Thermal desorption of toluene from Vanadium-containing catalysts coated onto various carriers

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Z. Zheksenbaeva

2012-12-01

Full Text Available The method temperature-programmed desorption has been studied the state of toluene on the surface-modified vanadium catalysts on different carriers. Among the investigated carriers the most active in the reaction of partial oxidation of toluene is anatase structural titanium dioxide. For the partial oxidation of toluene on modified vanadium-containing catalysts deposited on TiO2 was tested. It was found that on the catalyst 20%V2O5-5%MoO3-2%Sb2O3/TiO2 at a temperature of 673K, volume rate of 15 thousand hours-1 oxidation of toluene is 80% c yield of benzoic acid with a selectivity of  70% of 87.5%.

Hydrogen adsorption on activated carbon nanotubes with an atomic-sized vanadium catalyst investigated by electrical resistance measurements

International Nuclear Information System (INIS)

Im, Ji Sun; Yun, Jumi; Kang, Seok Chang; Lee, Sung Kyu; Lee, Young-Seak

2012-01-01

Activated multi-walled carbon nanotubes were prepared with appended vanadium as a hydrogen storage medium. The pore structure was significantly improved by an activation process that was studied using Raman spectroscopy, field emission transmission electron microscopy and pore analysis techniques. X-ray photoelectron spectroscopy and X-ray diffraction results reveal that the vanadium catalyst was introduced into the carbon nanotubes in controlled proportions, forming V 8 C 7 . The improved pore structure functioned as a path through the carbon nanotubes that encouraged hydrogen molecule adsorption, and the introduced vanadium catalyst led to high levels of hydrogen storage through the dissociation of hydrogen molecules via the spill-over phenomenon. The hydrogen storage behavior was investigated by electrical resistance measurements for the hydrogen adsorbed on a prepared sample. The proposed mechanism of hydrogen storage suggests that the vanadium catalyst increases not only the amount of hydrogen that is stored but also the speed at which it is stored. A hydrogen storage capacity of 2.26 wt.% was achieved with the activation effects and the vanadium catalyst at 30 °C and 10 MPa.

Decomposition of hydrogen peroxide on nickel oxide - vanadium pentoxide catalysts and the effect of ionizing radiation on them

International Nuclear Information System (INIS)

Mucka, V.

1984-01-01

Some physico-chemical and catalytic properties of nickel oxide-vanadium pentoxide two-component catalysts were studied over the entire concentration range of the components, using the decomposition of hydrogen peroxide in an aqueous solution as the test reaction. The two oxides were found to affect each other; this was shown by the dependences of the specific surface area, the V 4+ ion concentration, and the catalyst activity on the system composition. At low vanadium pentoxide concentrations (up to 15 mol%) the reaction took place on nickel oxide modified with vanadium pentoxide, whereas in the region of higher vanadium pentoxide concentrations the decomposition of the peroxide was catalyzed primarily in the homogeneous phase by vanadium(V) peroxide ions; in a sample with 30 mol% V 2 O 5 , trivalent vanadium also played a part. With catalysts obtained by mere mechanical mixing of the two oxides, a modified activity was observed in the region of high excess of nickel oxide. The activity of catalyst, particularly pure nickel oxide, was increased by its partial reduction and decreased by its exposure to gamma radiation if the dose was higher than 10 5 Gy. The effects observed are interpreted in terms of the concept of bivalent catalytic centres. (author)

Improved capacitance characteristics of electrospun ACFs by pore size control and vanadium catalyst.

Science.gov (United States)

Im, Ji Sun; Woo, Sang-Wook; Jung, Min-Jung; Lee, Young-Seak

2008-11-01

Nano-sized carbon fibers were prepared by using electrospinning, and their electrochemical properties were investigated as a possible electrode material for use as an electric double-layer capacitor (EDLC). To improve the electrode capacitance of EDLC, we implemented a three-step optimization. First, metal catalyst was introduced into the carbon fibers due to the excellent conductivity of metal. Vanadium pentoxide was used because it could be converted to vanadium for improved conductivity as the pore structure develops during the carbonization step. Vanadium catalyst was well dispersed in the carbon fibers, improving the capacitance of the electrode. Second, pore-size development was manipulated to obtain small mesopore sizes ranging from 2 to 5 nm. Through chemical activation, carbon fibers with controlled pore sizes were prepared with a high specific surface and pore volume, and their pore structure was investigated by using a BET apparatus. Finally, polyacrylonitrile was used as a carbon precursor to enrich for nitrogen content in the final product because nitrogen is known to improve electrode capacitance. Ultimately, the electrospun activated carbon fibers containing vanadium show improved functionality in charge/discharge, cyclic voltammetry, and specific capacitance compared with other samples because of an optimal combination of vanadium, nitrogen, and fixed pore structures.

Studies in transition metal chemistry ; V. Soluble Ziegler-type catalysts based on vanadium, part 1

NARCIS (Netherlands)

Liefde Meijer, H.J. de; Hurk, J.W.G. van den; Kerk, G.J.M. van der

1966-01-01

Experiments are described aiming at a simplification of the catalyst system originally consisting of a mixture of tetraphenyltin, aluminium bromide and vanadium tetrachloride (or vanadium oxytrichloride). It is shown that tetraphenyltin merely acts as a phenylating agent for the aluminium bromide

Application of vanadium incorporated phosphomolybdate supported on the modified kaolinin synthesis of diphenyl carbonate by oxidative carbonylation with phenol

Directory of Open Access Journals (Sweden)

Peng Meng

2017-01-01

Full Text Available Keggin-type molybdophosphoric acid, molybdophosphoric salt and vanadium incorporated molybdophosphoric salt supported on the modified kaolin (MK were investigated as redox co-catalysts for the oxidative carbonylation of phenol to diphenyl carbonate (DPC in the absence of solvent. The 20 wt.% of MnAMPV5 (one kind of vanadium incorporated molybdophosphoric salt loaded on MK showed the highest catalytic activity with the yield of 24.68% and a TON of 306, while the selectivity amounts to nearly 100% in all the carbonylation reactions. The catalysts were characterized by XRD, BET, XPS and H2-TPR. The reusability study showed that the catalysts were stable and active.

[Spectralsignatures of nickel and vanadium supported photocatalysts and their photocatalytic properties].

Science.gov (United States)

Hai, Feng; Zhang, Qian-Cheng; Wang, Zhi-Wei; Jian, Li

2011-04-01

Using SiO2, activated carbon (AC) and Al2O3 as supports, the supported photocatalysts Ni-V-O/SiO2, Ni-V-O/AC and Ni-V-O/Al2O3 were prepared by impregnation method, and their spectralsignatures were investigated. The carbonylation of methanol with CO2 under UV irradiation was used as a probe reaction to compare the photocatalytic performance of the prepared catalysts. Integrated with the testing results of carbonylation, the effects of different supports on selectivity for the carbonylation products of methyl formate (MF) and dimethyl carbonate (DMC) were discussed by pyridine-IR and UV-Vis techniques. XRD results showed that the particles of nickel and vanadium supported on SiO2 had the highest degree of dispersion. Results of pyridine-IR indicated that all catalysts retained Lewis acid sites. The acid strength was different from catalyst samples with different supports but with the same active components. The acid strengths could be arranged as follows: Ni-V-O/SiO2 > Ni-V-O/Al2 O3 > Ni-V-O/AC. Different acid strengths exhibited different influence on the selectivity of products MF and DMC of carbonylation. The surface acid strengths of catalysts were the major factor influencing the selectivity of carbonylation products.

Catalytic partial oxidation of methane over porous silica supported VO{sub x} catalysts

Energy Technology Data Exchange (ETDEWEB)

Pirovano, C.; Schoenborn, E.; Kalevaru, V.N.; Wohlrab, S.; Luecke, B.; Martin, A. [University Rostock e.V., Rostock (Germany). Leibniz Inst. for Catalysis

2011-07-01

High surface area mesoporous siliceous MCM-41 and SBA-15 materials have been used as supports to disperse vanadium oxide species using wet impregnation and incipient wetness impregnation methods. These materials were used as catalysts for the partial oxidation of methane (POM) to formaldehyde. The physico-chemical properties of the solids were studied by means of BET, DR-UV/Vis spectroscopy, Py-FTIR and TEM. The influence of support and the preparation method on the dispersion of VOx is also investigated. The catalytic properties of the catalysts were examined in a fixed bed stainless steel reactor at 923 K. So far a maximum production of formaldehyde can be detected on SBA-15 supported VOx-catalysts prepared by incipient wetness impregnation. On this V/SBA-15 material a covalent attachment of catalytic active molecular vanadium species dominates, which in turn leads to a lower activation temperature and thereby reduced over-oxidation. From the best case, the space time yield of HCHO could be reached close to 775 g{sub HCHO} Kg{sub cat}{sup -1} h{sup -1}. (orig.)

Recovery of vanadium (V) from spent catalysts used in sulfuric acid production units by acid or alkaline leaching

International Nuclear Information System (INIS)

Abdulbaki, M.; Stas, J.; Shino, O.; Asaad, K.; Al-Kassemi, H.; Al-Qabani, F.

2008-01-01

The present paper, studies the recovery of vanadium from the spent catalyst by using acidic or alkaline leaching technique. The optimal conditions of spent catalyst leaching have been studied. It has been shown that 20%(w/w) of sulfuric acid is the most suitable for leaching process at 70 Centigrade. The precipitation of vanadium using some alkaline media (Na 2 CO 3 , (NH 4 )CO 3 and NH 4 OH) has been also studied, it has been shown that ammonium hydroxide was the best at 60 degree, and iron was co-precipitated with vanadium which pollute the obtained red cake. So it is necessary to use liquid-liquid extraction technique for the separation between vanadium and iron and to have iron free red cake. (author)

Influence of phosphorus and potassium impurities on the properties of vanadium oxide supported on TiO2

NARCIS (Netherlands)

van Hengstum, A.J.; Pranger, J.; van Ommen, J.G.; Gellings, P.J.

1984-01-01

The catalytic properties of vanadium oxide catalysts supported on TiO2 from Tioxide were strongly affected by phosphorus and potassium, present as impurities in the TiO2 support. The effects observed were stronaly dependent on the type of hydrocarbon oxidised. In the oxidation of toluene to benzoic

Radiation modification of vanadium catalyst for anthracene oxidation

International Nuclear Information System (INIS)

Norek, J.; Vymetal, J.; Mucka, V.; Pospisil, M.; Cabicar, J.

1985-01-01

Vanadium pentoxide on a suitable carrier is often used as catalyst for the oxidation of anthracene in the gaseous phase to 9,10-anthraquinone. The activity and selectivity of the catalyst may be affected by irradiation. The effects were studied of gamma radiation on the properties of the catalyst where the active system was a V 2 O 5 -KOH-K 2 SO 4 mixture on a Al 2 O 3 +SiO 2 carrier. The 60 Co radiation source had an activity of 185 TBq; the carrier of the catalyst was irradiated at a dose rate of 3.05, 1.98 and 0.084 kGy/h to a total dose of 10 kGy. Irradiation increased the selectivity of the catalyst such that in the oxidation temperature optimum of 300 to 400 degC the yield of 9,10-anthraquinone increased by 4.6 to 4.8 %mol. to roughly 90 %mol.; a significant reduction of the content of acid components (phthalanhydride) in the oxidation product also occurred. This effect remained unchanged for 5 months after irradiation. A reduction of selectivity was observed at lower dose rates only in the temperature range between 400 and 480 degC. (A.K.)

Leaching of vanadium from waste V2O5-WO3/TiO2 catalyst catalyzed by functional microorganisms.

Science.gov (United States)

Wang, Shuhua; Xie, Yaling; Yan, Weifu; Wu, Xuee; Wang, Chin-Tsan; Zhao, Feng

2018-05-22

Solid wastes are currently produced in large amounts. Although bioleaching of metals from solid wastes is an economical and sustainable technology, it has seldom been used to recycle metals from abandoned catalyst. In this study, the bioleaching of vanadium from V 2 O 5 -WO 3 /TiO 2 catalyst were comprehensively investigated through five methods: Oligotrophic way, Eutrophic way, S-mediated way, Fe-mediated way and Mixed way of S-mediated and Fe-mediated. The observed vanadium bioleaching effectiveness of the assayed methods was follows: S-mediated > Mixed > Oligotrophic > Eutrophic > Fe-mediated, which yielded the maximum bioleaching efficiencies of approximately 90%, 35%, 33%, 20% and 7%, respectively. The microbial community analysis suggested that the predominant genera Acidithiobacillus and Sulfobacillus from the S-mediated bioleaching way effectively catalyzed the vanadium leaching, which could have occurred through the indirect mechanism from the microbial oxidation of S 0 . In addition, the direct mechanism, involving direct electron transfer between the catalyst and the microorganisms that attached to the catalyst surface, should also help the vanadium to be leached more effectively. Therefore, this work provides guidance for future research and practical application on the treatment of waste V 2 O 5 -WO 3 /TiO 2 catalyst. Copyright © 2018 Elsevier B.V. All rights reserved.

Influence of vanadium oxidation states on the performance of V-Mg-Al mixed-oxide catalysts for the oxidative dehydrogenation of propane

International Nuclear Information System (INIS)

Schacht, L.; Navarrete, J.; Schacht, P.; Ramirez, M. A.

2010-01-01

V-Mg-Al mixed-oxide catalysts for oxidative dehydrogenation of propane were prepared by thermal decomposition of Mg-Al-layered double hydroxides with vanadium interlayer doping. The obtained catalysts were tested for the oxidative dehydrogenation of propane, obtaining good results in catalytic activity (conversion 16.55 % and selectivity 99.97 %) Results indicated that catalytic performance of these materials depends on how vanadium is integrated in the layered structure, which is determined by the Mg/Al ratio. Vanadium interlayer doping modifies the oxidation state of vanadium and consequently catalytic properties. Surface properties were studied by X-ray photoelectron spectroscopic and diffuse reflectance, UV-visible spectroscopy, and temperature programmed reduction. The analyses provided information about the oxidation state, before and after the reaction. From these results, it is suggested that selectivity to propylene and catalytic activity depend mainly of vanadium oxidation state. (Author)

Influence of vanadium oxidation states on the performance of V-Mg-Al mixed-oxide catalysts for the oxidative dehydrogenation of propane

Energy Technology Data Exchange (ETDEWEB)

Schacht, L. [IPN, Escuela Superior de Fisica y Matematicas, Departamento de Ciencia de Materiales, Av. IPN s/n, Edificio 9, Col. Lindavista, 07738 Mexico D. F. (Mexico); Navarrete, J.; Schacht, P.; Ramirez, M. A., E-mail: pschacha@imp.m [Instituto Mexicano del Petroleo, Programa de Ingenieria Molecular, Eje Central Lazaro Cardenas No. 152, 07730 Mexico D. F. (Mexico)

2010-07-01

V-Mg-Al mixed-oxide catalysts for oxidative dehydrogenation of propane were prepared by thermal decomposition of Mg-Al-layered double hydroxides with vanadium interlayer doping. The obtained catalysts were tested for the oxidative dehydrogenation of propane, obtaining good results in catalytic activity (conversion 16.55 % and selectivity 99.97 %) Results indicated that catalytic performance of these materials depends on how vanadium is integrated in the layered structure, which is determined by the Mg/Al ratio. Vanadium interlayer doping modifies the oxidation state of vanadium and consequently catalytic properties. Surface properties were studied by X-ray photoelectron spectroscopic and diffuse reflectance, UV-visible spectroscopy, and temperature programmed reduction. The analyses provided information about the oxidation state, before and after the reaction. From these results, it is suggested that selectivity to propylene and catalytic activity depend mainly of vanadium oxidation state. (Author)

X-Ray Absorption Studies of Vanadium-Containing Metal Oxide Nanocrystals

Energy Technology Data Exchange (ETDEWEB)

Hohn, Keith, L.

2006-01-09

Metal oxide nanocrystals offer significant potential for use as catalysts or catalyst supports due to their high surface areas and unique chemical properties that result from the high number of exposed corners and edges. However, little is known about the catalytic activity of these materials, especially as oxidation catalysts. This research focused on the preparation, characterization and use of vanadium-containing nanocrystals as selective oxidation catalysts. Three vanadium-containing nanocrystals were prepared using a modified sol-gel procedure: V/MgO, V/SiO2, and vanadium phosphate (VPO). These represent active oxidation catalysts for a number of industrially relevant reactions. The catalysts were characterized by x-ray diffraction and Raman, UV-VIS, infrared and x-ray absorption spectroscopies with the goal of determining the primary structural and chemical differences between nanocrystals and microcrystals. The catalytic activity of these catalysts was also studied in oxidative dehydrogenation of butane and methanol oxidation to formaldehyde. V/MgO nanocrystals were investigated for activity in oxidative dehydrogenation of butane and compared to conventional V/MgO catalysts. Characterization of V/MgO catalysts using Raman spectroscopy and x-ray absorption spectroscopy showed that both types of catalysts contained magnesium orthovanadate at vanadium loadings below 15 weight%, but above that loading, magnesium pyrovanadate may have been present. In general, MgO nanocrystals had roughly half the crystal size and double the surface area of the conventional MgO. In oxidative dehydrogenation of butane, nanocrystalline V/MgO gave higher selectivity to butene than conventional V/MgO at the same conversion. This difference was attributed to differences in vanadium domain size resulting from the higher surface areas of the nanocrystalline support, since characterization suggested that similar vanadium phases were present on both types of catalysts. Experiments in

Effect of thermal treatment conditions on properties of vanadium molybdenum oxide catalyst in acrolein oxidation reaction to acrylic acid

International Nuclear Information System (INIS)

Gorshkova, T.P.; Tarasova, D.V.; Olen'kova, I.P.; Andrushkevich, T.V.; Nikoro, T.A.

1984-01-01

The effect of thermal treatment conditions (temperature and gas medium) on properties of vanadium molybdenum oxide catalyst in acrolein oxidation reaction to acrylic acid is investigated. It is shown that active and selective catalysts are formed in the course of thermal decomposition of the drying product of ammonium metavanadate and paramolybdate under the conditions ensuring the vanadium ion reduction up to tetravalent state with conservation of molybdenum oxidation degree equal to 6. It is possible to realize it either by treatment of the catalyst calcinated in the air flow at 300 deg by the reaction mixture at the activation stage or by gas-reducer flow treatment at 280 deg. Thermal treatment in the reducing medium of the oxidized catalyst does not lead to complete regeneration of its properties

Synthesis and Characterization of Polyethylene/Starch Nanocomposites: A Spherical Starch-Supported Catalyst and In Situ Ethylene Polymerization.

Science.gov (United States)

Zhanga, Hao; Xi, Shixia; Wang, Shuwei; Liu, Jingsheng; Yoon, Keun-Byoung; Lee, Dong-Ho; Zhang, Hexin; Zhang, Xuequan

2017-01-01

In the present article, a novel spherical starch-supported vanadium (V)-based Ziegler-Natta catalyst was synthesized. The active centers of the obtained catalyst well dispersed in the starch through the SEM-EDX analysis. The effects of reaction conditions on ethylene polymerization were studied. The synthesized catalyst exhibited high activity toward ethylene polymerization in the presence of ethylaluminium sesquichloride (EASC) cocatalyst. Interestingly, the fiber shape PE was obtained directly during the polymerization process.

Vanadium recycling in the United States in 2004

Science.gov (United States)

Goonan, Thomas G.

2011-01-01

As one of a series of reports that describe the recycling of metal commodities in the United States, this report discusses the flow of vanadium in the U.S. economy in 2004. This report includes a description of vanadium supply and demand in the United States and illustrates the extent of vanadium recycling and recycling trends. In 2004, apparent vanadium consumption, by end use, in the United States was 3,820 metric tons (t) in steelmaking and 232 t in manufacturing, of which 17 t was for the production of superalloys and 215 t was for the production of other alloys, cast iron, catalysts, and chemicals. Vanadium use in steel is almost entirely dissipative because recovery of vanadium from steel scrap is chemically impeded under the oxidizing conditions in steelmaking furnaces. The greatest amount of vanadium recycling is in the superalloy, other-alloy, and catalyst sectors of the vanadium market. Vanadium-bearing catalysts are associated with hydrocarbon recovery and refining in the oil industry. In 2004, 2,850 t of vanadium contained in alloy scrap and spent catalysts was recycled, which amounted to about 44 percent of U.S. domestic production. About 94 percent of vanadium use in the United States was dissipative (3,820 t in steel/4,050 t in steel+fabricated products).

Leaching of vanadium from sulphuric acid manufacture spent catalysts

Directory of Open Access Journals (Sweden)

García, Diego Juan

2001-02-01

Full Text Available Recovery of vanadium contained in spent catalysts from the manufacture of sulphuric acid has been studied in this work, resulting in an industrial multistage process for the treatment of them avoiding direct deposition or dumping. Characterization of supplied spent catalysts samples, confirmed vanadium levels showed in the literature. The study of variables influencing leaching process: type of leaching agent, leaching agent concentration, S/L ratio, stirring speed and temperature, allows to fix the most advantageous conditions using industrial application criterion and verifying that the process is difusión controlled. The work is completed by developing an industrial leaching cycle simulation with the aim of reproducing real performance of spent catalyst, proposing operating conditions, and verifying the non-toxic character of the final residue obtained.

En el presente trabajo se ha estudiado la recuperación del vanadio contenido en los catalizadores agotados procedentes de la fabricación del ácido sulfúrico, planteando un proceso industrial multietapa para el tratamiento de estos residuos, evitando su deposición o vertido directos. La caracterización de las muestras de catalizadores agotados disponibles confirmó los valores encontrados en la bibliografía. Se estudiaron las variables que influyen en el proceso de lixiviación (tipo de agente de lixiviación y concentración del mismo, relación S/L, velocidad de agitación y temperatura definiendo las condiciones más adecuadas desde el punto de vista industrial y verificando que el proceso está controlado por mecanismos difusionales. El trabajo se completa con la simulación de un ciclo industrial de lavado del catalizador y la verificación de la nula toxicidad de los lixiviados obtenidos por degradación del residuo final. 24 Aplicación de la resistencia de ruido al estudio de pinturas ricas en zinc Noise resistance applied to the study of zinc rich paints

Nanorod niobium oxide as powerful catalysts for an all vanadium redox flow battery.

Science.gov (United States)

Li, Bin; Gu, Meng; Nie, Zimin; Wei, Xiaoliang; Wang, Chongmin; Sprenkle, Vincent; Wang, Wei

2014-01-08

A powerful low-cost electrocatalyst, nanorod Nb2O5, is synthesized using the hydrothermal method with monoclinic phases and simultaneously deposited on the surface of a graphite felt (GF) electrode in an all vanadium flow battery (VRB). Cyclic voltammetry (CV) study confirmed that Nb2O5 has catalytic effects toward redox couples of V(II)/V(III) at the negative side and V(IV)/V(V) at the positive side to facilitate the electrochemical kinetics of the vanadium redox reactions. Because of poor conductivity of Nb2O5, the performance of the Nb2O5 loaded electrodes is strongly dependent on the nanosize and uniform distribution of catalysts on GF surfaces. Accordingly, an optimal amount of W-doped Nb2O5 nanorods with minimum agglomeration and improved distribution on GF surfaces are established by adding water-soluble compounds containing tungsten (W) into the precursor solutions. The corresponding energy efficiency is enhanced by ∼10.7% at high current density (150 mA·cm(-2)) as compared with one without catalysts. Flow battery cyclic performance also demonstrates the excellent stability of the as prepared Nb2O5 catalyst enhanced electrode. These results suggest that Nb2O5-based nanorods, replacing expensive noble metals, uniformly decorating GFs holds great promise as high-performance electrodes for VRB applications.

Vanadium-substituted heteropolyacids immobilized on amine- functionalized mesoporous MCM-41: A recyclable catalyst for selective oxidation of alcohols with H2O2

International Nuclear Information System (INIS)

Dong, Xinbo; Wang, Danjun; Li, Kebin; Zhen, Yanzhong; Hu, Huaiming; Xue, Ganglin

2014-01-01

Graphical abstract: Vanadium-substituted phosphotungstic acids are immobilized on amine- functionalized mesoporous MCM-41 and the hybrid catalyst is proved to be a highly efficient solid catalyst for the oxidation of aromatic alcohols to the corresponding carbonyl compounds with H 2 O 2 , featured by the high conversion and selectivity, easy recovery, and quite steady reuse. - Highlights: • Vanadium-substituted phosphotungstic acid immobilized on amine-functionalized mesoporous MCM-41 are prepared. • HPAs were fixed on the inner surface of mesoporous MCM-41 by chemical bonding to aminosilane groups. • The hybrid catalyst showed much higher catalytic activity than the pure HPAs. • The hybrid catalyst is a highly efficient recyclable solid catalyst for the selective oxidation of aromatic alcohols. - Abstract: New hybrid materials of vanadium-substituted phosphotungstic acids (VHPW) immobilized on amine-functionalized mesoporous MCM-41 (VHPW/MCM-41/NH 2 ) are prepared and characterized by FT-IR, XRD, N 2 adsorption, elemental analysis, SEM and TEM for their structural integrity and physicochemical properties. It is found that the structure of the heteropolyacids is retained upon immobilization over mesoporous materials. The catalytic activities of these hybrid materials are tested in the selective oxidation of alcohols to the carbonyl products with 30% aqueous H 2 O 2 as oxidant in toluene. The catalytic activities of different number of vanadium-substituted phosphotungstic acid are investigated, and among the catalysts, H 5 [PV 2 W 10 O 40 ] immobilized on amine-functionalized MCM-41 exhibits the highest activity with 97% conversion and 99% selectivity in the oxidation of benzyl alcohol to benzaldehyde. The hybrid catalyst is proved to be a highly efficient recyclable solid catalyst for the selective oxidation of aromatic alcohols to the corresponding aldehydes with H 2 O 2

Nature of active vanadium nanospecies in MCM-41 type catalysts for olefins oxidation

Energy Technology Data Exchange (ETDEWEB)

Chanquía, Corina M., E-mail: cchanquia@cab.cnea.gov.ar [Centro Atómico Bariloche, Comisión Nacional de Energía Atómica (CAB-CNEA). Av. Bustillo 9500, R8402AGP, San Carlos de Bariloche, Río Negro (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Avenida Rivadavia 1917, C1033AAJ, Ciudad Autónoma de Buenos Aires (Argentina); Cánepa, Analía L. [Centro de Investigación y Tecnología Química (CITeQ), Universidad Tecnológica Nacional, Facultad Regional Córdoba (UTN-FRC), Maestro López esq. Cruz Roja Argentina, Ciudad Universitaria, 5016, Córdoba Capital (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Avenida Rivadavia 1917, C1033AAJ, Ciudad Autónoma de Buenos Aires (Argentina); Winkler, Elin L. [Centro Atómico Bariloche, Comisión Nacional de Energía Atómica (CAB-CNEA). Av. Bustillo 9500, R8402AGP, San Carlos de Bariloche, Río Negro (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Avenida Rivadavia 1917, C1033AAJ, Ciudad Autónoma de Buenos Aires (Argentina); and others

2016-06-01

A multi-technique physicochemical investigation including UV–Vis-DRS, Raman spectroscopy, XPS, ESR and FTIRS with pyridine adsorption was performed to analyze the nature of different vanadium nanospecies present on MCM-41 type catalysts. By employing a direct hydrothermal synthesis, vanadium species were incorporated into siliceous structure mainly as tetrahedrally coordinated isolated V{sup δ+} ions, which would be located inside the wall and on the wall surface of the mesoporous channels. The coexistence of both vanadium oxidation states V{sup 4+} and V{sup 5+} was also revealed. Acidity measurements permitted to infer about the majority presence of Lewis acid sites, which increase with vanadium content. The catalytic performance of these materials was evaluated in the reaction of α-pinene oxidation with H{sub 2}O{sub 2}. The highest intrinsic activity of the sample with lower V loading was attributed to the high dispersion and efficiency of the isolated V{sup δ+} species that actuate as active sites. A mixture of reaction products arising from competitive processes of epoxidation and allylic oxidation was found. - Highlights: • Nature of vanadium nanospecies in mesoporous silicates was investigated. • From hydrothermal sol–gel synthesis, isolated V{sup δ+} sites were mainly generated. • The coexistence of both vanadium oxidation states V{sup 4+} and V{sup 5+} was revealed. • The catalytic performance was evaluated in α-pinene oxidation with H{sub 2}O{sub 2}. • The high catalytic activity is attributed to high dispersion of isolated V{sup δ+} ions.

The active component of vanadium-molybdenum catalysts for the oxidation of acrolein to acrylic acid

International Nuclear Information System (INIS)

Andrushkevich, T.V.; Kuznetsova, T.G.

1986-01-01

The catalytic properties of the vanadium-molybdenum oxide system were investigated in the oxidation of acrolein to acrylic acid. The active component of the catalyst is the compound VMo 3 O 11 , the maximum amount of which is observed at a content of 7-15 mole% V 2 O 4 . The compound VMo 3 O 11 is formed in the thermodecomposition of silicomolybdovanadium heteropoly acids or isopoly compounds, reduced with respect to vanadium, and contains V 4+ and Mo 6+ . The optimum treatment for the formation of this compound is treatment in the reaction mixture at 400 degrees C

Methanol Oxidation Using Ozone on Titania-Supported Vanadium Catalyst

Science.gov (United States)

Ozone-enhanced catalytic oxidation of methanol has been conducted at mild temperatures of 100 to 250NC using V2O5/TiO2 catalyst prepared by the sol-gel method. The catalyst was characterized using XRD, surface area measurements, and temperature-programmed desorption of methanol. ...

Studies of vanadium-phosphorus-oxygen selective oxidation catalysts by sup 31 P and sup 51 V NMR spin-echo and volume susceptibility measurements

Energy Technology Data Exchange (ETDEWEB)

Li, Juan.

1991-10-01

The purpose of this work is to characterize the vanadium-phosphorous oxide (V-P-O) catalysts for the selective oxidation of n-butane and 1-butene to maleic anhydride. The utility of solid state nuclear magnetic resonance as an analytical tool in this investigation lies in its sensitivity to the electronic environment surrounding the phosphorous and vanadium nuclei, and proximity of paramagnetic species. Spin-echo mapping NMR of {sup 31}p and {sup 51}v and volume magnetic susceptibility measurements were used as local microscopic probes of the presence of V{sup 5+}, V{sup 4+}, V{sup 3+} species in the model compounds: {beta}-VOPO{sub 4}, {beta}-VOPO{sub 4} treated with n-butane/1-butene, (VO){sub 2}P{sub 2}O{sub 7} treated with n-butane/1-butene; and industrial catalysts with P/V (phosphorus to vanadium) ratio of 0.9, 1.0 and 1.1, before and after treatment with n-butane and 1-butene. The NMR spectra provide a picture of how the oxidation states of vanadium are distributed in these catalysts. 73 refs., 32 figs., 8 tabs.

Vanadia-based SCR Catalysts Supported on Tungstated and Sulfated Zirconia: Influence of Doping with Potassium

DEFF Research Database (Denmark)

Due-Hansen, Johannes; Boghosian, Soghomon; Kustov, Arkadii

2007-01-01

A series of vanadium-based SCR catalysts supported on sulfated or tungstated ZrO2 were synthesized and characterized by means of N2-BET, XRD, NH3-TPD and in situ Raman spectroscopy. The effect of potassium doping on the properties of vanadia species is studied in detail. A number of catalyst...... and morphology, the surface composition and the molecular configuration of the dispersed vanadates. It was observed that poisoning with potassium had a negligible effect on the surface vanadate species (especially the V=O stretching frequency observed by in situ Raman spectroscopy) if supported on the sulfated...... the observed decrease in V=O stretching frequency and the higher proportion of dimers and higher polymers through coordination between K+ and two neighbouring V=O. The results suggest an increased resistance towards potassium doping for the vanadia-based catalysts supported on sulfated zirconia....

Hexagonal mesoporous titanosilicates as support for vanadium oxide-Promising catalysts for the oxidative dehydrogenation of n-butane

Czech Academy of Sciences Publication Activity Database

Setnička, M.; Čičmanec, P.; Bulánek, R.; Zukal, Arnošt; Pastva, Jakub

2013-01-01

Roč. 204, APR 2013 (2013), s. 132-139 ISSN 0920-5861 R&D Projects: GA ČR GAP106/10/0196 Institutional support: RVO:61388955 Keywords : mesoporous titanosilicate * hexagonal mesoporous structure * vanadium Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.309, year: 2013

Vanadium-substituted heteropolyacids immobilized on amine- functionalized mesoporous MCM-41: A recyclable catalyst for selective oxidation of alcohols with H{sub 2}O{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Dong, Xinbo [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China); Wang, Danjun [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China); College of Chemistry Chemical Engineering, Yanan University, Shaanxi Key Laboratory of Chemical Reaction Engineering, Yan' an 716000 (China); Li, Kebin [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China); Zhen, Yanzhong [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China); College of Chemistry Chemical Engineering, Yanan University, Shaanxi Key Laboratory of Chemical Reaction Engineering, Yan' an 716000 (China); Hu, Huaiming [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China); Xue, Ganglin, E-mail: xglin707@163.com [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Department of Chemistry (Ministry of Education), Northwest University, Xi' an 710069 (China)

2014-09-15

Graphical abstract: Vanadium-substituted phosphotungstic acids are immobilized on amine- functionalized mesoporous MCM-41 and the hybrid catalyst is proved to be a highly efficient solid catalyst for the oxidation of aromatic alcohols to the corresponding carbonyl compounds with H{sub 2}O{sub 2}, featured by the high conversion and selectivity, easy recovery, and quite steady reuse. - Highlights: • Vanadium-substituted phosphotungstic acid immobilized on amine-functionalized mesoporous MCM-41 are prepared. • HPAs were fixed on the inner surface of mesoporous MCM-41 by chemical bonding to aminosilane groups. • The hybrid catalyst showed much higher catalytic activity than the pure HPAs. • The hybrid catalyst is a highly efficient recyclable solid catalyst for the selective oxidation of aromatic alcohols. - Abstract: New hybrid materials of vanadium-substituted phosphotungstic acids (VHPW) immobilized on amine-functionalized mesoporous MCM-41 (VHPW/MCM-41/NH{sub 2}) are prepared and characterized by FT-IR, XRD, N{sub 2} adsorption, elemental analysis, SEM and TEM for their structural integrity and physicochemical properties. It is found that the structure of the heteropolyacids is retained upon immobilization over mesoporous materials. The catalytic activities of these hybrid materials are tested in the selective oxidation of alcohols to the carbonyl products with 30% aqueous H{sub 2}O{sub 2} as oxidant in toluene. The catalytic activities of different number of vanadium-substituted phosphotungstic acid are investigated, and among the catalysts, H{sub 5}[PV{sub 2}W{sub 10}O{sub 40}] immobilized on amine-functionalized MCM-41 exhibits the highest activity with 97% conversion and 99% selectivity in the oxidation of benzyl alcohol to benzaldehyde. The hybrid catalyst is proved to be a highly efficient recyclable solid catalyst for the selective oxidation of aromatic alcohols to the corresponding aldehydes with H{sub 2}O{sub 2}.

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.)

Vanadium

International Nuclear Information System (INIS)

Duke, V.W.A.

1983-07-01

Although a relatively abundant element, vanadium occurs only rarely in sufficient concentration to be worked commercially. In most cases, vanadium is produced as a co-product of some other element, most commonly iron. The principal ore deposits of vanadium occur in titaniferous magnetites that have been formed by magnetic segregation. Important commercial deposits of vanadium also occur associated with uranium, and with phosphate deposits. The principal uses of vanadium are in the production of special purpose, particularly high-strength low-alloy steels, in the manufacture of titanium alloys, and as a catalyst, notably in the manufacture of sulphuric acid. Small quantities of vanadium, often in combination with niobium, are added to steel to bring about toughening through grain refinement, and increased tensile strength through precipitation hardening. Known world reserves of vanadium are very large and fully adequate to meet any foreseeable demand. By far the largest known deposits of vanadium occur in South Africa. Many other similar deposits are known, but are only exploited in the USSR and China. The present total world demand for vanadium amounts to about 40 000 tons of metal annually and this is produced primarily in four countries, South Africa, the USSR, the People's Republic of China and the United States of America, in that order. South Africa is the principal vanadium producing country in the world, supplying vanadium in various forms. Vanadium has a very low and non-accumulative toxicity; recovery plants can be operated in such a manner to ensure no air or steam pollution results

Development of Vanadium Phosphaate Catalysts for Methanol Production by Selective Oxidation of Methane.

Energy Technology Data Exchange (ETDEWEB)

McCormick, R.L.

1997-10-01

This DOE sponsored study of methane partial oxidation was initiated at Amax Research and Development in Golden, CO in October of 1993. Shortly thereafter the management of Amax closed this R&D facility and the PI moved to the Colorado School of Mines. The project was begun again after contract transfer via a novation agreement. Experimental work began with testing of vandyl pyrophosphate (VPO), a well known alkane selective oxidation catalyst. It was found that VPO was not a selective catalyst for methane conversion yielding primarily CO. However, promotion of VPO with Fe, Cr, and other first row transition metals led to measurable yields for formaldehyde, as noted in the summary table. Catalyst characterization studies indicated that the role of promoters was to stabilize some of the vanadium in the V{sup 5+} oxidation state rather than the V{sup 4+} state formally expected for (VO){sub 2}P{sub 2}O{sub 7}.

Vanadium recovery process

International Nuclear Information System (INIS)

Pyrih, R.Z.; Rickard, R.S.

1978-01-01

A process for recovering vanadium values from carbonaceous type vanadium ores, and vanadium scrap, such as vanadium contaminated spent catalyst, is disclosed which comprises roasting the vanadium containing material in air at a temperature less than about 600 0 C to produce a material substantially devoid of organic matter, subjecting said roasted material to a further oxidizing roast in an oxygen atmosphere at a temperature of at least about 800 0 C for a period sufficient to convert substantially all of the vanadium to the soluble form, leaching the calcine with a suitable dilute mineral acid or water at a pH of neutral to about 2 to recover vanadium values, precipitating vanadium values as iron vanadate from the leach solution with a soluble iron compound at a pH from neutral to about 1, and recovering ferrovanadium from the iron vanadate by a reduction vacuum smelting operation. The conversion of vanadium in the ore to the soluble form by the oxidizing roast is accomplished without the addition of an alkaline salt during calcining

The selective reduction of NO@#x@# with NH@#3@# over zirconia-supported vanadia catalysts

NARCIS (Netherlands)

Szakacs, S.; Altena, G.J.; Altena, G.J.; Fransen, T.; van Ommen, J.G.; Ross, J.R.H.; Ross, J.R.H.

1993-01-01

A series of sub-monolayer vanadia-on-zirconia catalysts have been prepared and the activities of these have been measured for the selective reduction of NO with NH3. It has been found that the activity per vanadium surface species depends on the square of the vanadium surface coverage. We therefore

Metal Oxide Supported Vanadium Substituted Keggin Type Polyoxometalates as Catalyst For Oxidation of Dibenzothiophene

Science.gov (United States)

Lesbani, Aldes; Novri Meilyana, Sarah; Karim, Nofi; Hidayati, Nurlisa; Said, Muhammad; Mohadi, Risfidian; Miksusanti

2018-01-01

Supported polyoxometalatate H4[γ-H2SiV2W10O40]·nH2O with metal oxide i.e. silica, titanium, and tantalum was successfully synthesized via wet impregnation method to form H4[γ-H2SiV2W10O40]·nH2O-Si, H4[γ-H2SiV2W10O40]·nH2O-Ti, and H4[γ-H2SiV2W10O40]·nH2O-Ta. Characterization was performed using FTIR spectroscopy, X-Ray analyses, and morphology analyses using SEM. All compounds were used as the catalyst for desulfurization of dibenzothiophene (DBT). Silica and titanium supported polyoxometalate H4[γ-H2SiV2W10O40]·nH2O better than tantalum due to retaining crystallinity after impregnation process. On the other hand, compound H H4[γ-H2SiV2W10O40]·nH2O-Ta showed high catalytic activity than other supported metal oxides for desulfurization of DBT. Optimization desulfurization process resulted in 99% conversion of DBT under a mild condition at 70 °C, 0.1 g catalyst, and reaction for 3 hours. Regeneration studies showed catalyst H4[γ-H2SiV2W10O40]·nH2O-Ti was remaining catalytic activity for desulfurization of DBT.

Influence of structure of carrier (silica gel) on texture and catalytic properties of vanadium catalysts for sulfur dioxide oxidation

International Nuclear Information System (INIS)

Simonova, L.G.; Fenelonov, V.B.; Dzis'ko, V.A.; Noskova, S.P.; Kryukova, G.N.; Litvak, G.S.

1982-01-01

The influence of initial porous structure of a carrier-silica gel on texture and catalytic properties of vanadium catalysts is considered. It is shown that low thermal stability of the carrier results not only in considerable decrease of the catalyst surface during heat treatment but also in blocking part of active component in locked pores which accounts for the activity decrease in kinetic region and formation of active component forms that can not be extracted by acid

Samarium-modified vanadium phosphate catalyst for the selective oxidation of n-butane to maleic anhydride

International Nuclear Information System (INIS)

Wu, Hua-Yi; Wang, Hai-Bo; Liu, Xin-Hua; Li, Jian-Hui; Yang, Mei-Hua; Huang, Chuan-Jing; Weng, Wei-Zheng; Wan, Hui-Lin

2015-01-01

Graphical abstract: The addition of a small amount of Sm into VPO catalyst brought about great changes in its physicochemical properties such as surface area, surface morphology, phase composition and redox property, thus leading to a higher catalytic performance in the selective oxidation of n-butane to maleic anhydride, as compared to the undoped VPO catalyst. - Highlights: • The addition of Sm leads to great changes in the structure of VPO catalyst. • Sm improves performance of VPO for oxidation of n-butane to maleic anhydride. • Catalytic performance is closely related to structure of VPO catalyst. - Abstract: A series of samarium-modified vanadium phosphate catalysts were prepared and studied in selective oxidation of n-butane to maleic anhydride. The catalytic evaluation showed that Sm modification significantly increased the overall n-butane conversion and intrinsic activity. N 2 -adsorption, XRD, SEM, Raman, XPS, EPR and H 2 -TPR techniques were used to investigate the intrinsic difference among these catalysts. The results revealed that the addition of Sm to VPO catalyst can increase the surface area of the catalyst, lead to a significant change in catalyst morphology from plate-like structure into rosette-shape clusters, and largely promote the formation of (VO) 2 P 2 O 7 . All of these were related to the different catalytic performance of Sm-doped and undoped VPO catalysts. The roles of the different VOPO 4 phases and the influence of Sm were also described and discussed

Stability and catalytic performance of vanadia supported on nanostructured titania catalyst in oxidative dehydrogenation of propane

International Nuclear Information System (INIS)

Kootenaei, A.H. Shahbazi; Towfighi, J.; Khodadadi, A.; Mortazavi, Y.

