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Sample records for tetraphenylborate catalyst studies

  1. (Butoxymethylidenedimethylazanium tetraphenylborate acetonitrile monosolvate

    Directory of Open Access Journals (Sweden)

    Ioannis Tiritiris

    2014-04-01

    Full Text Available In the title solvated salt, C7H16NO+·C24H20B−·C2H3N, the C—N bond lengths in the cation are 1.2831 (19, 1.467 (2 and 1.465 (2 Å, indicating double- and single-bond character, respectively. The C—O bond length of 1.2950 (18 Å shows a double-bond character, pointing towards charge delocalization within the NCO plane of the iminium ion. The two C atoms of the n-butyl group are disordered over the two sites, with refined occupancy ratios of 0.890 (5:0.110 (5 and 0.888 (4:0.112 (4. In the crystal, C—H...π interactions occur between the methine H atom, H atoms of the –N(CH32 and –CH2 groups of the cation, and two of the phenyl rings of the tetraphenylborate anion. The latter interaction forms an aromatic pocket in which the cation is embedded. Thus, a two-dimensional pattern is created in the ac plane.

  2. USING WET AIR OXIDATION TECHNOLOGY TO DESTROY TETRAPHENYLBORATE

    Energy Technology Data Exchange (ETDEWEB)

    Adu-Wusu, K; Daniel McCabe, D; Bill Wilmarth, B

    2007-04-04

    A bench-scale feasibility study on the use of a Wet Air Oxidation (WAO) process to destroy a slurry laden with tetraphenylborate (TPB) compounds has been undertaken. WAO is an aqueous phase process in which soluble and/or insoluble waste constituents are oxidized using oxygen or oxygen in air at elevated temperatures and pressures ranging from 150 C and 1 MPa to 320 C and 22 MPa. The products of the reaction are CO{sub 2}, H{sub 2}O, and low molecular weight oxygenated organics (e.g. acetate, oxalate). Test results indicate WAO is a feasible process for destroying TPB, its primary daughter products [triphenylborane (3PB), diphenylborinic acid (2PB), and phenylboronic acid (1PB)], phenol, and most of the biphenyl byproduct. The required conditions are a temperature of 300 C, a reaction time of 3 hours, 1:1 feed slurry dilution with 2M NaOH solution, the addition of CuSO{sub 4}.5H{sub 2}O solution (500 mg/L Cu) as catalyst, and the addition of 2000 mL/L of antifoam. However, for the destruction of TPB, its daughter compounds (3PB, 2PB, and 1PB), and phenol without consideration for biphenyl destruction, less severe conditions (280 C and 1-hour reaction time with similar remaining above conditions) are adequate.

  3. Preliminary toxicological study of Silastic 386 catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Smith, D.M.; Drake, G.A.; Holland, L.M.; Jackson, D.E.; London, J.E.; Prine, J.R.; Thomas, R.G.

    1978-06-01

    The calculated acute oral LD/sub 50//sup 30/ values for Silastic 386 catalyst were 1225 mg/kg in mice and 4350 mg/kg in rats. According to classical guidelines, the compound would be slightly to moderately toxic in both species. Skin application studies in the rabbit demonstrated the compound to be mildly irritating. The eye irritation study disclosed the compound to be a severe irritant causing conjunctivitis, photophobia, corneal edema, corneal ulceration, anterior uveitis, and keratitis. The sensitization study in the guinea pig did not show Silastic 386 catalyst to be deleterious in this regard.

  4. Demonstration of Small Tank Tetraphenylborate Precipitation Process Using Savannah River Site High Level Waste

    Energy Technology Data Exchange (ETDEWEB)

    Peters, T.B.

    2001-09-10

    This report details the experimental effort to demonstrate the continuous precipitation of cesium from Savannah River Site High Level Waste using sodium tetraphenylborate. In addition, the experiments examined the removal of strontium and various actinides through addition of monosodium titanate.

  5. Sexual selection studies: A NESCent catalyst meeting

    NARCIS (Netherlands)

    Roughgarden, J.; Adkins-Regan, E.; Akcay, E.; Hinde, C.A.; Hoquet, T.; O'Connor, C.; Prokop, Z.M.; Prum, R.O.; Shafir, S.; Snow, S.S.; Taylor, D.; Cleve, Van J.; Weisberg, M.

    2015-01-01

    A catalyst meeting on sexual selection studies was held in July 2013 at the facilities of the National Evolutionary Synthesis Center (NESCent) in Durham, NC. This article by a subcommittee of the participants foregrounds some of the topics discussed at the meeting. Topics mentioned here include the

  6. Theoretical studies of homogeneous catalysts mimicking nitrogenase.

    Science.gov (United States)

    Sgrignani, Jacopo; Franco, Duvan; Magistrato, Alessandra

    2011-01-10

    The conversion of molecular nitrogen to ammonia is a key biological and chemical process and represents one of the most challenging topics in chemistry and biology. In Nature the Mo-containing nitrogenase enzymes perform nitrogen 'fixation' via an iron molybdenum cofactor (FeMo-co) under ambient conditions. In contrast, industrially, the Haber-Bosch process reduces molecular nitrogen and hydrogen to ammonia with a heterogeneous iron catalyst under drastic conditions of temperature and pressure. This process accounts for the production of millions of tons of nitrogen compounds used for agricultural and industrial purposes, but the high temperature and pressure required result in a large energy loss, leading to several economic and environmental issues. During the last 40 years many attempts have been made to synthesize simple homogeneous catalysts that can activate dinitrogen under the same mild conditions of the nitrogenase enzymes. Several compounds, almost all containing transition metals, have been shown to bind and activate N₂ to various degrees. However, to date Mo(N₂)(HIPTN)₃N with (HIPTN)₃N= hexaisopropyl-terphenyl-triamidoamine is the only compound performing this process catalytically. In this review we describe how Density Functional Theory calculations have been of help in elucidating the reaction mechanisms of the inorganic compounds that activate or fix N₂. These studies provided important insights that rationalize and complement the experimental findings about the reaction mechanisms of known catalysts, predicting the reactivity of new potential catalysts and helping in tailoring new efficient catalytic compounds.

  7. Theoretical Studies of Homogeneous Catalysts Mimicking Nitrogenase

    Directory of Open Access Journals (Sweden)

    Alessandra Magistrato

    2011-01-01

    Full Text Available The conversion of molecular nitrogen to ammonia is a key biological and chemical process and represents one of the most challenging topics in chemistry and biology. In Nature the Mo-containing nitrogenase enzymes perform nitrogen ‘fixation’ via an iron molybdenum cofactor (FeMo-co under ambient conditions. In contrast, industrially, the Haber-Bosch process reduces molecular nitrogen and hydrogen to ammonia with a heterogeneous iron catalyst under drastic conditions of temperature and pressure. This process accounts for the production of millions of tons of nitrogen compounds used for agricultural and industrial purposes, but the high temperature and pressure required result in a large energy loss, leading to several economic and environmental issues. During the last 40 years many attempts have been made to synthesize simple homogeneous catalysts that can activate dinitrogen under the same mild conditions of the nitrogenase enzymes. Several compounds, almost all containing transition metals, have been shown to bind and activate N2 to various degrees. However, to date Mo(N2(HIPTN3N with (HIPTN3N= hexaisopropyl-terphenyl-triamidoamine is the only compound performing this process catalytically. In this review we describe how Density Functional Theory calculations have been of help in elucidating the reaction mechanisms of the inorganic compounds that activate or fix N2. These studies provided important insights that rationalize and complement the experimental findings about the reaction mechanisms of known catalysts, predicting the reactivity of new potential catalysts and helping in tailoring new efficient catalytic compounds.

  8. Study on MEA preparation with CoTETA/C catalysts as ORR catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Gan, T.; Zhang, H.J.; Jiang, Q.Z.; Ma, Z.F. [Shanghai Jiao Tong Univ., Shanghai (China). Dept. of Chemical Engineering

    2010-07-01

    Although carbon platinum is the most common cathode catalyst for proton exchange membrane fuel cells (PEMFCs) and zinc-air fuel cells, platinum is rare and costly. As such, there is a need to substitute platinum with a new and inexpensive catalyst for the oxygen reduction reaction (ORR). This paper presented a study in which a new non-platinum ORR catalysts was developed, notably the CoTETA/C. Although it demonstrated good performance, it had lower current density. Because of the conductivity and surface wetting properties of CoTETA/C, there was a poor contact between the catalyst layer and membrane of the membrane electrode assembly (MEA) prepared by the traditional method, which resulted in higher contact resistance and lower current density. The study showed that the performance of a single cell can be improved by adjusting the ratio of Nafion and catalyst in ink and adding a specified amount of additives to the ink. 1 ref.

  9. 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

  10. Fundamental studies of supported bimetallic catalysts by NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Savargaonkar, Nilesh [Iowa State Univ., Ames, IA (United States)

    1996-10-17

    Various hydrogenation reactions on transition metals are important commercially whereas certain hydrogenolysis reactions are useful from fundamental point of view. Understanding the hydrogen mobility and kinetics of adsorption-desorption of hydrogen is important in understanding the mechanisms of such reactions involving hydrogen. The kinetics of hydrogen chemisorption was studied by means of selective excitation NMR on silica supported Pt, Rh and Pt-Rh catalysts. The activation energy of hydrogen desorption was found to be lower on silica supported Pt catalysts as compared to Rh and Pt-Rh catalysts. It was found that the rates of hydrogen adsorption and desorption on Pt-Rh catalyst were similar to those on Rh catalyst and much higher as compared to Pt catalyst. The Ru-Ag bimetallic system is much simpler to study than the Pt-Rh system and serves as a model system to characterize more complicated systems such as the K/Ru system. Ag was found to decrease the amounts of adsorbed hydrogen and the hydrogen-to-ruthenium stoichiometry. Ag reduced the populations of states with low and intermediate binding energies of hydrogen on silica supported Ru catalyst. The rates of hydrogen adsorption and desorption were also lower on silica supported Ru-Ag catalyst as compared to Ru catalyst. This report contains introductory information, the literature review, general conclusions, and four appendices. An additional four chapters and one appendix have been processed separately for inclusion on the data base.

  11. Sodium tetraphenylborate solution stability: A long term study

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, M.J.

    1992-06-11

    Sodium tetraphenylborata (NaTPB) is a specialty chemical required for the In Tank Precipitation Process (ITP). It precipitates cesium, aiding in the decontamination of high level radioactive waste solutions. Long term stability of aqueous alkaline solutions of NATPB has been investigated. The focus of the investigation is on the relative stabilities of NATPB solutions exposed to varying temperatures and copper concentrations over an extended period of time. Additionally, vendor-supplied samples, incubated at 40{degree}C, were stored for more than a year without decomposing. Collected data demonstrates that in the absence of elevated copper concentrations, NATPB solutions will remain stable for periods of 1 to 2 years (at a minimum) at maximum expected operating conditions (<40{degree}C). Additionally, biuret, (H{sub 2}NCO){sub 2}NH, was tested as an additive to prevent copper-induced decomposition without success.

  12. Sodium tetraphenylborate solution stability: A long term study

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, M.J.

    1992-06-11

    Sodium tetraphenylborata (NaTPB) is a specialty chemical required for the In Tank Precipitation Process (ITP). It precipitates cesium, aiding in the decontamination of high level radioactive waste solutions. Long term stability of aqueous alkaline solutions of NATPB has been investigated. The focus of the investigation is on the relative stabilities of NATPB solutions exposed to varying temperatures and copper concentrations over an extended period of time. Additionally, vendor-supplied samples, incubated at 40[degree]C, were stored for more than a year without decomposing. Collected data demonstrates that in the absence of elevated copper concentrations, NATPB solutions will remain stable for periods of 1 to 2 years (at a minimum) at maximum expected operating conditions (<40[degree]C). Additionally, biuret, (H[sub 2]NCO)[sub 2]NH, was tested as an additive to prevent copper-induced decomposition without success.

  13. Studies of Deactivation of Methanol to Formaldehyde Selective Oxidation Catalyst

    DEFF Research Database (Denmark)

    Raun, Kristian Viegaard; Schumann, Max; Høj, Martin

    This work presents a study of the deactivation behavior of Fe-Mo oxide catalyst during selective oxidation of methanol to formaldehyde in a period of 5 days. The structural changes in the catalyst have been investigated in situ for the initial 10 h by Raman spectroscopy, and the structure after 5...

  14. Oxidation Catalyst Studies on a Diesel Engine

    OpenAIRE

    Ye, Shifei

    2010-01-01

    In this thesis, the experimental test facilities consisted of a well instrumented live Ford 2.0 litre turbocharged diesel engine connected to a specially made exhaust can, which contained a diesel oxidation catalyst (DOC). Experiments were performed on DOCs, which were specially prepared by Johnson Matthey, and had thermocouples mounted in their walls to measure axial temperature profiles. These DOCs consisted of a Pt catalyst dispersed in an alumina washcoat on a cordierite monolith supports...

  15. Isolation and stable nitrogen isotope analysis of ammonium ions in ammonium nitrate prills using sodium tetraphenylborate.

    Science.gov (United States)

    Howa, John D; Lott, Michael J; Ehleringer, James R

    2014-07-15

    Because of the threat of bombings using improvised explosives containing ammonium nitrate (AN), law enforcement and intelligence communities have been interested in stable isotope techniques for tracking and discriminating AN sources. Separate analysis of the AN component ions ammonium and nitrate would add discriminatory power to these techniques. Ammonium ions in dissolved AN solution were isolated from samples by precipitation using sodium tetraphenylborate solution. We tested the isolation of ammonium from nitrates using solutions of ammonium and nitrate salts with different (15)N/(14)N isotope ratios. Ammonium tetraphenylborate and AN were separately analyzed for their (15)N/(14)N isotope ratios using EA-ConFlo-IRMS, and the (15)N/(14)N isotope ratios of the nitrate ions were calculated using mass balance. Ammonium and nitrate nitrogen isotope ratios were plotted as two separate variables. Isolation of ammonium precipitate from solutions containing dissolved nitrates did not influence the nitrogen isotope ratios of test ammonium salts. A survey set of 42 AN samples showed that the ammonium and nitrate (15)N/(14)N isotope ratios were not significantly correlated, and the paired mean differences were not statistically significant. Both ammonium and nitrate were depleted in (15)N relative to their theoretical atmospheric sources. Isolation of the ammonium ion from AN adds another dimension for the discrimination of forensic AN samples. This technique using sodium tetraphenylborate is robust and does not require specialized equipment. Our observations indicated that ammonium nitrogen and nitrate nitrogen have independent sources of isotopic variation. Copyright © 2014 John Wiley & Sons, Ltd.

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

    Directory of Open Access Journals (Sweden)

    Mikkola J.-P.

    2003-01-01

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

  17. A study of platinum-supported catalysts through hyperfine interactions

    Science.gov (United States)

    Saitovitch, H.; Silva, P. R. J.; Rodriguez, A. M.; Weberszpil, J.; Passos, F. B.; Schmal, M.

    1994-12-01

    The effect of indium addition on alumina-supported platinum catalysts was investigated by measurements of hyperfine interactions. Via lime differential perturbed angular correlation spectroscopy (TDPAC) on111Cd, Pt/Al2O3 catalysts were studied in the flow of a heptane/H2 gas stream. The results indicate that some amount of indium sticks to platinum which is then dispersed on the support surface. The amount of In that is free from platinum is mobile under reaction conditions, being capable of diluting platinum particles and draining off coke precursors from the platinum surface.

  18. A study of platinum-supported catalysts through hyperfine interactions

    Energy Technology Data Exchange (ETDEWEB)

    Saitovitch, H. (Centro Brasileiro de Pesquisas Fisicas (CBPF/CNPq), Rio de Janeiro, RJ (Brazil)); Silva, P.R.J. (Centro Brasileiro de Pesquisas Fisicas (CBPF/CNPq), Rio de Janeiro, RJ (Brazil)); Rodriguez, A.M. (Centro Brasileiro de Pesquisas Fisicas (CBPF/CNPq), Rio de Janeiro, RJ (Brazil)); Weberszpil, J. (Centro Brasileiro de Pesquisas Fisicas (CBPF/CNPq), Rio de Janeiro, RJ (Brazil)); Passos, F.B. (Dept. Eng. Quimica, Univ. Fed. Fluminense, Niteroi, RJ (Brazil)); Schmal, M. (COPPE/EQ, Univ. Fed. Rio de Janeiro, RJ (Brazil))

    1994-05-01

    The effect of indium addition on alumina-supported platinum catalysts was investigated by measurements of hyperfine interactions. Via time differential perturbed angular correlation spectroscopy (TDPAC) on [sup 111]Cd, Pt/Al[sub 2]O[sub 3] catalysts were studied in the flow of a heptane/H[sub 2] gas stream. The results indicate that some amount of indium sticks to platinum which is then dispersed on the support surface. The amount of In that is free from platinum is mobile under reaction conditions, being capable of diluting platinum particles and draining off coke precursors from the platinum surface. (orig.)

  19. CO methanation over supported bimetallic Ni-Fe catalysts: From computational studies towards catalyst optimization

    DEFF Research Database (Denmark)

    Kustov, Arkadii; Frey, Anne Mette; Larsen, Kasper Emil

    2007-01-01

    200-300 degrees C, and characterized using elemental analysis, N-2 physisorption measurements, XRD and TEM. Optimization of the catalyst performance was made by varying the Ni:Fe ratio, the total metal loading and the support material. For both support materials, the bimetallic catalysts...

  20. Studies of Immobilized Homogeneous Metal Catalysts on Silica Supports

    Energy Technology Data Exchange (ETDEWEB)

    Stanger, Keith James [Iowa State Univ., Ames, IA (United States)

    2003-01-01

    The tethered, chiral, chelating diphosphine rhodium complex, which catalyzes the enantioselective hydrogenation of methyl-α-acetamidocinnamate (MAC), has the illustrated structure as established by 31P NMR and IR studies. Spectral and catalytic investigations also suggest that the mechanism of action of the tethered complex is the same as that of the untethered complex in solution. The rhodium complexes, [Rh(COD)H]4, [Rh(COD)2]+BF4-, [Rh(COD)Cl]2, and RhCl3• 3H2O, adsorbed on SiO2 are optimally activated for toluene hydrogenation by pretreatment with H2 at 200 C. The same complexes on Pd-SiO2 are equally active without pretreatments. The active species in all cases is rhodium metal. The catalysts were characterized by XPS, TEM, DRIFTS, and mercury poisoning experiments. Rhodium on silica catalyzes the hydrogenation of fluorobenzene to produce predominantly fluorocyclohexane in heptane and 1,2-dichloroethane solvents. In heptane/methanol and heptane/water solvents, hydrodefluorination to benzene and subsequent hydrogenation to cyclohexane occurs exclusively. Benzene inhibits the hydrodefluorination of fluorobenzene. In DCE or heptane solvents, fluorocyclohexane reacts with hydrogen fluoride to form cyclohexene. Reaction conditions can be chosen to selectively yield fluorocyclohexane, cyclohexene, benzene, or cyclohexane. The oxorhenium(V) dithiolate catalyst [-S(CH2)3s-]Re(O)(Me)(PPh3) was modified by linking it to a tether that could be attached to a silica support. Spectroscopic investigation and catalytic oxidation reactivity showed the heterogenized catalyst's structure and reactivity to be similar to its homogeneous analog. However, the immobilized catalyst offered additional advantages of recyclability, extended stability, and increased resistance to deactivation.

  1. 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.

  2. Study of superhydrophobic electrosprayed catalyst layers using a localized reference electrode technique

    Science.gov (United States)

    Chaparro, A. M.; Ferreira-Aparicio, P.; Folgado, M. A.; Brightman, E.; Hinds, G.

    2016-09-01

    The performance of electrosprayed cathode catalyst layers in a polymer electrolyte membrane fuel cell (PEMFC) is studied using a localized reference electrode technique. Single cells with an electrosprayed cathode catalyst layer show an increase of >20% in maximum power density under standard testing conditions, compared with identical cells assembled with a conventional, state-of-the-art, gas diffusion cathode. When operated at high current density (1.2 A cm-2) the electrosprayed catalyst layers show more homogeneous distribution of the localized cathode potential, with a standard deviation from inlet to outlet of gas diffusion cathode. Higher performance and homogeneity of cell response is attributed to the superhydrophobic nature of the macroporous electrosprayed catalyst layer structure, which enhances the rate of expulsion of liquid water from the cathode. On the other hand, at low current densities (catalyst layers. The optimum performance may be obtained with electrosprayed catalyst layers employing a high Pt/C catalyst ratio.

  3. 2-Dimethylamino-1-(2-ethoxy-2-oxoethyl-3-methyl-4,5-dihydroimidazolium tetraphenylborate

    Directory of Open Access Journals (Sweden)

    Ioannis Tiritiris

    2016-01-01

    Full Text Available In the crystal structure of the title salt, C10H20N3O2+·C24H20B−, the C—N bond lengths in the cation are 1.327 (3, 1.339 (3 and 1.342 (3 Å, indicating partial double-bond character. The central C atom is bonded to the three N atoms, indicating only a slight deviation from a trigonal–planar geometry. The positive charge is delocalized in the CN3 plane. The ethoxy group is disordered over two orientations, with an occupancy ratio of 0.60 (1:0.40 (1. C—H...π interactions are present between the guanidinium H atoms and the phenyl C atoms of the tetraphenylborate ions. The phenyl rings form aromatic pockets, in which the cations are embedded. This leads to the formation of a two-dimensional supramolecular pattern along the ac plane.

  4. Catalyst Schools' Implementation of the Learning School Approach. Catalyst Schools Research Study Report

    Science.gov (United States)

    Hammer, Patricia Cahape

    2016-01-01

    "Catalyst schools" were 28 elementary and secondary schools selected to participate in a pilot project begun in July 2014, which explored how best to support teacher professional learning through decentralization of decision making and implementation of the Learning School approach. The pilot project was the first phase in a statewide…

  5. Derivative spectrophotometric determination of trace lead in alloys and biological samples after separation and preconcentration with the ion pair of 2-(5-bromo-2-pyridylazo-5-diethylaminophenol and ammonium tetraphenylborate on microcrystalline naphthalene or by column method

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Taher

    2003-12-01

    Full Text Available Lead is quantitatively retained on 2-(5-bromo-2-pyridylazo-5-diethylaminophenol-ammonium tetraphenylborate with microcrystalline naphthalene or by a column method in the pH range 4.0–6.0 from a large volume of aqueous solutions of various samples. After filtration, the solid mass consisting of the lead complex and naphthalene was dissolved with 5 mL of dimethylformamide and the metal was determined by third derivative spectrophotometry. Lead complex can alternatively be quantitatively adsorbed on ammonium tetraphenylborate-naphthalene adsorbent packed in a column and determined similarly. About 0.2 μg of lead can be concentrated in a column from 300 mL of aqueous sample, where its concentration is as low as 0.7 ng/mL. The interference of a large number of anions and cations has been studied and the optimized conditions developed have been utilized for the trace determination of lead in various samples.

  6. Study of microstructure and water transport properties in catalyst layers of polymer electrolyte fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Soboleva, T.; Eikerling, M.; Holdcroft, S. [Simon Fraser Univ., Burnaby, BC (Canada). Dept. of Chemistry; Malek, K.; Navessin, T. [National Research Council of Canada, Vancouver, BC (Canada). Inst. for Fuel Cell Innovation

    2009-07-01

    This study investigated the influence of Nafion ionomer content and carbon supports on the microstructure and water vapour sorption characteristics of proton exchange membrane fuel cell (PEMFC) catalyst layers. The catalyst layers were spray-coated onto Nafion 211 membranes. Nitrogen adsorption techniques were used to analyze pore size distribution and microstructure. The study examined nitrogen sorption isotherms and sorption hysteresis in relation to pore shape and pore networks. A model was used to determine pore connectivity and other topological parameters. Dynamic vapour sorption measurements were used to study the sorption characteristics of the catalyst coated membranes (CCMs). It was concluded that sorption behaviour is influenced by different components within the catalyst layer.

  7. ETEM Studies of Electrodes and Electro-catalysts

    DEFF Research Database (Denmark)

    Jooss, Christian; Mildner, Stephanie; Beleggia, Marco

    2016-01-01

    sample holders. To illustrate how this can be achieved, we present the results of a bias-controlled electro-corrosion experiment. We will discuss some of the main experimental and theoretical challenges for the development of controlled electrochemistry studies in transmission electron microscopes......./oxygen evolution and electrochemical corrosion processes of materials have been studied in some pioneering experiments which will be summarized in this chapter. These experiments often reveal a strong change of the electrode due to the adsorption of gas species from the environment as well as due to the impact...... of the electron beam. We show that inelastic scattering of the high-energy electrons can induce electric potentials in the studied samples influencing the observed state of the catalyst. After an introduction to electrochemistry and ETEM investigations, we address, experimentally and theoretically, beam...

  8. Autothermal reforming of JP8 on a Pt/Rh catalyst: Catalyst durability studies and effects of sulfur

    Science.gov (United States)

    Klinghoffer, Naomi B.; Barrai, Federico; Castaldi, Marco J.

    2011-08-01

    Autothermal reforming (ATR) of commercial grade JP8 was performed on a Pt/Rh catalyst deposited on a monolith. This study investigated catalyst performance under three test conditions: (i) 120 startup and shutdown cycles, (ii) 80 h of continuous operation with sulfur-free fuel, and (iii) 370 h of testing with JP8 containing 125 ppm of sulfur. Axial reactor temperature profiles and gas composition data showed that startup and shutdown cycling had no impact on catalyst performance. When durability testing was done with fuel containing 125 ppm of sulfur, the catalyst deactivated initially, which was reflected by a decrease in H2 concentration and decrease in fuel conversion. However, after 250 h of operation the activity stabilized at 66% fuel conversion and product concentrations were constant for the remaining 120 h of testing. The presence of sulfur resulted in higher CO selectivity, lower H2 concentrations, and lower fuel conversions compared to data with sulfur-free fuel. The data suggests that the presence of sulfur primarily affects steam reforming reactions, and CO oxidation. Regeneration was attempted with air and with fuel-lean combustion but initial H2 yields and carbon selectivity were not achieved.

  9. Adsorption, Diffusion and Reaction Studies of Hydrocarbons on Zeolite Catalysts

    NARCIS (Netherlands)

    Donk, Sander van

    2002-01-01

    Zeolites are crystalline microporous materials that are widely applied as catalysts in industries like oil refining, basic petrochemistry and fine chemistry. The major benefit of the use of zeolites as catalysts lies in their unique microporous structures. However, in some cases the presence of

  10. The asymmetric Schrock olefin metathesis catalysts. A computational study

    NARCIS (Netherlands)

    Goumans, T.P.M.; Ehlers, A.W.; Lammertsma, K.

    2005-01-01

    The mechanism of the transition metal catalyzed olefin metathesis reaction with the Schrock catalyst is investigated with pure (BP86) and hybrid (B3LYP) density functional theory. On the free-energy surface there is no adduct between ethylene and model catalyst (MeO)

  11. Study on Endurance and Performance of Impregnated Ruthenium Catalyst for Thruster System.

    Science.gov (United States)

    Kim, Jincheol; Kim, Taegyu

    2018-02-01

    Performance and endurance of the Ru catalyst were studied for nitrous oxide monopropellant thruster system. The thermal decomposition of N2O requires a considerably high temperature, which make it difficult to be utilized as a thruster propellant, while the propellant decomposition temperature can be reduced by using the catalyst through the decomposition reaction with the propellant. However, the catalyst used for the thruster was frequently exposed to high temperature and high-pressure environment. Therefore, the state change of the catalyst according to the thruster operation was analyzed. Characterization of catalyst used in the operation condition of the thruster was performed using FE-SEM and EDS. As a result, performance degradation was occurred due to the volatilization of Ru catalyst and reduction of the specific surface area according to the phase change of Al2O3.

  12. Studies on PEM fuel cell noble metal catalyst dissolution

    DEFF Research Database (Denmark)

    Andersen, S. M.; Grahl-Madsen, L.; Skou, E. M.

    2011-01-01

    A combination of electrochemical, spectroscopic and gravimetric methods was carried out on Proton Exchange Membrane (PEM) fuel cell electrodes with the focus on platinum and ruthenium catalysts dissolution, and the membrane degradation. In cyclic voltammetry (CV) experiments, the noble metals were...... found to dissolve in 1 M sulfuric acid solution and the dissolution increased exponentially with the upper potential limit (UPL) between 0.6 and 1.6 vs. RHE. 2-20% of the Pt (depending on the catalyst type) was found to be dissolved during the experiments. Under the same conditions, 30-100% of the Ru...... (depending on the catalyst type) was found to be dissolved. The faster dissolution of ruthenium compared to platinum in the alloy type catalysts was also confirmed by X-ray diffraction measurements. The dissolution of the carbon supported catalyst was found one order of magnitude higher than the unsupported...

  13. TASK TECHNICAL AND QUALITY ASSURANCE PLAN FOR OUT-OF-TANK DESTRUCTION OF TETRAPHENYLBORATE VIA WET AIR OXIDATION TECHNOLOGY: PHASE I - BENCH SCALE TESTS

    Energy Technology Data Exchange (ETDEWEB)

    Adu-Wusu, K

    2006-03-31

    Tank 48H return to service is critical to the processing of high level waste (HLW) at Savannah River Site (SRS). Liquid Waste Disposition (LWD) management has the goal of returning Tank 48H to routine service by January 2010 or as soon as practical. Tank 48H currently holds legacy material containing organic tetraphenylborate (TPB) compounds from the operation of the In-Tank Precipitation process. This material is not compatible with the waste treatment facilities at SRS and must be removed or undergo treatment to destroy the organic compounds before the tank can be returned to Tank Farm service. Tank 48H currently contains {approx}240,000 gallons of alkaline slurry with about 2 wt % potassium and cesium tetraphenylborate (KTPB and CsTPB). The main radioactive component in Tank 48H is {sup 137}Cs. The waste also contains {approx}0.15 wt % Monosodium Titanate (MST) which has adsorbed {sup 90}Sr, U, and Pu isotopes. A System Engineering Evaluation of technologies/ideas for the treatment of TPB identified Wet Air Oxidation (WAO) as a leading alternative technology to the baseline aggregation approach. Over 75 technologies/ideas were evaluated overall. Forty-one technologies/ideas passed the initial screening evaluation. The 41 technologies/ideas were then combined to 16 complete solutions for the disposition of TPB and evaluated in detail. Wet Air Oxidation (WAO) is an aqueous phase process in which soluble or suspended waste components are oxidized using molecular oxygen contained in air. The process operates at elevated temperatures and pressures ranging from 150 to 320 C and 7 to 210 atmospheres, respectively. The products of the reaction are CO{sub 2}, H{sub 2}O, and low molecular weight oxygenated organics (e.g. acetate, oxalate). The basic flow scheme for a typical WAO system is as follows. The waste solution or slurry is pumped through a high-pressure feed pump. An air stream containing sufficient oxygen to meet the oxygen requirements of the waste stream is

  14. XAS study of vanadium in fluid cracking catalysts

    Science.gov (United States)

    Woolery, G. L.; Chin, A. A.; Kirker, G. W.; Huss, A.

    1989-06-01

    X-ray absorption spectroscopy was used to investigate the oxidation state and local environment of vanadium in Fluid Catalytic Cracking (FCC) catalysts as a function of processing and deactivation conditions. Our results suggest that oxidation of vanadium to V+5 alone is not solely responsible for catalyst deactivation but that other factors such as vanadium location and mobility play a significant role in catalyst performance. Basic alkaline earth oxide passivators such as MgO were found to interact strongly with vanadium during the regeneration period leading to formation of a magnesium vanadate compound.

  15. Supporting Statewide Implementation of the Learning School Initiative. Catalyst Schools Research Study Report

    Science.gov (United States)

    Hammer, Patricia Cahape

    2016-01-01

    This is the first in a series of reports based on a research study, Developing Effective Professional Learning Communities in Catalyst Schools, conducted between February 2015 and June 2016. "Catalyst schools" were elementary- and secondary-level schools selected to participate in a pilot project intended to explore how best to support…

  16. N,N,N′,N′-Tetramethyl-N′′-[2-(trimethylazaniumylethyl]guanidinium bis(tetraphenylborate acetone disolvate

    Directory of Open Access Journals (Sweden)

    Ioannis Tiritiris

    2016-02-01

    Full Text Available The asymmetric unit of the title solvated salt, C10H26N42+·2C24H20B−·2C3H6O, comprises one cation, two tetraphenylborate ions and two acetone solvent molecules. The N and methyl C atoms of the terminal trimethylammonium group are disordered over two sets of sites, with a refined occupancy ratio of 0.846 (3:0.154 (3. The C—N bond lengths in the central C3N unit of the guanidinium ion range between 1.3308 (16 and 1.3508 (16 Å, indicating a degree of double-bond character. The central C atom is bonded to the three N atoms in a nearly ideal trigonal–planar geometry and the positive charge is delocalized in the CN3 plane. The C—N bond lengths in the terminal trimethylammonium group have values close to that of a typical single bond, and the second positive charge is localized there. In the crystal, the guanidinium ion is connected by N—H...O and C—H...O hydrogen bonds with the acetone molecules. C—H...π interactions are present between the guanidinium H atoms and the phenyl rings of the tetraphenylborate ions, leading to the formation of a two-dimensional supramolecular pattern along the bc plane.

  17. Study on novel and promising NH3-SCR catalysts on glass fiber cloth for industrial applications

    Science.gov (United States)

    Xie, Junlin; Li, Fengxiang; Hu, Hua; Qi, Kai; He, Feng; Fang, De

    2017-05-01

    MnO x , Mn/TiO2 and Fe-Mn/TiO2 catalysts were prepared by precipitation-impregnation method. The MnO x catalyst shows the highest activity for the reduction of NO with NH3 at the temperature range of 80 °C to 140 °C, and achieves more than 98% of NO conversion at 140 °C. The MnO x catalyst loaded on glass fiber cloth (GFC) was prepared by impregnation method, and the effects of preparation conditions were studied. It turns out that the catalyst particle size, loading capacity and catalyst varieties make a great difference to catalytic performance. In addition, the catalyst with aluminum sol as a binder has the higher catalytic activity but poor ability of anti-sulfur and anti-water poisoning, compared with the catalyst using silica sol binder. Further, MnO x , Mn/TiO2 and Fe-Mn/TiO2 powders were loaded onto GFC using XRD, HRTEM, TGA, SEM, BET, H2-TPR and NH3-TPD to systematically characterize the various physico-chemical properties and denitrition activity. The results indicate that the changes of active components, specific surface area, microstructure, reducibility and suface acidity of the three kinds of catalysts lead to different catalytic activities.

  18. STUDY OF SOLVENT AND CATALYST INTERACTIONS IN DIRECT COAL LIQUEFACTION

    Energy Technology Data Exchange (ETDEWEB)

    Michael T. Klein

    2000-01-01

    There are several aspects of the Direct Coal Liquefaction process which are not fully understood and which if better understood might lead to improved yields and conversions. Among these questions are the roles of the catalyst and the solvent. While the solvent is known to act by transfer of hydrogen atoms to the free radicals formed by thermal breakdown of the coal in an uncatalyzed system, in the presence of a solid catalyst as is now currently practiced, the yields and conversions are higher than in an uncatalyzed system. The role of the catalyst in this case is not completely understood. DOE has funded many projects to produce ultrafine and more active catalysts in the expectation that better contact between catalyst and coal might result. This approach has met with limited success probably because mass transfer between two solids in a fluid medium i.e. the catalyst and the coal, is very poor. It is to develop an understanding of the role of the catalyst and solvent in Direct Liquefaction that this project was initiated. Specifically it was of interest to know whether direct contact between the coal and the catalyst was important. By separating the solid catalyst in a stainless steel basket permeable to the solvent but not the coal in the liquefaction reactor, it was shown that the catalyst still maintains a catalytic effect on the liquefaction process. There is apparently transfer of hydrogen atoms from the catalyst through the basket wall to the coal via the solvent. Strong hydrogen donor solvents appear to be more effective in this respect than weak hydrogen donors. It therefore appears that intimate contact between catalyst and coal is not a requirement, and that the role of the catalyst may be to restore the hydrogen donor strength to the solvent as the reaction proceeds. A range of solvents of varying hydrogen donor strength was investigated. Because of the extensive use of thermogravimetric analysis in this laboratory in was noted that the peak

  19. STUDY OF SOLVENT AND CATALYST INTERACTIONS IN DIRECT COAL LIQUEFACTION

    Energy Technology Data Exchange (ETDEWEB)

    Michael T. Klein

    2000-01-01

    Using a reactor in which the coal is physically separated from the solid catalyst by a porous wall permeable to the hydrogen donor solvent, it was shown that direct contact between the catalyst and the coal is not required for catalyzed coal liquefaction. This occurs however only when there is a hydrogen atmosphere, as liquefaction with catalyst participation does not occur in a nitrogen atmosphere. Liquefaction by hydrogen transfer from the donor solvent itself does occur. This suggests that there is transfer of hydrogen from the catalyst to the coal via the solvent. The character of the solvent makes a significant difference, the better solvents being good hydrogen donors. These results indicate that the role of the catalyst may be to regenerate the spent hydrogen donor solvent during the liquefaction process. The peak temperature for volatiles evolution has been shown to be a reproducible measure of the coal rank. This was shown by an excellent correlation (R2 = 0.998) between peak volatiles temperatures (by TGA) and vitrinite reflectance. Using TG/MS, the volatiles contents of coals of a wide range of ranks was determined. The low rank coals emit largely phenols and some other oxygen compounds and olefins. The higher rank coals emit largely aromatic hydrocarbons and some olefins.

  20. Facile and One Pot Synthesis of Gold Nanoparticles Using Tetraphenylborate and Polyvinylpyrrolidone for Selective Colorimetric Detection of Mercury Ions in Aqueous Medium

    Directory of Open Access Journals (Sweden)

    Sidhureddy Boopathi

    2012-01-01

    Full Text Available In this work, we reported for the first time, a facile and one step synthesis of gold nanoparticles from HAuCl4, employing tetraphenylborate as the reducing agent. The synthesis is not only facile but also yields “dumb-bell-shaped”particles. This shape appears to arise from a possible emulsion of the products of oxidation/decomposition of tetraphenylborate by HAuCl4, surrounding the particle. The size and shape of the AuNPs were characterized by Transmission electron microscopy (TEM and UV-visible Spectroscopy. Interestingly, the addition of polyvinylpyrrolidone (PVP during the synthesis was found to enhance the stability of the nanoparticle dispersion. The particles synthesized under these conditions assume “spherical” shape with the appearance of only transverse surface plasmon resonance band. The highlight of the observations is that the gold nanoparticles synthesized using tetraphenylborate as reducing agent and PVP as stabilizer are highly stable in alkaline medium, in contrast to the synthesis wherein borohydride is used as reducing agent. The AuNPs synthesized using tetraphenylborate and PVP show their mercury sensing behavior only in the alkaline medium. The color of the nanoparticle dispersion undergoes distinct color change from pink to blue with the addition of mercury ions. They also show dramatic selectivity to mercury ions in presence of other interfering ions, Pb2+, Zn2+ and Ca2+.

  1. Studies of Deactivation of Methanol to Formaldehyde Selective Oxidation Catalyst

    DEFF Research Database (Denmark)

    Raun, Kristian Viegaard; Schumann, Max; Høj, Martin

    Formaldehyde (CH2O) may be synthesized industrially by selective oxidation of methanol over an iron-molybdate (Fe-Mo) oxide catalyst according to: CH3OH + ½O2 →CH2O + H2O. The reaction is normally carried out in a multitubular reactor with excess of air at 250-400 °C (yield = 90-95 %), known...... as the Formox process [1]. The average lifetime of the industrial catalyst is only 1–2 years depending on the operating conditions. The catalyst consists of a bulk phase of Fe2(MoO4)3 and a surface layer phase of MoO3. The MoO3 surfaceis selective towards formaldehyde while the iron in the sublayer increases...

  2. Studies on PEM Fuel Cell Noble Metal Catalyst Dissolution

    DEFF Research Database (Denmark)

    Ma, Shuang; Skou, Eivind Morten

    Incredibly vast advance has been achieved in fuel cell technology regarding to catalyst efficiency, improvement of electrolyte conductivity and optimization of cell system. With breathtakingly accelerating progress, Proton Exchange Membrane Fuel Cells (PEMFC) is the most promising and most widely....... Membrane Electrode Assembly (MEA) is commonly considered as the heart of cell system [2]. Degradation of the noble metal catalysts in MEAs especially Three-Phase-Boundary (TPB) is a key factor directly influencing fuel cell durability. In this work, electrochemical degradation of Pt and Pt/Ru alloy were...

  3. MAGNETO-CHEMICAL CHARACTER STUDIES OF NOVEL Fe CATALYSTS FOR COAL LIQUEFACTION

    Energy Technology Data Exchange (ETDEWEB)

    Murty A. Akundi; Jian H. Zhang; A.N. Murty; S.V. Naidu

    2002-04-01

    The objectives of the present study are: (1) To synthesize iron catalysts: Fe/MoO{sub 3}, and Fe/Co/MoO{sub 3} employing two distinct techniques: Pyrolysis with organic precursors and Co-precipitation of metal nitrates; (2) To investigate the magnetic character of the catalysts before and after exposure to CO and CO+H{sub 2} by (a) Mossbauer study of Iron (b) Zerofield Nuclear Magnetic Resonance study of Cobalt, and (c) Magnetic character of the catalyst composite; (3) To study the IR active surface species of the catalyst while stimulating (CO--Metal, (CO+H{sub 2})--Metal) interactions, by FTIR Spectroscopy; and (4) To analyze the catalytic character (conversion efficiency and product distribution) in both direct and indirect liquefaction Process and (5) To examine the correlations between the magnetic and chemical characteristics. This report presents the results of our investigation on (a) the effect of metal loading (b) the effect of intermetallic ratio and (c) the effect of catalyst preparation procedure on (i) the magnetic character of the catalyst composite (ii) the IR active surface species of the catalyst and (iii) the catalytic yields for three different metal loadings: 5%, 15%, and 25% (nominal) for three distinct intermetallic ratios (Fe/Co = 0.3, 1.5, 3.0).

  4. 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

  5. Studies of supported metal catalysts. Progress report, September 1, 1980-August 31, 1981

    Energy Technology Data Exchange (ETDEWEB)

    Hercules, D.M.

    1981-04-01

    During this period research has been carried out on five separate catalyst systems. The effect of zinc ions on the interaction between cobalt and ..gamma..-Al/sub 2/O/sub 3/ has been studied. Work on the oxidic Mo/Al/sub 2/O/sub 3/ system has been published and studies have been extended to the sulfided catalysts. The first phase of work on the Co/Mo/Al/sub 2/O/sub 3/ system has been completed. Work on W/Al/sub 2/O/sub 3/ catalysts has begun and the oxidic system has been studied in some detail. Work continues on metal-support interactions in supported nickel catalysts. An electron spectroscopy (ESCA) study has been completed and work is continuing on correlation of the ESCA results with measurements like temperature programmed desorption (TPD) and temperature programmed reduction (TPRd).

  6. 2-Dimethylamino-1-(2-ethoxy-2-oxoethyl-3-methyl-3,4,5,6-tetrahydropyrimidin-1-ium tetraphenylborate

    Directory of Open Access Journals (Sweden)

    Ioannis Tiritiris

    2012-07-01

    Full Text Available Isolated guanidinium ions and tetraphenylborate ions are present in the crystal structure of the title compound, C11H22N3O2+·C24H20B−. In the guanidinium ion, the dihedral angle between the N/C/N and C/C/C planes being 49.9 (1°. The six-membered ring exhibits a half-chair conformation. The C—N bond lengths in the cation range between 1.3335 (16 and 1.3552 (16 Å, indicating charge delocalization on the CN3 plane. In the crystal, the cations are connected by C—H...O hydrogen bonds, generating a chain along the c axis.

  7. Preparation of ractopamine-tetraphenylborate complexed nanoparticles used as sensors to rapidly determine ractopamine residues in pork

    Science.gov (United States)

    Zhang, Jing; Shao, Xintian; Yue, Jingli; Li, Donghui; Chen, Zhenhua

    2014-11-01

    In this work, we reported a simple, fast, and sensitive determination of ractopamine (RAC) residues in pork by using novel ractopamine-tetraphenylborate complexed nanoparticles (RT NPs) as sensors. The prepared RT NPs exhibited a fast response time of 10 s, a wide linear range from 0.1 to 1.0 × 10-7 mol/L, and a very low detection limit of 7.4 × 10-8 mol/L. The prepared sensor also presents a high selectivity for ractopamine under different pH conditions ranged from 2.85 to 7.18. These results reveal that the fabricated RT NPs can be used as efficient electrochemical sensors to determine ractopamine in animal productions.

  8. An optimization study of PtSn/C catalysts applied to direct ethanol fuel cell: Effect of the preparation method on the electrocatalytic activity of the catalysts

    Science.gov (United States)

    Almeida, T. S.; Palma, L. M.; Leonello, P. H.; Morais, C.; Kokoh, K. B.; De Andrade, A. R.

    2012-10-01

    The aim of this work was to perform a systematic study of the parameters that can influence the composition, morphology, and catalytic activity of PtSn/C nanoparticles and compare two different methods of nanocatalyst preparation, namely microwave-assisted heating (MW) and thermal decomposition of polymeric precursors (DPP). An investigation of the effects of the reducing and stabilizing agents on the catalytic activity and morphology of Pt75Sn25/C catalysts prepared by microwave-assisted heating was undertaken for optimization purposes. The effect of short-chain alcohols such as ethanol, ethylene glycol, and propylene glycol as reducing agents was evaluated, and the use of sodium acetate and citric acid as stabilizing agents for the MW procedure was examined. Catalysts obtained from propylene glycol displayed higher catalytic activity compared with catalysts prepared in ethylene glycol. Introduction of sodium acetate enhanced the catalytic activity, but this beneficial effect was observed until a critical acetate concentration was reached. Optimization of the MW synthesis allowed for the preparation of highly dispersed catalysts with average sizes lying between 2.0 and 5.0 nm. Comparison of the best catalyst prepared by MW with a catalyst of similar composition prepared by the polymeric precursors method showed that the catalytic activity of the material can be improved when a proper condition for catalyst preparation is achieved.

  9. Transient studies of low temperature catalysts for methane conversion. Final report, [September 1992--March 1996

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, E.E.

    1996-09-30

    The objective of this project is to use transient techniques to study gas surface interactions during the oxidative conversion of methane. Two groups of catalysts were studied: a double oxide of vanadium and phosphate or VPO, and double oxides of Ni, Co and Rh and lanthana. The objective of the studies involving the VPO catalyst was to understand gas-surface interactions leading to the formation of formaldehyde. In the second group of catalysts, involving metallo-oxides, the main objective was to study the gas-surface interactions that determine the selectivity to C{sub 2} hydrocarbons or synthesis gas. Transient techniques were used to study the methane-surface interactions and the role of lattice oxygen. The selection of the double oxides was made on the hypothesis that the metal oxide would provide an increase interaction with methane whereas the phosphate or lanthanide would provide the sites for oxygen adsorption. The hypothesis behind this selection of catalysts was that increasing the methane interaction with the catalysts would lower the reaction temperature and thus increase the selectivity to the desired products over the total oxidation reaction. In both groups of catalysts the role of Li as a modifier of the selectivity was also studied in detail.

  10. N,N,N′,N′,N′′-Pentamethyl-N′′-[2-(trimethylazaniumylethyl]guanidinium bis(tetraphenylborate acetone monosolvate

    Directory of Open Access Journals (Sweden)

    Ioannis Tiritiris

    2016-02-01

    Full Text Available The asymmetric unit of the title solvated salt, C11H28N42+·2C24H20B−·C3H6O, comprises two cations, four tetraphenylborate anions and two acetone molecules. One cation shows an orientational disorder at the CN3 moiety and two sets of N-atom positions were found related by a 60° rotation, with a refined occupancy ratio of 0.935 (1:0.065 (1. The respective nitrogen-bonded –CH2 and –CH3 groups are included in the disorder model. The C—N bond lengths in the central CN3 units of both guanidinium ions range between 1.3329 (17 and 1.364 (16 Å, indicating a degree of double-bond character. The central C atom is bonded to the three N atoms in a nearly ideal trigonal–planar geometry and one positive charge is delocalized in the CN3 plane. The C—N bond lengths in the terminal trimethylammonium groups have values close to a typical single bond, and the second positive charge is localized there. In the crystal, the guanidinium ions are connected by C—H...O hydrogen bonds with the acetone molecules. C—H...π interactions are present between the guanidinium and acetone hydrogen atoms and the phenyl rings of the tetraphenylborate ions, leading to the formation of a two-dimensional supramolecular pattern along the bc plane.

  11. Catalytic deactivation on methane steam reforming catalysts. 2. Kinetic study

    Energy Technology Data Exchange (ETDEWEB)

    Agnelli, M.E.; Ponzi, E.N.; Yeramian, A.A.

    1987-08-01

    The kinetics of methane steam reforming reaction over an alumina-supported nickel catalyst was investigated at a temperature range of 640-740/sup 0/C in a flow reactor at atmospheric pressure. The experiments were performed varying the inlet concentration of methane, hydrogen, and water. A kinetic scheme of the Houghen-Watson type was satisfactorily proposed assuming the dissociative adsorption of CH/sub 4/ as the rate-limiting step, but this kinetic scheme can be easily replaced by a first-order kinetics (r/sub CH/4/sub / = kapparho/sub CH/4/sub /) for engineering purposes. Catalyst activation with H/sub 2/ and N/sub 2/ mixtures or with the reactant mixture results in the same extent of reaction.

  12. Study of propane partial oxidation on vanadium-containing catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Komashko, G.A.; Khalamejda, S.V.; Zazhigalov, V.A. [AN Ukrainskoj SSR, Kiev (Ukraine). Inst. Fizicheskoj Khimii

    1998-12-31

    The present results indicate that maximum selectivity to acrylic acid can be reached over V-P-Zr-O catalysts. When the hydrocarbon concentration is 5.1 vol.% the selectivity is about 30% at quite high paraffin conversion. Conclusively, some explanations to the observed facts can be given. The V-P-O catalyst promotion with lanthanum by means of mechanochemical treatment is distinguished by the additive uniform spreading all over the matrix surface. Such twophase system is highly active in propane conversion (lanthanum oxide) and further oxidation of the desired products. The similar properties are attributed to V-P-Bi-La-O catalyst. Bismuth, tellurium and zirconium additives having clearly defined acidic properties provoke the surface acidity strengthening and make easier desorption of the acidic product (acrylic acid) from the surface lowering its further oxidation. Additionally, since bismuth and zirconium are able to form phosphates and, according to, to create space limitations for the paraffin molecule movement out of the active group boundaries, this can be one more support in favour of the selectivity increase. With this point of view very interesting results were obtained. It has been shown that the more limited the size of the vanadium unit, the higher the selectivity is. Monoclinic phase AV{sub 2}P{sub 2}O{sub 10} which consists in clusters of four vanadium atoms is sensibly more reactive than the orthorhombic phase consists in V{sub {infinity}} infinite chains. (orig.)

  13. Chemisorption studies of Pt/SnO2 catalysts

    Science.gov (United States)

    Brown, Kenneth G.; Ohorodnik, Susan K.; Vannorman, John D.; Schryer, Jacqueline; Upchurch, Billy T.; Schryer, David R.

    1990-01-01

    The low temperature CO oxidation catalysts that are being developed and tested at NASA-Langley are fairly unique in their ability to efficiently oxidize CO at low temperatures (approx. 303 K). The bulk of the reaction data that has been collected in the laboratory has been determined using plug flow reactors with a low mass of Pt/SnO2/SiO2 catalyst (approx. 0.1 g) and a modest flow rate (5 to 10 sc sm). The researchers have previously characterized the surface solely in terms of N2 BET surface areas. These surface areas have not been that indicative of reaction rate. Indeed, some of the formulations with high BET surface area have yielded lower reaction rates than those with lower BET surface areas. As a result researchers began a program of determining the chemisorption of the various species involved in the reaction; CO, O2 and CO2. Such a determination of will lead to a better understanding of the mechanism and overall kinetics of the reaction. The pulsed-reactor technique, initially described by Freel, is used to determine the amount of a particular molecule that is adsorbed on the catalyst. Since there is some reaction of CO with the surface to produce CO2, the pulsed reactor had to be coupled with a gas chromatograph in order to distinguish between the loss of CO that is due to adsorption by the surface and the loss that is due to reaction with the surface.

  14. Further studies on hydration of alkynes by the PtCl4-CO catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Israelsohn, Osnat; Vollhardt, K. Peter C.; Blum, Jochanan

    2002-01-18

    Under CO atmosphere, between 80 and 120 C, a glyme solution of PtCl{sub 4} forms a carbonyl compound that promotes hydration of internal as well as terminal alkynes to give aldehyde-free ketones. The catalytic process depends strongly on the electronic and steric nature of the substrates. Part of the carbonyl functions of the catalyst can be replaced by phosphine ligands. Chiral DIOP reacts with the PtCl{sub 4}-CO compound to give a catalyst that promotes partial kinetic resolution of a racemic alkyne. Replacement of part of the CO by polystyrene-bound diphenylphosphine enables to attach the catalyst to the polymeric support. Upon entrapment of the platinum compound in a silica sol-gel matrix, it reacts as a partially recyclable catalyst. A reformulated mechanism for the PdCl{sub 4}-CO catalyzed hydration is suggested on the basis of the present study.

  15. Structural studies of β-turn-containing peptide catalysts for atroposelective quinazolinone bromination.

    Science.gov (United States)

    Metrano, A J; Abascal, N C; Mercado, B Q; Paulson, E K; Miller, S J

    2016-04-04

    We describe herein a crystallographic and NMR study of the secondary structural attributes of a β-turn-containing tetra-peptide, Boc-Dmaa-D-Pro-Acpc-Leu-NMe2, which was recently reported as a highly effective catalyst in the atroposelective bromination of 3-arylquinazolin-4(3H)-ones. Inquiries pertaining to the functional consequences of residue substitutions led to the discovery of a more selective catalyst, Boc-Dmaa-D-Pro-Acpc-Leu-OMe, the structure of which was also explored. This new lead catalyst was found to exhibit a type I'β-turn secondary structure both in the solid state and in solution, a structure that was shown to be an accessible conformation of the previously reported catalyst, as well.

  16. Studies on Sono-Chemical Biodiesel Production Using Smoke Deposited Nano MgO Catalyst

    Directory of Open Access Journals (Sweden)

    P. Sivakumar

    2013-12-01

    Full Text Available The comprehensive study of smoke deposited nano sized MgO as a catalyst for biodiesel production was investigated. The transesterification reaction was studied under constant ultrasonic mixing for different parameters like catalyst quantity, methanol oil molar ratio, reaction temperature and reaction time. An excellent result of conversion was obtained at 1.5 wt% catalyst; 5:1 methanol oil molar ratio at 55°C, a conversion of 98.7% was achieved after 45 min. The conversion was three to five times higher than those are reported for laboratory MgO in literature. This was mainly due to the enhancement of surface area of the catalyst and the activity of ultrasonic waves. Catalyst is easily recovered and reused up to eight times with easy regeneration steps.  © 2013 BCREC UNDIP. All rights reservedReceived: 18th March 2013; Revised: 20th August 2013; Accepted: 9th September 2013[How to Cite: Sivakumar, P., Sankaranarayanan, S., Renganathan, S., Sivakumar, P. (2013. Studies on Sono-Chemical Biodiesel Production Using Smoke Deposited Nano MgO Catalyst. Bulletin of Chemical Re-action Engineering & Catalysis, 8 (2: 89-96.(doi:10.9767/bcrec.8.2.4628.89-96][Permalink/DOI: http://dx.doi.org/10.9767/bcrec.8.2.4628.89-96

  17. HZSM-5 Catalyst for Cracking Palm Oil to Gasoline: A Comparative Study with and without Impregnation

    Directory of Open Access Journals (Sweden)

    Achmad Roesyadi

    2013-03-01

    Full Text Available It is important to develop a renewable source of energy to overcome a limited source fossil energy. Palm oil is a potential alternative and environmental friendly energy resource in Indonesia due to high production capacity of this vegetable oil. The research studied effect of catalyst to selectivity of biofuel product from cracking of palm oil. The catalyst consisted of HZSM-5 catalyst with or without impregnation. The research was conducted in two steps, namely catalyst synthesized and catalytic cracking process. HZSM-5 was synthesized using Plank methods. The characterization of the synthesized catalysts used AAS (Atomic Absorption Spectroscopy and BET (Brunaueur Emmet Teller. The cracking was carried out in a fixed bed microreactor with diameter of 1 cm and length of 16 cm which was filled with 0.6 gram catalyst. The Zn/HZSM-5 catalyst was recommended for cracking palm oil for the high selectivity to gasoline. © 2013 BCREC UNDIP. All rights reserved.(Selected Paper from International Conference on Chemical and Material Engineering (ICCME 2012Received: 28th September 2012; Revised: 19th November 2012; Accepted: 20th December 2012[How to Cite: A. Roesyadi, D. Hariprajitno, N. Nurjannah, S.D. Savitri, (2013. HZSM-5 Catalyst for Cracking Palm Oil to Gasoline: A Comparative Study with and without Impregnation. Bulletin of Chemical Reaction Engineering & Catalysis, 7 (3: 185-190.(doi:10.9767/bcrec.7.3.4045.185-190][Permalink/DOI: http://dx.doi.org/10.9767/bcrec.7.3.4045.185-190 ] View in  |

  18. Study on surface morphology and selectivity of precipitated iron catalysts of FTS

    Energy Technology Data Exchange (ETDEWEB)

    Wang Xingjun; Gao Miao; Hong Bingqing; Shang Guofeng; Li Ping; Liu Yu; Wang Fuchen; Yu Zunhong [Institute of Clean Coal Technology ECUST, Shanghai (China). Key Laboratory of Coal Gasification of Ministry of Education

    2009-09-15

    An iron catalyst was prepared by co-precipitation. The surface morphology of the catalyst was investigated under different reduction conditions by SEM (S-250, USA). Under H{sub 2}-reduction, the surface morphology of the catalyst had the obvious changes, which the diameter reduced, adhered together, came into being wads considered as a group. But the surface morphology of the catalyst had almost no change under CO reduction. The crystal structure of the catalyst was studied under different reduction conditions by X-ray diffraction (XRD) (Rigaku D/max, Japanese). It was found that the catalyst was reduced completely with H{sub 2}, but it was reduced partly with CO. The crystal structure of the catalyst converted into the metallic phase with H{sub 2} reduction. However, most of the iron converted into iron oxide (Fe{sub 3}O{sub 4}) with CO reduction. And the predominant phase in a sample of a mature catalyst is X-Fe{sub 5}C{sub 2}, which is the active phase in the Fischer-Tropsch synthesis (FTS). The experimental results showed that CO conversion and H{sub 2} conversion increase with the change of reaction temperature from 260 to 300{sup o}C, under the conditions of pressure P = 2.6 MPa, space velocity = 0.86 Nl h{sup -1} g-Fe{sup -1}, n(H{sub 2})/n(CO) = 2/3, and most of the hydrocarbon products are C{sub 5-11} which hold half of the hydrocarbon products. The next content is C{sub 2-4} which holds the quarter of hydrocarbon products. Then it is C{sub 12+}, which is equal to 18%. And the last is C{sub 1}, which is equal to 7%.

  19. STUDY OF SOLVENT AND CATALYST INTERACTIONS IN DIRECT COAL LIQUEFACTION

    Energy Technology Data Exchange (ETDEWEB)

    Michael T. Klein; William H. Calkins; Jasna Tomic

    2000-10-04

    To provide a better understanding of the roles of a solid catalyst and the solvent in Direct Coal Liquefaction, a small reactor was equipped with a porous-walled basket which was permeable to the solvent but was not permeable to the coal or solid catalyst. With this equipment and a high volatile bituminous coal it was found that direct contact between the catalyst in the basket and the coal outside the basket is not required for catalyzed coal liquefaction. The character of the solvent in this system makes a significant difference in the conversion of the coal, the better solvents being strong donor solvents. Because of the extensive use of thermogravimetric analysis in this laboratory, it was noted that the peak temperature for volatiles evolution from coal was a reliable measure of coal rank. Because of this observation, a variety of coals of a range of ranks was investigated. It was shown in this work that measuring the peak temperature for volatiles evolution was a quite precise indicator of rank and correlated closely with the rank value obtained by measuring vitrinite reflectance, a more difficult measurement to make. This prompted the desire to know the composition of the volatile material evolved as a function of coal rank. This was then measured by coupling a TGA to a mass spectrometer using laser activation and photoionization detection TG-PI-MS. The predominant species in volatiles of low rank coal turned out to be phenols with some alkenes. As the rank increases, the relative amounts of alkene and aromatic hydrocarbons increases and the oxygenated species decrease. It was shown that these volatiles were actually pyrolytic products and not volatilization products of the coal. Solvent extraction experiments coupled with Thermogravimetric-photoionization-mass spectrometry (TG-PI-MS) indicated that the low boiling and more extractable material are essentially similar in chemical types to the non-extractable portions but apparently higher molecular weight

  20. A study on production of biodiesel using a novel solid oxide catalyst derived from waste.

    Science.gov (United States)

    Majhi, Samrat; Ray, Srimanta

    2016-05-01

    The issues of energy security, dwindling supply and inflating price of fossil fuel have shifted the global focus towards fuel of renewable origin. Biodiesel, having renewable origin, has exhibited great potential as substitute for fossil fuels. The most common route of biodiesel production is through transesterification of vegetable oil in presence of homogeneous acid or base or solid oxide catalyst. But, the economics of biodiesel is not competitive with respect to fossil fuel due to high cost of production. The vegetable oil waste is a potential alternative for biodiesel production, particularly when disposal of used vegetable oil has been restricted in several countries. The present study evaluates the efficacy of a low-cost solid oxide catalyst derived from eggshell (a food waste) in transesterification of vegetable oil and simulated waste vegetable oil (SWVO). The impact of thermal treatment of vegetable oil (to simulate frying operation) on transesterification using eggshell-derived solid oxide catalyst (ESSO catalyst) was also evaluated along with the effect of varying reaction parameters. The study reported that around 90 % biodiesel yield was obtained with vegetable oil at methanol/oil molar ratio of 18:1 in 3 h reaction time using 10 % ESSO catalyst. The biodiesel produced with ESSO catalyst from SWVO, thermally treated at 150 °C for 24 h, was found to conform with the biodiesel standard, but the yield was 5 % lower compared to that of the untreated oil. The utilization of waste vegetable oil along with waste eggshell as catalyst is significant for improving the overall economics of the biodiesel in the current market. The utilization of waste for societal benefit with the essence of sustainable development is the novelty of this work.

