalysts is the main cause. Here, we describe the finding of remarkably high durability with the use of a novel support material. This material is based on hollow carbon nanocages developed with a high degree of graphitization and concurrent nitrogen doping for oxidation resistance enhancement, uniform deposition of fine Pt particles, and strong Pt-support interaction. Accelerated degradation testing shows that such designed catalyst possesses a superior electrochemical activity and long-term stability for both hydrogen oxidation and oxygen reduction relative to industry benchmarks of current catalysts. Further testing under conditions of practical fuel cell operation reveals almost no degradation over long-term cycling. Such a catalyst of high activity, particularly, high durability, opens the door for the next-generation PEMFC for “real world” application. PMID:24658614

  2. Method of synthesizing bulk transition metal carbide, nitride and phosphide catalysts

    Science.gov (United States)

    Choi, Jae Soon; Armstrong, Beth L; Schwartz, Viviane

    2015-04-21

    A method for synthesizing catalyst beads of bulk transmission metal carbides, nitrides and phosphides is provided. The method includes providing an aqueous suspension of transition metal oxide particles in a gel forming base, dropping the suspension into an aqueous solution to form a gel bead matrix, heating the bead to remove the binder, and carburizing, nitriding or phosphiding the bead to form a transition metal carbide, nitride, or phosphide catalyst bead. The method can be tuned for control of porosity, mechanical strength, and dopant content of the beads. The produced catalyst beads are catalytically active, mechanically robust, and suitable for packed-bed reactor applications. The produced catalyst beads are suitable for biomass conversion, petrochemistry, petroleum refining, electrocatalysis, and other applications.

  3. Nano carbon supported platinum catalyst interaction behavior with perfluorosulfonic acid ionomer and their interface structures

    DEFF Research Database (Denmark)

    Andersen, Shuang Ma

    2016-01-01

    The interaction between perfluorosulfonic acid ionomer and supported platinum catalyst is essential. It directly influences platinum accessibility, stability of carbon support and platinum, proton conductivity and electron conductivity in an electrode. In this study, we compare the adsorption......, the ionomer may have an adsorption preference to the platinum nano particle rather than to the overall catalyst. This was verified by a close examination on the decomposition temperature of the carbon support and the ionomer. The electrochemical stability of the catalyst ionomer composite electrode suggests...... behavior of Nafion ionomer on platinized carbon nano fibers (CNFs), carbon nano tubes (CNTs) and amorphous carbon (Vulcan). The interaction is affected by the catalyst surface oxygen groups as well as porosity. Comparisons between the carbon supports and platinized equivalents are carried out. It reveals...

  4. Handling of Solid Residues

    International Nuclear Information System (INIS)

    Medina Bermudez, Clara Ines

    1999-01-01

    The topic of solid residues is specifically of great interest and concern for the authorities, institutions and community that identify in them a true threat against the human health and the atmosphere in the related with the aesthetic deterioration of the urban centers and of the natural landscape; in the proliferation of vectorial transmitters of illnesses and the effect on the biodiversity. Inside the wide spectrum of topics that they keep relationship with the environmental protection, the inadequate handling of solid residues and residues dangerous squatter an important line in the definition of political and practical environmentally sustainable. The industrial development and the population's growth have originated a continuous increase in the production of solid residues; of equal it forms, their composition day after day is more heterogeneous. The base for the good handling includes the appropriate intervention of the different stages of an integral administration of residues, which include the separation in the source, the gathering, the handling, the use, treatment, final disposition and the institutional organization of the administration. The topic of the dangerous residues generates more expectation. These residues understand from those of pathogen type that are generated in the establishments of health that of hospital attention, until those of combustible, inflammable type, explosive, radio-active, volatile, corrosive, reagent or toxic, associated to numerous industrial processes, common in our countries in development

  5. Hydrodesulfurization and hydrodemetallization of different origin vacuum residues : new modeling approach.

    OpenAIRE

    Ferreira , Cristina; Tayakout-Fayolle , Melaz; Guibard , Isabelle; Lemos , Francisco

    2014-01-01

    International audience; In order to be able to upgrade the heaviest part of the crude oil one needs to remove several impurities, such as sulfur or metals. Residue hydrotreatment in fixed beds, under high hydrogen pressure can achieve high removal performances, with an industrial catalysts optimized staging. Despite the recent improvements, petroleum residues remain very difficult to describe and characterize in detail. Several kinetic models have been developed, but mostly they are feed depe...