2014-01-01

Highlights: • Vanadia supported on titanate nanotube shows enhanced dispersion of vanadia. • Deactivatoin during propane ODH related to the rutile development. • Titanate nanotube transfers to anatase due to calcinations and presence of vanadia. - Abstract: Titanate nanotubes with a high specific surface area were synthesized by the simple hydrothermal method and investigated as support for V 2 O 5 catalyst in oxidative dehydrogenation of propane (ODP). The structures of pristine nanotubes as well as the prepared catalysts were investigated by XRD, Raman, FTIR, HRTEM, SEM, EDS, BET, and XPS techniques. The characterization of the as-synthesized nanotubes showed the synthesis of hydrogen titanate nanotube. The incipient wetness impregnation method was utilized to prepare VTNT-x (x = 5, 10, and 15 wt.% vanadia supported on nanotube) together with VTi5 (5 wt.% vanadia supported on Degussa P25). The anatase phase was developed in VTNT-x catalysts upon calcination along with specific surface area loss. Higher vanadia loading resulted in the lowering of support capacity in maintaining vanadia in dispersed state such that eventually crystalline vanadia appeared. The measured catalyst activity demonstrates that in spite of major support surface area loss in VTNT-5 catalyst, the propylene yield is superior in comparison with VTi5 catalyst. The catalyst activity can be correlated with maximum reduction temperature. Deactivation of VTi5 and VTNT-5 as well as VTNT-15 were studied for 3,000 min time-on-stream. It was found that the activity of VTNT-5 catalyst remain unchanged while a decline in catalytic activity observed in VTi5 and VTNT-15 catalysts. The development of rutile was considered as being a major element in the deactivation of the investigated catalysts which is influenced by the presence of vanadium and reaction atmosphere

Stability and catalytic performance of vanadia supported on nanostructured titania catalyst in oxidative dehydrogenation of propane

Energy Technology Data Exchange (ETDEWEB)

Kootenaei, A.H. Shahbazi [Department of Chemical Engineering, College of Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Towfighi, J., E-mail: towfighi@modares.ac.ir [Department of Chemical Engineering, College of Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Khodadadi, A.; Mortazavi, Y. [Catalysis and Nanostructured Materials Laboratory, Oil and Gas Processing Center of Excellence, Department of Chemical Engineering, College of Engineering, University of Tehran, P.O. Box 11365-4563, Tehran (Iran, Islamic Republic of)

2014-04-01

Highlights: • Vanadia supported on titanate nanotube shows enhanced dispersion of vanadia. • Deactivatoin during propane ODH related to the rutile development. • Titanate nanotube transfers to anatase due to calcinations and presence of vanadia. - Abstract: Titanate nanotubes with a high specific surface area were synthesized by the simple hydrothermal method and investigated as support for V{sub 2}O{sub 5} catalyst in oxidative dehydrogenation of propane (ODP). The structures of pristine nanotubes as well as the prepared catalysts were investigated by XRD, Raman, FTIR, HRTEM, SEM, EDS, BET, and XPS techniques. The characterization of the as-synthesized nanotubes showed the synthesis of hydrogen titanate nanotube. The incipient wetness impregnation method was utilized to prepare VTNT-x (x = 5, 10, and 15 wt.% vanadia supported on nanotube) together with VTi5 (5 wt.% vanadia supported on Degussa P25). The anatase phase was developed in VTNT-x catalysts upon calcination along with specific surface area loss. Higher vanadia loading resulted in the lowering of support capacity in maintaining vanadia in dispersed state such that eventually crystalline vanadia appeared. The measured catalyst activity demonstrates that in spite of major support surface area loss in VTNT-5 catalyst, the propylene yield is superior in comparison with VTi5 catalyst. The catalyst activity can be correlated with maximum reduction temperature. Deactivation of VTi5 and VTNT-5 as well as VTNT-15 were studied for 3,000 min time-on-stream. It was found that the activity of VTNT-5 catalyst remain unchanged while a decline in catalytic activity observed in VTi5 and VTNT-15 catalysts. The development of rutile was considered as being a major element in the deactivation of the investigated catalysts which is influenced by the presence of vanadium and reaction atmosphere.

Structure of alumina supported vanadia catalysts for oxidative dehydrogenation of propane prepared by flame spray pyrolysis

DEFF Research Database (Denmark)

Høj, Martin; Jensen, Anker Degn; Grunwaldt, Jan-Dierk

2013-01-01

.%. The catalysts were subsequently characterized by BET surface area, X-ray diffraction (XRD), Raman, UV–vis diffuse reflectance and X-ray absorption spectroscopy (XAS) as well as measurement of the catalytic performance. The catalysts had specific surface areas from 143 to 169 m2/g corresponding to average......A series of five vanadia on alumina catalysts for oxidative dehydrogenation of propane to propene were synthesized by flame spray pyrolysis (FSP) using vanadium(III)acetylacetonate and aluminium(III)acetylacetonate dissolved in toluene as precursors. The vanadium loading was 2, 3, 5, 7.5 and 10wt...... X-ray absorption near edge structure (XANES) spectroscopy showed that the vanadia can be reduced when operating at low oxygen concentrations. The catalyst performance was determined in fixed bed reactors with an inlet gas composition of C3H8/O2/N2=5/25/70. The main products were propene, CO and CO2...

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

Structural Evolution under Reaction Conditions of Supported (NH43HPMo11VO40 Catalysts for the Selective Oxidation of Isobutane

Directory of Open Access Journals (Sweden)

Fangli Jing

2015-03-01

Full Text Available When using heteropolycompounds in the selective oxidation of isobutane to methacrolein and methacrylic acid, both the keeping of the primary structure (Keggin units and the presence of acidic sites are necessary to obtain the desired products. The structural evolution of supported (NH43HPMo11VO40 (APMV catalysts under preliminary thermal oxidizing and reducing treatments was investigated. Various techniques, such as TGA/DTG (Thermo-Gravimetric Analysis/Derivative Thermo-Gravimetry, H2-TPR (Temperature Programed Reduction, in situ XRD (X-Ray Diffraction and XPS (X-ray Photoelectron Spectroscopy, were applied. It was clearly evidenced that the thermal stability and the reducibility of the Keggin units are improved by supporting 40% APMV active phase on Cs3PMo12O40 (CPM. The partial degradation of APMV takes place depending on temperature and reaction conditions. The decomposition of ammonium cations (releasing NH3 leads to the formation of vacancies favoring cationic exchanges between vanadium coming from the active phase and cesium coming from the support. In addition, the vanadium expelled from the Keggin structure is further reduced to V4+, species, which contributes (with Mo5+ to activate isobutane. The increase in reducibility of the supported catalyst is assumed to improve the catalytic performance in comparison with those of unsupported APMV.

Uniformly active phase loaded selective catalytic reduction catalysts (V_2O_5/TNTs) with superior alkaline resistance performance

International Nuclear Information System (INIS)

Wang, Haiqiang; Wang, Penglu; Chen, Xiongbo; Wu, Zhongbiao

2017-01-01

Highlights: • VOSO_4 exhibited better synergistic effect with titanate nanotubes than NH_4VO_3. • Ion-exchange reaction occurs between VOSO_4 and titanate nanotubes. • Ion-exchange resulting in uniformly vanadium distribution on titanate nanotubes. • VOSO_4-based catalyst exhibited impressive SCR activity and alkaline resistance. - Abstract: In this work, protonated titanate nanotubes was performed as a potential useful support and different vanadium precursors (NH_4VO_3 and VOSO_4) were used to synthesize deNO_x catalysts. The results showed that VOSO_4 exhibited better synergistic effect with titanate nanotubes than NH_4VO_3, which was caused by the ion-exchange reaction. Then high loading content of vanadium, uniformly active phase distribution, better dispersion of vanadium, more acid sites, better V"5"+/V"4"+ redox cycles and superior oxygen mobility were achieved. Besides, VOSO_4-based titanate nanotubes catalysts also showed enhanced alkaline resistance than particles (P25) based catalysts. It was strongly associated with its abundant acid sites, large surface area, flexible redox cycles and oxygen transfer ability. For the loading on protonated titanate nanotubes, active metal with cation groups was better precursors than anion ones. V_2O_5/TNTs catalyst was a promising substitute for the commercial vanadium catalysts and the work conducted herein provided a useful idea to design uniformly active phase loaded catalyst.

Formaldehyde formation in coupled oxidation of methane and methanol over V2O5 and MoO3 silica supported catalysts

International Nuclear Information System (INIS)

Lojewska, J.; Makowski, W.; Fajardo Farre, A.; Dziembaj, R.

2003-01-01

The effect of methanol on partial oxidation of methane has been studied on standard molybdena and vanadia catalysts supported on silica. Prior to catalytic tests the catalysts were characterized by BET, SEM/EDAX and TPR/O methods. Three types of catalytic tests were performed giving temperature and contact time dependence on the catalyst activity and selectivity: partial oxidations of methane, methanol and methane/methanol mixtures. The methanol showed an activating impact on the partial oxidation of methane over all used catalysts samples, but the strongest one over Mo 3 /SiO 2 . In the absence of CH 3 OH the only catalyst, which exhibited HCHO selectivity, was low loaded vanadia catalyst. It has been put forward that methanol may enhance formation of oxygen active species, prerequisites for activating methane molecules, through reducing vanadia cations and causing breakage of vanadium oxygen bonds. (author)

Butanol Dehydration over V₂O₅-TiO₂/MCM-41 Catalysts Prepared via Liquid Phase Atomic Layer Deposition.

Science.gov (United States)

Choi, Hyeonhee; Bae, Jung-Hyun; Kim, Do Heui; Park, Young-Kwon; Jeon, Jong-Ki

2013-04-29

MCM-41 was used as a support and, by using atomic layer deposition (ALD) in the liquid phase, a catalyst was prepared by consecutively loading titanium oxide and vanadium oxide to the support. This research analyzes the effect of the loading amount of vanadium oxide on the acidic characteristics and catalytic performance in the dehydration of butanol. The physical and chemical characteristics of the TiO₂-V₂O₅/MCM-41 catalysts were analyzed using XRF, BET, NH₃-TPD, XRD, Py-IR, and XPS. The dehydration reaction of butanol was performed in a fixed bed reactor. For the samples with vanadium oxide loaded to TiO₂/MCM-41 sample using the liquid phase ALD method, it was possible to increase the loading amount until the amount of vanadium oxide reached 12.1 wt %. It was confirmed that the structural properties of the mesoporous silica were retained well after titanium oxide and vanadium loading. The NH₃-TPD and Py-IR results indicated that weak acid sites were produced over the TiO₂/MCM-41 samples, which is attributed to the generation of Lewis acid sites. The highest activity of the V₂O₅(12.1)-TiO₂/MCM-41 catalyst in 2-butanol dehydration is ascribed to it having the highest number of Lewis acid sites, as well as the highest vanadium dispersion.

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

-earth exchanged Y zeolite in a silica-alumina matrix. X-ray fluorescence analyses showed that the rare earths used in preparing the catalysts were a mixture of lanthanum and cerium. Antimony found in the spent catalyst was added during operation of the FCC unit as a way to suppress the adverse effects of deposited nickel. The fresh HDS samples consisted of sulfided nickel and molybdenum on an alumina support. The spent catalyst showed nearly 10% vanadium on the catalyst and a modest increase in nickel and sulfur on the catalyst as a result of operations. Hydrocracking catalysts were not available for this study.

Effect of vanadium contamination on the framework and micropore structure of ultra stable Y-zeolite.

Science.gov (United States)

Etim, U J; Xu, B; Ullah, Rooh; Yan, Z

2016-02-01

Y-zeolites are the main component of fluid catalytic cracking (FCC) catalyst for conversion of crude petroleum to products of high demand including transportation fuel. We investigated effects of vanadium which is present as one of the impurities in FCC feedstock on the framework and micropore structure of ultra-stable (US) Y-zeolite. The zeolite samples were prepared and characterized using standard techniques including: (1) X-ray diffraction, (2) N2 adsorption employing non local density functional theory method, NLDFT, (3) Transmittance and Pyridine FTIR, (4) Transmittance electron microscopy (TEM), and (5) (27)Al and (29)Si MAS-NMR. Results revealed that in the presence of steam, vanadium caused excessive evolution of non inter-crystalline mesopores and structural damage. The evolved mesopore size averaged about 25.0nm at 0.5wt.% vanadium loading, far larger than mesopore size in zeolitic materials with improved hydrothermal stability and performance for FCC catalyst. A mechanism of mesopore formation based on accelerated dealumination has been proposed and discussed. Vanadium immobilization experiments conducted to mitigate vanadium migration into the framework clearly showed vanadium is mobile at reaction conditions. From the results, interaction of vanadium with the passivator limits and decreases mobility and activity of vanadium into inner cavities of the zeolite capable of causing huge structure breakdown and acid sites destruction. This study therefore deepens insight into the causes of alteration in activity and selectivity of vanadium contaminated catalyst and hints on a possible mechanism of passivation in vanadium passivated FCC catalyst. Copyright © 2015 Elsevier Inc. All rights reserved.

Hydrous titanium oxide-supported catalysts

International Nuclear Information System (INIS)

Dosch, R.G.; Stohl, F.V.; Richardson, J.T.

1990-01-01

Catalysts were prepared on hydrous titanium oxide (HTO) supports by ion exchange of an active metal for Na + ions incorporated in the HTO support during preparation by reaction with the parent Ti alkoxide. Strong active metal-HTO interactions as a result of the ion exchange reaction can require significantly different conditions for activation as compared to catalysts prepared by more widely used incipient wetness methods. The latter catalysts typically involve conversion or while the HTO catalysts require the alteration of electrostatic bonds between the metal and support with subsequent alteration of the support itself. In this paper, the authors discuss the activation, via sulfidation or reduction, of catalysts consisting of Co, Mo, or Ni-Mo dispersed on HTO supports by ion exchange. Correlations between the activation process and the hydrogenation, hydrodeoxygenation, and hydrodesulfurization activities of the catalysts are presented

Advances in propane ammoxidation catalyst technology

Energy Technology Data Exchange (ETDEWEB)

Prada Silvy, R.; Grange, P. [Unite de Catalyse et Chimie des Materiaux Divises, Univ. Cathologique de Louvain, Louvain-la-Neuve (Belgium)

2003-09-01

Comparison of the catalytic performance of different propane ammoxidation catalyst systems from the patent literature is established in order to identify the most promising formulation towards process commercialization scale. Vanadium aluminum oxynitride material shows the highest acrylonitrile production level per hour and per amount of catalyst with respect to conventional vanadium-molybdate and vanadium- antimonate mixed oxide propane ammoxidation systems. Acrylonitrile, hydrogen cyanide and acetonitrile production from propane ammoxidation is the key factor for obtaining competitive advantages over current propylene technology. (orig.)

Alternative alkali resistant deNOx catalysts

DEFF Research Database (Denmark)

Putluru, Siva Sankar Reddy; Kristensen, Steffen Buus; Due-Hansen, Johannes

2012-01-01

by onepot sol–gel method. All catalysts were characterized by BET, XRPD and NH3-TPD. Initial SCR activities of 8 out of 9 catalysts showed higher NO conversion at least at one temperature in the temperature range 300–500 ◦C compared to the conventional V2O5-WO3/TiO2 catalyst. After potassium poisoning (100......Alternative alkali resistant deNOx catalysts were prepared using three different supports ZrO2, TiO2 and Mordenite zeolite. The majority of the catalysts were prepared by incipient wetness impregnation of a commercial support, with vanadium, copper or iron precursor, one catalyst was prepared......–130 µmol of K/g of catalyst) the relative drop in SCR activity and acidity was lower for all the alternative catalysts compared to the industrial V2O5-WO3/TiO2 catalyst. Furthermore, Cu/MOR and Nano-V2O5/Sul-TiO2 catalysts showed 8–16 times higher SCR activities than the conventional even after high...

Additive for vanadium and sulfur oxide capture in catalytic cracking

International Nuclear Information System (INIS)

Chin, A.A.; Sapre, A.V.; Sarli, M.S.

1991-01-01

This patent describes a fluid catalytic cracking process in which a hydrocarbon feedstock. It comprises: a vanadium contaminant in an amount of a least 2 ppmw is cracked under fluid catalytic cracking conditions with a solid, particulate cracking catalyst to produce cracking products of lower molecular weight while depositing carbonaceous material on the particles of cracking catalyst, separating the particles of cracking catalyst from the cracking products in the disengaging zone and oxidatively regenerating the cracking catalyst by burning off the deposited carbonaceous material in a regeneration zone, the improvement comprising reducing the make-up rate of the cracking catalyst by contacting the cracking feed with a particulate additive composition for passivating the vanadium content of the feed, comprising an alkaline earth metal oxide and an alkaline earth metal spinel

Biodiesel production over copper vanadium phosphate

International Nuclear Information System (INIS)

Chen, Lei; Yin, Ping; Liu, Xiguang; Yang, Lixia; Yu, Zhongxi; Guo, Xin; Xin, Xinquan

2011-01-01

In the present study, copper vanadium phosphate (CuVOP) with three-dimensional network structure was synthesized by hydrothermal method, and was characterized by Infrared spectrum (IR), elemental analysis (EA), EDXRF (energy dispersive X ray fluorescence) etc. Moreover, soybean oil was used as feedstock for producing biodiesel, and biodiesel was produced by CuVOP-catalyzed transesterification process. Response surface methodology was employed to statistically evaluate and optimize the conditions for the maximum conversion to biodiesel, and the effects of amount of catalyst, ratio of methanol to oil, reaction time and reaction temperature were investigated by the 2 4 full-factorial central composite design. The maximum conversion is obtained at amount of catalyst of 1.5%, methanol/oil molar ratio of 6.75, reaction temperature of 65 o C and reaction time of 5 h. Copper vanadium phosphate CuVOP resulted very active in the transesterification reaction for biodiesel production. -- Research highlights: → Copper vanadium phosphate CuVOP with three-dimensional network structure was prepared successfully. Moreover, for the transesterification reaction of soybean oil with methanol under atmospheric pressure, CuVOP had higher catalytic activity and the effects of production conditions such as amount of catalysts etc. were analyzed by response surface methodology.

Uniformly active phase loaded selective catalytic reduction catalysts (V{sub 2}O{sub 5}/TNTs) with superior alkaline resistance performance

Energy Technology Data Exchange (ETDEWEB)

Wang, Haiqiang; Wang, Penglu [Key Laboratory of Environment Remediation and Ecological Health, Ministry of Education, College of Environmental & Resources Science, Zhejiang University, 310058 Hangzhou (China); Zhejiang Provincial Engineering Research Center of Industrial Boiler & Furnace Flue Gas Pollution Control, Hangzhou 310027 (China); Chen, Xiongbo [South China Institute of Environmental Sciences, Ministry of Environmental Protection, Guangzhou 510655 (China); Wu, Zhongbiao, E-mail: zbwu@zju.edu.cn [Key Laboratory of Environment Remediation and Ecological Health, Ministry of Education, College of Environmental & Resources Science, Zhejiang University, 310058 Hangzhou (China); Zhejiang Provincial Engineering Research Center of Industrial Boiler & Furnace Flue Gas Pollution Control, Hangzhou 310027 (China)

2017-02-15

Highlights: • VOSO{sub 4} exhibited better synergistic effect with titanate nanotubes than NH{sub 4}VO{sub 3}. • Ion-exchange reaction occurs between VOSO{sub 4} and titanate nanotubes. • Ion-exchange resulting in uniformly vanadium distribution on titanate nanotubes. • VOSO{sub 4}-based catalyst exhibited impressive SCR activity and alkaline resistance. - Abstract: In this work, protonated titanate nanotubes was performed as a potential useful support and different vanadium precursors (NH{sub 4}VO{sub 3} and VOSO{sub 4}) were used to synthesize deNO{sub x} catalysts. The results showed that VOSO{sub 4} exhibited better synergistic effect with titanate nanotubes than NH{sub 4}VO{sub 3}, which was caused by the ion-exchange reaction. Then high loading content of vanadium, uniformly active phase distribution, better dispersion of vanadium, more acid sites, better V{sup 5+}/V{sup 4+} redox cycles and superior oxygen mobility were achieved. Besides, VOSO{sub 4}-based titanate nanotubes catalysts also showed enhanced alkaline resistance than particles (P25) based catalysts. It was strongly associated with its abundant acid sites, large surface area, flexible redox cycles and oxygen transfer ability. For the loading on protonated titanate nanotubes, active metal with cation groups was better precursors than anion ones. V{sub 2}O{sub 5}/TNTs catalyst was a promising substitute for the commercial vanadium catalysts and the work conducted herein provided a useful idea to design uniformly active phase loaded catalyst.

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

Energy Technology Data Exchange (ETDEWEB)

Barton, Thomas; Argyle, Morris; Popa, Tiberiu

2009-06-30

This project is in response to a requirement for a system that combines water gas shift technology with separation technology for coal derived synthesis gas. The justification of such a system would be improved efficiency for the overall hydrogen production. By removing hydrogen from the synthesis gas stream, the water gas shift equilibrium would force more carbon monoxide to carbon dioxide and maximize the total hydrogen produced. Additional benefit would derive from the reduction in capital cost of plant by the removal of one step in the process by integrating water gas shift with the membrane separation device. The answer turns out to be that the integration of hydrogen separation and water gas shift catalysis is possible and desirable. There are no significant roadblocks to that combination of technologies. The problem becomes one of design and selection of materials to optimize, or at least maximize performance of the two integrated steps. A goal of the project was to investigate the effects of alloying elements on the performance of vanadium membranes with respect to hydrogen flux and fabricability. Vanadium was chosen as a compromise between performance and cost. It is clear that the vanadium alloys for this application can be produced, but the approach is not simple and the results inconsistent. For any future contracts, large single batches of alloy would be obtained and rolled with larger facilities to produce the most consistent thin foils possible. Brazing was identified as a very likely choice for sealing the membranes to structural components. As alloying was beneficial to hydrogen transport, it became important to identify where those alloying elements might be detrimental to brazing. Cataloging positive and negative alloying effects was a significant portion of the initial project work on vanadium alloying. A water gas shift catalyst with ceramic like structural characteristics was the second large goal of the project. Alumina was added as a

Selective nano alumina supported vanadium oxide catalysts for oxidative dehydrogenation of ethylbenzene to styrene using CO2 as soft oxidant

Directory of Open Access Journals (Sweden)

A.M. Elfadly

2013-12-01

Full Text Available Nano alumina-supported V2O5 catalysts with different loadings have been tested for the dehydrogenation of ethylbenzene with CO2 as an oxidant. High surface area nano-alumina was prepared and used as support for V2O5 as the catalyst. The catalysts were synthesized by impregnation techniques followed by calcinations and microwave treatment, denoted as V2O5/γ-Al2O3-C and V2O5/γ-Al2O3-MW, respectively. The V2O5 loading was varied on nano-alumina from 5 to 30 wt%. The support and catalysts were characterized by X-ray diffraction (XRD, Barett–Joyner–Halenda (BJH pore-size distribution, N2-adsorption isotherms, Fourier transform infrared (FT-IR, scanning electron microscopy (SEM, transmission electron microscopy (TEM and temperature programed desorption (TPD-NH3. The characterization results indicated that V2O5 is highly dispersed on alumina up to 30%-V2O5/γ-Al2O3-MW prepared by MW method. The TPD studies indicated that there are significant differences in acid amount and strength for V2O5/γ-Al2O3-C and V2O5/γ-Al2O3-MW-catalysts. The catalytic activity of the prepared catalysts was evaluated in the temperature range 450–600 °C in relation to the physicochemical properties and surface acidity. The results revealed that optimum catalytic activity and selectivity (∼100% toward styrene production were obtained using 10% V2O5/γ-Al2O3-MW catalyst treated with microwave.

Recovery by solvent extraction of vanadium from spent catalysts leaching solutions using Primene 81R

Directory of Open Access Journals (Sweden)

Lozano, L. J.

2001-10-01

Full Text Available Recovery of vanadium contained in solutions coming from spent catalysts leaching process by means of solvent extraction techniques using primary amine Primene 81R, has been studied in this work, resulting in an industrial multistage process for the treatment of these effluents. Results obtained allows to propose an extraction mechanism for vanadium(V with this amine in acidic media, verifying the great influence of pH on the process and fix adequate ranges for variables: O/A ratio, organic phase composition, pH, stirring speed and phase separation speed. These values were simulated in industrial conditions. Vanadium is finally recovered by means of precipitation as ammonium metavanadate and later calcination to obtain vanadium pentoxide of commercial grade.

En el presente trabajo se ha estudiado la recuperación del vanadio contenido en soluciones procedentes del proceso de lixiviación de catalizadores agotados, por medio de la técnica de extracción con disolventes, empleando la amina primaria PRIMENE 81R, planteando un proceso industrial multietapa para el tratamiento de estos efluentes. Los resultados obtenidos permiten proponer un mecanismo de extracción para el vanadio(V, con esta amina en medio ácido, verificando la gran influencia del pH en el proceso y Ajando los rangos adecuados para las siguientes variables: relación O/A, composición de la fase orgánica, pH, velocidad de agitación y velocidad de separación de fases. Esos valores se simularon en condiciones industriales. El vanadio se recupera finalmente precipitándolo como metavanadato amónico y posterior calcinación para obtener pentóxido de vanadio de calidad comercial.

Highly Efficient Gas-Phase Oxidation of Renewable Furfural to Maleic Anhydride over Plate Vanadium Phosphorus Oxide Catalyst.

Science.gov (United States)

Li, Xiukai; Ko, Jogie; Zhang, Yugen

2018-02-09

Maleic anhydride (MAnh) and its acids are critical intermediates in chemical industry. The synthesis of maleic anhydride from renewable furfural is one of the most sought after processes in the field of sustainable chemistry. In this study, a plate vanadium phosphorus oxide (VPO) catalyst synthesized by a hydrothermal method with glucose as a green reducing agent catalyzes furfural oxidation to MAnh in the gas phase. The plate catalyst-denoted as VPO HT -has a preferentially exposed (200) crystal plane and exhibited dramatically enhanced activity, selectivity and stability as compared to conventional VPO catalysts and other state-of-the-art catalytic systems. At 360 °C reaction temperature with air as an oxidant, about 90 % yield of MAnh was obtained at 10 vol % of furfural in the feed, a furfural concentration value that is much higher than those (<2 vol %) reported for other catalytic systems. The catalyst showed good long-term stability and there was no decrease in activity or selectivity for MAnh during the time-on-stream of 25 h. The high efficiency and catalyst stability indicate the great potential of this system for the synthesis of maleic anhydride from renewable furfural. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pepspectives of chlorine application in metallurgy of vanadium

International Nuclear Information System (INIS)

Korshunov, B.G.; Kutsenko, S.A.

1983-01-01

The most expedient variants of reprocessing of vanadium technical oxide (5), ferrovanadium and converter slags by chlorine technology with production of pure metal are considered. It is shown that production of vanadium by the way of electro- or metallothermal reduction of chlorides provides more plastic metal in comparison with reduction from oxides. The methods of production of VOCl 3 , VCl 4 and vanadium lowest chlorides are considered. Necessity of expansion of production of vanadium chlorine derivatives is dictated as well by their increasing application in different areas of national economy, in particular, as catalysts in organic synthesis

Vanadium

Science.gov (United States)

Kelley, Karen D.; Scott, Clinton T.; Polyak, Désirée E.; Kimball, Bryn E.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

2017-12-19

Vanadium is used primarily in the production of steel alloys; as a catalyst for the chemical industry; in the making of ceramics, glasses, and pigments; and in vanadium redox-flow batteries (VRBs) for large-scale storage of electricity. World vanadium resources in 2012 were estimated to be 63 million metric tons, which include about 14 million metric tons of reserves. The majority of the vanadium produced in 2012 was from China, Russia, and South Africa.Vanadium is extracted from several different types of mineral deposits and from fossil fuels. These deposits include vanadiferous titanomagnetite (VTM) deposits, sandstone-hosted vanadium (with or without uranium) deposits (SSV deposits), and vanadium-rich black shales. VTM deposits are the principal source of vanadium and consist of magmatic accumulations of ilmenite and magnetite containing 0.2 to 1 weight percent vanadium pentoxide (V2O5). SSV deposits are another important source; these deposits have average ore grades that range from 0.1 to greater than 1 weight percent V2O5. The United States has been and is currently the main producer of vanadium from SSV deposits, particularly those on the Colorado Plateau. Vanadium-rich black shales occur in marine successions that were deposited in epeiric (inland) seas and on continental margins. Concentrations in these shales regularly exceed 0.18 weight percent V2O5 and can be as high as 1.7 weight percent V2O5. Small amounts of vanadium have been produced from the Alum Shale in Sweden and from ferrophosphorus slag generated during the reduction of phosphate to elemental phosphorus in ore from shales of the Phosphoria Formation in Idaho and Wyoming. Because vanadium enrichment occurs in beds that are typically only a few meters thick, most of the vanadiferous black shales are not currently economic, although they may become an important resource in the future. Significant amounts of vanadium are recovered as byproducts of petroleum refining, and processing of coal, tar

De-oxygenation of CO2 by using Hydrogen, Carbon and Methane over Alumina-Supported Catalysts

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R.Y. Raskar

2012-06-01

Full Text Available The de-oxygenation of CO2 was explored by using hydrogen, methane, carbon etc., over alumina supported catalysts. The alumina-supported ruthenium, rhodium, platinum, molybdenum, vanadium and magnesium catalysts were first reduced in hydrogen atmosphere and then used for the de-oxygenation of CO2. Furthermore, experimental variables for the de-oxygenation of CO2 were temperature (range 50 to 650 oC, H2/CO2 mole ratios (1.0 to 5, and catalyst loading (0.5 to 10 wt %. During the de-oxygenation of CO2 with H2 or CH4 or carbon, conversion of CO2, selectivity to CO and CH4 were estimated. Moreover, 25.4 % conversion of CO2 by hydrogen was observed over 1 wt% Pt/Al2O3 catalyst at 650 oC with 33.8 % selectivity to CH4. However, 8.1 to 13.9 % conversion of CO2 was observed over 1 wt% Pt/Al2O3 catalyst at 550 oC in the presence of both H2 and CH4. Moreover, 42.8 to 79.4 % CH4 was converted with 9 to 23.1 % selectivity to CO. It was observed that the de-oxygenation of CO2 by hydrogen, carbon and methane produced carbon, CO and CH4. © 2012 BCREC UNDIP. All rights reservedReceived: 6th February 2012; Revised: 23rd April 2012; Accepted: 24th April 2012[How to Cite: R. Y. Raskar, K. B. Kale, A. G. Gaikwad. (2011. De-oxygenation of CO2 by using Hydrogen, Carbon and Methane over Alumina-Supported Catalysts. Bulletin of Chemical Reaction Engineering & Catalysis, 7 (1: 59-69.  doi:10.9767/bcrec.7.1.1631.59-69][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.7.1.1631.59-69 ] | View in 

Impeded solid state reactions and transformations in ceramic catalysts supports and catalysts

Directory of Open Access Journals (Sweden)

Ernő E. Kiss

2012-12-01

Full Text Available Impeded chemical reactions and impeded polymorphous transformation in materials are discussed, as desired effects, for stabilization of ceramic catalyst supports and ceramic based catalysts. This paper gives a short overview about the possibilities of slowing down the aging processes in ceramic catalyst supports and catalysts. Special attention is given to alumina and titania based catalysts.

An improved method of preparation of nanoparticular metal oxide catalysts

DEFF Research Database (Denmark)

2014-01-01

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

Carbons and carbon supported catalysts in hydroprocessing

Energy Technology Data Exchange (ETDEWEB)

Furimsky, Edward

2009-07-01

This book is a comprehensive summary of recent research in the field and covers all areas of carbons and carbon materials. The potential application of carbon supports, particularly those of carbon black (CB) and activated carbon (AC) in hydroprocessing catalysis are covered. Novel carbon materials such as carbon fibers and carbon nano tubes (CNT) are also covered, including the more recent developments in the use of fullerenes in hydroprocessing applications. Although the primary focus of this book is on carbons and carbon supported catalysts, it also identifies the difference in the effect of carbon supports compared with the oxidic supports, particularly that of the Al{sub 2}O{sub 3}. The difference in catalyst activity and stability was estimated using both model compounds and real feeds under variable conditions. The conditions applied during the preparation of carbon supported catalysts are also comprehensively covered and include various methods of pretreatment of carbon supports to enhance catalyst performance. The model compounds results consistently show higher hydrodesulfurization and hydrodeoxygenation activities of carbon supported catalysts than that of the Al{sub 2}O{sub 3} supported catalysts. Also, the deactivation of the former catalysts by coke deposition was much less evident. Chapter 6.3.1.3 is on carbon-supported catalysts: coal-derived liquids.

Determination of vanadium (4) and (5) in the presence of both

International Nuclear Information System (INIS)

Malyuta, V.F.; Solomatin, V.T.; Berezhnoj, A.I.

1983-01-01

A study was made on the possibility of vanadium (4) and (5) determination in the presence of both by titration with ferrocene in aqueous solutions. 5-6 M H 2 SO 4 is the optimal medium for vanadium (5) titration. Vanadium (4) is titrated in the mixture of 2-2.5 M H 2 SO 4 and 8-10 M H 3 PO 4 . The method for vanadium (4) and (5) determination in vanadium catalysts was developed. Vanadium (5) is titrated amperometrically or potentiometrically by propanol solution of ferrocence in H 2 SO 4 . Concentrated H 3 PO 4 is added and the summary vanadium (4) is titrated. The relative standard deviations for 0.04-2% vanadium (4) content and 0.3-4% vanadium (5) content equal 0.06-0.03 and 0.05-0.02, respectively

Alumina- and titania-based monolithic catalysts for low temperature selective catalytic reduction of nitrogen oxides

International Nuclear Information System (INIS)

Blanco, J.; Avila, P.; Suarez, S.; Martin, J.A.; Knapp, C.

2000-01-01

The selective catalytic reduction of NO+NO 2 (NO x ) at low temperature (180-230C) with ammonia has been investigated with copper-nickel and vanadium oxides supported on titania and alumina monoliths. The influence of the operating temperature, as well as NH 3 /NO x and NO/NO 2 inlet ratios has been studied. High NO x conversions were obtained at operating conditions similar to those used in industrial scale units with all the catalysts. Reaction temperature, ammonia and nitrogen dioxide inlet concentration increased the N 2 O formation with the copper-nickel catalysts, while no increase was observed with the vanadium catalysts. The vanadium-titania catalyst exhibited the highest DeNO x activity, with no detectable ammonia slip and a low N 2 O formation when NH 3 /NO x inlet ratio was kept below 0.8. TPR results of this catalyst with NO/NH 3 /O 2 , NO 2 /NH 3 /O 2 and NO/NO 2 /NH 3 /O 2 feed mixtures indicated that the presence of NO 2 as the only nitrogen oxide increases the quantity of adsorbed species, which seem to be responsible for N 2 O formation. When NO was also present, N 2 O formation was not observed

Oxidation catalysts on alkaline earth supports

Science.gov (United States)

Mohajeri, Nahid

2017-03-21

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

Hydrothermal performance of catalyst supports

Energy Technology Data Exchange (ETDEWEB)

Elam, Jeffrey W.; Marshall, Christopher L.; Libera, Joseph A.; Dumesic, James A.; Pagan-Torres, Yomaira J.

2018-04-10

A high surface area catalyst with a mesoporous support structure and a thin conformal coating over the surface of the support structure. The high surface area catalyst support is adapted for carrying out a reaction in a reaction environment where the thin conformal coating protects the support structure within the reaction environment. In various embodiments, the support structure is a mesoporous silica catalytic support and the thin conformal coating comprises a layer of metal oxide resistant to the reaction environment which may be a hydrothermal environment.

The black rock series supported SCR catalyst for NO x removal.

Science.gov (United States)

Xie, Bin; Luo, Hang; Tang, Qing; Du, Jun; Liu, Zuohua; Tao, Changyuan

2017-09-01

Black rock series (BRS) is of great potential for their plenty of valued oxides which include vanadium, iron, alumina and silica oxides, etc. BRS was used for directly preparing of selective catalytic reduction (SCR) catalyst by modifying its surface texture with SiO 2 -TiO 2 sols and regulating its catalytic active constituents with V 2 O 5 and MoO 3 . Consequently, 90% NO removal ratio was obtained within 300-400 °C over the BRS-based catalyst. The structure and properties of the BRS-based catalyst were characterized by the techniques of N 2 adsorption-desorption, X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), H 2 -temperature programmed reduction (H 2 -TPR), and NH 3 -temperature programmed desorption (NH 3 -TPD). The results revealed that the BRS-based catalyst possesses favorable properties for NO x removal, including highly dispersed active components, abundant surface-adsorbed oxygen O α , well redox property, and numerous Brønsted acid sites. Particularly, the BRS-based catalyst exhibited considerable anti-poisoning performance compared with commercial TiO 2 -based catalyst. The former catalyst shows a NO conversion surpassing 80% from 300 to 400 °C for potassium poisoning, and a durability of SO 2 and H 2 O exceeding 85% at temperatures from 300 to 450 °C.

Synergistic effect of carbon nanofiber/nanotube composite catalyst on carbon felt electrode for high-performance all-vanadium redox flow battery.

Science.gov (United States)

Park, Minjoon; Jung, Yang-jae; Kim, Jungyun; Lee, Ho il; Cho, Jeaphil

2013-10-09

Carbon nanofiber/nanotube (CNF/CNT) composite catalysts grown on carbon felt (CF), prepared from a simple way involving the thermal decomposition of acetylene gas over Ni catalysts, are studied as electrode materials in a vanadium redox flow battery. The electrode with the composite catalyst prepared at 700 °C (denoted as CNF/CNT-700) demonstrates the best electrocatalytic properties toward the V(2+)/V(3+) and VO(2+)/VO2(+) redox couples among the samples prepared at 500, 600, 700, and 800 °C. Moreover, this composite electrode in the full cell exhibits substantially improved discharge capacity and energy efficiency by ~64% and by ~25% at 40 mA·cm(-2) and 100 mA·cm(-2), respectively, compared to untreated CF electrode. This outstanding performance is due to the enhanced surface defect sites of exposed edge plane in CNF and a fast electron transfer rate of in-plane side wall of the CNT.

Metal recovery from spent refinery catalysts by means of biotechnological strategies

International Nuclear Information System (INIS)

Beolchini, F.; Fonti, V.; Ferella, F.; Veglio, F.

2010-01-01

A bioleaching study aimed at recovering metals from hazardous spent hydroprocessing catalysts was carried out. The exhaust catalyst was rich in nickel (4.5 mg/g), vanadium (9.4 mg/g) and molybdenum (4.4 mg/g). Involved microorganisms were iron/sulphur oxidizing bacteria. Investigated factors were elemental sulphur addition, ferrous iron addition and actions contrasting a possible metal toxicity (either adding powdered activated charcoal or simulating a cross current process by means of periodical filtration). Ferrous iron resulted to be essential for metal extraction: nickel and vanadium extraction yields were 83% and 90%, respectively, while about 50% with no iron. The observed values for molybdenum extraction yields were not as high as Ni and V ones (the highest values were around 30-40%). The investigated actions aimed at contrasting a possible metal toxicity resulted not to be effective; in contrast, sequential filtration of the liquor leach had a significant negative effect on metals extraction. Nickel and vanadium dissolution kinetics resulted to be significantly faster than molybdenum dissolution ones. Furthermore, a simple first order kinetic model was successfully fitted to experimental data. All the observed results supported the important role of the indirect mechanism in bioleaching of LC-Finer catalysts.

Metal recovery from spent refinery catalysts by means of biotechnological strategies

Energy Technology Data Exchange (ETDEWEB)

Beolchini, F., E-mail: f.beolchini@univpm.it [Department of Marine Sciences, Polytechnic University of Marche, Via Brecce Bianche, 60131 Ancona (Italy); Fonti, V. [Department of Marine Sciences, Polytechnic University of Marche, Via Brecce Bianche, 60131 Ancona (Italy); Ferella, F.; Veglio, F. [Department of Chemistry, Chemical Engineering and Materials, University of L' Aquila, Monteluco di Roio, 67040 L' Aquila (Italy)

2010-06-15

A bioleaching study aimed at recovering metals from hazardous spent hydroprocessing catalysts was carried out. The exhaust catalyst was rich in nickel (4.5 mg/g), vanadium (9.4 mg/g) and molybdenum (4.4 mg/g). Involved microorganisms were iron/sulphur oxidizing bacteria. Investigated factors were elemental sulphur addition, ferrous iron addition and actions contrasting a possible metal toxicity (either adding powdered activated charcoal or simulating a cross current process by means of periodical filtration). Ferrous iron resulted to be essential for metal extraction: nickel and vanadium extraction yields were 83% and 90%, respectively, while about 50% with no iron. The observed values for molybdenum extraction yields were not as high as Ni and V ones (the highest values were around 30-40%). The investigated actions aimed at contrasting a possible metal toxicity resulted not to be effective; in contrast, sequential filtration of the liquor leach had a significant negative effect on metals extraction. Nickel and vanadium dissolution kinetics resulted to be significantly faster than molybdenum dissolution ones. Furthermore, a simple first order kinetic model was successfully fitted to experimental data. All the observed results supported the important role of the indirect mechanism in bioleaching of LC-Finer catalysts.

Catalyst for hydrocarbon conversion

International Nuclear Information System (INIS)

Duhaut, P.; Miquel, J.

1975-01-01

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

In-situ hydrodeoxygenation of phenol by supported Ni catalyst-explanation for catalyst performance

DEFF Research Database (Denmark)

Wang, Ze; Zeng, Ying; Lin, Weigang

2017-01-01

In-situ hydrodeoxygenation of phenol with aqueous hydrogen donor over supported Ni catalyst was investigated. The supported Ni catalysts exerted very poor performance, if formic acid was used as the hydrogen donor. Catalyst modification by loading K, Na, Mg or La salt could not make the catalyst...... performance improved. If gaseous hydrogen was used as the hydrogen source the activity of Ni/Al2O3 was pretty high. CO2 was found poisonous to the catalysis, due to the competitive adoption of phenol with CO2. If formic acid was replaced by methanol, the catalyst performance improved remarkably, with major...... products of cyclohexanone and cyclohexanol. The better effect of methanol enlightened the application of the supported Ni catalyst in in-situ hydrodeoxygenation of phenol....

Chloride supporting electrolytes for all-vanadium redox flow batteries.