  1. Rare-isotope and kinetic studies of Pt/SnO2 catalysts

    Science.gov (United States)

    Upchurch, Billy T.; Wood, George M.; Schryer, David R.; Hess, Robert V.; Miller, Irvin M.; Kielin, Erik J.

    1990-01-01

    Closed-cycle pulsed CO2 laser operation requires the use of an efficient CO-O2 recombination catalyst for these dissociation products which otherwise would degrade the laser operation. The catalyst must not only operate at low temperatures but also must operate efficiently for long periods. In the case of the Laser Atmospheric Wind Sounder (LAWS) laser, an operational lifetime of 3 years is required. Additionally, in order to minimize atmospheric absorption and enhance aerosol scatter of laser radiation, the LAWS system will operate at 9.1 micrometers with an oxygen-18 isotope CO2 lasing medium. Consequently, the catalyst must not only operate at low temperatures but must also preserve the isotopic integrity of the rare-isotope composition in the recombination mode. Several years ago an investigation of commercially available and newly synthesized recombination catalysts for use in closed-cycle pulsed common and rare-isotope CO2 lasers was implemented at the NASA Langley Research Center. Since that time, mechanistic efforts utilizing both common and rare oxygen isotopes have been implemented and continue. Rare-isotope studies utilizing commercially available platinum-tin oxide catalyst have demonstrated that the catalyst contributes oxygen-16 to the product carbon dioxide thus rendering it unusable for rare-isotope applications. A technique has been developed for modification of the surface of the common-isotope catalyst to render it usable. Results of kinetic and isotope label studies using plug flow, recycle plug flow, and closed internal recycle plug flow reactor configuration modes are discussed.

  2. Model heterogeneous acid catalysts and metal-support interactions: A combined surface science and catalysis study

    Energy Technology Data Exchange (ETDEWEB)

    Boszormenyi, Istvan [Univ. of California, Berkeley, CA (United States)

    1991-05-01

    This (<100Å) silica-alumina layers were tested as potential model heterogeneous acid catalysts for combined surface science and catalysis studies. Three preparation methods were used: oxidation of r3 x r3 R30 Al/Si(111) structure in UHV; deposition on Si(lll) from aqueous solution; and argon ion beam sputter deposition in UHV. The homogeneous thin layers are amorphous, and the chemical environment of surface atoms is similar to that of Si, Al and oxygen atoms on high surface area acid catalysts. Since the ion beam-deposited thin layer of silica-alumina has the same composition as the target zeolite this deposition method is a promising tool to prepare model catalysts using practical catalyst targets. The silica-alumina layers are active in cumene cracking, a typical acid catalyzed reaction. In order to clearly distinguish background reactions and the acid catalyzed reaction at least 20 cm2 catalyst surface area is needed. Two series of model platinum-alumina catalysts were prepared in a combined UHV -- high pressure reactor cell apparatus by depositing alumina on polycrystalline Pt foil and by vapor depositing Pt on a thin alumina layer on Au. Both model surfaces have been prepared with and without chlorine. AES, CO desorption as well as methyl cyclopentane (MCP) hydrogenolysis studies indicate that the Pt surface area is always higher if a chlorination step is involved. Selectivity patterns in MCP ring opening on ``Pt-on-alumina`` and on ``alumina-on-Pt`` are different; only the former is a linear combination of selective and statistical ring opening. Product distribution, however, changes with coverage and reaction time. The properties of the two model catalyst systems and role of chlorine in MCP hydrogenolysis are also discussed.

  3. Model heterogeneous acid catalysts and metal-support interactions: A combined surface science and catalysis study

    Energy Technology Data Exchange (ETDEWEB)

    Boszormenyi, I.

    1991-05-01

    This (<100 [Angstrom]) silica-alumina layers were tested as potential model heterogeneous acid catalysts for combined surface science and catalysis studies. Three preparation methods were used: oxidation of r3 [times] r3 R30 Al/Si(111) structure in UHV; deposition on Si(lll) from aqueous solution; and argon ion beam sputter deposition in UHV. The homogeneous thin layers are amorphous, and the chemical environment of surface atoms is similar to that of Si, Al and oxygen atoms on high surface area acid catalysts. Since the ion beam-deposited thin layer of silica-alumina has the same composition as the target zeolite this deposition method is a promising tool to prepare model catalysts using practical catalyst targets. The silica-alumina layers are active in cumene cracking, a typical acid catalyzed reaction. In order to clearly distinguish background reactions and the acid catalyzed reaction at least 20 cm[sup 2] catalyst surface area is needed. Two series of model platinum-alumina catalysts were prepared in a combined UHV -- high pressure reactor cell apparatus by depositing alumina on polycrystalline Pt foil and by vapor depositing Pt on a thin alumina layer on Au. Both model surfaces have been prepared with and without chlorine. AES, CO desorption as well as methyl cyclopentane (MCP) hydrogenolysis studies indicate that the Pt surface area is always higher if a chlorination step is involved. Selectivity patterns in MCP ring opening on Pt-on-alumina'' and on alumina-on-Pt'' are different; only the former is a linear combination of selective and statistical ring opening. Product distribution, however, changes with coverage and reaction time. The properties of the two model catalyst systems and role of chlorine in MCP hydrogenolysis are also discussed.

  4. Fundamental Studies of the Reforming of Oxygenated Compounds over Supported Metal Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Dumesic, James A. [Univ. of Wisconsin, Madison, WI (United States)

    2016-01-04

    microcopy (STEM) to measure size and structure, energy dispersive X-ray spectroscopy (EDS) to measure atomic composition, X-ray absorption spectroscopy (XAS) to measure oxidation state and metal coordination, Fourier transform infrared spectroscopy (FTIR) to study adsorbed species, laser Raman spectroscopy to probe metal oxide promoters, and temperature programmed reaction/desorption to study the energetics of adsorption and desorption processes. We have studied our bimetallic catalysts for the selective cleavage of carbon-oxygen bonds, and we have studied the effects of adding metal oxide promoters to supported platinum and gold catalysts for water-gas shift (i.e., the production of hydrogen by reaction of carbon monoxide with water). We anticipate that the knowledge obtained from our studies will allow us to identify promising directions for new catalysts that show high activity, selectivity, and stability for important reactions, such as the conversion of biomass-derived oxygenated hydrocarbons to fuels and chemicals.

  5. A study on the polymer catalyst process technology

    Energy Technology Data Exchange (ETDEWEB)

    Chung, H.; Lee, H. S.; Ahn, D. H.; Kim, K. R.; Kang, H. S.; Paek, S. W.; Lee, S. H.; Sung, K. W.

    1997-06-01

    Heavy water is used as moderator and coolant in Pressurized Heavy Water Power Plants. According to the governmental long-term plan for power supply Korea is scheduled to construct and operate total four pressurized heavy water power plant till the year 1999. Total heavy water make-up for these plants would be 18 Mg/a from the year 1999. Reformed hydrogen processes is considered best suited to Korea. Polymer catalysts for this process were manufactured and the performance of hydrogen isotope exchange was investigated. The overall mass transfer coefficients varied between 0.004 and 2.295 m{sup 3}.HD/m{sup 3} Bed.sec. and heavy water separation process using the catalysis were optimized. (author). 102 refs., 134 tabs., 65 figs.

  6. Pulsed-field gradient nuclear magnetic resonance study of transport properties of fluid catalytic cracking catalysts.

    Science.gov (United States)

    Kortunov, P; Vasenkov, S; Kärger, J; Fé Elía, M; Perez, M; Stöcker, M; Papadopoulos, G K; Theodorou, D; Drescher, B; McElhiney, G; Bernauer, B; Krystl, V; Kocirik, M; Zikanova, A; Jirglova, H; Berger, C; Gläser, R; Weitkamp, J; Hansen, E W

    2005-02-01

    Pulsed-field gradient nuclear magnetic resonance (PFG NMR) has been applied to study molecular diffusion in industrial fluid catalytic cracking (FCC) catalysts and in USY zeolite for a broad range of molecular displacements and temperatures. The results of this study have been used to elucidate the relevance of molecular transport on various displacements for the rate of molecular exchange between catalyst particles and their surroundings. It turned out that this rate, which may determine the overall rate and selectivity of FCC process, is primarily related to the diffusion mode associated with displacements larger than the size of zeolite crystals located in the particles but smaller than the size of the particles. This conclusion has been confirmed by comparative studies of the catalytic performance of different FCC catalysts.

  7. Experimental Study and Kinetic Modeling of Decoking of Pacol Process Dehydrogenation Catalyst

    Directory of Open Access Journals (Sweden)

    M. Toghyani

    2015-07-01

    Full Text Available The Pt/γ-Al2O3 catalyst life time was limited by the formation of coke on the external and internal surfaces of catalyst in dehydrogenation reactors. The kinetics of decoking of dehydrogenation catalyst was studied in a pilot scale fixed bed reactor experimentally. The effects of temperature, oxygen concentration and other operating conditions on decoking process were investigated. A kinetic model was deve-loped to describe the decoking of mentioned catalyst. An objective function was defined as the sum of squares of the deviations among the calculated and plant data. Accordingly the appropriate values were found in order to minimize this function. It was concluded that there was a good agreement between simulation results and experimental data.  © 2015 BCREC UNDIP. All rights reservedReceived: 18th September 2014; Revised: 28th February 2015; Accepted: 9th March 2015How to Cite: Toghyani, M., Rahimi, A., Mamanpoush, M., Kazemian, R., Harandizadeh, A.H. (2015. Experimental Study and Kinetic Modeling of Decoking of Pacol Process Dehydrogenation Catalyst. Bulletin of Chemical Reaction Engineering & Catalysis, 10 (2: 155-161. (doi:10.9767/bcrec.10.2.7357.155-161 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.10.2.7357.155-161  

  8. N,N,N′,N′-Tetramethyl-N′′-[3-(trimethylazaniumylpropyl]guanidinium bis(tetraphenylborate acetone disolvate

    Directory of Open Access Journals (Sweden)

    Ioannis Tiritiris

    2013-03-01

    Full Text Available In the title solvated salt, C11H28N42+·2C24H20B−·2C3H6O, the C—N bond lengths in the central CN3 unit of the guanidinium ion are 1.3331 (16, 1.3407 (16 and 1.3454 (16 Å, indicating partial double-bond character in each. The central C atom is bonded to the three N atoms in a nearly ideal trigonal–planar geometry [N—C—N angles = 118.96 (11, 120.51 (12 and 120.53 (11°] and the positive charge is delocalized in the CN3 plane. The bonds between the N atoms and the terminal C-methyl groups of the guanidinium moiety all have values close to a typical single bond [1.4601 (16–1.4649 (16 Å]. In the crystal, the guanidinium ion is connected by N—H...O and C—H...O hydrogen bonds with the acetone molecules. C—H...π interactions are present between the guanidinium H atoms and the phenyl rings of both tetraphenylborate ions. The phenyl rings form aromatic pockets, in which the guanidinium ions are embedded.

  9. Study on Corrosion Migrations within Catalyst-Coated Membranes of Proton Exchange Membrane Electrolyzer Cells

    Energy Technology Data Exchange (ETDEWEB)

    Green, Johney [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Mo, Jingke [University of Tennessee; Steen, Stuart [University of Tennessee; Kang, Zhenye [University of Tennessee; Yang, Gaoqiang [University of Tennessee; Taylor, Derrick A. [University of Tennessee; Li, Yifan [University of Tennessee; Toops, Todd J. [Oak Ridge National Laboratory; Brady, Michael P. [Oak Ridge National Laboratory; Retterer, Scott T. [Oak Ridge National Laboratory; Cullen, David A. [Oak Ridge National Laboratory; Zhang, Feng-Yuan [University of Tennessee

    2017-10-09

    The corrosion of low-cost, easily manufactured metallic components inside the electrochemical environment of proton exchange membrane electrolyzer cells (PEMECs) has a significant effect on their performance and durability. In this study, 316 stainless steel (SS) mesh was used as a model liquid/gas diffusion layer material to investigate the migration of corrosion products in the catalyst-coated membrane of a PEMEC. Iron and nickel cation particles were found distributed throughout the anode catalyst layer, proton exchange membrane, and cathode catalyst layer, as revealed by scanning transmission electron microscopy and energy dispersive X-ray spectroscopy. The results indicate the corrosion products of 316 SS are transported from anode to cathode through the nanochannels of the Nafion membrane, resulting in impeded proton transport and overall PEMEC performance loss.

  10. Determinants and Catalysts in Intrafirm Technology Transfer: Learning From Case Studies

    Directory of Open Access Journals (Sweden)

    Giorgio Petronia

    2015-04-01

    Full Text Available The sharing of technological knowledge between firms or within the same firm is becoming essential to develop innovations. Although previous studies have investigated the determinants of technology transfer(TT, they have not pointed out the existence of catalysts, i.e. determinants that assume a more crucial role than others in making transfer effective, and which compensate for the weaknesses in other determinants. In this paper, from the analysis of transfer processes within three manufacturing multinationals, three catalysts have emerged: leadership by the top management, anticipated profitability from the adoption of the new technology, and the professionalism of centralized research and development staff.

  11. Structural Studies of ?-Turn-Containing Peptide Catalysts for Atroposelective Quinazolinone Bromination?

    OpenAIRE

    Metrano, A. J.; Abascal, N. C.; Mercado, B. Q.; Paulson, E. K.; Miller, S. J.

    2016-01-01

    We describe herein a crystallographic and NMR study of the secondary structural attributes of a ?-turn-containing tetra-peptide, Boc-Dmaa-D-Pro-Acpc-Leu-NMe2, which was recently reported as a highly effective catalyst in the atroposelective bromination of 3-arylquinazolin-4(3H)-ones. Inquiries pertaining to the functional consequences of residue substitutions led to the discovery of a more selective catalyst, Boc-Dmaa-D-Pro-Acpc-Leu-OMe, the structure of which was also explored. This new lead...

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

    OpenAIRE

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

    2016-01-01

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

  13. An introductory study of multifunctional catalysts for ethanol and biogas vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Pettersson, L.J.; Wahlberg, A.M.; Jaeraas, S.G. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Chemical Technology

    1998-03-01

    The long-term goal for the project is to develop highly efficient exhaust gas catalysts for heavy-duty vehicles fuelled by biobased motor fuels operating in urban traffic. In this report an experimental study of catalytic oxidation of ethanol in a laboratory flow reactor is presented. The miniature catalyst samples consisted of monolithic cordierite substrates onto which various combinations of washcoat material and active material were applied. The experimental conditions were chosen in order to simulate the composition of the exhaust from a diesel engine fuelled by neat ethanol. A series of precious metal-based catalysts has been tested where different metal loadings and different complex washcoat compositions have been evaluated. Earlier studies have been concentrated on model washcoats such as alumina, ceria, silica, and titania (see KFB Report 1997:40). The choice of materials for the complex washcoats is based on the results from these experiments. One of the catalysts with the advanced washcoat Z exhibits lower light-off temperatures (T{sub 50}) for ethanol oxidation than the corresponding catalysts with washcoat X. The by-product formation shows a more complex picture. A number of parallel and consecutive reactions occur simultaneously in the reactor, where formation of acetaldehyde is by far the most common. Generally, the formation of acetaldehyde follows the conversion of ethanol, so that the catalysts with the lowest light-off temperature also form most acetaldehyde. If the peak for acetaldehyde formation can be shifted towards 150 deg C or temperatures below, this means that the acetaldehyde formation will not occur in practical fleet operation, since this is outside the normal exhaust temperature of the engine 26 figs, 4 tabs

  14. Low-temperature catalyst activator: mechanism of dense carbon nanotube forest growth studied using synchrotron radiation

    Directory of Open Access Journals (Sweden)

    Akito Takashima

    2014-07-01

    Full Text Available The mechanism of the one-order-of-magnitude increase in the density of vertically aligned carbon nanotubes (CNTs achieved by a recently developed thermal chemical vapor deposition process was studied using synchrotron radiation spectroscopic techniques. In the developed process, a Ti film is used as the underlayer for an Fe catalyst film. A characteristic point of this process is that C2H2 feeding for the catalyst starts at a low temperature of 450°C, whereas conventional feeding temperatures are ∼800°C. Photoemission spectroscopy using soft and hard X-rays revealed that the Ti underlayer reduced the initially oxidized Fe layer at 450°C. A photoemission intensity analysis also suggested that the oxidized Ti layer at 450°C behaved as a support for nanoparticle formation of the reduced Fe, which is required for dense CNT growth. In fact, a CNT growth experiment, where the catalyst chemical state was monitored in situ by X-ray absorption spectroscopy, showed that the reduced Fe yielded a CNT forest at 450°C. Contrarily, an Fe layer without the Ti underlayer did not yield such a CNT forest at 450°C. Photoemission electron microscopy showed that catalyst annealing at the conventional feeding temperature of 800°C caused excess catalyst agglomeration, which should lead to sparse CNTs. In conclusion, in the developed growth process, the low-temperature catalyst activation by the Ti underlayer before the excess Fe agglomeration realised the CNT densification.

  15. Stability and kinetic studies of supported ionic liquid phase catalysts for hydroformylation of propene

    DEFF Research Database (Denmark)

    Riisager, Anders; Fehrmann, Rasmus; Haumann, Marco

    2005-01-01

    Supported ionic liquid phase (SILP) catalysts have been studied with regard to their long-term stability in the continuous gas-phase hydroformylation of propene. Kinetic data have been acquired by variation of temperature, pressure, syngas composition, substrate concentration, and residence time...

  16. Impregnation of mesoporous silica for catalyst preparation studied with differential scanning calorimetry

    NARCIS (Netherlands)

    Eggenhuisen, T.M.|info:eu-repo/dai/nl/313959498; van Steenbergen, M.J.|info:eu-repo/dai/nl/304839302; Talsma, H.|info:eu-repo/dai/nl/08138212X; de Jongh, P.E.|info:eu-repo/dai/nl/186125372; de Jong, K.P.|info:eu-repo/dai/nl/06885580X

    2009-01-01

    Aqueous impregnation of mesoporous silica as a first step in catalyst preparation was studied to investigate the distribution of the metal-precursor solution over the support. The degree of pore-filling after impregnation was determined using the freezing point depression of confined liquids. A

  17. Exploratory catalyst screening studies on the liquefaction of model humins from C6 sugars

    NARCIS (Netherlands)

    Wang, Y.; Agarwal, S.; Tang, Z.; Heeres, H. J.

    2017-01-01

    A catalyst screening study is reported on the liquefaction of humins, the solid byproducts from C6 sugar biorefineries for levulinic acid and 5-hydroxymethylfurfural production. Experiments were carried out in a batch reactor using an artificial model of humin derived from glucose with isopropanol

  18. Hydrodeoxygenation of waste fat for diesel production: Study on model feed with Pt/alumina catalyst

    DEFF Research Database (Denmark)

    Madsen, Anders Theilgaard; Ahmed, El Hadi; Christensen, Claus H.

    2011-01-01

    Hydrodeoxygenation of waste fats and oils is a viable method for producing renewable diesel oil. In this study a model feed consisting of oleic acid and tripalmitin in molar ratio 1:3 was hydrotreated at 325°C with 20bars H2 in a stirred batch autoclave with a 5wt% Pt/γ-Al2O3 catalyst, and sample...

  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. A Comparative Study of Solvothermal and Sol-Gel-Derived Nanocrystalline Alumina Catalysts for Ethanol Dehydration

    Directory of Open Access Journals (Sweden)

    Mingkwan Wannaborworn

    2015-01-01

    Full Text Available The ethanol dehydration to ethylene over alumina catalysts prepared by solvothermal and sol-gel methods was investigated. Also, a commercial alumina was used for comparison purposes. The results showed that the catalytic activity depends on the properties of catalyst derived from different preparation methods and reaction temperature. The alumina synthesized by solvothermal method exhibited the highest activity. This can be attributed to the higher surface area and larger amount of acid site, especially the ratio of weak/strong acid strength as determined by N2 physisorption and NH3-TPD studies. The solvothermal-derived catalyst exhibited an excellent performance with complete ethanol conversion and 100% selectivity to ethylene at 350°C in comparison with other ones. In addition, we further studied the catalytic dehydration of alumina catalyst modified with Fe. The presence of 10 wt.% Fe decreased both conversion and ethylene selectivity. However, the acetaldehyde selectivity apparently increased. It was related to the dehydrogenation pathway that takes place on Fe species.

  1. Making fired bricks with spent equilibrium catalyst-a technical feasibility study

    Science.gov (United States)

    Chou, M.-L.; Chen, L.-M.; Lai, Y.-C.; Chou, S.-F.

    2009-01-01

    Fluid catalytic cracking in an oil refinery uses a catalyst, such as an alumino-silicate zeolite, in the conversion of heavy hydrocarbons to light hydrocarbons. A small fraction of the catalyst is continually replaced with fresh catalyst to maintain activity. In North America, more than 400 tons of spent alumino-silicate equilibrium catalyst (spent e-cat), and worldwide, more than 1,100 tons, are generated daily, most of which is disposed of in landfills (municipal and on-site facilities). In this study, three spent e-cat samples were tested in a value-added application that would utilize this waste in the manufacturing of fired bricks. The results of this study indicate that spent e-cat is a technically feasible raw material substitute for the clay and shale commonly used in fired brick production. Fired bricks produced with up to 30 wt% of spent e-cat showed good physical appearance and their water absorption properties met the ASTM C 62 specifications for building bricks of either the moderate-or severe-weathering grade.

  2. Production of biofuel from waste cooking palm oil using nanocrystalline zeolite as catalyst: process optimization studies.

    Science.gov (United States)

    Taufiqurrahmi, Niken; Mohamed, Abdul Rahman; Bhatia, Subhash

    2011-11-01

    The catalytic cracking of waste cooking palm oil to biofuel was studied over different types of nano-crystalline zeolite catalysts in a fixed bed reactor. The effect of reaction temperature (400-500 °C), catalyst-to-oil ratio (6-14) and catalyst pore size of different nanocrystalline zeolites (0.54-0.80 nm) were studied over the conversion of waste cooking palm oil, yields of Organic Liquid Product (OLP) and gasoline fraction in the OLP following central composite design (CCD). The response surface methodology was used to determine the optimum value of the operating variables for maximum conversion as well as maximum yield of OLP and gasoline fraction, respectively. The optimum reaction temperature of 458 °C with oil/catalyst ratio=6 over the nanocrystalline zeolite Y with pore size of 0.67 nm gave 86.4 wt% oil conversion, 46.5 wt% OLP yield and 33.5 wt% gasoline fraction yield, respectively. The experimental results were in agreement with the simulated values within an experimental error of less than 5%. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. 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

  4. Reaction selectivity studies on nanolithographically-fabricated platinum model catalyst arrays

    Energy Technology Data Exchange (ETDEWEB)

    Grunes, Jeffrey Benjamin [Univ. of California, Berkeley, CA (United States)

    2004-05-01

    In an effort to understand the molecular ingredients of catalytic activity and selectivity toward the end of tuning a catalyst for 100% selectivity, advanced nanolithography techniques were developed and utilized to fabricate well-ordered two-dimensional model catalyst arrays of metal nanostructures on an oxide support for the investigation of reaction selectivity. In-situ and ex-situ surface science techniques were coupled with catalytic reaction data to characterize the molecular structure of the catalyst systems and gain insight into hydrocarbon conversion in heterogeneous catalysis. Through systematic variation of catalyst parameters (size, spacing, structure, and oxide support) and catalytic reaction conditions (hydrocarbon chain length, temperature, pressures, and gas composition), the data presented in this dissertation demonstrate the ability to direct a reaction by rationally adjusting, through precise control, the design of the catalyst system. Electron beam lithography (EBL) was employed to create platinum nanoparticles on an alumina (Al2O3) support. The Pt nanoparticle spacing (100-150-nm interparticle distance) was varied in these samples, and they were characterized using x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM), both before and after reactions. The TEM studies showed the 28-nm Pt nanoparticles with 100 and 150-nm interparticle spacing on alumina to be polycrystalline in nature, with crystalline sizes of 3-5 nm. The nanoparticle crystallites increased significantly after heat treatment. The nanoparticles were still mostly polycrystalline in nature, with 2-3 domains. The 28-nm Pt nanoparticles deposited on alumina were removed by the AFM tip in contact mode with a normal force of approximately 30 nN. After heat treatment at 500 C in vacuum for 3 hours, the AFM tip, even at 4000 nN, could not remove the platinum

  5. Spectroscopic and structural elucidation of merocyanine dye 2,5-[1-metyl-4-[2-(4-hydroxyphenyl)ethenyl)]piridinium]-hexane tetraphenylborate. Aggregation processes

    Science.gov (United States)

    Koleva, Bojidarka B.; Stoyanov, Stanimir; Kolev, Tsonko; Petkov, Ivan; Spiteller, Michael

    2008-12-01

    Structural and spectroscopic elucidation of merocyanine dye, 2,5-[1-metyl-4-[2-(4-hydroxyphenyl)ethenyl)]piridinium]-hexane tetraphenylborate, is performed in gas and condense phase by means of solution and solid-state conventional and linear-polarized IR-spectroscopy of oriented colloids in nematic liquid crystal suspension, UV-vis and fluorescence methods, HPLC MS/MS tandem and ESI mass spectrometry, 1H, 13C and 1H- 1H COSY NMR, TGV and DSC methods. Quantum chemical DFT calculations are performed for structural optimization and spectroscopic properties prediction.

  6. Why does the Conductivity of a Nickel Catalyst Increase during Sulfidation? An Exemplary Study Using an In Operando Sensor Device

    Directory of Open Access Journals (Sweden)

    Peter Fremerey

    2015-10-01

    Full Text Available In order to study the sulfidation of a catalyst fixed bed, an in operando single pellet sensor was designed. A catalyst pellet from the fixed bed was electrically contacted and its electrical response was correlated with the catalyst behavior. For the sulfidation tests, a nickel catalyst was used and was sulfidized with H2S. This catalyst had a very low conductivity in the reduced state. During sulfidation, the conductivity of the catalyst increased by decades. A reaction from nickel to nickel sulfide occurred. This conductivity increase by decades during sulfidation had not been expected since both nickel and nickel sulfides behave metallic. Only by assuming a percolation phenomenon that originates from a volume increase of the nickel contacts when reacting to nickel sulfides, this effect can be explained. This assumption was supported by sulfidation tests with differently nickel loaded catalysts and it was quantitatively estimated by a general effective media theory. The single pellet sensor device for in operando investigation of sulfidation can be considered as a valuable tool to get further insights into catalysts under reaction conditions.

  7. Why does the Conductivity of a Nickel Catalyst Increase during Sulfidation? An Exemplary Study Using an In Operando Sensor Device.

    Science.gov (United States)

    Fremerey, Peter; Jess, Andreas; Moos, Ralf

    2015-10-23

    In order to study the sulfidation of a catalyst fixed bed, an in operando single pellet sensor was designed. A catalyst pellet from the fixed bed was electrically contacted and its electrical response was correlated with the catalyst behavior. For the sulfidation tests, a nickel catalyst was used and was sulfidized with H₂S. This catalyst had a very low conductivity in the reduced state. During sulfidation, the conductivity of the catalyst increased by decades. A reaction from nickel to nickel sulfide occurred. This conductivity increase by decades during sulfidation had not been expected since both nickel and nickel sulfides behave metallic. Only by assuming a percolation phenomenon that originates from a volume increase of the nickel contacts when reacting to nickel sulfides, this effect can be explained. This assumption was supported by sulfidation tests with differently nickel loaded catalysts and it was quantitatively estimated by a general effective media theory. The single pellet sensor device for in operando investigation of sulfidation can be considered as a valuable tool to get further insights into catalysts under reaction conditions.

  8. Catalytic Activity Studies of Vanadia/Silica–Titania Catalysts in SVOC Partial Oxidation to Formaldehyde: Focus on the Catalyst Composition

    Directory of Open Access Journals (Sweden)

    Niina Koivikko

    2018-02-01

    Full Text Available In this work, silica–titania supported catalysts were prepared by a sol–gel method with various compositions. Vanadia was impregnated on SiO2-TiO2 with different loadings, and materials were investigated in the partial oxidation of methanol and methyl mercaptan to formaldehyde. The materials were characterized by using N2 physisorption, X-ray diffraction (XRD, X-ray fluorescence spectroscopy (XRF, X-ray photoelectron spectroscopy (XPS, Scanning transmission electron microscope (STEM, NH3-TPD, and Raman techniques. The activity results show the high importance of an optimized SiO2-TiO2 ratio to reach a high reactant conversion and formaldehyde yield. The characteristics of mixed oxides ensure a better dispersion of the active phase on the support and in this way increase the activity of the catalysts. The addition of vanadium pentoxide on the support lowered the optimal temperature of the reaction significantly. Increasing the vanadia loading from 1.5% to 2.5% did not result in higher formaldehyde concentration. Over the 1.5%V2O5/SiO2 + 30%TiO2 catalyst, the optimal selectivity was reached at 415 °C when the maximum formaldehyde concentration was ~1000 ppm.

  9. Peer Study Groups as Catalyst for Vocational Exploration

    Science.gov (United States)

    Arendale, David R.; Hane, Amanda R.

    2016-01-01

    Postsecondary peer assisted learning programs often cite improving academic achievement for students. This qualitative study investigated the potential effect of serving as student facilitators of a peer study group on their future vocation. This was a replication of previous studies of personal and professional outcomes for study group…

  10. From porphyrins to pyrphyrins: adsorption study and metalation of a molecular catalyst on Au(111)

    OpenAIRE

    Mette Gerson; Sutter Denys; Gurdal Yeliz; Schnidrig Stephan; Probst Benjamin; Iannuzzi Marcella; Hutter Jürg; Alberto Roger; Osterwalder Jürg

    2016-01-01

    The molecular ligand pyrphyrin, a tetradentate bipyridine based macrocycle, represents an interesting but widely unexplored class of molecules. It resembles the well-known porphyrin, but consists of pyridyl subunits instead of pyrroles. Metal complexes based on pyrphyrin ligands have recently shown promise as water reduction catalysts in homogeneous photochemical water splitting reactions. In this study, the adsorption and metalation of pyrphyrin on a single crystalline Au(111) surface is inv...

  11. Explorative catalyst screening studies on reforming of glycerol in supercritical water

    NARCIS (Netherlands)

    van Bennekom, J. G.; Kirillov, V. A.; Amosov, Y. I.; Krieger, T.; Venderbosch, R. H.; Assink, D.; Lemmens, K. P. J.; Heeres, H. J.

    2012-01-01

    An explorative screening study with Pt/CeZrO2, Ni/ZrO2. Ni/CaO-6Al(2)O(3), NiCu/CeZrO2, and a CuZn alloy was carried out to investigate the influence of different catalysts on the carbon-to-gas efficiency and gas composition in the reforming of glycerol in supercritical water. Experiments were

  12. In Situ Raman Spectroscopy of Supported Chromium Oxide Catalysts: Reactivity Studies with Methanol and Butane

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Wachs, I.E.

    1996-01-01

    The interactions of methanol and butane with supported chromium oxide catalysts under oxidizing and reducing conditions were studied by in situ Raman spectroscopy as a function of the specific oxide support (Al2O3, ZrO2, TiO2, SiO2, Nb2O5, 3% SiO2/TiO2, 3% TiO2/SiO2, and a physical mixture of SiO2

  13. Evaluating the NOx Storage Catalysts (NSC Aging: A Preliminary Analytical Study with Electronic Microscopy

    Directory of Open Access Journals (Sweden)

    Leonarda Bellebuono

    2017-10-01

    Full Text Available This paper describes an expeditious and reliable method for determining the thermal effects in a static condition of commercial NOx storage catalysts (NSCs using scanning electron microscopy with an energy dispersive X-ray analytical system (SEM/EDS. It is worth remarking that possible changes in the morphology and in the elemental composition of the catalyst may be considered as the most important causes of the lower conversion of NOx. The information attained in this work indicates that Pt nanoparticle sintering is strongly increased by the oxygen exposure, and this can be considered a very useful preliminary investigation for the studies already present in the literature on the efficiency of NSCs.

  14. Moessbauer study of modified iron-molybdenum catalysts for methanol oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, K I; Krustev, St V [Agricultural University, Department of Chemistry, 12 Mendeleev St., 4000 Plovdiv (Bulgaria); Mitov, I G [Institute of Catalysis, Bulgarian Academy of Science, 1113 Sofia (Bulgaria); Boyanov, B S, E-mail: kivanov1@abv.b [Plovdiv University ' Paisii Hilendarski' , 24 Tsar Assen St., 4000 Plovdiv (Bulgaria)

    2010-03-01

    The preparation and catalytic properties of mixed Fe-Mo-W catalysts toward methanol oxidation are investigated. Moessbauer spectroscopy, X-ray diffraction and chemical studies revealed the formation of two types of solid solutions with compositions Fe{sub 2}(Mo{sub x}W{sub 1-x}O{sub 4}){sub 3} and (Mo{sub x}W{sub 1-x})O{sub 3}. The solid solutions formed are characterized by high activity and selectivity upon methanol oxidation and are of interest in view of their practical application. Sodium-doped iron-molybdenum catalysts are also investigated and the NaFe(MoO{sub 4}){sub 2} formation was established.

  15. Catalytic Conversion of Biomass Pyrolysis Vapours over Sodium-Based Catalyst; A Study on teh State of Sodium on the Catalyst

    NARCIS (Netherlands)

    Nguyen, T.S.; Lefferts, Leonardus; Gupta, K.B. Sai Sankar; Seshan, Kulathuiyer

    2015-01-01

    In situ upgrading of biomass pyrolysis vapours over Na2CO3/γ-Al2O3 catalysts was studied in a laboratory-scale fixed-bed reactor at 500 °C. Catalytic oil exhibits a significant improvement over its non-catalytic counterpart, such as lower oxygen content (12.3 wt % compared to 42.1 wt %), higher

  16. Preparation of Fe2O3-Clorprenaline/Tetraphenylborate Nanospheres and Their Application as Ion Selective Electrode for Determination of Clorprenaline in Pork

    Science.gov (United States)

    Shao, Xintian; Zhang, Jing; Li, Donghui; Yue, Jingli; Chen, Zhenhua

    2016-04-01

    A novel modified ion selective electrode based on Fe2O3-clorprenaline/tetraphenylborate nanospheres (Fe2O3-CLPT NSs) as electroactive materials for the determination of clorprenaline hydrochloride (CLP) is described. The α-Fe2O3 nanoparticles (NPs) were prepared by hydrothermal synthesis, then self-assembled on CLP/tetraphenylborate (TPB) to form Fe2O3-CLPT NSs, which were used as a potentiometric electrode for analyte determination innovatively. The Fe2O3-CLPT NSs modified electrode exhibited a wider concentration range from 1.0 × 10-7 to 1.0 × 10-1 mol/L and a lower detection limit of 3.7 × 10-8 mol/L compared with unmodified electrodes. The selectivity of the modified electrode was evaluated by fixed interference method. The good performance of the modified electrode such as wide pH range (2.4-6.7), fast response time (15 s), and adequate lifetime (14 weeks) indicate the utility of the modified electrode for evaluation of CLP content in various real samples. Finally, the modified electrode was successfully employed to detect CLP in pork samples with satisfactory results. These results demonstrated the Fe2O3-CLPT NSs modified electrode to be a functional and convenient method to the field of potentiometry determination of CLP in real samples.

  17. Theoretical Study on Nano-Catalyst Burn Rate

    Science.gov (United States)

    2014-11-26

    adsorption energy of 4.98 eV) is associated with formation NH3 and HClO4 molecules as shown in Figure 4. Thus, from the cluster calculations, it...Following the adsorption process of AP on anatase TiO2 (001) surface as well as on TiO2 clusters, the formation of NH3 and HClO4 molecules was studied

  18. Thermal conductivity of catalyst layer of polymer electrolyte membrane fuel cells: Part 1 - Experimental study

    Science.gov (United States)

    Ahadi, Mohammad; Tam, Mickey; Saha, Madhu S.; Stumper, Jürgen; Bahrami, Majid

    2017-06-01

    In this work, a new methodology is proposed for measuring the through-plane thermal conductivity of catalyst layers (CLs) in polymer electrolyte membrane fuel cells. The proposed methodology is based on deconvolution of bulk thermal conductivity of a CL from measurements of two thicknesses of the CL, where the CLs are sandwiched in a stack made of two catalyst-coated substrates. Effects of hot-pressing, compression, measurement method, and substrate on the through-plane thermal conductivity of the CL are studied. For this purpose, different thicknesses of catalyst are coated on ethylene tetrafluoroethylene (ETFE) and aluminum (Al) substrates by a conventional Mayer bar coater and measured by scanning electron microscopy (SEM). The through-plane thermal conductivity of the CLs is measured by the well-known guarded heat flow (GHF) method as well as a recently developed transient plane source (TPS) method for thin films which modifies the original TPS thin film method. Measurements show that none of the studied factors has any effect on the through-plane thermal conductivity of the CL. GHF measurements of a non-hot-pressed CL on Al yield thermal conductivity of 0.214 ± 0.005 Wṡm-1ṡK-1, and TPS measurements of a hot-pressed CL on ETFE yield thermal conductivity of 0.218 ± 0.005 Wṡm-1ṡK-1.

  19. A combined in situ XAS-XRPD-Raman study of Fischer-Tropsch synthesis over a carbon supported Co catalyst

    DEFF Research Database (Denmark)

    Tsakoumis, Nikolaos E.; Dehghan, Roya; Johnsen, Rune

    2013-01-01

    A cobalt based Fischer-Tropsch synthesis (FTS) catalyst, supported on a carbon nanofibers/carbon felt composite (Co/CNF/CF) was studied in situ at realistic conditions. The catalyst was monitored by Xray absorption spectroscopy (XAS), high-resolution X-ray powder diffraction (HR-XRPD) and Raman...... to reduce further at the induction period of FTS, while crystallite growth is been detected in the same period. At steady state FTS the amount of metallic Co is constant. A change in the volumetric flow towards higher conversions did not affect the degree of reduction or the crystallite size of the catalyst...

  20. Theoretical and experimental study on formation and adsorption of enolic species on Ag-Pd/Al2O3 catalyst.

    Science.gov (United States)

    Gao, Hongwei; He, Hong; Feng, Qingcai; Wang, Jin

    2005-10-01

    The formation and adsorption of enolic species on a palladium promoted Ag/Al2O3 catalyst (denoted Ag-Pd/Al2O3) during the selective catalytic reduction (SCR) of NOx by C3H6 has been studied by means of DRIFTS and density functional calculations. The structure of the enolic species adsorbed on Ag-Pd/Al2O3 catalyst has been established based on the in situ DRIFTS spectra and simulated results. The reaction mechanism from C3H6 to enolic species on Ag-Pd/Al2O3 catalyst was proposed and the hypothesis about the Pd promotion was discussed.

  1. Structural studies on HCN oligomers. [catalysts for prebiotic processes

    Science.gov (United States)

    Ferris, J. P.; Edelson, E. H.; Auyeung, J. M.; Joshi, P. C.

    1981-01-01

    NMR spectral studies on the HCN oligomers suggest the presence of carboxamide and urea groupings. The release of CO2, H2O, HCN, CH3CN, HCONH2 and pyridine on pyrolysis is consistent with the presence of these groupings as well as carboxylic acid groups. No basic primary amine groupings could be detected with fluorescamine. Hydrazinolysis of the HCN oligomers releases 10% of the amino acids normally released by acid hydrolysis. The oligomers give a positive biuret test but this is not due to the presence of peptide bonds. There is no conclusive evidence for the presence of peptide bonds in the HCN oligomers. No diglycine was detected on partial hydrolysis of the HCN oligomers at pH 8.5 suggesting that HCN oligomers were not a source of prebiotic peptides.

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

    Directory of Open Access Journals (Sweden)

    Anna Piskun

    2016-08-01

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

  3. Study of Alginate-Supported Ionic Liquid and Pd Catalysts

    Directory of Open Access Journals (Sweden)

    Eric Guibal

    2012-01-01

    Full Text Available New catalytic materials, based on palladium immobilized in ionic liquid supported on alginate, were elaborated. Alginate was associated with gelatin for the immobilization of ionic liquids (ILs and the binding of palladium. These catalytic materials were designed in the form of highly porous monoliths (HPMs, in order to be used in a column reactor. The catalytic materials were tested for the hydrogenation of 4-nitroaniline (4-NA in the presence of formic acid as hydrogen donor. The different parameters for the elaboration of the catalytic materials were studied and their impact analyzed in terms of microstructures, palladium sorption properties and catalytic performances. The characteristics of the biopolymer (proportion of β-D-mannuronic acid (M and α-L-guluronic acid (G in the biopolymer defined by the M/G ratio, the concentration of the porogen agent, and the type of coagulating agent significantly influenced catalytic performances. The freezing temperature had a significant impact on structural properties, but hardly affected the catalytic rate. Cellulose fibers were incorporated as mechanical strengthener into the catalytic materials, and allowed to enhance mechanical properties and catalytic efficiency but required increasing the amount of hydrogen donor for catalysis.

  4. Kjel-Foss automatic analysis using an antimony-based catalyst: collaborative study.

    Science.gov (United States)

    Bjarnø, O C

    1980-05-01

    Collaborators in 7 Kjel-Foss laboratories and 1 manual Kjeldahl laboratory performed protein determinations on fishmeal: 10 with traditional mercury catalyst and 10 with a new antimony-based catalyst. Repeatability, interlaboratory variation, and variation vs. manual Kjeldahl were equal to or better with the new catalyst than with the mercury catalyst. In addition, 48 different products were analyzed: 5-10 determinations were made on each product with the mercury catalyst and 5-10 were made with the new catalyst. After the Kjel-Foss procedure was modified slightly with higher acid settings, the differences in recovery and repeatability of the 2 procedures were not more than +/- 1%.

  5. Study of catalytic reduction and photodegradation of methylene blue by heterogeneous catalyst

    Science.gov (United States)

    Sohrabnezhad, Sh.

    2011-10-01

    The photocatalytic degradation of methylene blue is investigated in aqueous solution containing CoS/nanoAl-MCM-41 photocatalyst under visible light. The catalyst is characterized by X-ray diffraction (XRD), UV-vis diffused reflectance spectra (UV-vis DRS) and transmission electron microscopy (TEM) techniques. The effect of CoS, nanoAl-MCM-41 support and different wt% of CoS over the support on the photocatalytic degradation and influence of parameters such as CoS loading, catalyst amount, pH and initial concentration of methylene blue on degradation are evaluated. Hypsochromic effects (i.e. blue shifts of spectral bands) resulting from N-demethylation of the dimethylamino group in methylene blue occurs in presence of CoS/nanoAl-MCM-41 under ambient condition. Meanwhile, the bleaching of methylene blue MB, by sulfide ion, in an aqueous solution is studied in the presence nanoAl-MCM-41 catalyst. In the presence of sulfide ions, MB is bleached to its colorless leuco (LMB) and MBH 2+ forms. In an acidified solution (pH bleaching process generates LMB and by changing pH between 2.0 and 7.0 bleaching of MB dye to MBH 2+ form is observed. Using nanoAl-MCM-41 with encapsulated CoS nanoparticles only causes demethylation of MB in aqueous solution.

  6. Structural Modification of Cobalt Catalysts: Effect of Wetting Studied by X-Ray and Infrared Techniques

    Directory of Open Access Journals (Sweden)

    Khodakov A.

    1999-07-01

    Full Text Available The effect of wetting on the structure and localisation of cobalt species on various supports (Al2O3, SiO2, TiO2, HZSM-5 zeolite was studied using X-ray diffraction, Fourier transform infrared spectroscopy with CO as a molecular probe, X-ray photoelectron spectroscopy and extended X-ray absorption fine structure analysis. Aqueous impregnation to incipient wetness of reduced and passivated cobalt catalysts results, even in the absence of any promoter, in a considerable decrease in the concentration of Co crystalline phases and modifies the surface sites. The decrease in the concentration of Co3O4 crystallites was especially pronounced on silica supported catalysts prepared via impregnation of cobalt and on a mixture of Co3O4 and HZSM-5 zeolite. Saturation with water of the passivated Co/SiO2 sample results in an amorphous solid with a local structure close to that of Co2SiO4. For Co/Al2O3 and Co/TiO2 catalysts, the effect of wetting on the concentration of Co3O4 crystalline phase was considerably smaller.

  7. SISGR-Fundamental Experimental and Theoretical Studies on a Novel Family of Oxide Catalyst Supports for Water Electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Kumta, Prashant [University of Pittsburgh

    2014-10-03

    Identification and development of non-noble metal based electro-catalysts or electro-catalysts with significant reduction of expensive noble metal contents (E.g. IrO2, Pt) with comparable electrochemical performance as the standard noble metal/metal oxide for proton exchange membrane (PEM) based water electrolysis would constitute a major breakthrough in the generation of hydrogen by water electrolysis. Accomplishing such a system would not only result reduction of the overall capital costs of PEM based water electrolyzers, but also help attain the targeted hydrogen production cost [< $ 3.0 / gallon gasoline equivalent (gge)] comparable to conventional liquid fuels. In line with these goals, it was demonstrated that fluorine doped IrO2 thin films and nanostructured high surface area powders display remarkably higher electrochemical activity, and comparable durability as pure IrO2 electro-catalyst for the oxygen evolution reaction (OER) in PEM based water electrolysis. Furthermore, corrosion resistant SnO2 and NbO2 support has been doped with F and coupled with IrO2 or RuO2 for use as an OER electro-catalyst. A solid solution of SnO2:F or NbO2:F with only 20 - 30 mol.% IrO2 or RuO2 yielding a rutile structure in the form of thin films and bulk nanoparticles displays similar electrochemical activity and stability as pure IrO2/RuO2. This would lead to more than 70 mol.% reduction in the noble metal oxide content. Novel nanostructured ternary (Ir,Sn,Nb)O2 thin films of different compositions FUNDAMENTAL STUDY OF NANOSTRUCTURED ELECTRO-CATALYSTS WITH REDUCED NOBLE METAL CONTENT FOR PEM BASED WATER ELECTROLYSIS 4 have also been studied. It has been shown that (Ir0.40Sn0.30Nb0.30)O2 shows similar electrochemical activity and enhanced chemical robustness as compared to pure IrO2. F doping of the ternary (Ir,Sn,Nb)O2 catalyst helps in further decreasing the noble metal oxide content of the catalyst. As a result, these reduced noble metal oxide catalyst systems would

  8. Growth Mechanism of Single-Walled Carbon Nanotubes on Iron–Copper Catalyst and Chirality Studies by Electron Diffraction

    DEFF Research Database (Denmark)

    He, Maoshuai; Liu, Bilu; Chernov, Alexander I.

    2012-01-01

    Chiralities of single-walled carbon nanotubes grown on an atomic layer deposition prepared bimetallic FeCu/MgO catalyst were evaluated quantitatively using nanobeam electron diffraction. The results reveal that the growth yields nearly 90% semiconducting tubes, 45% of which are of the (6,5) type....... The growth mechanisms as well as the roles of different components in the catalyst were studied in situ using environmental transmission electron microscopy and infrared spectroscopy. On the basis of the understanding of carbon nanotube growth mechanisms, an MgO-supported FeCu catalyst was prepared...... by impregnation, showing similar catalytic performance as the atomic layer deposition-prepared catalyst, yielding single-walled carbon nanotubes with a similar narrow chirality distribution....

  9. Soybean oil transesterification: Study of using Nb2O5.xH2O as catalyst in biodiesel production

    Directory of Open Access Journals (Sweden)

    Deborah A. dos Santos

    2012-06-01

    Full Text Available Economic and environmental reasons show a trend towards replacing fossil fuels with biofuels such as those from triglycerides. Biodiesel can be obtained from vegetable oils and animal fat through several processes such as transesterification, esterification, usually with methanol, ethanol or through pyrolysis, all of them in the presence of an acid or basis catalyst. The use of solid catalysts in biodiesel production has the following advantages: easy recovery and reuse, thus decreasing process costs and amount of waste generated.1 Some of the problems in the use of solid catalysts are: low concentration of active sites, microporosity, and leaching of active sites.2 Studies aiming at developing methodologies involving hydrated niobium oxide as catalyst in biodiesel production have been carried out by our research group.3,4 Parameters such as the use of assistant solvent to increase the boiling point of the mixture (toluene, ethylene glycol, and DMSO, pre-thermal treatment (calcinations and catalyst molar concentration were initially assessed in esterification, oleic acid, and methanol reactions.  From these studies we could observe that high temperatures and excessive alcohol favor esterification reactions.  The best reaction conditions were then used as models and employed in transesterification reactions of soybean oil.  DMSO (Dimethyl sulfoxide was the solvent used to increase the reaction medium temperature without evaporating all the methanol. Transesterification reactions were carried out with soybean oil (0.5 g, methanol (0.85 g, DMSO (2.50 ml, and hydrated niobium oxide as catalyst in ratios of 20% and 100% (in relation to oil mass.  Catalyst was employed without pretreatment and after pretreatment at 115 °C, 300 °C, and 500 °C. The reactions occurred at 170 °C, under reflux for 48 hours.  A reaction without a catalyst was also carried out. All the reactions have shown conversion using CCD and they have been determined by 1H NMR

  10. Spent fluid catalytic cracking catalyst (FCC) applications in the preparation of hydraulic binders: Pozzolanic properties study

    Science.gov (United States)

    Velazquez Rodriguez, Sergio

    At the present work the replacement of Portland cement in pastes and mortars by spent fluid catalytic cracking catalyst (FCC) is studied. The study has been focused in four physicochemical characterization, hydrated lime/catalyst and cement/catalyst pastes and mortars studies, and environmental impact aspects. The FCC characterization establishes that it is a silicoaluminate, having a mainly amorphous structure, with a great specific surface, and that is necessary its mechanical activation (grinding) to obtain a pozzolanic behaviour material. The reactivity was studied by: thermogravimetry, X ray diffractometry, aqueous media electrical conductivity measurements, Fourier transform infrared spectroscopy, scanning electron microscopy, mechanical strength development evaluation and cementing effectiveness k-factor evaluation. The very high pozzolanic activity of the material has been demonstrated, besides that this reactivity has been superior to others similar products such as the metakaolin. The products formed in the hydration, pozzolanic and hydration catalysis of cement reactions have been studied, comparing the reactivity characteristics with others better known pozzolans. The nature of the reaction products between FCC and hydrated lime is similar to the ones formed by the metakaolin, being fundamentally calcium silicate hydrates and hydrated gehlenite, and their formation allow to obtain microstructures with higher mechanical strength. The possibility of preparation materials containing cement/FCC with improved mechanical strength and drying shrinkage has been demonstrated, compared to homologous materials without ground FCC. The optimal FCC dosage for the lime fixation maximization has been determined, showing a pozzolanic behaviour similar to metakaolin, nevertheless very superior to others studied pozzolans, behaviour that is improved with the aid of certain chemical activators, and with the increasing of the curing temperature. Measurements of electrical

  11. In operando Detection of Three-Way Catalyst Aging by a Microwave-Based Method: Initial Studies

    Directory of Open Access Journals (Sweden)

    Gregor Beulertz

    2015-07-01

    Full Text Available Initial studies on aging detection of three way catalysts with a microwave cavity perturbation method were conducted. Two physico-chemical effects correlate with the aging state. At high temperatures, the resonance frequencies for oxidized catalysts (λ = 1.02 are not influenced by aging, but are significantly affected by aging in the reduced case (λ = 0.98. The catalyst aging state can therefore potentially be inferred from the resonance frequency differences between reduced and oxidized states or from the resonance frequency amplitudes during lambda oscillations. Secondly, adsorbed water at low temperatures strongly affects the resonance frequencies. Light-off experiment studies showed that the resonance frequency depends on the aging state at temperatures below the oxygen storage light-off. These differences were attributed to different water sorption capabilities of differently aged samples due to a surface area decrease with proceeding aging. In addition to the aging state, the water content in the feed gas and the temperature affect the amount of adsorbed water, leading to different integral electrical material properties of the catalyst and changing the resonance properties of the catalyst-filled canning. The classical aging-related properties of the catalyst (oxygen storage capacity, oxygen storage light-off, surface area, agreed very well with data obtained by the microwave-based method.

  12. Utilization of greenhouse gases through dry reforming: screening of nickel-based bimetallic catalysts and kinetic studies.

    Science.gov (United States)

    Fan, Mun-Sing; Abdullah, Ahmad Zuhairi; Bhatia, Subhash

    2011-11-18

    A series of bimetallic catalysts containing nickel supported over MgO-ZrO2 were tested for activity in the dry reforming of carbon dioxide. A nickel-cobalt bimetallic catalyst gave the best performance in terms of conversion and coke resistance from a range of Ni-X bimetallic catalysts, X=Ca, K, Ba, La, and Ce. The nitrogen-adsorption and hydrogen-chemisorption studies showed the Ni-Co bimetallic supported catalyst to have good surface area with high metal dispersion. This contributed to the high catalytic activity, in terms of conversion activity and stability of the catalyst, at an equimolar methane/carbon dioxide feed ratio. The kinetics of methane dry reforming are studied in a fixed-bed reactor over an Ni-Co bimetallic catalyst in the temperature range 700-800 °C by varying the partial pressures of CH4 and CO2. The experimental data were analyzed based on the proposed reaction mechanism using the Langmuir-Hinshelwood kinetic model. The activation energies for methane and carbon dioxide consumption were estimated at 52.9 and 48.1 kJ mol(-1), respectively. The lower value of CO2 activation energy compared to the activation energy of CH4 indicated a higher reaction rate of CO2, which owes to the strong basicity of nanocrystalline support, MgO-ZrO2.

  13. Studies on the behaviour of different spent fluidized-bed catalytic cracking catalysts on Portland cement

    Directory of Open Access Journals (Sweden)

    Soriano, L.

    2009-12-01

    Full Text Available The fluidized-bed catalytic cracking catalyst (FCC it is a residue from the industry of the petroleum that shows a high pozzolanic reactivity and, in cementing matrix, it significantly improves their mechanical behaviour as well as durability. In this research a comparative study on residues of catalyst from different sources has been carried out, in order to know if these residues can be used jointly in an indiscriminate way or, on the contrary, it is necessary to classify them according to their characteristics. Thus, a study on five different FCC residues, supplied from different companies, has been carried out, and their physical-chemical characteristics, pozzolanic reactivity by means of thermogravimetric analysis and the evolution of the mechanical strength of mortars were studied. After analyzing all the aspects, it can be concluded that no significant differences among the different tested catalysts were found.El catalizador de craqueo catalítico (FCC es un residuo de la industria del petróleo que posee una elevada reactividad puzolánica y en matrices cementicias mejora de manera importante los aspectos mecánicos así como de durabilidad. En este trabajo se realiza un estudio comparativo sobre residuos de catalizador de distintos orígenes, para poder conocer si se pueden utilizar conjuntamente de forma indiscriminada o por el contrario hay que catalogarlos según su origen. Para ello, se realizó un estudio sobre cinco residuos de catalizador de craqueo catalítico distintos, suministrados por diferentes empresas y se estudiaron sus características fisicoquímicas, reactividad puzolánica a través de estudios termogravimétricos y la evolución de las resistencias mecánicas en morteros. Tras analizar todos los aspectos se concluye que no existen diferencias significativas entre los distintos catalizadores empleados.

  14. Steam reforming of methanol over oxide decorated nanoporous gold catalysts: a combined in situ FTIR and flow reactor study.

    Science.gov (United States)

    Shi, J; Mahr, C; Murshed, M M; Gesing, T M; Rosenauer, A; Bäumer, M; Wittstock, A

    2017-03-29

    Methanol as a green and renewable resource can be used to generate hydrogen by reforming, i.e., its catalytic oxidation with water. In combination with a fuel cell this hydrogen can be converted into electrical energy, a favorable concept, in particular for mobile applications. Its realization requires the development of novel types of structured catalysts, applicable in small scale reactor designs. Here, three different types of such catalysts were investigated for the steam reforming of methanol (SRM). Oxides such as TiO 2 and CeO 2 and mixtures thereof (Ce 1 Ti 2 O x ) were deposited inside a bulk nanoporous gold (npAu) material using wet chemical impregnation procedures. Transmission electron and scanning electron microscopy reveal oxide nanoparticles (1-2 nm in size) abundantly covering the strongly curved surface of the nanoporous gold host (ligaments and pores on the order of 40 nm in size). These catalysts were investigated in a laboratory scaled flow reactor. First conversion of methanol was detected at 200 °C. The measured turn over frequency at 300 °C of the CeO x /npAu catalyst was 0.06 s -1 . Parallel investigation by in situ infrared spectroscopy (DRIFTS) reveals that the activation of water and the formation of OH ads are the key to the activity/selectivity of the catalysts. While all catalysts generate sufficient OH ads to prevent complete dehydrogenation of methanol to CO, only the most active catalysts (e.g., CeO x /npAu) show direct reaction with formic acid and its decomposition to CO 2 and H 2 . The combination of flow reactor studies and in operando DRIFTS, thus, opens the door to further development of this type of catalyst.

  15. Study on the NO removal efficiency of the lignite pyrolysis coke catalyst by selective catalytic oxidation method

    Science.gov (United States)

    Wen, Xin; Ma, Zhenhua; Zhang, Lei; Sha, Xiangling; He, Huibin; Zeng, Tianyou; Wang, Yusu; Chen, Jihao

    2017-01-01

    Selective catalytic oxidation (SCO) method is commonly used in wet denitration technology; NO after the catalytic oxidation can be removed with SO2 together by wet method. Among the SCO denitration catalysts, pyrolysis coke is favored by the advantages of low cost and high catalytic activity. In this paper, SCO method combined with pyrolysis coke catalyst was used to remove NO from flue gas. The effects of different SCO operating conditions and different pyrolysis coke catalyst made under different process conditions were studied. Besides, the specific surface area of the catalyst and functional groups were analyzed with surface area analyzer and Beohm titration. The results are: (1) The optimum operating conditions of SCO is as follows: the reaction temperature is 150°C and the oxygen content is 6%. (2) The optimum pyrolysis coke catalyst preparation processes are as follows: the pyrolysis final temperature is 750°C, and the heating rate is 44°C / min. (3) The characterization analysis can be obtained: In the denitration reaction, the basic functional groups and the phenolic hydroxyl groups of the catalyst play a major role while the specific surface area not. PMID:28793346

  16. Structural study of radiolytic catalysts Ni-Ce/Al2O3 and Ni-Pt/Al2O3

    Science.gov (United States)

    Seridi, F.; Chettibi, S.; Keghouche, N.; Beaunier, P.; Belloni, J.

    2017-01-01

    Ni-Ce and Ni-Pt bimetallic catalysts supported over α-Al2O3 are synthesized by using co-impregnation method, and then reduced, each via radiolytic process or thermal H2-treatment. For Ni-Ce/Al2O3, the structural study reveals that Ce is alloyed with Ni as Ce2Ni7 nanoparticles in the radiation-reduced catalysts, while it segregates to the surface in the form of CeO2 in the H2-reduced catalysts. For Ni-Pt/Al2O3 radiolytic catalysts, Ni, Pt, NiPt and Ni3Pt nanoparticles, which size is 3.5 nm, are observed. When the radiation-reduced samples are tested in the benzene hydrogenation, they both display high conversion rate. However, the Ni-Pt/Al2O3 is more efficient than Ni-Ce/Al2O3. The performance of the catalysts is correlated with the high dispersion of the metal and the presence of intermetallic Ni-Pt and Ni-Ce phases. It is compared to that of other radiolytic monometallic/oxide catalysts of the literature.

  17. Theoretical study to investigate the impact of plasma parameters on the catalyst nanoparticle growth

    Science.gov (United States)

    Gupta, R.; Sharma, S. C.; Gupta, N.