  6. Use of lanthanide catalysts in air electrodes

    International Nuclear Information System (INIS)

    Souza Parente, L.T. de

    1982-01-01

    A review on the lanthanide catalysts suitable for the reduction catalysis of oxygen in air electrodes is presented. The kinds of lanthanide indicated to be used as catalysts of oxygen reduction are shown. (A.R.H.) [pt

  7. Catalyst for Decomposition of Nitrogen Oxides

    Science.gov (United States)

    Schryer, David R. (Inventor); Jordan, Jeffrey D. (Inventor); Akyurtlu, Ates (Inventor); Akyurtlu, Jale (Inventor)

    2015-01-01

    This invention relates generally to a platinized tin oxide-based catalyst. It relates particularly to an improved platinized tin oxide-based catalyst able to decompose nitric oxide to nitrogen and oxygen without the necessity of a reducing gas.

  8. Novel Fischer-Tropsch catalysts. [DOE patent

    Science.gov (United States)

    Vollhardt, K.P.C.; Perkins, P.

    Novel compounds are described which are used as improved Fischer-Tropsch catalysts particularly for the conversion of CO + H/sub 2/ to gaseous and liquid hydrocarbons at milder conditions than with prior catalysts.

  9. Paraffin Alkylation Using Zeolite Catalysts in a slurry reactor: Chemical Engineering Principles to Extend Catalyst Lifetime

    NARCIS (Netherlands)

    Jong, K.P. de; Mesters, C.M.A.M.; Peferoen, D.G.R.; Brugge, P.T.M. van; Groot, C. de

    1996-01-01

    The alkylation of isobutane with 2-butene is carried out using a zeolitic catalyst in a well stirred slurry reactor. Whereas application of fixed bed technology using a solid acid alkylation catalyst has in the led to catalysts lifetimes in the range of minutes, in this work we report catalyst

  10. Quick Guide to Flash Catalyst

    CERN Document Server

    Elmansy, Rafiq

    2011-01-01

    How do you transform user interface designs created in Photoshop or Illustrator into interactive web pages? It's easier than you think. This guide shows you how to use Adobe Flash Catalyst to create interactive UIs and website wireframes for Rich Internet Applications-without writing a single line of code. Ideal for web designers, this book introduces Flash Catalyst basics with detailed step-by-step instructions and screenshots that illustrate every part of the process. You'll learn hands-on how to turn your static design or artwork into working user interfaces that can be implemented in Fla

  11. Hydrothermal performance of catalyst supports

    Energy Technology Data Exchange (ETDEWEB)

    Elam, Jeffrey W.; Marshall, Christopher L.; Libera, Joseph A.; Dumesic, James A.; Pagan-Torres, Yomaira J.

    2018-04-10

    A high surface area catalyst with a mesoporous support structure and a thin conformal coating over the surface of the support structure. The high surface area catalyst support is adapted for carrying out a reaction in a reaction environment where the thin conformal coating protects the support structure within the reaction environment. In various embodiments, the support structure is a mesoporous silica catalytic support and the thin conformal coating comprises a layer of metal oxide resistant to the reaction environment which may be a hydrothermal environment.

  12. Catalysts for cleaner combustion of coal, wood and briquettes sulfur dioxide reduction options for low emission sources

    Energy Technology Data Exchange (ETDEWEB)

    Smith, P.V. [Global Environmental Solutions, Inc., Morton Grove, IL (United States)

    1995-12-31

    Coal fired, low emission sources are a major factor in the air quality problems facing eastern European cities. These sources include: stoker-fired boilers which feed district heating systems and also meet local industrial steam demand, hand-fired boilers which provide heat for one building or a small group of buildings, and masonary tile stoves which heat individual rooms. Global Environmental Systems is marketing through Global Environmental Systems of Polane, Inc. catalysts to improve the combustion of coal, wood or fuel oils in these combustion systems. PCCL-II Combustion Catalysts promotes more complete combustion, reduces or eliminates slag formations, soot, corrosion and some air pollution emissions and is especially effective on high sulfur-high vanadium residual oils. Glo-Klen is a semi-dry powder continuous acting catalyst that is injected directly into the furnace of boilers by operating personnel. It is a multi-purpose catalyst that is a furnace combustion catalyst that saves fuel by increasing combustion efficiency, a cleaner of heat transfer surfaces that saves additional fuel by increasing the absorption of heat, a corrosion-inhibiting catalyst that reduces costly corrosion damage and an air pollution reducing catalyst that reduces air pollution type stack emissions. The reduction of sulfur dioxides from coal or oil-fired boilers of the hand fired stoker design and larger, can be controlled by the induction of the Glo-Klen combustion catalyst and either hydrated lime or pulverized limestone.