Science.gov (United States)

Kim, Soowhan; Vijayakumar, M; Wang, Wei; Zhang, Jianlu; Chen, Baowei; Nie, Zimin; Chen, Feng; Hu, Jianzhi; Li, Liyu; Yang, Zhenguo

2011-10-28

This paper examines vanadium chloride solutions as electrolytes for an all-vanadium redox flow battery. The chloride solutions were capable of dissolving more than 2.3 M vanadium at varied valence states and remained stable at 0-50 °C. The improved stability appeared due to the formation of a vanadium dinuclear [V(2)O(3)·4H(2)O](4+) or a dinuclear-chloro complex [V(2)O(3)Cl·3H(2)O](3+) in the solutions over a wide temperature range. The all-vanadium redox flow batteries with the chloride electrolytes demonstrated excellent reversibility and fairly high efficiencies. Only negligible, if any, gas evolution was observed. The improved energy capacity and good performance, along with the ease in heat management, would lead to substantial reduction in capital cost and life-cycle cost, making the vanadium chloride redox flow battery a promising candidate for stationary applications. This journal is © the Owner Societies 2011

Iron carbide on titania surface modified with group VA oxides as Fischer-Tropsch catalysts

International Nuclear Information System (INIS)

Wachs, I.E.; Fiato, R.A.; Chersich, C.C.

1986-01-01

A catalyst is described comprising iron carbide supported on a surface modified titania wherein the support comprises an oxide of a metal selected form the group consisting of niobium, vanadium, tantalum or mixture thereof supported on the titania wherein at least a portion of the supported oxide of niobium, vanandium, tantalum or mixture is in a non-crystalline form. The amount of the supported oxide ranges from about 0.5 to 25 weight percent metal oxide on the titania support based on the total support composition and the catalyst contains at least about 2 milligrams of iron, calculated as Fe/sub 2/O/sub 3/, per square meter of support surface

Supported catalyst systems and method of making biodiesel products using such catalysts

Science.gov (United States)

Kim, Manhoe; Yan, Shuli; Salley, Steven O.; Ng, K. Y. Simon

2015-10-20

A heterogeneous catalyst system, a method of preparing the catalyst system and a method of forming a biodiesel product via transesterification reactions using the catalyst system is disclosed. The catalyst system according to one aspect of the present disclosure represents a class of supported mixed metal oxides that include at least calcium oxide and another metal oxide deposited on a lanthanum oxide or cerium oxide support. Preferably, the catalysts include CaO--CeO.sub.2ZLa.sub.2O.sub.3 or CaO--La.sub.2O.sub.3/CeO.sub.2. Optionally, the catalyst may further include additional metal oxides, such as CaO--La.sub.2O.sub.3--GdOxZLa.sub.2O.sub.3.

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

Heterogeneous catalysis in liquid-phase oxidation of olefin--2. Dependence of the structure of vanadium-chromium binary oxide catalyst for oxidation of cyclohexene on the method of preparation

Energy Technology Data Exchange (ETDEWEB)

Takehira, K; Hayakawa, T; Ishikawa, T

1978-01-01

Dependence of the structure of vanadium-chromium binary oxide catalyst for oxidation of cyclohexene on the method of preparation was studied in an extension of previous work by using three series of binary oxide catalysts, D, E, and F, which were prepared by coprecipitation from acidic, neutral, and alkaline media, respectively. The specific activity at 60/sup 0/C, 1 atm oxygen, and benzene solvent decreased in the order D > E > F, but all three series showed maximum activity at 90% chromium. The selectivity for epoxide also followed the order D > E > F, but the maximum selectivity occurred at 50% chromium for D, 75% for E, and 90% for F. Comparison of these results with X-ray diffraction and ESR spectral structural analysis of the various chromium(III) vanadate phases supported the previously proposed mechanism, with cyclohexene autoxidation initiated by free radical decomposition of cyclohexene hydroperoxide occurring on a different type of active site.

Vanadium oxides supported on hydrotalcite-type precursors: the effect of acid-base properties on the oxidation of isopropanol

Directory of Open Access Journals (Sweden)

D. M. Meira

2006-09-01

Full Text Available Vanadium oxide supported on hydrotalcite-type precursors was studied in the oxidation of isopropanol. Hydrotalcites with different y = Mg/Al ratios were synthesized by the method of coprecipitation nitrates of Mg and Al cations with K2CO3 as precipitant. The decomposition of these hydrotalcite precursors at 450°C yielded homogeneous MgyAlOx mixed oxides that contain the Al+3 cations totally incorporated into the MgO framework. The materials were characterized by chemical analysis, BET superficial area, X-ray diffraction, temperature-programmed reduction (TPR and the reaction of isopropanol, a probe molecule used to evaluate the acid-base properties. The results of TPR showed that the reducibility of V+5 decreased with the increase in magnesium loading in catalysts. The X-ray diffraction patterns of Al-rich hydrotalcite precursors showed the presence of crystalline phases of brucite and gibbsite. It was shown that chemical composition, texture, acid-base properties of the active sites and also Mg/Al ratio strongly affect the formation of the products in the oxidation of isopropanol. The Al-rich catalysts were much more active than the Mg-rich ones, converting isopropanol mainly to propylene.

Vanadium oxides supported on hydrotalcite-type precursors: the effect of acid base properties on the oxidation of isopropanol

Energy Technology Data Exchange (ETDEWEB)

Meira, D.M.; Cortez, G.G. [Faculdade de Engenharia Quimica de Lorena, Lorena, SP (Brazil). Dept. de Engenharia Quimica. Lab. de Catalise II]. E-mail: cortez@dequi.faenquil.br; Monteiro, W.R.; Rodrigues, J.A.J. [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Lab. Associado de Combustao e Propulsao]. E-mail: jajr@lcp.inpe.br

2006-07-15

Vanadium oxide supported on hydrotalcite-type precursors was studied in the oxidation of isopropanol. Hydrotalcites with different y = Mg/Al ratios were synthesized by the method of coprecipitation nitrates of Mg and Al cations with K{sub 2}CO{sub 3} as precipitant. The decomposition of these hydrotalcite precursors at 450 deg C yielded homogeneous MgyAlOx mixed oxides that contain the Al{sup +3} cations totally incorporated into the MgO framework. The materials were characterized by chemical analysis, BET superficial area, X-ray diffraction, temperature-programmed reduction (TPR) and the reaction of isopropanol, a probe molecule used to evaluate the acid-base properties. The results of TPR showed that the reducibility of V{sup +5} decreased with the increase in magnesium loading in catalysts. The X-ray diffraction patterns of Al-rich hydrotalcite precursors showed the presence of crystalline phases of brucite and gibbsite. It was shown that chemical composition, texture, acid-base properties of the active sites and also Mg/Al ratio strongly affect the formation of the products in the oxidation of isopropanol. The Al-rich catalysts were much more active than the Mg-rich ones, converting isopropanol mainly to propylene. (author)

Attrition resistant Fischer-Tropsch catalyst and support

Science.gov (United States)

Singleton, Alan H.; Oukaci, Rachid; Goodwin, James G.

2004-05-25

A catalyst support having improved attrition resistance and a catalyst produced therefrom. The catalyst support is produced by a method comprising the step of treating calcined .gamma.-alumina having no catalytic material added thereto with an acidic aqueous solution having an acidity level effective for increasing the attrition resistance of the calcined .gamma.-alumina.

Vanadium Electrolyte Studies for the Vanadium Redox Battery-A Review.

Science.gov (United States)

Skyllas-Kazacos, Maria; Cao, Liuyue; Kazacos, Michael; Kausar, Nadeem; Mousa, Asem

2016-07-07

The electrolyte is one of the most important components of the vanadium redox flow battery and its properties will affect cell performance and behavior in addition to the overall battery cost. Vanadium exists in several oxidation states with significantly different half-cell potentials that can produce practical cell voltages. It is thus possible to use the same element in both half-cells and thereby eliminate problems of cross-contamination inherent in all other flow battery chemistries. Electrolyte properties vary with supporting electrolyte composition, state-of-charge, and temperature and this will impact on the characteristics, behavior, and performance of the vanadium battery in practical applications. This Review provides a broad overview of the physical properties and characteristics of the vanadium battery electrolyte under different conditions, together with a description of some of the processing methods that have been developed to produce vanadium electrolytes for vanadium redox flow battery applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Titanium Dioxide as a Catalyst Support in Heterogeneous Catalysis

Science.gov (United States)

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

2014-01-01

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

Surface chemistry and catalytic properties of VOX/Ti-MCM-41 catalysts for dibenzothiophene oxidation in a biphasic system

International Nuclear Information System (INIS)

González, J.; Chen, L.F.; Wang, J.A.; Manríquez, Ma.; Limas, R.; Schachat, P.; Navarrete, J.; Contreras, J.L.

2016-01-01

Highlights: • Oxidative desulfurization of model diesel was tested in a biphasic system. • ODS activity was proportional to the V 5+ /(V 4+ + V 5+ ) values of the catalysts. • Lewis acidity was related to vanadium content and catalytic activity. • 99.9% DBT was oxidized using 25%V 2 O 5 /Ti-MCM-41 at 60 °C within 60 min. - Abstract: A series of vanadium oxide supported on Ti-MCM-41 catalysts was synthesized via the incipient impregnation method by varying the vanadia loading from 5 wt% to 10, 15, 20 and 25 wt%. These catalysts were characterized by a variety of advanced techniques for investigating their crystalline structure, textural properties, and surface chemistry information including surface acidity, reducibility, vanadium oxidation states, and morphological features. The catalytic activities of the catalysts were evaluated in a biphasic reaction system for oxidative desulfurization (ODS) of a model diesel containing 300 ppm of dibenzothiophene (DBT) where acetonitrile was used as extraction solvent and H 2 O 2 as oxidant. ODS activity was found to be proportional to the V 5+ /(V 4+ + V 5+ ) values of the catalysts, indicating that the surface vanadium pentoxide (V 2 O 5 ) was the active phase. Reaction temperature would influence significantly the ODS efficiency; high temperature, i.e., 80 °C, would lead to low ODS reaction due to the partial decomposition of oxidant. All the catalysts contained both Lewis and Brønsted acid sites but the former was predominant. The catalysts with low vanadia loading (5 or 10 wt%V 2 O 5 ) had many Lewis acid sites and could strongly adsorb DBT molecule via the electron donation/acceptance action which resulted in an inhibition for the reaction of DBT with the surface peroxometallic species. The catalyst with high vanadia loading (25wt%V 2 O 5 /Ti-MCM-41) showed the highest catalytic activity and could remove 99.9% of DBT at 60 °C within 60 min.

Immobilization of molecular catalysts in supported ionic liquid phases.

Science.gov (United States)

Van Doorslaer, Charlie; Wahlen, Joos; Mertens, Pascal; Binnemans, Koen; De Vos, Dirk

2010-09-28

In a supported ionic liquid phase (SILP) catalyst system, an ionic liquid (IL) film is immobilized on a high-surface area porous solid and a homogeneous catalyst is dissolved in this supported IL layer, thereby combining the attractive features of homogeneous catalysts with the benefits of heterogeneous catalysts. In this review reliable strategies for the immobilization of molecular catalysts in SILPs are surveyed. In the first part, general aspects concerning the application of SILP catalysts are presented, focusing on the type of catalyst, support, ionic liquid and reaction conditions. Secondly, organic reactions in which SILP technology is applied to improve the performance of homogeneous transition-metal catalysts are presented: hydroformylation, metathesis reactions, carbonylation, hydrogenation, hydroamination, coupling reactions and asymmetric reactions.

Surface chemistry and catalytic properties of VOX/Ti-MCM-41 catalysts for dibenzothiophene oxidation in a biphasic system

Science.gov (United States)

González, J.; Chen, L. F.; Wang, J. A.; Manríquez, Ma.; Limas, R.; Schachat, P.; Navarrete, J.; Contreras, J. L.

2016-08-01

A series of vanadium oxide supported on Ti-MCM-41 catalysts was synthesized via the incipient impregnation method by varying the vanadia loading from 5 wt% to 10, 15, 20 and 25 wt%. These catalysts were characterized by a variety of advanced techniques for investigating their crystalline structure, textural properties, and surface chemistry information including surface acidity, reducibility, vanadium oxidation states, and morphological features. The catalytic activities of the catalysts were evaluated in a biphasic reaction system for oxidative desulfurization (ODS) of a model diesel containing 300 ppm of dibenzothiophene (DBT) where acetonitrile was used as extraction solvent and H2O2 as oxidant. ODS activity was found to be proportional to the V5+/(V4+ + V5+) values of the catalysts, indicating that the surface vanadium pentoxide (V2O5) was the active phase. Reaction temperature would influence significantly the ODS efficiency; high temperature, i.e., 80 °C, would lead to low ODS reaction due to the partial decomposition of oxidant. All the catalysts contained both Lewis and Brønsted acid sites but the former was predominant. The catalysts with low vanadia loading (5 or 10 wt%V2O5) had many Lewis acid sites and could strongly adsorb DBT molecule via the electron donation/acceptance action which resulted in an inhibition for the reaction of DBT with the surface peroxometallic species. The catalyst with high vanadia loading (25wt%V2O5/Ti-MCM-41) showed the highest catalytic activity and could remove 99.9% of DBT at 60 °C within 60 min.

The activity of supported vanadium oxide catalysts for the selective reduction of NO with ammonia

NARCIS (Netherlands)

Bosch, H.; Janssen, Frans J.J.G.; van den Kerkhof, Frans M.G.; Oldenziel, Jaap; van Ommen, J.G.; Ross, Julian R.H.

1986-01-01

The activities of monolayer V2O5 catalysts for the selective reduction of NO with NH3 are compared with those of commercial available catalysts containing V and/or W. From steady state and pulse experiments it can be concluded that the reduction of surface sites proceeds either by NH3 + NO or by NH3

NEXAFS characterization and reactivity studies of bimetallic vanadium molybdenum oxynitride hydrotreating catalysts

Energy Technology Data Exchange (ETDEWEB)

Kapoor, R.; Oyama, S.T. [Virginia Polytechnic Inst., Blacksburg, VA (United States); Fruehberger, B.; Chen, J.G. [Exxon Research and Engineering Company, Annandale, NJ (United States)

1997-02-27

The surface and bulk compositions of vanadium molybdenum oxynitride (V{sub 2}MoO{sub 1.7}N{sub 2.4}), prepared by temperature-programmed reaction (TPR) of vanadium molybdenum oxide (V{sub 2}MoO{sub 8}) with ammonia, have been characterized using near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The NEXAFS data were recorded at the K-edges of nitrogen and oxygen, the L-edge of vanadium, and the M-edge of molybdenum. The nitrogen K-edge region of V-Mo oxynitride shows the characteristic NEXAFS features of early-transition-metal nitrides, although these features are different from those of either VN or Mo{sub 2}N. Furthermore, comparison of the electron yield and fluorescence yield measurements also reveals that the oxidation state is different for vanadium near the surface region and for vanadium in the bulk, which is estimated to be 2.8 {+-} 0.3 and 3.8 {+-} 0.3, respectively. The oxidation state of bulk molybdenum is also estimated to be 4.4 {+-} 0.3. The X-ray diffraction pattern shows that the bulk phase of the bimetallic oxide is different from the pure monometallic oxide phases but the oxynitride has a cubic structure that resembles the pure vanadium and molybdenum nitride phases. The V-Mo oxide as prepared shows a preferential orientation of [001] crystallographic planes which is lost during the nitridation process. This shows that the solid state transformation V{sub 2}MoO{sub 8} {yields} V{sub 2}MoO{sub 1.7}N{sub 2.4} is not topotactic. 27 refs., 8 figs., 1 tab.

Study to determine the content of vanadium, aluminum, nickel, sodium, iron and copper in a catalytic cracking catalyst, by using Atomic Absorption Spectrometry

International Nuclear Information System (INIS)

Gomez, J.; Alonso, A.; Tumbarell, O.; Bustanmete, E.

2003-01-01

Atomic Absorption Spectrometry (AAS), has the advantage of its simplicity, speed and low cost. All this, together with its high sensibility and selectivity, makes the AAS one the most widely used analytic techniques. The present work shows, the study to determine the content of vanadium, aluminum, nickel, sodium, iron and copper in a catalytic cracking catalyst of a refinery, by using this technique. The results are compared to those of two laboratories which use the ICP-AES and AAS techniques and shows the processing of the statistics with the use of the t of Student and the F of Snedecor. The results using different methods are also shown as well as the recommended application of this results in the chemical characterization of this type of catalysts

Thermal decomposition of supported lithium nitrate catalysts

Energy Technology Data Exchange (ETDEWEB)

Ruiz, Maria Lucia [INTEQUI (CONICET-UNSL), 25 de Mayo 384, V. Mercedes, 5730, San Luis (Argentina); Lick, Ileana Daniela [CINDECA (CONICET-UNLP), Calle 47 No 257, La Plata, 1900, Buenos Aires (Argentina); Ponzi, Marta Isabel [INTEQUI (CONICET-UNSL), 25 de Mayo 384, V. Mercedes, 5730, San Luis (Argentina); Castellon, Enrique Rodriguez; Jimenez-Lopez, Antonio [Departamento de Quimica Inorganica, Cristalografia y Mineralogia. Facultad de Ciencias, Universidad de Malaga, Campus de Teatinos, 29071 Malaga (Spain); Ponzi, Esther Natalia, E-mail: eponzi@quimica.unlp.edu.ar [CINDECA (CONICET-UNLP), Calle 47 No 257, La Plata, 1900, Buenos Aires (Argentina)

2010-02-20

New catalysts for soot combustion were prepared by impregnation of different supports (SiO{sub 2}, ZrO{sub 2} and ZrO{sub 2}.nH{sub 2}O) with a LiNO{sub 3} solution and then characterized by means of FTIR, XPS, TGA and UV-vis spectroscopy, whereby the presence of lithium nitrate in the prepared catalysts was identified and quantified. The soot combustion rate using this series of catalysts (LiNO{sub 3}/support) was compared with the activity of a series of impregnated catalysts prepared using LiOH (Li{sub 2}O/supports). Catalysts prepared using LiNO{sub 3} are found to be more active than those prepared using LiOH. The catalytic performance was also studied with a NO/O{sub 2} mixture in the feed, demonstrating that NO increases the combustion rate of soot, probably as a consequence of lithium oxide forming an 'in situ' nitrate ion.

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.

Surface chemistry and catalytic properties of VO{sub X}/Ti-MCM-41 catalysts for dibenzothiophene oxidation in a biphasic system

Energy Technology Data Exchange (ETDEWEB)

González, J. [ESIQIE, Instituto Politécnico Nacional, Av. Instituto Politécnico Nacional s/n, 07738 Col. Zacatenco, Mexico City (Mexico); Chen, L.F., E-mail: lchen@ipn.mx [ESIQIE, Instituto Politécnico Nacional, Av. Instituto Politécnico Nacional s/n, 07738 Col. Zacatenco, Mexico City (Mexico); Wang, J.A.; Manríquez, Ma.; Limas, R. [ESIQIE, Instituto Politécnico Nacional, Av. Instituto Politécnico Nacional s/n, 07738 Col. Zacatenco, Mexico City (Mexico); Schachat, P.; Navarrete, J. [Dirección de Investigación, Instituto Mexicano del Petróleo, Eje Lázaro Cárdenas 152, 07730 México D.F. (Mexico); Contreras, J.L. [Laboratorio de Catálisis y Polímeros, División de Ciencias Básicas e Ingeniería, Universidad Autónoma Metropolitana-A, Av. San Pablo No. 180, 02200 México D.F. (Mexico)

2016-08-30

Highlights: • Oxidative desulfurization of model diesel was tested in a biphasic system. • ODS activity was proportional to the V{sup 5+}/(V{sup 4+} + V{sup 5+}) values of the catalysts. • Lewis acidity was related to vanadium content and catalytic activity. • 99.9% DBT was oxidized using 25%V{sub 2}O{sub 5}/Ti-MCM-41 at 60 °C within 60 min. - Abstract: A series of vanadium oxide supported on Ti-MCM-41 catalysts was synthesized via the incipient impregnation method by varying the vanadia loading from 5 wt% to 10, 15, 20 and 25 wt%. These catalysts were characterized by a variety of advanced techniques for investigating their crystalline structure, textural properties, and surface chemistry information including surface acidity, reducibility, vanadium oxidation states, and morphological features. The catalytic activities of the catalysts were evaluated in a biphasic reaction system for oxidative desulfurization (ODS) of a model diesel containing 300 ppm of dibenzothiophene (DBT) where acetonitrile was used as extraction solvent and H{sub 2}O{sub 2} as oxidant. ODS activity was found to be proportional to the V{sup 5+}/(V{sup 4+} + V{sup 5+}) values of the catalysts, indicating that the surface vanadium pentoxide (V{sub 2}O{sub 5}) was the active phase. Reaction temperature would influence significantly the ODS efficiency; high temperature, i.e., 80 °C, would lead to low ODS reaction due to the partial decomposition of oxidant. All the catalysts contained both Lewis and Brønsted acid sites but the former was predominant. The catalysts with low vanadia loading (5 or 10 wt%V{sub 2}O{sub 5}) had many Lewis acid sites and could strongly adsorb DBT molecule via the electron donation/acceptance action which resulted in an inhibition for the reaction of DBT with the surface peroxometallic species. The catalyst with high vanadia loading (25wt%V{sub 2}O{sub 5}/Ti-MCM-41) showed the highest catalytic activity and could remove 99.9% of DBT at 60 °C within 60 min.

Predicting catalyst-support interactions between metal nanoparticles and amorphous silica supports

Science.gov (United States)

Ewing, Christopher S.; Veser, Götz; McCarthy, Joseph J.; Lambrecht, Daniel S.; Johnson, J. Karl

2016-10-01

Metal-support interactions significantly affect the stability and activity of supported catalytic nanoparticles (NPs), yet there is no simple and reliable method for estimating NP-support interactions, especially for amorphous supports. We present an approach for rapid prediction of catalyst-support interactions between Pt NPs and amorphous silica supports for NPs of various sizes and shapes. We use density functional theory calculations of 13 atom Pt clusters on model amorphous silica supports to determine linear correlations relating catalyst properties to NP-support interactions. We show that these correlations can be combined with fast discrete element method simulations to predict adhesion energy and NP net charge for NPs of larger sizes and different shapes. Furthermore, we demonstrate that this approach can be successfully transferred to Pd, Au, Ni, and Fe NPs. This approach can be used to quickly screen stability and net charge transfer and leads to a better fundamental understanding of catalyst-support interactions.

New antipollution processing of a used refining catalyst and complete recovery of the catalyst metallic components

Energy Technology Data Exchange (ETDEWEB)

Trinh Dinh Chan; Llido, E.

1992-05-15

The used refining catalyst, containing metals such as vanadium, nickel and iron, is first processed by stripping; it is then calcined in critical conditions and heat processed in the presence of a melted alkaline base; the resulting solid matter is then water processed. The antipollution process can be applied to oil fraction hydroconversion or hydroprocessing catalysts.

Vanadia supported on zeolites for SCR of NO by ammonia

DEFF Research Database (Denmark)

Putluru, Siva Sankar Reddy; Riisager, Anders; Fehrmann, Rasmus

2010-01-01

, acidity and micropore structure of the support. Apparently the support hosted the potassium oxide on the acid sites, thereby protecting the active vanadium species from poisoning. Zeolite based catalysts might therefore prove useful for SCR of NO in alkali-containing flue gases from, e.g. biomass fired...

Designing Pd-based supported bimetallic catalysts for environmental applications

OpenAIRE

Nowicka, Ewa; Meenakshisundaram, Sankar

2018-01-01

Supported bimetallic nanoparticulate catalysts are an important class of heterogeneous catalysts for many reactions including selective oxidation, hydrogenation/hydrogenolysis, reforming, biomass conversion reactions, and many more. The activity, selectivity, and stability of these catalysts depend on their structural features including particle size, composition, and morphology. In this review, we present important structural features relevant to supported bimetallic catalysts focusing on Pd...

Thermal and electrochemical stability of tungsten carbide catalyst supports

Energy Technology Data Exchange (ETDEWEB)

Chhina, H. [Ballard Power Systems, 9000 Glenlyon Parkway, Burnaby, BC (Canada); Department of Materials Engineering, University of British Columbia, Vancouver, BC (Canada); Campbell, S. [Ballard Power Systems, 9000 Glenlyon Parkway, Burnaby, BC (Canada); Kesler, O. [Department of Mechanical Engineering, University of British Columbia, Vancouver, BC (Canada)

2007-02-10

The thermal and electrochemical stability of tungsten carbide (WC), with and without a catalyst dispersed on it, have been investigated to evaluate the potential suitability of the material as an oxidation-resistant catalyst support. Standard techniques currently used to disperse Pt on carbon could not be used to disperse Pt on WC, so an alternative method was developed and used to disperse Pt on both commercially available WC and on carbon for comparison of stability. Electrochemical testing was performed by applying oxidation cycles between +0.6 V and +1.8 V to the support-catalyst material combinations and monitoring the activity of the supported catalyst over 100 oxidation cycles. Comparisons of activity change with cumulative oxidation cycles were made between C and WC supports with comparable loadings of catalyst by weight, solid volume, and powder volume. WC was found to be more thermally and electrochemically stable than currently used carbon support material Vulcan XC-72R. However, further optimization of the particle sizes and dispersion of Pt/WC catalyst/support materials and of comparison standards between new candidate materials and existing carbon-based supports are required. (author)

Nitrogen-doped carbon-supported cobalt-iron oxygen reduction catalyst

Science.gov (United States)

Zelenay, Piotr; Wu, Gang

2014-04-29

A Fe--Co hybrid catalyst for oxygen reaction reduction was prepared by a two part process. The first part involves reacting an ethyleneamine with a cobalt-containing precursor to form a cobalt-containing complex, combining the cobalt-containing complex with an electroconductive carbon supporting material, heating the cobalt-containing complex and carbon supporting material under conditions suitable to convert the cobalt-containing complex and carbon supporting material into a cobalt-containing catalyst support. The second part of the process involves polymerizing an aniline in the presence of said cobalt-containing catalyst support and an iron-containing compound under conditions suitable to form a supported, cobalt-containing, iron-bound polyaniline species, and subjecting said supported, cobalt-containing, iron bound polyaniline species to conditions suitable for producing a Fe--Co hybrid catalyst.

Ni Catalysts Supported on Modified Alumina for Diesel Steam Reforming

Directory of Open Access Journals (Sweden)

Antonios Tribalis

2016-01-01

Full Text Available Nickel catalysts are the most popular for steam reforming, however, they have a number of drawbacks, such as high propensity toward coke formation and intolerance to sulfur. In an effort to improve their behavior, a series of Ni-catalysts supported on pure and La-, Ba-, (La+Ba- and Ce-doped γ-alumina has been prepared. The doped supports and the catalysts have been extensively characterized. The catalysts performance was evaluated for steam reforming of n-hexadecane pure or doped with dibenzothiophene as surrogate for sulphur-free or commercial diesel, respectively. The undoped catalyst lost its activity after 1.5 h on stream. Doping of the support with La improved the initial catalyst activity. However, this catalyst was completely deactivated after 2 h on stream. Doping with Ba or La+Ba improved the stability of the catalysts. This improvement is attributed to the increase of the dispersion of the nickel phase, the decrease of the support acidity and the increase of Ni-phase reducibility. The best catalyst of the series doped with La+Ba proved to be sulphur tolerant and stable for more than 160 h on stream. Doping of the support with Ce also improved the catalytic performance of the corresponding catalyst, but more work is needed to explain this behavior.

Mn3O4 anchored on carbon nanotubes as an electrode reaction catalyst of V(IV)/V(V) couple for vanadium redox flow batteries

International Nuclear Information System (INIS)

He, Zhangxing; Dai, Lei; Liu, Suqin; Wang, Ling; Li, Chuanchang

2015-01-01

Highlights: • Mn 3 O 4 /MWCNTs (multi-walled carbon nanotubes) composite fabricated by a simple solvothermal method was developed as electrochemical catalyst of V(IV)/V(V) redox couple for vanadium redox flow batteries for the first time. • The electrocatalytic kinetics of the redox reactions of three electrocatalysts (pure Mn 3 O 4 , pure MWCNTs, Mn 3 O 4 /MWCNTs) were compared, and were in the order of Mn 3 O 4 /MWCNTs > MWCNTs > Mn 3 O 4 . • The cell using Mn 3 O 4 /MWCNTs has lower electrochemical polarization, with larger discharge capacity and energy efficiency. The average energy efficiency of the cell using Mn 3 O 4 /MWCNTs is 84.65%, 3.73% higher than that of the pristine cell. - Abstract: Mn 3 O 4 /MWCNTs (multi-walled carbon nanotubes) composite fabricated by a simple solvothermal method was developed as electrochemical catalyst of V(IV)/V(V) redox couple for vanadium redox flow batteries. The electrochemical activity of V(IV)/V(V) redox couple can be enhanced by the electrochemical catalysts (Mn 3 O 4 , MWCNTs, Mn 3 O 4 /MWCNTs), and the electrocatalytic kinetics of the redox reactions were in the order of Mn 3 O 4 /MWCNTs > MWCNTs > Mn 3 O 4 . The cell using Mn 3 O 4 /MWCNTs composite as electrochemical catalyst was assembled and the charge-discharge performance was evaluated. Compared with the pristine cell, the cell using positive graphite felt modified by Mn 3 O 4 /MWCNTs had lower electrochemical polarization, larger discharge capacity and energy efficiency. The average energy efficiency of the cell using modified positive electrode for 50 cycles was 84.65%, 3.73% higher than that of the pristine cell. The superior electrocatalytic performance of Mn 3 O 4 /MWCNTs composite was mainly due to the effective mixed conducting network, facilitating the electron transport and ion diffusion in the electrode/electrolyte interface

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

with compositions 25Fe75Ni and 50Fe50Ni showed significantly better activity and in some cases also a higher selectivity to methane compared with the traditional monometallic Ni and Fe catalysts. A catalyst with composition 25Fe75Ni was found to be the most active in CO hydrogenation for the MgAl2O4 support at low...... metal loadings. At high metal concentrations, the maximum for the methanation activity was found for catalysts with composition 50Ni50Fe both on the MgAl2O4 and Al2O3 supports. This difference can be attributed to a higher reducibility of the constituting metals with increasing metal concentration......DFT calculations combined with a computational screening method have previously shown that bimetallic Ni-Fe alloys should be more active than the traditional Ni-based catalyst for CO methanation. That was confirmed experimentally for a number of bimetallic Ni-Fe catalysts supported on MgAl2O4. Here...

Supported chromium-molybdenum and tungsten sulfide catalysts

International Nuclear Information System (INIS)

Chianelli, R.R.; Jacobson, A.J.; Young, A.R.

1988-01-01

This patent describes the process for preparing a supported hydroprocessing catalyst. The process comprising compositing a quantity of a particulate, porous catalyst support material comprising one or more refactory oxides with one or more catalyst precursor salts and heating the composite at elevated temperature of at least about 200/sup 0/C up to about 600/sup 0/, in the presence of a sulfur-bearing compound in an amount whereby sulfur in the form of the sulfur-bearing compound in an amount whereby sulfur in the form of the sulfur bearing compound is present in excess of that contained in the catalyst precursor and under oxygen-free conditions for a time sufficient to form the catalyst. The catalyst precursor salt contains a tetrathiometallate anion of Mo, W or mixture therof and a cation comprising trivalent chromium or a mixture of trivalent chromium with one or more divalent promoter metals selected from the group consisting of Fe, Ni, Co, Mn, Cu and a mixture thereof wherein the trivalent chromium and divalent promoter metals are chelated by at least one neutral, nitrogen-containing polydentate ligand, L

Mordenite - Type Zeolite SCR Catalysts with Iron or Copper

DEFF Research Database (Denmark)

2012-01-01

Cu/mordenite catalysts were found to be highly active for the SCR of NO with NH3 and exhibited high resistance to alkali poisoning. Redox and acidic properties of Cu/mordenite were well preserved after poisoning with potassium unlike that of vanadium catalysts. Fe-mordenite catalysts also reveale...... to be essential requirements for the high alkali resistance. Mordenite-type zeolite based catalysts could therefore be attractive alternatives to conventional SCR catalysts for biomass fired power plant flue gas treatment....

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...... catalyst. The results from the screening were experimentally verified for CO hydrogenation, CO2 hydrogenation, and simultaneous CO and CO2 hydrogenation by bimetallic Ni-Fe catalysts. These catalysts were found to be highly active and selective. The Co-Ni and Co-Fe systems were investigated for CO...... 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...

Comparison of Elemental Mercury Oxidation Across Vanadium and Cerium Based Catalysts in Coal Combustion Flue Gas: Catalytic Performances and Particulate Matter Effects.

Science.gov (United States)

Wan, Qi; Yao, Qiang; Duan, Lei; Li, Xinghua; Zhang, Lei; Hao, Jiming

2018-03-06

This paper discussed the field test results of mercury oxidation activities over vanadium and cerium based catalysts in both coal-fired circulating fluidized bed boiler (CFBB) and chain grate boiler (CGB) flue gases. The characterizations of the catalysts and effects of flue gas components, specifically the particulate matter (PM) species, were also discussed. The catalytic performance results indicated that both catalysts exhibited mercury oxidation preference in CGB flue gas rather than in CFBB flue gas. Flue gas component studies before and after dust removal equipment implied that the mercury oxidation was well related to PM, together with gaseous components such as NO, SO 2 , and NH 3 . Further investigations demonstrated a negative PM concentration-induced effect on the mercury oxidation activity in the flue gases before the dust removal, which was attributed to the surface coverage by the large amount of PM. In addition, the PM concentrations in the flue gases after the dust removal failed in determining the mercury oxidation efficiency, wherein the presence of different chemical species in PM, such as elemental carbon (EC), organic carbon (OC) and alkali (earth) metals (Na, Mg, K, and Ca) in the flue gases dominated the catalytic oxidation of mercury.

Polymer-Supported Raney Nickel Catalysts for Sustainable Reduction Reactions

Directory of Open Access Journals (Sweden)

Haibin Jiang

2016-06-01

Full Text Available Green is the future of chemistry. Catalysts with high selectivity are the key to green chemistry. Polymer-supported Raney catalysts have been found to have outstanding performance in the clean preparation of some chemicals. For example, a polyamide 6-supported Raney nickel catalyst provided a 100.0% conversion of n-butyraldehyde without producing any detectable n-butyl ether, the main byproduct in industry, and eliminated the two main byproducts (isopropyl ether and methyl-iso-butylcarbinol in the hydrogenation of acetone to isopropanol. Meanwhile, a model for how the polymer support brought about the elimination of byproducts is proposed and confirmed. In this account the preparation and applications of polymer-supported Raney catalysts along with the corresponding models will be reviewed.

Heterogenization of Homogeneous Catalysts: the Effect of the Support

Energy Technology Data Exchange (ETDEWEB)

Earl, W.L.; Ott, K.C.; Hall, K.A.; de Rege, F.M.; Morita, D.K.; Tumas, W.; Brown, G.H.; Broene, R.D.

1999-06-29

We have studied the influence of placing a soluble, homogeneous catalyst onto a solid support. We determined that such a 'heterogenized' homogeneous catalyst can have improved activity and selectivity for the asymmetric hydrogenation of enamides to amino acid derivatives. The route of heterogenization of RhDuPhos(COD){sup +} cations occurs via electrostatic interactions with anions that are capable of strong hydrogen bonding to silica surfaces. This is a novel approach to supported catalysis. Supported RhDuPhos(COD){sup +} is a recyclable, non-leaching catalyst in non-polar media. This is one of the few heterogenized catalysts that exhibits improved catalytic performance as compared to its homogeneous analog.

57Fe Moessbauer Studies in Mo-Fe Supported Catalysts

International Nuclear Information System (INIS)

Castelao-Dias, M.; Costa, B. F. O.; Quinta-Ferreira, R. M.

2001-01-01

Industrially, the Mo-Fe catalysts used in the selective oxidation of methanol to formaldehyde can rapidly deactivate. The use of support materials may reduce the high temperatures in the catalytic bed and/or increase thermal and mechanical resistance. However, during the preparation of these catalysts, or even during reaction conditions, the active species may react with the support material losing their catalytic activity. In this work silica, silicium carbide and titania were studied as supported catalysts by Moessbauer spectroscopy which proved to be a useful technique in the choice of supported materials

Synthesis and characterization of group V metal carbide and nitride catalysts

Science.gov (United States)

Kwon, Heock-Hoi

1998-11-01

Group V transition metal carbides and nitrides were prepared via the temperature programmed reaction (TPR) of corresponding oxides with NHsb3 or a CHsb4/Hsb2 mixture. Except for the tantalum compounds, phase-pure carbides and nitrides were prepared. The vanadium carbides and nitrides were the most active and selective catalysts. Therefore the principal focus of the research was the preparation, characterization, and evaluation of high surface area vanadium nitride catalysts. A series of vanadium nitrides with surface areas up to 60 msp2/g was prepared. Thermal gravimetric analysis coupled with x-ray diffraction and scanning electron microscopy indicated that the solid-state reaction proceeded by the sequential reduction of Vsb2Osb5 to VOsb{0.9} and concluded with the topotactic substitution of nitrogen for oxygen in VOsb{0.9}. The transformation of Vsb2Osb5 to VN was pseudomorphic. An experimental design was executed to determine effects of the heating rates and space velocities on the VN microstructures. The heating rates had minor effects on the surface areas and pore size distributions; however, increasing the space velocity significantly increased the surface area. The materials were mostly mesoporous. Oxygen chemisorption on the vanadium nitrides scaled linearly with the surface area. The corresponding O/Vsbsurface ratio was ≈0.6. The vanadium nitrides were active for butane activation and pyridine hydrodenitrogenation. During butane activation, their selectivities towards dehydrogenation products were as high as 98%. The major product in pyridine hydrodenitrogenation was pentane. The reaction rates increased almost linearly with the surface area suggesting that these reactions were structure insensitive. The vanadium nitrides were not active for crotonaldehyde hydrogenation; however, they catalyzed an interesting ring formation reaction that produced methylbenzaldehyde and xylene from crotonaldehyde. A new method was demonstrated for the production of very

Polypropylene obtained through zeolite supported catalysts

Directory of Open Access Journals (Sweden)

Queli C. Bastos

2004-01-01

Full Text Available Propylene polymerizations were carried out with f2C(Flu(CpZrCl2 and SiMe2(Ind2ZrCl2 catalysts supported on silica, zeolite sodic mordenite (NaM and acid mordenite (HM. The polymerizations were performed at different temperatures and varying aluminium/zirconium molar ratios ([Al]/[Zr]. The effect of these reaction parameters on the catalyst activity was investigated using a proposed statistical experimental planning. In the case of f2C(Flu(CpZrCl2, SiO2 and NaM were used as support and the catalyst performance evaluated using toluene and pentane as polymerization solvent. The molecular weight, molecular weight distribution, melting point and crystallinity of the polymers were examined. The results indicate very high activities for the syndiospecific heterogeneous system. Also, the polymers obtained had superior Mw and stereoregularity.

Polypropylene obtained through zeolite supported catalysts

International Nuclear Information System (INIS)

Bastos, Queli C.; Marques, Maria de Fatima V.

2004-01-01

Propylene polymerizations were carried out with φ 2 C(Flu)(Cp)ZrCl 2 and SiMe 2 (Ind)2ZrCl 2 catalysts supported on silica, zeolite sodic mordenite (NaM) and acid mordenite (HM). The polymerizations were performed at different temperatures and varying aluminium/zirconium molar ratios ([Al]/[Zr]). The effect of these reaction parameters on the catalyst activity was investigated using a proposed statistical experimental planning. In the case of f 2 C(Flu)(Cp)ZrCl 2 , SiO 2 and NaM were used as support and the catalyst performance evaluated using toluene and pentane as polymerization solvent. The molecular weight, molecular weight distribution, melting point and crystallinity of the polymers were examined. The results indicate very high activities for the syndiospecific heterogeneous system. Also, the polymers obtained had superior Mw and stereo regularity. (author)

Propene Hydroformylation by Supported Aqueous-phase Rh-NORBOS Catalysts

DEFF Research Database (Denmark)

Riisager, Anders; Eriksen, Kim Michael; Hjortkjær, Jes

2003-01-01

The gas-phase hydroformylation reaction of propene using supported aqueous-phase (SAP) Rh-NORBOS modified catalysts in a continuous flow reactor has been examined. SAP catalysts supported on six different support materials were made by wet impregnation using solutions of the precursor complex Rh(...

Catalyst support effects on hydrogen spillover

Science.gov (United States)

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

2017-01-01

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

Interfacial charge distributions in carbon-supported palladium catalysts

DEFF Research Database (Denmark)

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

2017-01-01

Controlling the charge transfer between a semiconducting catalyst carrier and the supported transition metal active phase represents an elite strategy for fine turning the electronic structure of the catalytic centers, hence their activity and selectivity. These phenomena have been theoretically...... and experimentally elucidated for oxide supports but remain poorly understood for carbons due to their complex nanoscale structure. Here, we combine advanced spectroscopy and microscopy on model Pd/C samples to decouple the electronic and surface chemistry effects on catalytic performance. Our investigations reveal...... treatments can be used to tune the interfacial charge distribution, hereby providing a strategy to rationally design carbon-supported catalysts.Control over charge transfer in carbon-supported metal nanoparticles is essential for designing new catalysts. Here, the authors show that thermal treatments...

Nitrogen-doped carbon nanotubes as a metal catalyst support

CSIR Research Space (South Africa)

Mabena, LF

2011-05-01

Full Text Available ., which are among the most commonly used heterogeneous catalyst supports (Mart??nez-Me?ndez et al. 2006). Catalyst activity depends on the particle size and appropriate dis- tance between each particle. These catalysts deposited on a support... supported Pt electrodes. Appl Catal B Environ 80:286?295 Maldonado S, Morin S, Stevenson KJ (2006) Structure, composition, and chemical reactivity of carbon nanotubes by selective nitrogen doping. Carbon 44:1429?1437 Mart??nez-Me?ndez S, Henr??quez Y...

Antipollution processing of a used refining catalyst and metal recovery

Energy Technology Data Exchange (ETDEWEB)

Trinh Dinh Chan; Llido, E.

1992-04-30

The used catalyst, containing metals such as vanadium, nickel and iron, is unloaded from the plant and is first processed by stripping; it is then calcined in critical conditions, and the catalyst metals are leached with a sodium hydroxide or sodium carbonate aqueous solution. The antipollution process can be applied to oil fraction hydroconversion or hydroprocessing catalysts.

SiC nanocrystals as Pt catalyst supports for fuel cell applications

DEFF Research Database (Denmark)

Dhiman, Rajnish; Morgen, Per; Skou, E.M.