    2017-05-01

    The plasma kinetics based model is adopted to elucidate the effect of plasma parameters on the nucleation and growth mechanism of catalyst nanoparticle. The present model considers the plasma processing of thin catalyst film, power equalization at the film surface, flux and kinetics of plasma species (electrons, ions, and neutrals). In our investigation, it is found that catalyst nanoparticle diameter decreases with increase in ion number density in plasma. Moreover, it is also found that catalyst film thickness significantly affect the catalyst nanoparticle size i.e., catalyst nanoparticle diameter increases with catalyst film thickness. In addition, it is observed that the substrate temperature increases during the plasma processing and finally achieve saturation. Our theoretical results are in good agreement with the experimental results.

  18. Parametric study of ionomer dispersions in catalyst inks by dynamic light scattering

    Energy Technology Data Exchange (ETDEWEB)

    Le Marquand, P.; Xie, Z.; Peron, J.; Navessin, T.; Holdcroft, S. [National Research Council of Canada, Vancouver, BC (Canada). Inst. for Fuel Cell Innovation

    2009-07-01

    This study investigated the effects of ink formulation and preparation on the particle size distribution (PSD) of proton exchange membrane fuel cell (PEMFC) membrane exchange assemblies (MEA). The physical and structural characteristics of different ink types were evaluated in relation to various deposition methods and MEA microstructure and performance. Model systems of an ionomer and dispersing solvent were investigated. PSDs were measured using a dynamic light scattering instrument with a backscattering angle of 173 degrees. The filtration, ionomer concentration, and solvent proportions of binary dispersants were discussed. Single solvent systems with different structures, functional groups and dielectric strengths were also investigated. PSD analyses of Nafion and SPEEK catalyst inks were also conducted.

  19. (Naphthalene-2,3-diolato-κ2O,O′[tris(pyridin-2-ylmethylamine-κ4N]cobalt(III tetraphenylborate acetone monosolvate hemihydrate

    Directory of Open Access Journals (Sweden)

    Fan Yu

    2012-10-01

    Full Text Available In the title salt, [Co(C10H6O2(C18H18N4](C24H20B·C3H6O·0.5H2O, the CoIII ion in the complex cation is six-coordinated in a rigid octahedral N4O2 geometry. The asymmetric unit contains one complete [Co(C10H6O2(C18H18N4]+ unit, one tetraphenylborate counter-anion and one acetone and one water molecule that is located on an inversion centre. All the features of the CoIII ion are fully consistent with the formulation of the cation as a Co3+–catecholate complex. Variable-temperature magnetic measurements in the region 2–380 K show a obvious diamagnetism over the observed temperature range.

  20. Catalytic and DRIFTS study of the WGS reaction on Pt-based catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Vignatti, Ch.; Avila, M.S.; Apesteguia, C.R.; Garetto, T.F. [Catalysis Science and Engineering Research Group (GICIC), Instituto de Investigaciones en Catalisis y Petroquimica - INCAPE - (UNL-CONICET), Santiago del Estero 2654, 3000 Santa Fe (Argentina)

    2010-07-15

    The water-gas shift (WGS) activity of Pt/SiO{sub 2}, Pt/CeO{sub 2} and Pt/TiO{sub 2} catalysts was studied by in-situ diffuse reflection infrared Fourier transform spectroscopy (DRIFTS). Samples contained a similar amount of Pt, between 0.34 and 0.50%, and were characterized by employing a variety of physical and spectroscopic techniques. The catalyst activities were evaluated through both CO conversion versus temperature and CO conversion versus time tests. The DRIFTS spectra were obtained on stream during the WGS reaction at increasing temperatures, from 303 to 573 K. Reduced ceria was the only active support and promoted the WGS reaction on surface bridging OH groups that react with CO to form formate intermediates. Pt/SiO{sub 2} was more active than CeO{sub 2} and catalyzed the WGS reaction through a monofunctional redox mechanism on metallic Pt sites. The CO conversion turnover rate was more than one order of magnitude greater on Pt/CeO{sub 2} than on Pt/SiO{sub 2} showing that the reaction proceeds faster via a bifunctional metal-support mechanism. Platinum on Pt/CeO{sub 2} increased the concentration of OH groups by increasing the ceria reduction extent and also provided a faster pathway for the formation of formate intermediates in comparison to CeO{sub 2} support. Pt/TiO{sub 2} catalysts were clearly more active than Pt/CeO{sub 2}. The WGS reaction on Pt/TiO{sub 2} was catalyzed via a bifunctional metal-support mechanism, probably involving the activation of CO and water on the metal and the support, respectively. The role of platinum on Pt/TiO{sub 2} was critical for promoting the reduction of Ti{sup 4+} ions to Ti{sup 3+} which creates oxygen vacancies in the support to efficiently activate water. (author)

  1. System Identification for Experimental Study for Polymerization Catalyst Reaction in Fluidized Bed

    Directory of Open Access Journals (Sweden)

    Ahmmed Saadi Ibrehem

    2011-11-01

    Full Text Available In this work, system identification method is used to capture the reactor characteristics of production rate of polyethylene (PE based on published experimental data. The identification method is used to measure the percentage effect on the production rate of PE by measuring the effect of input factors of temperature of reaction, hydrogen concentration, and [Al]/[Ti] molar catalyst ratio. Temperature of reaction has big effects equal 52.4 % on the output of the system and 47.6 % on interaction of the system's parameters compare to other two factors. Also, hydrogen concentration has big effect equal 45.66 % on the output of the system and 14.7 % on interaction of the system's parameters. [Al]/[Ti] molar catalyst ratio has big effect on interaction of the system equal 28.6 and 1.94 % on the output of the system but less than the reaction temperature and hydrogen concentration. All these results depend on experiment results and these results are very important in industrial plants. ©2011 BCREC UNDIP. All rights reserved(Received: 13rd May 2011; Revised: 27th July 2011; Accepted: 22th September 2011[How to Cite: Ahmmed S. Ibrehem. (2011. System Identification for Experimental Study for Polymerization Catalyst Reaction in Fluidized Bed. Bulletin of Chemical Reaction Engineering & Catalysis, 6 (2: 137-146. doi:10.9767/bcrec.6.2.874.137-146][How to Link / DOI: http://dx,doi.org/10.9767/bcrec.6.2.874.137-146 || or local:  http://ejournal.undip.ac.id/index.php/bcrec/article/view/874 ] | View in 

  2. Crystal structure of di-μ-aqua-μ-(pyrazine N,N′-dioxide-κ2O:O-bis(diaquasodium tetraphenylborate dihydrate pyrazine N,N′-dioxide monosolvate

    Directory of Open Access Journals (Sweden)

    Elaine P. Boron

    2015-12-01

    Full Text Available The search for novel lanthanide coordination networks using pyrazine N,N′-dioxide (pzdo, C4H4N2O2 as a structure-directing unit, led to the synthesis and the structure determination of the title compound, [Na2(C4H4N2O2(H2O6][B(C6H54]2·C4H4N2O2·2H2O. The crystal structure is comprised of discrete [{Na(H2O2}2(μ-H2O2(μ-pzdo]2+ cations and tetraphenylborate anions, as well as pzdo and H2O solvent molecules. The dinuclear cation is located about a twofold rotation axis, and the symmetry-related NaI atoms display a distorted square-pyramidal coordination sphere defined by two O atoms of terminal water ligands, two O atoms of bridging water ligands and one O atom of a bridging pzdo ligand. In the crystal, O—H...O hydrogen bonds link the dinuclear cation and solvent pzdo molecules (point-group symmetry -1 into rectangular grid-like layers parallel to the bc plane. Additional C—H...O, O—H...O, C—H...π and O—H...π interactions link the anion and solvent water molecules to the layers. The layers are further linked into a three-dimensional network through a combination of C—H...π and O—H...π hydrogen bonds involving the tetraphenylborate anion.

  3. Study of the performance of vanadium based catalysts prepared by grafting in the oxidative dehydrogenation of propane

    Energy Technology Data Exchange (ETDEWEB)

    Santacesaria, E.; Carotenuto, G.; Tesser, R.; Di Serio, M. [Naples Univ. (Italy). Dept. of Chemistry

    2011-07-01

    The oxidative dehydrogenation (ODH) of propane has been investigated by using many different vanadia based catalysts, prepared by grafting technique and containing variable amounts of active phase supported on SiO{sub 2} previously coated, by grafting in three different steps, with multilayer of TiO{sub 2}. A depth catalytic screening, conducted in a temperature range of 400-600 C, at atmospheric pressure and in a range of residence time W/F=0.08-0.33 ghmol{sub -1}, has shown that the vanadium oxide catalysts on TiO{sub 2}-SiO{sub 2} support, prepared by grafting have good performances in the ODH of propane. In particular, a preliminary study has demonstrated that higher selectivities can be obtained employing catalysts having a well dispersed active phase that can be achieved with a V{sub 2}O{sub 5} content lower than 10%{sub w}t. It is well known that, in the case of redox catalysts, an increase of the selectivity can be achieved not only by using an adequate catalytic system but also via engineering routes like decoupling catalytic steps of reduction and re-oxidation. In fact it has been observed that by operating in dehydrogenating mode, on the same catalysts, a higher selectivity is obtained although the catalyst is poisoned by the formation of coke on the surface. As consequence of the results obtained in dehydrogenation, in this work has been explored the possibility to feed low amounts of oxygen, below the stoichiometric level with the aim to keep clean the surface from coke but maintaining high the selectivity, because, dehydrogenation reaction prevails. In this work, the behavior of catalysts containing different amounts of V2O5 has been studied in the propane-propene reaction by using different ratios C{sub 3}H{sub 8}/O{sub 2} included in the range 0-2. (orig.)

  4. 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

  5. Studies on the oxygen reduction catalyst for zinc-air battery electrode

    Science.gov (United States)

    Wang, Xianyou; Sebastian, P. J.; Smit, Mascha A.; Yang, Hongping; Gamboa, S. A.

    In this paper, perovskite type La 0.6Ca 0.4CoO 3 as a catalyst of oxygen reduction was prepared, and the structure and performance of the catalysts was examined by means of IR, X-ray diffraction (XRD), and thermogravimetric (TG). Mixed catalysts doped, some metal oxides were put also used. The cathodic polarization curves for oxygen reduction on various catalytic electrodes were measured by linear sweep voltammetry (LSV). A Zn-air battery was made with various catalysts for oxygen reduction, and the performance of the battery was measured with a BS-9300SM rechargeable battery charge/discharge device. The results showed that the perovskite type catalyst (La 0.6Ca 0.4CoO 3) doped with metal oxide is an excellent catalyst for the zinc-air battery, and can effectively stimulate the reduction of oxygen and improve the properties of zinc-air batteries, such as discharge capacity, etc.

  6. Kinetic and spectroscopic study of catalysts for water-gas shift and nitrogen oxide removal

    Science.gov (United States)

    Kispersky, Vincent Frederick

    Nitrogen oxides (NOx) are formed in high temperature combustion processes such as in power generation and motor vehicles. Increasingly stringent regulation of these harmful emissions continues to drive interest in developing, understanding and studying new catalytic formulations for exhaust aftertreatment. For mobile sources, predominantly heavy duty diesel engines, selective catalytic reduction (SCR) with NH3 has become the principal means of NO x abatement. An alternative technology developed, but now surpassed by SCR, is NOx Storage Reduction (NSR) catalysis. Both technologies have been studied in our laboratory and are the basis for this dissertation. We studied seven different lean NOx trap (LNT) monolith formulations for NSR ranging from 0.6 to 6.2 wt.% Pt and 4 to 20 wt.% Ba loadings on γ-Al 2O3. The noble metal component of a LNT oxidizes NO to NO 2 aiding in the storage of NO2 on the alkaline earth component. Before the storage component saturates, a reductant such as H2 is introduced into the vehicular exhaust and the stored NOx is released and reduced to N2. Once the storage component is free of NOx, reductant flow is ceased and storage is begun anew. Our research focused on understanding the effects that CO2 and H2O have on the storage capacity of the LNT over short as well as extended periods of time. We found that for high Ba loadings, CO 2 had a consistently detrimental effect on the fast NOx storage capacity (NSC), defined as the amount of NOx the catalyst can store before 1% of the inlet NOx is measured in the reactor outlet. Over long NOx storage periods, CO2 continued to inhibit storage compared to the same catalyst in CO2 free conditions. On low loadings of Ba, however, the inhibition of CO2 was significantly reduced. We found that the loading dependent characteristics of the Ba phase affected the way in which CO2 adsorbed on the storage component, which greatly affected the stability of the species on lower Ba loadings. The less stable

  7. Density functional theory study for the enhanced sulfur tolerance of Ni catalysts by surface alloying

    Science.gov (United States)

    Hwang, Bohyun; Kwon, Hyunguk; Ko, Jeonghyun; Kim, Byung-Kook; Han, Jeong Woo

    2018-01-01

    Sulfur compounds in fuels deactivate the surface of anode materials in solid oxide fuel cells (SOFCs), which adversely affect the long-term durability. To solve this issue, it is important to design new SOFC anode materials with high sulfur tolerance. Unfortunately, it is difficult to completely replace the traditional Ni anode owing to its outstanding reactivity with low cost. As an alternative, alloying Ni with transition metals is a practical strategy to enhance the sulfur resistance while taking advantage of Ni metal. Therefore, in this study, we examined the effects of transition metal (Cu, Rh, Pd, Ag, Pt, and Au) doping into a Ni catalyst on not only the adsorption of H2S, HS, S, and H but also H2S decomposition using density functional theory (DFT) calculations. The dopant metals were selected rationally by considering the stability of the Ni-based binary alloys. The interactions between sulfur atoms produced by H2S dissociation and the surface are weakened by the dopant metals at the topmost layer. In addition, the findings show that H2S dissociation can be suppressed by doping transition metals. It turns out that these effects are maximized in the Au-doped Ni catalyst. Our DFT results will provide useful insights into the design of sulfur-tolerant SOFC anode materials.

  8. Platinum supported catalysts for carbon monoxide preferential oxidation: Study of support influence

    Energy Technology Data Exchange (ETDEWEB)

    Padilla, R.; Rodriguez, L.; Serrano-Lotina, A.; Daza, L. [Instituto de Catalisis y Petroleoquimica (CSIC), C/Marie Curie 2, Campus Cantoblanco, 28049 Madrid (Spain); Benito, M. [Instituto de Catalisis y Petroleoquimica (CSIC), C/Marie Curie 2, Campus Cantoblanco, 28049 Madrid (Spain); Centro de Investigaciones Energeticas Medioambientales y Tecnologicas (CIEMAT), Av. Complutense 22, 28040 Madrid (Spain)

    2009-07-01

    The aim of this work is to study the influence of the addition of different oxides to an alumina support, on surface acidity and platinum reducibility in platinum-based catalysts, as well as their effect on the activity and selectivity in CO preferential oxidation, in presence of hydrogen. A correlation between surface acidity and acid strength of surface sites and metal reducibility was obtained, being Pt-support interaction a function of the acid sites concentration under a particular temperature range. In platinum supported on alumina catalysts, CO oxidation follows a Langmuir-Hinshelwood mechanism, where O{sub 2} and CO compete in the adsorption on the same type of active sites. It is noteworthy that the addition of La{sub 2}O{sub 3} modifies the reaction mechanism. In this case, CO is not only adsorbed on the Pt active sites but also on La{sub 2}O{sub 3}, forming bridge bonded carbonates which leads to high reactivity at low temperatures. An increase on temperature produces CO desorption from Pt surface sites and favours oxygen adsorption producing CO{sub 2}. CO oxidation with surface hydroxyl groups was activated producing simultaneously CO{sub 2} and H{sub 2}. (author)

  9. HZSM-5 CATALYST FOR CRACKING PALM OIL TO BIODIESEL: A COMPARATIVE STUDY WITH AND WITHOUT PT AND PD IMPREGNATION

    Directory of Open Access Journals (Sweden)

    Agus Budianto

    2014-05-01

    Full Text Available The Needs of healthy environment and green energy poses a great demand for alternative energy. Biofuel is one of the alternative energy products that are environmentally friendly. Biofuel can be made from plant oils, especially palm oil. Cracking of palm oil into biofuel is constrained by the availability of catalysts. Moreover the available catalyst still gives a low yield. This research aims to study the effect of Pt and Pd impregnation into HZSM-5 catalyst on the catalytic properties. Another aim is to obtain the operating conditions of the catalytic cracking process of palm oil into biofuel which gives the highest yield and selectivity, especially for biodiesel and biogasoline fractions. Catalytic cracking process was carried out in a micro fixed bed reactor with diameter of 1 cm and length of 16 cm. The reactor was filled with a catalyst. The results of the study successfully prove that Pt and Pd impregnated into HZSM-5 catalyst can increase the yield and selectivity of biodiesel. Pd and Pt are highly recommended to increase the yield and selectivity of biodiesel.

  10. Direct vs. indirect pathway for nitrobenzene reduction reaction on a Ni catalyst surface: a density functional study.

    Science.gov (United States)

    Mahata, Arup; Rai, Rohit K; Choudhuri, Indrani; Singh, Sanjay K; Pathak, Biswarup

    2014-12-21

    Density functional theory (DFT) calculations are performed to understand and address the previous experimental results that showed the reduction of nitrobenzene to aniline prefers direct over indirect reaction pathways irrespective of the catalyst surface. Nitrobenzene to aniline conversion occurs via the hydroxyl amine intermediate (direct pathway) or via the azoxybenzene intermediate (indirect pathway). Through our computational study we calculated the spin polarized and dispersion corrected reaction energies and activation barriers corresponding to various reaction pathways for the reduction of nitrobenzene to aniline over a Ni catalyst surface. The adsorption behaviour of the substrate, nitrobenzene, on the catalyst surface was also considered and the energetically most preferable structural orientation was elucidated. Our study indicates that the parallel adsorption behaviour of the molecules over a catalyst surface is preferable over vertical adsorption behaviour. Based on the reaction energies and activation barrier of the various elementary steps involved in direct or indirect reaction pathways, we find that the direct reduction pathway of nitrobenzene over the Ni(111) catalyst surface is more favourable than the indirect reaction pathway.

  11. Degradation Study by Start-Up/Shut-Down Cycling of Superhydrophobic Electrosprayed Catalyst Layers Using a Localized Reference Electrode Technique.

    Science.gov (United States)

    Ferreira-Aparicio, Paloma; Chaparro, Antonio M; Folgado, M Antonia; Conde, Julio J; Brightman, Edward; Hinds, Gareth

    2017-03-29

    Degradation of a polymer electrolyte membrane fuel cell (PEMFC) with electrosprayed cathode catalyst layers is investigated during cyclic start-up and shut-down events. The study is carried out within a single cell incorporating an array of reference electrodes that enables measurement of cell current as a function of local cathode potential (localized polarization curves). Accelerated degradation of the cell by start-up/shut-down cycling gives rise to inhomogeneous performance loss, which is more severe close to the gas outlet and occurs predominantly during start-up. The degradation consists primarily of loss of cathode catalyst activity and increase in cell internal resistance, which is attributed to carbon corrosion and Pt aggregation in both anode and cathode. Cells with an electrosprayed cathode catalyst layer show lower degradation rates during the first 100 cycles, compared with those of a conventional gas diffusion electrode. This difference in behavior is attributed to the high hydrophobicity of the electrosprayed catalyst layer microstructure, which retards the kinetics of corrosion of the carbon support. In the long term, however, the degradation rate is dominated by the Pt/C ratio in the cathode catalyst layer.

  12. Deactivation Studies of Rh/Ce0.8Zr0.2O2 Catalysts in Low Temperature Ethanol Steam Reforming

    Energy Technology Data Exchange (ETDEWEB)

    Platon, Alex; Roh, Hyun-Seog; King, David L.; Wang, Yong

    2007-10-30

    Rapid deactivation of Rh/Ce0.8Zr0.2O2 catalysts in low temperature ethanol steam reforming was studied. A significant build-up of carbonaceous intermediate, instead of carbon deposit, was observed at a lower reaction temperature which was attributed to the rapid catalyst deactivation. Co-feed experiments indicated that acetone and ethylene caused more severe catalyst deactivation than other oxygenates such as acidic acid and acetaldehyde.

  13. Transient studies on the role of oxygen activation in the partial oxidation of methane over ZrO2-based catalysts

    NARCIS (Netherlands)

    Zhu, J. J.; Van Ommen, J. G.; Lefferts, L.

    2004-01-01

    CPOM over ZrO2-based oxide catalysts was studied by transient experiments. The oxidation products, i.e., CO, CO2, H2O, and H2, did not contain any 18O, after pulsing a mixture of CH4 and 18O2 (2:1) over YSZ catalysts at 500°-900°C. Thus, CH4 was oxidized by lattice oxygen of the catalysts. The

  14. Studying PW-Amberlite catalyst deactivation in limonene epoxidation by hydrogen peroxide

    Directory of Open Access Journals (Sweden)

    Rolando Barrera Zapata

    2010-07-01

    95% and 97% when ethanol or acetone were used as washing solvents, respectively. Leaching tests showed that the reaction did not continue when the catalyst was removed from the reaction mixture, confirming the absence of leaching during the catalyst’s active phase. FTIR analysis revealed that the characteristic species of the phosphotungstate complex did not vary with successive reusing of the catalyst.

  15. Studies on the deactivation of NOx storage-reduction catalysts by sulfur dioxide

    NARCIS (Netherlands)

    Sedlmair, C.; Seshan, Kulathuiyer; Jentys, A.; Lercher, J.A.

    2002-01-01

    The interaction of sulfur dioxide with a commercial NOx storage-reduction catalyst (NSR) has been investigated using in situ IR and X-ray absorption spectroscopy. Two pathways of catalyst deactivation by SO2 were identified. Under lean conditions (exposure to SO2 and O2) at 350 °C the storage

  16. In-situ Spectroscopic Studies and Modelling of Crystallization Processes of Sulphuric Acid Catalysts

    DEFF Research Database (Denmark)

    Oehlers, C.; Fehrmann, Rasmus; Masters, Stephen Grenville

    1996-01-01

    Deactivation of commercial and prototype sulphuric acid catalysts has been investigated in-situ by ESR spectroscopy. The influence of support pore structure,and the chemical composition of the catalyst and the gas phase was dicussed.A statistical lattice model was applied to describe...

  17. Catalyst Deactivation 2001

    Energy Technology Data Exchange (ETDEWEB)

    Spivey, J.J. (ed.); Roberts, G.W. (ed.) [Department of Chemical Engineering, 2401 Stinson Avenue, Riddick Engineering Labs, NC State University, Box 7905, Raleigh, NC 27695 (United States); Davis, B.H. (ed.) [University of Kentucky, Centre for Applied Energy Research, 2540 Research Park Drive, Lexington, KY 40511-8433 (United States)

    2001-10-01

    Selected Papers: Maxted Award Lecture. Whisker carbon revisited (J.R. Rostrup-Nielsen, J Sehested). Carbon Deposition. Various forms of the carbonaceous deposit on the model cobalt catalyst studied in hydrogenation of ethylene (J. Lojewska). Hydrodechlorination of 1,2-dichloropropane over Pt-Cu/C catalysts: coke formation determined by a novel technique-TEOM (Weidung. Zhu et al.). Characterization of structure and combustion behavior of the coke formed on a hydroisomerization catalyst (Jin-an Wang et al.). The effects of pore structure on catalyst deactivation by coke formation (L.D.T. Camara et al.). Coke deactivation of acid sites on ZSM-5 zeolite (G.V. Echevsky et al.). Characterization of the Working Catalyst. Deactivation of a zirconia supported chromia aromatization catalyst investigated by in-situ H-D tracer experiments (H. Ehwald et al.). Deactivation/Regeneration in Environmental Processes. Study of the sintering of a DeNOx commercial catalyst (I. Nova et al.). Deactivation of chromium oxide catalyst for the removal of perchloroethylene (PCE) (Sung Dae Yim et al.). Deactivation/Regeneration in Industrial Processes. Deactivation of Pd-based combustion catalysts supported on modified alumina (P.O. Thevenin et al.). Selective acid-base poisoning on bifunctional alkylation reaction (A. Borgna et al.). Processes occurring during deactivation/regeneration of a vanadia/alumina catalyst under propane dehydrogenation conditions (S David Jackson et al.). Regeneration of supported palladium catalyst for selective hydrogenation of acetylene (L.O. Almanza, O.I. Martinez). Quinone mediated stabilization of a palladium catalyst for the synthesis of hydrogen peroxide from carbon monoxide, water and oxygen (D. Bianchi et al.). Metals on a novel USY zeolite after hydrothermal aging (Huiping Tian et al.). General Papers. Partial oxidation of toluene to benzaldehyde over vanadium antimonate catalysts doped with titanium: The influence (S. Larrondo et al.). Deactivation and

  18. Synthesis and study of Pt(Pd)-containing WO3/ZrO2 catalysts for isomerization of n-heptane

    Science.gov (United States)

    Shkurenok, V. A.; Smolikov, M. D.; Yablokova, S. S.; Kir'yanov, D. I.; Kayumova, T. R.; Muromtsev, I. V.; Belyi A., S.

    2017-08-01

    The effect of zirconia precursor in Pt-containing WO3/ZrO2 catalysts on isomerization of n-heptane was studied. Samples synthesized with zirconium sulfate as a ZrO2 precursor were shown to be more active in comparison with those synthesized from zirconium oxychloride. The enhanced activity of samples synthesized from zirconium sulfate is caused by a residual (1-1.3 wt. %) content of sulfate ions in the catalysts, which increases the catalyst acidity; as a result, the samples synthesized with zirconium oxychloride as a ZrO2 precursor are more selective. Characteristics of WO3/ZrO2 catalysts containing Pt or Pd as a metallic component were compared in n-heptane isomerization. The use of Pd as a hydrogenating component of tungstated zirconia catalysts was shown to improve the performance of n-heptane isomerization in comparison with the catalysts where the metallic component was represented by Pt.

  19. Studies on preparation and characterization of Fe/TiO2 catalyst in photocatalysis applications

    Science.gov (United States)

    Kruanetr, Senee; Wanchanthuek, Ratchaneekorn

    2017-07-01

    A Fe/TiO2 photocatalyst was synthesized and used as the catalyst in paraquat degradation as a test reaction to examine the photo-properties. The TEM, XRD, FTIR, UV-vis diffuse reflectance spectrometer, XPS and BET surface area analysis methods were used as the characterization techniques to investigate the physical and chemical properties of the prepared catalyst. Moreover, some of the preparation parameters, such as the preparation method, the content of Fe loading, thermal treatment and source of light irradiation, were also examined. According to the characterization and the expressed catalytic activity, it was found that the factor that significantly responded to the catalyst activity was the -OH surface species on the catalyst surface. Moreover, the lower band gap energy of the Fe/TiO2 catalyst was also an important parameter that gave high catalytic properties because of the higher light adsorption. The preparation scheme and the photodegradation mechanism were proposed.

  20. Studies of long-life pulsed CO2 laser with Pt/SnO2 catalyst

    Science.gov (United States)

    Sidney, Barry D.

    1987-01-01

    Closed-cycle CO2 laser testing with and without a catalyst and with and without CO addition indicate that a catalyst is necessary for long-term operation. Initial results indicate that CO addition with a catalyst may prove optimal, but a precise gas mix has not yet been determined. A long-term run of 10 to the 6th power pulses using 1.3% added CO and a 2% Pt on SnO2 catalyst yields an efficiency of about 95% of open-cycle steady-state power. A simple mathematical analysis yields results which may be sufficient for determining optimum running conditions. Future plans call for testing various catalysts in the laser and longer tests, 10 to the 7th power pulses. A Gas Chromatograph will be installed to measure gas species concentration and the analysis will be slightly modified to include neglected but possibly important parameters.

  1. Infrared Photodissociation Cluster Studies on CO_{2} Interaction with Titanium Oxide Catalyst Models

    Science.gov (United States)

    Dodson, Leah G.; Thompson, Michael C.; Weber, J. Mathias

    2017-06-01

    Titanium oxide catalysts are some of the most promising photocatalyst candidates for renewable energy storage applications via production of solar fuels. To contribute to a molecular-level understanding of the interaction of CO_{2} with titanium oxide, we turn to cluster models in order to circumvent the challenges posed by speciation in the condensed phase. In this work, we use infrared photodissociation spectroscopy (950-2400 cm^{-1}) in concert with density functional theory calculations to identify and characterize [TiO_{x}(CO_{2})_{y}]^{-} (x = 1-3, y = 3-7) clusters. We use these model systems to study the interaction of CO_{2} with TiO, TiO_{2}, and TiO_{3}, and we find that each species exhibits unique infrared signatures and binding motifs. We will discuss the structures of these cluster ions, and how the coordination of the titanium atom plays a role in reduction of CO_{2}.

  2. Kinetic Studies of Oxidative Coupling of Methane Reaction on Model Catalysts

    KAUST Repository

    Khan, Abdulaziz M.

    2016-04-26

    With the increasing production of natural gas as a result of the advancement in the technology, methane conversion to more valuable products has become a must. One of the most attractive processes which allow the utilization of the world’s most abundant hydrocarbon is the oxidative coupling. The main advantage of this process is the ability of converting methane into higher paraffins and olefins (primarily C2) in a direct way using a single reactor. Nevertheless, low C2+ yields have prevented the process to be commercialized despite the fact that great number of attempts to prepare catalysts were conducted so that it can be economically viable. Due to these limitations, understanding the mechanism and kinetics of the reaction can be utilized in improving the catalysts’ performance. The reaction involves the formation of methyl radicals that undergo gas-phase radical reactions. CH4 activation is believed to be done the surface oxygen species. However, recent studies showed that, in addition to the surface oxygen mediated pathway, an OH radical mediated pathway have a large contribution on the CH4 activation. The experiments of Li/MgO, Sr/La2O3 and NaWO4/SiO2 catalysts revealed variation of behavior in activity and selectivity. In addition, water effect analysis showed that Li/MgO deactivate at the presence of water due to sintering phenomena and the loss of active sites. On the other hand, negative effect on the C2 yield and CH4 conversion rate was observed with Sr/La2O3 with increasing the water partial pressure. Na2WO4/SiO2 showed a positive behavior with water in terms of CH4 conversion and C2 yield. In addition, the increment in CH4 conversion rate was found to be proportional with PO2 ¼ PH2O ½ which is consistent with the formation of OH radicals and the OH-mediated pathway. Experiments of using ring-dye laser, which is used to detect OH in combustion experiments, were tried in order to detect OH radicals in the gas-phase of the catalyst. Nevertheless

  3. Study of PtNi/C catalyst for direct ethanol fuel cell; Estudo do catalisador PtNi/C para celula a combustivel de etanol direto

    Energy Technology Data Exchange (ETDEWEB)

    Moraes, L.P.R. de; Silva, E.L. da; Amico, S.C.; Malfatti, C.F., E-mail: eticiaprm@gmail.com [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil)

    2014-07-01

    In this work, PtNi binary catalyst and pure platin catalyst were synthesized by the impregnation-reduction method, using Vulcan XC72R as support, for direct ethanol fuel cells. The composition and structure of the catalysts were analyzed by X-ray diffraction, the electrochemical behavior was evaluated by cyclic voltammetry and morphology of the catalysts was studied by high-resolution transmission electron microscopy. The results showed that the addition of Ni to Pt led to the contraction of the crystal lattice, increased the catalytic activity compared to pure Pt and initiated the electrooxidation of ethanol at lower potential. (author)

  4. A comparative study of n-hexane isomerization over solid acids catalysts: Sulfated and phosphated zirconia

    Directory of Open Access Journals (Sweden)

    Stojkovic N.

    2012-01-01

    Full Text Available Two series of zirconia based catalysts promoted with either sulfates or phosphates were prepared, calcined at different temperatures (600 and 700°C and evaluated for the n-hexane isomerization reaction. The catalysts with different concentrations of sulfates or phosphates (4 or 10 wt. % were characterized by BET, XRD, SEM methods, and total acidity was evaluated by using the Hammett indicators. Their final catalytic performances were correlated with their physical-chemical properties (surface, structural, textural and morphological. It was found that sulfated zirconia catalyst calcined at lower temperature showed the highest initial activity of all tested catalysts as the result of favorable total acidity, mesopore texture and structural properties. Somewhat lower activity of the sulfated catalyst calcined at higher temperature is related to the content of acid groups partially removed during thermal treatment, thus, lower total acidity, and also to less favorable textural and structural features. Negligible activity of phosphated zirconia catalysts is connected with low total acidity despite the positive status of particular property showing the complexity of the active phase/site formation in the catalyst.

  5. STUDY OF EPOXIDE DECYCLISATION OF CARYOPHYLENE OXIDE WITH SYNTHETIC ZEOLITE AS CATALYSTS

    Directory of Open Access Journals (Sweden)

    Winarto Haryadi

    2010-06-01

    Full Text Available The reaction of epoxide ring opening of caryophillene oxide has been done using zeolite H-Y, H-sodalit, and H-ZSM-5 as catalysts. The reactions were done in two types, there were in dioxane solvent at temperature of 110 oC and without solvent at temperature of 175 oC. The catalyst weight was 10 % from caryophillene oxide weight, and the time of reaction was four hours. The product of reaction was analyzed using GC, FTIR, and GC-MS. The reactions of caryophillene oxide in dioxane solvent with the three kinds of zeolites did not give any targeted product. Whereas, the reactions without solvent gave three main products, there was one compound with one group of secondary hidroxyl (secondary alcohol, and two compounds of ketone from caryophillene. The reaction product of caryophillene oxide obtained without using solvent with the three type of catalysts were then compared. Conversion of three main products produced by H-ZSM-5 catalyst, H-sodalit catalyst and H-Y catalyst were 82.11 %, 54.92 % and 38.53 % respectively. For that reason, the transformation of caryophillene oxide using H-ZSM-5 catalyst was considered to be the best selective product. The alcohol product was resulted from reaction between caryophillene oxide and Bronsted acid, and  the ketone products was resulted from the reaction with Lewis acid in zeolite.   Keywords: Epoxide ring opening, HY, H-sodalit and HZSM-5

  6. Bimetallic Catalysts and Platinum Surfaces Studied by X-ray Absorption Spectroscopy and Scanning Tunnelling Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Roenning, Magnus

    2000-07-01

    Bimetallic catalyst systems used in Fischer-Tropsch synthesis (Co-Re/Al{sub 2}O{sub 3}) and in the naphtha reforming process (Pt-Re/Al{sub 2}O{sub 3}) have been studied in situ using X-ray absorption spectroscopy (EXAFS). Additionally, the adsorption of ethene on platinum single crystal surfaces has been investigated using scanning tunnelling microscopy. In situ EXAFS at the cobalt K absorption edge have been carried out at 450{sup o}C on the hydrogen reduction of a rhenium-promoted Co{sub 3}O{sub 4}/Al{sub 2}O{sub 3} catalyst. Reductions carried out using 100% hydrogen and 5% hydrogen in helium gave different results. Whereas the reduction using dilute hydrogen leads to bulk-like metallic cobalt particles (hcp or fcc), reaction with pure hydrogen yields a more dispersed system with smaller cobalt metal particles (< 40 A). The results are rationalised in terms of different degrees of reoxidation of cobalt by the higher and lower concentrations of water generated during the reduction of cobalt oxide by 100% and 5% hydrogen, respectively. Additionally, in both reduction protocols a small fraction (3 -4 wt%) of the cobalt content is randomly dispersed over the tetrahedral vacancies of the alumina support. This dispersion occurs during reduction and not calcination. The cobalt in these sites cannot be reduced at 450 {sup o}C. The local environments about the rhenium atoms in Co-Re/{gamma}-A1{sub 2}O{sub 3} catalyst after different reduction periods have been studied by X-ray absorption spectroscopy. A bimetallic catalyst containing 4.6 wt% cobalt and 2 wt% rhenium has been compared with a corresponding monometallic sample with 2 wt% rhenium on the same support. The rhenium L{sub III} EXAFS analysis shows that bimetallic particles are formed after reduction at 450{sup o}C with the average particle size being 10-15 A. Rhenium is shown to be reduced at a later stage than cobalt. The fraction of cobalt atoms entering the support obstructs the access to the support for the

  7. Plasma-catalyst interaction studied in a single pellet DBD reactor: dielectric constant effect on plasma dynamics

    NARCIS (Netherlands)

    Butterworth, T.; Allen, R. W. K.

    2017-01-01

    A novel single dielectric pellet DBD that is designed to facilitate studying the interaction between plasmas and catalysts is presented. The influence of material dielectric constant on plasma dynamics across a range of applied voltages is determined through the use of electrical characterisation

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

    NARCIS (Netherlands)

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

    2016-01-01

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

  9. STUDY OF THE EFFECT OF CHLORINE ADDITION ON MERCURY OXIDATION BY SCR CATALYST UNDER SIMULATED SUBBITUMINOUS COAL FLUE GAS

    Science.gov (United States)

    An entrained flow reactor is used to study the effect of addition of chlorine-containing species on the oxidation of elemental mercury (Hgo)by a selective catalytic reduction (SCR) catalyst in simulated subbituminous coal combustion flue gas. The combustion flue gas was doped wit...

  10. A Study of Iron-Nitrogen-Carbon Fuel Cell Catalysts: Chemistry - Nanostructure - Performance

    Science.gov (United States)

    Workman, Michael J., Jr.

    Fuel cells have the potential to be a pollution-free, low-cost, and energy efficient alternative to the internal combustion engine for transportation and small-scale stationary power applications. The current state of fuel cell technology has already achieved two of these three lofty goals. The remaining barrier to wide-scale deployment is the high cost, which is primarily caused by dependence on large amounts of platinum to catalyze the energy conversion reactions. To overcome this barrier and facilitate the integration of fuel cells into mainstream applications, research into a new class of catalyst materials that do not require platinum is needed. There has been a significant amount of research effort directed toward the development of platinum-group metal free (PGM-free) catalysts, yet there is a lack of consensus on both the engineering parameters necessary to improve the technology and the fundamental science that would facilitate rational design. I have engaged in research on PGM-free catalysts based on inexpensive and abundant reagents, specifically: nicarbazin and iron. Catalysts made from these precursors have previously proven to be among the best PGM-free catalysts, but their continued advancement suffered from the same lack of understanding that besets all catalysts in this class. The work I have performed address both engineering concerns and fundamental underlying principles. I present results demonstrating correlations between physical structure, chemical speciation, and synthesis parameters, as well as addressing active site chemistry and likely locations. My research presented herein introduces new morphology analysis techniques and elucidates several key structure-to-property characteristics of catalysts derived from iron and nicarbazin. I discuss the development and application of a new length-scale specific surface analysis technique that allows for analysis of well-defined size ranges from a few nm to several microns. The existing technique of

  11. DESTRUCTION OF TETRAPHENYLBORATE IN TANK 48H USING WET AIR OXIDATION BATCH BENCH SCALE AUTOCLAVE TESTING WITH ACTUAL RADIOACTIVE TANK 48H WASTE

    Energy Technology Data Exchange (ETDEWEB)

    Adu-Wusu, K; Paul Burket, P

    2009-03-31

    Wet Air Oxidation (WAO) is one of the two technologies being considered for the destruction of Tetraphenylborate (TPB) in Tank 48H. Batch bench-scale autoclave testing with radioactive (actual) Tank 48H waste is among the tests required in the WAO Technology Maturation Plan. The goal of the autoclave testing is to validate that the simulant being used for extensive WAO vendor testing adequately represents the Tank 48H waste. The test objective was to demonstrate comparable test results when running simulated waste and real waste under similar test conditions. Specifically: (1) Confirm the TPB destruction efficiency and rate (same reaction times) obtained from comparable simulant tests, (2) Determine the destruction efficiency of other organics including biphenyl, (3) Identify and quantify the reaction byproducts, and (4) Determine off-gas composition. Batch bench-scale stirred autoclave tests were conducted with simulated and actual Tank 48H wastes at SRNL. Experimental conditions were chosen based on continuous-flow pilot-scale simulant testing performed at Siemens Water Technologies Corporation (SWT) in Rothschild, Wisconsin. The following items were demonstrated as a result of this testing. (1) Tetraphenylborate was destroyed to below detection limits during the 1-hour reaction time at 280 C. Destruction efficiency of TPB was > 99.997%. (2) Other organics (TPB associated compounds), except biphenyl, were destroyed to below their respective detection limits. Biphenyl was partially destroyed in the process, mainly due to its propensity to reside in the vapor phase during the WAO reaction. Biphenyl is expected to be removed in the gas phase during the actual process, which is a continuous-flow system. (3) Reaction byproducts, remnants of MST, and the PUREX sludge, were characterized in this work. Radioactive species, such as Pu, Sr-90 and Cs-137 were quantified in the filtrate and slurry samples. Notably, Cs-137, boron and potassium were shown as soluble as a

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

    DEFF Research Database (Denmark)

    Kehres, Jan

    range from 298 - 1023 K. Correlated crystallite and particle growth due to sintering were observed after the decomposition of the surfactant. Furthermore transformations from rod to spherical particle shape were observed. In situ reduction experiments of a Ni/MgAl2O4 catalyst were performed. The Ni......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....../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...

  13. Elucidation of reaction mechanism for m -cresol hydrodeoxygenation over Fe based catalysts: A kinetic study

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Yongchun; Wang, Yong

    2017-09-01

    Fe based catalysts are promising for hydrodeoxygenation (HDO) of lignin derived phenolics due to their high selectivity for aromatics. In this work, the reaction mechanism of m-cresol HDO on Fe catalysts and the kinetic consequence with Pd addition were elucidated by examining the effect of H2, H2O and m-cresol pressures on toluene formation rate on Fe and PdFe catalysts. A direct CO bond cleavage mechanism is proposed for HDO catalysis on both Fe and PdFe catalysts, while Pd provides a facilitated reaction pathway at the PdFe interface and therefore promotes the catalysis on Fe without changing the high selectivity towards aromatics.

  14. Combined XRD and XANES studies of a Re-promoted Co/γ-Al2O3 catalyst at Fischer–Tropsch synthesis conditions

    DEFF Research Database (Denmark)

    Rønning, Magnus; Tsakoumis, Nikolaos E.; Voronov, Alexey

    2010-01-01

    A cobalt based Fischer–Tropsch catalyst was studied during the initial stages of the reaction at industrially relevant conditions. The catalyst consists of 20wt% cobalt supported on γ-Al2O3 and promoted by 1wt% of rhenium. X-ray diffraction (XRD) in combination with X-ray absorption near edge str...

  15. Mechanistic Studies on Chabazite-Type Methanol-to-Olefin Catalysts: Insights from Time-Resolved UV/Vis Microspectroscopy Combined with Theoretical Simulations

    NARCIS (Netherlands)

    Van Speybroeck, V.; Hemelsoet, K.L.J.; De Wispelaere, K.; Qian, Q.; Van der Mynsbrugge, J.; De Sterck, B.; Weckhuysen, B.M.; Waroquier, M.

    2013-01-01

    The formation and nature of active sites for methanol conversion over solid acid catalyst materials are studied by using a unique combined spectroscopic and theoretical approach. A working catalyst for the methanol-to-olefin conversion has a hybrid organic–inorganic nature in which a cocatalytic

  16. Deactivation of SCR catalysts by potassium: A study of potential alkali barrier materials

    DEFF Research Database (Denmark)

    Olsen, Brian Kjærgaard; Kügler, Frauke; Castellino, Francesco

    2017-01-01

    have been exposed to KCl aerosols at 350 °C in a pilot-scale setup for about 1000 hours. A 3 wt.% V2O5-7 wt.% WO3/TiO2 reference catalyst deactivated with an average rate of 0.91 %/day, and SEM-EDS analysis showed complete potassium penetration of the catalyst wall. A similar monolith coated with 8...

  17. MAGNETO-CHEMICAL CHARACTER STUDIES OF NOVEL FE CATALYSTS FOR COAL LIQUEFACTION

    Energy Technology Data Exchange (ETDEWEB)

    Unknown

    1998-04-01

    The primary objectives of research during this period were: (1) To prepare ferric molybdate-molybdenum trioxide catalysts with different Fe/Mo ratio using co-precipitation method; (2) To investigate the adsorption character, prior to, after adsorption of CO only, and after adsorption of CO+H{sub 2} (syngas) by diffuse reflectance FTIR technique; and (3) To examine the catalytic character of these catalysts.

  18. Catalyst activity maintenance study for the liquid phase dimethyl ether process

    Energy Technology Data Exchange (ETDEWEB)

    Peng, X.D.; Toseland, B.A.; Underwood, R.P. [Air Products and Chemicals, Inc., Allentown, PA (United States)

    1995-12-31

    The co-production of dimethyl ether (DME) and methanol from syngas is a process of considerable commercial attractiveness. DME coproduction can double the productivity of a LPMEOH process when using coal-derived syngas. This in itself may offer chemical producers and power companies increased flexibility and more profitable operation. DME is also known as a clean burning liquid fuel; Amoco and Haldor-Topsoe have recently announced the use of DME as an alternative diesel fuel. Moreover, DME can be an interesting intermediate in the production of chemicals such as olefins and vinyl acetate. The current APCl liquid phase dimethyl ether (LPDME) process utilizes a physical mixture of a commercial methanol synthesis catalyst and a dehydration catalyst (e.g., {gamma}-alumina). While this arrangement provides a synergy that results in much higher syngas conversion per pass compared to the methanol-only process, the stability of the catalyst system suffers. The present project is aimed at reducing catalyst deactivation both by understanding the cause(s) of catalyst deactivation and by developing modified catalyst systems. This paper describes the current understanding of the deactivation mechanism.

  19. A comparative parametric study of a catalytic plate methane reformer coated with segmented and continuous layers of combustion catalyst for hydrogen production

    Science.gov (United States)

    Mundhwa, Mayur; Parmar, Rajesh D.; Thurgood, Christopher P.

    2017-03-01

    A parametric comparison study is carried out between segmented and conventional continuous layer configurations of the coated combustion-catalyst to investigate their influence on the performance of methane steam reforming (MSR) for hydrogen production in a catalytic plate reactor (CPR). MSR is simulated on one side of a thin plate over a continuous layer of nickel-alumina catalyst by implementing an experimentally validated surface microkinetic model. Required thermal energy for the MSR reaction is supplied by simulating catalytic methane combustion (CMC) on the opposite side of the plate over segmented and continuous layer of a platinum-alumina catalyst by implementing power law rate model. The simulation results of both coating configurations of the combustion-catalyst are compared using the following parameters: (1) co-flow and counter-flow modes between CMC and MSR, (2) gas hourly space velocity and (3) reforming-catalyst thickness. The study explains why CPR designed with the segmented combustion-catalyst and co-flow mode shows superior performance not only in terms of high hydrogen production but also in terms of minimizing the maximum reactor plate temperature and thermal hot-spots. The study shows that the segmented coating requires 7% to 8% less combustion-side feed flow and 70% less combustion-catalyst to produce the required flow of hydrogen (29.80 mol/h) on the reforming-side to feed a 1 kW fuel-cell compared to the conventional continuous coating of the combustion-catalyst.

  20. A Study of CO2 Methanation over Ni-Based Catalysts Supported by CNTs with Various Textural Characteristics

    Directory of Open Access Journals (Sweden)

    Yanyan Feng

    2015-01-01

    Full Text Available This work studied the influence of textural characteristics of CNTs on catalytic performance of Ni/CNTs for CO2 methanation. The CNTs supports were prepared by chemical vapor deposition method using Ni/MgO catalysts, and acetonitrile and ethanol were used as carbon sources, respectively. The Ni/CNTs catalysts were prepared via impregnation method and characterized by X-ray diffraction (XRD, N2 adsorption/desorption, and temperature-programmed reduction (H2-TPR techniques. The results indicated that the textural characteristics of CNTs supports significantly impacted on the catalytic performance of Ni/CNTs. The catalyst Ni/CNTs-E (CNTs using ethanol as carbon source had good reducibility, high specific surface area, and moderate defects, resulting in higher CO2 conversion and CH4 yield, followed by Ni/CNTs-C (commercial CNTs and Ni/CNTs-A (CNTs using acetonitrile as carbon source. Based on Arrhenius formula, activation energies of the catalysts were calculated and were found decreased for Ni/CNTs-A and Ni/CNTs-E.

  1. Study of Catalyst, Aging Time and Surfactant Effects on Silica Inorganic Polymer Characteristics

    Directory of Open Access Journals (Sweden)

    M. Pakizeh

    2007-06-01

    Full Text Available In the present study the sol-gel method is used for synthesis of amorphous nanostructure silica polymer using tetraethoxysilane (TEOS as silicon source. This polymer can be used in manufacturing of nanoporous asymmetricmembranes. The effect of catalyst on silica particle size has been studied under acidic and basic conditions.زAcid-catalyzed reaction leads to the formation of fine particles while the base-catalyzed reaction produceslarger particles. The presence of cationic template surfactant namely cetyl pyridinium bromide (CPBزdirects the structural formation of the polymer by preventing the highly branched polymeric clusters. This will increase the effective area of the produced silica membrane. Nitrogen physisorption tests by Brunaver- Emmett-Teller (BET and Barrett-Joyner-Halenda (BJH methods revealed that the surface area of the membrane increases significantly around 5-folds when acid-catalyzed reaction is used. 29Si-NMR test is also used to study the aging time effect on the level of silica polymer branching. The results show that in acidic condition, aging time up to three weeks can still affect branching. The calcinations process in which the organic materials and CPB (surfactant are burned and released from the silica particles, is studied on template free silica materials as well as templated silica materials using TGA and DTA techniques.

  2. STUDY ON THE CONCENTRATION EFFECT OF Nb2O5-ZAA CATALYST TOWARDS TOTAL CONVERSION OF BIODIESEL IN TRANSESTERIFICATION OF WASTED COOKING OIL

    Directory of Open Access Journals (Sweden)

    Astuti Tri Padmaningsih

    2010-06-01

    Full Text Available Study on the concentration effect of Nb2O5-ZAA catalyst towards total conversion of biodiesel has been conducted. The natural zeolite (ZA was activated by dipping in NH4Cl solution and was calcined using N2 atmosphere at 500 °C for 5h to produce the ZAA sample. The Nb2O5-ZAA catalyst was made by mixing the activated natural zeolite (ZAA, Nb2O5 3 % (w/w and oxalic acid 10 % (w/w solution, until the paste was formed, followed by drying and calcining the catalyst for 3 h at 500 °C under N2 atmosphere. Catalyst characterizations were conducted by measuring acidity with NH3 gas using gravimetric method and porosimetric analysis using N2 gas adsorption based on the BET equation by surface area analyzer instrument. The Nb2O5-ZAA catalyst was then used as an acid catalyst in free fatty acid esterification reaction of wasted cooking oil in methanol medium with variation of catalyst concentration: 1.25%; 2.5%; 3.75% and 5% towards the weight of oil+methanol. The reaction was continued by transesterification of triglyceride in the used cooking oil using NaOH catalyst in methanol medium. For comparison, the esterification reaction using H2SO4 catalyst 1.25% towards the weight of oil+methanol has been conducted as well. Methyl ester (biodiesel product was analyzed using Gas Chromatography (GC and Gas Chromatography-Mass Spectrometry (GC-MS. The characters of biodiesel were analyzed using American Society for Testing and Materials (ASTM method. The results showed that modification of ZAA by impregning Nb2O5 3% (w/w increased the total catalyst acidity from 5.00 mmol/g to 5.65 mmol/g. The Nb2O5-ZAA catalyst has specific surface area of 60.61 m2/g, total pore volume of 37.62x10-3 cc/g and average pore radius of 12.41 Å. The Nb2O5-ZAA catalyst with concentration of 1.25%-5% produced higher total conversion of biodiesel than that of H2SO4 catalyst 1.25%. The Nb2O5-ZAA catalyst with concentration of 3.75% produced the highest total conversion of biodiesel, i

  3. Comparative TPR and TPD Studies of Cu and Ca Promotion on Fe-Zn- and Fe-Zn-Zr-Based Fischer-Tropsch Catalysts

    Directory of Open Access Journals (Sweden)

    James Olusola O.

    2015-03-01

    Full Text Available The present study demonstrates the effect of zirconium promotion on Fe-Zn-based catalysts to boost the active sites of Fischer-Tropsch (FT catalysts. The catalysts are also promoted by Cu and Ca and the active sites are examined using Temperature-Programmed Reduction (TPR with H2 and CO and Temperature-Programmed Desorption (TPD with NH3 and CO2. The results are presented as a comparative study between Fe-Zn- and Fe-Zn-Zr-based catalysts. The results show that addition of Zr to Fe-Zn catalysts increases the availability and dispersion of the precursor to the active sites and promotion with Cu and Ca independently and synergistically enhances reduction of Fe-Zn-Zr-based catalysts. The presence of Ca promotes carburisation, while Cu inhibits carburisation. The impact of the Ca and Cu on the surface acidity/basicity is governed by the nature of the interaction between the phases in the catalysts. The extent of reduction reflects the availability and dispersion of the precursor to the active phase, while the extent of carburisation will impact on the selectivity of the catalysts.

  4. Transformation of Active Sites in Fe/SSZ-13 SCR Catalysts during Hydrothermal Aging: A Spectroscopic, Microscopic, and Kinetics Study

    Energy Technology Data Exchange (ETDEWEB)

    Kovarik, Libor; Washton, Nancy M.; Kukkadapu, Ravi K.; Devaraj, Arun; Wang, Aiyong; Wang, Yilin; Szanyi, Janos; Peden, Charles HF; Gao, Feng

    2017-03-07

    Fe/SSZ-13 catalysts (Si/Al = 12, Fe loadings 0.37% and 1.20%) were prepared via solution ion-exchange, and hydrothermally aged at 600, 700 and 800 C. The fresh and aged catalysts were characterized with surface area/pore volume analysis, Mössbauer, solid-state MAS NMR, NO titration FTIR spectroscopies, and TEM and APT imaging. Hydrothermal aging causes dealumination of the catalysts, and transformation of various Fe sites. The latter include conversion of free Fe2+ ions to dimeric Fe(III) species, the agglomeration of isolated Fe-ions to Fe-oxide clusters, and incorporation of Al into the Fe-oxide species. These changes result in complex influences on standard SCR and NO/NH3 oxidation reactions. In brief, mild aging causes catalyst performance enhancement for SCR, while harsh aging at 800 C deteriorates SCR performance. In comparison to Fe/zeolites more prone to hydrothermal degradation, this study demonstrates that via the utilization of highly hydrothermally stable Fe/SSZ-13 catalysts, more accurate correlations between various Fe species and their roles in SCR related chemistries can be made. The authors gratefully acknowledge the US Department of Energy (DOE), Energy Efficiency and Renewable Energy, Vehicle Technologies Office for the support of this work. The research described in this paper was performed in the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated for the US DOE by Battelle.

  5. Comparative study of the methanolysis and ethanolysis of maize oils using alkaline catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Rashid, U.; Ibrahim, M.; Ali, S.; Adil, M.; Hina, S.; Bukhari, I. H.; Yunus, R.

    2012-11-01

    With an increasing population and economic development, fuel from renewable resources needs to be widely explored in order to fulfill the future energy demand. In the present study, bio diesel from maize oil using transesterification reactions with methanol and ethanol was evaluated in the presence of NaOCH{sub 3}, KOCH{sub 3}, NaOCH{sub 2}CH{sub 3}, KOCH{sub 2}CH{sub 3}, NaOH and KOH as catalysts. The influence of reaction variables such as the alcohol to oil molar ratio (3:1-15:1), catalyst concentration (0.25-1.50%) and reaction time (20-120 min) to achieve the maximum yield was determined at fixed reaction temperatures. The optimized variables in the case of methanolysis were 6:1 methanol to oil molar ratio (mol/ mol), 0.75% sodium methoxide concentration (wt%) and 90 min reaction time at 65 degree centigrade, which produced a yield of 97.1% methyl esters. A 9:1 ethanol to oil molar ratio (mol/mol), 1.00% sodium ethoxide concentration (wt%) and 120 min reaction time at 75 degree centigrade were found to produce the maximum ethyl ester yield of up to 85%. The methanolysis of maize oil was depicted more rapidly as compared to the ethanolysis of maize oil. Gas chromatography of the produced bio diesel from maize oil showed high levels of linoleic acid (up to 50.89%) followed by oleic acid (up to 36.00%), palmitic acid (up to 9.98%), oleic acid (up to 1.80%) and linolenic acid (up to 0.98%). The obtained fatty acid esters were further analyzed by fourier transform infrared spectroscopy (FTIR) to ensure the completion of transesterification. The fuel properties of the produced bio diesels i.e. kinematic viscosity, cetane number, oxidative stability, pour point, cloud point, cold filter plugging point, ash content, flash point, acid value, sulfur content, higher heating value, density, methanol content, free glycerol and bound glycerol were determined. The analyses were performed using the FTIR method and the results were compared to the bio diesel standards ASTM and

  6. Catalyst mixtures

    Science.gov (United States)

    Masel, Richard I.; Rosen, Brian A.

    2017-02-14

    Catalysts that include at least one catalytically active element and one helper catalyst can be used to increase the rate or lower the overpotential of chemical reactions. The helper catalyst can simultaneously act as a director molecule, suppressing undesired reactions and thus increasing selectivity toward the desired reaction. These catalysts can be useful for a variety of chemical reactions including, in particular, the electrochemical conversion of CO.sub.2 or formic acid. The catalysts can also suppress H.sub.2 evolution, permitting electrochemical cell operation at potentials below RHE. Chemical processes and devices using the catalysts are also disclosed, including processes to produce CO, OH.sup.-, HCO.sup.-, H.sub.2CO, (HCO.sub.2).sup.-, H.sub.2CO.sub.2, CH.sub.3OH, CH.sub.4, C.sub.2H.sub.4, CH.sub.3CH.sub.2OH, CH.sub.3COO.sup.-, CH.sub.3COOH, C.sub.2H.sub.6, O.sub.2, H.sub.2, (COOH).sub.2, or (COO.sup.-).sub.2, and a specific device, namely, a CO.sub.2 sensor.

  7. Study on the pyrolysis of cellulose for bio-oil with mesoporous molecular sieve catalysts.

    Science.gov (United States)

    Yu, Feng-wen; Ji, Deng-xiang; Nie, Yong; Luo, Yao; Huang, Cheng-jie; Ji, Jian-bing

    2012-09-01

    Mesoporous materials possess a hexagonal array of uniform mesopores, high surface areas, and moderate acidity. They are one of the important catalysts in the field of catalytic pyrolysis. In this paper, mesoporous materials of Al-MCM-41, La-Al-MCM-41, and Ce-Al-MCM-41 were synthesized, characterized, and tested as catalysts in the cellulose catalytic pyrolysis process using a fixed bed pyrolysis reactor. The results showed that mesoporous materials exhibited a strong influence on the pyrolytic behavior of cellulose. The presence of these mesoporous molecular sieve catalysts could vary the yield of products, which was that they could decrease the yield of liquid and char and increase the yield of gas product, and could promote high-carbon chain compounds to break into low-carbon chain compounds. Mesoporous molecular sieve catalysts were benefit to the reaction of dehydrogenation and deoxidation and the breakdown of carbon chain. Further, La-Al-MCM-41 and Ce-Al-MCM-41 catalysts can produce more toluene and 2-methoxy-phenol, as compared to the non-catalytic runs.

  8. Enantioselective polymerization of epoxides using biaryl-linked bimetallic cobalt catalysts: a mechanistic study.

    Science.gov (United States)

    Ahmed, Syud M; Poater, Albert; Childers, M Ian; Widger, Peter C B; LaPointe, Anne M; Lobkovsky, Emil B; Coates, Geoffrey W; Cavallo, Luigi

    2013-12-18

    The enantioselective polymerization of propylene oxide (PO) using biaryl-linked bimetallic salen Co catalysts was investigated experimentally and theoretically. Five key aspects of this catalytic system were examined: (1) the structural features of the catalyst, (2) the regio- and stereoselectivity of the chain-growth step, (3) the probable oxidation and electronic state of Co during the polymerization, (4) the role of the cocatalyst, and (5) the mechanism of monomer enchainment. Several important insights were revealed. First, density functional theory (DFT) calculations provided detailed structural information regarding the regio- and stereoselective chain-growth step. Specifically, the absolute stereochemistry of the binaphthol linker determines the enantiomer preference in the polymerization, and the interaction between the salen ligand and the growing polymer chain is a fundamental aspect of enantioselectivity. Second, a new bimetallic catalyst with a conformationally flexible biphenol linker was synthesized and found to enantioselectively polymerize PO, though with lower enantioselectivity than the binaphthol linked catalysts. Third, DFT calculations revealed that the active form of the catalyst has two active exo anionic ligands (chloride or carboxylate) and an endo polymer alkoxide which can ring-open an adjacent cobalt-coordinated epoxide. Fourth, calculations showed that initiation is favored by an endo chloride ligand, while propagation is favored by the presence of two exo carboxylate ligands.