  13. Overcoming the Instability of Nanoparticle-Based Catalyst Films in Alkaline Electrolyzers by using Self-Assembling and Self-Healing Films.

    Science.gov (United States)

    Barwe, Stefan; Masa, Justus; Andronescu, Corina; Mei, Bastian; Schuhmann, Wolfgang; Ventosa, Edgar

    2017-07-10

    Engineering stable electrodes using highly active catalyst nanopowders for electrochemical water splitting remains a challenge. We report an innovative and general approach for attaining highly stable catalyst films with self-healing capability based on the in situ self-assembly of catalyst particles during electrolysis. The catalyst particles are added to the electrolyte forming a suspension that is pumped through the electrolyzer. Particles with negatively charged surfaces stick onto the anode, while particles with positively charged surfaces stick to the cathode. The self-assembled catalyst films have self-healing properties as long as sufficient catalyst particles are present in the electrolyte. The proof-of-concept was demonstrated in a non-zero gap alkaline electrolyzer using NiFe-LDH and Ni x B catalyst nanopowders for anode and cathode, respectively. Steady cell voltages were maintained for at least three weeks during continuous electrolysis at 50-100 mA cm -2 . © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Stereospecific olefin polymerization with chiral metallocene catalysts

    OpenAIRE

    Brintzinger, Hans-Herbert; Fischer, David; Mülhaupt, Rolf; Rieger, Bernhard; Waymouth, Robert M.

    1995-01-01

    Current studies on novel, metallocenebased catalysts for the polymerization of α-olefins have far-reaching implications for the development of new materials as well as for the understanding of basic reaction mechanisms responsible for the growth of a polymer chain at a catalyst center and the control of its stereoregularity. In contrast to heterogeneous Ziegler–Natta catalysts, polymerization by a homogeneous, metallocene-based catalyst occurs principally at a single type of metal center with...

  15. Rare behaviour of a catalyst pellet catalyst dynamics

    NARCIS (Netherlands)

    Westerterp, K.R.; Loonen, R.A.; Martens, A.

    1986-01-01

    Temperature overshoots and undershoots were found for a Pd on alumina catalyst pellet in its course towards a new steady state after a change in concentration of one of the reactants ethylene or hydrogen. When cooling the pellet, after heat-up by reaction, with pure hydrogen a sudden temperature

  16. Theoretical modeling of structure and function of cathode catalyst layers in PEMFC

    International Nuclear Information System (INIS)

    Wang, Q.; Eikerling, M.; Song, D.; Liu, Z.

    2004-01-01

    'Full text:' In this work, we first investigate transport and reaction kinetics in single agglomerates of cathode catalyst layers in proton exchange fuel cells. Two types of spherical agglomerates are evaluated, which represent limiting structures that can be obtained by distinct synthetic procedures. One type consists of a mixture of carbon/catalyst particles and proton conducting perfluorosulfonated ionomer (PFSI). The other type consists of carbon/catalyst particles and water-filled pores. Performance of the former type is rationalized on the basis of the well-known Thiele-modulus. Characteristics of the latter type are studied using Nernst-Planck and Poisson equations. Aspects of current conversion, reactant and current distributions, and catalyst utilization are explored. In general, the PFSI-filled agglomerates exhibit more homogeneous distributions of reaction rates. Effectiveness factors for them are close to one. However, it was found that proton penetration depths in waterflooded agglomerates could be quite significant as well under certain conditions, resulting in unexpectedly high catalyst utilization. The effects of agglomerate radius and of boundary conditions at the agglomerate surface are studied. Moreover, using the same approach, we evaluate the performance of a flat PFSI-free catalyst layer with water-filled pore space. Compared with conventional composite catalyst layers impregnated with PFSI, the PFSI-free layer exhibits better performance and high Pt utilization for thicknesses less than 0.1 μm. The significance of these results for the optimization catalyst layers in view of operation conditions and synthesis methods is discussed. (author)

  17. Ultrasound assisted synthesis of iron doped TiO2 catalyst.

    Science.gov (United States)