2013-01-01

A robust catalyst support is pivotal to Proton Exchange Membrane Fuel Cells (PEMFCs) to overcome challenges such as catalyst support corrosion, low catalyst utilization and overall capital cost. SiC is a promising candidate material which could be applied as a catalyst support in PEMFCs. Si...... on the nanocrystals of SiC-SPR and SiC-NS by the polyol method. The SiC substrates are subjected to an acid treatment to introduce the surface groups, which help to anchor the Pt nano-catalysts. These SiC based catalysts have been found to have a higher electrochemical activity than commercially available Vulcan...... based catalysts (BASF & HISPEC). These promising results signal a new era of SiC based catalysts for fuel cell applications....

Attrition Resistant Fischer-Tropsch Catalysts Based on FCC Supports

Energy Technology Data Exchange (ETDEWEB)

Adeyiga, Adeyinka

2010-02-05

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

Hydrogenation of carbon monoxide over supported palladium catalysts

Energy Technology Data Exchange (ETDEWEB)

Fujimoto, K.; Hashimoto, H.; Kunugi, T.

1978-03-01

An alumina-supported 2% palladium catalyst had higher activity for carbon monoxide hydrogenation than a silica-supported 2% palladium catalyst, at 250/sup 0/-400/sup 0/C and 1 atm. The addition of lanthanum oxide or thorium oxide, but not of potassium oxide, to the silica-supported catalyst increased the conversion at 350/sup 0/C from 1.1% to 81.0% with a selectivity of 56.1% for methane, 1.4% for C/sub 2/ compounds, 0.1% for C/sub 3/ compounds, and 42.5% for carbon dioxide. Temperature-programed desorption of carbon monoxide in a hydrogen stream showed that of two desorption peaks observed for carbon monoxide, the one at higher temperature corresponded to the carbon monoxide species which hydrogenates to methane and that the area of this peak increased with increasing thorium content of the catalyst. Graphs, tables, and 12 references.

Zircon Supported Copper Catalysts for the Steam Reforming of Methanol

Science.gov (United States)

Widiastri, M.; Fendy, Marsih, I. N.

2008-03-01

Steam reforming of methanol (SRM) is known as one of the most favorable catalytic processes for producing hydrogen. Current research on zirconia, ZrO2 supported copper catalyst revealed that CuO/ZrO2 as an active catalyst for the SRM. Zircon, ZrSiO4 is available from the by-product of tin mining. In the work presented here, the catalytic properties of CuO/ZrSiO4 with various copper oxide compositions ranging from 2.70% (catalyst I), 4.12% (catalyst II), and 7.12%-mass (catalyst III), synthesized by an incipient wetness impregnation technique, were investigated to methanol conversion, selectivity towards CO formation, and effect of ZnO addition (7.83%CuO/8.01%ZnO/ZrSiO4 = catalyst V). The catalytic activity was obtained using a fixed bed reactor and the zircon supported catalyst activity was compared to those of CuO/ZnO/Al2O3 catalyst (catalyst IV) and commercial Kujang LTSC catalyst. An X-ray powder diffraction (XRD) analysis was done to identify the abundant phases of the catalysts. The catalysts topography and particle diameter were measured with scanning electron microscopy (SEM) and composition of the catalysts was measured by SEM-EDX, scanning electron microscope-energy dispersive using X-ray analysis. The results of this research provide information on the possibility of using zircon (ZrSiO4) as solid support for SRM catalysts.

Support Functionalization To Retard Ostwald Ripening in Copper Methanol Synthesis Catalysts

NARCIS (Netherlands)

van den Berg, Roy; Parmentier, Tanja E.; Elkjaer, Christian F.; Gommes, Cedric J.; Sehested, Jens; Helveg, Stig; de Jongh, Petra E.; de Jong, Krijn P.

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

Activation of vanadium-based Ziegler-Natta catalysts by halocarbons for ethylene polymerization: results and mechanism

International Nuclear Information System (INIS)

Deffieux, A.; Amorin, C.; Fontanille, M.; Adisson, E.; Bujadoux, K.

1994-01-01

The reactions for the low productivity of the heterogeneous and homogenous V-based catalysts in the synthesis of LLDPE were discussed and some routes of improving their activity and stability were proposed. Ethylene polymerizations were performed in the isododecane solutions at 160 C and under constant ethylene pressure of 5 bars. One Ti-based catalytic system (TiCl 3 - 0.3 AlCl 3 ) and two V-based systems (TiCl 3 - 0.3 AlCl 3 and VCl 4 ) were investigated. The main reason of activity loss is a rapid reduction of V 4+ and V 3+ to inactive V 2+ form. AlR 3 cocatalysts are also involved in the deactivation process. The effect of addition to the system of various alkyl halides (a.o. of CCl 4 , CH 3 Cl 3 , CF 3 CCCl 3 , CHCl 3 , CHBr 3 , CH 2 Cl 2 , CH 2 BrCl and CH 2 Br 2 ) on the yield of polyethylene was investigated. The alkyl halides act as efficient activators for the heterogeneous and homogeneous vanadium catalysts in the high temperature ethylene polymerization and its copolymerization with 1-hexane. The effect of the presence of CHCl 3 on the short chain branching and the molecular weight distribution (GPC) of these copolymers was also investigated. Halocarbons do not act as chain transfer agents. The peak molecular weight remains almost unchanged but a narrowing of molecular weight distribution is observed due to the suppression of the amount of high-molecular-weight fraction in polymer. (author). 4 refs, 3 figs, 2 tabs

Mechanism of 1, 1-d2 propene oxidation over oxide catalysts

International Nuclear Information System (INIS)

Portefaix, J.L.; Figueras, F.; Forissier, M.

1980-01-01

CD 2 CHCH 3 was oxidized over bismuth molybdate, tin-antimony mixed oxides and supported molybdenum and vanadium oxide catalysts. The deuterium retention is high ( > 90%) in the recovered propene. Percentage retentions of deuterium in the acrolein agree with literature data when bismuth molybdate is used as catalyst. On Sb-Sn-O and supported Mo and V oxides, no isotope effect is noticed for the abstraction of the second hydrogen from the olefin. The slow step of the reaction may therefore be different for the oxidation of propene on Bi-Mo-O and Sb-Sn-O. The ethanal produced by oxidation of CD 2 CHCH 3 contains only minor amounts of deuterium, whatever the catalyst used. It is suggested that partial oxidation of propene to acrolein and C-C bond rupture are parallel reactions which involve different intermediates. Possible mechanisms adapted from organic chemistry are presented to explain these findings. 4 tables

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.

Molecular metal catalysts on supports: organometallic chemistry meets surface science.

Science.gov (United States)

Serna, Pedro; Gates, Bruce C

2014-08-19

Recent advances in the synthesis and characterization of small, essentially molecular metal complexes and metal clusters on support surfaces have brought new insights to catalysis and point the way to systematic catalyst design. We summarize recent work unraveling effects of key design variables of site-isolated catalysts: the metal, metal nuclearity, support, and other ligands on the metals, also considering catalysts with separate, complementary functions on supports. The catalysts were synthesized with the goal of structural simplicity and uniformity to facilitate incisive characterization. Thus, they are essentially molecular species bonded to porous supports chosen for their high degree of uniformity; the supports are crystalline aluminosilicates (zeolites) and MgO. The catalytic species are synthesized in reactions of organometallic precursors with the support surfaces; the precursors include M(L)2(acetylacetonate)1-2, with M = Ru, Rh, Ir, or Au and the ligands L = C2H4, CO, or CH3. Os3(CO)12 and Ir4(CO)12 are used as precursors of supported metal clusters, and some such catalysts are made by ship-in-a-bottle syntheses to trap the clusters in zeolite cages. The simplicity and uniformity of the supported catalysts facilitate precise structure determinations, even in reactive atmospheres and during catalysis. The methods of characterizing catalysts in reactive atmospheres include infrared (IR), extended X-ray absorption fine structure (EXAFS), X-ray absorption near edge structure (XANES), and nuclear magnetic resonance (NMR) spectroscopies, and complementary methods include density functional theory and atomic-resolution aberration-corrected scanning transmission electron microscopy for imaging of individual metal atoms. IR, NMR, XANES, and microscopy data demonstrate the high degrees of uniformity of well-prepared supported species. The characterizations determine the compositions of surface metal complexes and clusters, including the ligands and the metal-support

Bronsted acid site number evaluation using isopropylamine decomposition on Y-zeolite contaminated with vanadium in a simultaneous DSC-TGA analyzer

International Nuclear Information System (INIS)

Osorio Perez, Yonnathan; Forero, Liliam Alexandra Palomeque; Torres, Diana Vanessa Cristiano; Trujillo, Carlos Alexander

2008-01-01

Acid-site catalyzed decomposition of isopropylamine was followed in a simultaneous DSC-TGA analyzer. USY zeolite samples with and without vanadium were studied. Results show that acid sites number decreases linearly with vanadium concentration in zeolite indicating that vanadium neutralizes acid sites on catalyst and the metal is able to move on the surface of the solid. The neutralizing species probably contain only one vanadium atom. The reaction enthalpy plus desorption heat of the products show that vanadium preferentially neutralizes the strongest acid sites on the zeolite. The application of the simultaneous DSC-TGA technique to quantify Bronsted acid sites on solids by this reaction is novel

Sulfidation of carbon-supported iron oxide catalysts

NARCIS (Netherlands)

Ramselaar, W.L.T.M.; Hadders, R.H.; Gerkema, E.; Beer, de V.H.J.; Oers, van E.M.; Kraan, van der A.M.

1989-01-01

The sulfidation of carbon-supported iron oxide catalysts was studied by means of in-situ Mössbauer spectroscopy at temperatures down to 4.2 K. The catalysts were dried in two different ways and then sulfided in a flow of 10% H2S in H2 at temperatures between 293 and 773 K. Thiophene

Vanadium oxide (VO) based low cost counter electrode in dye sensitized solar cell (DSSC) applications

Energy Technology Data Exchange (ETDEWEB)

Vijayakumar, P.; Pandian, Muthu Senthil; Ramasamy, P., E-mail: ramasamyp@ssn.edu.in [SSN Research Centre, SSN College of Engineering, Kalavakkam-603 110, Chennai, Tamilnadu (India)

2015-06-24

Vanadium oxide nanostars were synthesized by chemical method. The prepared Vanadium oxide nanostars are introduced into dye sensitized solar cell (DSSC) as counter electrode (CE) catalyst to replace the expensive platinum (Pt). The products were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) method. The photovoltaic performance of the VO as counter electrode based DSSC was evaluated under simulated standard global AM 1.5G sunlight (100 mW/cm{sup 2}). The solar to electrical energy conversion efficiency (η) of the DSSC was found to be 0.38%.This work expands the Counter electrode catalyst, which can help to reduce the cost of DSSC and thereby encourage their fundamental research and commercial application.

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

Science.gov (United States)

Li, Kuo-Tseng; Wu, Ling-Huey

2017-05-05

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

Metal Phosphate-Supported Pt Catalysts for CO Oxidation

Directory of Open Access Journals (Sweden)

Xiaoshuang Qian

2014-12-01

Full Text Available Oxides (such as SiO2, TiO2, ZrO2, Al2O3, Fe2O3, CeO2 have often been used to prepare supported Pt catalysts for CO oxidation and other reactions, whereas metal phosphate-supported Pt catalysts for CO oxidation were rarely reported. Metal phosphates are a family of metal salts with high thermal stability and acid-base properties. Hydroxyapatite (Ca10(PO46(OH2, denoted as Ca-P-O here also has rich hydroxyls. Here we report a series of metal phosphate-supported Pt (Pt/M-P-O, M = Mg, Al, Ca, Fe, Co, Zn, La catalysts for CO oxidation. Pt/Ca-P-O shows the highest activity. Relevant characterization was conducted using N2 adsorption-desorption, inductively coupled plasma (ICP atomic emission spectroscopy, X-ray diffraction (XRD, transmission electron microscopy (TEM, CO2 temperature-programmed desorption (CO2-TPD, X-ray photoelectron spectroscopy (XPS, and H2 temperature-programmed reduction (H2-TPR. This work furnishes a new catalyst system for CO oxidation and other possible reactions.

Study of the catalytic activity of supported technetium catalysts

International Nuclear Information System (INIS)

Spitsyn, V.I.; Mikhailenko, I.E.; Pokorovskaya, O.V.

1985-01-01

The radioactive d metal 43 Tc 99 has catalytic properties in the synthesis of ammonia. For the purpose of reducing the quantity of the radioactive metal and of increasing the specific surface, the active component was applied to BaTiO 3 and gamma-Al 2 O 3 supports. This paper uses charcoal as a support and a table presents the catalytic activity of the samples during the synthesis of ammonia. X-ray diffractometric investigation of the catalysts was carried out with the use of Cu K /SUB alpha/ radiation. It is shown that the catalysts. The values of the specific rate constants of technetium in the catalysts. The values of the specific rate constants remain practically constant for all the catalyst samples studied, attesting to the absence of a specific metal-support interaction during the synthesis of ammonia

Progress on the mechanistic understanding of SO2 oxidation catalysts

DEFF Research Database (Denmark)

Lapina, Olga B.; Bal'zhinimaev, B.S.; Boghosian, Soghomon

1999-01-01

Production, Goskhimizdat (in Russian), Moscow, 1954, p. 348]. In recent years these catalysts have also been used to clean flue gases and other SO; containing, industrial off-gases. In spite of the importance and long utilization of these industrial processes, the catalytic active species and the reaction......For almost a century vanadium oxide based catalysts have been the dominant materials in industrial processes for sulfuric acid production. A vast body of information leading to fundamental knowledge on the catalytic process was obtained by Academician [G.K. Boreskov, Catalysis in Sulphuric Acid...... mechanism. A multiinstrumental investigation that combine the efforts of four groups from four different countries has been carried out on the model system as well as on working industrial catalysts. Detailed information has been obtained on the complex and on the redox chemistry of vanadium. Based on this...

Sulfur tolerant zeolite supported platinum catalysts for aromatics hydrogenation

Energy Technology Data Exchange (ETDEWEB)

Bergem, Haakon

1997-12-31

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

Hydroprocessing using regenerated spent heavy hydrocarbon catalyst

International Nuclear Information System (INIS)

Clark, F.T.; Hensley, A.L. Jr.

1992-01-01

This patent describes a process for hydroprocessing a hydrocarbon feedstock. It comprises: contacting the feedstock with hydrogen under hydroprocessing conditions with a hydroprocessing catalyst wherein the hydroprocessing catalyst contains a total contaminant metals build-up of greater than about 4 wt. % nickel plus vanadium, a hydrogenation component selected from the group consisting of Group VIB metals and Group VIII metals and is regenerated spent hydroprocessing catalyst regenerated by a process comprising the steps: partially decoking the spent catalyst in an initial coke-burning step; impregnating the partially decoked catalyst with a Group IIA metal-containing impregnation solution; and decoking the impregnated catalyst in a final coke-burning step wherein the impregnated catalyst is contacted with an oxygen-containing gas at a temperature of about 600 degrees F to about 1400 degrees F

Montmorillonite Supported Titanium/Antimony Catalyst:Preparation, Characterization and Immobilization

Institute of Scientific and Technical Information of China (English)

CHEN Guiyong; WANG Xiaoqun; ZHAO Chuan; DU Shanyi

2014-01-01

Montmorillonite supported titanium (Ti-MMT) or antimony catalyst (Sb-MMT) has been a hot area of research on preparing polyethylene terephthalate/montmorillonite (PET/MMT) nanocomposites by in situ polymerization. So removal of Ti or Sb from Ti-MMT or Sb-MMT is not expected during in situ polymerization. Studies on immobilization of Ti or Sb on Ti-MMT or Sb-MMT are seldom reported. In this work, a series of montmorillonite supported catalysts of titanium (Ti-MMT) or antimony (Sb-MMT) and co-intercalated montmorillonite of titanium and antimony (Ti/Sb-MMT) were prepared by (1) the reaction of sodium bentonite suspension with intercalating solution containing titanium tetrachloride and/or antimony chloride, and (2) drying or calcinating the products at different temperature (100, 150, 240, 350 and 450℃). The physicochemical properties of these MMT supported catalysts were studied by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), inductively coupled plasma optical emission spectrometer (ICPOES), N2 adsorption/desorption isotherms, UV-visible diffuse reflectance spectroscopy(UV-vis) and transmission electron microscopy (TEM). The immobile character of Ti or Sb on MMT supported catalysts was evaluated by a two-step method in deionized water or ethylene glycol. Several results were obtained, i e, (a) during the preparation, with an increase in drying or calcinating temperature, the amount of titanium and/or antimony species remained on these MMT supported catalysts decreased, (b) the experiments about immobile character of Ti or/and Sb showed that with an increase in drying or calcinating temperature, the immobilization of Ti and/or Sb species remained on these MMT supported catalysts increased gradually, (c) Ti-MMT calcinated at 450℃had the biggest pore volume, which means Ti-MMT had the best adsorption application prospect.

Sulphur poisoning of palladium catalysts used for methane combustion: Effect of the support

International Nuclear Information System (INIS)

Escandon, Lara S.; Ordonez, Salvador; Vega, Aurelio; Diez, Fernando V.

2008-01-01

Four different supported palladium catalysts (using alumina, silica, zirconia and titania as supports), prepared by incipient wetness impregnation, were tested as catalysts for methane oxidation in presence of sulphur dioxide. The catalyst supported on zirconia showed the best performance, whereas the silica-supported one showed the fastest deactivation. Temperature-programmed desorption experiments of the poisoned catalysts suggest that SO 2 adsorption capacity of the support plays a key role in the catalyst poisoning. In order to study the effect of promoters, expected to improve the thermal stability and thioresistance of the catalyst, commercial zirconia modified by yttrium and lantane was tested as supports. It was found that the presence of these promoters does not improve the performance of the zirconia-supported catalyst. A deactivation model - considering two different active sites (fresh and poisoning), pseudo-first order dependence on methane concentration and poisoning rate depending on sulphur concentration and fraction of non-poisoned palladium - was used for modelling the deactivation behaviour

Recycling of spent hydroprocessing catalysts: EURECAT technology

Energy Technology Data Exchange (ETDEWEB)

Berrebi, G.; Dufresne, P.; Jacquier, Y. (EURECAT-European Reprocessing Catalysts, La Voulte sur Rhone (France))

1994-04-01

Disposal of spent catalyst is a growing concern for all refiners. Environmental regulations are becoming stricter and stricter and there are State recommendations to develop disposal routes which would emphasize recycling as much as possible, and processing the wastes as near as possible to the production center. In this context, EURECAT has developed a recycling process for the hydroprocessing catalysts used in the oil refineries (NiMo, CoMo, NiW on alumina or mixed alumina silica). The process starts with a regeneration of the catalyst to eliminate hydrocarbons, carbon and sulfur. After a caustic roasting, the material is leached to obtain a solution containing mainly molybdenum (or tungsten) and vanadium, and a solid containing essentially alumina, cobalt and/or nickel. Molybdenum and vanadium are separated by an ion exchange resin technique. The solid is processed in an arc furnace to separate the alumina. Nickel and cobalt are separated by conventional solvent extraction to obtain pure metal. Alumina is disposed of as an inert slag. The strength of the process lies in the combination of proven technologies applied by companies whose reliability in their respective field is well known. The aspects concerning spent catalyst handling, packaging and transport are also discussed. 13 refs., 2 figs., 2 tabs.

Dearomatization of jet fuel on irradiated platinum-supported catalyst

International Nuclear Information System (INIS)

Mucka, V.; Ostrihonova, A.; Kopernicky, I.; Mikula, O.

1983-01-01

The effect of ionizing radiation ( 60 Co #betta#-rays) on Pt-supported catalyst used for the dearomatization of jet fuel with distillation in the range 395 to 534 K has been studied. Pre-irradiation of the catalyst with doses in the range 10 2 to 5 x 10 4 Gy leads to the partial catalyst activation. Irradiation of the catalyst enhances its resistance to catalyst poisons, particularly to sulphur-compounds, and this is probably the reason for its catalytic activity being approx. 60 to 100% greater than that of un-irradiated catalyst. Optimum conditions for dearomatization on the irradiated catalyst were found and, by means of a rotary three-factorial experiment, it was shown that these lie at lower temperatures and lower pressures than those for un-irradiated catalyst. (author)

Dissolution of Metal Supported Spent Auto Catalysts in Acids

Directory of Open Access Journals (Sweden)

Fornalczyk A.

2016-03-01

Full Text Available Metal supported auto catalysts, have been used in sports and racing cars initially, but nowadays their application systematically increases. In Metal Substrate (supported Converters (MSC, catalytic functions are performed by the Platinum Group Metals (PGM: Pt, Pd, Rh, similarly to the catalysts on ceramic carriers. The contents of these metals make that spent catalytic converters are valuable source of precious metals. All over the world there are many methods for the metals recovery from the ceramic carriers, however, the issue of platinum recovery from metal supported catalysts has not been studied sufficiently yet. The paper presents preliminary results of dissolution of spent automotive catalyst on a metal carrier by means of acids: H2SO4, HCl, HNO3, H3PO4. The main assumption of the research was the dissolution of base metals (Fe, Cr, Al from metallic carrier of catalyst, avoiding dissolution of PGMs. Dissolution was the most effective when concentrated hydrochloric acid, and 2M sulfuric acid (VI was used. It was observed that the dust, remaining after leaching, contained platinum in the level of 0.8% and 0.7%, respectively.

Glycerol valorization: dehydration to acrolein over silica-supported niobia catalysts

NARCIS (Netherlands)

Shiju, N.R.; Brown, D.R.; Wilson, K.; Rothenberg, G.

2010-01-01

The catalytic dehydration of glycerol to acrolein is investigated over silica-supported niobia catalysts in a continuous fixed-bed gas-phase reactor. Various supported niobia catalysts are prepared and characterized using surface analysis and spectroscopic methods (XRD, UV-Vis, XPS, N2 adsorption),

Physico-Chemical and Structural Properties of DeNOx and SO2 Oxidation Catalysts

DEFF Research Database (Denmark)

Masters, Stephen Grenville; Oehlers, Cord; Nielsen, Kurt

1996-01-01

Commercial catalysts for NOx removal and SO2 oxidation and their model systems have been investigated by spectroscopic, thermal, electrochemical and X-ray methods. Structural information on the vanadium complexes and compounds as well as physico-chemical properties for catalyst model systems have...

Iron-57 and iridium-193 Moessbauer spectroscopic studies of supported iron-iridium catalysts

International Nuclear Information System (INIS)

Berry, F.J.; Jobson, S.

1988-01-01

57 Fe and 193 Ir Moessbauer spectroscopy shows that silica- and alumina-supported iron-iridium catalysts formed by calcination in air contain mixtures of small particle iron(III) oxide and iridium(IV) oxide. The iridium dioxide in both supported catalysts is reduced in hydrogen to metallic iridium. The α-Fe 2 O 3 in the silica supported materials is predominantly reduced in hydrogen to an iron-iridium alloy whilst in the alumina-supported catalyst the iron is stabilised by treatment in hydrogen as iron(II). Treatment of a hydrogen-reduced silica-supported iron catalyst in hydrogen and carbon monoxide is accompanied by the formation of iron carbides. Carbide formation is not observed when the iron-iridium catalysts are treated in similar atmospheres. The results from the bimetallic catalysts are discussed in terms of the hydrogenation of associatively adsorbed carbon monoxide and the selectivity of supported iron-iridium catalysts to methanol formation. (orig.)

Analysis of molybdenum, chromium, vanadium and iron by polarographic techniques

International Nuclear Information System (INIS)

Al-Zand, T.K.

1986-01-01

The application of direct current Tast polarograph, differential pulse polarography and phase-selective alternative current Tast polarography to the problem of determining molybdenum, chromium, vanadium and iron in various supporting electrolytes is reported. The effect of the supporting electrolyte on the wave/peak potential and sensitivity of the metal ion have been examined. The polarographic methods were applied for simultaneous determination of chromium (3)/chromium (6), vanadium (4), vanadium (5) and iron (2)/iron (3) in different supporting electrolytes

Potential for preparation of hot gas cleanup sorbents from spent hydroprocessing catalysts

Energy Technology Data Exchange (ETDEWEB)

Furimsky, E.; Biagini, M. [Canada Centre for Mineral and Energy Technology, Ottawa, ON (Canada). Energy Research Labs.

1996-01-01

Three spent-decoked hydroprocessing catalysts and two corresponding fresh catalysts were tested as hot gas clean-up sorbents and compared with the zinc ferrite using a simulated coal gasification gas mixture. The catalysts deposited only by coke exhibited relatively good cleaning efficiency. The catalyst deposited by coke and metals such as vanadium and nickel was less efficient. The useful life of the spent hydroprocessing catalysts may be extended if utilized as hot gas clean-up sorbents. 12 refs., 3 figs., 4 tabs.

Graphene: a promising two-dimensional support for heterogeneous catalysts

Directory of Open Access Journals (Sweden)

Xiaobin eFan

2015-01-01

Full Text Available Graphene has many advantages that make it an attractive two-dimensional (2D support for heterogeneous catalysts. It not only allows the high loading of targeted catalytic species, but also facilitates the mass transfer during the reaction processes. These advantages, along with its unique physical and chemical properties, endow graphene great potential as catalyst support in heterogeneous catalysis.

Novel hybrid materials based on the vanadium oxide nanobelts

Energy Technology Data Exchange (ETDEWEB)

Zabrodina, G.S., E-mail: kudgs@mail.ru [G.A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); Lobachevsky State University, Nizhny Novgorod 603950 (Russian Federation); Makarov, S.G.; Kremlev, K.V. [G.A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); Lobachevsky State University, Nizhny Novgorod 603950 (Russian Federation); Yunin, P.A.; Gusev, S.A. [Institute for Physics of Microstructures Russian Academy of Sciences, Nizhny Novgorod 603087 (Russian Federation); Kaverin, B.S.; Kaverina, L.B. [G.A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); Ketkov, S.Yu. [G.A. Razuvaev Institute of Organometallic Chemistry of Russian Academy of Sciences, Nizhny Novgorod 603950 (Russian Federation); Lobachevsky State University, Nizhny Novgorod 603950 (Russian Federation)

2016-04-15

Graphical abstract: - Highlights: • Flat and curved vanadium oxide nanobelts have been synthesized. • Hybrid material was prepared via decoration of flexible nanobelts with zinc phthalocyanine. • Investigations of the thermal stability, morphologies and structures were carried out. - Abstract: Novel hybrid materials based on zinc phthalocyanine and nanostructured vanadium oxides have attracted extensive attention for the development of academic research and innovative industrial applications such as flexible electronics, optical sensors and heterogeneous catalysts. Vanadium oxides nanobelts were synthesized via a hydrothermal treatment V{sub 2}O{sub 5}·nH{sub 2}O gel with surfactants (TBAB, CTAB) used as structure-directing agents, where CTAB – cetyltrimethylammonium bromide, TBAB – tetrabutylammonium bromide. Hybrid materials were prepared decoration of (CTA){sub 0.33}V{sub 2}O{sub 5} flexible nanobelts with cationic zinc phthalocyanine by the ion-exchange route. Investigations of the thermal stability, morphologies and structures of the (CTA){sub 0.33}V{sub 2}O{sub 5}, (TBA){sub 0.16}V{sub 2}O{sub 5} nanobelts and zinc phthalocyanine exchange product were carried out. The hybrid materials based on the nanostructured vanadium oxide and zinc phthalocyanine were tested as photocatalysts for oxidation of citronellol and 2-mercaptoethanol by dioxygen.

Vanadium oxide monolayer catalysts : The vapor-phase oxidation of methanol

NARCIS (Netherlands)

Roozeboom, Fred; Cordingley, Peter D.; Gellings, P.J.

1981-01-01

The oxidation of methanol over vanadium oxide, unsupported and applied as a monolayer on γ-Al2O3, CeO2, TiO2, and ZrO2, was studied between 100 and 400 °C in a continuous-flow reactor. At temperatures from 150 to about 250 °C two main reactions take place, (a) dehydration of methanol to dimethyl

EXAFS characterization of supported metal catalysts in chemically dynamic environments

International Nuclear Information System (INIS)

Robota, H.J.

1991-01-01

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

Sulfidation of alumina-supported iron and iron-molybdenum oxide catalysts

NARCIS (Netherlands)

Ramselaar, W.L.T.M.; Crajé, M.W.J.; Hadders, R.H.; Gerkema, E.; Beer, de V.H.J.; Kraan, van der A.M.

1990-01-01

The transition of alumina-supported iron and iron-molybdenum catalysts from the oxidic precursor to the sulfided catalysts was systematically studied by means of in-situ Mössbauer spectroscopy at room temperature. This enabled the adjudgement of various sulfidic phases in the sulfided catalysts. The

Practical, economical, and eco-friendly starch-supported palladium catalyst for Suzuki coupling reactions.

Science.gov (United States)

Baran, Talat

2017-06-15

In catalytic systems, the support materials need to be both eco friendly and low cost as well as having high thermal and chemical stability. In this paper, a novel starch supported palladium catalyst, which had these outstanding properties, was designed and its catalytic activity was evaluated in a Suzuki coupling reaction under microwave heating with solvent-free and mild reaction conditions. The starch supported catalyst gave remarkable reaction yields after only 5min as a result of the coupling reaction of the phenyl boronic acid with 23 different substrates, which are bearing aril bromide, iodide, and chloride. The longevity of the catalyst was also investigated, and the catalyst could be reused for 10 runs. The starch supported Pd(II) catalyst yielded remarkable TON (up to 25,000) and TOF (up to 312,500) values by using a simple, fast and eco-friendly method. In addition, the catalytic performance of the catalyst was tested against different commercial palladium catalysts, and the green starch supported catalyst had excellent selectivity. The catalytic tests showed that the novel starch based palladium catalyst proved to be an economical and practical catalyst for the synthesis of biaryl compounds. Copyright © 2017 Elsevier Inc. All rights reserved.

Liquid phase catalytic hydrodebromination of tetrabromobisphenol A on supported Pd catalysts

International Nuclear Information System (INIS)

Wu, Ke; Zheng, Mengjia; Han, Yuxiang; Xu, Zhaoyi; Zheng, Shourong

2016-01-01

Highlights: • Pd catalysts supported on TiO_2, CeO_2, Al_2O_3 and SiO_2 were prepared. • Deposition-precipitation method resulted in positively charged smaller Pd particle. • Complete debromination of tetrabromobisphenol A could be achieved on Pd/TiO_2. • Pd/TiO_2 prepared by the deposition-precipitation method was more active. - Abstract: Tetrabromobisphenol A (TBBPA) is a widely used brominated flame retardant and reductive debromination is an effective method for the abatement of TBBPA pollution. In this study, Pd catalysts supported on TiO_2, CeO_2, Al_2O_3 and SiO_2 were prepared by the impregnation (the resulting catalyst denoted as im-Pd/support), deposition-precipitation (the resulting catalyst denoted as dp-Pd/support), and photo-deposition (the resulting catalyst denoted as pd-Pd/support) methods. The catalysts were characterized by N_2 adsorption-desorption isotherm, X-ray diffraction, transmission electron microscopy, measurement of zeta potential, CO chemisorption, and X-ray photoelectron spectroscopy. The results showed that at an identical Pd loading amount (2.0 wt.%) Pd particle size in dp-Pd/TiO_2 was much smaller than those in im-Pd/TiO_2 and pd-Pd/TiO_2. Pd particle size of the dp-Pd/TiO_2 catalyst increased with Pd loading amount. Additionally, Pd particles in the dp-Pd/TiO_2 catalysts were positively charged due to the strong metal-support interaction, whereas the cationization effect was gradually attenuated with the increase of Pd loading amount. For the liquid phase catalytic hydrodebromination (HDB) of TBBPA, tri-bromobisphenol A (tri-BBPA), di-bromobisphenol A (di-BBPA), and mono-bromobisphenol A (mono-BBPA) were identified as the intermediate products, indicative of a stepwise debromination process. The catalytic HDB of TBBPA followed the Langmuir-Hinshelwood model, reflecting an adsorption enhanced catalysis mechanism. At an identical Pd loading amount, the Pd catalyst supported on TiO_2 exhibited a much higher catalytic activity

Templating Routes to Supported Oxide Catalysts by Design

Energy Technology Data Exchange (ETDEWEB)

Notestein, Justin M. [Northwestern Univ., Evanston, IL (United States)

2016-09-08

The rational design and understanding of supported oxide catalysts requires at least three advancements, in order of increasing complexity: the ability to quantify the number and nature of active sites in a catalytic material, the ability to place external controls on the number and structure of these active sites, and the ability to assemble these active sites so as to carry out more complex functions in tandem. As part of an individual investigator research program that is integrated with the Northwestern University Institute for Catalysis in Energy Processes (ICEP) as of 2015, significant advances were achieved in these three areas. First, phosphonic acids were utilized in the quantitative assessment of the number of active and geometrically-available sites in MO_x-SiO₂ catalysts, including nanocrystalline composites, co-condensed materials, and grafted structures, for M=Ti, Zr, Hf, Nb, and Ta. That work built off progress in understanding supported Fe, Cu, and Co oxide catalysts from chelating and/or multinuclear precursors to maximize surface reactivity. Secondly, significant progress was made in the new area of using thin oxide overcoats containing ‘nanocavities’ from organic templates as a method to control the dispersion and thermal stability of subsequently deposited metal nanoparticles or other catalytic domains. Similar methods were used to control surface reactivity in SiO₂-Al₂O₃ acid catalysts and to control reactant selectivity in Al₂O₃-TiO₂ photocatalysts. Finally, knowledge gained from the first two areas has been combined to synthesize a tandem catalyst for hydrotreating reactions and an orthogonal tandem catalyst system where two subsequent reactions in a reaction network are independently controlled by light and heat. Overall, work carried out under this project significantly advanced the knowledge of synthesis-structure-function relationships in supported

{alpha}-Al{sub 2}O{sub 3} catalyst supports for synthesis gas production: influence of different alumina bonding agents on support and catalyst properties

Energy Technology Data Exchange (ETDEWEB)

Marturano, M. [Centro de Investigacion y Desarrollo en Procesos Cataliticos, La Plata (Argentina); Aglietti, E.F. [Centro de Tecnologia de Recursos Minerales y Ceramica (CETMIC), Gonnet (Argentina); Ferretti, O. [Centro de Investigacion y Desarrollo en Procesos Cataliticos, La Plata (Argentina)]|[Univ. Nacional de La Plata, Dept. de Ingenieria Quimica de la Facultad de Ingenieria, La Plata (Argentina)

1997-02-01

Aluminas are widely used as catalytic supports in chemical reactions. Reforming reactions to obtain synthesis gas requires good mechanical strength and low sintering behaviour. In this work, the influence of bentonite, aluminium phosphate and alumina gel as binder agents of a calcined {alpha}-Al{sub 2}O{sub 3} are analyzed with respect to support and catalytic properties. The {alpha}-Al{sub 2}O{sub 3} supports, calcined at 1300 C, are then impregnated with solutions of Ni and Al inorganic salts to obtain the catalysts and are finally tested in the reforming reaction of methane to synthesis gas at 500-900 C. Supports and catalysts are characterized by XRD, SEM, N{sub 2} adsorption, mechanical strength test and other techniques. Mechanical strength depends on the type and quantity of binder material used during support preparation. The influence of the support on the performance of the resulting catalyst is evidenced by means of catalytic tests. (orig.) 8 refs.

TiO2 nanotubes supported NiW hydrodesulphurization catalysts: Characterization and activity

International Nuclear Information System (INIS)

Palcheva, R.; Dimitrov, L.; Tyuliev, G.; Spojakina, A.; Jiratova, K.

2013-01-01

Highlights: ► NiW catalysts supported on TiO 2 nanotubes, titania and alumina. ► The best results are obtained with NiW/TiO 2 nanotubes in hydrodesulfurization (HDS) of thiophene. ► Active phase is Ni-WO x S y . ► Electronic promotion of W by Ti. - Abstract: High surface area TiO 2 nanotubes (Ti-NT) synthesized by alkali hydrothermal method were used as a support for NiW hydrodesulphurization catalyst. Nickel salt of 12-tungstophosphoric acid – Ni 3/2 PW 12 O 40 was applied as oxide precursor of the active components. The catalyst was characterized by S BET , XRD, UV–vis DRS, Raman spectroscopy, XPS, TPR and HRTEM. The results obtained were compared with those for the NiW catalysts prepared over high surface area titania and alumina supports. A polytungstate phase evidenced by Raman spectroscopy was observed indicating the destruction of the initial heteropolyanion. The catalytic experiments revealed two times higher thiophene conversion on NiW catalyst supported on Ti-NT than those of catalysts supported on alumina and titania. Increased HDS activity of the NiW catalyst supported on Ti-NT could be related to a higher amount of W oxysulfide entities interacting with Ni sulfide particles as consequence of the electronic effects of the Ti-NT observed with XPS analysis.

Nanosheet Supported Single-Metal Atom Bifunctional Catalyst for Overall Water Splitting.

Science.gov (United States)

Ling, Chongyi; Shi, Li; Ouyang, Yixin; Zeng, Xiao Cheng; Wang, Jinlan

2017-08-09

Nanosheet supported single-atom catalysts (SACs) can make full use of metal atoms and yet entail high selectivity and activity, and bifunctional catalysts can enable higher performance while lowering the cost than two separate unifunctional catalysts. Supported single-atom bifunctional catalysts are therefore of great economic interest and scientific importance. Here, on the basis of first-principles computations, we report a design of the first single-atom bifunctional eletrocatalyst, namely, isolated nickel atom supported on β 12 boron monolayer (Ni 1 /β 12 -BM), to achieve overall water splitting. This nanosheet supported SAC exhibits remarkable electrocatalytic performance with the computed overpotential for oxygen/hydrogen evolution reaction being just 0.40/0.06 V. The ab initio molecular dynamics simulation shows that the SAC can survive up to 800 K elevated temperature, while enacting a high energy barrier of 1.68 eV to prevent isolated Ni atoms from clustering. A viable experimental route for the synthesis of Ni 1 /β 12 -BM SAC is demonstrated from computer simulation. The desired nanosheet supported single-atom bifunctional catalysts not only show great potential for achieving overall water splitting but also offer cost-effective opportunities for advancing clean energy technology.

Intercalation compounds of vanadium pentoxide hydrated with metalporphyrins and lanthanide ions

International Nuclear Information System (INIS)

Oliveira, Herenilton Paulino

1994-01-01

The lamellar structure of the vanadium pentoxide matrix allows the intercalation of organic molecules, ions and conductor polymers. It is important to emphasize that the vanadium oxide matrix is an intrinsic semiconductor and presents electrochromic properties. In the beginning of this work the method of synthesis and the electrochemical and electrochromic properties were extensively explored. The effect of alkaline metal and lanthanide ions on the structure of vanadium oxide matrix was studied by X-ray and infrared spectroscopy. Moreover, the influence of those ions in the electrochemical, spectro electrochemical and magnetic properties were studied. Finally, some intercalation compounds containing porphyrins were prepared and characterized by elemental analysis, X-ray diffraction, and electronic, vibrational, Moessbauer and X-ray fluorescence spectroscopy. The electrochemical and spectro electrochemical properties were investigated. And the performance of an iron porphyrin based intercalation compound as catalyst for molecular oxygen reduction was evaluated using the rotating ring-disc electrode technique. (author)

Gas-phase Dehydration of Glycerol over Supported Silicotungstic Acids Catalysts

International Nuclear Information System (INIS)

Kim, Yong Tae; Park, Eun Duck; Jung, Kwang Deog

2010-01-01

The gas-phase dehydration of glycerol to acrolein was carried out over 10 wt % HSiW catalysts supported on different supports, viz. γ-Al 2 O 3 , SiO 2 -Al 2 O 3 , TiO 2 , ZrO 2 , SiO 2 , AC, CeO 2 and MgO. The same reaction was also conducted over each support without HSiW for comparison. Several characterization techniques, N 2 -physisorption, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), the temperature-programmed desorption of ammonia (NH 3 - TPD), temperature-programmed oxidation (TPO) with mass spectroscopy and CHNS analysis were employed to characterize the catalysts. The glycerol conversion generally increased with increasing amount of acid sites. Ceria showed the highest 1-hydroxyacetone selectivity at 315 .deg. C among the various metal oxides. The supported HSiW catalyst showed superior catalytic activity to that of the corresponding support. Among the supported HSiW catalysts, HSiW/ZrO 2 and HSiW/SiO 2 -Al 2 O 3 showed the highest acrolein selectivity. In the case of HSiW/ZrO 2 , the initial catalytic activity was recovered after the removal of the accumulated carbon species at 550 .deg. C in the presence of oxygen

Electroreduction of oxygen on carbon-supported gold catalysts

International Nuclear Information System (INIS)

Erikson, Heiki; Juermann, Gea; Sarapuu, Ave; Potter, Robert J.; Tammeveski, Kaido

2009-01-01

The electrochemical reduction of oxygen was studied on Au/C catalysts (20 and 30 wt%) in 0.5 M H 2 SO 4 and 0.1 M KOH solutions using the rotating disk electrode (RDE) method. The thickness of the Au/C-Nafion layers was varied between 1.5 and 10 μm. The specific activity of Au was independent of catalyst loading in both solutions, indicating that the transport of reactants through the catalyst layer does not limit the process of oxygen reduction under these conditions. The mass activity of 20 wt% Au/C catalysts was higher due to smaller particle size. The number of electrons involved in the reaction and the Tafel slopes were found; the values of these parameters are similar to that of bulk polycrystalline gold and indicate that the mechanism of O 2 reduction is not affected by carbon support or the catalyst configuration.