  9. Theoretical study of the catalytic CO oxidation by Pt catalyst supported on Ge-doped grapheme.

    Science.gov (United States)

    Tang, Yanan; Yang, Zongxian; Dai, Xianqi; Lu, Zhansheng; Zhang, Yanxing; Fu, Zhaoming

    2014-09-01

    The geometry, electronic structure and catalytic properties of the anchored Pt atom on the Ge-doped graphene (Pt/Ge-graphene) substrates are investigated using the first-principles computations. It is found that Ge atoms can form strong covalent bonds with the carbon atoms at the vacancy site on the defective graphene. The Ge-graphene as substrate can effectively anchored Pt atoms and form supported Pt catalyst, which exhibits good catalytic activity for CO oxidation with a two-step route, starting with the Langmuir-Hinshelwood (LH) reaction followed by the Eley-Rideal (ER) reaction. The Ge dopant in graphene plays a vital role in enhancing the substrate-adsorbate interaction through facilitating the charge redistribution at their interfaces. The Ge-graphene can be used as the reactive support to control the stability and activity of the Pt catalysts. This work provides valuable guidance on fabricating carbon-based catalysts for CO oxidation, and validates the reactivity of single-atom catalyst for designing atomic-scale catalysts.

  10. Enantioselective polymerization of epoxides using biaryl-linked bimetallic cobalt catalysts: A mechanistic study

    KAUST Repository

    Ahmed, Syud M.

    2013-12-18

    The enantioselective polymerization of propylene oxide (PO) using biaryl-linked bimetallic salen Co catalysts was investigated experimentally and theoretically. Five key aspects of this catalytic system were examined: (1) the structural features of the catalyst, (2) the regio- and stereoselectivity of the chain-growth step, (3) the probable oxidation and electronic state of Co during the polymerization, (4) the role of the cocatalyst, and (5) the mechanism of monomer enchainment. Several important insights were revealed. First, density functional theory (DFT) calculations provided detailed structural information regarding the regio- and stereoselective chain-growth step. Specifically, the absolute stereochemistry of the binaphthol linker determines the enantiomer preference in the polymerization, and the interaction between the salen ligand and the growing polymer chain is a fundamental aspect of enantioselectivity. Second, a new bimetallic catalyst with a conformationally flexible biphenol linker was synthesized and found to enantioselectively polymerize PO, though with lower enantioselectivity than the binaphthol linked catalysts. Third, DFT calculations revealed that the active form of the catalyst has two active exo anionic ligands (chloride or carboxylate) and an endo polymer alkoxide which can ring-open an adjacent cobalt-coordinated epoxide. Fourth, calculations showed that initiation is favored by an endo chloride ligand, while propagation is favored by the presence of two exo carboxylate ligands. © 2013 American Chemical Society.

  11. Slurry-phase Fischer-Tropsch synthesis and kinetic studies over supported cobalt carbonyl derived catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Withers, H.P. Jr.; Eliezer, K.F.; Mitchell, J.W. (Air Products and Chemicals, Inc., Allentown, PA (USA))

    1990-09-01

    This paper reports the preparation characterization, and performance of cobalt carbonyl cluster based catalysts for use in slurry-phase Fischer--Tropsch (FT) technology investigated. Using metal carbonyls as active metal precursors allows for the control of metal particle size on the support surface, thus offering the potential for better control of activity and selectivity of the FT reaction. Silica as the support provided the highest catalyst activities. A Co{sub 2}(CO){sub 8}/Zr(OPr){sub 4}/SiO{sub 2} catalyst (3.5% cobalt, 6.6% zirconium) was developed as the most active system in the FT slurry reactor and also gave the best liquid fuel selectivity. Selectivity patterns correlated to the Schulz--Flory prediction. These catalysts exhibited low water/gas shift activity. Diesel fuel product produced by this catalyst was high quality. A kinetic expression that took water inhibition into account was verified, yielding an activation energy of 97 kJ/mol for syngas conversion ranging from 34% to 71% at 240--280{degrees} C.

  12. Catalysts for dual fluidised bed biomass gasification - an experimental study at the pilot plant scale

    Energy Technology Data Exchange (ETDEWEB)

    Pfeifer, Christoph; Koppatz, Stefan; Hofbauer, Hermann [Vienna University of Technology, Institute of Chemical Engineering, Vienna (Austria)

    2011-07-15

    Energy from renewable sources is expected to contribute increasingly to the future energy supply. Particularly, the utilisation of biomass via gasification features a high potential for local energy supply. In addition to the conventional heat and power supply, the biomass-derived product gas is utilisable for further conversion, e.g. into liquid fuels, synthetic natural gas or even chemicals. In the field of biomass gasification systems, fluidised bed gasification has achieved notable relevance. Biomass gasification by fluidised bed processing produces high-quality product gas. However, the technical and economical effectiveness is not yet competitive. A major issue is the purity of the product gas, which is mainly focused on the gasification originating tar. A promising option to yield tar-free product gas is the application of a catalyst directly in the fluidised bed process. The present paper outlines catalysts for biomass gasification in fluidised bed processing. Recent activities in the development of gasifier catalysts are highlighted. Different catalysts are described depending on their performance and capability regarding tar conversion. The scope of catalysts ranges from naturally occurring materials to synthetic materials. (orig.)

  13. Tuning the properties of copper-based catalysts based on molecular in situ studies of model systems.

    Science.gov (United States)

    Stacchiola, Darío J

    2015-07-21

    Studying catalytic processes at the molecular level is extremely challenging, due to the structural and chemical complexity of the materials used as catalysts and the presence of reactants and products in the reactor's environment. The most common materials used on catalysts are transition metals and their oxides. The importance of multifunctional active sites at metal/oxide interfaces has been long recognized, but a molecular picture of them based on experimental observations is only recently emerging. The initial approach to interrogate the surface chemistry of catalysts at the molecular level consisted of studying metal single crystals as models for reactive metal centers, moving later to single crystal or well-defined thin film oxides. The natural next iteration consisted in the deposition of metal nanoparticles on well-defined oxide substrates. Metal nanoparticles contain undercoordinated sites, which are more reactive. It is also possible to create architectures where oxide nanoparticles are deposited on top of metal single crystals, denominated inverse catalysts, leading in this case to a high concentration of reactive cationic sites in direct contact with the underlying fully coordinated metal atoms. Using a second oxide as a support (host), a multifunctional configuration can be built in which both metal and oxide nanoparticles are located in close proximity. Our recent studies on copper-based catalysts are presented here as an example of the application of these complementary model systems, starting from the creation of undercoordinated sites on Cu(111) and Cu2O(111) surfaces, continuing with the formation of mixed-metal copper oxides, the synthesis of ceria nanoparticles on Cu(111) and the codeposition of Cu and ceria nanoparticles on TiO2(110). Catalysts have traditionally been characterized before or after reactions and analyzed based on static representations of surface structures. It is shown here how dynamic changes on a catalyst's chemical state

  14. Magnetic and Mössbauer study of metal-zeolite interaction in catalysts

    Science.gov (United States)

    Pannaparayil, Thomas; Oskooie-Tabrizi, M.; Lo, C.; Mulay, L. N.; Melson, G. A.; Rao, V. U. S.

    1984-03-01

    Molecular sieve aluminosilicates, such as ZSM-5 and mordenite, when impregnated with highly dispersed Fe, yield catalysts for the selective conversion of coal-derived syngas (CO+H2) to liquid hydrocarbon fuels. Fe performs the primary Fischer-Tropsch (FT) syngas to yield light olefins which are converted by the acidic (H+) and shape-selective function of the zeolite to high octane gasoline components. The physical aspects of the Fe-mordenite interaction studied by magnetic measurements, Mössbauer, and IR spectroscopy are reported and correlations with the catalytic properties are drawn. Mordenite samples with [SiO2/Al2O3] ratio in the range 12 - 60 were impregnated with 15 wt. % Fe using Fe3(CO)12; decarbonylation yielded superparamagmetic dispersions of γ-Fe2O3, in the range 1.4-5.0 nm; the smallest particles were obtained for a ratio=17. Hydrogen chemisorption also revealed a similar trend in Fe dispersions. No samples, other than the one with a ratio=60 and containing the largest particles could be carbided under usual conditions. The acidity of the mordenite and the aromatics fraction in liquid hydrocarbons from syngas conversion also showed maxima at a ratio=17. The presence of a strong metal-support interaction between Fe and mordenite was thus influenced by the varying ratios in the mordenite in a manner that paralleled the acidity and catalytic activity.

  15. A study of butyl acetate synthesis 3. Analysing adsorption on catalyst

    Directory of Open Access Journals (Sweden)

    Álvaro Orjuela Londoño

    2006-01-01

    Full Text Available Reactive system (acetic acid-n-butanol-butyl acetate-water, in liquid phase, 0.76 Bar pressure adsorption on a cationic exchange resin (Bayer Lewatit K-2431 was studied in this work. Solid particle size distribution was verified and low dispersion was noticed with 86% of total mass between 20 and 30 mesh. The dried solid showed a bi- nodal distribution with 40% above 25 mesh and 45% between 25 and 45 mesh. Resin swelling assays were carried out on pure components and non-reactive binary mixtures and increased matrix volume was observed (2.2 to 3 times higher. Selective adsorption on the reactive system was observed in the sequence: water > n-butanol acid> acetate. Both ideal and non-ideal models were tested for calculating adsorption using a composite isotherm, demonstrating these models’ weakness in representing adsorption on ionic polymer matrices. Calorimetric characterisation assays were carried out on swelled catalyst and a change in solid structure caused by thermal treatment was recognised using infrared scanning.

  16. Theoretical studies on membranes and non-platinum catalysts for polymer electrolyte fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Ushiyama, Hiroshi [Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan ushiyama@chemsys.t.u-tokyo.ac.jp (Japan)

    2015-12-31

    Mechanism of proton transfer among high-density acid groups in the interface between organic and inorganic materials for polymer electrolyte fuel cells has been theoretically examined. It has been clearly shown that the interactions between the phosphate groups at the surface of the inorganic material, zirconium phosphate (ZrP), and the adsorbed water molecules are relatively large and a strong hydrogen-bond network is generated locally. Because of the strong interactions, water molecules can be attached to ZrP and the O–O distance becomes shorter than that in bulk water systems. Because of the short O–O distances and the delocalized charge of each atom, the activation energy of proton transfer at the ZrP surface decreases and causes high proton conductivity even under conditions of high temperature and low humidity. Based on the above studies, the origin of the high proton conductivity of hybrid electrolytes is also discussed. We will also discuss the mechanism of oxygen reduction reaction on non-platinum catalysts such as Ta{sub 3}N{sub 5}.

  17. Quantum Mechanics Studies of Fuel Cell Catalysts and Proton Conducting Ceramics with Validation by Experiment

    Science.gov (United States)

    Tsai, Ho-Cheng

    We carried out quantum mechanics (QM) studies aimed at improving the performance of hydrogen fuel cells. In part I, The challenge was to find a replacement for the Pt cathode that would lead to improved performance for the Oxygen Reduction Reaction (ORR) while remaining stable under operational conditions and decreasing cost. Our design strategy was to find an alloy with composition Pt3M that would lead to surface segregation such that the top layer would be pure Pt, with the second and subsequent layers richer in M. Under operating conditions we expect the surface to have significant O and/or OH chemisorbed on the surface; we searched for M that would remain segregated under these conditions. Using QM we examined surface segregation for 28 Pt3M alloys, where M is a transition metal. We found that only Pt3Os and Pt3Ir showed significant surface segregation when O and OH are chemisorbed on the catalyst surfaces. This result indicates that Pt3Os and Pt 3Ir favor formation of a Pt-skin surface layer structure that would resist the acidic electrolyte corrosion during fuel cell operation environments. We chose to focus on Os because the phase diagram for Pt-Ir indicated that Pt-Ir could not form a homogeneous alloy at lower temperature. To determine the performance for ORR, we used QM to examine intermediates, reaction pathways, and reaction barriers involved in the processes for which protons from the anode reactions react with O2 to form H2O. These QM calculations used our Poisson-Boltzmann implicit solvation model include the effects of the solvent (water with dielectric constant 78 with pH 7 at 298K). We also carried out similar QM studies followed by experimental validation for the Os/Pt core-shell catalyst fabricated by the underpotential deposition (UPD) method. The QM results indicated that the RDS for ORR is a compromise between the OOH formation step (0.37 eV for Pt, 0.23 eV for Pt2ML/Os core-shell) and H2O formation steps (0.32 eV for Pt, 0.22 eV for Pt2ML

  18. A comprehensive study of olefin metathesis catalyzed by Ru-based catalysts

    KAUST Repository

    Poater, Albert

    2015-09-29

    During a Ru-catalyzed reaction of an olefin with an alkylidene moiety that leads to a metallacycle intermediate, the cis insertion of the olefin can occur from two different directions, namely side and bottom with respect to the phosphine or N-heterocyclic ligand (NHC), depending on the first or second generation Grubbs catalyst. Here, DFT calculations unravel to which extent the bottom coordination of olefins with respect is favored over the side coordination through screening a wide range of catalysts, including first and second generation Grubbs catalysts as well as the subsequent Hoveyda derivatives. The equilibrium between bottom and side coordination is influenced by sterics, electronics, and polarity of the solvent. The side attack is favored for sterically less demanding NHC and/or alkylidene ligands. Moreover the generation of a 14-electron species is also discussed, with either pyridine or phosphine ligands to dissociate.

  19. A comprehensive study of olefin metathesis catalyzed by Ru-based catalysts

    Directory of Open Access Journals (Sweden)

    Albert Poater

    2015-09-01

    Full Text Available During a Ru-catalyzed reaction of an olefin with an alkylidene moiety that leads to a metallacycle intermediate, the cis insertion of the olefin can occur from two different directions, namely side and bottom with respect to the phosphine or N-heterocyclic ligand (NHC, depending on the first or second generation Grubbs catalyst. Here, DFT calculations unravel to which extent the bottom coordination of olefins with respect is favored over the side coordination through screening a wide range of catalysts, including first and second generation Grubbs catalysts as well as the subsequent Hoveyda derivatives. The equilibrium between bottom and side coordination is influenced by sterics, electronics, and polarity of the solvent. The side attack is favored for sterically less demanding NHC and/or alkylidene ligands. Moreover the generation of a 14-electron species is also discussed, with either pyridine or phosphine ligands to dissociate.

  20. A comprehensive study of olefin metathesis catalyzed by Ru-based catalysts.

    Science.gov (United States)

    Poater, Albert; Cavallo, Luigi

    2015-01-01

    During a Ru-catalyzed reaction of an olefin with an alkylidene moiety that leads to a metallacycle intermediate, the cis insertion of the olefin can occur from two different directions, namely side and bottom with respect to the phosphine or N-heterocyclic ligand (NHC), depending on the first or second generation Grubbs catalyst. Here, DFT calculations unravel to which extent the bottom coordination of olefins with respect is favored over the side coordination through screening a wide range of catalysts, including first and second generation Grubbs catalysts as well as the subsequent Hoveyda derivatives. The equilibrium between bottom and side coordination is influenced by sterics, electronics, and polarity of the solvent. The side attack is favored for sterically less demanding NHC and/or alkylidene ligands. Moreover the generation of a 14-electron species is also discussed, with either pyridine or phosphine ligands to dissociate.

  1. A study on N2O catalytic decomposition over Co/MgO catalysts.

    Science.gov (United States)

    Shen, Qun; Li, Landong; Li, Jinjun; Tian, Hua; Hao, Zhengping

    2009-04-30

    Different oxide supported cobalt catalysts were prepared by co-precipitation method and tested for the decomposition of nitrous oxide. Co/MgO with cobalt loading of 15% showed the best activity and a 100% N(2)O conversion was obtained at temperatures higher than 700 K. The active phase of cobalt species in Co/MgO catalysts was Co(3)O(4) highly dispersed in the matrices of MgO, based on XRD and XPS results as well as the kinetic analysis. The existence of NO, O(2) and H(2)O in reaction system showed different negative effects on N(2)O decomposition. Nevertheless, a 100% N(2)O conversion could be achieved at 800 K under simulated conditions of tail gas from nitric acid plant. Moreover, Co/MgO catalyst exhibited quite good durability and no obvious activity loss was observed in the 100 h stability test.

  2. Methanol Electro-Oxidation by Meth anol Dehydrogenase Enzymatic Catalysts: A Computational Study

    Science.gov (United States)

    Idupulapati, N. B.; Mainardi, D. S.

    The high-cost of materials and efficiency limitations that chemical fuel cells currently have is a topic of primary concern. For a fuel cell to be effective, strong acidic or alkaline solutions, high temperatures and pressures are needed. Most fuel cells use platinum as catalyst, which is expensive, limited in availability, and easily poisoned by carbon monoxide (CO), a by-product of many hydrogen production reactions in the fuel cell anode chamber. In proton exchange membrane (PEM) fuel cells, the type of fuel used dictates the appropriate type of catalyst needed. Within this context, tolerance to CO is an important issue.

  3. Optimization Study in Biodiesel Production via Response Surface Methodology Using Dolomite as a Heterogeneous Catalyst

    OpenAIRE

    Santos, Regina C. R.; Vieira, Rômulo B.; Valentini, Antoninho

    2014-01-01

    A carbonate mineral, dolomite, was used as a heterogeneous catalyst to produce methyl-esters from soybean oil. The samples were analyzed by XRF, TGA, XRD, TPD-CO2, and SEM. The calcination of dolomite at 800°C/1 h resulted in a highly active mixed metal oxides. In addition, the influence of the reaction variables such as the temperature, catalyst amount, and methanol/soybean oil molar ratio in methyl-ester production was optimized by the application of a central composite design in conjunctio...

  4. DFT study on the impact of the methylaluminoxane cocatalyst in ethylene oligomerization using a titanium-based catalyst

    KAUST Repository

    Pasha, Farhan Ahmad

    2015-01-26

    A computational study within the framework of density functional theory is presented on the oligomerization of ethylene to yield 1-hexene using [(η5-C5H4CMe2C6H5)]TiCl3/MAO] catalyst. This study explicitly takes into account a methylaluminoxane (MAO) cocatalyst model, where the MAO cluster has become an anionic species after having abstracted one chloride anion, yielding a cationic activated catalyst. Hence, the reaction profile was calculated using the zwitterionic system, and the potential energy surface has been compared to the cationic catalytic system. Modest differences were found between the two free energy profiles. However, we show for the first time that the use of a realistic zwitterionic model is required to obtain a Brønsted-Evans-Polanyi relationship between the energy barriers and reaction energies.

  5. Study on the synthesis of novel TiO2-copper porphyrin catalyst and photocatalytic degradation of methyl orange

    Directory of Open Access Journals (Sweden)

    Shaorui CHEN

    2017-10-01

    Full Text Available In order to study the effect of different length side chain catalysts on photocatalytic degradation of methyl orange solution, solving the poroblem of water pollution control, four novel porphyrins and their corresponding copper complexes are synthesized from the starting material 1-naphthol, and their structures are characterized by MS, NMR and elemental analysis. Novel TiO2-porphyrins hybrid systems are prepared and its photocatalytic activity is investigated by photodegradation of methyl orange in aqueous solution under visible light. The results indicate that when there are side chains on the benzene ring of copper-porphyrin derivatives, the photocatalytic activity of substituted TiO2-copper porphyrins is better than TiO2-copper tetraphenyl porphyrin, but the effect of the side chains' length on the activity is not obvious. This study provides an idea for the synthesis of highly efficient catalysts in the future.

  6. A hard X-ray study of a manganese-terpyridine catalyst in a chromium-based Metal Organic Framework

    Energy Technology Data Exchange (ETDEWEB)

    Ramsey, Alexandra V. [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-08-28

    Hydrogen produced from water splitting is a promising source of clean energy. However, a robust catalyst is necessary to carry out the water oxidation step of water splitting. In this study, the catalyst studied was [(terpy)Mn(μ-O)2Mn(terpy)]3+ (MnTD) synthesized in the Metal Organic Framework (MOF) MIL-101(Cr), and the method used for analysis was hard X-ray powder diffraction. The diffraction data was used to detect the presence of MOF in different catalytic stages, and lattice parameters were assigned to the samples containing MOF. Fourier maps were constructed with GSAS II to determine the contents of the MOF as preliminary studies suggested that MnTD may not be present. Results showed that MOF is present before catalysis occurs but disappears by the time 45 minutes of catalysis has ensued. Changes in the MOF’s lattice parameters and location of electron density in the Fourier maps suggest attractions between the MOF and catalyst that may lead to MOF degradation. Fourier maps also revealed limited, if any, amounts of MnTD, even before catalysis occurred. Molecular manganese oxide may be the source of the high rate of water oxidation catalysis in the studied system.

  7. DOE Award No. DE-FC36-03GO13108 NOVEL NON-PRECIOUS METAL CATALYSTS FOR PEMFC: CATALYST SELECTION THROUGH MOLECULAR MODELING AND DURABILITY STUDIES Final Report (September 2003 – October 2008)

    Energy Technology Data Exchange (ETDEWEB)

    Branko N. Popov

    2009-02-20

    The objective of this project is to develop novel non-precious metal electrocatalysts for oxygen reduction reaction (ORR), and demonstrate the potential of the catalysts to perform at least as good as conventional Pt catalysts currently in use in polymer electrolyte membrane fuel cell (PEMFC) with a cost at least 50 % less than a target of 0.2 g (Pt loading)/peak kW and with durability > 2,000 h operation with less than 10 % power degradation. A novel nitrogen-modified carbon-based catalyst was obtained by modifying carbon black with nitrogen-containing organic precursor in the absence of transition metal precursor. The catalyst shows the onset potential of approximately 0.76 V (NHE) for ORR and the amount of H2O2 of approximately 3% at 0.5 V (NHE). Furthermore, a carbon composite catalyst was achieved through the high-temperature pyrolysis of the precursors of transition metal (Co and Fe) and nitrogen supported on the nitrogen-modified carbon-based catalyst, followed by chemical post-treatment. This catalyst showed an onset potential for ORR as high as 0.87 V (NHE), and generated less than 1 % of H2O2. The PEM fuel cell exhibited a current density of 2.3 A cm-2 at 0.2 V for a catalyst loading of 6.0 mg cm-2. No significant performance degradation was observed for 480 h continuous operation. The characterization studies indicated that the metal-nitrogen chelate complexes decompose at the temperatures above 800 oC. During the pyrolysis, the transition metals facilitate the incorporation of pyridinic and graphitic nitrogen groups into the carbon matrix, and the carbon surface modified with nitrogen is active for ORR. In order to elucidate the role of transition metal precursor played in the formation of active sites in the non-precious metal catalysts, a novel ruthenium-based chelate (RuNx) catalyst was synthesized by using RuCl3 and propylene diammine as the Ru and N precursors, respectively, followed by high-temperature pyrolysis. This catalyst exhibited comparable

  8. DOE Award No. DE-FC36-03GO13108 NOVEL NON-PRECIOUS METAL CATALYSTS FOR PEMFC: CATALYST SELECTION THROUGH MOLECULAR MODELING AND DURABILITY STUDIES Final Report (September 2003 – October 2008)

    Energy Technology Data Exchange (ETDEWEB)

    Branko N. Popov

    2009-03-03

    The objective of this project is to develop novel non-precious metal electrocatalysts for oxygen reduction reaction (ORR), and demonstrate the potential of the catalysts to perform at least as good as conventional Pt catalysts currently in use in polymer electrolyte membrane fuel cell (PEMFC) with a cost at least 50 % less than a target of 0.2 g (Pt loading)/peak kW and with durability > 2,000 h operation with less than 10 % power degradation. A novel nitrogen-modified carbon-based catalyst was obtained by modifying carbon black with nitrogen-containing organic precursor in the absence of transition metal precursor. The catalyst shows the onset potential of approximately 0.76 V (NHE) for ORR and the amount of H2O2 of approximately 3% at 0.5 V (NHE). Furthermore, a carbon composite catalyst was achieved through the high-temperature pyrolysis of the precursors of transition metal (Co and Fe) and nitrogen supported on the nitrogen-modified carbon-based catalyst, followed by chemical post-treatment. This catalyst showed an onset potential for ORR as high as 0.87 V (NHE), and generated less than 1 % of H2O2. The PEM fuel cell exhibited a current density of 2.3 A cm-2 at 0.2 V for a catalyst loading of 6.0 mg cm-2. No significant performance degradation was observed for 480 h continuous operation. The characterization studies indicated that the metal-nitrogen chelate complexes decompose at the temperatures above 800 oC. During the pyrolysis, the transition metals facilitate the incorporation of pyridinic and graphitic nitrogen groups into the carbon matrix, and the carbon surface modified with nitrogen is active for ORR. In order to elucidate the role of transition metal precursor played in the formation of active sites in the non-precious metal catalysts, a novel ruthenium-based chelate (RuNx) catalyst was synthesized by using RuCl3 and propylene diammine as the Ru and N precursors, respectively, followed by high-temperature pyrolysis. This catalyst exhibited comparable

  9. 197Au Mössbauer study of the deactivation and reactivation of a carbon-supported AuCl{4/-} hydrochlorination catalyst

    Science.gov (United States)

    Friedl, J.; Wagner, F. E.; Nkosi, B.; Towert, M.; Coville, N. J.; Adams, M. D.; Hutchings, G. J.

    1992-04-01

    Acetylene hydrochlorination catalysts consisting of activated carbon impregnated with a solution of HAuCl4· xH2O in aqua regia have been studied by197Au Mössbauer spectroscopy. The relative amounts of AuCl{4/-}, of Au(0), and of an Au(J) species formed under certain process conditions were determined quantitatively. Deactivation of the catalyst at low and high temperatures was shown to be due to different mechanisms, and the reactivation of the catalyst by Cl2 gas was studied.

  10. Biodiesel synthesis from cottonseed oil using homogeneous alkali catalyst and using heterogeneous multi walled carbon nanotubes: Characterization and blending studies

    Directory of Open Access Journals (Sweden)

    A. Arun Shankar

    2017-03-01

    Full Text Available The trans-esterification of cottonseed oil using strong alkali catalyst and using multi walled carbon nano tubes as catalyst to produce biodiesel was studied. The interaction effects of various factors such as temperature, amount of alkali used, alcohol to oil ratio and reaction time on yield of biodiesel were studied. The maximum yield of 95% biodiesel was obtained. The biodiesel produced was characterized using FT-IR spectral analysis and GC–MS analysis to ascertain the various functional groups and compounds available in it. The properties of biodiesel using homogeneous alkali catalyst and heterogeneous multi walled carbon nanotubes such as calorific value (36.18 MJ/kg, 33.78 MJ/kg, flash point (160 °C, 156 °C and other properties such as viscosity, cloud point, pour point and density were found to determine the quality of biodiesel produced. The studies were done by blending the biodiesel produced with diesel and properties of blended samples were estimated to ascertain the use of blended samples in internal combustion engines.

  11. Hydrotalcite Catalyst for Hydrocracking Calophyllum inophyllum Oil to Biofuel: A Comparative Study with and without Nickel Impregnation

    Directory of Open Access Journals (Sweden)

    Hafshah Hafshah

    2017-05-01

    Full Text Available This research aims to study the effect of nickel impregnation into hydrotalcite catalyst that use to convert Calophyllum inophyllum oil into biofuel through hydrocracking process. Hydrocracking process was carried out under mild condition (350 °C and 20 bar for two hours in a slurry batch reactor. The adding nickel affected the reaction conversion, yield, and selectivity of gasoil. The process of oxygen removal from the compounds in the oil was characterized by Fourier Transform Infrared Spectroscopy (FTIR, and the compositions of the products were determined by Gas Chromatography-Mass Spectrometry (GC-MS. The results of the study successfully proved that nickel impregnated into hydrotalcite catalyst increased the conversion, yield, and selectivity of gasoil up to 98.57 %, 54.15 %, and 81.31 %, respectively. Copyright © 2017 BCREC Group. All rights reserved Received: 15th November 2016; Revised: 22nd February 2017; Accepted: 22nd February 2017 How to Cite: Hafshah, H., Prajitno, D.H., Roesyadi, A. (2017. Hydrotalcite Catalyst for Hydrocracking Calophyllum inophyllum Oil to Biofuel: A Comparative Study with and without Nickel Impregnation. Bulletin of Chemical Reaction Engineering & Catalysis, 12 (2: 273-280 (doi:10.9767/bcrec.12.2.776.273-280 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.12.2.776.273-280

  12. Model study on transesterification of soybean oil to biodiesel with methanol using solid base catalyst.

    Science.gov (United States)

    Liu, Xuejun; Piao, Xianglan; Wang, Yujun; Zhu, Shenlin

    2010-03-25

    Modeling of the transesterification of vegetable oils to biodiesel using a solid base as a catalyst is very important because the mutual solubilities of oil and methanol will increase with the increasing biodiesel yield. The heterogeneous liquid-liquid-solid reaction system would become a liquid-solid system when the biodiesel reaches a certain content. In this work, we adopted a two-film theory and a steady state approximation assumption, then established a heterogeneous liquid-liquid-solid model in the first stage. After the diffusion coefficients on the liquid-liquid interface and the liquid-solid interface were calculated on the basis of the properties of the system, the theoretical value of biodiesel productivity changing with time was obtained. The predicted values were very near the experimental data, which indicated that the proposed models were suitable for the transesterification of soybean oil to biodiesel when solid bases were used as catalysts. Meanwhile, the model indicated that the transesterification reaction was controlled by both mass transfer and reaction. The total resistance will decrease with the increase in biodiesel yield in the liquid-liquid-solid stage. The solid base catalyst exhibited an activation energy range of 9-20 kcal/mol, which was consistent with the reported activation energy range of homogeneous catalysts.

  13. Studies on the promotion of nickel—alumina coprecipitated catalysts: I. Titanium oxide

    NARCIS (Netherlands)

    Lansink Rotgerink, H.G.J.; Mercera, P.D.L.; van Ommen, J.G.; Ross, J.R.H.

    1988-01-01

    A series of TiO2-promoted nickel—alumina catalysts has been prepared and characterized. The promoter was added in various proportions to a calcined coprecipitated nickel—alumina material by adsorption of the acetylacetonate complex of titanium, followed by further calcination and reduction. The

  14. Studies on the promotion of nickel—alumina coprecipitated catalysts: III. Cerium oxide

    NARCIS (Netherlands)

    Lansink Rotgerink, H.G.J.; Slaa, J.C.; van Ommen, J.G.; Ross, J.R.H.

    1988-01-01

    Three series of cerium-promoted nickel—alumina catalysts with different nickel-to-aluminium ratios each containing different amounts of cerium have been prepared and characterized. The calcination and reduction behaviour were found not to be altered by the presence of cerium. Part of the promoter

  15. Studies on the promotion of nickel—alumina coprecipitated catalysts: II. Lanthanum oxide

    NARCIS (Netherlands)

    Lansink Rotgerink, H.G.J.; Paalman, R.P.A.M.; van Ommen, J.G.; Ross, J.R.H.

    1988-01-01

    Two series of lanthanum promoted nickel—alumina catalysts have been prepared by coprecipitation of the metal nitrates, using potassium carbonate. The molar ratio between nickel and the sum of aluminium and lanthanum was kept constant at 2.5 or 9.0 within each series. The calcination and reduction of

  16. Profiling Physicochemical Changes within Catalyst Bodies during Preparation: New Insights from Invasive and Noninvasive Microspectroscopic Studies

    NARCIS (Netherlands)

    Espinosa-Alonso, L.; Beale, A.M.|info:eu-repo/dai/nl/325802068; Weckhuysen, B.M.|info:eu-repo/dai/nl/285484397

    2013-01-01

    Cylindrical or spherical catalyst bodies with sizes ranging from tens of micrometers to a few millimeters have a wide variety of industrial applications. They are crucial in the oil refining industry and in the manufacture of bulk and fine chemicals. Their stability, activity, and selectivity are

  17. Plasma-catalyst interaction studied in a single pellet DBD reactor: dielectric constant effect on plasma dynamics

    Science.gov (United States)

    Butterworth, T.; Allen, R. W. K.

    2017-06-01

    A novel single dielectric pellet DBD that is designed to facilitate studying the interaction between plasmas and catalysts is presented. The influence of material dielectric constant on plasma dynamics across a range of applied voltages is determined through the use of electrical characterisation combined with videos of the discharge. Different discharge modes in nitrogen are observed and their behaviour is characterised. A particular focus is given to the phenomenon known as ‘partial discharging’. This is where incomplete plasma formation occurs between the electrodes of the reactor, which may have implications for the fair testing of catalysts in packed bed reactors. Additionally, the occurrence of an ‘almond shaped’ QV plot in the event of point-to-point discharging in PBRs is explained. This work provides easily implemented analytical techniques that can be applied to understand the behaviour of plasmas within packed bed DBD reactors.

  18. Cluster-derived Ir-Sn/SiO2 catalysts for the catalytic dehydrogenation of propane: A spectroscopic study

    KAUST Repository

    Gallo, Alessandro

    2013-01-01

    Ir-Sn bimetallic silica-based materials have been prepared via deposition of the molecular organometallic clusters (NEt4)2[Ir 4(CO)10(SnCl3)2] and NEt 4[Ir6(CO)15(SnCl3)] or via deposition of Sn organometallic precursor Sn(n-C4H9) 4 onto pre-formed Ir metal particles. These solids possess promising properties, in terms of selectivity, as catalysts for propane dehydrogenation to propene. Detailed CO-adsorption DRIFTS, XANES and EXAFS characterization studies have been performed on these systems in order to compare the structural and electronic evolution of systems in relation to the nature of the Ir-Sn bonds present in the precursor compounds and to propose a structural model of the Ir-Sn species present at the silica surface of the final catalyst. © 2013 The Royal Society of Chemistry.

  19. 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.

  20. Kinetic study of a highly active MgCl2-supported Ziegler-Natta catalyst in liquid pool propylene polymerization. II. The influence of alkyl aluminum and alkoxysilane on catalyst activation and deactivation

    NARCIS (Netherlands)

    Shimizu, Fumihiko; Pater, J.T.M.; van Swaaij, Willibrordus Petrus Maria; Weickert, G.

    2001-01-01

    The influence of alkyl aluminum and alkoxysilane on the kinetics in liquid pool propylene batch polymerization was investigated with a highly active Ziegler-Natta catalyst system that consisted of MgCl2/TiCl4/diester-alkoxysilane/AlR3. In this study, diethyl phthalate and t-BuEtSi(OMe)2 were used as

  1. 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.

  2. Kinetics study of Jatropha oil esterification with ethanol in the presence of tin (II) chloride catalyst for biodiesel production

    Science.gov (United States)

    Kusumaningtyas, Ratna Dewi; Ratrianti, Naomi; Purnamasari, Indah; Budiman, Arief

    2017-01-01

    Jatropha oil is one of the promising feedstocks for biodiesel production. Jatropha oil is non-edible oil hence utilization of this oil would not compete with the needs of food. However, crude jatropha oil usually has high free fatty acid (FFA) content. Due to this fact, direct alkaline-catalyzed transesterification of crude jatropha oil for biodiesel production cannot be performed. FFA in crude jatropha oil will react with a base catalyst, resulting in soap as by product and hindering methyl ester (biodiesel) production. Therefore, prior to a transesterification reaction, it is crucial to run a pretreatment step of jatropha oil which can lower the FFA content in the oil. In this work, the pretreatment process was conducted through the esterification reaction of FFA contained in crude jatropha oil with ethanol over tin (II) chloride catalyst to reduce the acid value of the feedstock. The feedstock was Indonesia crude jatropha oil containing 12.03% of FFA. The esterification reaction was carried out in a batch reactor with a molar ratio of FFA to ethanol was 1:60 and total reaction time was 180 minutes. Tin (II) chloride catalyst was varied at 2.5, 5, 7.5, and 10% wt, whereas the effect of the reaction temperature was studied at 35, 34, 55, and 65 °C. The best reaction conversion was 71.55%, achieved at the following condition: a reaction temperature of 65 °C, catalyst concentration of 10% wt, the reaction time of 180 min, and the molar ratio of FFA to ethanol was 1:60. Kinetics study was also conducted in this work. It was found that esterification reaction of jatropha oil FFA with ethanol catalyzed by tin(II) chloride fitted the first-order pseudo-homogeneous kinetics model. It was also revealed that the frequency factor (A) and the activation energy (Ea) were 4.3864 × 106 min-1 and 56.2513 kJ/mole, respectively.

  3. From porphyrins to pyrphyrins: adsorption study and metalation of a molecular catalyst on Au(111)

    Science.gov (United States)

    Mette, Gerson; Sutter, Denys; Gurdal, Yeliz; Schnidrig, Stephan; Probst, Benjamin; Iannuzzi, Marcella; Hutter, Jürg; Alberto, Roger; Osterwalder, Jürg

    2016-04-01

    The molecular ligand pyrphyrin, a tetradentate bipyridine based macrocycle, represents an interesting but widely unexplored class of molecules. It resembles the well-known porphyrin, but consists of pyridyl subunits instead of pyrroles. Metal complexes based on pyrphyrin ligands have recently shown promise as water reduction catalysts in homogeneous photochemical water splitting reactions. In this study, the adsorption and metalation of pyrphyrin on a single crystalline Au(111) surface is investigated in an ultrahigh vacuum by means of scanning tunneling microscopy, low-energy electron diffraction, X-ray photoelectron spectroscopy and density functional theory. Pyrphyrin coverages of approximately one monolayer and less are obtained by sublimation of the molecules on the substrate kept at room temperature. The molecules self-assemble in two distinct phases of long-range molecular ordering depending on the surface coverage. The deposition of cobalt metal and subsequent annealing lead to the formation of Co-ligated pyrphyrin molecules accompanied by a pronounced change of the molecular self-assembly. Electronic structure calculations taking the herringbone reconstruction of Au(111) into account show that the molecules are physisorbed, but preferred adsorption sites are identified where Co and the N atoms of the two terminal cyano groups are optimally coordinated to the surface Au atoms. An intermediate state of the metalation reaction is observed and the reaction steps for the Co metalation of pyrphyrin molecules on Au(111) are established in a joint experimental and computational effort.The molecular ligand pyrphyrin, a tetradentate bipyridine based macrocycle, represents an interesting but widely unexplored class of molecules. It resembles the well-known porphyrin, but consists of pyridyl subunits instead of pyrroles. Metal complexes based on pyrphyrin ligands have recently shown promise as water reduction catalysts in homogeneous photochemical water splitting

  4. Reaction mechanism of ethylene glycol decomposition on Pt model catalysts: A density functional theory study

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Cun-Qin [College of Chemistry and Environmental Engineering, Shanxi Datong University, Datong 037009, Shanxi Province (China); Department of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Nankai University, Tianjin 300071 (China); Yang, Bo; Pang, Xian-Yong [College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan, 030024 (China); Wang, Gui-Chang, E-mail: wangguichang@nankai.edu.cn [Department of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Nankai University, Tianjin 300071 (China)

    2016-12-30

    Highlights: • DFT calculations were performed to study the ethylene glycol decomposition on Pt. • The final products are CO and H{sub 2} on Pt(111), (100) and (211). • Ethylene glycol decomposition on Pt(111) undergoes via initial O−H bond scission and followed by C−H bond cleavage. • Ethylene glycol decomposition proceeds via initial O−H bond scission and followed by O−H bond cleavage on Pt(100)/(211). - Abstract: Understanding and controlling bond beak sequence is important in catalytic processes. The DFT-GGA method combined with slab model was performed to study the ethylene glycol decomposition on various Pt model catalysts such as close-packed Pt(111), stepped Pt(211) and a more open one, Pt(100). Calculation results show that the adsorption energies of ethylene glycol and other decomposition species depend on the coordination number of surface atom, that is, low coordination number correspond to high adsorption energy. Moreover, it was found that final products of ethylene glycol decomposition are CO and H{sub 2} on all model catalysts, but the reaction mechanism varies: On Pt(111), the first step is O−H bond scission, followed by C−H bond cleavage, namely C{sub 2}H{sub 6}O{sub 2} → HOCH{sub 2}CH{sub 2}O + H → HOCH{sub 2}CHO + 2H→ HOCH{sub 2}CO +3H → OCH{sub 2}CO + 4H → OCHCO + 5H → CO + HCO + 5H → 2CO + 6H→ 2CO + 3H{sub 2}; On Pt(211) and Pt(100), however, it is a second O−H bond cleavage that follows the initial O−H bond scission, that is, C{sub 2}H{sub 6}O{sub 2} → HOCH{sub 2}CH{sub 2}O + H → OCH{sub 2}CH{sub 2}O + 2H → OCHCH{sub 2}O + 3H → OCHCHO + 4H → 2HCO + 4H → 2CO + 6H → 2CO + 3H{sub 2}  on Pt(211), and C{sub 2}H{sub 6}O{sub 2} →HOCH{sub 2}CH{sub 2}O+ H → OCH{sub 2}CH{sub 2}O + 2H→OCHCH{sub 2}O+3H→OCCH{sub 2}O+4H→CO+H{sub 2}CO+4H→CO+HCO+5H→2CO+6H→2CO+3H{sub 2} on Pt(100) For the catalytic order of ethylene glycol to form H{sub 2}, it may be determined based on the rate

  5. 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.

  6. 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...

  7. Surface composition of materials used as catalysts for methanol steam reforming: a theoretical study.

    Science.gov (United States)

    Lim, Kok Hwa; Moskaleva, Lyudmila V; Rösch, Notker

    2006-08-11

    PdZn (1:1) alloy is assumed to be the active component of a promising catalyst for methanol steam reforming. Using density functional calculations on periodic supercell slab models, followed by atomistic thermodynamics modeling, we study the chemical composition of the surfaces PdZn(111) and, as a reference, Cu(111) in contact with water and hydrogen at conditions relevant to methanol steam reforming. For the two surfaces, we determine similar maximum adsorption energies for the dissociative adsorption of H(2), O(2), and the molecular adsorption of H(2)O. These reactions are calculated to be exothermic by about -40, -320, and -20 kJ mol(-1), respectively. Using a thermodynamic analysis based on theoretically predicted adsorption energies and vibrational frequencies, we determine the most favorable surface compositions for given pressure windows. However, surface energy plots alone cannot provide quantitative information on individual coverages in a system of coupled adsorption reactions. To overcome this limitation, we employ a kinetic model, from which equilibrium surface coverages of H, O, OH, and H(2)O are derived. We also discuss the sensitivity of our results and the ensuing conclusions with regard to the model surfaces employed and the inaccuracies of our computational method. Our kinetic model predicts surfaces of both materials, PdZn and Cu, to be essentially adsorbate-free already from very low values of the partial pressure of H(2). The model surfaces PdZn(111) and Cu(111) are predicted to be free of water-related adsorbates for a partial H(2) pressure greater than 10(-8) and 10(-5) atm, respectively.

  8. Ethanolysis conversion of spent frying oils over aluminium, calcium-phosphate based bi-functional formulated catalysts. Catalytic activity assessment study

    Energy Technology Data Exchange (ETDEWEB)

    Al-Zaini, Essam O.; Chesterfield, Dean; Adesina, Adesoji A. [The Univ. of New South Wales, Sydney (Australia). Reactor Engineering and Technology Group; Olsen, John [The Univ. of New South Wales, Sydney (Australia). School of Mechanical and Manufacturing Engineering

    2013-06-01

    The current study compares the catalytic performance of two bi-functional solid catalysts for the transesterification of waste cooking vegetable oil in presence of bio-ethanol acyl-acceptor. The two catalysts were aluminum oxide and seashell-derived calcium oxide supported K{sub 3}PO{sub 4}. The catalytic activity of the produced catalyst samples were assessed and evaluated in terms of their textural and surface chemical properties. Evaluative runs showed that increased amounts of K{sub 3}PO{sub 4} have differently controlled the textural and surface chemical property of the finally synthesised catalyst samples. The behaviour revealed a strong correlation between the percentage yield of ethyl esters EEY% and acid-base site density and strength between the two types of catalysts. Possible leaching test of the catalysts was also used as a measure of performance and as a result, the optimum catalyst, on the basis of both ester yield and resistance to leaching was identified as the sample containing between 10 and 15wt% of K{sub 3}PO{sub 4} on AlO{sub 3} and CaO respectively. (orig.)

  9. A Comparative Study of Basic, Amphoteric, and Acidic Catalysts in the Oxidative Coupling of Methanol and Ethanol for Acrolein Production.

    Science.gov (United States)

    Lilić, Aleksandra; Wei, Tiantian; Bennici, Simona; Devaux, Jean-François; Dubois, Jean-Luc; Auroux, Aline

    2017-09-11

    The impact of acid/base properties (determined by adsorption microcalorimetry) of various catalysts on the cross-aldolization of acetaldehyde and formaldehyde leading to acrolein was methodically studied in oxidizing conditions starting from a mixture of methanol and ethanol. The aldol condensation and further dehydration to acrolein were carried out on catalysts presenting various acid/base properties (MgO, Mg-Al oxides, Mg/SiO 2 , NbP, and heteropolyanions on silica, HPA/SiO 2 ). Thermodynamic calculations revealed that cross-aldolization is always favored compared with self-aldolization of acetaldehyde, which leads to crotonaldehyde formation. The presence of strong basic sites is shown to be necessary, but a too high amount drastically increases CO x production. On strong acid sites, production of acrolein and carbon oxides (CO x ) does not increase with temperature. The optimal catalyst for this process should be amphoteric with a balanced acid/base cooperation of medium strength sites and a small amount (150 kJ mol -1 ). © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Ceria and titania incorporated silica based catalyst prepared from rice husk: adsorption and photocatalytic studies of methylene blue.

    Science.gov (United States)

    Adam, Farook; Muniandy, Lingeswarran; Thankappan, Radhika

    2013-09-15

    Titania and ceria incorporated rice husk silica based catalyst was synthesized via sol-gel method using CTAB and glycerol as surface directing agents at room temperature and labeled as RHS-50Ti10Ce. The catalyst was used to study the adsorption and photodegradation of methylene blue (MB) under UV irradiation. The powder XRD pattern of RHS-50Ti10Ce was much broader (2θ=25-30°) than that of the parent RHS (2θ=22°). The catalyst exhibited type IV isotherm with H3 hysteresis loop, and the TEM images showed partially ordered pore arrangements. The TGA-DTG thermograms confirmed the complete removal of the templates after calcination at 500°C. RHS-50Ti10Ce exhibited excellent adsorption capability with more than 99% removal of MB from a 40 mg L(-1) solution in just 15 min. It also decolorized an 80 mg L(-1) MB solution under UV irradiation in 210 min, which was comparable with the commercialized pure anatase TiO2. Copyright © 2013 Elsevier Inc. All rights reserved.

  11. A possible highly active supported Ni dimer catalyst for O{sub 2} dissociation: A first-principles study

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Shan [College of Physics and Materials Science, Henan Normal University, Xinxiang, Henan 453007 (China); Zhang, Yanxing, E-mail: 2016025@htu.edu.cn [College of Physics and Materials Science, Henan Normal University, Xinxiang, Henan 453007 (China); Zhang, Xilin; Mao, Jianjun [College of Physics and Materials Science, Henan Normal University, Xinxiang, Henan 453007 (China); Yang, Zongxian, E-mail: yzx@henannu.edu.cn [College of Physics and Materials Science, Henan Normal University, Xinxiang, Henan 453007 (China); Collaborative Innovation Center of Nano Functional Materials and Applications, Henan Province (China)

    2017-04-30

    Graphical abstract: The minimum energy paths (MEPs) for the dissociation process of O{sub 2} on the surfaces of bare YSZ (111) and Ni{sub n}/YSZ (111) (n = 1, 2 and 3). - Highlights: • The catalytic activity of supported metal catalysts is closely related to the size of metal particles. • The dissociation of O{sub 2} on the YSZ (111) surface is largely enhanced by the supported Ni cluster. • The supported Ni dimer is predicted to be the smallest Ni cluster needed for efficient O{sub 2} dissociation. • The results would provide an important reference to improve the activity and efficiency of the Ni/YSZ(111) nanocomposite catalysts in cost-effective materials. - Abstract: The adsorption and dissociation of O{sub 2} on the supported small nickel clusters with one-, two-, three-Ni atoms on yttria-stabilized zirconia (YSZ) (111) surfaces, as well as those on the bare YSZ(111) and Ni(111) surfaces are comparatively studied using ab initio density functional theory calculations. It is found that the dissociation of O{sub 2} on the YSZ(111) surface is largely enhanced by the supported Ni dimer, which is predicted to be the smallest Ni cluster needed for efficient O{sub 2} dissociation. The results would provide an important reference to improve the activity and efficiency of the Ni/YSZ(111) nanocomposite catalysts in cost-effective materials.

  12. The role of catalysts in the decomposition of phenoxy compounds in coal: A density functional theory study

    Science.gov (United States)

    Liu, Jiang-Tao; Wang, Ming-Fei; Gao, Zhi-Hua; Zuo, Zhi-Jun; Huang, Wei

    2018-01-01

    The pyrolysis mechanisms of anisole (C6H5OCH3), as a coal-based model compound, on CaO, ZnO and γ-Al2O3 catalysts were studied using density functional theory (DFT). In contrast to the products of pyrolysis (C6H6, H2 and CO), the products of catalytic pyrolysis on CaO, ZnO, and γ-Al2O3 are C6H5OH and C2H4; CO, C5H6 and C2H4; and C6H5OH and C2H4, respectively. Our results indicate that CaO, ZnO and γ-Al2O3 catalysts not only decrease the energy barrier of C6H5OCH3 decomposition but also alter the pyrolysis process and the products. It is also found that the pyrolysis gas H2 alters the products on CaO (C6H5OH and CH4), but it does not affect the products on ZnO and γ-Al2O3. In sum, these catalysts are beneficial for phenoxy compound decomposition.

  13. 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.

  14. Dynamic studies of catalysts for biofuel synthesis in an Environmental Transmission Electron Microscope

    DEFF Research Database (Denmark)

    Duchstein, Linus Daniel Leonhard; Wu, Qiongxiao; Christensen, Jakob Munkholt

    2011-01-01

    The development of transportation fuels from sustainable resources requires new and better production paths. One approach involves the use of biogas to synthesize alcohols, such as methanol or higher alcohols for fuel. For the production of methanol a reduction of processing temperature...... and pressure to lower the process cost and make the product more competitive is desired. Higher alcohols are in general favourable over methanol due to their high energy density and ease of use in current internal combustion engines. However, the yield of higher alcohols in present production routes is poor...... prompting for the development of better catalysts [1]. The Catalysis for Sustainable Energy Project (CASE) at the Technical University of Denmark aims at discovering new and improved catalysts based on density functional theory and on testing the chemical reactivity of the most promising candidates...

  15. Optimization Study in Biodiesel Production via Response Surface Methodology Using Dolomite as a Heterogeneous Catalyst

    Directory of Open Access Journals (Sweden)

    Regina C. R. Santos

    2014-01-01

    Full Text Available A carbonate mineral, dolomite, was used as a heterogeneous catalyst to produce methyl-esters from soybean oil. The samples were analyzed by XRF, TGA, XRD, TPD-CO2, and SEM. The calcination of dolomite at 800°C/1 h resulted in a highly active mixed metal oxides. In addition, the influence of the reaction variables such as the temperature, catalyst amount, and methanol/soybean oil molar ratio in methyl-ester production was optimized by the application of a central composite design in conjunction with the response surface methodology (RSM. The XRF analysis is carried out after the reuses procedure which shows that the deactivation process is mainly due to the selective calcium leaching. Overall, the calcined dolomite exhibited high catalytic activity at moderate operating conditions for biodiesel production.

  16. Development of the advanced nuclear materials -A study on the polymer catalyst process technology-

    Energy Technology Data Exchange (ETDEWEB)

    Kook, Il Hyun; Jung, Heung Suk; Lee, Han Soo; An, Doh Heui; Kang, Heui Suk; Baek, Seung Woo; Lee, Sung Hoh; Sung, Kee Woong; Kim, Kwang Lak; Kim, Jong Hoh; Koo, Je Hyoo; Park, Tae Keun; Kim, Sang Hwan; Yoo, Ryong; Song, Myung Jae; Son, Soon Hwan; Choi, Jung Kil; Lee, Jae Choon; Jung, Moon Kyoo [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1995-07-01

    Heavy water is used as moderator and coolant in pressurized heavy water power plants. According to the governmental long-term plan for power supply, Korea is scheduled to construct new four pressurized heavy water power plants till the year 2006. Total heavy water make-up for these plants would be 22 Mg/a from the year 2006. Reformed hydrogen processes is considered best suited to Korea. Hydrophobic catalysts for this process were manufactured and the performance of hydrogen isotope exchange was investigated. The overall mass transfer coefficients varied between 0.004 and 2.295 m3 HD/m3 Bed.sec. and heavy water separation processes using the catalysts were optimized. 66 figs, 62 tabs, 19 refs. (Author).

  17. Novel metalloporphyrin catalysts for the oxidation of hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Showalter, M.C.; Nenoff, T.M.; Shelnutt, J.A.

    1996-11-01

    Work was done for developing biomimetic oxidation catalysts. Two classes of metalloporphyrin catalysts were studied. The first class of catalysts studied were a novel series of highly substituted metalloporphyrins, the fluorinated iron dodecaphenylporphyrins. These homogeneous metalloporphyrin catalysts were screened for activity as catalysts in the oxidation of hydrocarbons by dioxygen. Results are discussed with respect to catalyst structural features. The second type of catalysts studied were heterogeneous catalysts consisting of metalloporphyrins applied to inorganic supports. Preliminary catalytic testing results with these materials are presented.

  18. Electrochemical and Spectroscopic Study of Mononuclear Ruthenium Water Oxidation Catalysts: A Combined Experimental and Theoretical Investigation

    KAUST Repository

    de Ruiter, J. M.

    2016-09-20

    One of the key challenges in designing light-driven artificial photosynthesis devices is the optimization of the catalytic water oxidation process. For this optimization it is crucial to establish the catalytic mechanism and the intermediates of the catalytic cycle, yet a full description is often difficult to obtain using only experimental data. Here we consider a series of mononuclear ruthenium water oxidation catalysts of the form [Ru(cy)(L)(H2O)](2+) (cy = p-cymene, L = 2,2\\'-bipyridine and its derivatives). The proposed catalytic cycle and intermediates are examined using density functional theory (DFT), radiation chemistry, spectroscopic techniques, and electrochemistry to establish the water oxidation mechanism. The stability of the catalyst is investigated using online electrochemical mass spectrometry (OLEMS). The comparison between the calculated absorption spectra of the proposed intermediates with experimental spectra, as well as free energy calculations with electrochemical data, provides strong evidence for the proposed pathway: a water oxidation catalytic cycle involving four proton-coupled electron transfer (PCET) steps. The thermodynamic bottleneck is identified as the third PCET step, which involves O-O bond formation. The good agreement between the optical and thermodynamic data and DFT predictions further confirms the general applicability of this methodology as a powerful tool in the characterization of water oxidation catalysts and for the interpretation of experimental observables.

  19. Design of Pd-Based Bimetallic Catalysts for ORR: A DFT Calculation Study

    Directory of Open Access Journals (Sweden)

    Lihui Ou

    2015-01-01

    Full Text Available Developing Pd-lean catalysts for oxygen reduction reaction (ORR is the key for large-scale application of proton exchange membrane fuel cells (PEMFCs. In the present paper, we have proposed a multiple-descriptor strategy for designing efficient and durable ORR Pd-based alloy catalysts. We demonstrated that an ideal Pd-based bimetallic alloy catalyst for ORR should possess simultaneously negative alloy formation energy, negative surface segregation energy of Pd, and a lower oxygen binding ability than pure Pt. By performing detailed DFT calculations on the thermodynamics, surface chemistry and electronic properties of Pd-M alloys, Pd-V, Pd-Fe, Pd-Zn, Pd-Nb, and Pd-Ta, are identified theoretically to have stable Pd segregated surface and improved ORR activity. Factors affecting these properties are analyzed. The alloy formation energy of Pd with transition metals M can be mainly determined by their electron interaction. This may be the origin of the negative alloy formation energy for Pd-M alloys. The surface segregation energy of Pd is primarily determined by the surface energy and the atomic radius of M. The metals M which have smaller atomic radius and higher surface energy would tend to favor the surface segregation of Pd in corresponding Pd-M alloys.

  20. Electron microscopy study of the deactivation of nickel based catalysts for bio oil hydrodeoxygenation

    DEFF Research Database (Denmark)

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

    2014-01-01

    Hydrodeoxygenation (HDO) is proposed as an efficient way to remove oxygen in bio-oil, improving its quality as a more sustainable alternative to conventional fuels in terms of CO2 neutrality and relative short production cycle [1]. Ni and Ni-MoS2 nanoparticles supported on ZrO2 show potential as ...... in order to investigate the oxidation of Ni-MoS2/ZrO2 catalyst active phase as a function of different HDO reaction conditions and using methanol as a model molecule for bio-oil.......Hydrodeoxygenation (HDO) is proposed as an efficient way to remove oxygen in bio-oil, improving its quality as a more sustainable alternative to conventional fuels in terms of CO2 neutrality and relative short production cycle [1]. Ni and Ni-MoS2 nanoparticles supported on ZrO2 show potential...... as high-pressure (100 bar) catalysts for purification of bio-oil by HDO. However, the catalysts deactivate in presence of sulfur, chlorine and potassium species, which are all naturally occurring in real bio-oil. The deactivation mechanisms of the Ni/ZrO2 have been investigated through scanning...

  1. Pre-methanation purification study: removal of low concentration gaseous sulfur compounds (catalyst poisons)

    Energy Technology Data Exchange (ETDEWEB)

    Iaccarino, E.P.; Lieberman, M.; Taylor, W.F.

    1978-02-01

    Before catalytic methanation can be used for the commercial production of synthetic natural gas from synthesis gas, the problem of methanation catalyst deactivation must be solved. The nickel catalyst used is easily poisoned by sulfur compounds. It was the purpose of this program to identify and develop a viable and effective pre-methanation purification system to protect the methanation catalyst and therby promote viable coal gasification by the SYNTHANE process. A review and analysis was made of state of the art gaseous sulfur compound removal processes. On the basis of this extensive review, a system was selected for a detailed laboratory evaluation to obtain needed design data. A copper-chromium oxide impregnated activated carbon was selected as the test sorbent and evaluated for its ability to remove specified levels of H/sub 2/S, COS, CS/sub 2/ mercaptans and thiophenes. The levels used of these respective sulfur compounds was dictated by the anticipated performance of the Benfield Hot Potassium Carbonate Process selected for bulk removal of acid gases in the Synthane Process. Experimental runs were made using single component and multicomponent sulfur compound gaseous mixtures in a simulated synthesis gas. Adsorption breakthrough curves were evaluated and estimates were made of the time for breakthrough to occur, and the approximate maximum values of volume of gas that could be processed/volume of carbon used. Using this data, estimates of sorbent requirements, costs, and environmental handling constraints were made for a system to be used in the 72 TPD SYNTHANE pilot plant.

  2. A comparative study on the influence of the platinum catalyst in poly(dimethylsiloxane) based networks synthesis

    DEFF Research Database (Denmark)

    Bejenariu, Anca Gabriela; Poulsen, Julie Øblom; Skov, Anne Ladegaard

    2009-01-01

    The aim of the project is to find the best of three Pt catalysts and their appropriate quantity in order to obtain soft networks in one hour at room temperature. How the choice of catalyst influences the final elastomeric properties is also evaluated. The differences between the catalysts are the...

  3. Structure, Mobility, and Composition of Transition Metal Catalyst Surfaces. High-Pressure Scanning Tunneling Microscopy and Ambient-Pressure X-ray Photoelectron Spectroscopy Studies

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Zhongwei [Univ. of California, Berkeley, CA (United States)

    2013-12-06

    Surface structure, mobility, and composition of transition metal catalysts were studied by high-pressure scanning tunneling microscopy (HP-STM) and ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) at high gas pressures. HP-STM makes it possible to determine the atomic or molecular rearrangement at catalyst surfaces, particularly at the low-coordinated active surface sites. AP-XPS monitors changes in elemental composition and chemical states of catalysts in response to variations in gas environments. Stepped Pt and Cu single crystals, the hexagonally reconstructed Pt(100) single crystal, and Pt-based bimetallic nanoparticles with controlled size, shape and composition, were employed as the model catalysts for experiments in this thesis.

  4. Study on the photocatalytic degradation of methyl orange in water using Ag/ZnO as catalyst by liquid chromatography electrospray ionization ion-trap mass spectrometry.

    Science.gov (United States)

    Chen, Tianwen; Zheng, Yuanhui; Lin, Jin-Ming; Chen, Guonan

    2008-07-01

    A nanocrystal catalyst Ag/ZnO was successfully synthesized using a simple solvothermal method in this study. This catalyst was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results showed that this catalyst was composed of metallic Ag and ZnO. The photodegradation of methyl orange (MO) was investigated in aqueous suspension containing Ag/ZnO catalyst under UV irradiation. Liquid chromatography coupled with electrospray ionization ion-trap mass spectrometry was applied to the analysis of the samples coming from the photocatalytic degradation of MO. The experimental results showed that there were four intermediates existing in the photocatalytic reaction. MO could be mineralized in the Ag/ZnO suspension after 60 min illumination.