    Ambati, Rohini; Gogate, Parag R

    2018-01-01

    The present work deals with synthesis of Fe (III) doped TiO 2 catalyst using the ultrasound assisted approach and conventional sol-gel approach with an objective of establishing the process intensification benefits. Effect of operating parameters such as Fe doping, type of solvent, solvent to precursor ratio and initial temperature has been investigated to get the best catalyst with minimum particle size. Comparison of the catalysts obtained using the conventional and ultrasound assisted approach under the optimized conditions has been performed using the characterization techniques like DLS, XRD, BET, SEM, EDS, TEM, FTIR and UV-Vis band gap analysis. It was established that catalyst synthesized by ultrasound assisted approach under optimized conditions of 0.4mol% doping, irradiation time of 60min, propan-2-ol as the solvent with the solvent to precursor ratio as 10 and initial temperature of 30°C was the best one with minimum particle size as 99nm and surface area as 49.41m 2 /g. SEM analysis, XRD analysis as well as the TEM analysis also confirmed the superiority of the catalyst obtained using ultrasound assisted approach as compared to the conventional approach. EDS analysis also confirmed the presence of 4.05mol% of Fe element in the sample of 0.4mol% iron doped TiO 2 . UV-Vis band gap results showed the reduction in band gap from 3.2eV to 2.9eV. Photocatalytic experiments performed to check the activity also confirmed that ultrasonically synthesized Fe doped TiO 2 catalyst resulted in a higher degradation of Acid Blue 80 as 38% while the conventionally synthesized catalyst resulted in a degradation of 31.1%. Overall, the work has clearly established importance of ultrasound in giving better catalyst characteristics as well as activity for degradation of the Acid Blue 80 dye. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. 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.

  19. Photocatalytic degradation of nicotine in an aqueous solution using unconventional supported catalysts and commercial ZnO/TiO{sub 2} under ultraviolet radiation

    Energy Technology Data Exchange (ETDEWEB)

    Franco, Marcela Andrea Espina de, E-mail: marcela.eq@gmail.com; Silva, William Leonardo da; Bagnara, Mônica; Lansarin, Marla Azário; Zimnoch dos Santos, João Henrique

    2014-10-01

    Nicotine, a highly toxic alkaloid, has been detected in effluents, surface and groundwater and even bottled mineral water. The present work studied the photocatalytic degradation of nicotine in aqueous solution, under ultraviolet irradiation. The experiments were carried out using commercial (ZnO, TiO{sub 2}) and non-conventional catalysts, which were prepared from industrial and laboratory waste. Two experimental designs (CCD) were performed for both commercial catalysts, and initial nicotine concentration, catalyst concentration and initial solution pH effects were studied. Then, the synthesized catalysts were tested under the optimal conditions which were found through CCDs. Using commercial catalysts, about 98% of the alkaloid was degraded by ZnO, and 88% by TiO{sub 2}, in 1 h. Among the non-conventional catalysts, the highest photocatalytic degradation (44%) was achieved using the catalyst prepared from a petrochemical industry residue. - Highlights: • The photocatalytic degradation of nicotine was studied under UV irradiation. • Commercial catalysts ZnO and TiO{sub 2} were tested using two central composite designs. • Initial nicotine concentration, catalyst concentration and pH were evaluated. • Catalysts were prepared using chemical wastes and tested at the best conditions.

  20. Photocatalytic degradation of nicotine in an aqueous solution using unconventional supported catalysts and commercial ZnO/TiO2 under ultraviolet radiation

    International Nuclear Information System (INIS)

    Franco, Marcela Andrea Espina de; Silva, William Leonardo da; Bagnara, Mônica; Lansarin, Marla Azário; Zimnoch dos Santos, João Henrique

    2014-01-01

    Nicotine, a highly toxic alkaloid, has been detected in effluents, surface and groundwater and even bottled mineral water. The present work studied the photocatalytic degradation of nicotine in aqueous solution, under ultraviolet irradiation. The experiments were carried out using commercial (ZnO, TiO 2 ) and non-conventional catalysts, which were prepared from industrial and laboratory waste. Two experimental designs (CCD) were performed for both commercial catalysts, and initial nicotine concentration, catalyst concentration and initial solution pH effects were studied. Then, the synthesized catalysts were tested under the optimal conditions which were found through CCDs. Using commercial catalysts, about 98% of the alkaloid was degraded by ZnO, and 88% by TiO 2 , in 1 h. Among the non-conventional catalysts, the highest photocatalytic degradation (44%) was achieved using the catalyst prepared from a petrochemical industry residue. - Highlights: • The photocatalytic degradation of nicotine was studied under UV irradiation. • Commercial catalysts ZnO and TiO 2 were tested using two central composite designs. • Initial nicotine concentration, catalyst concentration and pH were evaluated. • Catalysts were prepared using chemical wastes and tested at the best conditions