Liquid phase catalytic hydrodebromination of tetrabromobisphenol A on supported Pd catalysts

Energy Technology Data Exchange (ETDEWEB)

Wu, Ke [State Key Laboratory of Pollution Control and Resource Reuse, Jiangsu Key Laboratory of Vehicle Emissions Control, School of the Environment, Nanjing University, Nanjing 210023 (China); Zheng, Mengjia [Kuang Yaming Honors School, Nanjing University, Nanjing 210023 (China); Han, Yuxiang [State Key Laboratory of Pollution Control and Resource Reuse, Jiangsu Key Laboratory of Vehicle Emissions Control, School of the Environment, Nanjing University, Nanjing 210023 (China); Xu, Zhaoyi, E-mail: zhaoyixu@nju.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, Jiangsu Key Laboratory of Vehicle Emissions Control, School of the Environment, Nanjing University, Nanjing 210023 (China); Zheng, Shourong [State Key Laboratory of Pollution Control and Resource Reuse, Jiangsu Key Laboratory of Vehicle Emissions Control, School of the Environment, Nanjing University, Nanjing 210023 (China)

2016-07-15

Highlights: • Pd catalysts supported on TiO{sub 2}, CeO{sub 2}, Al{sub 2}O{sub 3} and SiO{sub 2} were prepared. • Deposition-precipitation method resulted in positively charged smaller Pd particle. • Complete debromination of tetrabromobisphenol A could be achieved on Pd/TiO{sub 2}. • Pd/TiO{sub 2} prepared by the deposition-precipitation method was more active. - Abstract: Tetrabromobisphenol A (TBBPA) is a widely used brominated flame retardant and reductive debromination is an effective method for the abatement of TBBPA pollution. In this study, Pd catalysts supported on TiO{sub 2}, CeO{sub 2}, Al{sub 2}O{sub 3} and SiO{sub 2} were prepared by the impregnation (the resulting catalyst denoted as im-Pd/support), deposition-precipitation (the resulting catalyst denoted as dp-Pd/support), and photo-deposition (the resulting catalyst denoted as pd-Pd/support) methods. The catalysts were characterized by N{sub 2} adsorption-desorption isotherm, X-ray diffraction, transmission electron microscopy, measurement of zeta potential, CO chemisorption, and X-ray photoelectron spectroscopy. The results showed that at an identical Pd loading amount (2.0 wt.%) Pd particle size in dp-Pd/TiO{sub 2} was much smaller than those in im-Pd/TiO{sub 2} and pd-Pd/TiO{sub 2}. Pd particle size of the dp-Pd/TiO{sub 2} catalyst increased with Pd loading amount. Additionally, Pd particles in the dp-Pd/TiO{sub 2} catalysts were positively charged due to the strong metal-support interaction, whereas the cationization effect was gradually attenuated with the increase of Pd loading amount. For the liquid phase catalytic hydrodebromination (HDB) of TBBPA, tri-bromobisphenol A (tri-BBPA), di-bromobisphenol A (di-BBPA), and mono-bromobisphenol A (mono-BBPA) were identified as the intermediate products, indicative of a stepwise debromination process. The catalytic HDB of TBBPA followed the Langmuir-Hinshelwood model, reflecting an adsorption enhanced catalysis mechanism. At an identical Pd

Wire gauze and cordierite supported noble metal catalysts for passive autocatalytic recombiner

International Nuclear Information System (INIS)

Sanap, Kiran K.; Varma, S.; Waghmode, S.B.; Bharadwaj, S.R.

2015-01-01

Highlights: • Synthesis by electroless deposition method and chemical reduction route. • Particle size of 0.1–0.5 μm & 3.5–5 nm for Pt–Pd/Wg & Pt–Pd/Cord catalysts. • Active for H_2 and O_2 reaction with initial H_2 concentration of 1.5 to 7% in air. • Active in presence of different contaminants like CO_2, CH_4, CO & relative humidity. • Enhanced resistance of Pt–Pd/Cord catalyst towards the poisoning of CO. - Abstract: Hydrogen released in nuclear reactor containment under severe accident scenario poses a threat to containment and hence needs to be regulated by catalytic recombination. Mixed noble metal catalysts with platinum–palladium supported on stainless steel wire gauze and cordierite support have been developed for this purpose. The developed catalysts have been found to be highly efficient for removal of hydrogen concentration in the range of 1.5 to 7.0% v/v in air. Though both the catalysts exhibit similar kinetics for lower hydrogen concentration, cordierite supported catalysts exhibits better kinetic rate at higher hydrogen concentration. The performances of these catalysts in presence of various probable catalytic poison like carbon monoxide and catalytic inhibitors like moisture, carbon dioxide, and hydrocarbons provide data for use of these catalysts under the actual scenario. Compared to stainless steel wire gauze supported catalyst, the cordierite based catalyst are found to exhibit enhanced resistance towards carbon monoxide and limited temperature rise for safer application at higher hydrogen concentrations.

Solution XAS Analysis for Exploring the Active Species in Homogeneous Vanadium Complex Catalysis

Science.gov (United States)

Nomura, Kotohiro; Mitsudome, Takato; Tsutsumi, Ken; Yamazoe, Seiji

2018-06-01

Selected examples in V K-edge X-ray Absorption Near Edge Structure (XANES) analysis of a series of vanadium complexes containing imido ligands (possessing metal-nitrogen double bond) in toluene solution have been introduced, and their pre-edge and the edge were affected by their structures and nature of ligands. Selected results in exploring the oxidation states of the active species in ethylene dimerization/polymerization using homogeneous vanadium catalysts [consisting of (imido)vanadium(V) complexes and Al cocatalysts] by X-ray absorption spectroscopy (XAS) analyses have been introduced. It has been demonstrated that the method should provide more clear information concerning the active species in situ, especially by combination with the other methods (NMR and ESR spectra, X-ray crystallographic analysis, and reaction chemistry), and should be powerful tool for study of catalysis mechanism as well as for the structural analysis in solution.

Fuel cell testing of Pt–Ru catalysts supported on differently prepared and pretreated carbon nanotubes

International Nuclear Information System (INIS)

Tokarz, Wojciech; Lota, Grzegorz; Frackowiak, Elzbieta; Czerwiński, Andrzej; Piela, Piotr

2013-01-01

Proton-exchange membrane fuel cell (PEMFC) testing of Pt–Ru catalysts supported on differently prepared multiwall carbon nanotube (MCNT) supports was performed to elucidate the influence of the different supports on the operating characteristics of the catalysts under real direct methanol fuel cell (DMFC) anode and H 2 -PEMFC anode conditions. The MCNTs were either thin, entangled or thick, disentangled. Pretreatment of the MCNTs was also done and it was either high-temperature KOH etching or annealing (graphitization). The performance of the catalysts was compared against the performance of a commercial Pt–Ru catalyst supported on a high-surface-area carbon black. Among the different MCNT supports, the graphitized, entangled support offered the best performance in all tests, which was equal to the performance of the commercial catalyst, despite the MCNT catalyst layer was ca. 2.2 times thicker than the carbon black catalyst layer. Even for an MCNT catalyst layer, which was almost 7 times thicker than the carbon black catalyst layer, the transport limitations were not prohibitive. This confirmed the expected potential of nanotube supports for providing superior reactant transport properties of the PEMFC catalyst layers

Determination of vanadium in Syrian commercial and raffinate phosphoric acid

International Nuclear Information System (INIS)

Al-Merey, R.

2002-04-01

This study presents two methods for vanadium determination in Syrian commercial phosphoric acid. The vanadium (V) in the oxidized commercial phosphoric acid by ammonium persulfate solution is extracted from 5-M hydrochloride acid medium using N-benzoyl-N-phenyl hydroxyl amine (BPHA) in chloroform as an extracting solution. The first method, the extract vanadium as VOL 2 Cl is changed to V 2 O 3 L 4 complex by the addition of benzimidazole in 1-butanol to the violet organic layer. The absorbance is then measured at 440 nm (the molar absorptivity was found to be 3865 M -1 cm -1 ), where Beer law is applicable up to 36-μg ml -1 . the accuracy, precision and detection limit were found to be 3.7%, 77 ppb and 37 ppb, respectively. the second method, the organic layer is heated to evaporate chloroform, the residue is digested using 20% ammonium persulfate and 2-M sulfuric acid solutions. The vanadium concentration is measured spectrophotometrically by oxidizing gallic acid with persulfate (S 2 O 8 2- ) anion in phosphoric acid medium, where the vanadium (V) acts as a catalyst in the oxidation reaction. This method has a high sensitivity (∼10 -12 ) with accuracy and precision 5% and 0.621 ppb, respectively. Also Beer law at λ m ax=415 nm (ε=∼2 x 10 6 M -1 ) is applicable in the range 2.58-33.3 ppb. (author)

Palladium catalysts deposited on silica materials: Comparison of catalysts based on mesoporous and amorphous supports in Heck reaction

Czech Academy of Sciences Publication Activity Database

Demel, J.; Čejka, Jiří; Štěpnička, P.

2010-01-01

Roč. 329, 1-2 (2010), s. 13-20 ISSN 1381-1169 R&D Projects: GA ČR GA104/09/0561 Institutional research plan: CEZ:AV0Z40400503 Keywords : heterogeneous catalysts * immobolized catalysts * supported catalysts Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.872, year: 2010

Partial Oxidation of n-Butane over a Sol-Gel Prepared Vanadium Phosphorous Oxide

Directory of Open Access Journals (Sweden)

Juan M. Salazar

2013-01-01

Full Text Available Vanadium phosphorous oxide (VPO is traditionally manufactured from solid vanadium oxides by synthesizing VOHPO4∙0.5H2O (the precursor followed by in situ activation to produce (VO2P2O7 (the active phase. This paper discusses an alternative synthesis method based on sol-gel techniques. Vanadium (V triisopropoxide oxide was reacted with ortho-phosphoric acid in an aprotic solvent. The products were dried at high pressure in an autoclave with a controlled excess of solvent. This procedure produced a gel of VOPO4 with interlayer entrapped molecules. The surface area of the obtained materials was between 50 and 120 m2/g. Alcohol produced by the alkoxide hydrolysis reduced the vanadium during the drying step, thus VOPO4 was converted to the precursor. This procedure yielded non-agglomerated platelets, which were dehydrated and evaluated in a butane-air mixture. Catalysts were significantly more selective than the traditionally prepared materials with similar intrinsic activity. It is suggested that the small crystallite size obtained increased their selectivity towards maleic anhydride.

Carbon a support for sulfide catalysts

NARCIS (Netherlands)

Vissers, J.P.R.; Lensing, T.J.; Mercx, F.P.M.; Beer, de V.H.J.; Prins, R.

1983-01-01

Two types of carbon materials, carbon black composite and carbon covered alumina, were studied for-their use as support for sulfide catalysts. The following parameters were varied: type of carbon black, carbon coverage of the alumina and carbon pretreatment. Pore size distributions were determined

Use of Biomass as a Sustainable and Green Fuel with Alkali-Resistant DeNOx Catalysts based on Sulfated or Tungstated Zirconia

DEFF Research Database (Denmark)

Due-Hansen, Johannes; Fehrmann, Rasmus; Christensen, Claus H.

poisons is the use of supports with highly acidic properties, which would interact stronger with potassium than the vanadium species. Among those, sulfated and tungstated zirconica appears very attractive, since their surface acidity can be tuned in a wide range by varying the preparation procedure, WOX......, sulfated, and tungstated zirconia were prepared and tested. The influence of potassium additives on the acidity and activity was studied and the results were compared with traditional V2O5-WO3/TiO2 catalyst. Resistance of the catalysts towards poisoning with potassium was found to depend dramatically...... on the crystallinity and surface acidity of the support used. Better resistance of the samples based on sulfated and tungstated zirconia seems to be connected with the fact that a significant part of the potassium on the surface of the catalyst preferentially interact with strong acid sites of the support thus...

Silica-supported Preyssler Nanoparticles as New Catalysts in the ...

African Journals Online (AJOL)

A new and efficient method for the preparation of 4(3H)-quinazolinones from the condensation of anthranilic acid, orthoester and substituted anilines, in the presence of catalytic amounts of silica-supported Preyssler nanoparticles is reported. The catalyst performs very well in comparison with other catalysts reported before.

Determination of catalyst residues in hydrocarbon fuels by instrumental neutron activation analysis

International Nuclear Information System (INIS)

Burgess, D.D.

1982-01-01

A procedure has been developed for the determination of entrained catalytic cracking catalyst in hydrocarbon fuels. Aluminium is measured by instrumental neutron activation analysis and the amount of catalyst present is calculated from the amount of aluminium found and the known composition of the catalyst. Entrained catalyst may be determined at levels above 3 ppm with a precision of +-2%-25% according to sample composition. Only simple procedures are required. Vanadium may reduce sensitivity by dead time and pulse pile-up. No other interferences were observed. (author)

Graphitized Carbon: A Promising Stable Cathode Catalyst Support Material for Long Term PEMFC Applications.

Science.gov (United States)

Mohanta, Paritosh Kumar; Regnet, Fabian; Jörissen, Ludwig

2018-05-28

Stability of cathode catalyst support material is one of the big challenges of polymer electrolyte membrane fuel cells (PEMFC) for long term applications. Traditional carbon black (CB) supports are not stable enough to prevent oxidation to CO₂ under fuel cell operating conditions. The feasibility of a graphitized carbon (GC) as a cathode catalyst support for low temperature PEMFC is investigated herein. GC and CB supported Pt electrocatalysts were prepared via an already developed polyol process. The physical characterization of the prepared catalysts was performed using transmission electron microscope (TEM), X-ray Powder Diffraction (XRD) and inductively coupled plasma optical emission spectrometry (ICP-OES) analysis, and their electrochemical characterizations were conducted via cyclic voltammetry(CV), rotating disk electrode (RDE) and potential cycling, and eventually, the catalysts were processed using membrane electrode assemblies (MEA) for single cell performance tests. Electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SEM) have been used as MEA diagonostic tools. GC showed superior stability over CB in acid electrolyte under potential conditions. Single cell MEA performance of the GC-supported catalyst is comparable with the CB-supported catalyst. A correlation of MEA performance of the supported catalysts of different Brunauer⁻Emmett⁻Teller (BET) surface areas with the ionomer content was also established. GC was identified as a promising candidate for catalyst support in terms of both of the stability and the performance of fuel cell.

Attrition resistant gamma-alumina catalyst support

Science.gov (United States)

Singleton, Alan H.; Oukaci, Rachid; Goodwin, James G.

2006-03-14

A .gamma.-alumina catalyst support having improved attrition resistance produced by a method comprising the steps of treating a particulate .gamma.-alumina material with an acidic aqueous solution comprising water and nitric acid and then, prior to adding any catalytic material thereto, calcining the treated .gamma.-alumina.

Graphene supported heterogeneous catalysts for Li–O{sub 2} batteries

Energy Technology Data Exchange (ETDEWEB)

Alaf, M., E-mail: mirac.alaf@bilecik.edu.tr [Bilecik Seyh Edebali University, Engineering Faculty, Department of Metallurgy and Materials Engineering, Gulumbe Campus, Bilecik 11210 (Turkey); Tocoglu, U.; Kartal, M.; Akbulut, H. [Sakarya University, Engineering Faculty, Department of Metallurgy and Materials Engineering, Esentepe Campus, Sakarya 54187 (Turkey)

2016-09-01

Graphical abstract: - Highlights: • Free-standing and flexible electrodes were prepared for Li–air batteries. • α-MnO{sub 2} nanorods, Pt nanoparticles and graphene were used. • α-MnO{sub 2} and Pt catalyst improved OER/ORR kinetics. - Abstract: In this study production and characterization of free-standing and flexible (i) graphene, (ii) α-MnO{sub 2}/graphene, (iii) Pt/graphene (iv) α-MnO{sub 2}/Pt/graphene composite cathodes for Li–air batteries were reported. Graphene supported heterogeneous catalysts were produced by a facile method. In order to prevent aggregation of graphene sheets and increase not only interlayer distance but also surface area, a trace amount multi-wall carbon nano tube (MWCNT) was introduced to the composite structure. The obtained composite catalysts were characterized by SEM, X-ray diffraction, N{sub 2} adsorption–desorption analyze and Raman spectroscopy. The electrochemical characterization tests including galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS) measurement of catalyst were carried out by using an ECC-Air test cell. These highly active graphene supported heterogeneous composite catalysts provide competitive properties relative to other catalyst materials for Li–air batteries.

THE THEORY OF DEVELOPMENT OF SUPPORTED METAL-COMPLEX CATALYSTS

Directory of Open Access Journals (Sweden)

T. L. Rakitskaya

2015-06-01

Full Text Available Some results of the investigations for the purpose of development of supported metal-complex catalysts for phosphine and carbon monoxide oxidation as well as for ozone decomposition are summarized. The activity of such catalysts has been found to depend not only on a nature of a central atom and ligands but also on a nature of supports. The theoretical model explaining mechanisms of surface complex formation taking into account the influence of physicochemical and structural-adsorption properties of the supports (SiO2, Al2O3, carbon materials, zeolites, dispersed silicas, lamellar aluminosilicates, etc. has been proposed. For quantitative description of the support effect, such a thermodynamic parameter as the adsorbed water activity assignable with the help of water vapor adsorption isotherms has been introduced. Successive stability constants of the surface metal complexes have been calculated by the kinetic method and, hence, compositions and partial catalytic activity of the latter have been determined. Taking into account the competitive adsorption of metal ions on the supports, some schemes of formation of surface bimetallic complexes have been suggested. The compositions of the supported metal-complex catalysts have been optimized to meet requirements of their use in respirators and plants for air purification from foregoing gaseous toxicants.

Synthesis and characterization of platinum supported on alumina doped with cerium catalyst

International Nuclear Information System (INIS)

Yusof Abdullah; Abd Fatah Awang Mat; Mohd Ali Sufi; Sarimah Mahat; Razali Kassim; Nurhaslinda Abdullah.

1996-03-01

The synthesis and characterization of gamma-alumina doped with cerium as platinum support for the automobile exhaust catalyst are described. Platinum/alumina/ceria catalyst were prepared by impregnation of hexachloroplatinic acid and sintered at 500 degree Celsius to obtain metal dispersions of 1.0 wt%. Catalyst distribution inside the powder and the effects of the addition of cerium to alumina were analyzed by the scanning electron microscopy (SEM) and x-ray fluorescence spectroscopy (XRF). The results showed that the alumina - supported catalysts contained well dispersion of the noble metal

Effect of Co addition on the performance and structure of V/ZrCe catalyst for simultaneous removal of NO and Hg0 in simulated flue gas

Science.gov (United States)

Zhao, Lingkui; Li, Caiting; Du, Xueyu; Zeng, Guangming; Gao, Lei; Zhai, Yunbo; Wang, Teng; Zhang, Junyi

2018-04-01

The effect of CoOx addition on the performance and structure of V2O5/ZrO2-CeO2 catalyst for simultaneous removal of NO and Hg0 in simulated flue gas was investigated by various methods including SEM, BET, XRD, XPS, H2-TPR and FT-IR. It was found that the introduction of CoOx not only greatly enhanced the redox properties of catalysts, but also increased the catalytic performance for simultaneous removal of NO and Hg0. The CoOx-modified V2O5/ZrO2-CeO2 catalyst displayed excellent catalytic activity for NO conversion (89.6%) and Hg0 oxidation (88.9%) at 250 °C under SCR atmosphere. The synergistic effect among vanadium, cobalt, and the ZrCe support could induce oxygen vacancies formation and promote oxygen mobility via charge transfer. Besides, CoOx could assist vanadium species in rapidly changing the valence by the redox cycle of V5+ + Co2+ ↔ V4+ + Co3+. All the above features contribute to the excellent catalytic performance through CoOx addition.

Synthesis and characterization of MCM-41-supported nano zirconia catalysts

Directory of Open Access Journals (Sweden)

Mohamed S. Abdel Salam

2015-03-01

Full Text Available Series of MCM-41 supported sulfated Zirconia (SZ catalysts with different loadings (2.5–7.5% wt. were prepared using direct impregnation method. The acquired solid catalysts were characterized structurally and chemically using X-RD, HRTEM, BET, FT-IR, Raman spectroscopy and TPD analysis. The acidity of the solid catalysts was investigated through cumene cracking and isopropanol dehydration at different temperatures. As the SZ loading increases, the surface acidity of the mesoporous catalysts was enhanced, this was reflected by the higher catalytic activity toward cumene cracking and isopropanol dehydration.

Vanadium Bioleaching Behavior by Acidithiobacillus ferrooxidans from a Vanadium-Bearing Shale

Directory of Open Access Journals (Sweden)

Dunpei Wei

2018-01-01

Full Text Available This study investigated bioleaching behavior of vanadium from a vanadium-bearing shale using Acidithiobacillus ferrooxidans (A. ferrooxidans. Results showed a maximum recovery of 62% vanadium in 1.2-day bioleaching, which was 22.45% higher than the controls. Then, the vanadium leaching efficiency decreased significantly, only 24% of that was obtained on the tenth day. The vanadium extraction in 1.2 days was mainly attributed to the dissolution of vanadium in free oxides of shale. Fe3+ produced by A. ferrooxidans promoted the dissolution process. X-ray diffraction (XRD patterns of the leached residues confirmed the generation of jarosite. SEM-EDS analysis of the residues indicated that jarosite adsorbed on the shale and inhibited the further dissolution of vanadium. The relevance of V, Fe, S, O was quite good in the energy disperse X-ray spectrometry (EDS element mapping of jarosite, and acid-washing of the jarosite resulted in 31.6% of the vanadium in the precipitates desorption, indicating that the decrease of vanadium leaching efficiency in bioleaching process was caused by both adsorption and co-precipitation with jarosite.

Synthesis and properties of catalysts prepared from silicomolybdovanadium heteropoly acid

International Nuclear Information System (INIS)

Chumachenko, N.N.; Tarasova, D.V.; Nikoro, T.A.; Yaroslavtseva, I.V.

1984-01-01

Catalytic properties of samples prepared of silicomolybdovanadium heteropoly acid (HPA) have been investigated. The massive catalyst is shown to be comparatively low effective in the reaction of acrolein oxidation to acrylic acid. Impregnation of coarse-dispersed silica gel by the HPA solution results in the formation of active and selective catalyst, whereas low-active catalyst of deep oxidation is formed on the base of high-dispersed silica gel. The obtained data are explained by the formation and stabilization of different forms of vanadium- and molybdenum-containing compounds on the carrier surface

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

Directory of Open Access Journals (Sweden)

Atikah Kadri

2015-06-01

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

Graphitic Carbon Nitride as a Catalyst Support in Fuel Cells and Electrolyzers

International Nuclear Information System (INIS)

Mansor, Noramalina; Miller, Thomas S.; Dedigama, Ishanka; Jorge, Ana Belen; Jia, Jingjing; Brázdová, Veronika; Mattevi, Cecilia; Gibbs, Chris; Hodgson, David; Shearing, Paul R.; Howard, Christopher A.; Corà, Furio; Shaffer, Milo; Brett, Daniel J.L.

2016-01-01

Highlights: • Graphitic carbon nitride (gCN) describes many materials with different structures. • gCNs can exhibit excellent mechanical, chemical and thermal resistance. • A major obstacle for pure gCN catalyst supports is limited electronic conductivity. • Composite/Hybrid gCN structures show excellent performance as catalyst supports. • gCNs have great potential for use in fuel calls and water electrolyzers. - Abstract: Electrochemical power sources, such as polymer electrolyte membrane fuel cells (PEMFCs), require the use of precious metal catalysts which are deposited as nanoparticles onto supports in order to minimize their mass loading and therefore cost. State-of-the-art/commercial supports are based on forms of carbon black. However, carbon supports present disadvantages including corrosion in the operating fuel cell environment and loss of catalyst activity. Here we review recent work examining the potential of different varieties of graphitic carbon nitride (gCN) as catalyst supports, highlighting their likely benefits, as well as the challenges associated with their implementation. The performance of gCN and hybrid gCN-carbon materials as PEMFC electrodes is discussed, as well as their potential for use in alkaline systems and water electrolyzers. We illustrate the discussion with examples taken from our own recent studies.

Petroleum residue upgrading with dispersed catalysts. Part 1. Catalysts activity and selectivity

Energy Technology Data Exchange (ETDEWEB)

Panariti, N.; Del Bianco, A.; Del Piero, G. [ENITECNOLOGIE S.p.A, Via Maritano 26, 20097 San Donato Mil. (Italy); Marchionna, M. [SNAMPROGETTI S.p.A, Via Maritano 26, 20097 San Donato Mil. (Italy)

2000-12-04

The results of a study aimed at the identification of the relevant chemical aspects involved in the process of upgrading heavy feedstocks in the presence of dispersed catalysts are discussed. The catalytic activity of different compounds was compared in terms of products yields and quality. Moreover, a detailed and systematic characterization of the catalysts recovered at the end of the reactions was achieved. The experimental work provided quite a large set of data, allowing to investigate the factors that may affect catalyst activity (precursor solubility, rate of activation, degree of dispersion, presence of promoters, etc.). The results of this study demonstrate that the best performances are obtained by the microcrystalline molybdenite generated in situ by oil-soluble precursors. The nature of the organic ligand does not play a very relevant role in influencing the hydrogenation activity. The presence of phosphorus, however, significantly enhances hydrodemetallation, at least in terms of vanadium removal. Bimetallic precursors show a slight synergistic effect towards the hydrodesulfurization reaction. Microsized powdered catalyst precursors have a much lower catalytic activity compared to the oil-soluble ones.

Hydrogenation of carbon monoxide on WO/sub 3/-Supported ruthenium catalysts

Energy Technology Data Exchange (ETDEWEB)

Yoshinari, Tomohiro; Suganuma, Fujio; Sera, Chikara

1988-01-01

In this study, a WO/sub 3/-supported catalyst was prepared to conduct hydrogenation of CO for examining the product distribution and composition of hydrocarbons, using a gamma-alumina-supported catalyst for comparison. These catalysts were used under pressure to conduct a distributive reaction and the desorbing behavior of CO or H/sub 2/ at elevated temperature was measured to examine the influence of the type of carrier or the method of preparation on the activity and the distribution of products formed. The WO/sub 3/-supported catalyst gave a carbon chain length distribution that did not comply with the rule of Schulz-Flory, giving a composition richer in the isomers. Carbon number distribution is affected by Ru-dispersion, and the selectivity of isomers depends on the acidity of the carrier. Formed products distribution of the WO/sub 3/-supported reaction is attributable to the secondary reaction, which relates to the acidic point of the carrier, of the primary product formed on the metal. (7 figs, 4 tabs, 18 refs)

Effects of Cu over Pd based catalysts supported on silica or niobia

Directory of Open Access Journals (Sweden)

Roma M.N.S.C.

2000-01-01

Full Text Available Palladium and palladium-copper catalysts supported on silica and niobia were characterized by H2 chemisorption and H2-O2 titration. Systems over silica were also analyzed by transmission electron microscopy and EXAFS. The metallic dispersion decreased from 20% to 7% when the content of Pd was increased from 0.5wt.-% to 3wt.-% in monometallic catalysts. The addition of 3 wt.-% Cu to obtain Pd-Cu catalysts caused a remarkable capacity loss of hydrogen chemisorption. TPR analysis suggested an interaction between the two metals and EXAFS characterization of the catalyst supported on silica confirmed the formation of Pd-Cu alloy. Pd/Nb2O5 catalysts showed turnover numbers higher than those obtained with the Pd/SiO2 systems in the cyclohexane dehydrogenation. However, the bimetallic catalysts showed very low turnover numbers.

Investigation of altenative carbon materials for fuel-cell catalyst support

DEFF Research Database (Denmark)

Larsen, Mikkel Juul

In order to ensure high utilization of the catalyst material in a polymer electrolyte membrane fuel cell (PEMFC) it is usually fixed in the form of nanoparticles on a supporting material. The catalyst is platinum or a platinum alloy, and the commonly used support is carbon black (CB). Although...... structured carbon forms such as graphitized CBs, carbon nanotubes (CNTs), and carbon nanofibres (CNFs). This thesis concerns the investigation of an array of different materials which may prospec-tively replace the conventional materials used in the catalyst. The study comprised 13 carbon samples which...... nanotubes (GMWCNTs), and graphitized carbon nanofibre (CNF), while the Pt/C samples were platinized samples of some of the CNTs and CNFs (Pt/FWCNT, Pt/GMWCNT, and Pt/CNF, respectively) as well as two commercial Pt/CB reference catalysts. Comparative analyses have been performed in order to be able to assess...

Stability of V₂O₅ Supported on Titania in the Presence of Water, Bulk Oxygen Vacancies, and Adsorbed Oxygen Atoms

DEFF Research Database (Denmark)

Kristoffersen, Henrik Høgh; Neilson, Hunter L.; Buratto, Steven K.

2017-01-01

). In the case of oxidative dehydrogenation of alkanes and methanol, the reaction produces water, oxygen vacancies, and hydrogen atoms bound to the surface. For this article we use density functional theory to examine how the presence of these species on the surface affects a V2O5 cluster, which we assume......A catalyst consisting of vanadium oxide submonolayers supported on rutile titanium dioxide is used for a variety of reactions. One important question is the difference between the activity of monomeric clusters (having one vanadium atom) and polymeric clusters (having more than one vanadium atom...

Researches on vanadium and its compounds; Recherches sur le Vanadium et ses composes

Energy Technology Data Exchange (ETDEWEB)

Morette, Andre

1937-06-03

In this research thesis, the author proposes a new study of the action of some reduction agents on two groups of vanadium compounds, oxides and chlorides. Thus, he reports the study of the circumstances of reduction of vanadium oxides by carbon and of vanadium carburization from these compounds. He also reports the determination of the composition of vanadium melts obtained at high temperatures (either in a vacuum furnace or with an electric arc furnace). In order to determine in which conditions the processing of vanadium oxides could produce the pure metal, the author studied the action of calcium and magnesium on the vanadium pentoxide and trioxide. The second part of the thesis addresses the preparation of pure vanadium from vanadium anhydride chlorides. Then, the author reports the development of processes which could easily produce powdered vanadium [French] Nous nous sommes propose de reprendre l'etude de l'action de quelques reducteurs sur les deux groupes de composes du vanadium, oxydes et chlorures. Nous avons ete ainsi amene a preciser les circonstances de la reduction des oxydes de vanadium par le carbone et de la carburation du vanadium a partir de ceux-ci, puis a determiner la constitution des fontes de vanadium obtenues a haute temperature, soit au four a vide, soit au four a arc. D'autre part, en vue de determiner dans quelles conditions le traitement des oxydes de vanadium pourrait conduire au metal pur, nous avons repris et complete des travaux anterieurs concernant l'action du calcium et du magnesium sur le pentoxyde ou eventuellement le trioxyde de vanadium. Une seconde partie de notre these a ete consacree a la preparation du vanadium pur a partir des chlorures anhydres de vanadium. Nous nous sommes attache a trouver le mode operatoire le plus favorable pour l'obtention de chacun d'eux. Il nous a ete donne ainsi l'occasion de preciser certaines de leurs proprietes physiques et chimiques. Puis, a la suite d'essais systematiques, nous avons

Continuous flow hydrogenation using polysilane-supported palladium/alumina hybrid catalysts

Directory of Open Access Journals (Sweden)

Shū Kobayashi

2011-05-01

Full Text Available Continuous flow systems for hydrogenation using polysilane-supported palladium/alumina (Pd/(PSi–Al2O3 hybrid catalysts were developed. Our original Pd/(PSi–Al2O3 catalysts were used successfully in these systems and the hydrogenation of unsaturated C–C bonds and a nitro group, deprotection of a carbobenzyloxy (Cbz group, and a dehalogenation reaction proceeded smoothly. The catalyst retained high activity for at least 8 h under neat conditions.

Graphitised Carbon Nanofibres as Catalyst Support for PEMFC

DEFF Research Database (Denmark)

Yli-Rantala, E.; Pasanen, A.; Kauranen, P.

2011-01-01

(PANI) precursor. The modified surfaces were studied by FTIR and XPS and the electrochemical characterization, including long-term Pt stability tests, was performed using a low-temperature PEMFC single cell. The performance and stability of the G-CNF supported catalysts were compared with a CB supported...

Determination of trace vanadium using its catalytic effect on the oxidation of gallic acid by bromate

International Nuclear Information System (INIS)

Yamane, Takeshi; Fukasawa, Tsutomu

1976-01-01

The oxidation of gallic acid by bromate with trace vanadium as catalyst was followed spectrophotometrically by measurements of absorbance change at 420 nm. The reaction rate was obtained graphically from the absorbance vs. time curve in the range of about 15 to 40 min. reaction time. The reaction rate was proportional to the concentration of vanadium(V) in the range 0--120 ng (under the conditions of 5.3x10 -3 M gallic acid, 6.0x10 -3 M potassium bromate, pH 3.8) and 0--30 ng (1.1x10 -2 M gallic acid, 2.7x10 -2 M potassium bromate, pH 3.8). Using this relationship, the concentration of vanadium as low as 0.1 ng/ml can be determined. The relative standard deviations at 50 ng and 20 ng of vanadium were 3.5% (n=14) and 4.0% (n=10), respectively. Iron(III) interfered seriously even when present in 20 times the amounts of vanadium. Up to 60 times, W(VI), Mo(VI) and iodide did not interfere. Many of the other ions examined were found to have no effect or slight effect even when present in 1000 times the amounts of vanadium. Other factors affecting the reaction rate were also studied. (auth.)

Phosphorus poisoning of molybdenum sulfide hydrodesulfurization catalysts supported on carbon and alumina

NARCIS (Netherlands)

Bouwens, S.M.A.M.; Vissers, J.P.R.; Beer, de V.H.J.; Prins, R.

1988-01-01

Phosphorus-containing Mo sulfide catalysts supported on ¿-Al2O3 and activated carbon were evaluated for their thiophene HDS activities. Phosphorus was added as phosphoric acid to the carrier material prior to the molybdenum component. The thiophene HDS activity of the carbon-supported catalysts was

Novel synthesis of manganese and vanadium mixed oxide (V2O5/OMS-2) as an efficient and selective catalyst for the oxidation of alcohols in liquid phase

International Nuclear Information System (INIS)

Mahdavi, Vahid; Soleimani, Shima

2014-01-01

Graphical abstract: Oxidation of various alcohols is studied in the liquid phase over new composite mixed oxide (V 2 O 5 /OMS-2) catalyst using tert-butyl hydroperoxide (TBHP). The activity of V 2 O 5 /OMS-2 samples was considerably increased with respect to OMS-2 catalyst and these samples are found to be suitable for the selective oxidation of alcohols. - Highlights: • V 2 O 5 /K-OMS-2 with different V/Mn molar ratios prepared by the impregnation method. • Oxidation of alcohols was studied in the liquid phase over V 2 O 5 /K-OMS-2 catalyst. • V 2 O 5 /K-OMS-2 catalyst had excellent activity for alcohol oxidation. • Benzyl alcohol oxidation using excess TBHP followed a pseudo-first order kinetic. • The selected catalyst was reused without significant loss of activity. - Abstract: This work reports the synthesis and characterization of mixed oxide vanadium–manganese V 2 O 5 /K-OMS-2 at various V/Mn molar ratios and prepared by the impregnation method. Characterization of these new composite materials was made by elemental analysis, BET, XRD, FT-IR, SEM and TEM techniques. Results of these analyses showed that vanadium impregnated samples contained mixed phases of cryptomelane and crystalline V 2 O 5 species. Oxidation of various alcohols was studied in the liquid phase over the V 2 O 5 /K-OMS-2 catalyst using tert-butyl hydroperoxide (TBHP) and H 2 O 2 as the oxidant. Activity of the V 2 O 5 /K-OMS-2 samples was increased considerably with respect to K-OMS-2 catalyst due to the interaction of manganese oxide and V 2 O 5 . The kinetic of benzyl alcohol oxidation using excess TBHP over V 2 O 5 /K-OMS-2 catalyst was investigated at different temperatures and a pseudo-first order reaction was determined with respect to benzyl alcohol. The effects of reaction time, oxidant/alcohol molar ratio, reaction temperature, solvents, catalyst recycling potential and leaching were investigated

thesis of high-purity carbon nanotubes over alumina and silica supported bimetallic catalysts

Directory of Open Access Journals (Sweden)

Sanja Ratković

2009-10-01

Full Text Available Carbon nanotubes (CNTs were synthesized by a catalytic chemical vapor deposition method (CCVD of ethylene over alumina and silica supported bimetallic catalysts based on Fe, Co and Ni. The catalysts were prepared by a precipitation method, calcined at 600 °C and in situ reduced in hydrogen flow at 700 °C. The CNTs growth was carried out by a flow the mixture of C2H4 and nitrogen over the catalyst powder in a horizontal oven. The structure and morphology of as-synthesized CNTs were characterized using SEM. The as-synthesized nanotubes were purified by acid and basic treatments in order to remove impurities such as amorphous carbon, graphite nanoparticles and metal catalysts. XRD and DTA/TG analyses showed that the amounts of by-products in the purified CNTs samples were reduced significantly. According to the observed results, ethylene is an active carbon source for growing high-density CNTs with high yield but more on alumina-supported catalysts than on their silica- supported counterparts. The last might be explained by SMSI formed in the case of alumina-supported catalysts, resulting in higher active phase dispersion.

APS- and XPS-investigations of vanadium, vanadium carbide and graphite

Energy Technology Data Exchange (ETDEWEB)

Bradshaw, A M; Krause, U [Technische Univ. Muenchen (F.R. Germany). Inst. fuer Physikalische Chemie und Theoretische Chemie

1975-11-01

Soft X-ray appearance potential spectroscopy (APS) and X-ray photoelectron spectroscopy (XPS) have been used to study vanadium, vanadium carbide, and graphite. The chemical shifts for vanadium carbide with respect to metallic vanadium and graphite are compared for the two methods. The Csub(K) structure in APS and the valence band in XPS for vanadium carbide show good agreement with the band structure calculations of Neckel and co-workers. Using the band structure calculations of Painter et al. it is also shown how the multi-peak structure in the APS spectrum of graphite is possibly due to density of states effects. It would therefore appear that plasmon coupling plays only a minor role.

Recent Scientific Progress on Developing Supported Ni Catalysts for Dry (CO2 Reforming of Methane

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Hyun Ook Seo

2018-03-01

Full Text Available Two major green house gases (CO2 and CH4 can be converted into useful synthetic gas (H2 and CO during dry reforming of methane (DRM reaction, and a lot of scientific efforts has been made to develop efficient catalysts for dry reforming of methane (DRM. Noble metal-based catalysts can effectively assist DRM reaction, however they are not economically viable. Alternatively, non-noble based catalysts have been studied so far, and supported Ni catalysts have been considered as a promising candidate for DRM catalyst. Main drawback of Ni catalysts is its catalytic instability under operating conditions of DRM (>700 °C. Recently, it has been demonstrated that the appropriate choice of metal-oxide supports can address this issue since the chemical and physical of metal-oxide supports can prevent coke formation and stabilize the small Ni nanoparticles under harsh conditions of DRM operation. This mini-review covers the recent scientific findings on the development of supported Ni catalysts for DRM reaction, including the synthetic methods of supported Ni nanoparticles with high sintering resistance.

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

Energy Technology Data Exchange (ETDEWEB)

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

2017-04-15

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

Heterogeneous Pd catalysts supported on silica matrices

Czech Academy of Sciences Publication Activity Database

Opanasenko, Maksym; Štěpnička, P.; Čejka, Jiří

2014-01-01

Roč. 4, č. 110 (2014), s. 65137-65162 ISSN 2046-2069 R&D Projects: GA ČR GBP106/12/G015 Institutional support: RVO:61388955 Keywords : catalysts * molecular sieves * palladium Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.840, year: 2014

Highly active carbon supported Pd cathode catalysts for direct formic acid fuel cells

Energy Technology Data Exchange (ETDEWEB)

Mikolajczuk-Zychora, A., E-mail: amikolajczuk@ichf.edu.pl [Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw (Poland); Borodzinski, A.; Kedzierzawski, P.; Mierzwa, B. [Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw (Poland); Mazurkiewicz-Pawlicka, M. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Wołoska 141, 02-507 Warsaw (Poland); Faculty of Chemical and Process Engineering, Warsaw University of Technology, Warynskiego 1, Warsaw (Poland); Stobinski, L. [Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw (Poland); Faculty of Chemical and Process Engineering, Warsaw University of Technology, Warynskiego 1, Warsaw (Poland); Ciecierska, E. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Wołoska 141, 02-507 Warsaw (Poland); Zimoch, A.; Opałło, M. [Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw (Poland)

2016-12-01

Highlights: • Palladium catalyst used on the cathode DFAFC is comparable to commercial platinum catalyst. • The treatment of carbon supports in nitric acid(V) increases the electrochemically available metal surface area and the catalytic activity in oxygen reduction reaction of catalysts. - Abstract: One of the drawbacks of low-temperature fuel cells is high price of platinum-based catalysts used for the electroreduction of oxygen at the cathode of the fuel cell. The aim of this work is to develop the palladium catalyst that will replace commonly used platinum cathode catalysts. A series of palladium catalysts for oxygen reduction reaction (ORR) were prepared and tested on the cathode of Direct Formic Acid Fuel Cell (DFAFC). Palladium nanoparticles were deposited on the carbon black (Vulcan) and on multiwall carbon nanotubes (MWCNTs) surface by reduction of palladium(II) acetate dissolved in ethanol. Hydrazine was used as a reducing agent. The effect of functionalization of the carbon supports on the catalysts physicochemical properties and the ORR catalytic activity on the cathode of DFAFC was studied. The supports were functionalized by treatment in nitric acid for 4 h at 80 °C. The structure of the prepared catalysts has been characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscope (TEM) and cyclic voltammetry (CV). Hydrophilicity of the catalytic layers was determined by measuring contact angles of water droplets. The performance of the prepared catalysts has been compared with that of the commercial 20 wt.% Pt/C (Premetek) catalyst. The maximum power density obtained for the best palladium catalyst, deposited on the surface of functionalized carbon black, is the same as that for the commercial Pt/C (Premetek). Palladium is cheaper than platinum, therefore the developed cathode catalyst is promising for future applications.

A phenyl-sulfonic acid anchored carbon-supported platinum catalyst for polymer electrolyte fuel cell electrodes

International Nuclear Information System (INIS)

Selvarani, G.; Sahu, A.K.; Choudhury, N.A.; Sridhar, P.; Pitchumani, S.; Shukla, A.K.

2007-01-01

A method, to anchor phenyl-sulfonic acid functional groups with the platinum catalyst supported onto a high surface-area carbon substrate, is reported. The use of the catalyst in the electrodes of a polymer electrolyte fuel cell (PEFC) helps enhancing its performance. Characterization of the catalyst by Fourier transform infra red (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and point-of-zero-charge (PZC) studies suggests that the improvement in performance of the PEFC is facilitated not only by enlarging the three-phase boundary in the catalyst layer but also by providing ionic-conduction paths as well as by imparting negative charge to platinum sites with concomitant oxidation of sulfur present in the carbon support. It is argued that the negatively charged platinum sites help repel water facilitating oxygen to access the catalyst sites. The PEFC with modified carbon-supported platinum catalyst electrodes exhibits 40% enhancement in its power density as compared to the one with unmodified carbon-supported platinum catalyst electrodes

Evaluation of alumina-aluminium phosphate catalyst supports for hydrodenitrogenation of pyridine and coal-derived liquids

Energy Technology Data Exchange (ETDEWEB)

Menon, R.; Joo, H.S.; Guin, J.A.; Reucroft, P.J.; Kim, J.Y. [Auburn University, Auburn, AL (United States). Dept. of Chemical Engineering

1996-05-01

Several alumina-aluminum phosphate (AAP) catalyst supports were prepared by a coprecipitation method. Effect of variations in Al/P atomic ratios on support textural properties were examined. Finished NiMo/AAP catalysts containing nominally 3 wt% Ni and 13 wt% Mo were prepared by incipient wetness and characterized by several methods including elemental, BET, and XPS surface analysis. Initial hydrodenitrogenation (HDN) activities of the catalysts were examined in both pyridine model compound and coal liquid reactions. The AAP supports showed the opportunity to tailor the catalyst pore size by variation of the Al/P ratio. On a per unit surface areas basis, the AAP-supported catalysts had initial HDN activities comparable to those of a commercial P-promoted NiMo/Al{sub 2}O{sub 3} catalyst. Because of their unique textural properties, i.e. variable pore sizes, the AAP catalysts may offer advantages when dealing with macromolecular feedstocks where hindered diffusion may slow reaction rates. 37 refs., 8 figs., 6 tabs.