  5. Development of a reaction cell for in-situ/operando studies of surface of a catalyst under a reaction condition and during catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Luan; Tao, Franklin, E-mail: franklin.tao.2011@gmail.com [Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Department of Chemical and Petroleum Engineering, University of Kansas, Lawrence, Kansas 66045 (United States)

    2016-06-15

    Tracking surface chemistry of a catalyst during catalysis is significant for fundamental understanding of catalytic performance of the catalyst since it allows for establishing an intrinsic correlation between surface chemistry of a catalyst at its working status and its corresponding catalytic performance. Ambient pressure X-ray photoelectron spectroscopy can be used for in-situ studies of surfaces of different materials or devices in a gas. To simulate the gaseous environment of a catalyst in a fixed-bed a flowing gaseous environment of reactants around the catalyst is necessary. Here, we report the development of a new flowing reaction cell for simulating in-situ study of a catalyst surface under a reaction condition in gas of one reactant or during catalysis in a mixture of reactants of a catalytic reaction. The homemade reaction cell is installed in a high vacuum (HV) or ultrahigh vacuum (UHV) environment of a chamber. The flowing gas in the reaction cell is separated from the HV or UHV environment through well sealings at three interfaces between the reaction cell and X-ray window, sample door and aperture of front cone of an energy analyzer. Catalyst in the cell is heated through infrared laser beam introduced through a fiber optics interfaced with the reaction cell through a homemade feedthrough. The highly localized heating on the sample holder and Au-passivated internal surface of the reaction cell effectively minimizes any unwanted reactions potentially catalyzed by the reaction cell. The incorporated laser heating allows a fast heating and a high thermal stability of the sample at a high temperature. With this cell, a catalyst at 800 °C in a flowing gas can be tracked readily.

  6. In Situ UV-Visible Assessment of Iron-Based High-Temperature Water-Gas Shift Catalysts Promoted with Lanthana: An Extent of Reduction Study

    Directory of Open Access Journals (Sweden)

    Basseem B. Hallac

    2018-02-01

    Full Text Available The extent of reduction of unsupported iron-based high-temperature water-gas shift catalysts with small (<5 wt % lanthana contents was studied using UV-visible spectroscopy. Temperature- programmed reduction measurements showed that lanthana content higher than 0.5 wt % increased the extent of reduction to metallic Fe, while 0.5 wt % of lanthana facilitated the reduction to Fe3O4. In situ measurements on the iron oxide catalysts using mass and UV-visible spectroscopies permitted the quantification of the extent of reduction under temperature-programmed reduction and high-temperature water-gas shift conditions. The oxidation states were successfully calibrated against normalized absorbance spectra of visible light using the Kubelka-Munk theory. The normalized absorbance relative to the fully oxidized Fe2O3 increased as the extent of reduction increased. XANES suggested that the average bulk iron oxidation state during the water-gas shift reaction was Fe+2.57 for the catalyst with no lanthana and Fe+2.54 for the catalysts with 1 wt % lanthana. However, the UV-vis spectra suggest that the surface oxidation state of iron would be Fe+2.31 for the catalyst with 1 wt % lanthana if the oxidation state of iron in the catalyst with 0 wt % lanthana were Fe+2.57. The findings of this paper emphasize the importance of surface sensitive UV-visible spectroscopy for determining the extent of catalyst reduction during operation. The paper highlights the potential to use bench-scale UV-visible spectroscopy to study the surface chemistry of catalysts instead of less-available synchrotron X-ray radiation facilities.

  7. Dynamics of Catalyst Nanoparticles

    DEFF Research Database (Denmark)

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

    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...... that particle sintering is not solely governed by the mechanisms previously proposed. These results are divided into the different phases of the catalyst lifetime....

  8. 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

  9. Study of structural and catalytic properties of Ni catalysts prepared from inorganic complex precursor for Fischer-Tropsch synthesis

    Science.gov (United States)

    Saheli, Sania; Rezvani, Ali Reza; Malekzadeh, Azim

    2017-09-01

    The silica- and alumina- supported Ni catalysts synthesized by thermal decomposition of inorganic precursors were evaluated for Fischer-Tropsch synthesis (FTS); the structural properties and performance of the catalysts were compared to those of samples constructed via impregnation method. The results revealed that the synthesized catalysts have higher catalytic activity comparison to those prepared via the conventional impregnation method. The effect of the preparation method on the structural properties shows that synthesizing the catalyst through inorganic precursor route is more appropriate. Characterization of catalysts is carried out using inductively coupled plasma (ICP), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and BET specific surface area.

  10. 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...

  11. Preparation of Pd-based metal monolithic catalysts and a study of their performance in the catalytic combustion of methane.

    Science.gov (United States)

    Yin, Fengxiang; Ji, Shengfu; Wu, Pingyi; Zhao, Fuzhen; Liu, Hui; Li, Chengyue

    2008-01-01

    A series of Pd/SBA-15/Al2O3/FeCrAl and Pd/5 wt% Ce(1-x)Zr(x)O2/SBA-15/Al2O3/FeCrAl (x = 0-1) metal monolithic catalysts were prepared and characterized by various techniques. The catalytic activity and the stability of the catalysts for methane combustion were evaluated. All the catalysts retain the SBA-15 mesoporous structure, with PdO being confined in its channels. The results show that the addition of Ce(1-x)Zr(x)O2 as promoters can improve the activity and stability of the catalysts. The stabilities of the metal monolithic catalysts are much better than those of Pd/ SBA-15 particle catalysts. The catalyst with ZrO2 as promoter exhibits the best activity and stability (T90= 395 degrees C), and the conversion of methane remains constant during the 700 h test.

  12. Comparative study of the methanolysis and ethanolysis of Maize oil using alkaline catalysts

    Directory of Open Access Journals (Sweden)

    Rashid, U.

    2012-03-01

    Full Text Available With an increasing population and economic development, fuel from renewable resources needs to be widely explored in order to fulfill the future energy demand. In the present study, biodiesel from maize oil using transesterification reactions with methanol and ethanol was evaluated in the presence of NaOCH3, KOCH3, NaOCH2CH3, KOCH2CH3, NaOH and KOH as catalysts. The influence of reaction variables such as the alcohol to oil molar ratio (3:1-15:1, catalyst concentration (0.25-1.50% and reaction time (20-120 min to achieve the maximum yield was determined at fixed reaction temperatures. The optimized variables in the case of methanolysis were 6:1 methanol to oil molar ratio (mol/ mol, 0.75% sodium methoxide concentration (wt% and 90 min reaction time at 65°C, which produced a yield of 97.1% methyl esters. A 9:1 ethanol to oil molar ratio (mol/mol, 1.00% sodium ethoxide concentration (wt% and 120 min reaction time at 75°C were found to produce the maximum ethyl ester yield of up to 85%. The methanolysis of maize oil was depicted more rapidly as compared to the ethanolysis of maize oil. Gas chromatography of the produced biodiesel from maize oil showed high levels of linoleic acid (up to 50.89% followed by oleic acid (up to 36.00%, palmitic acid (up to 9.98%, oleic acid (up to 1.80% and linolenic acid (up to 0.98%. The obtained fatty acid esters were further analyzed by fourier transform infrared spectroscopy (FTIR to ensure the completion of transesterification. The fuel properties of the produced biodiesels i.e. kinematic viscosity, cetane number, oxidative stability, pour point, cloud point, cold filter plugging point, ash content, flash point, acid value, sulfur content, higher heating value, density, methanol content, free glycerol and bound glycerol were determined. The analyses were performed using the FTIR method and the results were compared to the biodiesel

  13. Electrochemical stability and postmortem studies of Pt/SiC catalysts for polymer electrolyte membrane fuel cells.

    Science.gov (United States)

    Stamatin, Serban N; Speder, Jozsef; Dhiman, Rajnish; Arenz, Matthias; Skou, Eivind M

    2015-03-25

    In the presented work, the electrochemical stability of platinized silicon carbide is studied. Postmortem transmission electron microscopy and X-ray photoelectron spectroscopy were used to document the change in the morphology and structure upon potential cycling of Pt/SiC catalysts. Two different potential cycle aging tests were used in order to accelerate the support corrosion, simulating start-up/shutdown and load cycling. On the basis of the results, we draw two main conclusions. First, platinized silicon carbide exhibits improved electrochemical stability over platinized active carbons. Second, silicon carbide undergoes at least mild oxidation if not even silicon leaching.

  14. Electrochemical stability and postmortem studies of Pt/SiC catalysts for polymer electrolyte membrane fuel cells

    DEFF Research Database (Denmark)

    Stamatin, Serban Nicolae; Spéder, József; Dhiman, Rajnish

    2015-01-01

    potential cycle aging tests were used in order to accelerate the support corrosion, simulating start-up/shutdown and load cycling. On the basis of the results, we draw two main conclusions. First, platinized silicon carbide exhibits improved electrochemical stability over platinized active carbons. Second......In the presented work, the electrochemical stability of platinized silicon carbide is studied. Postmortem transmission electron microscopy and X-ray photoelectron spectroscopy were used to document the change in the morphology and structure upon potential cycling of Pt/SiC catalysts. Two different...

  15. Structural and textural study of Ni and/or Co in a common molybdate lattice as catalysts

    Directory of Open Access Journals (Sweden)

    Boukhlouf H.

    2013-09-01

    Full Text Available This work deals with the search for new molybdate catalyst formulations, which are known to be active in light alkane oxidative dehydrogenation, a process which could be replace in the near future the common steam cracking and pure dehydrogenation processes currently used for the production of alkenes. Co, Ni and mixed Ni-Co molybdates of various compositions are prepared by a modified coprecipitation procedure from metal nitrates and ammonium heptamolybdate. Their structural and textural properties were studied by XRD, Raman, B.E.T and XPS. Textural and structural properties of the materials are correlated to the composition.

  16. Nanolithographic Fabrication and Heterogeneous Reaction Studies ofTwo-Dimensional Platinum Model Catalyst Systems

    Energy Technology Data Exchange (ETDEWEB)

    Contreras, Anthony Marshall [Univ. of California, Berkeley, CA (United States)

    2006-05-20

    In order to better understand the fundamental components that govern catalytic activity, two-dimensional model platinum nanocatalyst arrays have been designed and fabricated. These catalysts arrays are meant to model the interplay of the metal and support important to industrial heterogeneous catalytic reactions. Photolithography and sub-lithographic techniques such as electron beam lithography, size reduction lithography and nanoimprint lithography have been employed to create these platinum nanoarrays. Both in-situ and ex-situ surface science techniques and catalytic reaction measurements were used to correlate the structural parameters of the system to catalytic activity.

  17. In situ XANES cell used for the study of lanthanum strontium cuprate deNOx catalysts

    DEFF Research Database (Denmark)

    Hagen, Anke

    2011-01-01

    The potential NOx-reduction electro catalyst lanthanum strontium cuprate has been characterized with an in situ X-ray spectrochemical gas reaction cell. In a series of samples with increasing substitution of trivalent lanthanum by divalent strontium ions, the oxidation state of copper increased......, maintaining charge neutrality, with the concentration of oxygen vacancies likely increasing at substitution ratios larger than Sr/La>0.08. During heating in air, the valence of copper ions in the structure increased. Upon exposure to NO at 500 °C the valence of copper ions in a lanthanum strontium cuprate...... sample decreased, whereas it remained unchanged in the strontium-free lanthanum cuprate sample....

  18. [Experimental studies on low-temperature selective catalytic reduction of NO on magnetic iron-based catalysts].

    Science.gov (United States)

    Yao, Gui-huan; Zhang, Qi; Qin, Ye; Wang, Fang; Lu, Fang; Gui, Ke-ting

    2009-10-15

    Low-temperature selective catalytic reduction (SCR) of NO is a new technique needing urgent development in flue gas cleaning. Elementary studies were done about selective catalytic reduction of NO from flue gas on magnetic iron oxides with ammonia at low and medium temperatures in a fluidized bed, such as Fe3O4 and gamma-Fe2O3. Magnetic field effects for NO removal on gamma-Fe2O3 were also researched with low assisted magnetic fileds. X-ray diffraction spectroscopy was used to identify and characterize the iron oxides catalysts. Results show that gamma-Fe2O3 is active in SCR at low temperatures, and Fe3O4 is apparently less active in SCR than gamma-Fe2O3, but Fe2O3 is also active in ammonia oxidation by O2 above 25 degrees C. Therefore, the optimal catalytic temperature zone in SCR on gamma-Fe2O3 includes 250 degrees C and adjacent temperature zone below it. Furthermore, a better NO conversion, which is 90%, is obtained at 250 degrees C on the gamma-Fe2O3 particle catalyst. In addition, chemisorption of NO on gamma-Fe2O3 is accelerated by assisted magnetic fields at 150-290 degrees C, thus the NO conversion is improved and higher NO removal efficiency of 95% is obtained at 250 degrees C. But the efficiency of NO removal decreases above 290 degrees C with the magnetic field. It is concluded that gamma-FeO3 catalyst is fit to be used in low-temperature SCR of NO with ammonia at 200-250 degrees C, which may suppress oxidation of ammonia and take advantage of positive effects by external magnetic fields.

  19. In situ reduction study of cobalt model Fischer-Tropsch synthesis catalysts.

    Science.gov (United States)

    du Plessis, Hester Esna; Forbes, Roy Peter; Barnard, Werner; Erasmus, Willem Johannes; Steuwer, Axel

    2013-07-28

    Fischer-Tropsch (FT) synthesis is an important process to manufacture hydrocarbons and oxygenated hydrocarbons from mixtures of carbon monoxide and hydrogen (syngas). The catalysis process occurs on, for example, cobalt metal surfaces at elevated temperatures and pressures. A fundamental understanding of the reduction pathway of supported cobalt oxides, and the intermediate species present during the activation, can assist in developing improved industrial supported cobalt catalysts. Hard synchrotron X-rays have the unique ability to probe atomic processes both in terms of phases present as well as the crystallographic and local structure (using the pair distribution function approach) under realistic conditions. In this manuscript we present results from measurements during in situ hydrogen activation of a model Co/alumina catalyst using in situ synchrotron X-ray powder diffraction and pair-distribution function (PDF) analysis on beam line ID31 at the ESRF in Grenoble, France. The PDF analysis showed a substantially improved understanding of the reduction of cobalt oxides, as for the first time all cobalt could be accounted for by using total scattering analysis.

  20. Synthesis of supported catalysts

    NARCIS (Netherlands)

    Jong, Krijn P. de

    1999-01-01

    Research reports on the synthesis of supported catalysts during the review period (1997-1998) have shown the use of carbon nanotubes and new hetropolyanions as examples of novel supports and of novel precursors of active components, respectively. Studies of absorption and precipitation chemistry

  1. Comparative Study of Various Preparation Methods of CuO–CeO2 Catalysts for Oxidation of n–Hexane and iso–Octane

    Directory of Open Access Journals (Sweden)

    Ashutosh Mishra

    2013-03-01

    Full Text Available The complete oxidation of n-Hexane and iso-Octane was studied individually in a fixed bed tubular flow reactor over CuO-CeO2 catalysts synthesized via four different methods namely urea-nitrate combustion method, urea gelation/co-precipitation method, citric acid sol-gel method and co-impregnation method. Laser diffraction was employed in catalysts characterization. The results obtained from the complete conversion of n-Hexane and iso-Octane revealed that the CuO-CeO2 catalysts prepared by urea-nitrate combustion method (UNC showed the best performance than the catalysts prepared by other methods used in the present investigation. CuO-CeO2 catalysts prepared by UNC method achieve total n-Hexane and iso-Octane conversion to CO2 at lower temperatures of 280 0C and 340 0C respectively due to the larger surface area of the catalysts which increases the specific rate of reaction. © 2013 BCREC UNDIP. All rights reservedReceived: 30th October 2012; Revised: 30th November 2012; Accepted: 3rd December 2012[How to Cite: A. Mishra, B.D. Tripathi, A.K. Rai, R. Prasad (2013. Comparative Study of Various Preparation Methods of CuO–CeO2 Catalysts for Oxidation of n–Hexane and iso–Octane. Bulletin of Chemical Reaction Engineering & Catalysis, 7(3: 172-178. (doi:10.9767/bcrec.7.3.4076.172-178][Permalink/DOI: http://dx.doi.org/10.9767/bcrec.7.3.4076.172-178 ] View in  |

  2. Enantioselective Decarboxylative Alkylation Reactions: Catalyst Development, Substrate Scope, and Mechanistic Studies

    KAUST Repository

    Behenna, Douglas C.

    2011-11-14

    α-Quaternary ketones are accessed through novel enantioselective alkylations of allyl and propargyl electrophiles by unstabilized prochiral enolate nucleophiles in the presence of palladium complexes with various phosphinooxazoline (PHOX) ligands. Excellent yields and high enantiomeric excesses are obtained from three classes of enolate precursor: enol carbonates, enol silanes, and racemic β-ketoesters. Each of these substrate classes functions with nearly identical efficiency in terms of yield and enantioselectivity. Catalyst discovery and development, the optimization of reaction conditions, the exploration of reaction scope, and applications in target-directed synthesis are reported. Experimental observations suggest that these alkylation reactions occur through an unusual inner-sphere mechanism involving binding of the prochiral enolate nucleophile directly to the palladium center.

  3. Enhanced carbon tolerance on Ni-based reforming catalyst with Ir alloying: A DFT study

    Science.gov (United States)

    Ahn, Kiyong; Choi, Sungjun; Lee, Jong-Ho; Kim, Byung-Kook; Kim, Jedo; Kim, Hyoungchul

    2017-10-01

    Carbon deposition is a major cause of performance degradation for the Ni-based catalyst used in steam reforming of hydrocarbons. In this work, we perform first principle calculations to show that carbon tolerance behavior can be significantly enhanced by alloying Ni with Ir. The most stable atomic structure predicted by the surface phased diagram shows that Ir atoms prefer to stay on the surface of the alloy ensuring their exposure to the incoming gas. We find that the presence of Ir atoms suppress the surface migration of carbon atoms and weaken the stability of the adsorbed carbon agglomerates. Finally, we elucidate that the local reactivity change caused by the shift in the d-band structure is responsible for such good carbon tolerance behavior.

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

    CERN Document Server

    Bouyssy, P X

    2001-01-01

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

  5. Theoretical Studies in Heterogenous Catalysis: Towards a Rational Design of Novel Catalysts for Hydrodesulfurization and Hydrogen Production

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez,J.A.; Liu, P.

    2008-10-01

    Traditionally, knowledge in heterogeneous catalysis has come through empirical research. Nowadays, there is a clear interest to change this since millions of dollars in products are generated every year in the chemical and petrochemical industries through catalytic processes. To obtain a fundamental knowledge of the factors that determine the activity of heterogeneous catalysts is a challenge for modern science since many of these systems are very complex in nature. In principle, when a molecule adsorbs on the surface of a heterogeneous catalyst, it can interact with a large number of bonding sites. It is known that the chemical properties of these bonding sites depend strongly on the chemical environment around them. Thus, there can be big variations in chemical reactivity when going from one region to another in the surface of a heterogeneous catalyst. A main objective is to understand how the structural and electronic properties of a surface affect the energetics for adsorption processes and the paths for dissociation and chemical reactions. In recent years, advances in instrumentation and experimental procedures have allowed a large series of detailed works on the surface chemistry of heterogeneous catalysts. In many cases, these experimental studies have shown interesting and unique phenomena. Theory is needed to unravel the basic interactions behind these phenomena and to provide a general framework for the interpretation of experimental results. Ideally, theoretical calculations based on density-functional theory have evolved to the point that one should be able to predict patterns in the activity of catalytic surfaces. As in the case of experimental techniques, no single theoretical approach is able to address the large diversity of phenomena occurring on a catalyst. Catalytic surfaces are usually modeled using either a finite cluster or a two-dimensionally periodic slab. Many articles have been published comparing the results of these two approaches. An

  6. Reaction Mechanism of Organocatalytic Michael Addition of Nitromethane to Cinnamaldehyde: A Case Study on Catalyst Regeneration and Solvent Effects.

    Science.gov (United States)

    Świderek, Katarzyna; Nödling, Alexander R; Tsai, Yu-Hsuan; Luk, Louis Y P; Moliner, Vicent

    2018-01-11

    The Michael addition of nitromethane to cinnamaldehyde has been computationally studied in the absence of a catalyst and the presence of a biotinylated secondary amine by a combined computational and experimental approach. The calculations were performed at the density functional theory (DFT) level with the M06-2X hybrid functional, and a polarizable continuum model has been employed to mimic the effect of two different solvents: dichloromethane (DCM) and water. Contrary to common assumption, the product-derived iminium intermediate was absent in both of the solvents tested. Instead, hydrating the C1-C2 double bond in the enamine intermediate directly yields the tetrahedral intermediate, which is key for forming the product and regenerating the catalyst. Enamine hydration is concerted and found to be rate-limiting in DCM but segregated into two non-rate-limiting steps when the solvent is replaced with water. However, further analysis revealed that the use of water as solvent also raises the energy barriers for other chemical steps, particularly the critical step of C-C bond formation between the iminium intermediate and nucleophile; this consequently lowers both the reaction yield and enantioselectivity of this LUMO-lowering reaction, as experimentally detected. These findings provide a logical explanation to why water often enhances organocatalysis when used as an additive but hampers the reaction progress when employed as a solvent.

  7. Axial Ligand Coordination to the C-H Amination Catalyst Rh2(esp)2: A Structural and Spectroscopic Study.

    Science.gov (United States)

    Warzecha, Evan; Berto, Timothy C; Berry, John F

    2015-09-08

    The compound Rh2(esp)2 (esp = α,α,α',α'-tetramethyl-1,3-benzenediproponoate) is the most generally effective catalyst for nitrenoid amination of C-H bonds. However, much of its fundamental coordination chemistry is unknown. In this work, we study the effects of axial ligand coordination to the catalyst Rh2(esp)2. We report here crystal structures, cyclic voltammetry, UV-vis, IR, Raman, and (1)H NMR spectra for the complexes Rh2(esp)2L2 where L = pyridine, 3-picoline, 2,6-lutidine, acetonitrile, and methanol. The compounds all show well-defined π* → σ* electronic transitions in the 16500 to 20500 cm(-1) range, and Rh-Rh stretching vibrations in the range from 304 to 322 cm(-1). Taking these data into account we find that the strength of axial ligand binding to Rh2(esp)2 increases in the series CH3OH ∼ 2,6-lutidine < CH3CN < 3-methylpyridine ∼ pyridine. Quasi-reversible Rh2(4+/5+) redox waves are only obtained when either acetonitrile or no axial ligand is present. In the presence of pyridines, irreversible oxidation waves are observed, suggesting that these ligands destabilize the Rh2 complex under oxidative conditions.

  8. Study on Surface Damage and Performance Degradation of Impregnated Catalyst in Dielectric Barrier Discharge Plasma-Assisted Methane Conversion Processes.

    Science.gov (United States)

    Lee, Chung Jun; Lee, Dae Hoon; Kim, Taegyu

    2018-02-01

    This paper describes the performance degradation of impregnated catalyst in the dielectric barrier discharge (DBD) plasma-assisted methane conversion process. Mn and Ni mixed copper-zinc catalysts, and bare γ-Al2O3 support were exposed to the DBD plasma generated at 1 kHz and 9 kV under CH4 direct conversion for 4 hours. The performance degradation due to the surface damage of the catalyst by the plasma was investigated by SEM analysis.

  9. 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

    Porosity is a factor affecting catalyst efficiency in pelletized form. This implies that care should be taken with uncritically relating activity measurements from transmission operando FTIR to final catalyst performance. lithe pelletizing pressure is excessive, a destruction of the pore structur...... 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...

  10. Kinetic studies of CO2 methanation over a Ni/γ-Al2O3 catalyst.

    Science.gov (United States)

    Hubble, R A; Lim, J Y; Dennis, J S

    2016-10-20

    The production of methane by reacting CO2 with H2 (CO2 methanation) has the potential for producing synthetic natural gas, which could be exported using the existing infrastructure for the distribution of natural gas. The methanation of CO2 was investigated over a wide range of partial pressures of products and reactants using (i) a gradientless, spinning-basket reactor operated in batch mode and (ii) a laboratory-scale packed bed reactor operated continuously. The rate and selectivity of CO2 methanation, using a 12 wt% Ni/γ-Al2O3 catalyst, were explored at temperatures 445-497 K and pressures up to 20 bar. Research with the batch reactor showed that the rate increased with increasing partial pressures of H2 and CO2 when the partial pressures of these reactants were low; however, the rate of reaction was found to be insensitive to changes in the partial pressures of H2 and CO2 when their partial pressures were high. A convenient method of determining the effect of H2O on the rate of reaction was also developed using the batch reactor and the inhibitory effect of H2O on CO2 methanation was quantified. The kinetic measurements were compared with a mathematical model of the reactor, in which different kinetic expressions were explored. The kinetics of the reaction were found to be consistent with a mechanism in which adsorbed CO2 dissociated to adsorbed CO and O on the surface of the catalyst with the rate-limiting step being the subsequent dissociation of adsorbed CO. The ability of the kinetic expressions to predict the results from the continuous, packed-bed reactor was explored, with some discrepancies discussed.

  11. Catalytic Oxidation of Chlorobenzene over MnxCe1-xO2/HZSM-5 Catalysts: A Study with Practical Implications.

    Science.gov (United States)

    Weng, Xiaole; Sun, Pengfei; Long, Yu; Meng, Qingjie; Wu, Zhongbiao

    2017-07-18

    Industrial-use catalysts usually encounter severe deactivation after long-term operation for catalytic oxidation of chlorinate volatile organic compounds (CVOCs), which becomes a "bottleneck" for large-scale application of catalytic combustion technology. In this work, typical acidic solid-supported catalysts of MnxCe1-xO2/HZSM-5 were investigated for the catalytic oxidation of chlorobenzene (CB). The activation energy (Ea), Brønsted and Lewis acidities, CB adsorption and activation behaviors, long-term stabilities, and surficial accumulation compounds (after aging) were studied using a range of analytical techniques, including XPS, H2-TPR, pyridine-IR, DRIFT, and O2-TP-Ms. Experimental results revealed that the Brønsted/Lewis (B/L) ratio of MnxCe1-xO2/HZSM-5 catalysts could be adjusted by ion exchange of H• (in HZSM-5) with Mnn+ (where the exchange with Ce4+ did not distinctly affect the acidity); the long-term aged catalysts could accumulate ca. 14 organic compounds at surface, including highly toxic tetrachloromethane, trichloroethylene, tetrachloroethylene, o-dichlorobenzene, etc.; high humid operational environment could ensure a stable performance for MnxCe1-xO2/HZSM-5 catalysts; this was due to the effective removal of Cl• and coke accumulations by H2O washing, and the distinct increase of Lewis acidity by the interaction of H2O with HZSM-5. This work gives an in-depth view into the CB oxidation over acidic solid-supported catalysts and could provide practical guidelines for the rational design of reliable catalysts for industrial applications.

  12. A Comparative Study of Carbon Nanotubes Synthesized from Co/Zn/Al and Fe/Ni/Al Catalyst

    Directory of Open Access Journals (Sweden)

    Ezekiel Dixon Dikio

    2011-01-01

    Full Text Available The catalyst systems Fe/Ni/Al and Co/Zn/Al were synthesized and used in the synthesis of carbon nanotubes. The carbon nanotubes produced were characterized by Field Emission Scanning Electron Microscope (FE-SEM, Energy Dispersive x-ray Spectroscopy (EDS, Raman spectroscopy, Thermogravimetric Analysis (TGA and Transmission Electron Microscope (TEM. A comparison of the morphological profile of the carbon nanotubes produced from these catalysts indicates the catalyst system Fe/Ni/Al to have produced higher quality carbon nanotubes than the catalyst system Co/Zn/Al.

  13. Parametric study of the decomposition of methane using a NiCu/Al{sub 2}O{sub 3} catalyst in a fluidized bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Pinilla, J.L.; Suelves, I.; Lazaro, M.J.; Moliner, R. [Instituto de Carboquimica, CSIC, Miguel Luesma Castan 4, 50018 Zaragoza (Spain); Palacios, J.M. [Instituto de Catalisis y Petroleoquimica, CSIC, Campus Universidad Autonoma, Cantoblanco, 28049 Madrid (Spain)

    2010-09-15

    CO{sub 2}-free production of hydrogen via catalytic decomposition of methane (CDM) was studied in a fluidized bed reactor (FBR) using a NiCu/Al{sub 2}O{sub 3} catalyst. A parametric study of the effects of some process variables, including catalyst particle size, reaction temperature, space velocity and the ratio of gas flow velocity to the minimum fluidization velocity (u{sub o}/u{sub mf}), was undertaken. A mean particle size of 150 {mu}m allows optimization of results in terms of hydrogen production without agglomeration problems. The operating conditions strongly affect the catalyst performance: hydrogen production was enhanced by increasing operating temperature and lowering space velocity. However, increases in operating temperature, space velocity and the ratio u{sub o}/u{sub mf} provoked increases in the catalyst deactivation rate. At 700 C, carbon was deposited as carbon nanofibers, while higher temperatures promoted the formation of encapsulating carbon, which led to rapid catalyst deactivation. (author)

  14. The deactivation mechanism of Pb on the Ce/TiO2 catalyst for the selective catalytic reduction of NOx with NH3: TPD and DRIFT studies.

    Science.gov (United States)

    Wang, Shu-Xian; Guo, Rui-Tang; Pan, Wei-Guo; Li, Ming-Yuan; Sun, Peng; Liu, Shu-Ming; Liu, Shuai-Wei; Sun, Xiao; Liu, Jian

    2017-02-15

    It was well recognized that Pb had a poisoning effect on a SCR catalyst. In this study, the deactivation mechanism of Pb on the Ce/TiO2 catalyst was investigated based on the characterization results of TPD and in situ DRIFT studies. It was found that the addition of Pb on the Ce/TiO2 catalyst not only inhibited the adsorption and activation of NH3 species, but also led to the decrease of the activity of adsorbed NH3 species in the SCR reaction. The adsorption of NOx species and the oxidation of NO by O2 over the Ce/TiO2 catalyst were also suppressed by the addition of Pb, while the reactivity of adsorbed NO2 species did not decrease. Moreover, the results revealed that the NH3-SCR reaction over the Ce/TiO2 catalyst followed both the E-R and L-H mechanisms, while the NH3-SCR reaction over Ce/TiO2-Pb was mainly controlled by the L-H mechanism. The contributions of the L-H mechanism to the SCR reactions over Ce/TiO2 and Ce/TiO2-Pb decreased with increasing reaction temperature. The deactivation of Ce/TiO2-Pb was mainly attributed to the suppressed NH3 adsorption and activation, accompanied by the inhibited NO oxidation and the decrease of Brønsted acid sites.

  15. Investigation of activity and selectivity of redox catalysts in oxidative ...

    African Journals Online (AJOL)

    In this study, oxidative coupling of methane on Redox catalysts in fluidized bed reactor was investigated. For this purpose, the catalyst Mn-Na2WO4/SiO2 was selected as a Redox catalyst. In order to investigate this catalyst, transient state experiments were designed and performed. Then, the different reaction conditions on ...

  16. Operando chemistry of catalyst surfaces during catalysis.

    Science.gov (United States)

    Dou, Jian; Sun, Zaicheng; Opalade, Adedamola A; Wang, Nan; Fu, Wensheng; Tao, Franklin Feng

    2017-04-03

    Chemistry of a catalyst surface during catalysis is crucial for a fundamental understanding of mechanism of a catalytic reaction performed on the catalyst in the gas or liquid phase. Due to the pressure- or molecular density-dependent entropy contribution of gas or liquid phase of the reactants and the potential formation of a catalyst surface during catalysis different from that observed in an ex situ condition, the characterization of the surface of a catalyst under reaction conditions and during catalysis can be significant and even necessary for understanding the catalytic mechanism at a molecular level. Electron-based analytical techniques are challenging for studying catalyst nanoparticles in the gas or liquid phase although they are necessary techniques to employ. Instrumentation and further development of these electron-based techniques have now made in situ/operando studies of catalysts possible. New insights into the chemistry and structure of catalyst nanoparticles have been uncovered over the last decades. Herein, the origin of the differences between ex situ and in situ/operando studies of catalysts, and the technical challenges faced as well as the corresponding instrumentation and innovations utilized for characterizing catalysts under reaction conditions and during catalysis, are discussed. The restructuring of catalyst surfaces driven by the pressure of reactant(s) around a catalyst, restructuring in reactant(s) driven by reaction temperature and restructuring during catalysis are also reviewed herein. The remaining challenges and possible solutions are briefly discussed.

  17. A study on methanol steam reforming to CO 2 and H 2 over the La 2CuO 4 nanofiber catalyst

    Science.gov (United States)

    Gao, Lizhen; Sun, Gebiao; Kawi, Sibudjing

    2008-01-01

    The La 2CuO 4 crystal nanofibers were prepared by using single-walled carbon nanotubes as templates under mild hydrothermal conditions. The steam reforming of methanol (SRM) to CO 2 and H 2 over such nanofiber catalysts was studied. At the low temperature of 150 °C and steam/methanol=1.3, methanol was completely (100%, 13.8 g/h g catalyst) converted to hydrogen and CO 2 without the generation of CO. Within the 60 h catalyst lifespan test, methanol conversion was maintained at 98.6% (13.6 g/h g catalyst) and with 100% CO 2 selectivity. In the meantime, for distinguishing the advantage of nanoscale catalyst, the La 2CuO 4 bulk powder was prepared and tested for the SRM reaction for comparison. Compared with the La 2CuO 4 nanofiber, the bulk powder La 2CuO 4 showed worse catalytic activity for the SRM reaction. The 100% conversion of methanol was achieved at the temperature of 400 °C, with the products being H 2 and CO 2 together with CO. The catalytic activity in terms of methanol conversion dropped to 88.7% (12.2 g/h g catalyst) in 60 h. The reduction temperature for nanofiber La 2CuO 4 was much lower than that for the La 2CuO 4 bulk powder. The nanofibers were of higher specific surface area (105.0 m 2/g), metal copper area and copper dispersion. The in situ FTIR and EPR experiments were employed to study the catalysts and catalytic process. In the nanofiber catalyst, there were oxygen vacancies. H 2-reduction resulted in the generation of trapped electrons [e] on the vacancy sites. Over the nanofiber catalyst, the intermediate H 2CO/HCO was stable and was reformed to CO 2 and H 2 by steam rather than being decomposed directly to CO and H 2. Over the bulk counterpart, apart from the direct decomposition of H 2CO/HCO to CO and H 2, the intermediate H 2COO might go through two decomposition ways: H 2COO=CO+H 2O and H 2COO=CO 2+H 2.

  18. Preliminary study on optimization of pH, oxidant and catalyst dose for high COD content: solar parabolic trough collector

    Directory of Open Access Journals (Sweden)

    Singh Chandan

    2013-01-01

    Full Text Available Abstract In the present study, solar photocatalytic oxidation has been investigated through laboratory experiments as an alternative to conventional secondary treatment for the organic content reduction of high COD wastewater. Experiments have been performed on synthetic high COD wastewater for solar photocatalytic oxidation using a parabolic trough reactor. Parameters affecting the oxidation of organics have been investigated. The experimental design followed the sequence of dark adsorption studies of organics, followed by photolytic studies (in absence of catalyst and finally photocatalytic studies in presence and absence of additional oxidant (H2O2. All the experimental studies have been performed at pH values of 2, 4, 6,8,10 and the initial pH value of the wastewater (normal pH. For photocatalytic studies, TiO2 has been used as a photocatalyst. Optimization of catalyst dose, pH and H2O2 concentration has been done. Maximum reduction of organic content was observed at the normal pH value of the wastewater (pH = 6.8. The reaction rate was significantly enhanced in presence of hydrogen peroxide. The optimum pH other than the Normal was in the alkaline range. Acidic pH was not found to be favourable for organic content reduction. pH was found to be a dominant factor affecting reaction rate even in presence of H2O2 as an additional oxidant. Also, the solar detoxification process was effective in treating a waste with a COD level of more than 7500 mg/L, which is a otherwise a difficult waste to treat. It can therefore be used as a treatment step in the high organic wastewater treatment during the primary stage also as it effectively reduces the COD content by 86%.

  19. Preliminary study on optimization of pH, oxidant and catalyst dose for high COD content: solar parabolic trough collector.

    Science.gov (United States)

    Singh, Chandan; Chaudhary, Rubina; Gandhi, Kavita

    2013-01-22

    In the present study, solar photocatalytic oxidation has been investigated through laboratory experiments as an alternative to conventional secondary treatment for the organic content reduction of high COD wastewater. Experiments have been performed on synthetic high COD wastewater for solar photocatalytic oxidation using a parabolic trough reactor. Parameters affecting the oxidation of organics have been investigated.The experimental design followed the sequence of dark adsorption studies of organics, followed by photolytic studies (in absence of catalyst) and finally photocatalytic studies in presence and absence of additional oxidant (H2O2). All the experimental studies have been performed at pH values of 2, 4, 6,8,10 and the initial pH value of the wastewater (normal pH). For photocatalytic studies, TiO2 has been used as a photocatalyst. Optimization of catalyst dose, pH and H2O2 concentration has been done. Maximum reduction of organic content was observed at the normal pH value of the wastewater (pH = 6.8). The reaction rate was significantly enhanced in presence of hydrogen peroxide. The optimum pH other than the Normal was in the alkaline range. Acidic pH was not found to be favourable for organic content reduction. pH was found to be a dominant factor affecting reaction rate even in presence of H2O2 as an additional oxidant. Also, the solar detoxification process was effective in treating a waste with a COD level of more than 7500 mg/L, which is a otherwise a difficult waste to treat. It can therefore be used as a treatment step in the high organic wastewater treatment during the primary stage also as it effectively reduces the COD content by 86%.

  20. Preliminary Study on Optimization of pH, Oxidant and Catalyst Dose for High COD Content: Solar Parabolic Trough Collector

    Directory of Open Access Journals (Sweden)

    Chandan Singh

    2013-01-01

    Full Text Available In the present study, solar photocatalytic oxidation has been investigated through laboratory experiments as an alternative to conventional secondary treatment for the organic content reduction of high COD wastewater.Experiments have been performed on synthetic high COD wastewater for solar photocatalytic oxidation using aparabolic trough reactor. Parameters affecting the oxidation of organics have been investigated.The experimental design followed the sequence of dark adsorption studies of organics, followed by photolytic studies (in absence of catalyst and finally photocatalytic studies in presence and absence of additional oxidant(H2O2. All the experimental studies have been performed at pH values of 2, 4, 6,8,10 and the initial pH value of the wastewater (normal pH. For photocatalytic studies, TiO2 has been used as a photocatalyst. Optimization of catalyst dose, pH and H2O2 concentration has been done. Maximum reduction of organic content was observed at the normal pH value of the wastewater (pH = 6.8. The reaction rate was significantly enhanced in presence ofhydrogen peroxide. The optimum pH other than the Normal was in the alkaline range. Acidic pH was not found to be favourable for organic content reduction. pH was found to be a dominant factor affecting reaction rate even in presence of H2O2 as an additional oxidant. Also, the solar detoxification process was effective in treating a waste with a COD level of more than 7500 mg/L, which is a otherwise a difficult waste to treat. It can therefore be used as a treatment step in the high organic wastewater treatment during the primary stage also as it effectively reduces the COD content by 86%.

  1. The Learning School Approach and Student Proficiency in ELA and Math: Preliminary Findings. Catalyst Schools Research Study Report

    Science.gov (United States)

    Hammer, Patricia Cahape

    2016-01-01

    The Learning School initiative completed its pilot testing in June 2016, with 28 schools, called catalyst schools, taking part. Catalyst schools were located in all eight regional education service agencies (RESAs) and were supported by RESA staff in implementing the Learning School approach. Five schools had been part of the program for 2 years…

  2. Characterization and parametrical study of Rh-TPPTS supported ionic liquid phase (SILP) catalysts for ethylene hydroformylation

    DEFF Research Database (Denmark)

    Hanh, Nguyen Thi Ha; Duc, Duc Truong; Thang, Vu Dao

    2012-01-01

    , BET surface area and pore morphology of the catalysts depended on the content of ionic liquid. Hence, catalysts with high ionic liquid loading content showed deactivation at high reaction temperatures, possibly caused by redistribution of ionic liquid out of the pores under these conditions. (C) 2012...

  3. A DRIFTS study of the partial oxidation of ethanol on Rh catalysts; Estudo da oxidacao parcial do etanol em catalisadores de Rh por DRIFTS

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Raquel Lima; Passos, Fabio Barboza, E-mail: fbpassos@vm.uff.br [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Departamento de Engenharia Quimica e de Petroleo

    2013-09-01

    The partial oxidation of ethanol on {gamma}-Al{sub 2}O{sub 3}, CeO{sub 2}, ZrO{sub 2} and Ce{sub x}Zr{sub 1-x}O{sub 2} supported rhodium catalysts was investigated by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). The catalysts were characterized by temperature-programmed reduction (TPR) and cyclohexane dehydrogenation. DRIFTS studies on the partial oxidation of ethanol showed that ethanol is adsorbed dissociatively, through O-H bond breaking, with the formation of ethoxy species, followed by successive dehydrogenation to acetaldehyde and acetyl species. Further oxidation to acetate and carbonate species lead to the formation of CO, CH{sub 4} and H{sub 2} by decomposition. The presence of CeO{sub 2} in the catalysts favored the oxidation steps due to its oxygen storage capacity. (author)

  4. Estudo da oxidação parcial do etanol em catalisadores de Rh por DRIFTS A DRIFTS study of the partial oxidation of ethanol on Rh catalysts

    Directory of Open Access Journals (Sweden)

    Raquel Lima Oliveira

    2013-01-01

    Full Text Available The partial oxidation of ethanol on γ-Al2O3, CeO2, ZrO2 and Ce xZr1-xO2 supported rhodium catalysts was investigated by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS. The catalysts were characterized by temperature-programmed reduction (TPR and cyclohexane dehydrogenation. DRIFTS studies on the partial oxidation of ethanol showed that ethanol is adsorbed dissociatively, through O-H bond breaking, with the formation of ethoxy species, followed by successive dehydrogenation to acetaldehyde and acetyl species. Further oxidation to acetate and carbonate species lead to the formation of CO, CH4 and H2 by decomposition. The presence of CeO2 in the catalysts favored the oxidation steps due to its oxygen storage capacity.

  5. Mössbauer studies of ferrihydrite for Fischer-Tropsch catalysts

    Science.gov (United States)

    Lim, Jung Tae; Kim, Chul Sung; Chun, Dong Hyun; Park, Ji Chan

    2016-01-01

    The 6-line ferrihydrite sample for Ficher-Tropsch catalysts was prepared by using a combination of a co-precipitation technique and a spraydrying method. The crystallographic and magnetic properties of 6-line ferrihydrite sample were investigated by using x-ray diffractometer (XRD), vibrating sample magnetometer (VSM), and Mössbauer spectrometer. The XRD patterns of the ferrihydrite sample, measured at 295 K, showed 6-lines peak and its structure was found to be a single-phased hexagonal with space group of P3m1 according to JCPDS card. The temperaturedependent magnetization curves were measured under 1000 Oe between 4.2 and 300 K, and showed blocking temperature ( T B ) around 110 K. Also, Mössbauer spectra of the 6-line ferrihydrite sample were taken at various temperatures ranging from 4.2 to 295 K. At temperature below T B , the obtained spectra were analyzed as two-sextets for Fe sites, while At temperature above T B , the obtained spectra showed a doublet due to relaxation, resulting from the spin dynamic effect.

  6. CO oxidation on nanoporous gold: A combined TPD and XPS study of active catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Röhe, Sarah [Univ. of Bremen (Germany). Inst. of Applied and Physical Chemistry; Frank, Kristian [Univ. of Bremen (Germany). Inst. of Solid State Physics; Schaefer, Andreas [Univ. of Bremen (Germany). Inst. of Applied and Physical Chemistry; Wittstock, Arne [Univ. of Bremen (Germany). Inst. of Applied and Physical Chemistry; Zielasek, Volkmar [Univ. of Bremen (Germany). Inst. of Applied and Physical Chemistry; Rosenauer, Andreas [Univ. of Bremen (Germany). Inst. of Solid State Physics; Bäumer, Marcus [Univ. of Bremen (Germany). Inst. of Applied and Physical Chemistry

    2012-11-30

    Disks of nanoporous gold (np-Au), produced by leaching of silver from AgAu alloy and prepared as active catalysts for CO oxidation in a continuous-flow reactor, were investigated in detail by x-ray photoelectron spectroscopy and temperature-programmed desorption spectroscopy in ultra-high vacuum. Np-Au exhibits several oxygen species on and in the surface: Chemisorbed oxygen (Oact), probably generated at residual silver sites at the surface, is readily available after np-Au preparation and consumed by CO oxidation. It can be replenished on activated np-Au by exposure to O2. In addition, strongly bound oxygen, probably at subsurface sites, is present as a major species and not consumed by CO oxidation. Pronounced CO desorption at temperatures above 200 K observed after exposing np-Au to CO at 105 K indicates an additional, more stable type of CO binding sites on np-Au as compared to pure gold. Only CO at these binding sites is consumed by oxidation reaction with Oact. In conclusion, we propose that the presence of strongly bound subsurface oxygen stabilizes CO adsorption on np-Au, thereby being as crucial for the observed catalytic activity of np-Au as residual silver.

  7. Study of Horseradish Peroxidase Fixed on Mesoporous Materials as a Chemical Reaction Catalyst

    Science.gov (United States)

    Gao, Mengdan; Dai, Rongji

    2017-12-01

    Nanostructured mesoporous materials is a new type of porous materials, which has been widely used. It has excellent capability in enzymes immobilization, but modification on the chemical bonds of the enzyme reduce the enzymatic activity and rarely used in chemical reactions. The horseradish peroxidase was immobilized on the mesoporous materials with appropriate aperture and its activity and stability was evaluated when catalyzing the nitration reaction of amines and oxidation reaction of thiourea. The optimum mesoporous material to fix the horseradish peroxidase can be obtained by mixing polyoxyethylene - polyoxypropylene-pol, yoxyethylene(P123), 1,3,5-trimethylbenzene(TMB), and tetramethoxysilane (TMOS) at a ratio of 10:1:1, whose surface area and pore volume and pore diameter calculated by BET and BJH model were 402.903m2/g, 1.084cm2/g, 1.084cm2/g respectively. The horseradish peroxidase, immobilized on the mesoporous materials, was applied for catalyzing the nitration reaction of anilines and oxidation reaction of thiourea, produced a high product yield and can be recycled. Thus, it is a strong candidate as a catalysts for oxidation reactions, to be produced at industral scale, due to its high efficiency and low cost.

  8. In situ studies on the structure of copper oxide/zinc oxide catalysts.

    Science.gov (United States)

    Günter, M M; Bems, B; Schlögl, R; Ressler, T

    2001-03-01

    Cu/ZnO supported on alumina is a well-known catalyst for steam reforming of methanol. In this work it is attempted to assess the influence of elemental composition on the resulting active copper phase. XAFS measurements of calcined precursors were carried out at the Cu K edge and the Zn K edge. Corresponding RDF show that both copper oxide and zinc oxide exhibit considerable deviations from a linear dependence of their structure on the composition coinciding with changes in phase composition of hydroxycarbonate precursor. From time-resolved in situ experiments at the Cu K edge the degree of reduction can be monitored using a combination of factor analysis (PCA) and least-squares XANES fitting with suitable reference spectra (e.g. Cu metal, Cu2O, and CuO). It is shown that Cu2O forms prior to Cu. The extent of reduction to Cu exhibited a typical nucleation growth behavior with an enhanced reaction rate for more diluted samples. Adding oxygen to the feed gas leads to the formation of mixed Cu2+ and Cu+ phases accompanied by a complete loss of activity in methanol steam reforming. After switching back to steam reforming conditions the activity is regained.

  9. Water dissociation and CO oxidation over Au/anatase catalyst. A DFT-D2 study

    Science.gov (United States)

    Saqlain, Muhammad Adnan; Hussain, Akhtar; Siddiq, Muhammad; Leitão, Alexandre A.

    2018-03-01

    With the help of DFT-D2 methodology, we have investigated the adsorption of water on clean anatase(001) and Au/anatase(001). In the former case, adsorption energies of H2O differ to small extent computed employing GGA = PW91 and DFT-D2 methods. While the GGA = PW91 predicts that water would desorb close to 650 K on the TiO2 surface, the DFT-D2 predicts that desorption is most likely to occur above 700 K. A comparison of water adsorption on TiO2 and Au/TiO2 surfaces shows that the TiO2 prefers dimer adsorption whereas the Au/TiO2 prefers monomer adsorption. We found that the diffusion of surface hydroxyls on to the Au cluster from the Au/TiO2 periphery is unlikely and it seems that the CO oxidation would occur at the Au/TiO2 boundary. The results show that water dissociation and CO oxidation steps occur easily on Au/TiO2 indicating that this could be good alternative catalyst for water gas shift reaction industry.

  10. Study on the non-isothermal curing kinetics of a polyfurfuryl alcohol bioresin by DSC using different amounts of catalyst

    DEFF Research Database (Denmark)

    Dominguez Toribio, Juan Carlos; Grivel, Jean-Claude; Madsen, Bo

    2012-01-01

    The curing kinetics of a biomass-based polyfurfuryl alcohol resin with three different amounts of catalyst was studied by DSC non-isothermal measurements using seven heating rates. The change of the activation energy of the curing process was obtained by the isoconversional methods of Kissinger...... and gelling of the resin which leads to a constrained mobility of the polymer chains; and a final stage, where the activation energy decreases more rapidly due to the formation of a rigid molecular network that restricts diffusion processes. Altogether, the obtained knowledge of the curing kinetics will form...... a valuable contribution to the design of improved cure cycles for manufacturing of composite materials with a polyfurfuryl alcohol matrix....

  11. A study of catalytic activity, constituent, and structure of V-Ag catalyst for selective oxidation of toluene to benzaldehyde

    Energy Technology Data Exchange (ETDEWEB)

    Hui-Liang, Zhang; Wei, Zhong; Xiang, Duan; Xian-Cai, Fu (Nanjing Univ. (China))

    1991-06-01

    A series of V-Ag mixed oxide catalysts with various atomic ratios of V and Ag were prepared by a solution-mixing method. XRD, TEM, SMEA (surface micro-area element analysis), ESR, FT-IR, etc., were used to study the physicochemical properties of the catalysts. The experimental results showed that when silver was introduced into the vanadium pentoxide, the V{double bond}O bond was weakened, and the specific activity of the sample increased. When the atomic ratios of V/Ag were set between 3/1 and 1/1, the selectivity for benzaldehyde increased. In particular, when the V/Ag ratio equaled 2.16, the selectivity for benzaldehyde was greatest, the absorption peak of 900 cm{sup {minus}1} in FT-IR shifted to lower energy, and the relative quantity of V{sup 4 {minus}} measured with ESR appeared the highest. After reaction, XRD showed the main phases of the catalyst to exist as Ag{sub 0{center dot}80}V{sub 2}O{sub 5}, and Ag{sub 0{center dot}68}V{sub 2}O{sub 5}, with a minor Ag phase. Small amounts of VO{sub 2} and V{sub 2}O{sub 4} were also detected. On the two component oxides of vanadium-silver, the toluene oxidation appeared to proceed through two parallel reaction paths: side-chain oxidation of toluene and oxidation coupling. The sample of pure silver promoted cleavage of the carbon ring of toluene and produced deep-oxidation products in large quantity, while the sample of pure V{sub 2}O{sub 5} promoted the oxidative coupling of toluene. After the addition of silver to V{sub 2}O{sub 5}, however the oxidative coupling reaction was depressed, and the silver-vanadium oxide phases, Ag{sub 0{center dot}80}V{sub 2}O{sub 5} and Ag{sub 0{center dot}68}V{sub 2}O{sub 5} were formed. These two phases are responsible for the selective oxidation of toluene.

  12. Novel Anode Catalyst for Direct Methanol Fuel Cells

    OpenAIRE

    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 diffracti...

  13. Radio-Frequency-Based NH3-Selective Catalytic Reduction Catalyst Control: Studies on Temperature Dependency and Humidity Influences

    Directory of Open Access Journals (Sweden)

    Markus Dietrich

    2017-07-01

    Full Text Available The upcoming more stringent automotive emission legislations and current developments have promoted new technologies for more precise and reliable catalyst control. For this purpose, radio-frequency-based (RF catalyst state determination offers the only approach for directly measuring the NH3 loading on selective catalytic reduction (SCR catalysts and the state of other catalysts and filter systems. Recently, the ability of this technique to directly control the urea dosing on a current NH3 storing zeolite catalyst has been demonstrated on an engine dynamometer for the first time and this paper continues that work. Therefore, a well-known serial-type and zeolite-based SCR catalyst (Cu-SSZ-13 was investigated under deliberately chosen high space velocities. At first, the full functionality of the RF system with Cu-SSZ-13 as sample was tested successfully. By direct RF-based NH3 storage control, the influence of the storage degree on the catalyst performance, i.e., on NOx conversion and NH3 slip, was investigated in a temperature range between 250 and 400 °C. For each operation point, an ideal and a critical NH3 storage degree was found and analyzed in the whole temperature range. Based on the data of all experimental runs, temperature dependent calibration functions were developed as a basis for upcoming tests under transient conditions. Additionally, the influence of exhaust humidity was observed with special focus on cold start water and its effects to the RF signals.

  14. Radio-Frequency-Based NH₃-Selective Catalytic Reduction Catalyst Control: Studies on Temperature Dependency and Humidity Influences.

    Science.gov (United States)

    Dietrich, Markus; Hagen, Gunter; Reitmeier, Willibald; Burger, Katharina; Hien, Markus; Grass, Philippe; Kubinski, David; Visser, Jaco; Moos, Ralf

    2017-07-12

    The upcoming more stringent automotive emission legislations and current developments have promoted new technologies for more precise and reliable catalyst control. For this purpose, radio-frequency-based (RF) catalyst state determination offers the only approach for directly measuring the NH₃ loading on selective catalytic reduction (SCR) catalysts and the state of other catalysts and filter systems. Recently, the ability of this technique to directly control the urea dosing on a current NH₃ storing zeolite catalyst has been demonstrated on an engine dynamometer for the first time and this paper continues that work. Therefore, a well-known serial-type and zeolite-based SCR catalyst (Cu-SSZ-13) was investigated under deliberately chosen high space velocities. At first, the full functionality of the RF system with Cu-SSZ-13 as sample was tested successfully. By direct RF-based NH₃ storage control, the influence of the storage degree on the catalyst performance, i.e., on NOx conversion and NH₃ slip, was investigated in a temperature range between 250 and 400 °C. For each operation point, an ideal and a critical NH₃ storage degree was found and analyzed in the whole temperature range. Based on the data of all experimental runs, temperature dependent calibration functions were developed as a basis for upcoming tests under transient conditions. Additionally, the influence of exhaust humidity was observed with special focus on cold start water and its effects to the RF signals.

  15. UV-Raman spectroscopy, X-ray photoelectron spectroscopy, and temperature programmed desorption studies of model and bulk heterogeneous catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Tewell, Craig Richmond [Univ. of California, Berkeley, CA (United States)

    2002-01-01

    X-ray photoelectron spectroscopy (XPS) and Temperature Programmed Desorption (TPD) have been used to investigate the surface structure of model heterogeneous catalysts in ultra-high vacuum (UHV). UV-Raman spectroscopy has been used to probe the structure of bulk model catalysts in ambient and reaction conditions. The structural information obtained through UV-Raman spectroscopy has been correlated with both the UHV surface analysis and reaction results. The present day propylene and ethylene polymerization catalysts (Ziegler-Natta catalysts) are prepared by deposition of TiCl4 and a Al(Et)3 co-catalyst on a microporous Mg-ethoxide support that is prepared from MgCl2 and ethanol. A model thin film catalyst is prepared by depositing metallic Mg on a Au foil in a UHV chamber in a background of TiCl4 in the gas phase. XPS results indicate that the Mg is completely oxidized to MgCl2 by TiCl4 resulting in a thin film of MgCl2/TiClx, where x = 2, 3, and 4. To prepare an active catalyst, the thin film of MgCl2/TiClx on Au foil is enclosed in a high pressure cell contained within the UHV chamber and exposed to ~1 Torr of Al(Et)3.

  16. Radio-Frequency-Based NH3-Selective Catalytic Reduction Catalyst Control: Studies on Temperature Dependency and Humidity Influences

    Science.gov (United States)

    Dietrich, Markus; Hagen, Gunter; Reitmeier, Willibald; Burger, Katharina; Hien, Markus; Grass, Philippe; Kubinski, David; Visser, Jaco; Moos, Ralf

    2017-01-01

    The upcoming more stringent automotive emission legislations and current developments have promoted new technologies for more precise and reliable catalyst control. For this purpose, radio-frequency-based (RF) catalyst state determination offers the only approach for directly measuring the NH3 loading on selective catalytic reduction (SCR) catalysts and the state of other catalysts and filter systems. Recently, the ability of this technique to directly control the urea dosing on a current NH3 storing zeolite catalyst has been demonstrated on an engine dynamometer for the first time and this paper continues that work. Therefore, a well-known serial-type and zeolite-based SCR catalyst (Cu-SSZ-13) was investigated under deliberately chosen high space velocities. At first, the full functionality of the RF system with Cu-SSZ-13 as sample was tested successfully. By direct RF-based NH3 storage control, the influence of the storage degree on the catalyst performance, i.e., on NOx conversion and NH3 slip, was investigated in a temperature range between 250 and 400 °C. For each operation point, an ideal and a critical NH3 storage degree was found and analyzed in the whole temperature range. Based on the data of all experimental runs, temperature dependent calibration functions were developed as a basis for upcoming tests under transient conditions. Additionally, the influence of exhaust humidity was observed with special focus on cold start water and its effects to the RF signals. PMID:28704929

  17. Oxidative conversion of propane in a microreactor in the presence of plasma over MgO based catalysts-an experimental study

    NARCIS (Netherlands)

    Trionfetti, C.; Agiral, A.; Gardeniers, Johannes G.E.; Lefferts, Leonardus; Seshan, Kulathuiyer

    2008-01-01

    In this work, oxidative cracking of propane was studied in a microreactor containing a catalyst. A dielectric barrier discharge (DBD) allows one to generate a cold microplasma, which activates propane forming radicals, at room temperature and atmospheric pressure. Homogeneous and well crystalline

  18. Role of Re in Pt-Re/TiO2 catalyst for water gas shift reaction: A mechanistic and kinetic study.

    NARCIS (Netherlands)

    Azzam, K.G.H.; Babych, Igor V.; Seshan, Kulathuiyer; Lefferts, Leonardus

    2008-01-01

    Transient kinetic studies and in situ FTIR spectroscopy were used to follow the reaction sequences that occur during water gas shift (WGS) reaction over Pt–Re/TiO2 catalyst. Results pointed to contributions of an associative formate route with redox regeneration and two classical redox routes

  19. Catalytic control of diesel engine particulate emission: studies on model reactions over a EURO Pt-1 (Pt/SiO@#2@#) catalyst

    NARCIS (Netherlands)

    Xue, E.; Xue, E.; Seshan, Kulathuiyer; van Ommen, J.G.; Ross, J.R.H.; Ross, J.R.H.

    1993-01-01

    The catalytic oxidation of nitric oxide to nitrogen dioxide in the presence of sulphur dioxide over a standard Pt/SiO2 catalyst (EuroPt-1) was studied. The gas-phase reactions between nitric oxide, sulphur dioxide and oxygen were found to be insignificant under the experimental conditions concerned.

  20. Understanding the promotion effect of lanthanum oxide on gold-based catalysts in the partial oxidation of methanol by in situ XAFS and DSC studies

    NARCIS (Netherlands)

    Hereijgers, B.P.C.; Eggenhuisen, T.M.; de Jong, K.P.; Talsma, H.; van der Eerden, A.M.J.; Beale, A.M.; Weckhuysen, B.M.

    2011-01-01

    Promoting supported gold nanoparticles with lanthanum oxide largely increases the hydrogen selectivity in the partial oxidation of methanol. In this study, the origin of the promotion effect of lanthanum oxide on supported gold catalysts was investigated. The formation of small gold nanoparticles on

  1. Study of Hopcalite (CuMnOx Catalysts Prepared Through A Novel Route for the Oxidation of Carbon Monoxide at Low Temperature

    Directory of Open Access Journals (Sweden)

    Subhashish Dey

    2017-10-01

    How to Cite: Dey, S., Dhal, G.C., Mohan, D., Prasad, R. (2017. Study of Hopcalite (CuMnOx Catalysts Prepared through A Novel Route for the Oxidation of Carbon Monoxide at Low Temperature. Bulletin of Chemical Reaction Engineering & Catalysis, 12 (3: 393-407 (doi:10.9767/bcrec.12.3.882.393-407

  2. PILOT-SCALE STUDY OF THE EFFECT OF SELECTIVE CATALYTIC REDUCTION CATALYST ON MERCURY SPECIATION IN ILLINOIS AND POWDER RIVER BASIN COAL COMBUSTION FLUE GASES

    Science.gov (United States)

    A study was conducted to investigate the effect of selective catalytic reduction (SCR) catalyst on mercury (Hg) speciation in bituminous and subbituminous coal combustion flue gases. Three different Illinois Basin bituminous coals (from high to low sulfur and chlorine) and one Po...