  1. Ethylene hydrogenation over catalysts formed by oxidation of intermetallic compounds

    International Nuclear Information System (INIS)

    Imamura, H.; Wallace, W.E.

    1980-01-01

    The intermetallic compounds (LaNi 5 , CeNi 5 , PrNi 5 , ThNi 5 , ThFe 5 , and ThCo 5 ) readily react with oxygen. Examination of the oxidized materials by using x-ray diffraction showed that they consisted of a mixture of transition metal and rare earth oxide (or ThO 2 ). The transition metals exhibited particle sizes ranging from 90 to 350A, as estimated by x-ray diffraction line broadening. These mixtures exhibited high catalytic activity for the hydrogenation of ethylene compared to oxide-supported catalysts prepared by the conventional impregnation method, with turnover frequencies higher for the former materials by an order of magnitude. The oxidation process is a novel means of producing very active supported catalysts

  2. Fabrication of a thin catalyst layer using organic solvents

    Science.gov (United States)

    Yang, Tae-Hyun; Yoon, Young-Gi; Park, Gu-Gon; Lee, Won-Yong; Kim, Chang-Soo

    The effects of various organic solvents on the performance of polymer electrolyte membrane fuel cell (PEMFC) electrode were investigated. The five catalyst inks were prepared by mixing the 20 wt.% Pt/C, 5 wt.% solubilized Nafion, tetrabutylammonium hydroxide (TBAOH), and different organic solvents such as normal butyl acetate, iso-amyl alcohol, diethyl oxalate, ethylene glycol and ethylene glycol dimethyl ether. Membrane electrode assemblies were prepared by using a transfer method. From the measurements of performances of single cells, the most suitable solvent was selected and the results were discussed in terms of distribution of Nafion ionomer on Pt particles and robustness of the catalyst structure. In addition, reactant transport through electrodes was discussed in relation with decomposition of the solvents.

  3. Well-defined iron complexes as efficient catalysts for "green" atom-transfer radical polymerization of styrene, methyl methacrylate, and butyl acrylate with low catalyst loadings and catalyst recycling.

    Science.gov (United States)

    Nakanishi, So-Ichiro; Kawamura, Mitsunobu; Kai, Hidetomo; Jin, Ren-Hua; Sunada, Yusuke; Nagashima, Hideo

    2014-05-05

    Environmentally friendly iron(II) catalysts for atom-transfer radical polymerization (ATRP) were synthesized by careful selection of the nitrogen substituents of N,N,N-trialkylated-1,4,9-triazacyclononane (R3 TACN) ligands. Two types of structures were confirmed by crystallography: "[(R3 TACN)FeX2 ]" complexes with relatively small R groups have ionic and dinuclear structures including a [(R3 TACN)Fe(μ-X)3 Fe(R3 TACN)](+) moiety, whereas those with more bulky R groups are neutral and mononuclear. The twelve [(R3 TACN)FeX2 ]n complexes that were synthesized were subjected to bulk ATRP of styrene, methyl methacrylate (MMA), and butyl acrylate (BA). Among the iron complexes examined, [{(cyclopentyl)3 TACN}FeBr2 ] (4 b) was the best catalyst for the well-controlled ATRP of all three monomers. This species allowed easy catalyst separation and recycling, a lowering of the catalyst concentration needed for the reaction, and the absence of additional reducing reagents. The lowest catalyst loading was accomplished in the ATRP of MMA with 4 b (59 ppm of Fe based on the charged monomer). Catalyst recycling in ATRP with low catalyst loadings was also successful. The ATRP of styrene with 4 b (117 ppm Fe atom) was followed by precipitation from methanol to give polystyrene that contained residual iron below the calculated detection limit (0.28 ppm). Mechanisms that involve equilibria between the multinuclear and mononuclear species were also examined. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Removable Water-Soluble Olefin Metathesis Catalyst via Host-Guest Interaction.