Selective oxidation of propylene to acrolein by silica-supported bismuth molybdate catalysts

DEFF Research Database (Denmark)

Duc, Duc Truong; Ha, Hanh Nguyen; Fehrmann, Rasmus

2011-01-01

Silica-supported bismuth molybdate catalysts have been prepared by impregnation, structurally characterized and examined as improved catalysts for the selective oxidation of propylene to acrolein. Catalysts with a wide range of loadings (from 10 to 90 wt%) of beta bismuth molybdate (β-Bi2Mo2O9) w...

The generation of efficient supported (Heterogeneous) olefin metathesis catalysts

Energy Technology Data Exchange (ETDEWEB)

Grubbs, Robert H

2013-04-05

Over the past decade, a new family of homogeneous metathesis catalysts has been developed that will tolerate most organic functionalities as well as water and air. These homogeneous catalysts are finding numerous applications in the pharmaceutical industry as well as in the production of functional polymers. In addition the catalysts are being used to convert seed oils into products that can substitute for those that are now made from petroleum products. Seed oils are unsaturated, contain double bonds, and are a ready source of linear hydrocarbon fragments that are specifically functionalized. To increase the number of applications in the area of biomaterial conversion to petrol chemicals, the activity and efficiency of the catalysts need to be as high as possible. The higher the efficiency of the catalysts, the lower the cost of the conversion and a larger number of practical applications become available. Active supported catalysts were prepared and tested in the conversion of seed oils and other important starting materials. The outcome of the work was successful and the technology has been transferred to a commercial operation to develop viable applications of the discovered systems. A biorefinery that converts seed oils is under construction in Indonesia. The catalysts developed in this study will be considered for the next generation of operations.

Allotropic Carbon Nanoforms as Advanced Metal-Free Catalysts or as Supports

Directory of Open Access Journals (Sweden)

Hermenegildo Garcia

2014-01-01

Full Text Available This perspective paper summarizes the use of three nanostructured carbon allotropes as metal-free catalysts (“carbocatalysts” or as supports of metal nanoparticles. After an introductory section commenting the interest of developing metal-free catalysts and main features of carbon nanoforms, the main body of this paper is focused on exemplifying the opportunities that carbon nanotubes, graphene, and diamond nanoparticles offer to develop advanced catalysts having active sites based on carbon in the absence of transition metals or as large area supports with special morphology and unique properties. The final section provides my personal view on future developments in this field.

Synthesis of cerium oxide catalysts supported on MCM-41 molecular sieve

International Nuclear Information System (INIS)

Souza, E.L.S.; Barros, T.R.B.; Sousa, B.V. de

2016-01-01

Porous materials have been widely studied as catalysts and catalyst support. The MCM-41 structure is the one that has been most studied because of its application possibilities in chemical processes. This work aimed to obtain and characterize cerium oxide catalysts supported on MCM-41 molecular sieve. The molecular sieve was synthesized by the conventional method with the following molar composition: 1 SiO2: 0.30 CTABr: NH3 11: 144 H2O. Then, 25% w/w cerium was incorporated into the MCM-41 using the wet impregnation process and the material obtained was activated by calcination. From the XRD patterns was confirmed the structure of the molecular sieve, and were identified the cerium oxide phases in its structure. The textural catalysts characteristics were investigated by isotherms of N2 adsorption/desorption (BET method). (author)

Highly selective oxidative dehydrogenation of ethane with supported molten chloride catalysts

Energy Technology Data Exchange (ETDEWEB)

Gaertner, C.A.; Veen, A.C. van; Lercher, J.A. [Technische Univ. Muenchen (Germany). Catalysis Research Center

2011-07-01

Ethene production is one of the most important transformations in chemical industry, given that C{sub 2}H{sub 4} serves as building block for many mass-market products. Besides conventional thermal processes like steam cracking of ethane, ethane can be produced selectively by catalytic processes. One of the classes of catalysts that have been reported in literature as active and highly selective for the oxidative dehydrogenation of ethane is that of supported molten chloride catalysts, containing an alkali chloride overlayer on a solid support. This work deals with fundamental aspects of the catalytic action in latter class of catalysts. Results from kinetic reaction studies are related to observations in detailed characterization and lead to a comprehensive mechanistic understanding. Of fundamental importance towards mechanistic insights is the oxygen storage capacity of the catalysts that has been determined by transient step experiments. (orig.)

Modification by SiO2 of Alumina Support for Light Alkane Dehydrogenation Catalysts

Directory of Open Access Journals (Sweden)

Giyjaz E. Bekmukhamedov

2016-10-01

Full Text Available Due to the continuously rising demand for C3–C5 olefins it is important to improve the performance of catalysts for dehydrogenation of light alkanes. In this work the effect of modification by SiO2 on the properties of the alumina support and the chromia-alumina catalyst was studied. SiO2 was introduced by impregnation of the support with a silica sol. To characterize the supports and the catalysts the following techniques were used: low-temperature nitrogen adsorption; IR-spectroscopy; magic angle spinning 29Si nuclear magnetic resonance; temperature programmed desorption and reduction; UV-Vis-, Raman- and electron paramagnetic resonance (EPR-spectroscopy. It was shown that the modifier in amounts of 2.5–7.5 wt % distributed on the support surface in the form of SiOx-islands diminishes the interaction between the alumina support and the chromate ions (precursor of the active component. As a result, polychromates are the compounds predominantly stabilized on the surface of the modified support; under thermal activation of the catalyst and are reduced to the amorphous Cr2O3. This in turn leads to an increase in the activity of the catalyst in the dehydrogenation of isobutane.

Hydrodechlorination of Tetrachloromethane over Palladium Catalysts Supported on Mixed MgF2-MgO Carriers

Directory of Open Access Journals (Sweden)

Magdalena Bonarowska

2016-11-01

Full Text Available Pd/MgO, Pd/MgF2 and Pd/MgO-MgF2 catalysts were investigated in the reaction of CCl4 hydrodechlorination. All the catalysts deactivated in time on stream, but the degree of deactivation varied from catalyst to catalyst. The MgF2-supported palladium with relatively large metal particles appeared the best catalyst, characterized by good activity and selectivity to C2-C5 hydrocarbons. Investigation of post-reaction catalyst samples allowed to find several details associated with the working state of hydrodechlorination catalysts. The role of support acidity was quite complex. On the one hand, a definite, although not very high Lewis acidity of MgF2 is beneficial for shaping high activity of palladium catalysts. The MgO-MgF2 support characterized by stronger Lewis acidity than MgF2 contributes to very good catalytic activity for a relatively long reaction period (~5 h but subsequent neutralization of stronger acid centers (by coking eliminates them from the catalyst. On the other hand, the role of acidity evolution, which takes place when basic supports (like MgO are chlorided during HdCl reactions, is difficult to assess because different events associated with distribution of chlorided support species, leading to partial or even full blocking of the surface of palladium, which plays the role of active component in HdCl reactions.

Polyvinylpolypyrrolidone Supported Brønsted Acidic Catalyst for Esterification

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Song Wang

2016-01-01

Full Text Available A polyvinylpolypyrrolidone (PVPP supported Brønsted acidic catalyst ([PVPP-BS]HSO4 was prepared by coupling SO3H-functionalized polyvinylpolypyrrolidone with H2SO4 in this work. After the characterization through FT-IR, FESEM, TG, BET, and elemental analysis, it was found that 1,4-butane sultone (BS and sulfuric acid reacted with PVPP and were immobilized on PVPP surface. The prepared [PVPP-BS]HSO4 catalyst shows high catalytic activity for a series of esterification reactions and could be separated from the reacted mixture easily. Moreover, this catalyst could be recycled and reused for six times without significant loss of catalytic performance.

Hydrogen Production by Steam Reforming of Ethanol over Nickel Catalysts Supported on Sol Gel Made Alumina: Influence of Calcination Temperature on Supports.

Science.gov (United States)

Yaakob, Zahira; Bshish, Ahmed; Ebshish, Ali; Tasirin, Siti Masrinda; Alhasan, Fatah H

2013-05-30

Selecting a proper support in the catalyst system plays an important role in hydrogen production via ethanol steam reforming. In this study, sol gel made alumina supports prepared for nickel (Ni) catalysts were calcined at different temperatures. A series of (Ni/Al S.G. ) catalysts were synthesized by an impregnation procedure. The influence of varying the calcination temperature of the sol gel made supports on catalyst activity was tested in ethanol reforming reaction. The characteristics of the sol gel alumina supports and Ni catalysts were affected by the calcination temperature of the supports. The structure of the sol gel made alumina supports was transformed in the order of γ → (γ + θ) → θ-alumina as the calcination temperature of the supports increased from 600 °C to 1000 °C. Both hydrogen yield and ethanol conversion presented a volcano-shaped behavior with maximum values of 4.3 mol/mol ethanol fed and 99.5%, respectively. The optimum values were exhibited over Ni/Al S.G800 (Ni catalyst supported on sol gel made alumina calcined at 800 °C). The high performance of the Ni/Al S.G800 catalyst may be attributed to the strong interaction of Ni species and sol gel made alumina which lead to high nickel dispersion and small particle size.

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

Directory of Open Access Journals (Sweden)

A.B. da Silva

1998-06-01

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

Vanadium - 1977

International Nuclear Information System (INIS)

Broderick, G.N.

1977-01-01

This report, with pertinent references, is a comprehensive description and analysis of the vanadium industry. Included is information on industry structure, size and organization; definitions, grades, and specifications; reserves and resources; geology; production and capacity; uses; technology; byproducts and coproducts; strategic considerations; economic and operating factors and problems; supply-demand relationships; and forecasts of supply and demand. Vanadium is used principally as an alloy in steel. Other important uses are in titanium alloys and in various chemical catalytic processes. The world supply of vanadium is sufficient to last far beyond the year 2000 at the present and projected rates of consumption. Almost all of the resources will economically yield vanadium only in conjunction with a coproduct

Physicochemical properties of vanadium impregnated Al-PILCs: Effect of vanadium source

Energy Technology Data Exchange (ETDEWEB)

Balci, Suna, E-mail: sunabalci@gazi.edu.tr; Tecimer, Aylin

2015-03-01

Graphical abstract: - Highlights: • Vanadium was incorporated into Al-PILC using NaVO{sub 3} or VOSO{sub 4}·3H{sub 2}O precursors by wet impregnation, washing after wet impregnation and impregnation from solution methods. • The layered structure of the supports was retained after the vanadium incorporation. • Incorporation took place both by settling and ion exchange mechanism with the treatment VOSO{sub 4}·3H{sub 2}O precursor while settling was dominant in the use of NaVO{sub 3} precursor. • Treatment with VOSO{sub 4}·3H{sub 2}O which was acidic in solution resulted in more structural deformation. • V{sub 2}O{sub 5} and VO{sub 2} were found as the major oxide forms on the impregnated samples. Loading of vanadyl sulfate hydrate (VOSO{sub 4}·H{sub 2}O) resulted in higher V/Si ratio. Most of the vanadium was bonded in +5 oxide form. • Changes in the FTIR signals after vanadium incorporation caused by Brønsted and Lewis sites, silanol, water and vanadium vibrations were occured. • Dehydroxylation of the structure took place around 300 °C. Samples obtained by impregnation and washing after wet impregnation methods resulted in similar mass losses and the wet impregnated sample showed the highest mass loss among the impregnated samples. - Summary: Clay from the Middle Anatolian previously pillared by Al{sub 13}-Keggin ions and then calcined at 300 °C (Al-PILC) was impregnated with aqueous solutions of vanadium precursors by impregnation from solution (I), wet impregnation (WI) and washing after wet impregnation (WWI) methods. The crystal and textural properties were evaluated by X-ray powder diffraction (XRD), nitrogen sorption and transmission electron microscopy (TEM) images. Vanadium incorporation into the Al-PILC resulted decreases in the basal spacing from 1.75 nm to 1.35 nm with the preserved typical layered structure. The use of sodium metavanadate (NaVO{sub 3}) as the source and the impregnation from solution as the incorporation method

Kinetics of Sulfur, Vanadium and Nickel Removal from Basra Crude Oil Hydro Treating

Directory of Open Access Journals (Sweden)

Muzher M. Ibrahim

2013-05-01

Full Text Available     Basra crude oil was hydro treated in trickle–bed reactor using cobalt - molybdenum alumina as a Catalyst. The reaction range temperatures was598 – 648 k, while LHSV was 0.7 – 2 hr-1. The pressure and H2/Oil for all experiments keep constant at 3Mpa and 300 L/L respectively.    Desulphurization and demutualization kinetics were studied and found that the kinetics of sculpture removal is of first – order, and the kinetic of vanadium and nickel removal is of second – order.    Activation energy were calculated and their value are 24.03, 745.86, 63.90 KJ / mole, respectively for sculpture, vanadium, and nickel.

Oxidative dehydration of glycerol to acrylic acid over vanadium-impregnated zeolite beta

Energy Technology Data Exchange (ETDEWEB)

Pestana, Carolina F.M.; Guerra, Antonio C.O.; Turci, Cassia C. [Universidade Federal do Rio de Janeiro, RJ (Brazil). Inst. de Quimica; Ferreira, Glaucio B. [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Inst. de Quimica; Mota, Claudio J.A., E-mail: cmota@iq.ufrj.br [INCT Energia e Ambiente, Universidade Federal do Rio de Janeiro, RJ (Brazil)

2013-01-15

The oxidative dehydration of glycerol to acrylic acid was studied over vanadium-impregnated zeolite Beta. Catalysts were prepared by wet impregnation of ammonium metavanadate over ammonium-exchanged zeolite Beta, followed by air calcination at 823 K. Impregnation reduced the specific surface area, but did not significantly affected the acidity (Bronsted and Lewis) of the zeolites. The catalytic evaluation was carried out in a fixed bed flow reactor using air as the carrier and injecting glycerol by means of a syringe pump. Acrolein was the main product, with acetaldehyde and hydroxy-acetone (acetol) being also formed. Acrylic acid was formed with approximately 25% selectivity at 548 K over the impregnated zeolites. The result can be explained by XPS (X-ray photoelectron spectroscopy) measurements, which indicated a good dispersion of the vanadium inside the pores. (author)

Oxidative dehydration of glycerol to acrylic acid over vanadium-impregnated zeolite beta

International Nuclear Information System (INIS)

Pestana, Carolina F.M.; Guerra, Antonio C.O.; Turci, Cassia C.

2013-01-01

The oxidative dehydration of glycerol to acrylic acid was studied over vanadium-impregnated zeolite Beta. Catalysts were prepared by wet impregnation of ammonium metavanadate over ammonium-exchanged zeolite Beta, followed by air calcination at 823 K. Impregnation reduced the specific surface area, but did not significantly affected the acidity (Bronsted and Lewis) of the zeolites. The catalytic evaluation was carried out in a fixed bed flow reactor using air as the carrier and injecting glycerol by means of a syringe pump. Acrolein was the main product, with acetaldehyde and hydroxy-acetone (acetol) being also formed. Acrylic acid was formed with approximately 25% selectivity at 548 K over the impregnated zeolites. The result can be explained by XPS (X-ray photoelectron spectroscopy) measurements, which indicated a good dispersion of the vanadium inside the pores. (author)

Mesoporous tungsten oxynitride as electrocatalyst for promoting redox reactions of vanadium redox couple and performance of vanadium redox flow battery

Science.gov (United States)

Lee, Wonmi; Jo, Changshin; Youk, Sol; Shin, Hun Yong; Lee, Jinwoo; Chung, Yongjin; Kwon, Yongchai

2018-01-01

For enhancing the performance of vanadium redox flow battery (VRFB), a sluggish reaction rate issue of V2+/V3+ redox couple evaluated as the rate determining reaction should be addressed. For doing that, mesoporous tungsten oxide (m-WO3) and oxyniride (m-WON) structures are proposed as the novel catalysts, while m-WON is gained by NH3 heat treatment of m-WO3. Their specific surface area, crystal structure, surface morphology and component analysis are measured using BET, XRD, TEM and XPS, while their catalytic activity for V2+/V3+ redox reaction is electrochemically examined. As a result, the m-WON shows higher peak current, smaller peak potential difference, higher electron transfer rate constant and lower charge transfer resistance than other catalysts, like the m-WO3, WO3 nanoparticle and mesoporous carbon, proving that it is superior catalyst. Regarding the charge-discharge curve tests, the VRFB single cell employing the m-WON demonstrates high voltage and energy efficiencies, high specific capacity and low capacity loss rate. The excellent results of m-WON are due to the reasons like (i) reduced energy band gap, (ii) reaction familiar surface functional groups and (ii) greater electronegativity.

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

Directory of Open Access Journals (Sweden)

Jakkrit Suriboot

2016-04-01

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

Support effects on hydrotreating activity of NiMo catalysts

International Nuclear Information System (INIS)

Dominguez-Crespo, M.A.; Arce-Estrada, E.M.; Torres-Huerta, A.M.; Diaz-Garcia, L.; Cortez de la Paz, M.T.

2007-01-01

The effect of the gamma alumina particle size on the catalytic activity of NiMoS x catalysts prepared by precipitation method of aluminum acetate at pH = 10 was studied. The structural characterization of the supports was measured by using XRD, pyridine FTIR-TPD and nitrogen physisorption. NiMo catalysts were characterized during the preparation steps (annealing and sulfidation) using transmission electron microscopy (TEM). Hydrogen TPR studies of the NiMo catalysts were also carried out in order to correlate their hydrogenating properties and their catalytic functionality. Catalytic tests were carried out in a pilot plant at 613, 633 and 653 K temperatures. The results showed that the rate constants of hydrodesulfurization (HDS), hydrodenitrogenation (HDN) and hydrodearomatizing (HDA) at 613-653 K decreased in the following order: A > B > C corresponding to the increase of NiMoS particle size associated to these catalysts

Evidence for H2/D2 isotope effects on Fischer-Tropsch synthesis over supported ruthenium catalysts

International Nuclear Information System (INIS)

Kellner, C.S.; Bell, A.T.

1981-01-01

The effects of using D 2 rather than H 2 during Fischer-Tropsch synthesis were investigated using alumina- and silica-supported Ru catalysts. For the alumina-supported catalysts, the rate of CD 4 formation was 1.4 to 1.6 times faster than the formation of CH 4 . A noticeable isotope effect was also observed for higher molecular weight products. The magnitude of the isotope effects observed using the silica-supported catalyst was much smaller than that found using the alumina-supported catalysts. The formation of olefins relative to paraffins was found to be higher when H 2 rather than D 2 was used, independent of the catalyst support. The observed isotope effects are explained in terms of a mechanism for CO hydrogenation and are shown to arise from a complex combination of the kinetic and equilibrium isotope effects associated with elementary processes occurring on the catalyst surface

Leaching characteristics of vanadium in mine tailings and soils near a vanadium titanomagnetite mining site

Energy Technology Data Exchange (ETDEWEB)

Yang, Jinyan; Tang, Ya; Yang, Kai [College of Architecture and Environment, Sichuan University, Chengdu 610065 (China); Rouff, Ashaki A. [School of Earth and Environmental Sciences, Queens College City University of New York, 65-30 Kissena Boulevard, Flushing, NY 11367 (United States); Elzinga, Evert J. [Department of Earth and Environmental Sciences, Rutgers University, Newark, NJ (United States); Huang, Jen-How, E-mail: jen-how.huang@unibas.ch [Institute of Environmental Geosciences, University of Basel, CH-4056 Basel (Switzerland)

2014-01-15

Highlights: • Vanadium in the soil and mine tailings has low solubility. • The leachability of vanadium in the mine tailings is lower than in the soil. • Low risk of vanadium migrating from the soil and mine tailings into the surrounding environment. • Drought and rewetting increase vanadium release from the soil and mine tailings. • Soil leaching processes control vanadium transport in soils overlain with mine tailings. -- Abstract: A series of column leaching experiments were performed to understand the leaching behaviour and the potential environmental risk of vanadium in a Panzhihua soil and vanadium titanomagnetite mine tailings. Results from sequential extraction experiments indicated that the mobility of vanadium in both the soil and the mine tailings was low, with <1% of the total vanadium readily mobilised. Column experiments revealed that only <0.1% of vanadium in the soil and mine tailing was leachable. The vanadium concentrations in the soil leachates did not vary considerably, but decreased with the leachate volume in the mine tailing leachates. This suggests that there was a smaller pool of leachable vanadium in the mine tailings compared to that in the soil. Drought and rewetting increased the vanadium concentrations in the soil and mine tailing leachates from 20 μg L{sup −1} to 50–90 μg L{sup −1}, indicating the potential for high vanadium release following periods of drought. Experiments with soil columns overlain with 4, 8 and 20% volume mine tailings/volume soil exhibited very similar vanadium leaching behaviour. These results suggest that the transport of vanadium to the subsurface is controlled primarily by the leaching processes occurring in soils.

Carbon nanostructures as catalyst support for polymer electrolyte membrane fuel cells

Energy Technology Data Exchange (ETDEWEB)

Natarajan, S.K.; Hamelin, J. [Quebec Univ., Trois Rivieres, PQ (Canada). Inst. de recherche sur l' hydrogene

2008-07-01

This paper reported on a study that investigated potential alternatives to Vulcan XC-72 as a catalyst supports for polymer electrolyte membrane fuel cells (PEMFCs). These included carbon nanostructures (CNS) prepared by high energy ball milling of graphite and transition metal catalysts, followed by heat treatment. Among the key factors discussed were the graphitic content, high surface area, microporous structure, good electrical conductivity and the ability of the material to attach functional groups. Some graphic results supporting the usage of CNS as catalyst support for PEMFCs were presented. Upon chemical oxidation, surface functional groups such as carbonyl, carboxyl, and hydroxyl were populated on the surface of CNS. Nanosized platinum particles with particle size distribution between 3 nm and 5 nm were reduced on the functionalized sites of CNS in a colloidal medium. The paper also presented cyclic voltammograms, XPS, HRTEM and PSD results. 3 refs.

Lithium-Vanadium bronzes as model catalysts for the selective reduction of nitric oxide

NARCIS (Netherlands)

Bosch, H.; Bongers, Annemie; Enoch, Gert; Snel, Ruud; Ross, Julian R.H.

1989-01-01

The effect of alkali metals on the selective reduction of nitric oxide with ammonia has been studied on bulk iron oxide and bulk vanadium oxide. The influence of additions of LiOH, NaOH and KOH on the activity was screened by pulse experiments carried out in the absence of gaseous oxygen; FTIR

Steam Reforming of Acetic Acid over Co-Supported Catalysts: Coupling Ketonization for Greater Stability

Energy Technology Data Exchange (ETDEWEB)

Davidson, Stephen D. [Energy and Environmental; Spies, Kurt A. [Energy and Environmental; Mei, Donghai [Energy and Environmental; Kovarik, Libor [Energy and Environmental; Kutnyakov, Igor [Energy and Environmental; Li, Xiaohong S. [Energy and Environmental; Lebarbier Dagle, Vanessa [Energy and Environmental; Albrecht, Karl O. [Energy and Environmental; Dagle, Robert A. [Energy and Environmental

2017-09-11

We report on the markedly improved stability of a novel 2-bed catalytic system, as compared to a conventional 1-bed steam reforming catalyst, for the production of H2 from acetic acid. The 2-bed catalytic system comprises of i) a basic oxide ketonization catalyst for the conversion of acetic acid to acetone, and a ii) Co-based steam reforming catalyst, both catalytic beds placed in sequence within the same unit operation. Steam reforming catalysts are particularly prone to catalytic deactivation when steam reforming acetic acid, used here as a model compound for the aqueous fraction of bio-oil. Catalysts comprising MgAl2O4, ZnO, CeO2, and activated carbon (AC) both with and without Co-addition were evaluated for conversion of acetic acid and acetone, its ketonization product, in the presence of steam. It was found that over the bare oxide support only ketonization activity was observed and coke deposition was minimal. With addition of Co to the oxide support steam reforming activity was facilitated and coke deposition was significantly increased. Acetone steam reforming over the same Co-supported catalysts demonstrated more stable performance and with less coke deposition than with acetic acid feedstock. DFT analysis suggests that over Co surface CHxCOO species are more favorably formed from acetic acid versus acetone. These CHxCOO species are strongly bound to the Co catalyst surface and could explain the higher propensity for coke formation from acetic acid. Based on these findings, in order to enhance stability of the steam reforming catalyst a dual-bed (2-bed) catalyst system was implemented. Comparing the 2-bed and 1-bed (Co-supported catalyst only) systems under otherwise identical reaction conditions the 2-bed demonstrated significantly improved stability and coke deposition was decreased by a factor of 4.

Dimethyl carbonate synthesis via transesterification of propylene carbonate with methanol by ceria-zinc catalysts: Role of catalyst support and reaction parameters

Energy Technology Data Exchange (ETDEWEB)

Kumar, Praveen; Srivastava, Vimal Chandra; Mishra, Indra Mani [Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand (India)

2015-09-15

Ceria and zinc oxide catalyst were impregnated onto various oxide supports, namely Al{sub 2}O{sub 3}, TiO{sub 2} and SiO{sub 2}, individually by deposition-coprecipitation method. The synthesized catalysts (CZA, CZS and CZT having supports Al{sub 2}O{sub 3}, TiO{sub 2} and SiO{sub 2}, respectively) were characterized by X-ray diffraction (XRD), NH{sub 3}- and CO{sub 2}-temperature programmed desorption (TPD) and N2 adsorption. These catalysts were used for synthesis of dimethyl carbonate (DMC) from methanol and propylene carbonate in a batch reactor. CZS was found to have larger average grain size as compared to CZA and CZT. Composite oxides (catalysts) were found to contain individual phases of ZnO, CeO{sub 2} and some spinel forms of Zn, Ce along with their supports. CZS having highest basicity and surface area showed better catalytic activity as compared to CZA and CZT. Effect of reaction temperature and methanol/PC molar ratio on DMC yield was studied and a reaction mechanism has been discussed. Maximum DMC yield of 77% was observed with CZS catalyst at 170 .deg. C with methanol/PC molar ratio of 10.

Iron oxide/cassava starch-supported Ziegler-Natta catalysts for in situ ethylene polymerization.

Science.gov (United States)

Chancharoenrith, Sittikorn; Kamonsatikul, Choavarit; Namkajorn, Montree; Kiatisevi, Supavadee; Somsook, Ekasith

2015-03-06

Iron oxide nanoparticles were used as supporters for in situ polymerization to produce polymer nanocomposites with well-dispersed fillers in polymer matrix. Iron oxide could be sustained as colloidal solutions by cassava starch to produce a good dispersion of iron oxide in the matrix. New supports based on iron oxide/cassava starch or cassava starch for Ziegler-Natta catalysts were utilized as heterogeneous supporters for partially hydrolyzed triethylaluminum. Then, TiCl4 was immobilized on the supports as catalysts for polymerization of ethylene. High-density polyethylene (HDPE) composites were obtained by the synthesized catalysts. A good dispersion of iron oxide/cassava starch particles was observed in the synthesized polymer matrix promoting to good mechanical properties of HDPE. Copyright © 2014 Elsevier Ltd. All rights reserved.

Physicochemical investigations of carbon nanofiber supported Cu/ZrO2 catalyst

International Nuclear Information System (INIS)

Din, Israf Ud; Shaharun, Maizatul S.; Subbarao, Duvvuri; Naeem, A.

2014-01-01

Zirconia-promoted copper/carbon nanofiber catalysts (Cu‐ZrO 2 /CNF) were prepared by the sequential deposition precipitation method. The Herringbone type of carbon nanofiber GNF-100 (Graphite nanofiber) was used as a catalyst support. Carbon nanofiber was oxidized to (CNF-O) with 5% and 65 % concentration of nitric acid (HNO 3 ). The CNF activated with 5% HNO 3 produced higher surface area which is 155 m 2 /g. The catalyst was characterized by X-ray Diffraction (XRD), Fourier Transform Infra-Red (FTIR) and N 2 adsorption-desorption. The results showed that increase of HNO 3 concentration reduced the surface area and porosity of the catalyst

Coking of residue hydroprocessing catalysts

Energy Technology Data Exchange (ETDEWEB)

Gray, M.R.; Zhao, Y.X. [Alberta Univ., Edmonton, AB (Canada). Dept. of Chemical Engineering; McKnight, C.A. [Syncrude Canada Ltd., Edmonton, AB (Canada); Komar, D.A.; Carruthers, J.D. [Cytec Industries Inc., Stamford, CT (United States)

1997-11-01

One of the major causes of deactivation of Ni/Mo and Co/Mo sulfide catalysts for hydroprocessing of heavy petroleum and bitumen fractions is coke deposition. The composition and amount of coke deposited on residue hydroprocessing catalysts depends on the composition of the liquid phase of the reactor. In the Athabasca bitumen, the high molecular weight components encourage coke deposition at temperatures of 430 to 440 degrees C and at pressures of 10 to 20 MPa hydrogen pressure. A study was conducted to determine which components in the heavy residual oil fraction were responsible for coking of catalysts. Seven samples of Athabasca vacuum residue were prepared by supercritical fluid extraction with pentane before being placed in the reactor. Carbon content and hydrodesulfurization activity was measured. It was concluded that the deposition of coke depended on the presence of asphaltenes and not on other compositional variables such as content of nitrogen, aromatic carbon or vanadium.

Secondary promoters in alumina-supported nickel-molybdenum hydroprocessing catalysts

Energy Technology Data Exchange (ETDEWEB)

Lewis, J.M.

1992-01-01

Two secondary promoters, phosphorus and fluoride, have been investigated for their influences on the physicochemical properties of alumina-supported nickel-molybdenum hydroprocessing catalysts. Model compound reactions and infrared spectroscopy were used to probe the functionalities of the different catalysts, and the catalysts were tested in the hydroprocessing of a low-nitrogen and a high-nitrogen (quinoline-spiked) gas oil feed to assess the utility of the model compound reaction studies. Fluoride-promoted catalysts with high cumene hydrocracking activity and with comparable thiophene hydrodesulphurization (HDS) activity to Ni-Mo/Al[sub 2]O[sub 3] can be prepared by coimpregnation of the F, Ni and Mo additives. Fluoride promotes the hydrogenation (HYD) and HDS activity of Ni-Mo/Al[sub 2]O[sub 3] in the hydroprocessing (HYD) and HDS activity of Ni-Mo/Al[sub 2]O[sub 3] in the hydroprocessing of a low-nitrogen feed. Fluoride promotes the quinoline hydrodenitrogenation (HDN) activity of Ni-Mo/Al[sub 2]O[sub 3] catalysts. Impregnation of phosphorus prior to the metal additives results in catalysts which are more active in HDS. Phosphorus increases indirectly the Broensted acidity of the catalyst by increasing the activity of the MoS[sub 2]-associated acid sites. Phosphorus promotes the HDSW and HYD activities of Ni-Mo/Al[sub 2]O[sub 3] in the hydroprocessing of the low-N feed. A promotional effect of phosphorus is seen in quinoline HDN. P- and F-promoted Ni-MO/Al[sub 2]O[sub 3] catalysts are very active in quinoline HDN and maintain good activity in HDS and HYD of the high-N feed. Thiophene HDS was a good reaction for probing the activity of catalysts in the HDS of sterically-unhindered molecules, but an inaccurate probe for the HDS of hindered compounds.

Preparation of Mesoporous Silica-Supported Palladium Catalysts for Biofuel Upgrade

Directory of Open Access Journals (Sweden)

Ling Fei

2012-01-01

Full Text Available We report the preparation of two hydrocracking catalysts Pd/CoMoO4/silica and Pd/CNTs/CoMoO4/silica (CNTs, carbon nanotubes. The structure, morphologies, composition, and thermal stability of catalysts were studied by X-ray diffraction (XRD, scanning electron microscopy (SEM, Raman spectroscopy, transmission electron microscopy (TEM, energy-dispersive X-ray (EDX, and thermogravimetric analysis (TGA. The catalyst activity was measured in a Parr reactor with camelina fatty acid methyl esters (FAMEs as the feed. The analysis shows that the palladium nanoparticles have been incorporated onto mesoporous silica in Pd/CoMoO4/silica or on the CNTs surface in Pd/CNTs/CoMoO4/silica catalysts. The different combinations of metals and supports have selective control cracking on heavy hydrocarbons.

The utilization of hydroxyapatite-supported CaO-CeO_2 catalyst for biodiesel production

International Nuclear Information System (INIS)

Yan, Beibei; Zhang, Ying; Chen, Guanyi; Shan, Rui; Ma, Wenchao; Liu, Changye

2016-01-01

Highlights: • Hydroxyapatite derived from waste animal bones was served as the support for bimetallic CaO-CeO_2 catalyst. • The 30%CaO-CeO_2/HAP-650 catalyst exhibited excellent performance on biodiesel production. • The yield of FAME was 84.4 % after eight cycles. • Minor leaching concentrations of cerium and calcium species were detected in the product. - Abstract: The study investigated the effect of a bimetallic supported catalyst in biodiesel production. Calcined waste bone derived hydroxyapatite (HAP), a solid waste from animal, was served as the support for CaO-CeO_2 catalyst. Various characterization techniques such as FT-IR, BET, SEM-EDS, CO_2-TPD and XRD analysis were used to analyse the activity of this heterogeneous catalyst. The effect of main parameters in preparation process such as calcination temperature and active component loading on catalyst performance were discussed to obtain the optimal preparation conditions. Under the optimal reaction conditions (11 wt.% dosage of 30%CaO-CeO_2/HAP-650 catalyst and 9:1 methanol to oil molar ratio at 65 °C for 3 h) the highest biodiesel yield of 91.84% was obtained. Stability test indicated that the yield (84.4%) of fatty acid methyl ester was produced after 8 re-used cycles due to the low leaching of catalyst components. The experimental results showed that biodiesel production cost might be lowered while producing relatively high yield at the present of long life-span catalyst.

Analysis of vanadium slags, roasted and leached products. Determination of contents of total vanadium, chromium, sodium, and soluble vanadium

International Nuclear Information System (INIS)

Hasek, Z.

1975-01-01

Accurate, rapid and simple methods were elaborated of determining total vanadium, chromium, and sodium in vanadium slags, and in roasted and leached products in one sample batch. The analysis was conducted in a teflon vial using inorganic acids. A method od determining soluble vanadium in similar materials was also elaborated and verified. (B.S.)

Hydrogen Temperature-Programmed Desorption (H2 TPD) of Supported Platinum Catalysts.

NARCIS (Netherlands)

Koningsberger, D.C.; Miller, J.T.; Meyers, B.L.; Modica, F.S.; Lane, G.S.; Vaarkamp, M.

1993-01-01

Hydrogen temperature-programmed desorption (TPD) of supported platinum catalysts, Pt/KLTL, Pt/H-LTL, Pt/K-MAZ, Pt/H-MAZ, Pt/-Al2O3, and Pt/SiO2, was performed after hydrogen reduction at 300, 450, or 650°C. For all catalysts, reversible desorption of chemisorbed hydrogen occurred at approximately

Synthesis and comparison of the activities of a catalyst supported on two silicate materials

Energy Technology Data Exchange (ETDEWEB)

Vieira, Eduardo G., E-mail: eduardogv5007@gmail.com [Departamento de Física e Química, Unesp-Univ Estadual Paulista, Av. Brasil, 56-Centro, Caixa Postal 31, CEP 15385-000, Ilha Solteira, São Paulo (Brazil); Silva, Rafael O.; Carmo, Devaney R. do [Departamento de Física e Química, Unesp-Univ Estadual Paulista, Av. Brasil, 56-Centro, Caixa Postal 31, CEP 15385-000, Ilha Solteira, São Paulo (Brazil); Junior, Enes F. [Departamento de Fitotecnia, Tecnologia de Alimentos e Sócio Economia, Faculdade de Engenharia de Ilha Solteira, Universidade Estadual Paulista, Ilha Solteira, São Paulo (Brazil); Dias Filho, Newton L., E-mail: nldias@unesc.net [Departamento de Física e Química, Unesp-Univ Estadual Paulista, Av. Brasil, 56-Centro, Caixa Postal 31, CEP 15385-000, Ilha Solteira, São Paulo (Brazil); Universidade do Extremo Sul Catarinense, Av. Universitaria, 1105, CP 3167, CEP 88806-000, Criciúma, SC (Brazil)

2017-04-15

The focus of this work is inspecting the synthesis and comparison of the activities of a catalyst supported on two silicate materials in the epoxidation of 1-octene. The two new catalyst materials were characterized by infrared spectroscopy, elemental analysis, solid-state {sup 29}Si and {sup 13}C nuclear magnetic resonance, scanning electronic microscope (SEM) and analysis of nitrogen. Lastly, the two new catalysts, Silsesq-TCA-[(W(CO){sub 3}I{sub 2}){sub 3}] and Silica-TCA-[W(CO){sub 3}I{sub 2}] were tested as catalysts in reactions of epoxidation of 1-octene and compared with their analogue not supported [W(CO){sub 3}I{sub 2}(thiocarbamide)]. After an extensive literature search, we verified that our work is the first that has reported the immobilization process of [W(CO){sub 3}I{sub 2}(NCCH{sub 3}){sub 2}] on silsesquioxane and silica gel functionalized with propyl-thiocarbamide groups and their applications as catalysts of reactions of catalytic epoxidation of 1-octene. - Highlights: • Immobilization of [W(CO){sub 3}I{sub 2}(NCCH{sub 3}){sub 2}] complex onto mesoporous supports. • Synthesis and characterization of new mesoporous catalysts. • The new catalysts exhibit great catalytic activity in the epoxidation of 1-octene. • Recyclable catalysts with excellent reusability and stability.

Preparation of supported heterogeneous catalysts by pulse impregnation: Application to Ru[sub 3](CO)[sub 12]/2,2[prime]-bipyridine/SiO[sub 2] catalyst

Energy Technology Data Exchange (ETDEWEB)

Haukka, M.; Pakkanen, T.A. (Univ. of Joensuu (Finland))

1994-07-01

In this paper, the authors introduce pulse impregnation, a method for preparing supported heterogeneous catalysts by successive impregnation cycles. Pulse impregnation is a method for preparing supported heterogeneous catalysts from the liquid phase. In the pulse-impregnation technique the catalyst surface is grown gradually in consecutive cycles, with each cycle consisting of separate deposition and activation steps. During the deposition step, the catalyst precursor or precursors are deposited onto the support from a suitable solvent. The actual chemically bonded catalyst phase is formed during the activation step (e.g., thermal activation). Pulse impregnation was tested in the separate deposition of 2,2[prime]-bipyridine and Ru[sub 3](CO)[sub 12] onto a silica support, and in the preparation of Ru[sub 3](CO)[sub 12]/2,2[prime]-bipyridine/SiO[sub 2] catalyst, in a column-type reactor system. Macroscopically uniform deposition was achieved with both 2,2[prime]-bipyridine and Ru[sub 3](CO)[sub 12]. Various solvent systems were used to control the amount of solute adsorbed during deposition. In the preparation of the Ru[sub 3](CO)[sub 12]/2,2[prime]-bipyridine/SiO[sub 2] catalyst, the ruthenium content increased nearly linearly with the number of preparation cycles. The effects of the preparation method on the catalyst activity was also tested in 1-hexane hydroformylation. 31 refs., 7 figs., 1 tab.

Vanadium alloys for the radiative divertor program of DIII-D

International Nuclear Information System (INIS)

Smith, J.P.; Johnson, W.R.; Stambaugh, R.D.; Trester, P.W.; Smith, D.; Bloom, E.

1995-10-01

Vanadium alloys provide an attractive solution for fusion power plants as they exhibit a potential for low environmental impact due to low level of activation from neutron fluence and a relatively short half-life. They also have attractive material properties for use in a reactor. General Atomics along with Argonne National Laboratory (ANL) and Oak Ridge National Laboratory (ORNL), has developed a plan to utilize vanadium alloys as part of the Radiative Divertor Project (RDP) modification for the DIII-D tokamak. The goal for using vanadium alloys is to provide a meaningful step towards developing advanced materials for fusion power applications by demonstrating the in-service behavior of a vanadium alloy (V-4Cr-4Ti) in a tokamak in conjunction with developing essential fabrication technology for the manufacture of full-scale vanadium alloy components. A phased approach towards utilizing vanadium in DIII-D is being used starting with small coupons and samples, advancing to a small component, and finally a portion of the new double-null, slotted divertor will be fabricated from vanadium alloy product forms. A major portion of the program is research and development to support fabrication and resolve key issues related to environmental effects

Nature of the metal-support interface in supported metal catalysts: results from x-ray absorption spectroscopy

NARCIS (Netherlands)

Koningsberger, D.C.; Gates, B.C.

1992-01-01

X-ray absorption spectra characterizing the metal-support interface in supported metal complexes and supported metal catalysts are summarized and evaluated with 29 refs. Mononuclear transition metal complexes on non-reducible metal oxide supports are bonded with metal-oxygen bonds of .apprx.2.15

Copper nanoparticle-deposited graphite felt electrodes for all vanadium redox flow batteries

International Nuclear Information System (INIS)

Wei, L.; Zhao, T.S.; Zeng, L.; Zhou, X.L.; Zeng, Y.K.

2016-01-01

Highlights: • Copper nanoparticle is proposed as electrocatalyst for VRFBs for the first time. • Propose a binder-free copper nanoparticle decorated electrode. • The energy efficiency is up to 80.1% at 300 mA cm"−"2, enhancing more than 17%. • High stability and capacity retention are achieved by battery with copper catalyst. - Abstract: A copper nanoparticle deposited graphite felt electrode for all vanadium redox flow batteries (VRFBs) is developed and tested. It is found that the copper catalyst enables a significant improvement in the electrochemical kinetics of the V"3"+/V"2"+ redox reaction. The battery’s utilization of the electrolyte and energy efficiency are found to be as high as 83.7% and 80.1%, at a current density of 300 mA cm"−"2, which are 53.1% and 17.8% higher than those of the battery without the catalyst. Moreover, the present battery shows a good stability during the cycle test. The results suggest that the inexpensive copper nanoparticle catalyst without tedious preparation process offers a great promise for VRFB application.

The role of Ni in sulfided carbon-supported Ni-Mo hydrodesulfurization catalysts

NARCIS (Netherlands)

Bouwens, S.M.A.M.; Barthe-Zahir, N.; Beer, de V.H.J.; Prins, R.