  3. Epoxidation of Unfunctionalized Olefins by Mn(salen) Catalyst Using Organic Peracids as Oxygen Source: A Theoretical Study

    National Research Council Canada - National Science Library

    Ilja V. Khavrutskii; Djamaladdin G. Musaev; Keiji Morokuma; Barry M. Trost

    2004-01-01

    ...)] method in two different regimes: with and without an axial ligand. The acylperoxo complexes of Mn II, III, IV in cisON cisNO and trans geometrical configurations cannot compete with the catalyst-free Prilezhaev epoxidation...

  4. Thiophene hydrodesulfurization over CoMo/Al2O3-CuY catalysts: Temperature effect study

    Directory of Open Access Journals (Sweden)

    Yamina Boukoberine

    2016-09-01

    Full Text Available CoMo/γ-Al2O3-CuY catalysts are prepared by physically mixing CoMo/γ-Al2O3 catalyst with Cu-exchanged Y zeolite. The CuY zeolite is prepared by the solid state ion exchange technique. The thiophene hydrodesulfurization is performed in a fixed bed reactor at high temperature and atmospheric pressure. The results show that the presence of CuY zeolite particles in CoMo/Al2O3 catalyst can have a noticeable effect on both the conversion and product selectivities. An increasing zeolite loading in catalyst results in a decrease of the thiophene HDS activity. This decrease is probably caused by the formation of heavy compounds and the deactivation of the zeolite at high temperatures.

  5. Interlaboratory Study on the Determination of Crude Protein in Macaroni Products on JAS by Kjeldahl Method Using Copper Catalysts

    National Research Council Canada - National Science Library

    HAKODA, Akiko; II, Yusuke; SUZUKI, Tadanao; YASUI, Akemi

    2009-01-01

    The Kjeldahl method using copper catalysts for digestion was established as an analytical method for the determination of crude protein in macaroni products in the Japanese Agricultural Standard (JAS...

  6. A UV-Vis micro-spectroscopic study to rationalize the influence of Cl-(aq) on the formation of different Pd macro-distributions on Al2O3 catalyst bodies

    NARCIS (Netherlands)

    Espinosa-Alonso, L.; de Jong, K.P.|info:eu-repo/dai/nl/06885580X; Weckhuysen, B.M.|info:eu-repo/dai/nl/285484397

    2013-01-01

    The influence of the Cl (aq) concentration, solution pH and equilibration time on the PdCl4 2 (aq) dynamics and molecular structure after impregnation of g-Al2O3 catalyst bodies has been studied using UV-Vis micro-spectroscopy. To do so, 0.2 wt% Pd catalysts have been prepared from acidic solutions

  7. Session 6: Hydro-dechlorination of Carbon Tetrachloride: Study of the Deactivation and Regeneration of Pt Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Garetto, T.F.; Borgna, A. [Instituto de Investigaciones en Catalisis y Petroquimica-INCAPE. (UNL-CONICET), Santa Fe (Argentina); Montoya, J.A.; Acosta, D. [Zaragoza Univ., Dept. de Ingenieria Quimica y Tecnologias del Medio Ambiente. Facultad de Ciencias (Spain); Monzon, A. [Instituto Mexicano del Petroleo, D.F. (Mexico)

    2004-07-01

    The aim of this work is to get more insight on the deactivation-regeneration process of supported metal catalysts during CTC hydro-dechlorination. In this contribution we report a kinetic analysis on the deactivation-regeneration of Pt/Al{sub 2}O{sub 3} catalysts and the effect of the regeneration conditions. Particularly, the effectiveness of the regeneration treatment under different atmospheres is analyzed. (authors)

  8. Pelletization of catalysts supported on activated carbon. A Case Study : clean synthesis of dimethyl carbonate from methanol and CO2

    OpenAIRE

    Orrego Romero, Andrés Felipe; Arbeláez Pérez, Oscar Felipe; Bustamante Londoño, Felipe; Villa Holguín, Aída Luz

    2016-01-01

    The synthesis of Cu-Ni bimetallic catalyst supported on pellets of activated carbon using carboxymethylcellulose (CMC) as a binder is reported. The effect of preparation conditions, such as binder concentration, AC/binder ratio, temperature, and pyrolysis heating rate on the surface area of the pellets, was evaluated. Cu and Ni metals were incorporated on the pellets by conventional incipient wetness impregnation. The support and the synthesized catalysts were characterized using N2 adsorptio...

  9. Waste catalysts for waste polymer.

    Science.gov (United States)

    Salmiaton, A; Garforth, A

    2007-01-01

    Catalytic cracking of high-density polyethylene (HDPE) over fluid catalytic cracking (FCC) catalysts (1:6 ratio) was carried out using a laboratory fluidized bed reactor operating at 450 degrees C. Two fresh and two steam deactivated commercial FCC catalysts with different levels of rare earth oxide (REO) were compared as well as two used FCC catalysts (E-Cats) with different levels of metal poisoning. Also, inert microspheres (MS3) were used as a fluidizing agent to compare with thermal cracking process at BP pilot plant at Grangemouth, Scotland, which used sand as its fluidizing agent. The results of HDPE degradation in terms of yield of volatile hydrocarbon product are fresh FCC catalysts>steamed FCC catalysts approximately used FCC catalysts. The thermal cracking process using MS3 showed that at 450 degrees C, the product distribution gave 46 wt% wax, 14% hydrocarbon gases, 8% gasoline, 0.1% coke and 32% nonvolatile product. In general, the product yields from HDPE cracking showed that the level of metal contamination (nickel and vanadium) did not affect the product stream generated from polymer cracking. This study gives promising results as an alternative technique for the cracking and recycling of polymer waste.

  10. Foundation Flash Catalyst

    CERN Document Server

    Goralski, Greg

    2010-01-01

    This book offers an introduction to Flash Catalyst for designers with intermediate to advanced skills. It discusses where Catalyst sits within the production process and how it communicates with other programs. It covers all of the features of the Flash Catalyst workspace, teaching you how to create designs from scratch, how to build application designs and add functionality, and how to master the Catalyst/Flex workflow. * Introduces Flash Catalyst * Focuses on production process * Covers the interrelation between Flash Catalyst and Photoshop/Illustrator/Flex/Flash What you'll learn Starting f

  11. Ziegler-Natta Catalysts

    Directory of Open Access Journals (Sweden)

    G. Pircheraghi

    2007-12-01

    Full Text Available The effects of temperature, time and the strategy of prepolymerization were studied on the morphology of polypropylene particles. propylene polymerization was carried out in slurry phase using 4th generation of Ziegler-Natta Catalyst, cyclohexylmethyl dimethoxysilane as external electron donor, and triethyl aluminum as co-catalyst. Prepolymerizations 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 prepolymerization, 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 prepolymerization produced different morphological types. In all experiments coreshell structures were observed that seemed to be related to the structure of catalysts.

  12. Controlling the catalyst during carbon nanotube growth.

    Science.gov (United States)

    Robertson, J; Hofmann, S; Cantoro, M; Parvez, A; Ducati, C; Zhong, G; Sharma, R; Mattevi, C

    2008-11-01

    We have recently been able to grow single-walled carbon nanotubes by purely thermal chemical vapour deposition (CVD) at temperatures as low as 400 degrees C. This has been achieved by separating the catalyst pre-treatment step from the growth step. In the pre-treatment step, a thin film catalyst is re-arranged into a series of nano-droplets, which are then the active catalysts. Both steps have been studied by in-situ environmental transmission electron microscopy and X-ray photoemission spectroscopy. We have also studied the catalyst yield, the weight of nanotubes grown per weight of transition metal catalyst. Using very thin layers of Fe on Al2O3 support in a remote plasma-assisted CVD, we have achieved yields of order 100,000. This may be due to control of catalyst poisoning by ensuring an etching path.

  13. Spectroelectrochemical Study of Carbon Monoxide and Ethanol Oxidation on Pt/C, PtSn(3:1/C and PtSn(1:1/C Catalysts

    Directory of Open Access Journals (Sweden)

    Rubén Rizo

    2016-09-01

    Full Text Available PtSn-based catalysts are one of the most active materials toward that contribute ethanol oxidation reaction (EOR. In order to gain a better understanding of the Sn influence on the carbon monoxide (principal catalyst poison and ethanol oxidation reactions in acidic media, a systematic spectroelectrochemical study was carried out. With this end, carbon-supported PtSnx (x = 0, 1/3 and 1 materials were synthesized and employed as anodic catalysts for both reactions. In situ Fourier transform infrared spectroscopy (FTIRS and differential electrochemical mass spectrometry (DEMS indicate that Sn diminishes the amount of bridge bonded CO (COB and greatly improves the CO tolerance of Pt-based catalysts. Regarding the effect of Sn loading on the EOR, it enhances the catalytic activity and decreases the onset potential. FTIRS and DEMS analysis indicate that the C-C bond scission occurs at low overpotentials and at the same potential values regardless of the Sn loading, although the amount of C-C bond breaking decreases with the rise of Sn in the catalytic material. Therefore, the elevated catalytic activity toward the EOR at PtSn-based electrodes is mainly associated with the improved CO tolerance and the incomplete oxidation of ethanol to form acetic acid and acetaldehyde species, causing the formation of a higher amount of both C2 products with the rise of Sn loading.

  14. Study of the productivity of MWCNT over Fe and Fe–Co catalysts supported on SiO2, Al2O3 and MgO

    Directory of Open Access Journals (Sweden)

    S.A. Shokry

    2014-06-01

    Full Text Available In the present study, multi-walled carbon nanotubes (MWCNT were prepared in good quality and quantity, MWCNT were produced using the catalytic chemical vapor deposition (CCVD technique and the carbon source was acetylene. Different catalysts were synthesized based on iron and a mixture of iron and cobalt metal supported on SiO2, Al2O3 or MgO. The effect of parameters such as iron concentration, support type, bimetallic catalyst and the method of catalyst preparation has been investigated in the production of MWCNT. The quality of as-made nanotubes was investigated by the high-resolution transmission electron microscopy (HRTEM and thermogravimetric analysis (TGA. The best yield of MWCNT was 30 times of the amount of the used catalyst. The high yield of MWCNT was gained by 40 wt.% Fe on alumina support which was prepared by the sol–gel method. TEM analysis was done for the carbon deposit, which revealed that the walls of the MWCNT were graphitized, with regular inner channel and uniform diameter. It reflected a reasonable degree of purity. The TGA showed that MWCNT was decomposed at 635 °C by a small rate indicating a high thermal stability and well crystalline formation of the produced MWCNT.

  15. Support structure effect on CO oxidation: A comparative study on SiO2 nanospheres and CeO2 nanorods supported CuOx catalysts

    Science.gov (United States)

    Hossain, Shaikh Tofazzel; Almesned, Yazeed; Zhang, Kefu; Zell, Elizabeth T.; Bernard, David T.; Balaz, Snjezana; Wang, Ruigang

    2018-01-01

    The effect of support reducibility and reduction treatment was studied in SiO2 nanospheres and CeO2 nanorods supported CuOx (0 ≤ x ≤ 1) catalysts on CO oxidation. CuO nanoparticles were impregnated on SiO2 nanospheres and CeO2 nanorods using thermal decomposition method and then the samples were oxidized in air at different temperatures (400-600 °C). The sample oxidized at 400 °C was also further reduced under hydrogen atmosphere to compare the effect of reduction treatment on the catalytic activity. Detailed XRD, Raman, H2-TPR, and CO oxidation analyses were carried out to understand the effect of CuOx-support interaction and different CuOx species on the catalytic performance. Compared to SiO2 nanospheres supported CuOx catalysts, both CuO/CeO2 and reduced CuOx/CeO2 catalysts exhibited superior catalytic performance in terms of CO conversion and low-temperature hydrogen consumption. The enhanced activity of CeO2 nanorods supported CuOx catalysts was correlated strongly to the surface defects on CeO2 nanorods and interfacial structures.

  16. Molecular catalysts structure and functional design

    CERN Document Server

    Gade, Lutz H

    2014-01-01

    Highlighting the key aspects and latest advances in the rapidly developing field of molecular catalysis, this book covers new strategies to investigate reaction mechanisms, the enhancement of the catalysts' selectivity and efficiency, as well as the rational design of well-defined molecular catalysts. The interdisciplinary author team with an excellent reputation within the community discusses experimental and theoretical studies, along with examples of improved catalysts, and their application in organic synthesis, biocatalysis, and supported organometallic catalysis. As a result, readers wil

  17. In situ study of atomic structure transformations of Pt-Ni nanoparticle catalysts during electrochemical potential cycling.

    Science.gov (United States)

    Tuaev, Xenia; Rudi, Stefan; Petkov, Valeri; Hoell, Armin; Strasser, Peter

    2013-07-23

    When exposed to corrosive anodic electrochemical environments, Pt alloy nanoparticles (NPs) undergo selective dissolution of the less noble component, resulting in catalytically active bimetallic Pt-rich core-shell structures. Structural evolution of PtNi6 and PtNi3 NP catalysts during their electrochemical activation and catalysis was studied by in situ anomalous small-angle X-ray scattering to obtain insight in element-specific particle size evolution and time-resolved insight in the intraparticle structure evolution. Ex situ high-energy X-ray diffraction coupled with pair distribution function analysis was employed to obtain detailed information on the atomic-scale ordering, particle phases, structural coherence lengths, and particle segregation. Our studies reveal a spontaneous electrochemically induced formation of PtNi particles of ordered Au3Cu-type alloy structures from disordered alloy phases (solid solutions) concomitant with surface Ni dissolution, which is coupled to spontaneous residual Ni metal segregation during the activation of PtNi6. Pt-enriched core-shell structures were not formed using the studied Ni-rich nanoparticle precursors. In contrast, disordered PtNi3 alloy nanoparticles lose Ni more rapidly, forming Pt-enriched core-shell structures with superior catalytic activity. Our X-ray scattering results are confirmed by STEM/EELS results on similar nanoparticles.

  18. Calcium manganese oxides as oxygen evolution catalysts: O2 formation pathways indicated by 18O-labelling studies.

    Science.gov (United States)

    Shevela, Dmitriy; Koroidov, Sergey; Najafpour, M Mahdi; Messinger, Johannes; Kurz, Philipp

    2011-05-02

    Oxygen evolution catalysed by calcium manganese and manganese-only oxides was studied in (18)O-enriched water. Using membrane-inlet mass spectrometry, we monitored the formation of the different O(2) isotopologues (16)O(2), (16)O(18)O and (18)O(2) in such reactions simultaneously with good time resolution. From the analysis of the data, we conclude that entirely different pathways of dioxygen formation catalysis exist for reactions involving hydrogen peroxide (H(2)O(2)), hydrogen persulfate (HSO(5)(-)) or single-electron oxidants such as Ce(IV) and [Ru(III) (bipy)(3)](3+) . Like the studied oxide catalysts, the active sites of manganese catalase and the oxygen-evolving complex (OEC) of photosystem II (PSII) consist of μ-oxido manganese or μ-oxido calcium manganese sites. The studied processes show very similar (18)O-labelling behaviour to the natural enzymes and are therefore interesting model systems for in vivo oxygen formation by manganese metalloenzymes such as PSII. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Comparative study on cubic and tetragonal CexZr1-xO2 supported MoO3-catalysts for sulfur-resistant methanation

    Science.gov (United States)

    Liu, Zhaopeng; Xu, Yan; Cheng, Jiaming; Wang, Weihan; Wang, Baowei; Li, Zhenhua; Ma, Xinbin

    2018-03-01

    In this paper, two kinds of CexZr1-xO2 solid solution carriers with different Ce/Zr ratio were prepared by one-step co-precipitation method: the cubic Ce0.8Zr0.2O2 and the tetragonal Ce0.2Zr0.8O2 support. The MoO3/Ce0.8Zr0.2O2 and MoO3/Ce0.2Zr0.8O2 catalysts were prepared by incipient wetness impregnation method for comparative study on sulfur-resistant methanation reaction. The N2 adsorption/desorption, X-ray diffraction (XRD), Raman spectroscopy (RS), X-ray photoelectron (XPS), transmission electron microscopy (TEM), temperature-programmed reduction by hydrogen (H2-TPR) were undertaken to characterize the physico-chemical properties of the samples. The results indicated that the prepared MoO3/CexZr1-xO2 catalysts have a mesoporous structure with high surface area and uniform pore size distribution, achieving good MoO3 dispersion on CexZr1-xO2 supports. As for the catalytic performance of sulfur-resistant methanation, the cubic MoO3/Ce0.8Zr0.2O2 exhibited better than the tetragonal MoO3/Ce0.2Zr0.8O2 catalyst at reaction temperature 400 °C and 450 °C. CO conversion on the cubic MoO3/Ce0.8Zr0.2O2 catalyst was 50.1% at 400 °C and 75.5% at 450 °C, which is respectively 7% and 20% higher than that on the tetragonal MoO3/Ce0.2Zr0.8O2 catalyst. These were mainly attributed to higher content of active MoS2 on the surface of catalyst, the enhanced oxygen mobility, increased Mo-species dispersion as well as the excellent reducibility resulted from the increased amount of the reducible Ce3+ on the cubic MoO3/Ce0.8Zr0.2O2 catalyst.

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

    KAUST Repository

    Al-Khattaf, Sulaiman

    2008-11-19

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

  1. Photocatalytic water reduction and study of the formation of Fe(i)Fe(0) species in diiron catalyst systems.

    Science.gov (United States)

    Li, Xueqiang; Wang, Mei; Chen, Lin; Wang, Xiuna; Dong, Jingfeng; Sun, Licheng

    2012-05-01

    Noble-metal-free systems with bio-inspired diiron dithiolate mimics of the [FeFe]-hydrogenase active site, namely, [(μ-pdt)Fe(2) (CO)(5) L] [pdt=propanedithiolate; L=P(CH(2) OH)(3) (1), P(CH(3) )(3) (2)], as water reduction catalysts with xanthene dyes as photosensitizers and triethylamine as a sacrificial electron donor were studied for visible-light-driven water reduction to hydrogen. These systems display good catalytic activities with the efficiencies in hydrogen evolution of up to 226 turnovers for 1, if Eosin Y was used as the photosensitizer in an environmentally benign solvent (EtOH/H(2) O) after 15 h of irradiation (λ>450 nm) under optimal conditions. Under all of the conditions adopted, 1 that has a water soluble phosphine ligand, P(CH(2) OH)(3) displayed a higher efficiency than 2, which bears a PMe(3) ligand. The photoinduced electron transfer in the systems was studied using fluorescence, transient absorption, time-resolved UV/Vis, and in situ electron paramagnetic resonance (EPR) spectroscopy. A new electron-transfer mechanism is proposed for hydrogen evolution by these iron-based photocatalytic systems. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Climate change vulnerability assessments as catalysts for social learning: four case studies in south-eastern Australia

    Energy Technology Data Exchange (ETDEWEB)

    Preston, Benjamin L [ORNL

    2012-01-01

    Technical assessments of vulnerability and/or risk are increasingly being undertaken to assess the impacts of climate change. Underlying this is the belief that they will bring clarity to questions regarding the scale of institutional investments required, plausible adaptation policies and measures, and the timing of their implementation. Despite the perceived importance of technical assessments in 'evidence-based' decision environments, assessments cannot be undertaken independent of values and politics, nor are they capable of eliminating the uncertainty that clouds decision-making on climate adaptation As such, assessments can trigger as many questions as they answer, leaving practitioners and stakeholders to question their value. This paper explores the value of vulnerability/risk assessments in climate change adaptation planning processes as a catalyst for learning in four case studies in Southeastern Australia. Data were collected using qualitative interviews with stakeholders involved in the assessments and analysed using a social learning framework. This analysis revealed that detailed and tangible strategies or actions often do not emerge directly from technical assessments. However, it also revealed that the assessments became important platforms for social learning. In providing these platforms, assessments present opportunities to question initial assumptions, explore multiple framings of an issue, generate new information, and galvanise support for collective actions. This study highlights the need for more explicit recognition and understanding of the important role social learning plays in climate change vulnerability assessments and adaptation planning more broadly.

  3. Further studies of imido alkylidene complexes of tungsten, well-characterized olefin metathesis catalysts with controllable activity

    Energy Technology Data Exchange (ETDEWEB)

    Schrock, R.R.; DePue, R.T.; Feldman, J.; Yap, K.B.; Yang, D.C.; Davis, W.M.; Park, L.; DiMare, M.; Schofield, M.; Anhaus, J. (Massachusetts Institute of Technology, Cambridge (USA)); Walborsky, E.; Evitt, E. (Catalytica Inc., Mountain View, CA (USA)); Krueger, C.; Betz, P. (Max-Planck-Institute fuer Kohlenforschung, Ruhr (West Germany))

    1990-08-01

    An alternative synthesis of W(CH-t-Bu)(NAr)(dme)Cl{sub 2} (Ar = 2,6-C{sub 6}-H{sub 3}-i-Pr{sub 2}) consists of the five steps WCl{sub 6} {yields} W(O)Cl{sub 4} {yields} W(NAr)Cl{sub 4} {yields} W(NAr)(O-t-Bu){sub 2}Cl{sub 2}(THF) {yields} W(NAr)(O-t-Bu){sub 2}(CH{sub 2}-t-Bu){sub 2} {yields} W(CH-t-Bu)(NAr)(dme)Cl{sub 2}, in which tert-butoxide protecting groups are replaced by chlorides in the last step upon addition of PCl{sub 5}. The easiest synthesis to a catalyst precursor consists of the three steps WO{sub 2}Cl{sub 2} {yields} W(NAr){sub 2}Cl{sub 2}(dme) {yields} W(NAr){sub 2}(CH{sub 2}R){sub 2} {yields} W(CHR)(NAr)(OTf){sub 2}(dme) (R = t-Bu, CMe{sub 2}Ph; OTf = OSO{sub 2}CF{sub 3}), in which an imido ligand protecting group is ultimately replaced by two triflate ligands upon addition of triflic acid in the last step. An X-ray study of W(CH-t-Bu)(NAr)(O-t-Bu){sub 2} shows it to be a pseudotetrahedral complex in which the tert-butyl group points toward the imido ligand.

  4. A study concerning the pretreatment of CNTs and its influence on the performance of NiB/CNTs amorphous catalyst

    Directory of Open Access Journals (Sweden)

    CHANG YUAN HU

    2006-11-01

    Full Text Available As prepared carbon nanotubes were pretreated with nitric acid (CNTs-HNO3 or ammonia (CNTs-NH3. Fourier transform infrared spectroscopy (FTIR measurements showed that the surface of the nanotubes was functionalized with carboxylic and hydroxyl functional groups after the acid treatment and that basic groups containing nitrogen, such as N–H and C–N, were introduced to the surface of the nanotubes after the ammonia treatment. X-Ray diffraction analysis implied that the nickel residue in the CNTs was effectively removed by acid treatment. However, the nickel residue was only partially eliminated by ammonia pretreatment. NiB amorphous catalysts supported on CNTs-HNO3 and CNTs-NH3 were prepared by the impregnation–chemical reduction method and characterized by transmission electron microscopy (TEM, as well as inductively coupled plasma (ICP spectroscopy and studied in the selective hydrogenation of acetylene. TEM measurements showed that a high density NiB particles of about 9 nm were homogeneously dispersed on the CNTs-NH3. However, NiB particles (13–23 nmwith amean size of 16 nm were scattered on the CNTs-HNO3. As a result, the activity and selectivity of NiB/CNTs-NH3 were higher than those of NiB/CNTs-HNO3 in the selective hydrogenation of acetylene.

  5. Interaction of NH3 with Cu-SSZ-13 Catalyst: A Complementary FTIR, XANES, and XES Study.

    Science.gov (United States)

    Giordanino, Filippo; Borfecchia, Elisa; Lomachenko, Kirill A; Lazzarini, Andrea; Agostini, Giovanni; Gallo, Erik; Soldatov, Alexander V; Beato, Pablo; Bordiga, Silvia; Lamberti, Carlo

    2014-05-01

    In the typical NH3-SCR temperature range (100-500 °C), ammonia is one of the main adsorbed species on acidic sites of Cu-SSZ-13 catalyst. Therefore, the study of adsorbed ammonia at high temperature is a key step for the understanding of its role in the NH3-SCR catalytic cycle. We employed different spectroscopic techniques to investigate the nature of the different complexes occurring upon NH3 interaction. In particular, FTIR spectroscopy revealed the formation of different NH3 species, that is, (i) NH3 bonded to copper centers, (ii) NH3 bonded to Brønsted sites, and (iii) NH4(+)·nNH3 associations. XANES and XES spectroscopy allowed us to get an insight into the geometry and electronic structure of Cu centers upon NH3 adsorption, revealing for the first time in Cu-SSZ-13 the presence of linear Cu(+) species in Ofw-Cu-NH3 or H3N-Cu-NH3 configuration.

  6. A kinetic study of plutonium dioxide dissolution in hydrochloric acid using iron (II) as an electron transfer catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Fife, K.W.

    1996-09-01

    Effective dissolution of plutonium dioxide has traditionally been accomplished by contact with strong nitric acid containing a small amount of fluoride at temperatures of {approximately} 100 C. In spite of these aggressive conditions, PuO{sub 2} dissolution is sometimes incomplete requiring additional contact with the solvent. This work focused on an alternative to conventional dissolution in nitric acid where an electron transfer catalyst, Fe(II), was used in hydrochloric acid. Cyclic voltammetry was employed as an in-situ analytical technique for monitoring the dissolution reaction rate. The plutonium oxide selected for this study was decomposed plutonium oxalate with > 95% of the material having a particle diameter (< 70 {micro}m) as determined by a scanning laser microscopy technique. Attempts to dry sieve the oxide into narrow size fractions prior to dissolution in the HCl-Fe(II) solvent system failed, apparently due to significant interparticle attractive forces. Although sieve splits were obtained, subsequent scanning laser microscopy analysis of the sieve fractions indicated that particle segregation was not accomplished and the individual sieve fractions retained a particle size distribution very similar to the original powder assemblage. This phenomena was confirmed through subsequent dissolution experiments on the various screen fractions which illustrated no difference in kinetic behavior between the original oxide assemblage and the sieve fractions.

  7. Dehydrogenation Kinetics and Modeling Studies of MgH2 Enhanced by Transition Metal Oxide Catalysts Using Constant Pressure Thermodynamic Driving Forces

    Directory of Open Access Journals (Sweden)

    Saidi Temitope Sabitu

    2012-06-01

    Full Text Available The influence of transition metal oxide catalysts (ZrO2, CeO2, Fe3O4 and Nb2O5 on the hydrogen desorption kinetics of MgH2 was investigated using constant pressure thermodynamic driving forces in which the ratio of the equilibrium plateau pressure (pm to the opposing plateau (pop was the same in all the reactions studied. The results showed Nb2O5 to be vastly superior to other catalysts for improving the thermodynamics and kinetics of MgH2. The modeling studies showed reaction at the phase boundary to be likely process controlling the reaction rates of all the systems studied.

  8. Part I: A Comparative Thermal Aging Study on the Regenerability of Rh/Al2O3 and Rh/CexOy-ZrO2 as Model Catalysts for Automotive Three Way Catalysts

    Directory of Open Access Journals (Sweden)

    Qinghe Zheng

    2015-10-01

    Full Text Available The rhodium (Rh component in automotive three way catalysts (TWC experiences severe thermal deactivation during fuel shutoff, an engine mode (e.g., at downhill coasting used for enhancing fuel economy. In a subsequent switch to a slightly fuel rich condition, in situ catalyst regeneration is accomplished by reduction with H2 generated through steam reforming catalyzed by Rh0 sites. The present work reports the effects of the two processes on the activity and properties of 0.5% Rh/Al2O3 and 0.5% Rh/CexOy-ZrO2 (CZO as model catalysts for Rh-TWC. A very brief introduction of three way catalysts and system considerations is also given. During simulated fuel shutoff, catalyst deactivation is accelerated with increasing aging temperature from 800 °C to 1050 °C. Rh on a CZO support experiences less deactivation and faster regeneration than Rh on Al2O3. Catalyst characterization techniques including BET surface area, CO chemisorption, TPR, and XPS measurements were applied to examine the roles of metal-support interactions in each catalyst system. For Rh/Al2O3, strong metal-support interactions with the formation of stable rhodium aluminate (Rh(AlO2y complex dominates in fuel shutoff, leading to more difficult catalyst regeneration. For Rh/CZO, Rh sites were partially oxidized to Rh2O3 and were relatively easy to be reduced to active Rh0 during regeneration.

  9. A DNP-supported solid-state NMR study of carbon species in fluid catalytic cracking catalysts.

    Science.gov (United States)

    Mance, Deni; van der Zwan, Johan; Velthoen, Marjolein E Z; Meirer, Florian; Weckhuysen, Bert M; Baldus, Marc; Vogt, Eelco T C

    2017-04-04

    A combination of solid-state NMR techniques supported by EPR and SEM-EDX experiments was used to localize different carbon species (coke) in commercial fluid catalytic cracking catalysts. Aliphatic coke species formed during the catalytic process and aromatic coke species deposited directly from the feedstock respond differently to dynamic nuclear polarization signal enhancement in integral and crushed FCC particles, indicating that aromatic species are mostly concentrated on the outside of the catalyst particles, whereas aliphatic species are also located on the inside of the FCC particles. The comparison of solid-state NMR data with and without the DNP radical at low and ambient temperature suggests the proximity between aromatic carbon deposits and metals (mostly iron) on the catalyst surface. These findings potentially indicate that coke and iron deposit together, or that iron has a role in the formation of aromatic coke.

  10. Kinetics studies of synthesis of biodiesel from waste frying oil using a heterogeneous catalyst derived from snail shell.

    Science.gov (United States)

    Birla, Ashish; Singh, Bhaskar; Upadhyay, S N; Sharma, Y C

    2012-02-01

    Waste frying oil was used to produce biodiesel using calcined snail shell as a heterogeneous base catalyst. Trans esterification reactions were carried out and the yield and conversion of the product were optimized by varying the methanol to oil molar ratio, catalyst amount, reaction temperature, and time. A biodiesel conversion of 99.58% was obtained with a yield of 87.28%. The reaction followed first order kinetics. The activation energy (E(A)) was 79kJ/mol and the frequency factor (A) was 2.98×10(10)min(-1). The fuel properties of the biodiesel were measured according to ASTM D 6751 and found to be within the specifications. Snail shell is a novel source for the production of heterogeneous base catalyst that can be successfully utilized for synthesis of biodiesel of high purity. Copyright © 2011 Elsevier Ltd. All rights reserved.

  11. Study of KOH/Al2O3 as heterogeneous catalyst for biodiesel production via in situ transesterification from microalgae.

    Science.gov (United States)

    Ma, Guixia; Hu, Wenrong; Pei, Haiyan; Jiang, Liqun; Ji, Yan; Mu, Ruimin

    2015-01-01

    Heterogeneous KOH/Al2O3 catalysts, synthesized by the wet impregnation method with different KOH loadings (20-40 wt%) and calcination temperatures from 400°C to 800°C, were used to produce biodiesel from Chlorella vulgaris biomass by in situ transesterification. The highest yield of biodiesel of 89.53±1.58% was achieved at calcination temperature of 700°C for 2 h and 35 wt% loading of KOH, and at the optimal reaction condition of 10 wt% of catalyst content, 8 mL/g of methanol to biomass ratio and at 60°C for 5 h. The characteristics of the catalysts were analysed by X-ray diffraction, scanning electron microscopy and Brunauer-Emmett-Teller.

  12. Study of NiMoS mixed phase from catalyst precursors in residue slurry-bed hydrocracking

    Science.gov (United States)

    Du, Juntao; Deng, Wenan; Li, Chuan; Zhang, Zailong; Sun, Qiang; Cao, Xiangpeng; Yang, Tengfei

    2017-03-01

    The evolution and role of NiMoS structures from catalyst precursors on residue hydrocracking was investigated. NiMoS mixed phase played important roles in unsupported catalyst and heavy oil development, such as synergy effect and coke inhibiting. The oil-soluble molybdenum naphthenate and nickel naphthenate were chosen as catalyst precursors. The mixtures of the precursor were compared to those of other monometallic oil-soluble precursor in an effort to evaluate the evolution and role of NiMoS phase in the slurry bed hydrocracking of heavy oil. The presence of NiMoS phase were characterized by X-ray diffraction (XRD), TEM and XPS. The series of tests in the slurry-phase reactor was to confirm the synergy effect of NiMoS mixed phase.

  13. Nickel removal from nickel-5,10,15,20-tetraphenylporphine using supercritical water in absence of catalyst: a basic study.

    Science.gov (United States)

    Mandal, Pradip Chandra; Wahyudiono; Sasaki, Mitsuru; Goto, Motonobu

    2011-03-15

    Reactions of nickel-5,10,15,20-tetraphenylporphine (Ni-TPP) were studied in supercritical water in the presence of toluene without the addition of any catalyst, H(2) or H(2)S that is called a green process. The objective of this study was to remove nickel from Ni-TPP, the most common metal compound present in heavy crude, in high extent at low reaction time. All experiments were carried out in an 8.8 mL batch reactor fabricated from hastelloy C-276. The ability of supercritical water (SCW) to remove nickel from Ni-TPP was studied at temperatures of 450-490 °C and water partial pressures of 25-35 MPa. Water partial pressure had no effect on overall conversion at temperatures of 450 °C and a reaction time of 60 min. The overall Ni-TPP conversion was 89.80%, a figure above that of previous catalytic studies. The percentage of nickel removal was estimated as a function of reaction time and temperature. It were temperature 490 °C and pressure 25 MPa at reaction time 90 min where 65.68% nickel were removed by the action of SCW and toluene, as a co-solvent. It was determined that Ni-TPP undergoes a series of reactions, ending in demetallation and ring fragmentation. The obtained results suggest that supercritical water has a capability to remove nickel from Ni-TPP. Copyright © 2011 Elsevier B.V. All rights reserved.

  14. Experimental and theoretical study about sulfur deactivation of Ni/ CeO{sub 2} and Rh/CeO{sub 2} catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Ocsachoque, Marco A., E-mail: ocmarco@quimica.unlp.edu.ar [Centro de Investigación y Desarrollo en Ciencias Aplicadas “Dr Jorge J. Ronco”, (CONICET, CCT La Plata), Departamento de Química, Facultad de Cs Exactas (UNLP), Calle 48 N° 257, 1900 La Plata (Argentina); Eugenio Russman, Juan I.; Irigoyen, Beatriz [Instituto de Tecnologías del Hidrógeno y Energías Sostenibles (ITHES), Departamento de Ingeniería Química, Facultad de Ingeniería (UBA), Buenos Aires (Argentina); Gazzoli, Delia [Dipartimento di Chimia, Universitá di Roma “La Sapienza”, Roma (Italy); González, María G. [Centro de Investigación y Desarrollo en Ciencias Aplicadas “Dr Jorge J. Ronco”, (CONICET, CCT La Plata), Departamento de Química, Facultad de Cs Exactas (UNLP), Calle 48 N° 257, 1900 La Plata (Argentina)

    2016-04-01

    Sulfur deactivation of Ni/CeO{sub 2} and Rh/CeO{sub 2} catalysts were examined through an experimental and theoretical study. These catalysts were characterized by N{sub 2} adsorption, X-ray diffraction, temperature programmed reaction, thermogravimetric analysis, Uv–visible spectroscopy and Raman spectroscopy, and tested under the methane dry reforming reaction in the presence of H{sub 2}S. On the other hand, different possible interactions of sulfur with Rh, Ni or surface sites of the CeO{sub 2} support were evaluated by performing energy calculations with the density functional theory (DFT). Overall, the results indicate that tolerance to sulfur of Rh/CeO{sub 2} catalyst is higher than that of Ni/CeO{sub 2} one. In this sense, TPR measurements show that reduction of CeO{sub 2} is promoted by the presence of Rh. This effect, probably caused by hydrogen spillover to CeO{sub 2} support during the reduction of RhO{sub x} species, could be linked to a high oxygen donation capacity of Rh/CeO{sub 2} catalysts. Accordingly, the O{sup 2−} species existing on Rh/CeO{sub 2} catalysts, revealed by Raman spectra of these samples, could favor sulfur oxidation and prevent Rh–S interactions. Likewise, the theoretical calculations show that desorption of S–O species from Rh/CeO{sub 2} system is more favorable than that from Ni/CeO{sub 2} one. Therefore, our experimental and theoretical study about sulfur deactivation of Ni and Rh supported on CeO{sub 2} allow us to postulate that Rh can help to desorb SO{sub x} species formed on the support, retarding sulfur poisoning of the Rh/CeO{sub 2} catalysts. - Highlights: • CeO{sub 2} support can act as a sacrifice trap decreasing sulfur poisoning. • Theoretical calculations indicate an important nickel affinity with sulfur. • Rh would favor desorption of S–O species formed on the support. • The O{sup 2−} species present on the Rh–CeO{sub 2} sample favor sulfur removal.

  15. Design of heterogeneous catalysts

    DEFF Research Database (Denmark)

    Frey, Anne Mette

    was inspired by a computational screening, suggesting that alloys such as Ni-Fe, Co-Ni, and Co-Fe should show superior activity to the industrially used nickel catalyst. Especially the Ni-Fe system was considered to be interesting, since such alloy catalysts should be both more active and cheaper than the Ni....... Previously it has been shown that calcination of cobalt catalyst in a NO/He mixture resulted in improved catalytic activity compared to standard air calcined samples, since more homogenous cobalt particles with a narrow particle size distribution were formed. Unfortunately the C5+ selectivity decreased...... 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...

  16. World War I--Catalyst for the Creation of the Social Studies

    Science.gov (United States)

    Shermis, S. Samuel

    2009-01-01

    In honor of the 100th anniversary of "The Social Studies," the journal is reprinting this article, originally published in Vol. 55, No. 6 (November 1964). In this essay, Shermis explains that, while prior to 1914 the social studies did not exist, the field had come into existence within five years after World War I ended. The war, subsequent…

  17. Strengthening leadership as a catalyst for enhanced patient safety culture: a repeated cross-sectional experimental study.

    Science.gov (United States)

    Kristensen, Solvejg; Christensen, Karl Bang; Jaquet, Annette; Møller Beck, Carsten; Sabroe, Svend; Bartels, Paul; Mainz, Jan

    2016-05-13

    Current literature emphasises that clinical leaders are in a position to enable a culture of safety, and that the safety culture is a performance mediator with the potential to influence patient outcomes. This paper aims to investigate staff's perceptions of patient safety culture in a Danish psychiatric department before and after a leadership intervention. A repeated cross-sectional experimental study by design was applied. In 2 surveys, healthcare staff were asked about their perceptions of the patient safety culture using the 7 patient safety culture dimensions in the Safety Attitudes Questionnaire. To broaden knowledge and strengthen leadership skills, a multicomponent programme consisting of academic input, exercises, reflections and discussions, networking, and action learning was implemented among the clinical area level leaders. In total, 358 and 325 staff members participated before and after the intervention, respectively. 19 of the staff members were clinical area level leaders. In both surveys, the response rate was >75%. The proportion of frontline staff with positive attitudes improved by ≥5% for 5 of the 7 patient safety culture dimensions over time. 6 patient safety culture dimensions became more positive (increase in mean) (pleadership can act as a significant catalyst for patient safety culture improvement. Further studies using a longitudinal study design are recommended to investigate the mechanism behind leadership's influence on patient safety culture, sustainability of improvements over time, and the association of change in the patient safety culture measures with change in psychiatric patient safety outcomes. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  18. A Hard X-ray Study of a Manganese-Terpyridine Dimer Catalyst in a Chromium-based Metal Organic Framework - Oral Presentation

    Energy Technology Data Exchange (ETDEWEB)

    Ramsey, Alexandra [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-08-25

    Cleaner forms of energy are needed, and H2 produced from water spliFng is a possible source. However, a robust catalyst is necessary to carry out the water oxidaKon reacKon. Plants uKlize Photosystem II to catalyze water oxidaKon as a part of photosynthesis, and many syntheKc water oxidaKon catalysts use Photosystem II as a model. In this study, the catalyst of interest was [(terpy)Mn(μ-O)2Mn(terpy)]3+ (MnTD), which was synthesized in a chromium-based Metal Organic Framework (MOF) to avoid degradaKon of MnTD molecules. Hard X-ray powder diffracKon was the primary method of analysis. The diffracKon data was used to detect the presence of MOF in samples at different catalyKc stages, and laFce parameters were assigned to the samples containing MOF. Fourier maps were constructed to determine the contents of the MOF as preliminary studies suggested that MnTD may not be present. Results showed that MOF is present before catalysis occurs, but disappears in the iniKal stages of catalysis. Changes in the MOF’s laFce parameters suggest aWracKve interacKons between the MOF and catalyst; these interacKons may lead to the observed MOF degradaKon. Fourier maps also reveal limited, if any, amounts of MnTD in the system. Molecular manganese oxide may be the source of the high rate of water oxidaKon catalysis in the studied system.

  19. Experimental Studies on the Hydrotreatment of Kraft Lignin to Aromatics and Alkylphenolics Using Economically Viable Fe-Based Catalysts

    NARCIS (Netherlands)

    Agarwal, Shilpa; Chowdari, Ramesh Kumar; Hita, Idoia; Heeres, Hero Jan

    Limonite, a low-cost iron ore, was investigated as a potential hydrotreatment catalyst for kraft lignin without the use of an external solvent (batch reactor, initial H-2 pressure of 100 bar, 4 h). The best results were obtained at 450 degrees C resulting in 34 wt % of liquefied kraft lignin (lignin

  20. A study of Cu/ZnO/Al2O3 methanol catalysts prepared by flame combustion synthesis

    DEFF Research Database (Denmark)

    Jensen, Joakim Reimer; Johannessen, Tue; Wedel, Stig

    2003-01-01

    The flame combustion synthesis of Cu/ZnO/Al2O3 catalysts for the synthesis of methanol from CO, CO2 and H2 is investigated. The oxides are generated in a premixed flame from the acetyl-acetonate vapours of Cu, Zn and Al mixed with the fuel and air prior to combustion. The flame-generated powder...

  1. Genesis of Co/SiO2 catalysts : XAS study at the cobalt L-III,L- II absorption edges

    NARCIS (Netherlands)

    Bazin, D.; Kovacs, I.; Guczi, L.; Parent, P.; Laffon, C.; De Groot, F.; Ducreux, O.; Lynch, J.

    2000-01-01

    Silica-supported cobalt catalysts have been investigated by soft X-ray absorption techniques. Soft X-ray absorption spectra were collected at the Co LII,III edge during in situ reduction of calcined samples in a stream of hydrogen in the temperature range between 300 and 650°C. Using reference

  2. XPS and STEM Study of the Interface Formation between Ultra-Thin Ru and Ir OER Catalyst Layers and Perylene Red Support Whiskers

    Energy Technology Data Exchange (ETDEWEB)

    Atanasoska, Liliana [3M Industrial Mineral Products; Cullen, David A [ORNL; Hester, Amy E [3M Industrial Mineral Products; Atanasoski, Radoslav [3M Industrial Mineral Products

    2013-01-01

    The interface formation between perylene red (PR) and ruthenium or iridium OER catalysts has been studied systematically by XPS and STEM. The OER catalyst over-layers with thicknesses ranging from ~0.1 to ~50 nm were vapor deposited onto PR ex-situ. As seen by STEM, Ru and Ir form into nanoparticles, which agglomerate with increased loading. XPS data show a strong interaction between Ru and PR. Ir also interacts with PR although not to the extent seen for Ru. At low coverages, the entire Ru deposit is in the reacted state while a small portion of the deposited Ir remains metallic. Ru and Ir bonding occur at the PR carbonyl sites as evidenced by the attenuation of carbonyl photoemission and the emergence of new peak assigned to C-O single bond. The curve fitting analysis and the derived stoichiometry indicates the formation of metallo-organic bonds. The co-existence of oxide bonds is also apparent.

  3. Influence of the preparation procedure on the chemical and microstructural properties of lanthana promoted Rh/SiO{sub 2} catalysts. A FTIR spectroscopic study of chemisorbed CO

    Energy Technology Data Exchange (ETDEWEB)

    Bernal, S. [Cadiz Univ. (Spain). Facultad de Ciencias; Blanco, G. [Cadiz Univ. (Spain). Facultad de Ciencias; Calvino, J.J. [Cadiz Univ. (Spain). Facultad de Ciencias; Cauqui, M.A. [Cadiz Univ. (Spain). Facultad de Ciencias; Rodriguez-Izquierdo, J.M. [Cadiz Univ. (Spain). Facultad de Ciencias; Vidal, H. [Cadiz Univ. (Spain). Facultad de Ciencias

    1997-03-20

    In this work, the influence of the preparation procedure on the chemical and microstructural properties of a series of Rh/La{sub 2}O{sub 3}/SiO{sub 2} catalysts has been investigated. The catalysts were characterized by using HREM, H{sub 2} and CO volumetric adsorption and FTIR spectroscopy of chemisorbed CO. From our study, significant effects were observed for the following preparative variables: (a) the lanthana loading; (b) the way of introducing the metal and promoter, either consecutive (lanthana first and then the rhodium salt) or by co-impregnation; and (c) the calcination temperature (873 K or 1173 K) applied for preparing the La{sub 2}O{sub 3}/SiO{sub 2} intermediate phase onto which the noble metal was deposited. (orig.)

  4. The kinetics of the methanol synthesis on a copper catalyst: An experimental study

    NARCIS (Netherlands)

    Bos, A.N.R.; Borman, P.C.; Kuczynski, M.; Westerterp, K.R.

    1989-01-01

    The kinetics of the low pressure of methanol from feed gases containing solely CO and H2 were studied in an internally recycled gradientless reactor. As experimental accuracy impeded the application of high CO contents, the experimental range of mole fraction of CO was limited to 0.04 to 0.22. The

  5. Crotonaldehyde hydrogenation on Rh/TiO2 catalysts. In situ DRIFTS studies

    NARCIS (Netherlands)

    Reyes, P.; Aguirre, M. del C.; Melian Cabrera, Ignacio; Lopez Granados, M.; Fierro, J.L.G.

    2002-01-01

    The surface and catalytic properties in the vapor-phase hydrogenation of crotonaldehyde on Rh/TiO2 has been studied. It was found that a partial reduction of the support produces a surface decoration of the metal component. Thus, interfacial sites are created, which are responsible of an increase in

  6. A study of photocatalytic degradation of textile dye CI basic yellow 28 in water using P160 TiO2 based catalyst

    Directory of Open Access Journals (Sweden)

    Mijin Dušan

    2012-01-01

    Full Text Available The photocatalytic degradation of synthetic textile dye CI Basic Yellow 28 (BY28 in water, using recently synthesized P160 TiO2 based catalyst, under Osram ultra-vitalux® lamp (300 W light, was studied. The effect of the operational parameters such as initial concentration of catalyst, initial dye concentration and pH was studied. Salt effect was also investigated (NaCl, Na2CO3, Na2SO4, NaNO3. It was found that the optimal concentration of catalyst is 2.0 g L-1. A pseudo first-order kinetic model was illustrated using the Langmuir-Hinshelwood mechanism, and the adsorption equilibrium constant and the rate constant of the surface reaction were calculated (KBY = 6.126 L mg-1 and kC = 0.272 mg L-1 min-1, respectively. The photodegradation rate was higher in weak acidic than in high acidic and alkaline conditions. The presence of CO32- ions increases the photodegradation rate while Cl-, SO42- and NO3-ions decreases the reaction rate. The rate of photodegradation of BY28 was measured using UV-Vis spectroscopy. [Projekat Ministarstva nauke Republike Srbije, br. III 45019 and br. 172013.

  7. New insights in understanding plasma-catalysis reaction pathways: study of the catalytic ozonation of an acetaldehyde saturated Ag/TiO2/SiO2 catalyst

    Science.gov (United States)

    Sauce, Sonia; Vega-González, Arlette; Jia, Zixian; Touchard, Sylvain; Hassouni, Khaled; Kanaev, Andrei; Duten, Xavier

    2015-07-01

    This paper is a preliminary study intended to straighten out the role of reactive oxygen species in the activation mechanisms occurring in a plasma driven catalysis process for acetaldehyde decomposition. For this purpose, the interaction between the surface, the pollutant and one of the main oxidative species generated by non-thermal plasma, namely ozone, was studied. Acetaldehyde catalytic ozonation over a nanostructured Ag/TiO2/SiO2 catalyst is carried out at room temperature and atmospheric pressure, and followed by diffuse reflectance infrared fourier transform spectroscopy (DRIFTS). For this, the catalyst is firstly saturated with acetaldehyde. At the end of the saturation, acetaldehyde and crotonaldehyde, its condensation product, are identified as the major adsorbed species. In a second step, the surface ozonation is carried out and three additional intermediates are identified, namely, acetone, formic acid and acetic acid. Gaseous CO, CO2, methyl formate and methyl acetate are detected at the DRIFTS outlet, evidencing the partial mineralization of the adsorbed species. A global reaction scheme is proposed for explaining the formation of those adsorbed intermediates and gaseous products. This proposed heterogeneous ozone induced chemistry has to be taken into account when associating non-thermal plasma in air to a catalyst. Contribution to the topical issue "The 14th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XIV)", edited by Nicolas Gherardi, Ronny Brandenburg and Lars Stollenwark

  8. Experimental study on the nitrogen dioxide and particulate matter emissions from diesel engine retrofitted with particulate oxidation catalyst.

    Science.gov (United States)

    Feng, Xiangyu; Ge, Yunshan; Ma, Chaochen; Tan, Jianwei; Yu, Linxiao; Li, Jiaqiang; Wang, Xin

    2014-02-15

    A particulate oxidation catalyst (POC) was employed to perform experiments on the engine test bench to evaluate the effects on the nitrogen dioxide (NO2) and particulate matter (PM) emissions from diesel engine. The engine exhaust was sampled from both upstream and downstream of the POC. The results showed that the POC increased the ratios of NO2/NOx significantly in the middle and high loads, the ratio of NO2/nitrogen oxides (NOx) increased 4.5 times on average under all experiment modes with the POC. An engine exhaust particle sizer (EEPS) was used to study the particle number-weighted size distributions and the abnormal particle emissions with the POC. The results indicated that the average reduction rate of particle number (PN) was 61% in the operating range of the diesel engine. At the engine speed of 1,400 r/min, the reduction rates of PN tended to decrease with the larger particle size. In the long time run under the steady mode (520 Nm, 1,200 r/min), abnormal particle emissions after the POC happened seven times in the first hour, and the average PN concentration of these abnormal emission peaks was much higher than that in normal state. The particle emissions of peaks 1-5 equaled the particles emitted downstream of the POC in normal state for 1.9h in number concentration, and for 3.6h in mass concentration. The PN concentrations tended to increase over time in 5h under the steady engine mode and the increase of the PN in the size range of 6.04-14.3 nm was more evident. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. STUDY ON THE CONCENTRATION EFFECT OF Nb2O5-ZAA CATALYST TOWARDS TOTAL CONVERSION OF BIODIESEL IN TRANSESTERIFICATION OF WASTED COOKING OIL

    OpenAIRE

    Astuti Tri Padmaningsih; Wega Trisunaryanti; Iqmal Tahir

    2010-01-01

    Study on the concentration effect of Nb2O5-ZAA catalyst towards total conversion of biodiesel has been conducted. The natural zeolite (ZA) was activated by dipping in NH4Cl solution and was calcined using N2 atmosphere at 500 °C for 5h to produce the ZAA sample. The Nb2O5-ZAA catalyst was made by mixing the activated natural zeolite (ZAA), Nb2O5 3 % (w/w) and oxalic acid 10 % (w/w) solution, until the paste was formed, followed by drying and calcining the catalyst for 3 h at 500 °C under N2 a...

  10. Biochemical Studies of Mycobacterial Fatty Acid Methyltransferase: A Catalyst for the Enzymatic Production of Biodiesel.

    Science.gov (United States)

    Petronikolou, Nektaria; Nair, Satish K

    2015-11-19

    Transesterification of fatty acids yields the essential component of biodiesel, but current processes are cost-prohibitive and generate waste. Recent efforts make use of biocatalysts that are effective in diverting products from primary metabolism to yield fatty acid methyl esters in bacteria. These biotransformations require the fatty acid O-methyltransferase (FAMT) from Mycobacterium marinum (MmFAMT). Although this activity was first reported in the literature in 1970, the FAMTs have yet to be biochemically characterized. Here, we describe several crystal structures of MmFAMT, which highlight an unexpected structural conservation with methyltransferases that are involved in plant natural product metabolism. The determinants for ligand recognition are analyzed by kinetic analysis of structure-based active-site variants. These studies reveal how an architectural fold employed in plant natural product biosynthesis is used in bacterial fatty acid O-methylation. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Rapid Syphilis Tests as Catalysts for Health Systems Strengthening: A Case Study from Peru.

    Science.gov (United States)

    García, Patricia J; Cárcamo, César P; Chiappe, Marina; Valderrama, Maria; La Rosa, Sayda; Holmes, King K; Mabey, David C W; Peeling, Rosanna W

    2013-01-01

    Untreated maternal syphilis leads to adverse pregnancy outcomes. The use of point of care tests (POCT) offers an opportunity to improve screening coverage for syphilis and other aspects of health systems. Our objective is to present the experience of the introduction of POCT for syphilis in Peru and describe how new technology can catalyze health system strengthening. The study was implemented from September 2009-November 2010 to assess the feasibility of the use of a POCT for syphilis for screening pregnant women in Lima, Peru. Outcomes measured included access to syphilis screening, treatment coverage, partner treatment, effect on patient flow and service efficiency, acceptability among providers and patients, and sustainability. Before the introduction of POCT, a pregnant woman needed 6 visits to the health center in 27 days before she received her syphilis result. We trained 604 health providers and implemented the POCT for syphilis as the "two for one strategy", offering with one finger stick both syphilis and HIV testing. Implementation of the POCT resulted in testing and treatment on the first visit. Screening and treatment coverages for syphilis improved significantly compared with the previous year. Implementation of POCT has been scaled up nationally since the study ended, and coverages for screening, treatment and partner treatment have remained over 92%. Implementation of POCT for syphilis proved feasible and acceptable, and led to improvement in several aspects of health services. For the process to be effective we highlight the importance of: (1) engaging the authorities; (2) dissipating tensions between providers and identifying champions; (3) training according to the needs; (4) providing monitoring, supervision, support and recognition; (5) sharing results and discussing actions together; (6) consulting and obtaining feedback from users; and (7) integrating with other services such as with rapid HIV testing.

  12. Nanostructured Basic Catalysts: Opportunities for Renewable Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Conner, William C; Huber, George; Auerbach, Scott

    2009-06-30

    This research studied and developed novel basic catalysts for production of renewable chemicals and fuels from biomass. We focused on the development of unique porous structural-base catalysts zeolites. These catalysts were compared to conventional solid base materials for aldol condensation, that were being commercialized for production of fuels from biomass and would be pivotal in future biomass conversion to fuels and chemicals. Specifically, we had studied the aldolpyrolysis over zeolites and the trans-esterification of vegetable oil with methanol over mixed oxide catalysts. Our research has indicated that the base strength of framework nitrogen in nitrogen substituted zeolites (NH-zeolites) is nearly twice as strong as in standard zeolites. Nitrogen substituted catalysts have been synthesized from several zeolites (including FAU, MFI, BEA, and LTL) using NH3 treatment.

  13. Shock activation of catalysts

    Science.gov (United States)

    Graham, R. A.; Morosin, B.; Richards, P. M.; Stohl, F. V.; Granoff, B.

    1981-02-01

    Scientists in the Soviet Union have demonstrated that high pressure shock-wave loading can cause significant improvement in the performance of catalysts. This increased catalytic activity is apparently the result of the shock-induced defects, especially vacancies, which act to facilitate atomic migration. We have carried out shock activation experiments on a coal-derived pyrite which has been previously used as a catalyst in coal liquefaction studies. The pyrite powder was packed to a density of about 2.0 Mg/m3 in a copper capsule and explosively loaded to a pressure of about 15 GPa in the copper. The starting and shock-activated samples were analyzed by x-ray diffraction and magnetization measurements. The diffraction patterns of the shock-activated samples were dominated by broadened pyrite lines indicative of a significant increase in crystal defects. The diffraction patterns also showed the presence of pyrrhotite (Fe1-xS) in quantities of a few percent. An iron carbide found in the shocked material was apparently formed from carbon originating from either the calcite or organic impurities in the starting material. Magnetic properties of the sample were found to be substantially changed by the shock loading. The study has demonstrated that shock loading can significantly alter the crystalline order of pyrite and produce measurable quantities of pyrrhotite. The effects of shock-activated pyrite on the liquefaction of coal are being assessed by means by tubing reactor experiments.

  14. Study of Superbase-Based Deep Eutectic Solvents as the Catalyst in the Chemical Fixation of CO2 into Cyclic Carbonates under Mild Conditions

    Science.gov (United States)

    García-Argüelles, Sara; Iglesias, Marta; Del Monte, Francisco

    2017-01-01

    Superbases have shown high performance as catalysts in the chemical fixation of CO2 to epoxides. The proposed reaction mechanism typically assumes the formation of a superbase, the CO2 adduct as the intermediate, most likely because of the well-known affinity between superbases and CO2, i.e., superbases have actually proven quite effective for CO2 absorption. In this latter use, concerns about the chemical stability upon successive absorption-desorption cycles also merits attention when using superbases as catalysts. In this work, 1H NMR spectroscopy was used to get further insights about (1) whether a superbase, the CO2 adduct, is formed as an intermediate and (2) the chemical stability of the catalyst after reaction. For this purpose, we proposed as a model system the chemical fixation of CO2 to epichlorohydrin (EP) using a deep eutectic solvent (DES) composed of a superbase, e.g., 2,3,4,6,7,8-hexahydro-1H-pyrimido[1,2-a]pyrimidine (TBD) or 2,3,4,6,7,8,9,10-octahydropyrimido[1,2-a]azepine (DBU), as a hydrogen acceptor and an alcohol as a hydrogen bond donor, e.g., benzyl alcohol (BA), ethylene glycol (EG), and methyldiethanolamine (MDEA), as the catalyst. The resulting carbonate was obtained with yields above 90% and selectivities approaching 100% after only two hours of reaction in pseudo-mild reaction conditions, e.g., 1.2 bars and 100 °C, and after 20 h if the reaction conditions of choice were even milder, e.g., 1.2 bars and 50 °C. These results were in agreement with previous works using bifunctional catalytic systems composed of a superbase and a hydrogen bond donor (HBD) also reporting good yields and selectivities, thus confirming the suitability of our choice to perform this study. PMID:28773128

  15. Comparative Catalytic Evaluation of Nano-ZrOx Promoted Manganese Catalysts: Kinetic Study and the Effect of Dopant on the Aerobic Oxidation of Secondary Alcohols

    Directory of Open Access Journals (Sweden)

    Mohamed E. Assal

    2017-01-01

    Full Text Available This work reports the zirconia (ZrOx nanoparticles doped MnCO3 catalysts prepared by facile and simple coprecipitation technique and the synthesis of zirconia-manganese carbonate [X% ZrOx–MnCO3] (where X% = 0–7% catalyst which upon calcination at 400°C is converted to zirconia-manganese dioxide [1% ZrOx–MnO2] and when calcined at 500°C is converted to zirconia-manganic trioxide [1% ZrOx–Mn2O3]. A comparative catalytic study was performed to investigate the catalytic efficiency between carbonate and oxides for the selective oxidation of 1-phenylethanol by using molecular O2 as a clean oxidant. The influence of several parameters such as w/w% of ZrOx, reaction time, calcination temperature, catalyst amount, and reaction temperature has been thoroughly examined using oxidation of 1-phenylethanol as a model substrate. The 1% ZrOx–MnCO3 precalcined at 300°C exhibited the best catalytic efficiency. It was found that ZrOx nanoparticles also play an essential role in enhancing the effectiveness of the catalytic system for the aerobic oxidation of alcohols. Furthermore, the physical and chemical properties of synthesized catalysts were evaluated by microscopic and spectroscopic techniques. An extremely high specific activity of 40 mmol·g−1·h−1 with a 100% conversion of oxidation product and selectivity of >99% was achieved within extremely short reaction time (6 min.

  16. Study of Superbase-Based Deep Eutectic Solvents as the Catalyst in the Chemical Fixation of CO2 into Cyclic Carbonates under Mild Conditions

    Directory of Open Access Journals (Sweden)

    Sara García-Argüelles

    2017-07-01

    Full Text Available Superbases have shown high performance as catalysts in the chemical fixation of CO2 to epoxides. The proposed reaction mechanism typically assumes the formation of a superbase, the CO2 adduct as the intermediate, most likely because of the well-known affinity between superbases and CO2, i.e., superbases have actually proven quite effective for CO2 absorption. In this latter use, concerns about the chemical stability upon successive absorption-desorption cycles also merits attention when using superbases as catalysts. In this work, 1H NMR spectroscopy was used to get further insights about (1 whether a superbase, the CO2 adduct, is formed as an intermediate and (2 the chemical stability of the catalyst after reaction. For this purpose, we proposed as a model system the chemical fixation of CO2 to epichlorohydrin (EP using a deep eutectic solvent (DES composed of a superbase, e.g., 2,3,4,6,7,8-hexahydro-1H-pyrimido[1,2-a]pyrimidine (TBD or 2,3,4,6,7,8,9,10-octahydropyrimido[1,2-a]azepine (DBU, as a hydrogen acceptor and an alcohol as a hydrogen bond donor, e.g., benzyl alcohol (BA, ethylene glycol (EG, and methyldiethanolamine (MDEA, as the catalyst. The resulting carbonate was obtained with yields above 90% and selectivities approaching 100% after only two hours of reaction in pseudo-mild reaction conditions, e.g., 1.2 bars and 100 °C, and after 20 h if the reaction conditions of choice were even milder, e.g., 1.2 bars and 50 °C. These results were in agreement with previous works using bifunctional catalytic systems composed of a superbase and a hydrogen bond donor (HBD also reporting good yields and selectivities, thus confirming the suitability of our choice to perform this study.