    Science.gov (United States)

    Kim, Cheoljae; Ondrusek, Brian A; Chung, Hoyong

    2018-02-02

    A highly removable N-heterocyclic carbene ligand for a transition-metal catalyst in aqueous media via host-guest interactions has been developed. Water-soluble adamantyl tethered ethylene glycol in the ligand leads a hydrophobic inclusion into the cavity of β-cyclodextrin. Ruthenium (Ru) olefin metathesis catalyst with this ligand demonstrated excellent performance in various metathesis reactions in water as well as in CH 2 Cl 2 , and removal of residual Ru was performed via filtration utilizing a host-guest interaction and extraction.

  5. Influence of alkali catalyst on product yield and properties via hydrothermal liquefaction of barley straw

    DEFF Research Database (Denmark)

    Zhu, Z.; Toor, Saqib; Rosendahl, Lasse

    2015-01-01

    Barley straw was successfully converted to bio-crude by hydrothermal liquefaction at temperature of 280 e400 C using an alkali catalyst (K2CO3) in our previous work, and the maximum bio-crude yield was obtained at 300 C. This paper extends previous work on studying liquefaction behavior of barley...... straw without and with K2CO3 at 300 C. The effect of alkali catalyst on product distribution was investigated, and a detailed analysis of characteristic properties of bio-crude and solid residue has been performed by an elemental analyzer, FTIR (Fourier Transform infrared spectroscopy), TGA...

  6. Fate and Transport of Colloidal Energetic Residues

    Science.gov (United States)

    2015-07-01

    field) images of (b) a single and (c) an aggregated particle in the experimental solution . .............................................. 19  Figure...84  vii ACRONYM LIST ARW artificial rainwater °C degree Celsius cm centimeter d day DNX hexahydro-1,3-dinitroso-5- nitro ...munition constituents. This size fraction of residues had not been studied in any detail, yet it represents the most mobile and most rapidly

  7. 40 CFR 721.9665 - Organotin catalysts.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Organotin catalysts. 721.9665 Section... Substances § 721.9665 Organotin catalysts. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substances identified generically as organotin catalysts (PMNs P-93-853, P-93...

  8. Catalysts and methods of using the same

    Energy Technology Data Exchange (ETDEWEB)

    Slowing, Igor Ivan; Kandel, Kapil

    2017-02-14

    The present invention provides a catalyst including a mesoporous silica nanoparticle and a catalytic material comprising iron. In various embodiments, the present invention provides methods of using and making the catalyst. In some examples, the catalyst can be used to hydrotreat fatty acids or to selectively remove fatty acids from feedstocks.

  9. Efficient epoxidation of propene using molecular catalysts

    DEFF Research Database (Denmark)

    Markovits, Iulius I. E.; Anthofer, Michael H.; Kolding, Helene

    2014-01-01

    The epoxidation of propene is performed in homogeneous phase using various molecular catalysts and H2O2 or tert-butyl hydroperoxide as oxidants. A comparison between some molybdenum catalysts and methyltrioxorhenium (MTO) shows that the well known Re catalyst is the best among the examined...

  10. Novel non-platinum metal catalyst material

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to a novel non-platinum metal catalyst material for use in low temperature fuel cells and electrolysers and to fuel cells and electrolysers comprising the novel non-platinum metal catalyst material. The present invention also relates to a novel method for synthesizing...... the novel non-platinum metal catalyst material....

  11. Low platinum catalyst and method of preparation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Di-Jia; Chong, Lina

    2017-11-21

    A low platinum catalyst and method for making same. The catalyst comprises platinum-transition metal bimetallic alloy microcrystallites over a transition metal-nitrogen-carbon composite. A method of making a catalyst comprises preparation of transition metal organic frameworks, infusion of platinum, thermal treatment, and reduction to form the microcrystallites and composite.

  12. Alternative alkali resistant deNOx catalysts

    DEFF Research Database (Denmark)

    Putluru, Siva Sankar Reddy; Kristensen, Steffen Buus; Due-Hansen, Johannes

    2012-01-01

    Alternative alkali resistant deNOx catalysts were prepared using three different supports ZrO2, TiO2 and Mordenite zeolite. The majority of the catalysts were prepared by incipient wetness impregnation of a commercial support, with vanadium, copper or iron precursor, one catalyst was prepared...