1991-01-01

The thiophene hydrodesulfurization activities of Ni and Ni---Mo sulfide catalysts supported on activated carbon were measured at atmospheric pressure and the catalyst structures were studied by means of X-ray photoelectron spectroscopy, dynamic oxygen chemisorption, and chemical sulfur analysis. The

Surface-reconstructed graphite nanofibers as a support for cathode catalysts of fuel cells.

Science.gov (United States)

Gan, Lin; Du, Hongda; Li, Baohua; Kang, Feiyu

2011-04-07

Graphite nanofibers (GNFs), on which surface graphite edges were reconstructed into nano-loops, were explored as a cathode catalyst support for fuel cells. The high degree of graphitization, as well as the surface-reconstructed nano-loops that possess topological defects for uniform metal deposition, resulted in an improved performance of the GNF-supported Pt catalyst.

Ceramic wash-coat for catalyst support

Science.gov (United States)

Kulkarni, Anand A.; Subramanian, Ramesh; Sabol, Stephen M.

2012-08-14

A wash-coat (16) for use as a support for an active catalyst species (18) and a catalytic combustor component (10) incorporating such wash-coat. The wash-coat is a solid solution of alumina or alumina-based material (Al.sub.2O.sub.3-0-3 wt % La.sub.2O.sub.3) and a further oxide exhibiting a coefficient of thermal expansion that is lower than that exhibited by alumina. The further oxide may be silicon dioxide (2-30 wt % SiO.sub.2), zirconia silicate (2-30 wt % ZrSiO.sub.4), neodymium oxide (0-4 wt %), titania (Al.sub.2O.sub.3-3-40% TiO.sub.2) or alumina-based magnesium aluminate spinel (Al.sub.2O.sub.3-25 wt % MgO) in various embodiments. The active catalyst species may be palladium and a second metal in a concentration of 10-50% of the concentration of the palladium.

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

International Nuclear Information System (INIS)

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

1979-01-01

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

Ni catalysts with different promoters supported on zeolite for dry reforming of methane

KAUST Repository

Alotaibi, Raja; Alenazey, Feraih; Alotaibi, Faisal; Wei, Nini; Al-Fatesh, Ahmed; Fakeeha, Anis

2015-01-01

Dry reforming of methane (DRM) is considered a high endothermic reaction with operating temperatures between 700 and 1000 °C to achieve high equilibrium conversion of CH4 and CO2 to the syngas (H2 and CO). The conventional catalysts used for DRM are Ni-based catalysts. However, many of these catalysts suffer from the short longevity due to carbon deposition. This study aims to evaluate the effect of La and Ca as promoters for Ni-based catalysts supported on two different zeolite supports, ZL (A) (BET surface area = 925 m2/g, SiO2/Al2O3 mol ratio = 5.1), and ZL (B) (BET surface area = 730 m2/g, SiO2/Al2O3 mol ratio = 12), for DRM. The physicochemical properties of the prepared catalysts were characterized with XRD, BET, TEM and TGA. These catalysts were tested for DRM in a microtubular reactor at reaction conditions of 700 °C. The catalyst activity results show that the catalysts Ni/ZL (B) and Ca-Ni/ZL (B) give the highest methane conversion (60 %) with less time on stream stability compared with promoted Ni on ZL (A). In contrast, La-containing catalysts, La-Ni/ZL (B), show more time on stream stability with minimum carbon content for the spent catalyst indicating the enhancement of the promoters to the Ni/ZL (A) and (B), but with less catalytic activity performance in terms of methane and carbon dioxide conversions due to rapid catalyst deactivation.

Ni catalysts with different promoters supported on zeolite for dry reforming of methane

KAUST Repository

Alotaibi, Raja

2015-07-08

Dry reforming of methane (DRM) is considered a high endothermic reaction with operating temperatures between 700 and 1000 °C to achieve high equilibrium conversion of CH4 and CO2 to the syngas (H2 and CO). The conventional catalysts used for DRM are Ni-based catalysts. However, many of these catalysts suffer from the short longevity due to carbon deposition. This study aims to evaluate the effect of La and Ca as promoters for Ni-based catalysts supported on two different zeolite supports, ZL (A) (BET surface area = 925 m2/g, SiO2/Al2O3 mol ratio = 5.1), and ZL (B) (BET surface area = 730 m2/g, SiO2/Al2O3 mol ratio = 12), for DRM. The physicochemical properties of the prepared catalysts were characterized with XRD, BET, TEM and TGA. These catalysts were tested for DRM in a microtubular reactor at reaction conditions of 700 °C. The catalyst activity results show that the catalysts Ni/ZL (B) and Ca-Ni/ZL (B) give the highest methane conversion (60 %) with less time on stream stability compared with promoted Ni on ZL (A). In contrast, La-containing catalysts, La-Ni/ZL (B), show more time on stream stability with minimum carbon content for the spent catalyst indicating the enhancement of the promoters to the Ni/ZL (A) and (B), but with less catalytic activity performance in terms of methane and carbon dioxide conversions due to rapid catalyst deactivation.

Silica-supported, single-site titanium catalysts for olefin epoxidation. A molecular precursor strategy for control of catalyst structure.

Science.gov (United States)

Jarupatrakorn, Jonggol; Don Tilley, T

2002-07-17

A molecular precursor approach involving simple grafting procedures was used to produce site-isolated titanium-supported epoxidation catalysts of high activity and selectivity. The tris(tert-butoxy)siloxy titanium complexes Ti[OSi(O(t)Bu)(3)](4) (TiSi4), ((i)PrO)Ti[OSi(O(t)Bu)(3)](3) (TiSi3), and ((t)BuO)(3)TiOSi(O(t)Bu)(3) (TiSi) react with the hydroxyl groups of amorphous Aerosil, mesoporous MCM-41, and SBA-15 via loss of HO(t)Bu and/or HOSi(O(t)Bu)(3) and introduction of titanium species onto the silica surface. Powder X-ray diffraction, nitrogen adsorption/desorption, infrared, and diffuse reflectance ultraviolet spectroscopies were used to investigate the structures and chemical natures of the surface-bound titanium species. The titanium species exist mainly in isolated, tetrahedral coordination environments. Increasing the number of siloxide ligands in the molecular precursor decreases the amount of titanium that can be introduced this way, but also enhances the catalytic activity and selectivity for the epoxidation of cyclohexene with cumene hydroperoxide as oxidant. In addition, the high surface area mesoporous silicas (MCM-41 and SBA-15) are more effective than amorphous silica as supports for these catalysts. Supporting TiSi3 on the SBA-15 affords highly active cyclohexene epoxidation catalysts (0.25-1.77 wt % Ti loading) that provide turnover frequencies (TOFs) of 500-1500 h(-1) after 1 h (TOFs are reduced by about half after calcination). These results demonstrate that oxygen-rich siloxide complexes of titanium are useful as precursors to supported epoxidation catalysts.

Development of supported noble metal catalyst for U(VI) to U(IV) reduction

International Nuclear Information System (INIS)

Tyagi, Deepak; Varma, Salil; Bhattacharyya, K.; Tripathi, A.K.; Bharadwaj, S.R.; Jain, V.K.; Sahu, Avinash; Vincent, Tessy; Jagatap, B.N.; Wattal, P.K.

2015-01-01

Uranium-plutonium separation is an essential step in the PUREX process employed in spent nuclear fuel reprocessing. This partitioning in the PUREX process is achieved by selective reduction of Pu(IV) to Pu(III) using uranous nitrate as reductant and hydrazine as stabilizer. Currently in our Indian reprocessing plants, the requirement of uranous nitrate is met by electrolytic reduction of uranyl nitrate. This process, however, suffers from a major drawback of incomplete reduction with a maximum conversion of ~ 60%. Catalytic reduction of U(VI) to U(IV) is being considered as one of the promising alternatives to the electro-reduction process due to fast kinetics and near total conversion. Various catalysts involving noble metals like platinum (Adams catalyst, Pt/Al 2 O 3 , Pt/SiO 2 etc.) have been reported for the reduction. Sustained activity and stability of the catalyst under harsh reaction conditions are still the issues that need to be resolved. We present here the results on zirconia supported noble metal catalyst that is developed in BARC for reduction of uranyl nitrate to uranous nitrate. Supported noble metal catalysts with varying metal loadings (0.5 - 2 wt%) were prepared via support precipitation and noble metal impregnation. The green catalysts were reduced either by chemical reduction using hydrazine hydrate or by heating in hydrogen flow or combination of both the steps. These catalysts were characterized by various techniques such as, XRD, SEM, TEM, N 2 adsorption and H 2 chemisorption. Performance of these catalysts was evaluated for U(VI) to U(IV) reduction with uranyl nitrate feed using hydrazine as reductant. The results with the most active catalyst are named as 'BARC-CAT', which was developed in our lab. (author)

Hydrogen production by steam reforming of liquefied natural gas over a nickel catalyst supported on mesoporous alumina xerogel

Science.gov (United States)

Seo, Jeong Gil; Youn, Min Hye; Cho, Kyung Min; Park, Sunyoung; Song, In Kyu

Mesoporous alumina xerogel (A-SG) is prepared by a sol-gel method for use as a support for a nickel catalyst. The Ni/A-SG catalyst is then prepared by an impregnation method, and is applied to hydrogen production by steam reforming of liquefied natural gas (LNG). The effect of the mesoporous alumina xerogel support on the catalytic performance of Ni/A-SG catalyst is investigated. For the purpose of comparison, a nickel catalyst supported on commercial alumina (A-C) is also prepared by an impregnation method (Ni/A-C). Both the hydroxyl-rich surface and the electron-deficient sites of the A-SG support enhance the dispersion of the nickel species on the support during the calcination step. The formation of the surface nickel aluminate phase in the Ni/A-SG catalyst remarkably increases the reducibility and stability of the catalyst. Furthermore, the high-surface area and the well-developed mesoporosity of the Ni/A-SG catalyst enhance the gasification of surface hydrocarbons that are adsorbed in the reaction. In the steam reforming of LNG, the Ni/A-SG catalyst exhibits a better catalytic performance than the Ni/A-C catalyst in terms of LNG conversion and hydrogen production. Moreover, the Ni/A-SG catalyst shows strong resistance toward catalyst deactivation.

Carbon nanocages: a new support material for Pt catalyst with remarkably high durability.

Science.gov (United States)

Wang, Xiao Xia; Tan, Zhe Hua; Zeng, Min; Wang, Jian Nong

2014-03-24

Low durability is the major challenge hindering the large-scale implementation of proton exchange membrane fuel cell (PEMFC) technology, and corrosion of carbon support materials of current catalysts is the main cause. Here, we describe the finding of remarkably high durability with the use of a novel support material. This material is based on hollow carbon nanocages developed with a high degree of graphitization and concurrent nitrogen doping for oxidation resistance enhancement, uniform deposition of fine Pt particles, and strong Pt-support interaction. Accelerated degradation testing shows that such designed catalyst possesses a superior electrochemical activity and long-term stability for both hydrogen oxidation and oxygen reduction relative to industry benchmarks of current catalysts. Further testing under conditions of practical fuel cell operation reveals almost no degradation over long-term cycling. Such a catalyst of high activity, particularly, high durability, opens the door for the next-generation PEMFC for "real world" application.

The influence of a silica pillar in lamellar tetratitanate for selective catalytic reduction of NOx using NH3

International Nuclear Information System (INIS)

Nogueira da Cunha, Beatriz; Gonçalves, Alécia Maria; Gomes da Silveira, Rafael; Urquieta-González, Ernesto A.; Magalhães Nunes, Liliane

2015-01-01

Highlights: • Potassium ions significantly affected the SCR. • The introduction of silica in the catalyst promotes the NH 3 -SCR reaction. • The catalysts activities were not significantly influenced by SO 2 addition. - Abstract: Silica-pillared layered titanate (SiO 2 –Ti 4 O 9 ) was prepared by intercalating organosilanes into the interlayers of a layered K 2 Ti 4 O 9 followed by calcination at 500 °C. The lamellar titanates produced were used as a support to prepare vanadium catalysts (1 and 2 wt%) through wet impregnation for selective catalytic reduction (SCR) of NO. The catalysts were characterized using nitrogen adsorption (BET), X-ray diffraction (XRD), temperature programmed reduction (H 2 -TPR), nuclear magnetic resonance ( 29 Si NMR), and infrared spectroscopy (FT-IR). Reduction of NO by NH 3 was studied in a fixed-bed reactor packed with the catalysts and fed a mixture comprising 1% NH 3 , 1% NO, 10% O 2 , and 34 ppm SO 2 (when used) in helium. The results demonstrate that activity is correlated with the support, i.e., with acidic strength of catalysts. The potassium in the support, K 2 Ti 4 O 9 , significantly affected the reaction and level of vanadium species reduction. The catalyst (1VSiT) with 1 wt% vanadium impregnated on the SiO 2 –Ti 4 O 9 support reduced ∼80% of the NO. Approximately the same conversion rate was generated on the catalyst (2VSiT) with 2 wt% vanadium using the same support. The increased NH 3 adsorption demonstrate that introduction of silica in the catalyst promotes the NH 3 -SCR reaction. More importantly, 2VSiT and 1VSiT were strongly resistant to SO 2 poisoning

The influence of a silica pillar in lamellar tetratitanate for selective catalytic reduction of NO{sub x} using NH{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Nogueira da Cunha, Beatriz; Gonçalves, Alécia Maria; Gomes da Silveira, Rafael [Institute of Chemistry, Federal University of Goiás, C. Postal 131, CEP 74001-970 Goiânia, GO (Brazil); Urquieta-González, Ernesto A. [Laboratory of Applied Catalysis, Department of Chemical Engineering, Federal University of Sao Carlos, Rodovia Washington Luis Km 235, C. Postal 676, CEP 13565-905 São Carlos, SP (Brazil); Magalhães Nunes, Liliane, E-mail: lilianemnunes@gmail.com [Institute of Chemistry, Federal University of Goiás, C. Postal 131, CEP 74001-970 Goiânia, GO (Brazil)

2015-01-15

Highlights: • Potassium ions significantly affected the SCR. • The introduction of silica in the catalyst promotes the NH{sub 3}-SCR reaction. • The catalysts activities were not significantly influenced by SO{sub 2} addition. - Abstract: Silica-pillared layered titanate (SiO{sub 2}–Ti{sub 4}O{sub 9}) was prepared by intercalating organosilanes into the interlayers of a layered K{sub 2}Ti{sub 4}O{sub 9} followed by calcination at 500 °C. The lamellar titanates produced were used as a support to prepare vanadium catalysts (1 and 2 wt%) through wet impregnation for selective catalytic reduction (SCR) of NO. The catalysts were characterized using nitrogen adsorption (BET), X-ray diffraction (XRD), temperature programmed reduction (H{sub 2}-TPR), nuclear magnetic resonance ({sup 29}Si NMR), and infrared spectroscopy (FT-IR). Reduction of NO by NH{sub 3} was studied in a fixed-bed reactor packed with the catalysts and fed a mixture comprising 1% NH{sub 3}, 1% NO, 10% O{sub 2}, and 34 ppm SO{sub 2} (when used) in helium. The results demonstrate that activity is correlated with the support, i.e., with acidic strength of catalysts. The potassium in the support, K{sub 2}Ti{sub 4}O{sub 9}, significantly affected the reaction and level of vanadium species reduction. The catalyst (1VSiT) with 1 wt% vanadium impregnated on the SiO{sub 2}–Ti{sub 4}O{sub 9} support reduced ∼80% of the NO. Approximately the same conversion rate was generated on the catalyst (2VSiT) with 2 wt% vanadium using the same support. The increased NH{sub 3} adsorption demonstrate that introduction of silica in the catalyst promotes the NH{sub 3}-SCR reaction. More importantly, 2VSiT and 1VSiT were strongly resistant to SO{sub 2} poisoning.

Carbon Nanofibers as Catalyst Support for Noble Metals

NARCIS (Netherlands)

Toebes, M.L.

2004-01-01

In the quest for new and well-defined support materials for heterogeneous catalysts we explored the potential of carbon nanofibers (CNF). CNF belongs to the by now extensive family of synthetic graphite-like carbon materials with advantageous and tunable physico-chemical properties. Aim of the work

MASS TRANSFER IN PORE STRUCTURES OF SUPPORTED CATALYSTS

Directory of Open Access Journals (Sweden)

F.R.C. Silva

1997-09-01

Full Text Available The effects of gas-solid interaction and mass transfer in fixed-bed systems of supported catalysts were analyzed for g -Al2O3 (support and Cu/g -Al2O3 (catalyst systems. Evaluations of the mass transfer coefficients in the macropores and of the diffusivity in the micropores, as formed by the crystallite agglomerates of the metallic phases, were obtained. Dynamic experiments with gaseous tracers permitted the quantification of the parameters based on models for these two pore structures. With a flow in a range of 18 cm3 s-1 to 39.98 cm3 s-1 at 45oC, 65oC and 100oC, mass transfer coefficients km =4.33x10-4 m s-1 to 7.38x10-4 m s-1 for macropore structures and diffusivities Dm =1.29x10-11 m2 s-1 to 5.35x10-11 m2 s-1 for micropore structures were estimated

Carbon Nanofiber Supported Transition-Metal Carbide Catalysts for the Hydrodeoxygenation of Guaiacol

NARCIS (Netherlands)

Jongerius, A.; Gosselink, R.W.; Dijkstra, J.; Bitter, J.H.; Bruijnincx, P.C.A.; Weckhuysen, B.M.

2013-01-01

Hydrodeoxygenation (HDO) studies over carbon nanofiber-supported (CNF) W2C and Mo2C catalysts were performed on guaiacol, a prototypical substrate to evaluate the potential of a catalyst for valorization of depolymerized lignin streams. Typical reactions were executed at 55 bar hydrogen pressure

Highly active carbon supported Pd cathode catalysts for direct formic acid fuel cells

Science.gov (United States)

Mikolajczuk-Zychora, A.; Borodzinski, A.; Kedzierzawski, P.; Mierzwa, B.; Mazurkiewicz-Pawlicka, M.; Stobinski, L.; Ciecierska, E.; Zimoch, A.; Opałło, M.

2016-12-01

One of the drawbacks of low-temperature fuel cells is high price of platinum-based catalysts used for the electroreduction of oxygen at the cathode of the fuel cell. The aim of this work is to develop the palladium catalyst that will replace commonly used platinum cathode catalysts. A series of palladium catalysts for oxygen reduction reaction (ORR) were prepared and tested on the cathode of Direct Formic Acid Fuel Cell (DFAFC). Palladium nanoparticles were deposited on the carbon black (Vulcan) and on multiwall carbon nanotubes (MWCNTs) surface by reduction of palladium(II) acetate dissolved in ethanol. Hydrazine was used as a reducing agent. The effect of functionalization of the carbon supports on the catalysts physicochemical properties and the ORR catalytic activity on the cathode of DFAFC was studied. The supports were functionalized by treatment in nitric acid for 4 h at 80 °C. The structure of the prepared catalysts has been characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscope (TEM) and cyclic voltammetry (CV). Hydrophilicity of the catalytic layers was determined by measuring contact angles of water droplets. The performance of the prepared catalysts has been compared with that of the commercial 20 wt.% Pt/C (Premetek) catalyst. The maximum power density obtained for the best palladium catalyst, deposited on the surface of functionalized carbon black, is the same as that for the commercial Pt/C (Premetek). Palladium is cheaper than platinum, therefore the developed cathode catalyst is promising for future applications.

Wet catalyst-support films for production of vertically aligned carbon nanotubes.

Science.gov (United States)

Alvarez, Noe T; Hamilton, Christopher E; Pint, Cary L; Orbaek, Alvin; Yao, Jun; Frosinini, Aldo L; Barron, Andrew R; Tour, James M; Hauge, Robert H

2010-07-01

A procedure for vertically aligned carbon nanotube (VA-CNT) production has been developed through liquid-phase deposition of alumoxanes (aluminum oxide hydroxides, boehmite) as a catalyst support. Through a simple spin-coating of alumoxane nanoparticles, uniform centimer-square thin film surfaces were coated and used as supports for subsequent deposition of metal catalyst. Uniform VA-CNTs are observed to grow from this film following deposition of both conventional evaporated Fe catalyst, as well as premade Fe nanoparticles drop-dried from the liquid phase. The quality and uniformity of the VA-CNTs are comparable to growth from conventional evaporated layers of Al(2)O(3). The combined use of alumoxane and Fe nanoparticles to coat surfaces represents an inexpensive and scalable approach to large-scale VA-CNT production that makes chemical vapor deposition significantly more competitive when compared to other CNT production techniques.

On possibility of preparation of catalysts for ammonia synthesis based on cyanocomplexes of some d-metals

International Nuclear Information System (INIS)

Sergeeva, A.N.; Dovgej, V.V.; Pavlenko, L.I.; Zubritskaya, D.I.; Tkachenko, Zh.I.; Okorskaya, A.P.; Lyubchenko, Yu.A.

1983-01-01

The catalytic properties of the systems prepared on the basis of coordination cyanides of iron, ruthenium, osmium, rhenium, molydenum, vanadium and other d-metals in the ammonia synthesis reaction are studied. It has been found that thermal stability of catalytic systems containing vanadium and molybdenum is considerably higher than that of the industrial sample of similar type containing aluminium. The systems prepared on the basis of hexacyanoferrates, ruthenates and osmates can be referred to low-temperature type catalysts

Effect of Support Pretreatment Temperature on the Performance of an Iron Fischer–Tropsch Catalyst Supported on Silica-Stabilized Alumina

Directory of Open Access Journals (Sweden)

Kamyar Keyvanloo

2018-02-01

Full Text Available The effect of support material pretreatment temperature, prior to adding the active phase and promoters, on Fischer–Tropsch activity and selectivity was explored. Four iron catalysts were prepared on silica-stabilized alumina (AlSi supports pretreated at 700 °C, 900 °C, 1100 °C or 1200 °C. Addition of 5% silica to alumina made the AlSi material hydrothermally stable, which enabled the unusually high support pretreatment temperatures (>900 °C to be studied. High-temperature dehydroxylation of the AlSi before impregnation greatly reduces FeO·Al2O3 surface spinel formation by removing most of the support-surface hydroxyl groups leading to more effectively carbided catalyst. The activity increases more than four-fold for the support calcined at elevated temperatures (1100–1200 °C compared with traditional support calcination temperatures of <900 °C. This unique pretreatment also facilitates the formation of ε′-Fe2.2C rather than χ-Fe2.5C on the AlSi support, which shows an excellent correlation with catalyst productivity.

Electrocatalytic properties of graphite nanofibers-supported platinum catalysts for direct methanol fuel cells.

Science.gov (United States)

Park, Soo-Jin; Park, Jeong-Min; Seo, Min-Kang

2009-09-01

Graphite nanofibers (GNFs) treated at various temperatures were used as carbon supports to improve the efficiency of PtRu catalysts. The electrochemical properties of the PtRu/GNFs catalysts were then investigated to evaluate their potential for application in DMFCs. The results indicated that the particle size and dispersibility of PtRu in the catalysts were changed by heat treatment, and the electrochemical activity of the catalysts was improved. Consequently, it was found that heat treatments could have an influence on the surface and structural properties of GNFs, resulting in enhancing an electrocatalytic activity of the catalysts for DMFCs.

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

NARCIS (Netherlands)

Bezemer, G.L.

2006-01-01

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

Carbon-supported cobalt catalyst for hydrogen generation from alkaline sodium borohydride solution

Energy Technology Data Exchange (ETDEWEB)

Xu, Dongyan; Liu, Xinmin; Cao, Changqing; Guo, Qingjie [College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Dai, Ping [College of Electromechanical Engineering, Qingdao University of Science and Technology, Qingdao 266061 (China)

2008-08-01

Low cost transition metal catalysts with high performance are attractive for the development of on-board hydrogen generation systems by catalytic hydrolysis of sodium borohydride (NaBH{sub 4}) in fuel cell fields. In this study, hydrogen production from alkaline NaBH{sub 4} via hydrolysis process over carbon-supported cobalt catalysts was studied. The catalytic activity of the supported cobalt catalyst was found to be highly dependent on the calcination temperatures. The hydrogen generation rate increases with calcination temperatures in the range of 200-400 C, but a high calcination temperature above 500 C led to markedly decreased activity. X-ray diffraction patterns reveal that the catalysts experience phase transition from amorphous Co-B to crystalline cobalt hydroxide with increase in calcination temperatures. The reaction performance is also dependent on the concentration of NaBH{sub 4}, and the hydrogen generation rate increases for lower NaBH{sub 4} concentrations and decreases after reaching a maximum at 10 wt.% of NaBH{sub 4}. (author)

Life Support Catalyst Regeneration Using Ionic Liquids and In Situ Resources

Science.gov (United States)

Abney, Morgan B.; Karr, Laurel; Paley, Mark S.; Donovan, David N.

2016-01-01

Oxygen recovery from metabolic carbon dioxide is an enabling capability for long-duration manned space flight. Complete recovery of oxygen (100%) involves the production of solid carbon. Catalytic approaches for this purpose, such as Bosch technology, have been limited in trade analyses due in part to the mass penalty for high catalyst resupply caused by carbon fouling of the iron or nickel catalyst. In an effort to mitigate this challenge, several technology approaches have been proposed. These approaches have included methods to prolong the life of the catalysts by increasing the total carbon mass loading per mass catalyst, methods for simplified catalyst introduction and removal to limit the resupply container mass, methods of using in situ resources, and methods to regenerate catalyst material. Research and development into these methods is ongoing, but only use of in situ resources and/or complete regeneration of catalyst material has the potential to entirely eliminate the need for resupply. The use of ionic liquids provides an opportunity to combine these methods in a technology approach designed to eliminate the need for resupply of oxygen recovery catalyst. Here we describe the results of an initial feasibility study using ionic liquids and in situ resources for life support catalyst regeneration, we discuss the key challenges with the approach, and we propose future efforts to advance the technology.

Graphite-supported platinum catalysts: Effects of gas and aqueous phase treatments

Energy Technology Data Exchange (ETDEWEB)

Vleeming, J.H.; Kuster, B.F.M.; Marin, G.B. [Eindhoven Univ. of Technology (Netherlands)] [and others

1997-03-01

The effects on the platinum particle diameter and the available platinum surface area of a graphite-supported platinum catalyst resulting from pretreatments and from performing a selective oxidation reaction are investigated. In the gas phase considerable catalyst sintering occurs only in the presence of oxygen at 773 K due to extensive carbon burn-off, whereas in an aqueous phase platinum particle growth is limited upon oxidative treatment. A hydrogen treatment in aqueous phase at 363 K causes platinum particle growth, aggregate formation, and covering of metal sites. These phenomena become more important with increasing pH. Platinum particle growth and aggregate formation are attributed to platinum particle rather than platinum adatom mobility and is caused by the destruction of the oxygen-containing surface groups on the graphite support, which serve as anchorage sites for the platinum particles. Site covering is caused by products originating from the graphite support, which are formed as a result of the reductive treatments. When performing the aqueous phase oxidation of methyl {alpha}-D-glucopyranoside at 323 K and a pH of 9, catalyst modifications are small under oxidative conditions. Exposure of the catalyst for several hours to methyl {alpha}-D-glucopyranoside under the same conditions but in the absence of oxygen causes site covering. 50 refs., 9 figs., 1 tab.

Electrochemical dopamine sensor based on P-doped graphene: Highly active metal-free catalyst and metal catalyst support.

Science.gov (United States)

Chu, Ke; Wang, Fan; Zhao, Xiao-Lin; Wang, Xin-Wei; Tian, Ye

2017-12-01

Heteroatom doping is an effective strategy to enhance the catalytic activity of graphene and its hybrid materials. Despite a growing interest of P-doped graphene (P-G) in energy storage/generation applications, P-G has rarely been investigated for electrochemical sensing. Herein, we reported the employment of P-G as both metal-free catalyst and metal catalyst support for electrochemical detection of dopamine (DA). As a metal-free catalyst, P-G exhibited prominent DA sensing performances due to the important role of P doping in improving the electrocatalytic activity of graphene toward DA oxidation. Furthermore, P-G could be an efficient supporting material for loading Au nanoparticles, and resulting Au/P-G hybrid showed a dramatically enhanced electrocatalytic activity and extraordinary sensing performances with a wide linear range of 0.1-180μM and a low detection limit of 0.002μM. All these results demonstrated that P-G might be a very promising electrode material for electrochemical sensor applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Thermodynamics of oxygen in solid solution in vanadium and niobium--vanadium alloys

International Nuclear Information System (INIS)

Steckel, G.L.

1977-01-01

A thermodynamic study was made of the vanadium-oxygen and niobium-vanadium-oxygen systems utilizing the solid state galvanic cell technique. Investigations were made with a ThO 2 /Y 2 O 3 electrolyte over the temperature ranges 700 to 1200 0 C (973 to 1473 K) for the binary system and 650 to 1150 0 C (923 to 1423 K) for the ternary system. The activity of oxygen in vanadium obeys Henry's law for the temperatures of this investigation for concentrations up to 3.2 at. percent oxygen. For higher concentrations the activity coefficient shows positive deviations from Henry's law. The terminal solubility of oxygen in vanadium was determined. The activity of oxygen in Nb--V alloys obeys Henry's law for the temperatures of this study for oxygen concentrations less than approximately 2 at. percent. For certain Nb/V ratios Henry's law is obeyed for concentrations as high as 6.5 at. percent oxygen. First order entropy and enthalpy interaction coefficients have been determined to describe the effect on the oxygen activity of niobium additions to vanadium-rich alloys with dilute oxygen concentrations. Niobium causes relatively small decreases in the oxygen activity of V-rich alloys and increases the oxygen solubility limit. Vanadium additions to Nb-rich alloys also increases the oxygen solubility and causes substantial decreases in the dilute solution oxygen activities. The change in the thermodynamic properties when molecular oxygen dissolves in vanadium and niobium--vanadium alloys and the equilibrium oxygen pressure over the binary and ternary systems were also determined

Co, Fe and Ni catalysts supported on coke for direct coal liquefaction

International Nuclear Information System (INIS)

Jimenez, Jose A; Villalba, Oscar A; Rodriguez, Luis I; Hernandez, Orlando; Agamez, Yasmin Y; Dias Jose de Jesus

2008-01-01

Transition metal catalysts supported on coke were prepared by impregnation with a solution of complex of metal-thiourea, that is produced from salt precursors of cobalt chloride, Nickel chloride or iron sulfate and ammonium. sulphide formation on the support surface was generated by decomposition of the metal complex. The catalysts obtained were used in direct coal liquefaction of a medium volatile bituminous coal (Yerbabuena N 1) from Cundinamarca using a 250 Ml, Parr reactor at 723 K and a hydrogen-donor solvent. The catalytic results show, for all samples, both a good coal conversion and an enhancement of the yield of oils, this indicates that the proposed preparation method of catalyst is effective and that eventually the H 2 S sulphidation conventional process could be replaced

HDS, HDN and HDA activities of nickel-molybdenum catalysts supported on alumina

Energy Technology Data Exchange (ETDEWEB)

Dominguez-Crespo, M.A. [Instituto Mexicano del Petroleo, Programa de Tratamiento de Crudo Maya. Avenida Eje Central Lazaro Cardenas No.152, Col. San Bartolo Atepehuacan, 07730, Mexico D. F. (Mexico); Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada (CICATA-Altamira, IPN) Km 14.5 Carretera Tampico-puerto Industrial 89600, Altamira, Tamaulipas (Mexico); Torres-Huerta, A.M.; Ramirez-Meneses, E. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada (CICATA-Altamira, IPN) Km 14.5 Carretera Tampico-puerto Industrial 89600, Altamira, Tamaulipas (Mexico); Diaz-Garcia, L. [Instituto Mexicano del Petroleo, Programa de Tratamiento de Crudo Maya. Avenida Eje Central Lazaro Cardenas No.152, Col. San Bartolo Atepehuacan, 07730, Mexico D. F. (Mexico); Arce-Estrada, E.M. [Instituto Politecnico Nacional, Departamento de Metalurgia y Materiales. A.P. 75-876, 07300 Mexico, D. F. (Mexico)

2008-08-15

In this work, NiMo-Al{sub 2}O{sub 3} catalysts were prepared by using different alumina precursors. The supports were impregnated by means of the spray at incipient wetness technique in both basic and acid media. Both the supports and fresh catalysts were characterized by the adsorption-desorption isotherms, Temperature-Programmed Reduction (TPR), Thermal Pyridine Adsorption-Desorption (TPD) and X-Ray Diffraction analyses (XRD). After sulfidation, the NiMoS metallic particles were characterized by Transmission Electron Microscopy (TEM). The initial analyses were performed in a trickle-bed reactor by using a real feedstock (Mexican heavy gas oil) and performing hydrotreating reactions (HDS, HDN and HDA) at three different temperatures: 613, 633 and 653 K; and 54 kg cm{sup -} {sup 2}. The catalytic activities are discussed in relation to the physicochemical properties of the NiMo catalysts, alumina phase and pH of the impregnating solution. The catalytic results show an increase in the conversion profiles with temperature. The sulfur conversion was increased from 89 to 99.25%, 91-99%, 90.8-97%, 83-95% and 78-96% when the crystal size of the support varied from 3 to 20 nm, respectively. The nitrogen and aromatic conversions were also increased in the range of 23-45 wt.%. It was found that the {gamma} phase reached a higher catalytic performance than the {eta} phase. The NiMo catalysts synthesized in a basic medium showed a better catalytic performance than that obtained with those prepared in acid solutions. The significance of the kinetic data to compare the catalysts is discussed. The maximum value of the catalytic activity was reached with the catalysts with the smallest particle sizes. (author)

Process intensification by combination of activated carbon supported catalysts and alternative energy sources

OpenAIRE

Calvino Casilda, Vanesa; Pérez-Mayoral, E.

2014-01-01

[EN] Activated carbons are well known for their catalytic properties and for being used as a catalyst support in heterogeneous catalysis. Activated carbons possess most of the desired properties of a catalyst support; inertness towards unwanted reactions, stability under regeneration and reaction conditions, suitable mechanical properties, tunable surface area, porosity, and the possibility of being manufactured in different size and shape. On the other hand, the in...

Catalytic incineration of CO and VOC emissions over supported metal oxide catalysts

Energy Technology Data Exchange (ETDEWEB)

Larsson, Per-Olof

1999-05-01

Catalytic incineration is one of the methods to reduce the emissions of CO and VOCs. Low operation temperature and low catalyst cost are essential parameters for catalytic incinerators. Pt/Al{sub 2}O{sub 3} catalysts are frequently used today, but the cheaper metal oxide catalysts can be very competitive if comparable overall activity is obtained. This thesis concerns how it is possible to decrease the operation temperature for supported metal oxide catalysts by using different supports, active metal oxides and additives. In the thesis it is demonstrated that different copper oxide based catalysts have the best activity and durability for complete oxidation among several tested metal oxide catalysts. CuO{sub x} supported on TiO{sub 2} and Al{sub 2}O{sub 3} showed increased activity with the CuO{sub x} loading up to the threshold coverage for formation of crystalline CuO particles, which is 12 {mu}mol/m{sup 2} on TiO{sub 2} and 6 {mu}mol/m{sup 2} on Al{sub 2}O{sub 3}. Up to the threshold coverage for CuO formation, well dispersed copper oxide species were formed on TiO{sub 2}, and a dispersed copper aluminate surface phase was formed on Al{sub 2}O{sub 3}. Durability tests showed accelerated sintering of TiO{sub 2} by copper, but stabilisation was possible by modification of the TiO{sub 2} with CeO{sub x} before the deposition of CuO{sub x}. The stabilisation was obtained by formation of a Ce-O-Ti surface phase. Addition of CeO{sub x} also enhanced the activity of the copper oxide species thanks to favourable interaction between the active copper oxide species and the CeO{sub x} on the support, which could be seen as increased reducibility in TPR experiments. The increased activity and reducibility was also observed for CuO{sub x} supported on ceria modified Al{sub 2}O{sub 3}. In this regard it was shown that CuO{sub x} deposited on CeO{sub 2}(001) surfaces was substantially more active for CO oxidation than copper oxide deposited on CeO{sub 2}(111) Surfaces. This

Exceptionally Stable and Efficient Solid Supported Hoveyda-Type Catalyst

Czech Academy of Sciences Publication Activity Database

Skowerski, K.; Pastva, J.; Czarnocki, S. J.; Janošcová, Jana

2015-01-01

Roč. 19, č. 7 (2015), s. 872-877 ISSN 1083-6160 Institutional support: RVO:61388955 Keywords : OLEFIN-METATHESIS CATALYSTS * RING-CLOSING METATHESIS * N-HETEROCYCLIC CARBENES Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.922, year: 2015

An extraction process to recover vanadium from low-grade vanadium-bearing titanomagnetite

Energy Technology Data Exchange (ETDEWEB)

Chen, Desheng; Zhao, Hongxin; Hu, Guoping [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing 100190 (China); Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Qi, Tao, E-mail: tqgreen@ipe.ac.cn [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing 100190 (China); Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Yu, Hongdong; Zhang, Guozhi [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing 100190 (China); Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Wang, Lina, E-mail: linawang@ipe.ac.cn [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing 100190 (China); Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Wang, Weijing [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing 100190 (China); Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China)

2015-08-30

Highlights: • The leaching solution contains high concentration of acid, iron, impurities and lower vanadium. • 99.4% of vanadium and 4.2% of iron were extracted by three-stage extraction process. • 99.6% of vanadium and 5.4% of iron were stripped by three-stage stripping process. • The stripping solution contains 40.16 g/L V{sub 2}O{sub 5}, 0.691 g/L Fe, 0.007 g/L TiO{sub 2} and 0.247 g/L CaO. • The vanadium product of V{sub 2}O{sub 5} with purity of 99.12%, 0.026% Fe and well crystallized. - Abstract: An extraction process to recover vanadium from low-grade vanadium-bearing titanomagnetite was developed. In this study, a mixed solvent system of di(2-ethylhexyl) phosphate (D2EHPA) and tri-n-butyl phosphate (TBP) diluted with kerosene was used for the selective extraction of vanadium from a hydrochloric acid leaching solution that contained low vanadium concentration with high concentrations of iron and impurities of Ca, Mg, and Al. In the extraction process, the initial solution pH and the phase ratio had considerable functions in the extraction of vanadium from the hydrochloric acid leaching solution. Under optimal extraction conditions (i.e., 30–40 °C for 10 min, 1:3 phase ratio (O/A), 20% D2EHPA concentration (v/v), and 0–0.8 initial solution pH), 99.4% vanadium and only 4.2% iron were extracted by the three-stage counter-current extraction process. In the stripping process with H{sub 2}SO{sub 4} as the stripping agent and under optimal stripping conditions (i.e., 20% H{sub 2}SO{sub 4} concentration, 5:1 phase ratio (O/A), 20 min stripping time, and 40 °C stripping temperature), 99.6% vanadium and only 5.4% iron were stripped by the three-stage counter-current stripping process. The stripping solution contained 40.16 g/L V{sub 2}O{sub 5}, 0.691g/L Fe, 0.007 g/L TiO{sub 2}, 0.006 g/L SiO{sub 2} and 0.247 g/L CaO. A V{sub 2}O{sub 5} product with a purity of 99.12% V{sub 2}O{sub 5} and only 0.026% Fe was obtained after the oxidation, precipitation

Performance enhancement in vanadium redox flow battery using platinum-based electrocatalyst synthesized by polyol process

International Nuclear Information System (INIS)

Jeong, Sanghyun; Kim, Sunhoe; Kwon, Yongchai

2013-01-01

Sluggish reaction rate of [VO] 2+ /[VO 2 ] + redox couple is an obstacle to be addressed in vanadium redox flow battery (VRFB). To improve the slow reaction rate, Pt/C catalyst synthesized by polyol method is suggested. Its catalytic activity, reaction reversibility and charge–discharge performance are evaluated by half cell and single cell tests, while its crystal structure, particle size and particle distribution are measured by XRD and TEM. The XRD and TEM measurements show the polyol Pt/C catalyst has larger electrochemically active surface (EAS) area and smaller particle size than commercial Pt/C catalyst. When catalytic activities of all the catalysts are estimated, the Pt-included catalysts demonstrate high peak current ratio, small peak potential difference and high electron transfer rate constant, confirming that their catalytic activity and reaction reversibility are excellent. In charge–discharge performance tests, the catalysts indicate high efficiencies as well as low overpotential and internal resistance. Excellent performances of the Pt-included catalysts are attributed to positively charged Pts that serve as active sites for activating [VO] 2+ /[VO 2 ] + reaction. Indeed, adoption of the Pt-included catalysts, especially, use of the polyol Pt/C consisting of uniform and small particles helps improve performance of VRFB

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

Energy Technology Data Exchange (ETDEWEB)

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

2017-04-01

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

The Stability of Supported Gold Catalysts

NARCIS (Netherlands)

Masoud, Nazila

2018-01-01

Gold has supreme cultural and financial value and, in form of nanoparticles smaller than 10 nm, is a unique catalyst for different industrially relevant reactions. Intriguing properties of the gold catalysts have spurred demand in the chemical industry for Au catalysts, the application of which

Vanadium in South Africa

International Nuclear Information System (INIS)

Rohrman, B.

1985-01-01

This paper deals briefly with the history of vanadium and its uses, price movement, and world resources. It then describes the titanomagnetite ore of the Bushveld Complex, and the production of vanadium from this ore at Highveld Steel and Vanadium Corporation Limited, giving details of the various processes used, including the roast-leach, rotary-kiln, electric-smelting, shaking-ladle, and basic-oxygen-furnace operations. The paper concludes with a very brief account of the treatment of Highveld slags in Europe for the production of vanadium pentoxide and ferrovanadium

Characterization of vanadium flow battery

Energy Technology Data Exchange (ETDEWEB)

Bindner, H.; Ekman, C.; Gehrke, O.; Isleifsson, F.

2010-10-15

This report summarizes the work done at Risoe DTU testing a vanadium flow battery as part of the project 'Characterisation of Vanadium Batteries' (ForskEl project 6555) with the partners PA Energy A/S and OI Electric A/S under the Danish PSO energy research program. A 15kW/120kWh vanadium battery has been installed as part of the distributed energy systems experimental facility, SYSLAB, at Risoe DTU. A test programme has been carried out to get hands-on experience with the technology, to characterize the battery from a power system point of view and to assess it with respect to integration of wind energy in the Danish power system. The battery has been in operation for 18 months. During time of operation the battery has not shown signs of degradation of performance. It has a round-trip efficiency at full load of approximately 60% (depending on temperature and SOC). The sources of the losses are power conversion in cell stacks/electrolyte, power converter, and auxiliary power consumption from pumps and controller. The response time for the battery is limited at 20kW/s by the ramp rate of the power converter. The battery can thus provide power and frequency support for the power system. Vanadium battery is a potential technology for storage based services to the power system provided investment and O and M cost are low enough and long term operation is documented. (Author)

Optimal Location of Vanadium in Muscovite and Its Geometrical and Electronic Properties by DFT Calculation

Directory of Open Access Journals (Sweden)

Qiushi Zheng

2017-02-01

Full Text Available Vanadium-bearing muscovite is the most valuable component of stone coal, which is a unique source of vanadium manufacture in China. Numbers of experimental studies have been carried out to destroy the carrier muscovite’s structure for efficient extraction of vanadium. Hence, the vanadium location is necessary for exploring the essence of vanadium extraction. Although most infer that vanadium may substitute for trivalent aluminium (Al as the isomorphism in muscovite for the similar atomic radius, there is not enough experimental evidence and theoretical supports to accurately locate the vanadium site in muscovite. In this study, the muscovite model and optimal location of vanadium were calculated by density functional theory (DFT. We find that the vanadium prefers to substitute for the hexa-coordinated aluminum of muscovite for less deformation and lower substitution energy. Furthermore, the local geometry and relative electronic properties were calculated in detail. The basal theoretical research of muscovite contained with vanadium are reported for the first time. It will make a further influence on the technology development of vanadium extraction from stone coal.