  17. Study of preparation method and oxidization/reduction effect on the performance of nickel-cerium oxide catalysts for aqueous-phase reforming of ethanol

    Science.gov (United States)

    Roy, B.; Leclerc, C. A.

    2015-12-01

    The effect of preparation method and oxidation state of the active metal on the catalytic activity of Ni-Ce-O catalysts was studied for aqueous phase reforming of ethanol. A sol-gel (SG) route and a solution combustion synthesis (SCS) method were used for the preparation of 10 wt% Ni loaded catalysts. The catalytic activity of three groups of catalysts; reduced at 425 °C (HR, metallic Ni), reduced at 1000 °C (FR, metallic Ni), and not reduced (NR, as NiO) were tested at different operating conditions. The difference in the metal particle sizes, governed by the preparation method, affects the catalytic efficiency most, not the reduced or oxidized state of Ni. The SG samples were superior for ethanol conversion and selectivity for H2 and CO2 compared to the SCS samples. The X-ray photoelectron spectroscopy (XPS) analysis of the samples demonstrated that the relative ratio of Ce2O3 to CeO2 increased inside the reactor. While Ni doping increases oxygen mobility in the Ce-O lattice, Ce3+ converts Ni2+ to metallic Ni inside the reactor. This can explain why the reduction stage for Ni-Ce-O system in APR is irrelevant. Higher oxygen mobility through the support helps oxidation of CO to CO2 leading to improved catalytic performance.

  18. Supported metal catalysts for alcohol/sugar alcohol steam reforming.

    Science.gov (United States)

    Davidson, Stephen D; Zhang, He; Sun, Junming; Wang, Yong

    2014-08-21

    Despite extensive studies on hydrogen production via steam reforming of alcohols and sugar alcohols, catalysts typically suffer a variety of issues from poor hydrogen selectivity to rapid deactivation. Here, we summarize recent advances in fundamental understanding of functionality and structure of catalysts for alcohol/sugar alcohol steam reforming, and provide perspectives on further development required to design highly efficient steam reforming catalysts.

  19. Energetic Mapping of Ni Catalysts by Detailed Kinetic Modeling

    DEFF Research Database (Denmark)

    Bjørgum, Erlend; Chen, De; Bakken, Mari G.

    2005-01-01

    Temperature-programmed desorption (TPD) of CO has been performed on supported and unsupported nickel catalysts. The unsupported Ni catalyst consists of a Ni(14 13 13) single crystal which has been studied under ultrahigh vacuum conditions. The desorption energy for CO at low CO surface coverage w...... nicely with literature values, providing useful information for identifying active sites on supported Ni catalysts....

  20. 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.

  1. Ruthenium-based olefin metathesis catalysts bearing pH-responsive ligands: External control of catalyst solubility and activity

    Science.gov (United States)

    Balof, Shawna Lynn

    2011-12-01

    Sixteen novel, Ru-based olefin metathesis catalysts bearing pH responsive ligands were synthesized. The pH-responsive groups employed with these catalysts included dimethylamino (NMe2) modified NHC ligands as well as N-donor dimethylaminopyridine (DMAP) and 3-(o-pyridyl)propylidene ligands. These pH-responsive ligands provided the means by which the solubility and/or activity profiles of the catalysts produced could be controlled via acid addition. The main goal of this dissertation was to design catalyst systems capable of performing ring opening metathesis (ROMP) and ring closing metathesis (RCM) reactions in both organic and aqueous media. In an effort to quickly gain access to new catalyst structures, a template synthesis for functionalized NHC ligand precursors was designed, in addition to other strategies, to obtain ligand precursors with ancillary NMe2 groups. Kinetic studies for the catalysts produced from these precursors showed external control of catalyst solubility was afforded via protonation of the NMe2 groups of their NHC ligands. Additionally, this protonation afforded external control of catalyst propagation rates for several catalysts. This is the first known independent external control for the propagation rates of ROMP catalysts. The incorporation of pH-responsive N-donor ligands into catalyst structures also provided the means for the external control of metathesis activity, as the protonation of these ligands resulted in an increased initiation rate based on their fast and irreversible dissociation from the metal center. The enhanced external control makes these catalysts applicable to a wide range of applications, some of which have been explored by us and/or through collaboration. Three of the catalysts designed showed remarkable metathesis activity in aqueous media. These catalysts displayed comparable RCM activity in aqueous media to a class of water-soluble catalysts reported by Grubbs et al., considered to be the most active catalyst for

  2. 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....

  3. Theoretical investigations of olefin metathesis catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Cundari, T.R.; Gordon, M.S. [North Dakota State Univ., Fargo, ND (United States)

    1992-01-01

    An ab initio analysis of the electronic structure of high-valent, transition-metal alkylidenes as models for olefin metathesis catalysts is presented. The catalyst models studied fall into three categories: {open_quotes}new{close_quotes} metathesis catalyst models-tetrahedral M(OH){sup 2}(XH)(CH{sub 2}) complexes; {open_quotes}old{close_quotes} metathesis catalyst models-tetrahedral MCl{sub 2}(Y)(CH{sub 2}) complexes and alkylidene-substituted Mo metathesis catalysts, Mo(OH){sub 2}(NH)(=C(H)Z). The effect on the bonding caused by modification of either the metal, ligands, or alkylidene substitutents is considered. 21 refs., 2 figs., 5 tabs.

  4. Catalyst Architecture

    DEFF Research Database (Denmark)

    qualities, which we find interesting to study and to learn from. The projects have in common that they all connect, transform and set a new agenda in the given context. They all have public access and in most cases, they are also under public administration. Thus, we do not deal with shopping malls, office...... in Rio de Janeiro and Nørrebro in Copenhagen, but we do not examine the topic further. Case Studies in Transition Zones In the selection as well as the analysis of the projects, particular emphasis has been placed on their localization. There has been particular focus on transition zones between one...... on the analysis of the strategic cases, drawing conclusions by comparison across the cases is not immediately possible. The thematic summary in chapter 7 should therefore be read concurrently with the presentation of the individual cases. In this way, the empirical richness, which the analyses make available, can...

  5. Laser flash photolysis study of photocatalytic properties of pillared interlayered clays and Fe,Al-silica mesoporous catalysts.

    Science.gov (United States)

    Glebov, Evgeni M; Pozdnyakov, Ivan P; Grivin, Vjacheslav P; Plyusnin, Victor F; Bazhin, Nikolai M; Zhang, Xu; Wu, Feng; Timofeeva, Maria N

    2013-11-01

    Laser flash photolysis was applied to determine the primary photochemical processes over iron-containing clay (montmorillonite KSF), pillared interlayered clays (PILCs) and mesoporous mesophase iron silicate materials (MMMs). For KSF, the homogeneous photochemical reaction of Fe(III) leached from the clay material resulted in the formation of OH radicals, which were monitored by means of their reaction with methyl viologen dication (MV(2+)). For PILCs and MMMs, no leaching of Fe(III) to the solution nor hydroxyl radical formation were observed. Nevertheless, these catalysts were found to exhibit a sufficient effect on phenol photoionization. The increase in quantum yields of PhO radicals is caused by the effect of PILCs and MMMs and is explained by heterogeneous processes on the surface of catalyst particles.

  6. Comparative study of CuO-CeO{sub 2} catalysts prepared by wet impregnation and deposition-precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Gurbani, A.; Ayastuy, J.L.; Gonzalez-Marcos, M.P.; Gutierrez-Ortiz, M.A. [Departamento de Ingenieria Quimica, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Bilbao 48080 (Spain); Unidad Asociada ' ' Tecnologias Quimicas para la Sostenibilidad Ambiental' ' , CSIC-UPV/EHU (Spain); Herrero, J.E.; Guil, J.M. [Instituto de Quimica Fisica ' ' Rocasolano' ' - CSIC, Madrid 28006 (Spain); Unidad Asociada ' ' Tecnologias Quimicas para la Sostenibilidad Ambiental' ' , CSIC-UPV/EHU (Spain)

    2009-01-15

    Two different preparation methods are used to synthesize wt. 7% CuO-CeO{sub 2} catalysts: a conventional wet impregnation method, and a deposition-precipitation (DP) method using Na{sub 2}CO{sub 3} as precipitating agent. Both samples are characterized by a series of techniques. CuO-CeO{sub 2} (Cu-Ce) prepared by DP shows a lower capacity to release the lattice oxygen to form CO{sub 2}. From CO-TPR results, it is demonstrated that this catalyst is not able to reduce copper clusters at low temperatures. Also, CO-TPD shows no CO{sub 2} formation. The activity results confirm the worse performance of Cu-Ce prepared by DP especially when oxygen is not in excess (PROX reaction with stoichometric oxygen). A copper particle size which is too small could create a stronger metal-support interaction, with lower Cu-Ce interface to react. (author)

  7. Spectroscopy, microscopy and theoretical study of NO adsorption on MoS2 and Co-Mo-S hydrotreating catalysts

    DEFF Research Database (Denmark)

    Topsøe, Nan-Yu; Tuxen, Anders Kyrme; Hinnemann, Berit

    2011-01-01

    at the edge in the form of S-H groups. For such samples, the results indicate a "push-pull" type mechanism involving simultaneous vacancy creation, NO adsorption and H2S release. This mechanism is observed to dominate in the IR experiments. In STM experiments, stable vacancies can be generated by dosing......nfrared (IR) spectroscopy using NO as a probe molecule has been one of the important methods for characterizing hydrotreating catalysts, since this technique provides information on the nature and quantity of active edge sites of these catalysts. However, due to the strong adsorption of NO, which...... may lead to significant edge reconstructions, it has not been clear, how the characteristics of the adsorption complexes may reflect the nature of the original edge sites. By combining IR spectroscopy measurements with scanning tunneling microscopy (STM) experiments and density functional theory (DFT...

  8. DFT Study of Oxygen Reduction Reaction on Os/Pt Core−Shell Catalysts Validated by Electrochemical Experiment

    OpenAIRE

    Tsai, Ho-Cheng; Hsieh, Yu-Chi; Yu, Ted H.; Lee, Yi-Juei; Wu, Yue-Han; Merinov, Boris V.; Wu, Pu-Wei; Chen, San-Yuan; Adzic, Radoslav R.; Goddard, William A.

    2015-01-01

    Proton exchange membrane fuel cells (PEMFCs) have attracted much attention as an alternative source of energy with a number of advantages, including high efficiency, sustainability, and environmentally friendly operation. However, the low kinetics of the oxygen reduction reaction (ORR) restricts the performance of PEMFCs. Various types of catalysts have been developed to improve the ORR efficiency, but this problem still needs further investigations and improvements. In this paper, we propose...

  9. Fundamental Studies of Butane Oxidation over Model-Supported Vanadium Oxide Catalysts: Molecular Structure-Reactivity Relationships

    NARCIS (Netherlands)

    Wachs, I.E.; Jehng, J.M.; Deo, G.; Weckhuysen, B.M.; Guliants, V.V.; Benziger, J.B.; Sundaresan, S.

    1997-01-01

    The oxidation of n-butane to maleic anhydride was investigated over a series of model-supported vanadia catalysts where the vanadia phase was present as a two-dimensional metal oxide overlayer on the different oxide supports (TiO2, ZrO2, CeO2, Nb2O5, Al2O3, and SiO2). No correlation was found

  10. Insight on the silver catalyst distribution during silicon nanowire array formation: an X-ray reflectivity study.

    Science.gov (United States)

    Kremenak, Jesse W; Arendse, Christopher J; Cummings, Franscious R; Chen, Yiyao; Miceli, Paul F

    2017-12-14

    Although metal-catalysts are commonly used to create nanoscale materials at surfaces, little is quantitatively known or understood about the depth distribution profile of the catalyst during the growth process. Using X-ray reflectivity, we report the first quantitative investigation, with nanoscale resolution, of the Ag metal-catalyst depth distribution profile during metal-assisted chemical etch (MACE) growth of Si nanowire (SiNW) arrays on Si(100). Given the very low optical reflectivity of these nanowire arrays, specular reflection from these materials in the X-ray region is extremely challenging to measure because it probes interfaces on the nanoscale. Nevertheless, we demonstrate that with suitable investigation, X-ray specular reflection can be measured and utilized to obtain unique structural information about the composition profile of both Ag and Si. The measurements, which also include X-ray diffraction and complementary electron microscopy, reveal that the Ag nanoparticles distribute along the length of the nanowires upon etching with a Ag density that increases towards the etch front. The Ag nanoparticles coarsen with etch time, indicating a high mobility of Ag ions even though we also find that the Ag does not migrate from the SiNW region into the etch bath during etching. The Ag density gradient and the Ag mobility suggest the existence of a strong chemical force that attracts Ag towards the etch front. These results provide unique and important new insight into the growth process for creating SiNWs from wet chemical etching using metal-catalysts.

  11. Studies of CO oxidation on Pt/SnO2 catalyst in a surrogate CO2 laser facility

    Science.gov (United States)

    Batten, Carmen E.; Miller, Irvin M.; Paulin, Patricia A.; Schryer, Jacqueline

    1987-01-01

    Samples of 1% Pt/SnO2 catalyst were exposed to a stoichiometric gas mixture of 1% CO and 1.2% O2 in helium over a range of flowrates from 5 to 15 sccm and temperatures from 338 to 394 Kelvin. Reaction rate constants for the catalytic oxidation of carbon monoxide and their temperature dependence were determined and compared with previous literature values.

  12. A study on pyrolysis of Canada thistle (Cirsium arvense) with titania based catalysts for bio-fuel production.

    Science.gov (United States)

    Aysu, Tevfik

    2016-11-01

    The catalytic pyrolysis of Cirsium arvense was performed with titania supported catalysts under the operating conditions of 500°C, 40°C/min heating rate, 100mL/min N2 flow rate in a fixed bed reactor for biofuel production. The effect of catalysts on product yields was investigated. The amount of pyrolysis products (bio-char, bio-oil, gas) and the composition of the produced bio-oils were determined by proton nuclear magnetic resonance ((1)H NMR), Fourier transform infrared spectroscopy (FT-IR), gas chromatography/mass spectrometry (GC-MS) and elemental analysis (EA) techniques. Thistle bio-oils had lower O/C and H/C molar ratios compared to feedstock. The highest bio-char and bio-oil yields of 29.32wt% and 36.71wt% were obtained in the presence of Ce/TiO2 and Ni/TiO2 catalysts respectively. GC-MS identified 97 different compounds in the bio-oils obtained from thistle pyrolysis. (1)H NMR analysis showed that the bio-oils contained ∼55-77% aliphatic and ∼6-19% aromatic structural units. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. 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.

  14. Hydroxide catalysts for lignin depolymerization

    Science.gov (United States)

    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.

  15. Solid-State (31)P Magic Angle Spinning (MAS) NMR Study of the Partitioning and Reaction of Organophosphorus Esters Adsorbed on Synthetic Resin Catalysts

    Science.gov (United States)

    1992-09-01

    AND REACTION OF ORGANOPHOSPHORUS ESTERS ADSORBED ON SYNTHETIC RESIN CATALYSTS William T. Beaudry George W. Wagner J. Richard Ward RESEARCH...Partitioning and Reaction of Orqanophosphorus PR-10161102A71A Esaters Adsorbed on Synthetic Resin Catalysts 6. AUTHOR(S) Beaudry, William T., Wagner...PARTITIONING AND REACTION OF ORGANOPHOSPHORUS ESTERS ADSORBED ON SYNTHETIC RESIN CATALYSTS 1. INTRODUCTION Characterizing chemical reactions on synthetic

  16. Reducible oxide based catalysts

    Science.gov (United States)

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

    2010-04-06

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

  17. Fischer-Tropsch Catalysts

    Science.gov (United States)

    White, James H. (Inventor); Taylor, Jesse W. (Inventor)

    2008-01-01

    Catalyst compositions and methods for F-T synthesis which exhibit high CO conversion with minor levels (preferably less than 35% and more preferably less than 5%) or no measurable carbon dioxide generation. F-T active catalysts are prepared by reduction of certain oxygen deficient mixed metal oxides.

  18. 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...

  19. 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.

  20. FY 1997 report on the development of excellent catalysts for creation of new industries. New frontier catalyst 21; 1997 nendo chosa hokokusho (shinsangyo sosei no tame no excellence catalyst no kaihatsu). New frontier catalyst 21

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    Survey was made for establishment of an effective fast search technique of practical catalysts. Catalyst technology is an important basic technology for industrial fields such as energy and environment fields. In many cases, catalysts have been developed by trial and error consuming a long time and huge research cost. Study was made on efficient analysis and measurement techniques, and systematic production technique of advanced catalysts based on these techniques. This survey was effective in finding a guidance for improving catalysts used in the previous processes, and facilitating searches for fields previously slow in development of catalysts. Advanced catalysts possible to actively selectively produce target products under high pressure/temperature conditions are much in demand. Recently in-situ analysis technology for observing molecules and material surfaces under ultrahigh-pressure/temperature conditions has been studied. Observational study was made on catalytic behavior under catalytic reaction condition using partial oxidation, selective hydrogenation and isomerization as model reactions. 111 refs., 103 figs., 9 tabs.

  1. Oxidative conversion of light alkanes to olefins over alkali promoted oxide catalysts.

    NARCIS (Netherlands)

    Leveles, L.; Fuchs, S.; Fuchs, Stefan; Seshan, Kulathuiyer; Lercher, J.A.; Lefferts, Leonardus

    2002-01-01

    Alkali promoted mixed oxides were studied as catalysts for the oxidative dehydrogenation (ODH) and cracking of butane and propane. Olefin yields as high as 50% were obtained with Li/MgO-based catalysts. Magnesia-based catalysts showed higher activity for olefin production than catalysts based on

  2. A comparison study of toluene removal by two-stage DBD-catalyst systems loading with MnO(x), CeMnO(x), and CoMnO(x).

    Science.gov (United States)

    Huang, Yifan; Dai, Shaolong; Feng, Fada; Zhang, Xuming; Liu, Zhen; Yan, Keping

    2015-12-01

    This paper studies the toluene removal by a two-stage dielectric barrier discharge (DBD)-catalyst system with three catalysts: MnO(x)/ZSM-5, CoMnO(x)/ZSM-5, and CeMnO(x)/ZSM-5. V-Q Lissajous method, Brunauer-Emmett-Teller (BET) surface area, X-ray diffraction (XRD), and X-ray photoelectron (XPS) are used to characterize the DBD and catalysts. The DBD processing partially oxidizes the toluene, and the removal efficiency has a linear relationship with ozone generation. Three DBD-catalyst systems are compared in terms of their toluene removal efficiency, Fourier transform infrared (FTIR) spectra, carbon balance, CO selectivity, CO2 selectivity, and ozone residual. The results show that the DBD-catalyst system with CoMnO(x)/ZSM-5 performs better than the other two systems. It has the highest removal efficiency of about 93.7%, and the corresponding energy yield is 4.22 g/kWh. The carbon balance and CO2 selectivity of CoMnO(x)/ZSM-5 is also better than the other two catalysts. The measurements of two important byproducts including aerosols and ozone are also presented.

  3. A Simulation Study of Effect of Mn-Ce/γ-Al2O3 on NOx Storage and Reduction over Pt-Ce-Ba/γ-Al2O3 Catalysts

    Directory of Open Access Journals (Sweden)

    Lili Lei

    2016-01-01

    Full Text Available A series of Pt-Ce-Ba/γ-Al2O3 and Mn-Ce/γ-Al2O3 catalysts were synthesized by a sol-gel method and the samples were characterized by XRD, SEM, and EDS. The effect of Mn-Ce/γ-Al2O3 on the storage and reduction of NOx over Pt-Ce-Ba/γ-Al2O3 catalysts was studied in a fix-bed reactor with simulation gases NO, O2, and N2. The results indicated that NO oxidation to NO2 was reduced with the increase of inlet NO concentration, which was up to 83% when the concentration of NO was 500 ppm but reduced to 76% with the concentration of NO increasing to 1000 ppm. Comparing with the Pt-Ce-Ba/γ-Al2O3 catalysts, the rate of NOx storage and reduction was remarkably increased over Pt-Ce-Ba/γ-Al2O3 combined with Mn-Ce/γ-Al2O3 catalysts. However, the reductant used for NOx reduction reaction over Pt-Ce-Ba/γ-Al2O3 catalysts was consumed under the treatment of Mn-Ce/γ-Al2O3 catalyst, which caused the NOx conversion to obviously drop, but the rate of NOx absorption declined slightly.

  4. Carbon corrosion of proton exchange membrane fuel cell catalyst layers studied by scanning transmission X-ray microscopy

    Science.gov (United States)

    Hitchcock, Adam P.; Berejnov, Viatcheslav; Lee, Vincent; West, Marcia; Colbow, Vesna; Dutta, Monica; Wessel, Silvia

    2014-11-01

    Scanning Transmission X-ray Microscopy (STXM) at the C 1s, F 1s and S 2p edges has been used to investigate degradation of proton exchange membrane fuel cell (PEM-FC) membrane electrode assemblies (MEA) subjected to accelerated testing protocols. Quantitative chemical maps of the catalyst, carbon support and ionomer in the cathode layer are reported for beginning-of-test (BOT), and end-of-test (EOT) samples for two types of carbon support, low surface area carbon (LSAC) and medium surface area carbon (MSAC), that were exposed to accelerated stress testing with upper potentials (UPL) of 1.0, 1.2, and 1.3 V. The results are compared in order to characterize catalyst layer degradation in terms of the amounts and spatial distributions of these species. Pt agglomeration, Pt migration and corrosion of the carbon support are all visualized, and contribute to differing degrees in these samples. It is found that there is formation of a distinct Pt-in-membrane (PTIM) band for all EOT samples. The cathode thickness shrinks due to loss of the carbon support for all MSAC samples that were exposed to the different upper potentials, but only for the most aggressive testing protocol for the LSAC support. The amount of ionomer per unit volume significantly increases indicating it is being concentrated in the cathode as the carbon corrosion takes place. S 2p spectra and mapping of the cathode catalyst layer indicates there are still sulfonate groups present, even in the most damaged material.

  5. 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.

  6. Effects of Catalyst Variation on Biodiesel Yield

    OpenAIRE

    A. O. Adeodu

    2015-01-01

    The type, purity and amount of catalyst used affect the conversion efficiency of the transesterification process of converting oil to biodiesel. In this study, the effect of alkali and acid catalysts variation was examined on biodiesel yield. Sodium hydroxide at different concentration of 0.6-1.6% to unused oil was used as a catalyst for transesesterifying unused oil to biodiesel. The optimum biodiesel yield was achieved using 1.4 wt. % of NaOH to oil weight, which produced an 88.0% yield of ...

  7. The study of CaO and MgO heterogenic nano-catalyst coupling on transesterification reaction efficacy in the production of biodiesel from recycled cooking oil.

    Science.gov (United States)

    Tahvildari, Kambiz; Anaraki, Yasaman Naghavi; Fazaeli, Reza; Mirpanji, Sogol; Delrish, Elham

    2015-01-01

    Fossil fuels' pollution and their non-renewability have motivated the search for alternative fuels. Some common example of seed oils are sunflower oil, date seed oil, soy bean oil. For instance, soy methyl and soy-based biodiesel are the main biodiesel. Biodiesel is a clean diesel fuel that can be produced through transesterification reaction. Recycled cooking oil, on the other hand, is one of the inexpensive, easily available sources for producing biodiesel. This article is aimed at production of biodiesel via trans-esterification method, Nano CaO synthesis using sol-gel method, and Nano MgO synthesis using sol-gel self-combustion. Two catalysts' combination affecting the reaction's efficacy was also discussed. Optimum conditions for the reaction in the presence of Nano CaO are 1.5 % weight fracture, 1:7 alcohol to oil proportion and 6 h in which biodiesel and glycerin (the byproduct) are produced. Moreover, the optimum conditions for this reaction in the presence of Nano CaO and Nano MgO mixture are 3 % weight fracture (0.7 g of Nano CaO and 0.5 g of Nano MgO), 1:7 alcohols to oil proportion and 6 h. Nano MgO is not capable of catalyzing the transesterification by itself, because it has a much weaker basic affinity but when used with Nano CaO due to its surface structure, the basic properties increase and it becomes a proper base for the catalyst so that CaO contact surface increases and transesterification reaction yield significantly increases as well. This study investigates the repeatability of transesterification reaction in the presence of these Nano catalysts as well.

  8. Effect of Al content on the strength of terminal silanol species in ZSM-5 zeolite catalysts: a quantitative DRIFTS study without the use of molar extinction coefficients.

    Science.gov (United States)

    Bräuer, Pierre; Situmorang, Olivia; Ng, Pey Ling; D'Agostino, Carmine

    2018-02-07

    The strength of terminal hydroxyl Si-OH groups (silanols) in zeolites is important for many non-size-selective catalytic reactions occurring onto the external surface of the zeolite crystals and may often be responsible for catalyst deactivation, e.g., coke formation. A quantitative analysis of Si-OH strength and its link with the Al content, hence varying silica-to-alumina ratio (SAR = SiO2/Al2O3), has not been established yet. Various hypotheses have been proposed in the literature; nonetheless, the role of Al content in determining silanol strength remains still unclear and the object of speculation. In this work, we have systematically investigated the effect of the Al content on the strength of terminal silanol sites in ZSM-5 zeolite catalysts with varying SAR using Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) at variable temperatures without molar extinction coefficients. Two base probe molecules with different proton affinity values, pyridine and collidine, were used. To quantify the strength of terminal silanol sites the change of the terminal silanol peak in the OH stretching region, together with data on elemental analysis, was used. With this experimental protocol, unlike most IR studies, the use of molar extinction coefficients, often difficult to obtain, is not needed for quantification. The results reported here show for the first time that for ZSM-5 zeolite catalysts the fraction of occupied terminal silanol acid sites for both pyridine and collidine increases with increasing concentration of external Brønsted acid sites, hence establishing a clear link between the two types of acid sites. In summary, this work shows that the use of DRIFTS without molar extinction coefficients is able to quantitatively probe the strength of terminal silanol acid sites and establishes a link between the external Brønsted Al content and the strength of terminal silanol species in ZSM-5 zeolites with varying SAR at elevated temperatures.

  9. 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

  10. ALKALI RESISTANT CATALYST

    DEFF Research Database (Denmark)

    2008-01-01

    The present invention concerns the selective removal of nitrogen oxides (NOx) from gasses. In particular, the invention concerns a process, a catalyst and the use of a catalyst for the selective removal of nitrogen oxides in the presence of ammonia from gases containing a significant amount...... 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...

  11. Preparation of Co-Mo catalyst using activated carbon produced from egg shell and SiO2 as support – A hydrogenation study

    Directory of Open Access Journals (Sweden)

    Adeniyi Sunday Ogunlaja

    2010-12-01

    Full Text Available The preparation of a series of cobalt-molybdenum (Co-Mo catalysts supported on SiO2 and carbonized egg shells were investigated using standard procedures; the catalysts were further calcined at the 500 oC temperature to generate the internally consistent set, and the metal atoms content were varied in a regular manner. The ratio 1:4 (Co2+: Mo6+ by weight was employed for the various catalysts prepared. The carbonized egg shells were divided into two parts: the first part was leached with HNO3, as the other one was not leached. Activity tests were run using these catalysts containing leached and unleached carbon for the hydrogenation of methyl orange; the changes in absorbance regarding the unhydrogenated methyl orange at a wavelength of 460 nm were respectively 0.07 and 0.067 when the catalyst containing the leached carbonized egg shell (catalyst A and the catalyst containing the unleached activated carbon (catalyst B were used for the hydrogenation reaction. This confirms that catalyst A is more efficient in hydrogenating methyl orange than catalyst B.

  12. Liquid phase methanol LaPorte process development unit: Modification operation, and support studies. Task 3.6/3.7: Alternative catalyst/life run

    Energy Technology Data Exchange (ETDEWEB)

    1991-01-28

    In April 1987, Air Products started the third and final contract with the US Department of Energy to develop the Liquid Phase Methanol (LPMEOH) process. One of the objectives was to identify alternative commercial catalyst(s) for the process. This objective was strategically important as we want to demonstrate that the LPMEOH process is flexible and not catalyst selection limited. Among three commercially available catalysts evaluated in the lab, the catalyst with a designation of F21/0E75-43 was the most promising candidate. The initial judging criteria included not only the intrinsic catalyst activity but also the ability to be used effectively in a slurry reactor. The catalyst was then advanced for a 40-day life test in a laboratory 300 cc autoclave. The life test result also revealed superior stability when compared with that of a standard catalyst. Consequently, the new catalyst was recommended for demonstration in the Process Development Unit (PDU) at LaPorte, Texas. This report details the methodology of testing and selecting the catalyst.

  13. Computational Study of the Effect of Confinement within Microporous Structures on the Activity and Selectivity of Metallocene Catalysts for Ethylene Oligomerization

    KAUST Repository

    Toulhoat, Hervé

    2011-03-02

    The effect of confinement within some zeolitic structures on the activity and selectivity of metallocene catalysts for the ethylene oligomerization has been investigated using grand canonical Monte Carlo simulations (GCMC). The following zeolite (host) frameworks displaying different pore sizes, have been studied as solid hosts: mazzite (MAZ), AIPO-8 (AET), UTD-1F (DON), faujasite (FAU), and VPI-5 (VFI). Intermediates and transition states involved in the ethylene trimerization reaction catalyzed by a Ti-based catalyst [(η5-C5H4CMe2C6H 5)TiCl3/MAO] have been used as sorbates (guests). We have demonstrated linear correlations with slope aH,j between the adsorption enthalpy and the molecular volume Vm of the sorbates, each holding for a given microporous host below a host-specific threshold V mmax,j. Beyond this maximal molecular volume, the adsorption vanishes due to steric exclusion. aH,j increases, and Vmmax,j decreases with decreasing host pore size, in line with the confinement concept. We moreover showed that, in the limit of vanishing loading (Henry regime), the enthalpies and entropies of adsorption in a given host are linearly correlated. We have defined a host-specific confinement compensation temperature a j, which refers to a temperature where the stabilizing adsorption enthalpic interactions are canceled out against the loss in entropy. However, calculated aj are much larger than the operating temperatures. With a setup microkinetic model, we predict that the activity and selectivity of the confined Ti-catalyst in ethylene oligomerization can be significantly altered with respect to homogeneous phase conditions, since the adsorption free energies of transition states and intermediates also become functions of aH,j and Vm. We have applied this theory to predict the optimum host pore size to get maximum α-octene production, instead of α-hexene, which is primarily produced in the homogeneous phase. We also predict a significantly increased activity for

  14. The capacity of modified nickel catalysts derived from discharged catalyst of fertilizer plants for NOx treatment

    Science.gov (United States)

    Ha, T. M. P.; Luong, N. T.; Le, P. N.

    2016-11-01

    In Vietnam for recent years, a large amount of hazardous waste containing nickel (Ni) derived from discharged catalyst of fertilizer plants has caused environmental problems in landfill overloading and the risk of soil or surface water sources pollution. Taking advantage of discharged catalyst, recycling Ni components and then synthesizing new catalysts apply for mono-nitrogen oxides (NOx) treatments is an approach to bring about both economic and environmental benefits. This study was carried out with the main objective: Evaluate the performance of modified catalysts (using recovered Ni from the discharged RKS-2-7H catalyst of Phu My Fertilizer Plant) on NOx treatment. The catalysts was synthesized and modified with active phases consist of recovered Ni and commercial Barium oxide (BaO), Manganese dioxide (MnO2) / Cerium (IV) oxide (CeO2) on the support Aluminium oxide (γ-Al2O3). The results show that the modified catalysts with Ni, Ba, Ce was not more beneficial for NOx removal than which with Ni, Ba, Mn. 98% NOx removal at 350°C with the start temperature at 115°C and the T60 value at 307°C can be obtained with 10Ni10Ba10Mn/Al catalyst.

  15. Pathway and Surface Mechanism Studies of 1,3-butadiene Selective Oxidation Over Vanadium-Molybdenum-Oxygen Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, William David [Iowa State Univ., Ames, IA (United States)

    2001-01-01

    The partial oxidation of 1,3-butadiene has been investigated over VMoO catalysts synthesized by sol-gel techniques. Surface areas were 9-14 m2/g, and compositions were within the solid solution regime, i.e. below 15.0 mol % MoO3/(MoO3 + V2O5). Laser Raman Spectroscopy and XRD data indicated that solid solutions were formed, and pre- and post-reaction XPS data indicated that catalyst surfaces contained some V+4 and were further reduced in 1,3-butadiene oxidation. A reaction pathway for 1,3-butadiene partial oxidation to maleic anhydride was shown to involve intermediates such as 3,4-epoxy-1-butene, crotonaldehyde, furan, and 2-butene-1,4-dial. The addition of water to the reaction stream substantially increased catalyst activity and improved selectivity to crotonaldehyde and furan at specific reaction temperatures. At higher water addition concentrations, furan selectivity increased from 12% to over 25%. The catalytic effects of water addition were related to competitive adsorption with various V2O5-based surface sites, including the vanadyl V=O, corner sharing V-O-V and edge sharing V-O oxygen. Higher levels of water addition were proposed to impose acidic character by dissociative adsorption. In addition, a novel combinatorial synthesis technique for VMoO was used to investigate the phase transitions of V2O5, solid solutions of Mo in V2O5, V9Mo6O40, and other reduced VMoO compounds, characterized by laser Raman spectroscopy. The natural composition gradient imposed by the sputter deposition apparatus was used to create VMoO arrays containing 225 samples ranging from 7.0-42 mol% MoO3/(V2O5 + MoO3), determined by EDS analysis.

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

    Science.gov (United States)

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

    2017-04-03

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

  17. Pilot plant evaluation of hydrotreating catalysts for heavy gas oil conversion

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Y.; Chen, S.; Chen, J. [CanmetENERGY, Natural Resources Canada (Canada)

    2011-07-01

    As world reserves of oil are depleted, most of the oil remaining is heavy and sour and improvements in the technology are thus required to process it and produce transportation fuels. In terms of catalysts, alumina supported hydrotreating catalysts are commonly used; but activated carbon (AC) could also be a catalyst support option with its high microporosity and surface area combined with its thermal stability and resistance to coke deposition. This paper aims at determining the effect of the catalyst support on heavy crude oil processing. Experiments were conducted using two AC based catalysts, an alumina supported catalyst and two hydrotreating catalysts; results were then analyzed by scanning electron microscopy and transmission electron microscope. Results demonstrated that the AC based catalysts provide a better hydrotreating performance than the other catalysts. This study finds that the use of activated carbon based catalysts can provide better heavy oil conversion than others.

  18. 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.

  19. 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.

  20. 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...

  1. Heterogeneous chromium catalysts

    OpenAIRE

    2005-01-01

    The present invention relates to a heterogeneous chromium catalyst system for the polymerisation of ethylene and/or alpha olefins prepared by the steps of: (a) providing a silica-containing support, (b) treating the silica-containing support with a chromium compound to form a chromium-based silica-containing support, (c) activating the chromium-based silica-containing support, (d) chemically reducing the activated chromium-based silica-containing support to produce a precursor catalyst, (e) r...

  2. Adsorption/oxidation of CO on highly dispersed Pt catalyst studied by combined electrochemical and ATR-FTIRAS methods

    Energy Technology Data Exchange (ETDEWEB)

    Sato, T.; Kunimatsu, K. [Clean Energy Research Center, University of Yamanashi, 4 Takeda, Kofu 400-8510 (Japan); Uchida, H. [Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 4 Takeda, Kofu 400-8510 (Japan); Watanabe, M. [Clean Energy Research Center, University of Yamanashi, 4 Takeda, Kofu 400-8510 (Japan)], E-mail: m-watanabe@yamanashi.ac.jp

    2007-12-20

    Elecrochemical ATR-FTIRAS measurements were conducted for the first time to investigate nature of CO adsorbed under potential control on a highly dispersed Pt catalyst with average particle size of 2.6 nm supported on carbon black (Pt/C) and carbon un-supported Pt black catalyst (Pt-B). Each catalyst was uniformly dispersed by 10 {mu}g Pt/cm{sup 2} and fixed by Nafion film of 0.05 {mu}m thick on a gold film chemically deposited on a Si ATR prism window. Adsorption of CO was conducted at 0.05 V on the catalysts in 1 and 100% CO atmospheres, for which CO coverage, {theta}{sub CO}, was 0.69 and 1, respectively. Two well-defined {nu}(CO) bands free from band anomalies assigned to atop CO (CO(L)) and symmetrically bridge bonded CO (CO(B){sub sym.}) were observed. It was newly found that the CO(L) band was spitted into two well-defined peaks, particularly in 1% CO, from very early stage of adsorption, which was interpreted in terms of simultaneous occupation of terrace and step-edge sites, denoted as CO(L){sub terrace} and CO(L){sub edge}, respectively. This simultaneous occupation was commonly observed in our work both on Pt/C and Pt-B. A new band was also observed around 1950 cm{sup -1} in addition to the bands of CO(L) and CO(B){sub sym.}, which was assigned to asymmetric bridge CO, CO(B){sub asym.}, adsorbed on (1 0 0) terraces, based on our previous ECSTM observation of CO adsorption structures on (1 0 0) facet. The CO(B){sub asym.} on the Pt/C, particularly in 100% CO atmosphere, results in growth of a sharp band at 3650 cm{sup -1} accompanied by a concomitant development of a band around 3500 cm{sup -1}. The former and the latter are assigned to {nu}(OH) vibrations of non-hydrogen bonded and hydrogen bonded water molecules adsorbed on Pt, respectively, interpreted in term of results from a bond scission of the existing hydrogen bonded networks by CO(L)s and from a promotion of new hydrogen bonding among water molecules presumably by CO(B){sub asym.}. It was found

  3. (17)O MAS NMR studies of oxo-based olefin metathesis catalysts: a critical assessment of signal enhancement methods.

    Science.gov (United States)

    Grekov, D; Bouhoute, Y; Del Rosal, I; Maron, L; Taoufik, M; Gauvin, R M; Delevoye, L

    2016-10-12

    The DFS enhancement method as applied to (17)O MAS NMR was critically assessed, first on NaPO3, a simple binary glass system, and in a second step, on a series of catalysis-related organometallic molecules and materials. The robustness of DFS was investigated for the wide range of anisotropic parameters (quadrupolar coupling and chemical shift anisotropy) encountered in these samples. Emphasis has been put on the variation of signal enhancements with respect to the DFS final sweep frequency, pulse amplitude and pulse duration, while line shape distortion issues were also addressed. Finally, the robustness of DFS enhancement of the (17)O MAS NMR signal is shown through its successful application to silica-supported olefin metathesis catalysts.

  4. Self-regeneration mechanism of a perovskite-based catalyst studied with synchrotron radiation X-rays

    CERN Document Server

    Nishihata, Y

    2003-01-01

    A perovskite-based catalyst, LaFe sub 0 sub . sub 5 sub 7 Co sub 0 sub . sub 3 sub 8 Pd sub 0 sub . sub 0 sub 5 O sub 3 , maintains its high level of activity with high metal dispersion to control automotive emissions, such as nitrogen oxides (NO sub x), carbon monoxide (CO) and unburned hydrocarbons (HC). It has been demonstrated using X-ray anomalous diffraction (XAD) and X-ray absorption fine structure (XAFS) techniques that palladium reversibly moves between the inside and outside of the perovskite lattice, and that the agglomeration and growth of the metal particles is suppressed as a result of structural responses to the redox fluctuation in the exhaust-gas composition of current gasoline engines. (author)

  5. XPS and STEM study of the interface formation between ultra-thin Ru and Ir OER catalyst layers and perylene red support whiskers

    Directory of Open Access Journals (Sweden)

    Atanasoska Ljiljana L.

    2013-01-01

    Full Text Available The interface formation between nano-structured perylene red (PR whiskers and oxygen evolution reaction (OER catalysts ruthenium and iridium has been studied systematically by XPS and STEM. The OER catalyst over-layers with thicknesses ranging from ~0.1 to ~50 nm were vapor deposited onto PR ex-situ. STEM images demonstrate that, with increasing thickness, Ru and Ir transform from amorphous clusters to crystalline nanoparticles, which agglomerate with increased over-layer thickness. XPS data show a strong interaction between Ru and PR. Ir also interacts with PR although not to the extent seen for Ru. At low coverages, the entire Ru deposit is in the reacted state while a small portion of the deposited Ir remains metallic. Ru and Ir bonding occur at the PR carbonyl sites as evidenced by the attenuation of carbonyl photoemission and the emergence of new peak assigned to C-O single bond. The curve fitting analysis and the derived stoichiometry indicates the formation of metallo-organic bonds. The co-existence of oxide bonds is also apparent.

  6. A structure-activity study of Ni-catalyzed alkyl-alkyl Kumada coupling. Improved catalysts for coupling of secondary alkyl halides.

    Science.gov (United States)

    Ren, Peng; Vechorkin, Oleg; von Allmen, Kim; Scopelliti, Rosario; Hu, Xile

    2011-05-11

    A structure-activity study was carried out for Ni catalyzed alkyl-alkyl Kumada-type cross coupling reactions. A series of new nickel(II) complexes including those with tridentate pincer bis(amino)amide ligands ((R)N(2)N) and those with bidentate mixed amino-amide ligands ((R)NN) were synthesized and structurally characterized. The coordination geometries of these complexes range from square planar, tetrahedral, to square pyramidal. The complexes had been examined as precatalysts for cross coupling of nonactivated alkyl halides, particularly secondary alkyl iodides, with alkyl Grignard reagents. Comparison was made to the results obtained with the previously reported Ni pincer complex [((Me)N(2)N)NiCl]. A transmetalation site in the precatalysts is necessary for the catalysis. The coordination geometries and spin-states of the precatalysts have a small or no influence. The work led to the discovery of several well-defined Ni catalysts that are significantly more active and efficient than the pincer complex [((Me)N(2)N)NiCl] for the coupling of secondary alkyl halides. The best two catalysts are [((H)NN)Ni(PPh(3))Cl] and [((H)NN)Ni(2,4-lutidine)Cl]. The improved activity and efficiency was attributed to the fact that phosphine and lutidine ligands in these complexes can dissociate from the Ni center during catalysis. The activation of alkyl halides was shown to proceed via a radical mechanism. © 2011 American Chemical Society

  7. First-principles study on the Ni@Pt12 Ih core-shell nanoparticles: A good catalyst for oxygen reduction reaction

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zongxian, E-mail: yzx@henannu.edu.cn [College of Physics and Information Engineering, Henan Normal University, Xinxiang, Henan, 453007 (China); Henan Key Laboratory of Photovoltaic Materials, Xinxiang, 453007 (China); Zhang, Yanxing; Wang, Jinlong; Ma, Shuhong [College of Physics and Information Engineering, Henan Normal University, Xinxiang, Henan, 453007 (China)

    2011-08-15

    The adsorption, diffusion and dissociation properties of O{sub 2} on the icosahedron (Ih) Ni@Pt12 core-shell nanoparticle were investigated using the ab initio density functional theory calculations. It is found that, compared with the Pt(111) surface, the Ih Ni@Pt12 core-shell nanoparticle can enhance the adsorption, diffusion and dissociation of O{sub 2}, as well as the adsorption and diffusion of the atomic O (the dissociation product of O{sub 2}), and therefore serve as a good catalyst for oxygen reduction reaction. Our study gives a reasonable theoretical explanation to the high catalytic activity of the Ni@Pt core-shell nanoparticles for the oxygen reduction reaction. -- Highlights: → The Ni core can enhance the stability of the Ih Ni@Pt12 core-shell nanoparticle. → O{sub 2} prefers the top-bridge-top configuration on the Ih Ni@Pt12. → The Ih Ni@Pt12 can enhance the adsorption, diffusion and the dissociation of O{sub 2}. → The Ih Ni@Pt12 can serve as a good catalyst for the oxygen reduction reaction.

  8. Mechanism of Catalytic Water Oxidation by the Ruthenium Blue Dimer Catalyst: Comparative Study in D2O versus H2O

    Directory of Open Access Journals (Sweden)

    Yulia Pushkar

    2013-01-01

    Full Text Available Water oxidation is critically important for the development of energy solutions based on the concept of artificial photosynthesis. In order to gain deeper insight into the mechanism of water oxidation, the catalytic cycle for the first designed water oxidation catalyst, cis,cis-[(bpy2(H2ORuIIIORuIII(OH2(bpy2]4+ (bpy is 2,2-bipyridine known as the blue dimer (BD, is monitored in D2O by combined application of stopped flow UV-Vis, electron paramagnetic resonance (EPR and resonance Raman spectroscopy on freeze quenched samples. The results of these studies show that the rate of formation of BD[4,5] by Ce(IV oxidation of BD[3,4] (numbers in square bracket denote oxidation states of the ruthenium (Ru centers in 0.1 M HNO3, as well as further oxidation of BD[4,5] are slower in D2O by 2.1–2.5. Ce(IV oxidation of BD[4,5] and reaction with H2O result in formation of an intermediate, BD[3,4]′, which builds up in reaction mixtures on the minute time scale. Combined results under the conditions of these experiments at pH 1 indicate that oxidation of BD[3,4]′ is a rate limiting step in water oxidation with the BD catalyst.

  9. 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.

  10. Design of a high activity and selectivity alcohol catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Foley, H.C.; Mills, G.A.

    1992-11-30

    Efforts to synthesize bimetallic cluster-derived Rh-Mo catalysts for CO and CO[sub 2] hydrogenation to preferentially produce oxygenates. The rhodium-molybdenum cluster, (PPh[sub 3])[sub 2]RhMO(CO)([mu]-CO)[sub 2]Cp, was employed as a precursor to alumina- and silica-supported catalysts which were in CO hydrogenation. When compared to catalysts made from the distinct organometallic complexes, RhH(CO)(PPh[sub 3])[sub 3] and [MO(CO)[sub 3]Cp][sub 2], the catalysts derived from a binuclear precursor show higher activities for CO hydrogenation and superior selectivities towards oxygenates, namely, methanol, dimethyl ether and ethanol. Their product distributions depend on the support. Fourier transform infrared spectroscopy studies indicate that CO chemisorbs on cluster-derived catalysts as gem-dicarbonyls while it is chemisorbed only in the linear-carbonyl configuration on catalysts made from separate rhodium and molybdenum complexes. The particular oxygenate selectivity of the cluster-derived catalysts may be correlated to the strong electronic interaction between Rh and Mo. Carbon dioxide hydrogenation has also been carried out on the catalysts mentioned above. Again, the cluster-derived catalysts show higher oxygenate selectivities. Finally, the catalysts were studied with regard to both CO and CO[sub 2] hydrogenation kinetics, apparent activation energies inferred.

  11. Optimal Catalyst and Cocatalyst Precontacting in Industrial Ethylene Copolymerization Processes

    Directory of Open Access Journals (Sweden)

    Paul Aigner

    2016-01-01

    Full Text Available In industrial-scale catalytic olefin copolymerization processes, catalyst and cocatalyst precontacting before being introduced in the polymerization reactor is of profound significance in terms of catalyst kinetics and morphology control. The precontacting process takes place under either well-mixing (e.g., static mixers or plug-flow (e.g., pipes conditions. The scope of this work is to study the influence of mixing on catalyst/cocatalyst precontacting for a heterogeneous Ziegler-Natta catalyst system under different polymerization conditions. Slurry ethylene homopolymerization and ethylene copolymerization experiments with 1-butene are performed in a 0.5 L reactor. In addition, the effect of several key parameters (e.g., precontacting time, and ethylene/hydrogen concentration on catalyst activity is analyzed. Moreover, a comprehensive mass transfer model is employed to provide insight on the mass transfer process and support the experimental findings. The model is capable of assessing the external and internal mass transfer limitations during catalyst/cocatalyst precontacting process. It is shown that catalyst/cocatalyst precontacting is very important for the catalyst activation as well as for the overall catalyst kinetic behavior. The study reveals that there is an optimum precontacting time before and after which the catalyst activity decreases, while this optimum time depends on the precontacting mixing conditions.

  12. 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.

  13. 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.

  14. Synthesis, characterization, and activity of Co/Fe alumina/silica supported Ft catalysts and the study of promoter effect of ruthenium

    Science.gov (United States)

    Esumike, Sunday Azubike

    The alumina and hybrid alumina-silica FT catalyst were prepared by one-step solgel/oil-drop methods using metal-nitrate-solutions (method-I), and nanoparticle-metaloxides (method-2). The nanoparticle-metal-oxides did not participate in solubility equilibria in contrast to metal nitrate in method-1 causing no metal ion seepage; therefore, method-2 yields higher XRF metal loading efficiency than method-1. The thermal analysis confirmed that the metal loading by method-1 and method-2 involved two different pathways. Method-1 involves solubility equilibria in the conversion of metal-nitrate to metal- hydroxide and finally to metal-oxide, while in method-2 nanoparticle-metal-oxide remained intact during sol-gel-oil-drop and calcination steps. The alumina supported catalysts were dominated by gamma-alumina PXRD peaks in alumina catalysts while amorphous alumino-silicate phase was the bulk of hybrid alumina-silica catalysts. The presence of cobalt oxides (CoO, Co3O4) and iron oxides (FeO, Fe2O3) phases are confirmed in the catalysts prepared by method-1 and method-2. The PXRD analysis indicated weak peak intensities in catalysts with 5 wt. % total metal loading. PXRD pattern confirmed alloy formation in the bimetallic catalysts (CoFe2O4) on alumina support phase gamma-A12 O3. The surface area and pore diameter of hybrid alumina-silica granules (301 - 372 m2/g and 7.3 nm) showed better values than the alumina granules (251 - 256 m2/g and 6.5 nm). The support pore diameter of both types of granules is within the mesoporous range (1 - 50 nm). The morphology of all the catalysts is preserved upon metal loading and heat treatments. The surface characteristics of the sol-gel-oil-drop method prepared catalysts indicate there was no significant pore blockage of the support below 10 wt % total metal loading. The CO conversion of the FT catalysts was measured to screen catalytic active metals and determine the optimum temperatures of the FT reaction for the alumina catalysts. The

  15. TECHNOLOGY DEVELOPMENT FOR IRON FISCHER-TROPSCH CATALYSTS

    Energy Technology Data Exchange (ETDEWEB)

    Davis, B.H.

    1998-07-22

    The goal of the proposed work described in this Final Report was the development of iron-based Fischer-Tropsch catalysts that combined high activity, selectivity and life with physical robustness for slurry phase reactors that will produce either low-alpha or high-alpha products. The work described here has optimized the catalyst composition and pretreatment operation for a low-alpha catalyst. In parallel, work has been conducted to design a high-alpha iron catalyst that is suitable for slurry phase synthesis. Studies have been conducted to define the chemical phases present at various stages of the pretreatment and synthesis stages and to define the course of these changes. The oxidation/reduction cycles that are anticipated to occur in large, commercial reactors have been studied at the laboratory scale. Catalyst performance has been determined for catalysts synthesized in this program for activity, selectivity and aging characteristics.

  16. Availability of surface boron species in improved oxygen reduction activity of Pt catalysts: A first-principles study

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Libo; Zhou, Gang, E-mail: gzhou@mail.buct.edu.cn [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China)

    2016-04-14

    The oxidation process of boron (B) species on the Pt(111) surface and the beneficial effects of boron oxides on the oxygen reduction activity are investigated by first-principles calculations. The single-atom B anchored on the Pt surface has a great attraction for the oxygen species in the immediate environment. With the dissociation of molecular oxygen, a series of boron oxides is formed in succession, both indicating exothermic oxidation reactions. After BO{sub 2} is formed, the subsequent O atom immediately participates in the oxygen reduction reaction. The calculated O adsorption energy is appreciably decreased as compared to Pt catalysts, and more approximate to the optimal value of the volcano plot, from which is clear that O hydrogenation kinetics is improved. The modulation mechanism is mainly based on the electron-deficient nature of stable boron oxides, which normally reduces available electronic states of surface Pt atoms that bind the O by facilitating more electron transfer. This modification strategy from the exterior opens the new way, different from the alloying, to efficient electrocatalyst design for PEMFCs.

  17. Glycerol Steam Reforming Over Ni-Fe-Ce/Al2O3 Catalyst: Effect of Cerium.

    Science.gov (United States)

    Go, Gwang-Sub; Go, Yoo-Jin; Lee, Hong-Joo; Moon, Dong-Ju; Park, Nam-Cook; Kim, Young-Chul

    2016-02-01

    In this work, hydrogen production from glycerol by steam reforming was studied using Ni-metal oxide catalysts. Ni-based catalyst becomes deactivated during steam reforming reactions because of coke deposits and sintering. Therefore, the aim of this study was to reduce carbon deposits and sintering on the catalyst surface by adding a promoter. Ni-metal oxide catalysts supported on Al2O3 were prepared via impregnation method, and the calcined catalyst was reduced under H2 flow for 2 h prior to the reaction. The characteristics of the catalysts were examined by XRD, TPR, TGA, and SEM. The Ni-Fe-Ce/Al2O3 catalyst, which contained less than 2 wt% Ce, showed the highest hydrogen selectivity and glycerol conversion. Further analysis of the catalysts revealed that the Ni-Fe-Ce/Al2O3 catalyst required a lower reduction temperature and produced minimum carbon deposit.

  18. Study of the kinetics of palladium catalysts with 2-metoxy-naphtyl-diferrocenyl-, 2-tert-butyl-oxiphenyl-diferrocenyl-phosphine and 1,1’-diphenyl-phosphin-ferrocene ligands

    Directory of Open Access Journals (Sweden)

    Alibek Khabiyev

    2014-08-01

    Full Text Available The article presents results of the study on kinetic of palladium catalyst with 2-metoxy-naphtyl-diferrocenyl-, 2-tret-butyl-oxiphenyl-diferrocenyl-phosphin and 1,1’-diphenyl-phosphin-ferrocen ligands in Suzuki-Miyara test-reactions. The advantage of Suzuki reactions in difference from other cross-coupling reactions is the use of insensitive to water and oxygen thermostable organoboron compounds. As boronic acid was used phenylboronic acid and as weak base – potassium phosphate. All used catalysts showed good activity with arylbromides and weak activity with arylchlorides.

  19. In situ Transmission Electron Microscopy of catalyst sintering

    DEFF Research Database (Denmark)

    DeLaRiva, Andrew T.; Hansen, Thomas Willum; Challa, Sivakumar R.

    2013-01-01

    along with our recent in situ TEM studies on the sintering of Ni/MgAl2O4 catalysts. These results suggest that the rapid loss of catalyst activity in the earliest stages of catalyst sintering could result from Ostwald ripening rather than through particle migration and coalescence. The smallest...... of Ostwald ripening as well as atomistic Monte Carlo simulations are both in good agreement with these experimental observations, predicting a steep loss in catalyst activity at short times on stream. The in situ studies show the importance of direct observations to deduce mechanisms and show the important...

  20. Dynamic study of carbon nanotube growth and catalyst morphology evolution during acetylene decomposition on Co/SBA-15 in an environmental TEM

    DEFF Research Database (Denmark)

    s Aires, F. J. Cadete Santo; Epicier, T.; Wagner, Jakob Birkedal

    2012-01-01

    post mortem TEM measurements and real-time in situ ETEM observations. In situ observation of the formation of the carbon nanotubes was performed in an FEI Titan 80-300 ETEM equipped with an objective lens spherical aberration corrector [3]. Prior to acetylene decomposition, the catalyst nanoparticles...... were reduced in situ in a flow of hydrogen (1 mbar, ~500°C). Electron energy-loss spectra taken before and during reduction showed that the Co oxide nanoparticles were reduced to metallic Co. In situ high resolution TEM images are consistent with cubic Co. A first attempt to study carbon nanotube......-3/10-2 mbar range was used to decrease the growth rate to allow real-time observation of the formation of CNTs over several minutes. These conditions also reduced the coking of the nanoparticles and favoured the formation of tubular structures. Two types of CNTs following the tip-growth mechanism...

  1. CCDC 1521591: Experimental Crystal Structure Determination : dotriacontakis(mu-2,4-dimethylbenzenethiolato)-octakis(triphenylphosphine)-heptahexaconta-silver tris(tetraphenylborate) unknown solvate

    KAUST Repository

    Alhilaly, Mohammad J.

    2016-01-01

    An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

  2. Alcohol selective oxidation over modified foam-silver catalysts

    OpenAIRE

    Pestryakov, Alexeij N.; Bogdanchikova, Nina. E.; Knop-Gericke, Axel

    2004-01-01

    Catalysts based on silver supported on foam ceramics and modified by Zr, Ce and La oxides have been studied in the process of partial oxidation of methanol to formaldehyde. The foam catalysts exhibit high catalytic, mechanical and gas-dynamic properties exceeding the characteristics of conventional crystalline and supported silver samples. Modifying additives of Zr and Ce oxides raise activity and selectivity of the supported foam-silver catalyst as well as its stability during the prolonged ...

  3. Optimal Catalyst and Cocatalyst Precontacting in Industrial Ethylene Copolymerization Processes

    OpenAIRE

    Paul Aigner; Christian Paulik; Apostolos Krallis; Vasileios Kanellopoulos

    2016-01-01

    In industrial-scale catalytic olefin copolymerization processes, catalyst and cocatalyst precontacting before being introduced in the polymerization reactor is of profound significance in terms of catalyst kinetics and morphology control. The precontacting process takes place under either well-mixing (e.g., static mixers) or plug-flow (e.g., pipes) conditions. The scope of this work is to study the influence of mixing on catalyst/cocatalyst precontacting for a heterogeneous Ziegler-Natta cata...

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

    Directory of Open Access Journals (Sweden)

    Widodo Purwanto

    2010-10-01

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

  5. Fischer-Tropsch Synthesis over Iron Manganese Catalysts: Effect of Preparation and Operating Conditions on Catalyst Performance

    Directory of Open Access Journals (Sweden)

    Ali A. Mirzaei

    2009-01-01

    molar basis which is the most active catalyst for the conversion of synthesis gas to light olefins. The effects of different promoters and supports with loading of optimum support on the catalytic performance of catalysts are also studied. It was found that the catalyst containing 50%Fe/50%Mn/5 wt.%Al2O3 is an optimum-modified catalyst. The catalytic performance of optimal catalyst has been studied in operation conditions such as a range of reaction temperatures, H2/CO molar feed ratios and a range of total pressures. Characterization of both precursors and calcined catalysts is carried out by powder X-ray diffraction (XRD, scanning electron microscopy (SEM, BET specific surface area and thermal analysis methods such as TGA and DSC.

  6. 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...... be used as solid acid catalysts but can also be used as a size-selective matrix. It was shown that it is possible to encapsulate 1-2 nm sized gold nanoparticles by silicalite-1 or ZSM-5 zeolite crystals thereby forming a sintering-stable and substrate size-selective oxidation catalyst. After carrying out...

  7. 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.

  8. Recycling of polymer waste with fluid catalytic cracking catalysts.

    Science.gov (United States)

    Ali, Salmiaton; Garforth, Arthur; Fakhru'l-Razi, A

    2006-01-01

    Feedstock recycling of high-density polyethylene (HDPE) over fluid catalytic cracking (FCC) catalysts (1:6 ratio) was carried out using a laboratory fluidized bed reactor operating at 450 degrees C. Fresh and steam deactivated commercial FCC catalysts with different levels of rare earth oxide (REO) were compared as well as used FCC catalysts (E-Cats) with different levels of metal poisoning. Fresh FCC catalysts gave the highest results of HDPE degradation in terms of yield of volatile hydrocarbon product. Meanwhile, steamed FCC catalysts and used FCC catalysts showed similar but lower yields. Overall, the product yields from HDPE cracking showed that the level of metal contamination (nickel and vanadium) did not affect the product stream generated from polymer cracking. This study gives promising results as an alternative technique for the cracking and recycling of polymer waste.

  9. Thin Film Catalyst Layers for Direct Methanol Fuel Cells

    Science.gov (United States)

    Witham, C. K.; Chun, W.; Ruiz, R.; Valdez, T. I.; Narayanan, S. R.

    2000-01-01

    One of the primary obstacles to the widespread use of the direct methanol fuel cell (DMFC) is the high cost of the catalyst. Therefore, reducing the catalyst loading well below the current level of 8-12 mg/cm 2 would be important to commercialization. The current methods for preparation of catalyst layers consisting of catalyst, ionomer and sometimes a hydrophobic additive are applied by either painting, spraying, decal transfer or screen printing processes. Sputter deposition is a coating technique widely used in manufacturing and therefore particularly attractive. In this study we have begun to explore sputtering as a method for catalyst deposition. Present experiments focus on Pt-Ru catalyst layers for the anode.