  13. Reconstruction of particle size distributions and anisometry in polydisperse systems by the small-angle scattering method

    International Nuclear Information System (INIS)

    Plavnik, G.M.

    1986-01-01

    A technique to obtain particle size distributions from small-angle scattering data is suggested. It is applicable to systems of particles of arbitrary but identical shape, roughly equiaxial particles of various shapes, and particles of unknown shape. The procedure involved in the determination of the micropore sizes in Pt+Al 2 O 3 catalysts is demonstrated. (author)

  14. Effect of Pretreatment with Sulfuric Acid on Catalytic Hydrocracking of Fe/AC Catalysts

    Directory of Open Access Journals (Sweden)

    Ruiyu Wang

    2017-01-01

    Full Text Available Activated carbon (AC was modified by H2SO4 and used as a support for catalyst. The Fe2S3/AC-T catalyst was prepared by deposition-precipitation method and used to catalyze hydrocracking of coal-related model compound, di(1-naphthylmethane (DNM. The properties of catalyst were studied by N2 adsorption-desorption, X-ray diffraction, and scanning electron microscopy. The result showed that ferric sulfate and acidic centers had synergetic effect on hydrocracking of DNM when using Fe2S3/AC-T as catalyst, the optimal loading of Fe is 9 wt.%. Hydroconversion of the extraction residue from Guizhou bituminous coal was also studied using Fe2S3/AC-T as the catalyst. The reaction was conducted in cyclohexane under 0.8 Mpa of initial hydrogen pressure at 310°C. The reaction mixture was extracted with petroleum ether and analyzed by GC/MS. Amounts of organic compounds which fall into the categories of homologues of benzene and naphthalene were detected. It suggested that the catalyst could effectively catalyze the cleavage of C-C-bridged bonds.

  15. The modification of ion exchange heterogeneous catalysts for biodiesel synthesis

    Science.gov (United States)

    Hartono, R.; Mulia, B.; Sahlan, M.; Utami, T. S.; Wijanarko, Anondho; Hermansyah, Heri

    2017-03-01

    Conventionally, biodiesel is produced by using the homogeneous catalyst which has difficulty in high cost of the separation process. The heterogeneous catalysts ion exchange resin by its Solid phase can make an easier separation process, able to be reactivated and used repeatedly. In this research, the heterogeneous catalyst from various source such as Lewatit macro porous resin, Amberlite gel resin and natural zeolite bayah was investigated their performance to produced biodiesel from used cooking oil. Initially, the preparation of the ion exchange process with variations in time, temperature, the concentration of HCl and NaOH solution was investigated. Then, the activity of heterogeneous catalyst to produced biodiesel under the variation of stirring rate, zeolite particle size, and comparison of different ion exchange catalysts were also investigated. Finally, the stability test and regeneration treatment were also investigated. The optimum operating conditions of biodiesel synthesis process is at the temperature of 60 °C for 2 h with a stirring speed of 700 rpm. Natural zeolite Bayah with 6 M of NaOH solution produced 16.19%, Amberlite gel with 6 M HCL produced 65.22% of biodiesel yield and material Lewatit macro porous with 6 M of NaOH solution produced 85.94% as the maximum result. As the best result, Material Lewatit macro porous selected as the material which was used in the variation of stirring speed, temperature, and reaction time, the concentration of base and stability test. According to the results of analysis, calculations yield methyl oleic HPLC produced by Lewatit macro porous with 6 M NaOH at 62.95%.

  16. Heat and Mass Transfer in a Reforming Catalyst Bed: Quantitative Evaluation of the Controlling Factor by Experiment

    Science.gov (United States)

    Usami, Yutaka; Fukusako, Shoichiro; Yamada, Masahiko

    Heat and mass transfer characteristics in a reforming catalyst bed have been experimentally investigated. Experiments were carried out with a single bench-scaled reforming tube which was filled with reforming catalyst. The tube wall was uniformly heated, and mixtures of steam and methane or propane were reformed through the catalyst bed. Most part of the reaction was completed in the upper part of the test tube. The effects of space velocity, which is a ratio of volumetric flow rate of process gas to the catalyst volume, steam carbon molar ratio, wall temperature, bed temperature, and catalyst particle diameter on the transport phenomena with chemical reaction, were determined. A correlation to heat transfer coefficient was determined by Nu, Rep, Pr, dp/d, and Da. The prediction of the overall methane conversion rate was also presented.

  17. Does Pelletizing Catalysts Influence the Efficiency Number of Activity Measurements? Spectrochemical Engineering Considerations for an Accurate Operando Study

    DEFF Research Database (Denmark)

    Rasmussen, Søren Birk; Perez-Ferreras, Susana; Banares, Miguel A.

    2013-01-01

    of, for example, support oxides might take place, which in turn affects the pore size distribution and the porosity of the catalyst, leading to the observation of lower activity values due to decreased catalyst efficiency. This phenomenon can also apply to conventional activity measurements......, in the cases that pelletizing and recrushing of samples are performed to obtain adequate particle size fractions for the catalytic bed. A case study of an operand investigation of a V2O3-WO3/TiO2-sepiolite catalyst is used as an example, and simple calculations of the influence of catalyst activity...... and internal pore diffusion properties are considered in this paper for the evaluation of catalyst performance in, for example, operando reactors. Thus, it is demonstrated that with a pelletizing pressure of...

  18. Influence of noble metals on the performance of Co/SiO{sub 2} catalyst for 1-hexene hydroformylation

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, X.Q.; Tsubaki, N.; Sun, S.L.; Fujimoto, K. [Tsing Hua University, Beijing (China). Dept. of Chemistry, State Key Laboratory of C1 Chemistry of Technology

    2002-08-01

    Effect of small amount of Pt, Pd and Ru promoters on the characteristics and performance of Co/SiO{sub 2} catalyst, which was prepared from the mixture of cobalt nitrate and cobalt acetate, was investigated in the hydroformylation of 1-hexene. It was found that the addition of small amount of a noble metal to the supported cobalt catalyst led into great improvement of catalyst activity for hydroformylation of 1-hexene. The 1-hexene conversion as high as 89.7% and oxygenate products selectivity of 88.9% were obtained after reaction of 2 h over Pd promoted CO/SiO{sub 2} catalyst. The increasing of reduction degree, the minimizing of cobalt particle size and the enhancement of carbonyl and linear CO adsorption were responsible for the improved performance of the catalyst. 19 refs., 3 figs., 3 tabs.

  19. Population and hierarchy of active species in gold iron oxide catalysts for carbon monoxide oxidation

    Science.gov (United States)

    He, Qian; Freakley, Simon J.; Edwards, Jennifer K.; Carley, Albert F.; Borisevich, Albina Y.; Mineo, Yuki; Haruta, Masatake; Hutchings, Graham J.; Kiely, Christopher J.

    2016-01-01

    The identity of active species in supported gold catalysts for low temperature carbon monoxide oxidation remains an unsettled debate. With large amounts of experimental evidence supporting theories of either gold nanoparticles or sub-nm gold species being active, it was recently proposed that a size-dependent activity hierarchy should exist. Here we study the diverging catalytic behaviours after heat treatment of Au/FeOx materials prepared via co-precipitation and deposition precipitation methods. After ruling out any support effects, the gold particle size distributions in different catalysts are quantitatively studied using aberration corrected scanning transmission electron microscopy (STEM). A counting protocol is developed to reveal the true particle size distribution from HAADF-STEM images, which reliably includes all the gold species present. Correlation of the populations of the various gold species present with catalysis results demonstrate that a size-dependent activity hierarchy must exist in the Au/FeOx catalyst. PMID:27671143

  20. Carbon nanostructures as catalyst support for polymer electrolyte membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Natarajan, S.K.; Hamelin, J. [Quebec Univ., Trois Rivieres, PQ (Canada). Inst. de recherche sur l' hydrogene

    2008-07-01

    This paper reported on a study that investigated potential alternatives to Vulcan XC-72 as a catalyst supports for polymer electrolyte membrane fuel cells (PEMFCs). These included carbon nanostructures (CNS) prepared by high energy ball milling of graphite and transition metal catalysts, followed by heat treatment. Among the key factors discussed were the graphitic content, high surface area, microporous structure, good electrical conductivity and the ability of the material to attach functional groups. Some graphic results supporting the usage of CNS as catalyst support for PEMFCs were presented. Upon chemical oxidation, surface functional groups such as carbonyl, carboxyl, and hydroxyl were populated on the surface of CNS. Nanosized platinum particles with particle size distribution between 3 nm and 5 nm were reduced on the functionalized sites of CNS in a colloidal medium. The paper also presented cyclic voltammograms, XPS, HRTEM and PSD results. 3 refs.