  10. Hydrogenation of artemisinin to dihydroartemisinin over heterogeneous metal catalysts

    Science.gov (United States)

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

    2017-01-01

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

  11. 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.

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

    OpenAIRE

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

    2005-01-01

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

  13. Core-shell nanostructured catalysts.

    Science.gov (United States)

    Zhang, Qiao; Lee, Ilkeun; Joo, Ji Bong; Zaera, Francisco; Yin, Yadong

    2013-08-20

    excellent catalytic activity for the oxidation of organic compounds under UV, visible, and direct sunlight. The enhanced photocatalytic efficiency of this nanostructure resulted from an added interfacial nonmetal doping, which improved visible light absorption, and from plasmonic metal decoration that enhanced light harvesting and charge separation. In addition to our synthetic efforts, we have developed ways to evaluate the accessibility of reactants to the metal cores and to characterize the catalytic properties of the core-shell samples we have synthesized. We have adapted infrared absorption spectroscopy and titration experiments using carbon monoxide and other molecules as probes to study adsorption on the surface of metal cores in metal oxide-shell structures in situ in both gas and liquid phases. In particular, the experiments in solution have provided insights into the ease of diffusion of molecules of different sizes in and out of the shells in these catalysts.

  14. Hydroconversion of Waste Cooking Oil into Green Biofuel over Hierarchical USY-Supported NiMo Catalyst: A Comparative Study of Desilication and Dealumination

    Directory of Open Access Journals (Sweden)

    Zongwei Zhang

    2017-09-01

    Full Text Available The hydroconversion of waste cooking oil into hydrocarbon fuel was investigated over the hierarchical USY zeolite-supported NiMo catalysts which were prepared by dealumination ((NH42SiF6/desilication (NaOH. The physical and acidity properties of the hierarchical catalysts were characterized by X-ray diffraction (XRD, the Brunauer-Emmett-Teller (BET infrared spectroscopy of adsorbed pyridine (Py-IR, ammonia temperature-programmed desorption (NH3-TPD, and H2 temperature-programmed reduction (H2-TPR. The Brønsted/Lewis (B/L acid distribution was little affected by dealumination and the acid density decreased significantly. However, the highly-desilicated catalysts decreased the B/L ratio obviously. Therefore, many more Mo species in the NiMoO4− and MoO3 phases were produced in the AHFS-treated catalysts, while more high-valence-state Mo species in the NiMoO4− phase were formed in the NaOH-treated catalysts. The AHFS-treated catalysts showed higher catalytic activity and better DCO2 selectivity and selective cracking for jet fuel. The 42.3% selectivity of jet fuel and 13.5% selectivity of jet-range aromatics was achieved over the 8 wt % (NH42SiF6-treated catalyst with 67% DCO2 selectivity.

  15. A kinetic and spectroscopic study on the copper catalyzed oxidative coupling polymerization of 2,6-dimethylphenol. X-ray structure of the catalyst precursor tetrakis(N-methylimidazole)bis(nitrato)copper(II)

    NARCIS (Netherlands)

    Baesjou, PJ; Driessen, WL; Challa, G; Reedijk, J

    1996-01-01

    The complex of copper(II) nitrate with N-methylimidazole (Nmiz) ligand has been studied as a catalyst for the oxidative coupling of 2,6-dimethylphenol by means of kinetic and spectroscopic measurements. The order of the reaction in copper is fractional and depends on the N/Cu ratio and the base/Cu

  16. Effect of the nickel precursor on the impregnation and drying of γ-Al2O3 catalyst bodies: a UV-vis and IR micro-spectroscopic study

    NARCIS (Netherlands)

    Espinosa Alonso, L.; de Jong, K.P.; Weckhuysen, B.M.

    2008-01-01

    The elemental preparation steps of impregnation and drying of Ni/g-Al2O3 catalyst bodies have been studied by combining UV-vis and IR microspectroscopy. The influence of the number of chelating ligands in [Ni(en)x(H2O)6-2x]2+ precursor complexes (with en ) ethylenediamine and x ) 0-3) has been

  17. Preparation and Characterization of Anadara Granosa Shells and CaCO3 as Heterogeneous Catalyst for Biodiesel Production

    National Research Council Canada - National Science Library

    Hadiyanto Hadiyanto; Sri Puji Lestari; Widayat Widayat

    2016-01-01

    .... The CaCO3 based catalyst gained high yield of biodiesel (94%) as compared to Anadara granoasa based catalyst (92%). The reusability study showed that these catalysts could be used until three times recycle with 40-60% yield of biodiesel. The CaO contents of catalyst decreased up to 90% after three times recycles.

  18. 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....

  19. Preparation of Co-Mo catalyst using activated carbon produced from egg shell and SiO2 as support – A hydrogenation study

    OpenAIRE

    Adeniyi Sunday Ogunlaja; Alade, Olalekan S.; Funmilola Y. Oladipo

    2010-01-01

    The preparation of a series of cobalt-molybdenum (Co-Mo) catalysts supported on SiO2 and carbonized egg shells were investigated using standard procedures; the catalysts were further calcined at the 500 oC temperature to generate the internally consistent set, and the metal atoms content were varied in a regular manner. The ratio 1:4 (Co2+: Mo6+) by weight was employed for the various catalysts prepared. The carbonized egg shells were divided into two parts: the first part was leached with HN...

  20. Salesperson, Catalyst, Manager, Leader.

    Science.gov (United States)

    Worth, Michael J.; Asp, James W., II

    1996-01-01

    This article examines four roles of the college or university development officer: salesperson (when direct solicitation is seen as the officer's primary role); catalyst (or sales manager, adviser, expert, facilitator); manager (stressing the importance of the overall office functioning); and leader (who exerts a leadership role in the…

  1. Heterogeneous chromium catalysts

    NARCIS (Netherlands)

    2005-01-01

    The present invention relates to a heterogeneous chromium catalyst system for the polymerisation of ethylene and/or alpha olefins prepared by the steps of: (a) providing a silica-containing support, (b) treating the silica-containing support with a chromium compound to form a chromium-based

  2. 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.

  3. 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.

  4. 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.

  5. Synthesis of the catalyst

    Indian Academy of Sciences (India)

    Admin

    50 585; Duan Y C, Ma Y C, Zhang E, Shi X J, Wang M M, Ye X W and Liu H M 2013 Design and synthesis of novel 1,2,3-triazole-dithiocarbamate hybrids as ... M, Minato T, Bao M and Yamamoto Y 2011 Nanoporous Copper Metal Catalyst in Click Chemistry: Nanoporosity-Dependent Activity without Supports and Bases; ...

  6. Catalysts for Environmental Remediation

    DEFF Research Database (Denmark)

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

    2013-01-01

    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...

  7. Glucose reactions with acid and base catalysts in hot compressed water at 473 K.

    Science.gov (United States)

    Watanabe, Masaru; Aizawa, Yuichi; Iida, Toru; Aida, Taku M; Levy, Caroline; Sue, Kiwamu; Inomata, Hiroshi

    2005-09-05

    The effects of the homogeneous catalysts (H(2)SO(4) and NaOH) and heterogeneous catalysts (TiO(2) and ZrO(2)) on glucose reactions were examined in hot compressed water (473 K) by a batch-type reactor. From the homogeneous catalyst studies, we confirmed that the acid catalyst promoted dehydration, while isomerization of glucose to fructose was catalyzed by alkali. Anatase TiO(2) was found to act as an acid catalyst to promote formation of 5-hydroxymethylfuraldehyde (HMF). Zirconia (ZrO(2)) was a base catalyst to promote the isomerization of glucose. The effects of the additives were also confirmed through fructose reactions.

  8. APPLICATION IN BUILDING A NEW TYPE CATALYST WITH FRACTALS V. ECO CATALYST

    Directory of Open Access Journals (Sweden)

    RADU Ionuţ Valentin

    2012-09-01

    Full Text Available This paper presents a study on the existence of fractal and pollution prevention methods. One way to reduce emissions of greenhouse gases from motor vehicles is to systematically collect and dispose of any waste (high emissions. This paper treats a new type of catalyst, the catalytic oxidation process improvement. This new type of catalyst can be produced at sizes much smaller than those on the market because the surface of monolithic spiral have introduced a series of fractals.

  9. Biomimetic Water-Oxidation Catalysts: Manganese Oxides.

    Science.gov (United States)

    Kurz, Philipp

    2016-01-01

    The catalytic oxidation of water to molecular oxygen is a key process for the production of solar fuels. Inspired by the biological manganese-based active site for this reaction in the enzyme Photosystem II, researchers have made impressive progress in the last decades regarding the development of synthetic manganese catalysts for water oxidation. For this, it has been especially fruitful to explore the many different types of known manganese oxides MnOx. This chapter first offers an overview of the structural, thermodynamic, and mechanistic aspects of water-oxidation catalysis by MnOx. The different test systems used for catalytic studies are then presented together with general reactivity trends. As a result, it has been possible to identify layered, mixed Mn (III/IV)-oxides as an especially promising class of bio-inspired catalysts and an attempt is made to give structure-based reasons for the good performances of these materials. In the outlook, the challenges of catalyst screenings (and hence the identification of a "best MnOx catalyst") are discussed. There is a great variety of reaction conditions which might be relevant for the application of manganese oxide catalysts in technological solar fuel-producing devices, and thus catalyst improvements are currently still addressing a very large parameter space. Nonetheless, detailed knowledge about the biological catalyst and a solid experimental basis concerning the syntheses and water-oxidation reactivities of MnOx materials have been established in the last decade and thus this research field is well positioned to make important contributions to solar fuel research in the future.

  10. Fundamental studies of the mechanism of catalytic reactions with catalysts effective in the gasification of carbon solids and the oxidative coupling of methane. Quarterly report, October 1, 1994--December 31, 1994

    Energy Technology Data Exchange (ETDEWEB)

    Iglesia, E.; Perry, D.L.; Heinemann, H.

    1994-12-01

    This report describes research on the oxidative coupling of methane and catalysts involved in coal gasification. Topics include methane pyrolysis and catalysts, and magnetic properties of the coal gasification catalyst Ca-Ni-K-O system.

  11. SYNTHESIS OF BIODIESEL ON A HYBRID CATALYTIC-PLASMA REACTOR OVER K2O/CaO-ZnO CATALYST

    OpenAIRE

    Luqman Buchori; Istadi Istadi; Purwanto Purwanto

    2017-01-01

    This paper aimed to study the synergistic effects of dielectric barrier discharge plasma and 5 % K2O/CaO-ZnO catalyst on biodiesel synthesis. The catalyst was prepared using co-precipitation followed by impregnation method. The catalyst was characterized by XRD, while the catalyst basicity was tested by titration method. The effects of voltage, weight hourly space velocity (WHSV), and catalyst pellet diameter on the yield of fatty acid methyl ester (FAME) and biodiesel were studied. The trans...

  12. 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.

  13. 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

  14. A comparative study of solid carbon acid catalysts for the esterification of free fatty acids for biodiesel production. Evidence for the leaching of colloidal carbon.

    Science.gov (United States)

    Deshmane, Chinmay A; Wright, Marcus W; Lachgar, Abdessadek; Rohlfing, Matthew; Liu, Zhening; Le, James; Hanson, Brian E

    2013-11-01

    The preparation of a variety of sulfonated carbons and their use in the esterification of oleic acid is reported. All sulfonated materials show some loss in activity associated with the leaching of active sites. Exhaustive leaching shows that a finite amount of activity is lost from the carbons in the form of colloids. Fully leached catalysts show no loss in activity upon recycling. The best catalysts; 1, 3, and 6; show initial TOFs of 0.07 s(-1), 0.05 s(-1), and 0.14 s(-1), respectively. These compare favorably with literature values. Significantly, the leachate solutions obtained from catalysts 1, 3, and 6, also show excellent esterification activity. The results of TEM and catalyst poisoning experiments on the leachate solutions associate the catalytic activity of these solutions with carbon colloids. This mechanism for leaching active sites from sulfonated carbons is previously unrecognized. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Study of Catalysts and Electrocatalysts for NO{sub x} Removal in Combustion Gases ELECTRONOX Project Final Report; Estudio de Catalizadores y Electrocatalizadores para la Eliminacion de NO{sub x} en Gases de Combustion. Informe Final Proyecto ELECTRONOX

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz Martinez, E.; Marono Bujan, M.; Sanchez-Hervas, J. M.

    2009-12-11

    The final aim of the ELECTRONOX project was to develop new methodologies and technologies for NO{sub x} removal. To fulfil this objective, studies of selective catalytic reduction of NO{sub x} with hydrocarbons, both conventional and with electrochemical promotion, have been undertaken at pilot plant level, using appropriate catalyst/electrocatalysts configurations and in conditions similar to those required in their possible practical application. None of the catalysts/electrocatalysts studied is active and stable enough, under realistic conditions, to consider its possible industrial application, because the value of NO{sub x} conversion achieved by selective catalytic reduction with hydrocarbons, both conventional and with electrochemical promotion, decreases in presence of the different inhibitors and poisons present in the combustion gas, while the promotional effect on the catalytic activity and selectivity is more pronounced. In addition, the catalysts/electrocatalysts suffer from different deactivation processes, such as: sulphur poisoning, carbon deposition and sintering. However, the developed electrochemical catalyst looks promising for NO{sub x} removal in combustion gases, because it can be promoted under realistic operating conditions. (Author) 23 refs.

  16. Hydration effects on the molecular structure of silica-supported vanadium oxide catalysts: A combined IR, Raman, UV–vis and EXAFS study

    OpenAIRE

    Keller, D.E.; Visser, T; Soulimani, F.; Koningsberger, D. C.; Weckhuysen, B.M.

    2007-01-01

    The effect of hydration on the molecular structure of silica-supported vanadium oxide catalysts with loadings of 1–16 wt.% V has been systematically investigated by infrared, Raman, UV–vis and EXAFS spectroscopy. IR and Raman spectra recorded during hydration revealed the formation of V–OH groups, characterized by a band at 3660 cm−1. Hydroxylation was found to start instantaneously upon exposure to traces of water, reflecting a very high sensitivity of the supported vanadium oxide catalysts ...

  17. Mechanistic studies of olefin and alkyne trimerization with chromium catalysts: deuterium labeling and studies of regiochemistry using a model chromacyclopentane complex.

    Science.gov (United States)

    Agapie, Theodor; Labinger, Jay A; Bercaw, John E

    2007-11-21

    A system for catalytic trimerization of ethylene utilizing chromium(III) precursors supported by diphosphine ligand PNP(O4) = (o-MeO-C6H4)2PN(Me)P(o-MeO-C6H4)2 has been investigated. The mechanism of the olefin trimerization reaction was examined using deuterium labeling and studies of reactions with alpha-olefins and internal olefins. A well-defined chromium precursor utilized in this studies is Cr(PNP(O4))(o,o'-biphenyldiyl)Br. A cationic species, obtained by halide abstraction with NaB[C6H3(CF3)2]4, is required for catalytic turnover to generate 1-hexene from ethylene. The initiation byproduct is vinylbiphenyl; this is formed even without activation by halide abstraction. Trimerization of 2-butyne is accomplished by the same cationic system but not by the neutral species. Catalytic trimerization, with various (PNP(O4))Cr precursors, of a 1:1 mixture of C2D4 and C2H4 gives isotopologs of 1-hexene without H/D scrambling (C6D12, C6D8H4, C6D4H8, and C6H12 in a 1:3:3:1 ratio). The lack of crossover supports a mechanism involving metallacyclic intermediates. Using a SHOP catalyst to perform the oligomerization of a 1:1 mixture of C2D4 and C2H4 leads to the generation of a broader distribution of 1-hexene isotopologs, consistent with a Cossee-type mechanism for 1-hexene formation. The ethylene trimerization reaction was further studied by the reaction of trans-, cis-, and gem-ethylene-d2 upon activation of Cr(PNP(O4))(o,o'-biphenyldiyl)Br with NaB[C6H3(CF3)2]4. The trimerization of cis- and trans-ethylene-d2 generates 1-hexene isotopomers having terminal CDH groups, with an isotope effect of 3.1(1) and 4.1(1), respectively. These results are consistent with reductive elimination of 1-hexene from a putative Cr(H)[(CH2)4CH=CH2] occurring much faster than a hydride 2,1-insertion or with concerted 1-hexene formation from a chromacycloheptane via a 3,7-H shift. The trimerization of gem-ethylene-d2 has an isotope effect of 1.3(1), consistent with irreversible formation of a

  18. A comparative study of alumina-supported Ni catalysts prepared by photodeposition and impregnation methods on the catalytic ozonation of 2,4-dichlorophenoxyacetic acid

    Energy Technology Data Exchange (ETDEWEB)

    Rodríguez, Julia L., E-mail: ozliliana@yahoo.com.mx [Lab. Ing. Química Ambiental. ESIQIE–Instituto Politécnico Nacional (Mexico); Valenzuela, Miguel A. [Lab.Catálisis y Materiales. ESIQIE–Instituto Politécnico Nacional. Zacatenco (Mexico); Tiznado, Hugo [Centro de Nanociencias y Nanotecnología. CNyN Universidad Nacional Autónoma de México (Mexico); Poznyak, Tatiana [Lab. Ing. Química Ambiental. ESIQIE–Instituto Politécnico Nacional (Mexico); Chairez, Isaac [Departamento de Bioprocesos, UPIBI- Instituto Politécnico Nacional (Mexico); Magallanes, Diana [Lab. Ing. Química Ambiental. ESIQIE–Instituto Politécnico Nacional (Mexico)

    2017-02-15

    The heterogeneous catalytic ozonation on unsupported and supported oxides has been successfully tested for the removal of several refractory compounds in aqueous solution. In this work, alumina-supported nickel catalysts prepared by photodeposition and impregnation methods were compared in the catalytic ozonation of 2,4-dichlorophenoxyacetic acid (2,4-D). The catalysts were characterized by high-resolution electron microscopy and X-ray photoelectron spectroscopy. The photochemical decomposition of Ni acetylacetonate to produce Ni(OH){sub 2}, NiO, and traces of Ni° deposited on alumina was achieved in the presence of benzophenone as a sensitizer. A similar surface composition was found with the impregnated catalyst after its reduction with hydrogen at 500 °C and exposed to ambient air. Results indicated a higher initial activity and maleic acid (byproduct) concentration with the photodeposited catalyst (1 wt% Ni) compared to the impregnated catalyst (3 wt% Ni). These findings suggest the use of the photodeposition method as a simple and reliable procedure for the preparation of supported metal oxide/metal catalysts under mild operating conditions.

  19. Pt/C Fuel Cell Catalyst Degradation

    DEFF Research Database (Denmark)

    Zana, Alessandro

    This thesis investigates the degradation behavior of Pt/C catalysts under simulated automotive conditions. By using the “tool box” synthesis method the Pt loading has been changed from low to high Pt loadings, therefore permitting to study the role of Pt on the degradation of high surface area (HSA......) Pt/C catalyst. Diverse degradation mechanisms have been found to be responsible for the electrochemical surface area loss (ECSA). The different degradation mechanisms have been found to be dependent from the diverse potential windows applied during the stress test. Furthermore the synthesis approach......, i.e. Vulcan XC72R and Ketjenblack EC-300J. The ECSA loss measured for Vulcan XC72R was significantly higher after start/stop than for Ketjenblack EC-300J. To this concern the Pt loaded Vulcan XC72R and Ketjenblack EC- 300J has been studied by Raman spectroscopy. The Raman spectra of the catalysts...

  20. Optimization of Reactor Temperature and Catalyst Weight for Plastic Cracking to Fuels Using Response Surface Methodology

    OpenAIRE

    Istadi Istadi; S Suherman; Luqman Buchori

    2011-01-01

    The present study deals with effect of reactor temperature and catalyst weight on performance of plastic waste cracking to fuels over modified catalyst waste as well as their optimization. From optimization study, the most operating parameters affected the performance of the catalytic cracking process is reactor temperature followed by catalyst weight. Increasing the reactor temperature improves significantly the cracking performance due to the increasing catalyst activity. The optimal operat...

  1. 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...

  2. Discovery of technical methanation catalysts based on computational screening

    DEFF Research Database (Denmark)

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

    2007-01-01

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

  3. Chemical nature of catalysts of oxide nanoparticles in environment ...

    Indian Academy of Sciences (India)

    Carbon nanostructures (CNS) are often grown using oxide nanoparticles as catalyst in chemical vapour deposition and these oxides are not expected to survive as such during growth. In the present study, the catalysts of cobalt- and nickel oxide-based nanoparticles of sizes varying over a range have been reduced at 575 ...

  4. Hysteresis Phenomena in Sulfur Dioxide Oxidation over Supported Vanadium Catalysts

    DEFF Research Database (Denmark)

    Masters, Stephen G.; Eriksen, Kim Michael; Fehrmann, Rasmus

    1997-01-01

    Catalyst deactivation and hysteresis behavior in industrial SO2-oxidation catalysts have been studied in the temperature region 350-480 C by combined in situ EPR spectroscopy and catalytic activity measurements. The feed gas composition simulated sulfuric acid synthesis gas and wet/dry de...

  5. A Catalyst-for-Change Approach to Evaluation Capacity Building

    Science.gov (United States)

    Garcia-Iriarte, Edurne; Suarez-Balcazar, Yolanda; Taylor-Ritzler, Tina; Luna, Maria

    2011-01-01

    Evaluation capacity building (ECB) has become a popular approach for helping community-based organizations (CBOs) to meet their funders' demands for accountability. This case study reports the ECB process with one staff member using a catalyst-for-change approach. The authors analyzed the role of the catalyst in diffusing evaluation knowledge and…

  6. Catalysts for biobased fuels. New catalyst formulations for vehicles fuelled by biobased motor fuels

    Energy Technology Data Exchange (ETDEWEB)

    Pettersson, L.J.; Wahlberg, A.M.; Jaeraas, S.G. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Chemical Technology

    1997-12-01

    The long-term objective for the project is to develop tailor-made exhaust gas catalysts for heavy-duty vehicles fuelled by biobased motor fuels operating in urban traffic. In this report an experimental study of catalytic oxidation of ethanol in a laboratory flow reactor is presented. The miniature catalyst samples consisted of monolithic cordierite substrates onto which various combinations of washcoat material and active material were applied. Oxides of Cu and Cu-Mn, as well as different combinations of precious metals were evaluated as active material supported on various washcoat materials. The experimental conditions were chosen in order to simulate the exhaust from a diesel engine fuelled by neat ethanol. Catalyst characterization included measurements of BET surface area and pore size distribution as well as temperature programmed reduction (TPR) analysis. When comparing the TPR profiles with the light-off curves from the ethanol oxidation experiments, we have found an indication of a correlation between activity and reducibility of the catalyst. There also seems to be a correlation between TPR profile and pore size distribution for titania-supported catalysts. When combining two precious metals as active material, a positive synergistic effect has been observed. The light-off temperature (T{sub 50}) is considerably lower for some of these combinations than for the corresponding monometallic catalysts. The base metal oxide catalysts tested were more selective for oxidation of ethanol to carbon dioxide and water than the precious metal catalysts. The results also indicate that the oxidation of nitric oxide to the more hazardous nitrogen dioxide can be suppressed by using a suitable combination of active material and washcoat material 45 refs, 97 figs, 4 tabs

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2002-03-08

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

  8. Deactivation and Regeneration of Ni/ZA Catalyst in Hydrocracking of Polypropylene

    Directory of Open Access Journals (Sweden)

    Imam Khabib

    2014-07-01

    Full Text Available The phenomena of catalyst deactivation and the effects of regeneration method on the characteristics and activity of Ni/ZA catalyst after being used in a continuous cracking reaction of polypropylene have been studied. Ni/ZA catalyst was prepared using sonochemical method with total metal intake of 4%. Characteristics and activity of fresh, spent, and regenerated catalyst were evaluated to get a better understanding about the catalyst deactivation. Characteristics which have been observed include catalyst acidity, porosity, crystallinity, and surface morphology. Catalytic activity test of Ni/ZA catalyst on polypropylene cracking reaction at temperature of 500 °C with H2 flow rate of 20 mL/min and catalyst:feed ratio of 1:2 (w/w showed the decrease of some catalyst characteristics such as specific surface area, total pore volume, and acidity due to coke fouling over a five-times continuous experiment. Regeneration of catalyst with oxidation-reduction method has been able to increase the activity and acidity of catalyst up to 7.47% and 38.54%, respectively, compared to those of spent catalyst, while the catalyst surface area and total pore volume decreased up to 32.83% and 26.92%, respectively.

  9. Heterogeneous Catalyst Deactivation and Regeneration: A Review

    Directory of Open Access Journals (Sweden)

    Morris D. Argyle

    2015-02-01

    Full Text Available Deactivation of heterogeneous catalysts is a ubiquitous problem that causes loss of catalytic rate with time. This review on deactivation and regeneration of heterogeneous catalysts classifies deactivation by type (chemical, thermal, and mechanical and by mechanism (poisoning, fouling, thermal degradation, vapor formation, vapor-solid and solid-solid reactions, and attrition/crushing. The key features and considerations for each of these deactivation types is reviewed in detail with reference to the latest literature reports in these areas. Two case studies on the deactivation mechanisms of catalysts used for cobalt Fischer-Tropsch and selective catalytic reduction are considered to provide additional depth in the topics of sintering, coking, poisoning, and fouling. Regeneration considerations and options are also briefly discussed for each deactivation mechanism.

  10. 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.

  11. Exploring Catalyst Behaviours

    OpenAIRE

    Austin, Annie; Cox, Jayne; Barnett, Julia; Thomas, Christine

    2011-01-01

    The ‘Exploring catalyst behaviours’ project continues Defra’s programme of research designed to develop a deeper understanding of pro-environmental behaviour. The research, conducted by Brook Lyndhurst, Dr Julie Barnett of the University of Surrey and Dr Christine Thomas of the Open University, feeds into the body of evidence that is guiding Defra and other stakeholders in developing policy, communications and other interventions to galvanise public action on the environment.The aim of the pr...

  12. 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.

  13. Regeneration of LOHC dehydrogenation catalysts: In-situ IR spectroscopy on single crystals, model catalysts, and real catalysts from UHV to near ambient pressure

    Science.gov (United States)

    Amende, Max; Kaftan, Andre; Bachmann, Philipp; Brehmer, Richard; Preuster, Patrick; Koch, Marcus; Wasserscheid, Peter; Libuda, Jörg

    2016-01-01

    The Liquid Organic Hydrogen Carrier (LOHC) concept offers an efficient route to store hydrogen using organic compounds that are reversibly hydrogenated and dehydrogenated. One important challenge towards application of the LOHC technology at a larger scale is to minimize degradation of Pt-based dehydrogenation catalysts during long-term operation. Herein, we investigate the regeneration of Pt/alumina catalysts poisoned by LOHC degradation. We combine ultrahigh vacuum (UHV) studies on Pt(111), investigations on well-defined Pt/Al2O3 model catalysts, and near-ambient pressure (NAP) measurements on real core⿿shell Pt/Al2O3 catalyst pellets. The catalysts were purposely poisoned by reaction with the LOHC perhydro-dibenzyltoluene (H18-MSH) and with dicyclohexylmethane (DCHM) as a simpler model compound. We focus on oxidative regeneration under conditions that may be applied in real dehydrogenation reactors. The degree of poisoning and regeneration under oxidative reaction conditions was quantified using CO as a probe molecule and measured by infrared reflection-absorption spectroscopy (IRAS) and diffuse reflectance Fourier transform IR spectroscopy (DRIFTS) for planar model systems and real catalysts, respectively. We find that regeneration strongly depends on the composition of the catalyst surface. While the clean surface of a poisoned Pt(111) single crystal is fully restored upon thermal treatment in oxygen up to 700 K, contaminated Pt/Al2O3 model catalyst and core⿿shell pellet were only partially restored under the applied reaction conditions. Whereas partial regeneration on facet-like sites on supported catalysts is more facile than on Pt(111), carbonaceous deposits adsorbed at low-coordinated defect sites impede full regeneration of the Pt/Al2O3 catalysts.

  14. Steam reforming catalyst

    Science.gov (United States)

    Kramarz, Kurt W.; Bloom, Ira D.; Kumar, Romesh; Ahmed, Shabbir; Wilkenhoener, Rolf; Krumpelt, Michael

    2001-01-01

    A method of forming a hydrogen rich gas from a source of hydrocarbon fuel. A vapor of the hydrocarbon fuel and steam is brought in contact with a two-part catalyst having a dehydrogenation powder portion and an oxide-ion conducting powder portion at a temperature not less than about 770.degree.C. for a time sufficient to generate the hydrogen rich. The H.sub.2 content of the hydrogen gas is greater than about 70 percent by volume. The dehydrogenation portion of the catalyst includes a group VIII metal, and the oxide-ion conducting portion is selected from a ceramic oxide from the group crystallizing in the fluorite or perovskite structure and mixtures thereof. The oxide-ion conducting portion of the catalyst is a ceramic powder of one or more of ZrO.sub.2, CeO.sub.2, Bi.sub.2 O.sub.3, (BiVO).sub.4, and LaGaO.sub.3.

  15. Ruthenium-Aryloxide Catalysts for Olefin Metathesis

    Science.gov (United States)

    Monfette, Sebastien; Blacquiere, Johanna M.; Conrad, Jay C.; Beach, Nicholas J.; Fogg, Deryn E.

    : Advances in design of ruthenium aryloxide catalysts for olefin metathesis are described. The target complexes are accessible on reaction of RuCl2(NHC)(py)2 (CHPh) (NHC - N-heterocyclic carbene) with electron-deficient, monodentate aryl- oxides, or aryloxides that yield small, rigid chelate rings. The best of these catalysts offer activity comparable to or greater than that of the parent chloride (Grubbs) systems in ring-closing metathesis (RCM). Preliminary studies of the electronic nature of the Ru-X bond suggest that the metal center is more electropositive in the aryloxide complexes than in the Grubbs systems.

  16. CATALYSTS NHI Thermochemical Systems FY 2009 Year-End Report

    Energy Technology Data Exchange (ETDEWEB)

    Daniel M. Ginosar

    2009-09-01

    , development and testing of metal oxide based H2SO4 catalysts, support of the ILS for catalyst studies, conducting a long term catalyst stability test at anticipated operating temperatures and pressures, and developing capabilities for conducting pressurized catalyst tests.

  17. Homogeneous and heterogenized iridium water oxidation catalysts

    Science.gov (United States)

    Macchioni, Alceo

    2014-10-01

    The development of an efficient catalyst for the oxidative splitting of water into molecular oxygen, protons and electrons is of key importance for producing solar fuels through artificial photosynthesis. We are facing the problem by means of a rational approach aimed at understanding how catalytic performance may be optimized by the knowledge of the reaction mechanism of water oxidation and the fate of the catalytic site under the inevitably harsh oxidative conditions. For the purposes of our study we selected iridium water oxidation catalysts, exhibiting remarkable performance (TOF > 5 s-1 and TON > 20000). In particular, we recently focused our attention on [Cp*Ir(N,O)X] (N,O = 2-pyridincarboxylate; X = Cl or NO3) and [IrCl(Hedta)]Na water oxidation catalysts. The former exhibited a remarkable TOF whereas the latter showed a very high TON. Furthermore, [IrCl(Hedta)]Na was heterogenized onto TiO2 taking advantage of the presence of a dandling -COOH functionality. The heterogenized catalyst maintained approximately the same catalytic activity of the homogeneous analogous with the advantage that could be reused many times. Mechanistic studies were performed in order to shed some light on the rate-determining step and the transformation of catalysts when exposed to "oxidative stress". It was found that the last oxidative step, preceding oxygen liberation, is the rate-determining step when a small excess of sacrificial oxidant is used. In addition, several intermediates of the oxidative transformation of the catalyst were intercepted and characterized by NMR, X-Ray diffractometry and ESI-MS.

  18. 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...

  19. 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

  20. Gas-phase polymerization of propylene with a highly active catalyst.

    NARCIS (Netherlands)

    Samson, J.J.C.; Samson, Job Jan C.; van Middelkoop, Bart; van Middelkoop, B.; Weickert, G.; Westerterp, K.R.

    1999-01-01

    The polymerization of propylene in the gas phase has been studied with the same high-activity catalyst as was used for liquid-phase polymerizations in earlier work. Catalyst injection, the influence of the support bed, and precontacting of the catalyst with the cocatalyst and the electron donor have

  1. Efficient Deprotection of Phenol Methoxymethyl Ethers Using a Solid Acid Catalyst with Wells-Dawson Structure

    Directory of Open Access Journals (Sweden)

    H. Thomas

    2001-11-01

    Full Text Available Deprotection of various phenols from their respective methoxymethyl ethers using an heteropolyacid catalyst was studied. The catalyst was the Wells-Dawson heteropolyacid, used both in bulk or supported on silica. Yields were high to quantitative after less than one hour reaction time and the catalyst was easily recoverable and reusable.

  2. Pd-Diimine : A Highly Selective Catalyst System for the Base-Free Oxidative Heck Reaction

    NARCIS (Netherlands)

    Gottumukkala, Aditya L.; Teichert, Johannes F.; Heijnen, Donis; Eisink, Niek; van Dijk, Simon; Ferrer, Catalina; van den Hoogenband, Adri; Minnaard, Adriaan J.

    2011-01-01

    Pd(OAc)(2)/3 is an efficient catalyst system for the base-free oxidative Heck reaction that outperforms the currently available catalysts for the more challenging substrates studied. The catalyst system is highly selective, and works at room temperature with dioxygen as the oxidant.

  3. Coupling of Carbon Dioxide with Epoxides Efficiently Catalyzed by Thioether-Triphenolate Bimetallic Iron(III) Complexes: Catalyst Structure-Reactivity Relationship and Mechanistic DFT Study

    KAUST Repository

    Della Monica, Francesco

    2016-08-25

    A series of dinuclear iron(III)I complexes supported by thioether-triphenolate ligands have been prepared to attain highly Lewis acidic catalysts. In combination with tetrabutylammonium bromide (TBAB) they are highly active catalysts in the synthesis of cyclic organic carbonates through the coupling of carbon dioxide to epoxides with the highest initial turnover frequencies reported to date for the conversion of propylene oxide to propylene carbonate for iron-based catalysts (5200h-1; 120°C, 2MPa, 1h). In particular, these complexes are shown to be highly selective catalysts for the coupling of carbon dioxide to internal oxiranes affording the corresponding cyclic carbonates in good yield and with retention of the initial stereochemical configuration. A density functional theory (DFT) investigation provides a rational for the relative high activity found for these Fe(III) complexes, showing the fundamental role of the hemilabile sulfur atom in the ligand skeleton to promote reactivity. Notably, in spite of the dinuclear nature of the catalyst precursor only one metal center is involved in the catalytic cycle. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. A Phenomenological Study on the Synergistic Role of Precious Metals in the Steam Reforming of Logistic Fuels on Trimetal-Supported Catalysts

    Directory of Open Access Journals (Sweden)

    Abdul-Majeed Azad

    2010-01-01

    Full Text Available Fuel processors are required to convert sulfur-laden logistic fuels (jet fuels, diesel, and coal into fuel cell quality hydrogen-rich reformate with little or no sulfur for extended periods. Sulfur poisons and deactivates the reforming catalyst, therefore, sulfur-tolerant catalysts ought to be developed. In this paper, the development, characterization, and evaluation of a series of nanoscale ceria-supported reforming catalysts containing three noble metals in low concentration (1 wt% ≤ total metal loading ≤ 1.33 wt% for the steam-reforming of kerosene (a JP-8 surrogate are reported. Their performance is quantified in terms of H2 yield, tolerance towards sulfur in the fuel, and the on-stream stability and compared with that of monometal and bimetal analogs under identical conditions. Due to the inherent cooperative synergy, a trimetal catalyst was found far superior to its mono- and bimetallic analog containing same amount of the precious metal loading in terms of quality of the reformate (measured by H2 level in steady-state as well as the catalyst longevity on-stream prior to deactivation. At the same time a mechanistic correlation between the distinct role of a given precious metal and the extent of its loading in each of the formulations and quality of the corresponding desulfurized H2-rich reformate was discovered.

  5. Regeneration of LOHC dehydrogenation catalysts: In-situ IR spectroscopy on single crystals, model catalysts, and real catalysts from UHV to near ambient pressure

    Energy Technology Data Exchange (ETDEWEB)

    Amende, Max, E-mail: max.amende@fau.de [Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); Kaftan, Andre, E-mail: andre.kaftan@fau.de [Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); Bachmann, Philipp, E-mail: philipp.bachmann@fau.de [Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); Brehmer, Richard, E-mail: richard.brehmer@fau.de [Lehrstuhl für Chemische Reaktionstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); Preuster, Patrick, E-mail: patrick.preuster@fau.de [Lehrstuhl für Chemische Reaktionstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); Koch, Marcus, E-mail: marcus.koch@crt.cbi.uni-erlangen.de [Lehrstuhl für Chemische Reaktionstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen (Germany); and others

    2016-01-01

    Graphical abstract: - Highlights: • We examine the regeneration of Pt-based catalysts poisoned by LOHC degradation. • A microscopic mechanism of the removal of degradation products from Pt is proposed. • Results of our UHV studies on model catalysts are transferred to real catalysis. • Oxidative regeneration of Pt/alumina is possible under mild conditions (600 K). • The degree and temperature regime of regeneration depends on the catalyst morphology. - Abstract: The Liquid Organic Hydrogen Carrier (LOHC) concept offers an efficient route to store hydrogen using organic compounds that are reversibly hydrogenated and dehydrogenated. One important challenge towards application of the LOHC technology at a larger scale is to minimize degradation of Pt-based dehydrogenation catalysts during long-term operation. Herein, we investigate the regeneration of Pt/alumina catalysts poisoned by LOHC degradation. We combine ultrahigh vacuum (UHV) studies on Pt(111), investigations on well-defined Pt/Al{sub 2}O{sub 3} model catalysts, and near-ambient pressure (NAP) measurements on real core–shell Pt/Al{sub 2}O{sub 3} catalyst pellets. The catalysts were purposely poisoned by reaction with the LOHC perhydro-dibenzyltoluene (H18-MSH) and with dicyclohexylmethane (DCHM) as a simpler model compound. We focus on oxidative regeneration under conditions that may be applied in real dehydrogenation reactors. The degree of poisoning and regeneration under oxidative reaction conditions was quantified using CO as a probe molecule and measured by infrared reflection-absorption spectroscopy (IRAS) and diffuse reflectance Fourier transform IR spectroscopy (DRIFTS) for planar model systems and real catalysts, respectively. We find that regeneration strongly depends on the composition of the catalyst surface. While the clean surface of a poisoned Pt(111) single crystal is fully restored upon thermal treatment in oxygen up to 700 K, contaminated Pt/Al{sub 2}O{sub 3} model catalyst and

  6. 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.

  7. A convenient method for preparation of 2-amino-4,6-diphenylnicotinonitrile using HBF4 as an efficient catalyst via an anomeric based oxidation: A joint experimental and theoretical study

    Science.gov (United States)

    Zolfigol, Mohammad Ali; Kiafar, Mahya; Yarie, Meysam; Taherpour, Avat(Arman); Fellowes, Thomas; Nicole Hancok, Amber; Yari, Ako

    2017-06-01

    Experimental and computational studies in the synthesis of 2-amino-4,6-diphenylnicotinonitrile using HBF4 as an oxidizing promoter catalyst under mild and solvent free conditions were carried out. The suggested anomeric based oxidation (ABO) mechanism is supported by experimental and theoretical evidence. The theoretical study shows that the intermediate isomers with 5R- and 5S- chiral positions have suitable structures for the aromatization through an anomeric based oxidation in the final step of the mechanistic pathway.

  8. Fischer-Tropsch-Type Production of Organic Materials in the Solar Nebula: Studies Using Graphite Catalysts and Measuring the Trapping of Noble Gases

    Science.gov (United States)

    Nuth, Joseph A., III; Ferguson, Frank T.; Lucas, Christopher; Kimura, Yuki; Hohenberg, Charles

    2009-01-01

    The formation of abundant carbonaceous material in meteorites is a long standing problem and an important factor in the debate on the potential for the origin of life in other stellar systems. The Fischer-Tropsch-type (FTT) catalytic reduction of CO by hydrogen was once the preferred model for production of organic materials in the primitive solar nebula. We have demonstrated that many grain surfaces can catalyze both FTT and HB-type reactions, including amorphous iron and magnesium silicates, pure silica smokes as well as several minerals. Graphite is not a particularly good FTT catalyst, especially compared to iron powder or to amorphous iron silicate. However, like other silicates that we have studied, it gets better with exposure to CO. N2 and H2 over time: e.g., after formation of a macromolecular carbonaceous layer on the surfaces of the underlying gains. While amorphous iron silicates required only 1 or 2 experimental runs to achieve steady state reaction rates, graphite only achieved steady state after 6 or more experiments. We will present results showing the catalytic action of graphite grains increasing with increasing number of experiments and will also discuss the nature of the final "graphite" grains aster completion of our experiments.

  9. Estudio de la síntesis de acetato de butilo 1. Selección del Caralizador Study of the butyl acetate synthesis - 1. Catalyst selection

    Directory of Open Access Journals (Sweden)

    Carballo Suárez Luis María

    2004-04-01

    Full Text Available En este trabajo se realizó un estudio de selección, a escala de laboratorio, sobre ocho agentes catalíticos para la reacción de esterificación de ácido acético y butanol (siete resinas de intercambio catiónico y una matriz zeolitíca. Tomando en cuenta algunos parámetros fisicoquímicos, como los pretratamientos requeridos para la activación, la acidez, la resistencia térmica, el desempeño en reacción, etc, se encontró que las resinas de intercambio macroporosas son los catalizadores más eficientes específicamente la resina Lewatit K-2431.In this work, a laboratory scale selection study over eight catalytic agents was made, in the acetic acid and butyl alcohol esterification reaction (seven lon exchange resins and a zeolytic solid. Considering some physicochemical characteristics as the activation pre-treating requirements, acidity, thermal stability, reaction performance, etc., it was found that macroporous ion exchange resins are the most efficient catalysts, especially Lewatit K-2431 resin.

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

    KAUST Repository

    Bahri-Laleh, Naeimeh

    2012-11-01

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

  11. Study of CeO₂ Modified AlNi Mixed Pillared Clays Supported Palladium Catalysts for Benzene Adsorption/Desorption-Catalytic Combustion.

    Science.gov (United States)

    Li, Jingrong; Zuo, Shufeng; Yang, Peng; Qi, Chenze

    2017-08-15

    A new functional AlNi-pillared clays (AlNi-PILC) with a large surface area and pore volume was synthesized. The performance of adsorption/desorption-catalytic combustion over CeO 2- modified Pd/AlNi-PILC catalysts was also studied. The results showed that the d 001 -value and specific surface area ( S BET ) of AlNi-PILC reached 2.11 nm and 374.8 m²/g, respectively. The large S BET and the d 001 -value improved the high capacity for benzene adsorption. Also, the strong interaction between PdCe mixed oxides and AlNi-PILC led to the high dispersion of PdO and CeO₂ on the support, which was responsible for the high catalytic performance. Especially, 0.2% Pd/12.5% Ce/AlNi-PILC presented high performance for benzene combustion at 240 °C and high CO₂ selectivity. Also, the combustion temperatures were lower compared to the desorption temperatures, which demonstrated that it could accomplish benzene combustion during the desorption process. Furthermore, its activity did not decrease after continuous reaction for 1000 h in dry air, and it also displayed good resistance to water and the chlorinated compound, making it a promising catalytic material for the elimination of volatile organic compounds.

  12. The conversion of CO2 and CH4 to acetic acid over the Au-exchanged ZSM-5 catalyst: a density functional theory study.

    Science.gov (United States)

    Panjan, Wasinee; Sirijaraensre, Jakkapan; Warakulwit, Chompunuch; Pantu, Piboon; Limtrakul, Jumras

    2012-12-28

    The direct conversion of methane and carbon dioxide to acetic acid is one of the most challenging research topics. Using the density functional theory (M06-L) the study reveals the catalytic activity of the Au(I)-ZSM-5 zeolite in this reaction. The Au(I)-ZSM-5 is represented by a 34T quantum cluster model. The activation of the C-H bond over the Au-ZSM-5 zeolite would readily take place via the homolytic σ-bond activation with an energy barrier of 10.5 kcal mol(-1), and subsequent proton transfer from the Au cation to the zeolitic oxygen, yielding the stable methyl-gold complex adsorbed on the zeolite Brønsted acid. The conversion of CO(2) on this bi-functional catalyst involves the Brønsted acid site playing a role in the protonation of CO(2) and the methyl-gold complex acting as a methylating agent. The activation energy of 52.9 kcal mol(-1) is predicted.

  13. Sulfonated polynaphthalene as an effective and reusable catalyst for the one-pot preparation of amidoalkyl naphthols: DFT and spectroscopic studies

    Science.gov (United States)

    Pourmousavi, Seied Ali; Moghimi, Parvin; Ghorbani, Fatemeh; Zamani, Mehdi

    2017-09-01

    Sulfonated polynaphthalene (S-PNP) as a carbon-based solid acid efficiently catalyzed the one-pot three-component synthesis of amidoalkyl naphthols. The three-component process of substituted aryl aldehydes, 2-naphthol, and amide (benzamide and acetamide) or urea in the presence of S-PNP under thermal solvent-free conditions is described. Short reaction times, high yields and easy work-up are the advantages of this protocol. Furthermore, the catalyst can be readily recycled and reused without obvious significant loss of activity. Also, density functional theory (DFT) with the aid of M06-2X and B3LYP methods was used for studying of the optimized structure, molecular orbitals, electrostatic potential (ESP) map and spectroscopic analysis of some selected amidoalkyl naphthols. The thermochemical parameters of reactions including enthalpy, internal energy, entropy and Gibbs free energy were also investigated. The theoretically calculated infrared (IR) and 1H nuclear magnetic resonance (NMR) spectra of title compounds were compared to the experimental data. Based on the results, the synthesis of amidoalkyl naphthols is exothermic. A good consistency between the calculated and observed spectral data was found.

  14. 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.

  15. 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.

  16. 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.

  17. Catalysts Efficiency Evaluation by using CC Analysis Test

    Directory of Open Access Journals (Sweden)

    Arina Negoitescu

    2011-10-01

    Full Text Available The study emphasizes the necessity of the catalysts efficiency testing. Diagnosis systems using lambda probes are based on the capacity of the catalyst oxygen storage. Comparing the lambda probe signals upstream and downstream of catalyst provides an indication on catalyst activity, although the correlation between oxygen storage capacity and catalyst efficiency is still difficult. Diagnosis for the 1.4 Renault Clio Symbol was accomplished in the Road Vehicles Lab at the Politehnica University of Timisoara using AVL Dicom 4000. The tests showed that the engine worked with lean mixture being necessary a fuel mixture correction calculated by the control unit ECU. A compensation of 0.14 % vol is required for the engine correct operation and emissions integration within permissible limits

  18. Methane decomposition on Fe-Cu Raney-type catalysts

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-10-15

    The decomposition of methane into hydrogen and carbon was studied on Fe-Cu catalysts of Raney-type. The activity of the catalysts was assessed by comparing the experimental conversions with the calculated equilibrium conversions for each set of experimental conditions. The stability of the catalysts was assessed by comparing the maximum conversions with the conversions at the end of 5-hour tests. The carbon deposits obtained consist mostly of carbon nanofibers. Good results were obtained when the Fe-Cu Raney-type systems were thermally treated in situ at 600 C, as a result of incipient alloy formation. These catalysts showed higher stability than the monometallic Raney-Fe catalysts. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-09-15

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

  20. Hydrogenation of Tetralin over Supported Ni and Ir Catalysts

    Directory of Open Access Journals (Sweden)

    Dipali P. Upare

    2013-01-01

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

  1. 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.

  2. Catalyst. Volume 10, Number 3, Spring 2009

    Science.gov (United States)

    Ryan, Barbara E., Ed.

    2009-01-01

    "Catalyst" is a publication of the U.S. Department of Education's Higher Education Center for Alcohol and Other Drug Abuse and Violence Prevention. This issue contains the following articles: (1) The National Study of Student Hazing Initial Findings; (2) The Social Norms Marketing Research Project--An Update; (3) Message From William…

  3. Pt/C Fuel Cell Catalyst Degradation

    DEFF Research Database (Denmark)

    Zana, Alessandro

    This thesis investigates the degradation behavior of Pt/C catalysts under simulated automotive conditions. By using the “tool box” synthesis method the Pt loading has been changed from low to high Pt loadings, therefore permitting to study the role of Pt on the degradation of high surface area (H...

  4. Sintering of nickel steam reforming catalysts

    DEFF Research Database (Denmark)

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

    2014-01-01

    . 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...

  5. Catalysts by Design: The Power of Theory

    Energy Technology Data Exchange (ETDEWEB)

    Hammes-Schiffer, Sharon

    2017-03-21

    Theoretical design of effective catalysts, in conjunction with the identification of guiding design principles and strategies, is a Holy Grail in Chemistry. Although further progress will benefit from additional computational advances, theoretical studies have already enhanced the design of molecular electrocatalysts, photocatalysts, and enzymes.

  6. A Study of Deactivating Carbon Species during Methanation on a Ni/Al2O3 Catalyst

    DEFF Research Database (Denmark)

    Olesen, Sine Ellemann

    are prone to deactivate due to sintering and carbon deposition. The latter process is not well understood and thus, this work attempted to further the research in low temperature carbon formation. In order to obtain fundamental knowledge, the experimental setup had to be free of impurities and great care......This Ph.D. thesis describes the research and ndings from experimental testing of a methanation catalyst and the characterisation of said catalyst. Methanation is the conversion of syngas (CO and H2) typically from coal or biomass to methane and water. Methane is the biggest constituent of...

  7. 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.

  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. 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.

  10. 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...

  11. Preliminary study on optimization of pH, oxidant and catalyst dose for high COD content: solar parabolic trough collector

    National Research Council Canada - National Science Library

    Singh, Chandan; Chaudhary, Rubina; Gandhi, Kavita

    2013-01-01

    In the present study, solar photocatalytic oxidation has been investigated through laboratory experiments as an alternative to conventional secondary treatment for the organic content reduction of high COD wastewater...

  12. Effect of Electric Discharge on Properties of Nano-Particulate Catalyst for Plasma-Catalysis.

    Science.gov (United States)

    Lee, Chung Jun; Kim, Jip; Kim, Taegyu

    2016-02-01

    Heterogeneous catalytic processes have been used to produce hydrogen from hydrocarbons. However, high reforming temperature caused serious catalyst deteriorations and low energy efficiency. Recently, a plasma-catalyst hybrid process was used to reduce the reforming temperature and to improve the stability and durability of reforming catalysts. Effect of electric discharges on properties of nanoparticulate catalysts for plasma-catalysis was investigated in the present study. Catalyst-bed porosity was varied by packing catalyst beads with the different size in a reactor. Discharge power and onset voltage of the plasma were measured as the catalyst-bed porosity was varied. The effect of discharge voltage, frequency and voltage waveforms such as the sine, pulse and square was investigated. We found that the optimal porosity of the catalyst-bed exists to maximize the electric discharge. At a low porosity, the electric discharge was unstable to be sustained because the space between catalysts got narrow nearly close to the sheath region. On the other hand, at a high porosity, the electric discharge became weak because the plasma was not sufficient to interact with the surface of catalysts. The discharge power increased as the discharge voltage and frequency increased. The square waveform was more efficient than the sine and pulse one. At a high porosity, however, the effect of the voltage waveform was not considerable because the space between catalysts was too large for plasma to interact with the surface of catalysts.

  13. Catalyst Activity Comparison of Alcohols over Zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Ramasamy, Karthikeyan K.; Wang, Yong

    2013-01-01

    Alcohol transformation to transportation fuel range hydrocarbon on HZSM-5 (SiO2 / Al2O3 = 30) catalyst was studied at 360oC and 300psig. Product distributions and catalyst life were compared using methanol, ethanol, 1-propanol or 1-butanol as a feed. The catalyst life for 1-propanol and 1-butanol was more than double compared to that for methanol and ethanol. For all the alcohols studied, the product distributions (classified to paraffin, olefin, napthene, aromatic and naphthalene compounds) varied with time on stream (TOS). At 24 hours TOS, liquid product from 1-propanol and 1-butanol transformation primarily contains higher olefin compounds. The alcohol transformation process to higher hydrocarbon involves a complex set of reaction pathways such as dehydration, oligomerization, dehydrocyclization, and hydrogenation. Compared to ethylene generated from methanol and ethanol, oligomerization of propylene and butylene has a lower activation energy and can readily take place on weaker acidic sites. On the other hand, dehydrocyclization of propylene and butylene to form the cyclic compounds requires the sits with stronger acid strength. Combination of the above mentioned reasons are the primary reasons for olefin rich product generated in the later stage of the time on stream and for the extended catalyst life time for 1 propanol and 1 butanol compared to methanol and ethanol conversion over HZSM-5.

  14. Stability of a Bifunctional Cu-Based Core@Zeolite Shell Catalyst for Dimethyl Ether Synthesis Under Redox Conditions Studied by Environmental Transmission Electron Microscopy and In Situ X-Ray Ptychography.

    Science.gov (United States)

    Baier, Sina; Damsgaard, Christian D; Klumpp, Michael; Reinhardt, Juliane; Sheppard, Thomas; Balogh, Zoltan; Kasama, Takeshi; Benzi, Federico; Wagner, Jakob B; Schwieger, Wilhelm; Schroer, Christian G; Grunwaldt, Jan-Dierk

    2017-06-01

    When using bifunctional core@shell catalysts, the stability of both the shell and core-shell interface is crucial for catalytic applications. In the present study, we elucidate the stability of a CuO/ZnO/Al2O3@ZSM-5 core@shell material, used for one-stage synthesis of dimethyl ether from synthesis gas. The catalyst stability was studied in a hierarchical manner by complementary environmental transmission electron microscopy (ETEM), scanning electron microscopy (SEM) and in situ hard X-ray ptychography with a specially designed in situ cell. Both reductive activation and reoxidation were applied. The core-shell interface was found to be stable during reducing and oxidizing treatment at 250°C as observed by ETEM and in situ X-ray ptychography, although strong changes occurred in the core on a 10 nm scale due to the reduction of copper oxide to metallic copper particles. At 350°C, in situ X-ray ptychography indicated the occurrence of structural changes also on the µm scale, i.e. the core material and parts of the shell undergo restructuring. Nevertheless, the crucial core-shell interface required for full bifunctionality appeared to remain stable. This study demonstrates the potential of these correlative in situ microscopy techniques for hierarchically designed catalysts.

  15. A catalyst for system change: a case study of child health network formation, evolution and sustainability in Canada.

    Science.gov (United States)

    McPherson, Charmaine; Ploeg, Jenny; Edwards, Nancy; Ciliska, Donna; Sword, Wendy

    2017-02-01

    The purpose of this study was to examine key processes and supportive and inhibiting factors involved in the development, evolution, and sustainability of a child health network in rural Canada. This study contributes to a relatively new research agenda aimed at understanding inter-organizational and cross-sectoral health networks. These networks encourage collaboration focusing on complex issues impacting health - issues that individual agencies cannot effectively address alone. This paper presents an overview of the study findings. An explanatory qualitative case study approach examined the Network's 13-year lifespan. Data sources were documents and Network members, including regional and 71 provincial senior managers from 11 child and youth service sectors. Data were collected through 34 individual interviews and a review of 127 documents. Interview data were analyzed using framework analysis methods; Prior's approach guided document analysis. Three themes related to network development, evolution and sustainability were identified: (a) Network relationships as system triggers, (b) Network-mediated system responsiveness, and (c) Network practice as political. Study findings have important implications for network organizational development, collaborative practice, interprofessional education, public policy, and public system responsiveness research. Findings suggest it is important to explicitly focus on relationships and multi-level socio-political contexts, such as supportive policy environments, in understanding health networks. The dynamic interplay among the Network members; central supportive and inhibiting factors; and micro-, meso-, and macro-organizational contexts was identified.

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

    Science.gov (United States)

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

    2015-07-01

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

  17. Nano Catalysts for Diesel Engine Emission Remediation

    Energy Technology Data Exchange (ETDEWEB)

    Narula, Chaitanya Kumar [ORNL; Yang, Xiaofan [ORNL; Debusk, Melanie Moses [ORNL; Mullins, David R [ORNL; Mahurin, Shannon Mark [ORNL; Wu, Zili [ORNL

    2012-06-01

    conditions were provided by our collaborators at John Deere Power Systems. Among various zeolites reported here, CuFe-SSZ-13 offers the best NO{sub x} conversion activity in 150-650 C range and is hydrothermally stable when tested under accelerated aging conditions. It is important to note that Cu-SSZ-13 is now a commercial catalyst for NO{sub x} treatment on diesel passenger vehicles. Thus, our catalyst performs better than the commercial catalyst under fast SCR conditions. We initially focused on fast SCR tests to enable us to screen catalysts rapidly. Only the catalysts that exhibit high NO{sub x} conversion at low temperatures are selected for screening under varying NO{sub 2}:NO{sub x} ratio. The detailed tests of CuFe-SSZ-13 show that CuFe-SSZ-13 is more effective than commercial Cu-SSZ-13 even at NO{sub 2}:NO{sub x} ratio of 0.1. The mechanistic studies, employing stop-flow diffuse reflectance FTIR spectroscopy (DRIFTS), suggest that high concentration of NO{sup +}, generated by heterobimetallic zeolites, is probably responsible for their superior low temperature NO{sub x} activity. The results described in this report clearly show that we have successfully completed the first step in a new emission treatment catalyst which is synthesis and laboratory testing employing simulated exhaust. The next step in the catalyst development is engine testing. Efforts are in progress to obtain follow-on funding to carry out scale-up and engine testing to facilitate commercialization of this technology.

  18. A comparative DFT study on the CO oxidation reaction over Al- and Ge-embedded graphene as efficient metal-free catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Esrafili, Mehdi D., E-mail: esrafili@maragheh.ac.ir; Nematollahi, Parisa; Abdollahpour, Hadi

    2016-08-15

    Highlights: • The oxidation of CO by O{sub 2} molecule is investigated over Al- and Ge-embedded graphene. • The first reaction pathway of the CO oxidation over both surfaces should proceed with the ER mechanism. • Ge-embedded graphene can be used as a more efficient catalyst for oxidation of CO than Al- embedded graphene. - Abstract: In the present study, by means of density functional theory (DFT) calculations, the catalytic oxidation of CO by O{sub 2} molecule is investigated over Al- and Ge-embedded graphene. The large atomic radius of these dopant atoms can induce a local surface curvature and modulate the electronic structure properties of the graphene sheet through the charge redistribution. It is found that the adsorption of molecular O{sub 2} over Al- or Ge-embedded graphene is stronger than that of CO molecule. The CO oxidation reaction by molecular O{sub 2} on Al- and Ge-embedded graphene is comparably studied. The results indicate that a two-step process can occur, namely, CO + O{sub 2} → CO{sub 2} + O{sub ads} and CO + O{sub ads} → CO{sub 2}. Furthermore, the computed activation energy (E{sub act}) for the first reaction on Ge-doped graphene is lower than that of Al-doped one, and the formation of second CO{sub 2} molecule on both surfaces can occur rapidly due to its low energy barrier (0.1 eV).

  19. Insights into the asymmetric heterogeneous catalysis in porous organic polymers: constructing a TADDOL-embedded chiral catalyst for studying the structure-activity relationship.

    Science.gov (United States)

    An, Wan-Kai; Han, Man-Yi; Wang, Chang-An; Yu, Si-Min; Zhang, Yuan; Bai, Shi; Wang, Wei

    2014-08-25

    Construction of porous organic polymers (POPs) as asymmetric catalysts remains as an important but challenging task. Herein, we exploit the "bottom-up" strategy to facilely synthesize an α,α,α',α'-tetraaryl-1,3-dioxolane-4,5-dimethanol (TADDOL)-based chiral porous polymer (TADDOL-CPP) for highly efficient asymmetric catalysis. Constructed through the covalent linkages among the three-dimensional rigid monomers, TADDOL-CPP possesses hierarchical porous structure, high Brunauer-Emmett-Teller (BET) surface area, together with abundant and uniformly-distributed chiral sites. In the presence of [Ti(OiPr)4], TADDOL-CPP acts as a highly efficient and recyclable catalyst in the asymmetric addition of diethylzinc (Et2Zn) to aromatic aldehydes. Based on the direct observation of the key intermediates, the reaction mechanism has been revealed by solid-state (13)C magic-angle spinning (MAS) NMR spectroscopy. In combination with the catalytic testing results, characterization on the working catalyst provides further information for understanding the structure-activity relationship. We suggest that the catalytic activity of TADDOL-CPP is largely affected by the structural rigidity, cooperative catalysis, local chiral environment, and hierarchical porous framework. We expect that the information obtained herein will benefit to the designed synthesis of robust POP catalysts toward practical applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Study on the decomposition of trace benzene over V2O5-WO3/TiO2-based catalysts in simulated flue gas

    Science.gov (United States)

    Commercial and laboratory-prepared V2O5–WO3/TiO2-based catalysts with different compositions were tested for catalytic decomposition of chlorobenzene (ClBz) in simulated flue gas. Resonance enhanced multiphoton ionization-time of flight mass spectrometry (REMPI-TOFMS) was employe...