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

Science.gov (United States)

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

NMR evidence of metal-support interaction in syngas conversion catalyst Co-TiO2

International Nuclear Information System (INIS)

Murty, A.N.; Seamster, M.; Thorpe, A.N.; Obermyer, R.T.; Rao, V.U.S.

1990-01-01

To examine the relation between catalytic and magnetic properties, the zero-field NMR spectra and hysteresis loops of cobalt supported on silica, alumina, magnesia, titania, and ZSM-5 with and without the promoter thoria were investigated. Cobalt was incorporated on the support by simple physical admixture of precipitated cobalt and support, and by aqueous impregnation technique. Our studies indicate that the particle sizes are consistently lower in the presence of thoria. Of all the catalysts examined, the Co/Th/TiO 2 catalyst exhibits a high saturation magnetization value---about 20% higher than pure cobalt. In addition, the NMR spectrum of the aqueous impregnation Co/TiO 2 catalyst is distinctly different from the rest. All the NMR lines are shifted to a higher frequency by about 4 MHz. These two features---enhancement of the magnetic moment of cobalt atoms and increases in the hyperfine field at the Co nucleus---clearly indicate that there occurs strong metal-support interaction between cobalt and titania support. The higher hydrocarbon yields observed by the earlier investigators with Co/TiO 2 catalysts might be related to this phenomenon

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

KAUST Repository

Huang, Kuo-Wei; Hengne, Amol Mahalingappa; Bhatte, Kushal Deepak; Ould-Chikh, Samy; Saih, Youssef; Basset, Jean-Marie

2017-01-01

Carbon dioxide hydrogenation to oxygenates (methanol and dimethyl ether (DME)) was investigated over bifunctional supported copper catalysts promoted with gallium (Ga). Supported Cu-Ga nanocomposite catalysts were characterized by X-ray diffraction

Catalytic hydrodechlorination of triclosan using a new class of anion-exchange-resin supported palladium catalysts.

Science.gov (United States)

Han, Bing; Liu, Wen; Li, Jingwen; Wang, Jin; Zhao, Dongye; Xu, Rui; Lin, Zhang

2017-09-01

We prepared a new class of anion-exchange-resin supported Pd catalysts for efficient hydrodechlorination of triclosan in water. The catalysts were prepared through an initial ion-exchange uptake of PdCl 4 2- and subsequent reduction of Pd(II) to Pd(0) nanoparticles at ambient temperature. Two standard strong-base anion exchange resins (IRA-900 and IRA-958) with different matrices (polystyrene and polyacrylic) were chosen as the supports. SEM and TEM images showed that Pd(0) nanoparticles were evenly attached on the resin surface with a mean size of 3-5 nm. The resin supported Pd catalysts (Pd@IRA-900 and Pd@IRA-958) were able to facilitate rapid and complete hydrodechlorination of triclosan. At a Pd loading of 2.0 wt.%, the observed pseudo first-order rate constant (k obs ) was 1.25 ± 0.06 and 1.6 ± 0.1 L/g/min for Pd@IRA-900 and Pd@IRA-958, respectively. The catalysts were more resistant to Cl - poisoning and natural organic matter fouling than other supported-Pd catalysts. The presence of 10 mM NaCl suppressed the k obs value by 31% and 23% for Pd@IRA-900 and Pd@IRA-958, whereas the presence of humic acid at 30 mg/L as TOC lowered the rates by 28% and 27%, respectively. The better performance of Pd@IRA-958 was attributed to the polymeric matrix properties (i.e., hydrophobicity, pore size, and surface area) as well as Pd particle size. GC/MS analyses indicated that very low concentrations of chlorinated intermediates were detected in the early stage of the hydrodechlorination process, with 2-phenoxyphenol being the main byproduct. The catalysts can be repeatedly used in multiple operations without significant bleeding. The catalysts eliminate the need for calcination in preparing conventional supported catalysts, and the resin supports conveniently facilitate control of Pd loading and material properties. Copyright © 2017 Elsevier Ltd. All rights reserved.

Electrochemical evaluation of Pt-Based binary catalysts on various supports for the direct methanol fuel cell

CSIR Research Space (South Africa)

Khotseng, L

2016-01-01

Full Text Available Ru/MoO(sub2) > PtSn/TiO(sub2) > PtRu/TiO(sub2). It was also observed that catalysts supported on MWCNTs were more active than those supported on metal oxides. Furthermore, catalysts supported on MWCNTs proved to be more stable than all the other supported...

The challenges of treating high strength wastewaters: CWAO using MWNT supported ruthenium catalysts

International Nuclear Information System (INIS)

GarcIa, J.; Gomes, H.T.; Figueiredo, J.L.; Faria, J.L.; Garcia, J.; Serp, P.; Kalck, P.

2005-01-01

High strength wastewaters containing aromatic compounds are normally not efficiently treated by conventional methods, including the common biological treatment. In these cases a more sophisticated approach is necessary to attain the desired levels of purification. Catalytic wet air oxidation (CWAO) using carbon based catalysts is employed worldwide as effective pre-treatment of effluents with these characteristics. Carbon materials are preferred as active catalysts or support for preparing them due to their morphological and structural characteristics. In the last 10 years, due to a tremendous development in materials production and processing, carbon nano-structures are becoming more accessible and common widening their range of applications [1]. In this context, the scope of the present work is to illustrate a potential use of multi-walled carbon nano-tubes (MWNT) supported ruthenium catalysts for catalytic wet air oxidation of aniline polluted wastewaters. The metal was supported by incipient wetness and excess impregnation, starting from liquid solutions of three different Ru precursors. Impregnation was carried out on modified MWNT, namely on MWNT-COOH (HNO 3 modified) and MWNT-COONa (HNO 3 /Na 2 CO 3 modified). For the 1% weight Ru/MWNT catalysts, the order of activities decreased in the sequence Ru(COD)(COT)≥RuCl 3 ≥Ru(C 5 H 5 ) 2 . The conversion of aniline after 45 min of reaction was 100% for the catalyst prepared with Ru(COD)(COT). The influence of the Ru precursor, preparation method and the support surface modification was studied comparing the conversion of aniline obtained for the different prepared Ru/MWNT catalysts (Figure 1). MWNT as support material, provide a significant metal dispersion with very small Ru nanoparticles (Figure 2) being observed. This will induce an efficient surface contact between the aniline molecule and the active sites [2]. The excellent catalytic performances of Ru/MWNT are explained in terms of the high dispersion of

A surface science study of model catalysts : II metal-support interactions in Cu/SiO2 model catalysts

NARCIS (Netherlands)

Oetelaar, van den L.C.A.; Partridge, A.; Toussaint, S.L.G.; Flipse, C.F.J.; Brongersma, H.H.

1998-01-01

The thermal stability of wet-chemically prepared Cu/SiO2 model catalysts containing nanometer-sized Cu particles on silica model supports was studied upon heating in hydrogen and ultrahigh vacuum. The surface and interface phenomena that occur are determined by the metal-support interactions.

Metal leaching from refinery waste hydroprocessing catalyst.

Science.gov (United States)

Marafi, Meena; Rana, Mohan S

2018-05-18

The present study aims to develop an eco-friendly methodology for the recovery of nickel (Ni), molybdenum (Mo), and vanadium (V) from the refinery waste spent hydroprocessing catalyst. The proposed process has two stages: the first stage is to separate alumina, while the second stage involves the separation of metal compounds. The effectiveness of leaching agents, such as NH 4 OH, (NH 4 ) 2 CO 3 , and (NH 4 ) 2 S 2 O 8 , for the extraction of Mo, V, Ni, and Al from the refinery spent catalyst has been reported as a function of reagent concentration (0.5 to 2.0 molar), leaching time (1 to 6 h), and temperature (35 to 60°C). The optimal leaching conditions were achieved to obtain the maximum recovery of Mo, Ni, and V metals. The effect of the mixture of multi-ammonium salts on the metal extraction was also studied, which showed an adverse effect for Ni and V, while marginal improvement was observed for Mo leaching. The ammonium salts can form soluble metal complexes, in which stability or solubility depends on the nature of ammonium salt and the reaction conditions. The extracted metals and support can be reused to synthesize a fresh hydroprocessing catalyst. The process will reduce the refinery waste and recover the expensive metals. Therefore, the process is not only important from an environmental point of view but also vital from an economic perspective.

Nano carbon supported platinum catalyst interaction behavior with perfluorosulfonic acid ionomer and their interface structures

DEFF Research Database (Denmark)

Andersen, Shuang Ma

2016-01-01

behavior of Nafion ionomer on platinized carbon nano fibers (CNFs), carbon nano tubes (CNTs) and amorphous carbon (Vulcan). The interaction is affected by the catalyst surface oxygen groups as well as porosity. Comparisons between the carbon supports and platinized equivalents are carried out. It reveals......The interaction between perfluorosulfonic acid ionomer and supported platinum catalyst is essential. It directly influences platinum accessibility, stability of carbon support and platinum, proton conductivity and electron conductivity in an electrode. In this study, we compare the adsorption...... that the platinization step modifies the surface nature of the carbon supports in terms of specific surface area, crystallinity and especially porosity; therefore, ionomer adsorption over carbon is not always representative for the ionomer adsorption over carbon supported catalyst, though indicative. Moreover...

NANOSTRUCTURED METAL OXIDE CATALYSTS VIA BUILDING BLOCK SYNTHESES

Energy Technology Data Exchange (ETDEWEB)

Craig E. Barnes

2013-03-05

A broadly applicable methodology has been developed to prepare new single site catalysts on silica supports. This methodology requires of three critical components: a rigid building block that will be the main structural and compositional component of the support matrix; a family of linking reagents that will be used to insert active metals into the matrix as well as cross link building blocks into a three dimensional matrix; and a clean coupling reaction that will connect building blocks and linking agents together in a controlled fashion. The final piece of conceptual strategy at the center of this methodology involves dosing the building block with known amounts of linking agents so that the targeted connectivity of a linking center to surrounding building blocks is obtained. Achieving targeted connectivities around catalytically active metals in these building block matrices is a critical element of the strategy by which single site catalysts are obtained. This methodology has been demonstrated with a model system involving only silicon and then with two metal-containing systems (titanium and vanadium). The effect that connectivity has on the reactivity of atomically dispersed titanium sites in silica building block matrices has been investigated in the selective oxidation of phenols to benezoquinones. 2-connected titanium sites are found to be five times as active (i.e. initial turnover frequencies) than 4-connected titanium sites (i.e. framework titanium sites).

Removal of toluene by sequential adsorption-plasma oxidation: Mixed support and catalyst deactivation.

Science.gov (United States)

Qin, Caihong; Huang, Xuemin; Zhao, Junjie; Huang, Jiayu; Kang, Zhongli; Dang, Xiaoqing

2017-07-15

A sequential adsorption-plasma oxidation system was used to remove toluene from simulated dry air using γ-Al 2 O 3 , HZSM-5, a mixture of the two materials or their supported Mn-Ag catalyst as adsorbents under atmospheric pressure and room temperature. After 120min of plasma oxidation, γ-Al 2 O 3 had a better carbon balance (∼75%) than HZSM-5, but the CO 2 yield of γ-Al 2 O 3 was only ∼50%; and there was some desorption of toluene when γ-Al 2 O 3 was used. When a mixture of HZSM-5 and γ-Al 2 O 3 with a mass ratio of 1/2 was used, the carbon balance was up to 90% and 82% of this was CO 2 . The adsorption performance and electric discharge characteristics of the mixed supports were tested in order to rationalize this high CO x yield. After seven cycles of sequential adsorption-plasma oxidation, support and Mn-Ag catalyst deactivation occurred. The support and catalyst were characterized before and after deactivation by SEM, a BET method, XRD, XPS and GC-MS in order to probe the mechanism of their deactivation. 97.6% of the deactivated supports and 76% of the deactivated catalysts could be recovered by O 2 temperature-programmed oxidation. Copyright © 2017 Elsevier B.V. All rights reserved.

Deoxygenation of methyl laurate over Ni based catalysts: Influence of supports

Science.gov (United States)

Xia, Xiaoqiang; Chen, Hui; Bi, Yadong; Hu, Jianli

2017-10-01

The use of a series of nickel based catalysts supported over HZSM-5, Al2O3, C and ZrO2 in the deoxygenation of methyl laurate shows that the deoxygenation activity and deoxygenation pathway of nickel based catalysts can be affected by properties of catalysts. In the absence of H2, β-elimination of methyl laurate is the dominant reaction and a small amount of laurate acid is converted into undecane by direct decarboxylation. At the same time, the highly acidic support HZSM-5 gave higher conversion and C11 alkane selectivity. In the presence of H2, Ni/HZSM-5 catalyst showed a significantly high deoxygenation activity, producing 71% alkanes by methyl laurate conversion at 280 °C and 4MPa H2. While as on mildly acidic (Al2O3) and neutral (C) supports, a restricted hydrodeoxygenation activity was achieved but more oxygenate products were yielded. According to the analysis of intermediate product, the deoxygenation reaction of methyl laurate follows three distinct pathways: in the absence of H2, decarboxylation: C11H23COOCH3→C11H23COOH→C11H24; in the presence of H2, decarbonylation: C11H23COOCH3→C11H23COOH→C11H23CHO→C11H24; and hydrodeoxygenation: C11H23COOCH3 →C11H23COOH→C11H23CHO→C12H25OH→C12H26

Atomic Scale Structure-Chemistry Relationships at Oxide Catalyst Surfaces and Interfaces

Science.gov (United States)

McBriarty, Martin E.

Oxide catalysts are integral to chemical production, fuel refining, and the removal of environmental pollutants. However, the atomic-scale phenomena which lead to the useful reactive properties of catalyst materials are not sufficiently understood. In this work, the tools of surface and interface science and electronic structure theory are applied to investigate the structure and chemical properties of catalytically active particles and ultrathin films supported on oxide single crystals. These studies focus on structure-property relationships in vanadium oxide, tungsten oxide, and mixed V-W oxides on the surfaces of alpha-Al2O3 and alpha-Fe2O 3 (0001)-oriented single crystal substrates, two materials with nearly identical crystal structures but drastically different chemical properties. In situ synchrotron X-ray standing wave (XSW) measurements are sensitive to changes in the atomic-scale geometry of single crystal model catalyst surfaces through chemical reaction cycles, while X-ray photoelectron spectroscopy (XPS) reveals corresponding chemical changes. Experimental results agree with theoretical calculations of surface structures, allowing for detailed electronic structure investigations and predictions of surface chemical phenomena. The surface configurations and oxidation states of V and W are found to depend on the coverage of each, and reversible structural shifts accompany chemical state changes through reduction-oxidation cycles. Substrate-dependent effects suggest how the choice of oxide support material may affect catalytic behavior. Additionally, the structure and chemistry of W deposited on alpha-Fe 2O3 nanopowders is studied using X-ray absorption fine structure (XAFS) measurements in an attempt to bridge single crystal surface studies with real catalysts. These investigations of catalytically active material surfaces can inform the rational design of new catalysts for more efficient and sustainable chemistry.

Methanesulfonic acid solution as supporting electrolyte for zinc-vanadium redox battery

International Nuclear Information System (INIS)

Tang Chao; Zhou Debi

2012-01-01

Highlights: ► Methanesulfonic acid as supporting electrolyte for V(V)/V(IV) was discussed. ► V(V)/V(IV) concentration as high as 3 mol L −1 was obtained. ► A Zn-V battery was assembled. ► The assembled Zn-V battery has good cycle performance and high cell voltage. - Abstract: The present work was performed in order to evaluate methanesulfonic acid (MSA) as electrolyte medium for V(IV)/V(V) redox couple as positive species applied in redox flow battery (RFB). V-MSA solutions containing more than 3.0 mol L −1 vanadium ions were obtained. Conductivity and viscosity of 3.0 mol L −1 V(IV)/V(V) electrolyte were determined to be 0.10 cm s −1 and 12.37 mPa s respectively. Cyclic voltammetry was conducted to investigate the electrochemical behavior of V(IV)/V(V) redox couple. The diffusion coefficients of V(IV) on Pt electrode in 1.0, 2.0 and 3.0 mol L −1 V(IV)/V(V) electrolytes determined were 3.606 × 10 −6 , 1.813 × 10 −6 and 0.5244 × 10 −6 cm 2 s −1 , respectively. A Zn-V battery was assembled with V(IV)/V(V)-MSA positive species and Zn/Zn(II)-MSA negative species. The cell voltage in charged state was 1.9–2.0 V and discharge voltage reached up to 1.7 V. The average coulombic efficiency and energy efficiency of the assembled cell were 95.85% and 63.90% respectively and it showed a good cyclic charge–discharge performance, which indicates that MSA has a promise application prospect in vanadium redox battery.

An iron-57 Moessbauer spectroscopic study of titania-supported iron- and iron-iridium catalysts

International Nuclear Information System (INIS)

Berry, F.J.; Jobson, S.

1992-01-01

57 Fe Moessbauer spectroscopy shows that titania-supported iron is reduced by treatment in hydrogen at significantly lower temperatures than corresponding silica- and alumina-supported catalysts. The metallic iron formed under hydrogen at 600deg C is partially converted to carbide by treatment in carbon monoxide and hydrogen. In contrast to its alumina- and silica-supported counterparts, the remainder of the titania-supported iron is unchanged by this gaseous mixture. The 57 Fe Moessbauer spectra of EXAFS show that iron and iridium in the titania-supported iron-iridium catalysts are reduced in hydrogen at even lower temperatures and, after treatment at 600deg C, are predominantly present as the iron-iridium alloy. The treatment of these reduced catalysts in carbon monoxide and hydrogen is shown by Moessbauer spectroscopy and EXAFS to induce the segregation of iron from the iron-iridium alloy and its conversion to iron oxide. (orig.)

Physicochemical investigations of carbon nanofiber supported Cu/ZrO{sub 2} catalyst

Energy Technology Data Exchange (ETDEWEB)

Din, Israf Ud, E-mail: drisraf@yahoo.com, E-mail: maizats@petronas.com.my; Shaharun, Maizatul S., E-mail: drisraf@yahoo.com, E-mail: maizats@petronas.com.my [Department of Fundamental and Applied Sciences, Universiti Teknologi PETRONAS (Malaysia); Subbarao, Duvvuri, E-mail: duvvuri-subbarao@petronas.com.my [Department of Chemical Engineering, Universiti Teknologi PETRONAS (Malaysia); Naeem, A., E-mail: naeeem64@yahoo.com [National Centre of Excellence in Physical Chemistry, University of Peshawar (Pakistan)

2014-10-24

Zirconia-promoted copper/carbon nanofiber catalysts (Cu‐ZrO{sub 2}/CNF) were prepared by the sequential deposition precipitation method. The Herringbone type of carbon nanofiber GNF-100 (Graphite nanofiber) was used as a catalyst support. Carbon nanofiber was oxidized to (CNF-O) with 5% and 65 % concentration of nitric acid (HNO{sub 3}). The CNF activated with 5% HNO{sub 3} produced higher surface area which is 155 m{sup 2}/g. The catalyst was characterized by X-ray Diffraction (XRD), Fourier Transform Infra-Red (FTIR) and N{sub 2} adsorption-desorption. The results showed that increase of HNO{sub 3} concentration reduced the surface area and porosity of the catalyst.

Enhanced Activity and Selectivity of Carbon Nanofiber Supported Pd Catalysts for Nitrite Reduction

KAUST Repository

Shuai, Danmeng; Choe, Jong Kwon; Shapley, John R.; Werth, Charles J.

2012-01-01

Pd-based catalyst treatment represents an emerging technology that shows promise to remove nitrate and nitrite from drinking water. In this work we use vapor-grown carbon nanofiber (CNF) supports in order to explore the effects of Pd nanoparticle size and interior versus exterior loading on nitrite reduction activity and selectivity (i.e., dinitrogen over ammonia production). Results show that nitrite reduction activity increases by 3.1-fold and selectivity decreases by 8.0-fold, with decreasing Pd nanoparticle size from 1.4 to 9.6 nm. Both activity and selectivity are not significantly influenced by Pd interior versus exterior CNF loading. Consequently, turnover frequencies (TOFs) among all CNF catalysts are similar, suggesting nitrite reduction is not sensitive to Pd location on CNFs nor Pd structure. CNF-based catalysts compare favorably to conventional Pd catalysts (i.e., Pd on activated carbon or alumina) with respect to nitrite reduction activity and selectivity, and they maintain activity over multiple reduction cycles. Hence, our results suggest new insights that an optimum Pd nanoparticle size on CNFs balances faster kinetics with lower ammonia production, that catalysts can be tailored at the nanoscale to improve catalytic performance for nitrite, and that CNFs hold promise as highly effective catalyst supports in drinking water treatment. © 2012 American Chemical Society.

Enhanced Activity and Selectivity of Carbon Nanofiber Supported Pd Catalysts for Nitrite Reduction

KAUST Repository

Shuai, Danmeng

2012-03-06

Pd-based catalyst treatment represents an emerging technology that shows promise to remove nitrate and nitrite from drinking water. In this work we use vapor-grown carbon nanofiber (CNF) supports in order to explore the effects of Pd nanoparticle size and interior versus exterior loading on nitrite reduction activity and selectivity (i.e., dinitrogen over ammonia production). Results show that nitrite reduction activity increases by 3.1-fold and selectivity decreases by 8.0-fold, with decreasing Pd nanoparticle size from 1.4 to 9.6 nm. Both activity and selectivity are not significantly influenced by Pd interior versus exterior CNF loading. Consequently, turnover frequencies (TOFs) among all CNF catalysts are similar, suggesting nitrite reduction is not sensitive to Pd location on CNFs nor Pd structure. CNF-based catalysts compare favorably to conventional Pd catalysts (i.e., Pd on activated carbon or alumina) with respect to nitrite reduction activity and selectivity, and they maintain activity over multiple reduction cycles. Hence, our results suggest new insights that an optimum Pd nanoparticle size on CNFs balances faster kinetics with lower ammonia production, that catalysts can be tailored at the nanoscale to improve catalytic performance for nitrite, and that CNFs hold promise as highly effective catalyst supports in drinking water treatment. © 2012 American Chemical Society.

A Facile Synthesis of Hollow Palladium/Copper Alloy Nanocubes Supported on N-Doped Graphene for Ethanol Electrooxidation Catalyst

Directory of Open Access Journals (Sweden)

Zhengyu Bai

2015-04-01

Full Text Available In this paper, a catalyst of hollow PdCu alloy nanocubes supported on nitrogen-doped graphene support (H-PdCu/ppy-NG is successfully synthesized using a simple one-pot template-free method. Two other catalyst materials such as solid PdCu alloy particles supported on this same nitrogen-doped graphene support (PdCu/ppy-NG and hollow PdCu alloy nanocubes supported on the reduced graphene oxide support (H-PdCu/RGO are also prepared using the similar synthesis conditions for comparison. It is found that, among these three catalyst materials, H-PdCu/ppy-NG gives the highest electrochemical active area and both the most uniformity and dispersibility of H-PdCu particles. Electrochemical tests show that the H-PdCu/ppy-NG catalyst can give the best electrocatalytic activity and stability towards the ethanol electrooxidation when compared to other two catalysts. Therefore, H-PdCu/ppy-NG should be a promising catalyst candidate for anodic ethanol oxidation in direct ethanol fuel cells.

Metal Chlorides Supported Solid Catalysts for F-C Acylations of Arenes

Institute of Scientific and Technical Information of China (English)

李阳; 刘云龙; 穆曼曼; 陈立功

2015-01-01

A series of metal chlorides supported solid catalysts were prepared by simple wet impregnation method. Their catalytic performances for Friedel-Crafts acylation of toluene with benzoyl chloride were evaluated and the excellent results were obtained over FeCl3/SiO2. These catalysts were characterized by BET, NH3-TPD and FT-IR of pyridine adsorption to clarify the structure-activity relationship. It was found that FeCl3/SiO2 has larger pore size and pore volume than other catalysts, which increased the accessibility of the catalyst. In addition, FeCl3/SiO2 ex-hibited higher molar ratio of Lewis acid sites and Brφnsted acid sites, which might be another reason for the in-crease of toluene conversion. Furthermore, the reaction parameters, including temperature, time and molar ratio, were optimized. Under the optimized conditions, 91.2%, conversion and 82.0%, selectivity were obtained. Mean-while, the generality of the catalyst was demonstrated by the acylations of alkyl substituted aromatics. Finally, the catalyst was reused for four runs with slight loss in catalytic activity, which attributed to the drain of the active component.

Based on a new support for synthesis of highly efficient palladium/hydroxyapatite catalyst for ethanol electrooxidation

International Nuclear Information System (INIS)

Cui, Qian; Chao, Shujun; Bai, Zhengyu; Yan, Huiying; Wang, Kui; Yang, Lin

2014-01-01

Based on a new support, hydroxyapatite (HAP), a facile and low–cost preparation of palladium/hydroxyapatite catalyst for ethanol electrooxidation is introduced in this paper through a solvothermal reaction without additives. HAP was employed as the catalyst support for its hydroxyl–rich surface in order to increase the stability and utilization ratio of catalyst. According to transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM) and X–ray diffraction (XRD) measurements, the as–prepared Pd nanoparticles with face–centered cubic crystal structure were evenly deposited on the surface of HAP. Cyclic voltammetry and chronoamperometry tests demonstrated that the Pd/HAP catalyst possessed a much higher current density (246 mA cm −2 ) than the Pd/C catalyst (109 mA cm −2 ) towards ethanol electrooxidation, and better stability as well. In the direct ethanol fuel cell (DEFC) test, Pd/HAP catalyst gives better performance than that with Pd/C in terms of both open-circuit voltage (OCV) and power density. These results indicate that the HAP is a better support and the catalyst developed in this study may be a better candidate for DEFCs. A possible mechanism consistent with the experimental is also proposed

XPS analysis of supported catalysts prepared in water-in-oil microemulsion system

International Nuclear Information System (INIS)

Mohd Ambar Yarmo; Wong Hoi Jin; Tan Chew Khim; Anita Ramli; Shahidan Radiman

2002-01-01

Catalysts supported on γ-alumina prepared by water-in-oil microemulsion were studied by X-ray photoelectron spectroscopy for comparison with catalysts prepared by wet impregnation. Comparable shifts to higher binding energies indicated a metal-support interaction where metal obtained via microemulsion is very small in size and highly dispersed. The positive binding energy shifts could be explained from a net unit positive charge remaining on the cluster in the photoemission final state in addition to the metallic screening from a redistribution of states within the bands. (Author)

Catalytic combustion of particulate matter Catalysts of alkaline nitrates supported on hydrous zirconium

International Nuclear Information System (INIS)

Galdeano, N.F.; Carrascull, A.L.; Ponzi, M.I.; Lick, I.D.; Ponzi, E.N.

2004-01-01

In order to explore a method to remove particulate matter, catalysts of different alkaline nitrates (Li, K and Cs) supported on hydrous zirconium were prepared by the method of incipient humidity and tested as catalysts for particulate matter combustion. The catalytic activity was determined by using the temperature programmed oxidation technique (TPO), utilizing two equipments, a thermogravimetric reactor and other of fixed bed. In the first case the particulate matter/catalyst mixture was milled carefully in a mortar (tight contact) while in the second case more realistic operative conditions were used, particulate matter/catalyst mixture was made with a spatula (loose contact). All prepared catalysts showed good activity for the particulate matter combustion. The cesium catalyst was the one that presented higher activity, decreasing the combustion temperature between 200 and 250 deg. C with respect to the combustion without catalyst. The catalyst with lithium nitrate became active at higher temperature than its melting point and the same occurred with the potassium catalyst. This did not occur for the catalyst containing cesium nitrate that melts at 407 deg. C and became active from 350 deg. C

Chemiluminescent determination of vanadium(IV) using a cinchomeronic hydrazide-H2O2 system and flow injection analysis

International Nuclear Information System (INIS)

Pradana Perez, J.A.; Alegria, J.S. Durand; Hernando, P. Fernandez; Sierra, A. Narros

2005-01-01

This paper proposes a new chemiluminescent flow injection analysis (FIA) method for the determination of vanadium(IV) ions in aqueous media. The method is based on the chemiluminescent reaction that occurs between cinchomeronic hydrazide (CH) and hydrogen peroxide in a strongly alkaline medium, in which vanadium(IV) acts as a catalyst. The chemical and physical variables involved in the flow injection system are optimised using a modified simplex method. Vanadium ions can be detected in the 0.08 and 1.00 μg mL -1 range; the detection limit for a signal-to-noise ratio of 3 is 0.08 μg mL -1 . Great variations in the quantum yield were observed when cobalt(II), chromium(III), copper(II) and/or nickel(II) were present in the reaction medium. The proposed method is selective and simple, and can be successfully used to analyse water samples without the need for separation or preconcentration processes

Electrooxidation of ethanol on novel multi-walled carbon nanotube supported platinum-antimony tin oxide nanoparticle catalysts

Energy Technology Data Exchange (ETDEWEB)

Guo, Dao-Jun [School of Chemistry and Chemical Engineering, The Key Laboratory of Life-Organic Analysis, Qufu Normal University, Qufu, Shandong 273165 (China)

2011-01-15

We synthesize the new Pt based catalyst for direct ethanol fuel cells using novel multi-walled carbon nanotubes supported platinum-antimony tin oxide (Pt-ATO/MWCNT) nanoparticle as new catalyst support for the first time. The structure of Pt-ATO/MWCNT catalyst is characterized by transmission electron micrograph (TEM) and X-ray diffraction (XRD). The electrocatalytic properties of Pt-ATO/MWCNT catalyst for ethanol electrooxidation reactions are investigated by cyclic voltammetry (CV) and chronoamperometric experiments in acidic medium. The electrocatalytic activity for ethanol electrooxidation reaction shows that high carbon monoxide tolerance and good stability of Pt-ATO/MWCNT catalyst compared with Pt-SnO{sub 2}/MWCNT and commercial Pt/C are observed. These results imply that Pt-ATO/MWCNT catalyst has promising potential applications in direct alcohol fuel cells. (author)

Characterization and evaluation of Pt-Ru catalyst supported on multi-walled carbon nanotubes by electrochemical impedance

Energy Technology Data Exchange (ETDEWEB)

Ocampo, A.L.; Miranda-Hernandez, M.; Sebastian, P.J. [Centro de Investigacion en Energia-UNAM, Temixco, 62580 Morelos (Mexico); Morgado, J.; Montoya, J.A. [IMP, Eje Central Lazaro Cardenas 152, 07730 D.F. Mexico (Mexico)

2006-10-06

In this work the authors present the results of a systematic characterization and evaluation of the carbon nanotube supported Pt-Ru (Pt-Ru/CNT) for its use as methanol oxidation catalyst. Its activity was compared with that of Pt and Pt-Ru catalysts supported on Vulcan and synthesized from carbonyl precursors, and another commercial Pt-Ru catalyst. The cyclic voltammetry, CO stripping and electrochemical impedance techniques were employed to determine the electrocatalytic activity of the catalysts. The electrochemical studies were performed in 0.5M H{sub 2}SO{sub 4} containing different concentrations of methanol (0.05-1M). The results showed a noticeable influence of the catalyst support (CNT) on the performance of the catalyst for CO oxidation. The electrochemical impedance studies allowed us to separate the different steps in the methanol oxidation reaction and to control these steps or reactions by varying the applied potential and the methanol concentration. At low methanol concentration and potentials the de-hydrogenation of methanol predominated. But, at high potential and methanol concentrations, the CO oxidation predominated. These results allowed us to clearly describe at what potential and concentration ranges the bi-functional effect of Ru becomes evident. Our results indicated that the CO oxidation occurs both on Pt and Ru. Compared to other catalysts, Pt-Ru supported on carbon nanotubes showed superior catalytic activity for CO and methanol oxidation. (author)

Promising SiC support for Pd catalyst in selective hydrogenation of acetylene to ethylene

Science.gov (United States)

Guo, Zhanglong; Liu, Yuefeng; Liu, Yan; Chu, Wei

2018-06-01

In this study, SiC supported Pd nanoparticles were found to be an efficient catalyst in acetylene selective hydrogenation reaction. The ethylene selectivity can be about 20% higher than that on Pd/TiO2 catalyst at the same acetylene conversion at 90%. Moreover, Pd/SiC catalyst showed a stable catalytic life at 65 °C with 80% ethylene selectivity. With the detailed characterization using temperature-programmed reduction (H2-TPR), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 adsorption/desorption analysis, CO-chemisorption and thermo-gravimetric analysis (TGA), it was found that SiC owns a lower surface area (22.9 m2/g) and a broad distribution of meso-/macro-porosity (from 5 to 65 nm), which enhanced the mass transfer during the chemical process at high reaction rate and decreased the residence time of ethylene on catalyst surface. Importantly, SiC support has the high thermal conductivity, which favored the rapid temperature homogenization through the catalyst bed and inhabited the over-hydrogenation of acetylene. The surface electronic density of Pd on Pd/SiC catalyst was higher than that on Pd/TiO2, which could promote desorption of ethylene from surface of the catalyst. TGA results confirmed a much less coke deposition on Pd/SiC catalyst.

Three-dimensional Nitrogen-Doped Reduced Graphene Oxide/Carbon Nanotube Composite Catalysts for Vanadium Flow Batteries

Energy Technology Data Exchange (ETDEWEB)

Fu, Shaofang [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Zhu, Chengzhou [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Song, Junhua [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Engelhard, Mark H. [Environmental Molecular Science Laboratory, Pacific Northwest National Laboratory, Richland, WA 99354 USA.; Du, Dan [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Lin, Yuehe [School of Mechanical and Materials Engineering, Washington State University, WA, 99164 USA.; Environmental Molecular Science Laboratory, Pacific Northwest National Laboratory, Richland, WA 99354 USA.

2017-02-22

The development of vanadium redox flow battery is limited by the sluggish kinetics of the reaction, especially the cathodic VO2+/VO2+ redox couples. Therefore, it is vital to develop new electrocatalyst with enhanced activity to improve the battery performance. Herein, we first synthesized the hydrogel precursor by a facile hydrothermal method. After the following carbonization, nitrogen-doped reduced graphene oxide/carbon nanotube composite was obtained. By virtue of the large surface area and good conductivey, which are ensured by the unique hybrid structure, as well as the proper nitrogen doping, the as-prepared composite presents enhanced catalytic performance toward the VO2+/VO2+ redox reaction. We also demonstrated the composite with carbon nanotube loading of 2 mg/mL exhibits the highest activity and remarkable stability in aqueous solution due to the strong synergy between reduced graphene oxide and carbon nanotubes, indicating that this composite might show promising applications in vanadium redox flow battery.

Characterization and Catalytic Activity of Montmorillonite K10-Supported Cobalt Catalysts

International Nuclear Information System (INIS)

Gobara, H.M.; Ghattas, M.S.; Henien, S.A.

2010-01-01

Montmorillonite K10-supported cobalt catalysts were prepared by wet impregnation method. The samples were analyzed by XRD, TPR, FTTR and BET characterization techniques. [Three phases of cobalt species were identified namely, cobalt oxide (Co 3 O 4 ), cobalt silicate (Co 2 S 1 O 4 ) and cobalt aluminate (CoAl 2 O 4 ). These species were most probably existing within the inter lamellar spaces of the meso porous montmorillonite K10 support]. The two bands observed at 1385 and 760 cm 1 were characteristic of metal species rather than the support, being mostly of Co - O bond vibration. The hysteresis loop, pore size distribution, pore volume and BET surface area were greatly affected by cobalt loading. The catalyst containing 18 wt% cobalt was the most selective sample for ethylene production from ethanol dehydration.

Evaluation of photocatalytic activities of supported catalysts on NaX zeolite or activated charcoal

Energy Technology Data Exchange (ETDEWEB)

Brites-Nóbrega, Fernanda F. de [Chemical Engineering Department, Universidade Estadual de Maringá (UEM), Av. Colombo, 5790, CEP 87020-900 Maringá, PR (Brazil); Sanitary and Environmental Engineering Department, Universidade Federal de Minas Gerais (UFMG), Av. Antônio Carlos, 6627, Campus Pampulha, Belo Horizonte, MG (Brazil); Polo, Aldino N.B.; Benedetti, Angélica M. [Chemical Engineering Department, Universidade Estadual do Oeste do Paraná (UNIOESTE), Rua da Faculdade, 645, CEP 85903-000 Toledo, PR (Brazil); Leão, Mônica M.D. [Sanitary and Environmental Engineering Department, Universidade Federal de Minas Gerais (UFMG), Av. Antônio Carlos, 6627, Campus Pampulha, Belo Horizonte, MG (Brazil); Slusarski-Santana, Veronice, E-mail: veronice.santana@unioeste.br [Chemical Engineering Department, Universidade Estadual do Oeste do Paraná (UNIOESTE), Rua da Faculdade, 645, CEP 85903-000 Toledo, PR (Brazil); Fernandes-Machado, Nádia R.C. [Chemical Engineering Department, Universidade Estadual de Maringá (UEM), Av. Colombo, 5790, CEP 87020-900 Maringá, PR (Brazil)

2013-12-15

Highlights: • The synergic effect between ZnO and NaX was positive, which increased its activity. • The best results were obtained at pH 3 and 9 with ZnO/NaX and at pH 3 with Nb{sub 2}O{sub 5}/AC. • High degradation and considerable mineralization were attained with 10% ZnO/NaX. • ZnO and Nb{sub 2}O{sub 5} supported on NaX and AC are promising alternatives as photocatalysts. -- Abstract: This study aimed to evaluate the photocatalytic activity of ZnO and Nb{sub 2}O{sub 5} catalysts, both supported on NaX zeolite and activated charcoal (AC). The synergistic effect between oxide and support and the influence of solution pH (3, 7 and 9) on photocatalytic degradation of reactive blue 5G (C.I. 222) were analyzed. The catalysts Nb{sub 2}O{sub 5}/NaX, Nb{sub 2}O{sub 5}/AC and ZnO/NaX, ZnO/AC with 5 and 10% (wt%) were prepared by wet impregnation. The results showed that the catalysts exhibit quite different structural and textural properties. The synergic effect between ZnO and NaX support was higher than that with the activated charcoal, showing that these catalysts were more efficient. The most photoactive catalyst was 10% ZnO/NaX which showed 100% discoloration of the dye solution at pH 3, 7 and 9 after 0.5, 5 and 2 h of irradiation, respectively. The hydrolytic nature of zeolite favored the formation of surface hydroxyl radicals, which increased the activity of the photocatalyst. Thus, catalysts supported on NaX zeolite are promising for use in photocatalysis.

Controlled metal nitrate decomposition for the preparation of supported metal Catalysts

NARCIS (Netherlands)

Wolters, M.

2010-01-01

High surface area supported metal (oxide) catalysts are essential for the production of fuels, chemicals, pharmaceuticals and the abatement of environmental pollution. Impregnation of high surface area supports, often silica or alumina, followed by drying, calcination and reduction is one of the

Understanding the Performance and Stability of Supported Ni-Co-Based Catalysts in Phenol HDO

Directory of Open Access Journals (Sweden)

Thuan M. Huynh

2016-11-01

Full Text Available Performances of bimetallic catalysts (Ni-Co supported on different acidic carriers (HZSM-5, HBeta, HY, ZrO2 and corresponding monometallic Ni catalysts in aqueous phase hydrodeoxygenation of phenol were compared in batch and continuous flow modes. The results revealed that the support acidity plays an important role in deoxygenation as it mainly controls the oxygen-removing steps in the reaction network. At the same time, sufficient hydrothermal stability of a solid catalyst is essential. Batch experiments revealed 10Ni10Co/HZSM-5 to be the best-performing catalyst in terms of conversion and cyclohexane yield. Complementary continuous runs provided more insights into the relationship between catalyst structure, efficiency and stability. After 24 h on-stream, the catalyst still reveals 100% conversion and a slight loss (from 100% to 90% in liquid hydrocarbon selectivity. The observed alloy of Co with Ni increased dispersion and stability of Ni-active sites, and combination with HZSM-5 resulted in a well-balanced ratio of metal and acid sites which promoted all necessary steps in preferred pathways. This was proved by studies of fresh and spent catalysts using various characterization techniques (N2 physisorption, X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, transmission electron microscopy (TEM and infrared spectroscopy of adsorbed pyridine (pyr-IR.

Polymer supported organic catalysts for O2 reduction in Li-O2 batteries

International Nuclear Information System (INIS)

Weng, Wei; Barile, Christopher J.; Du, Peng; Abouimrane, Ali; Assary, Rajeev S.; Gewirth, Andrew A.; Curtiss, Larry A.; Amine, Khalil

2014-01-01

Graphical abstract: - Abstract: A novel organic catalyst has been synthesized that contains an anthraquinone moiety supported on a polymer backbone. This oxygen reduction catalyst was successfully incorporated in the cathode of Li-O 2 batteries. The addition of the anthraquinone-based catalyst improved the cycleability of the Li-O 2 battery when cycled in a tetraethylene glycol dimethyl ether electrolyte. Computational studies coupled with a wide range of analytical techniques including differential electrochemical mass spectrometry, cyclic voltammetry, electrochemical impedence spectroscopy, and X-ray diffraction were used to interrogate the Li-O 2 battery with and without the organic catalyst present. This study suggests that organic catalysts may serve as light and inexpensive alternatives to the precious metals frequently used in Li-O 2 batteries

Neurobehavioral and cytotoxic effects of vanadium during oligodendrocyte maturation: a protective role for erythropoietin.

Science.gov (United States)

Mustapha, Oluwaseun; Oke, Bankole; Offen, Nils; Sirén, Anna-Leena; Olopade, James

2014-07-01

Vanadium exposure has been known to lead to lipid peroxidation, demyelination and oligodendrocytes depletion. We investigated behaviour and glial reactions in juvenile mice after early neonatal exposure to vanadium, and examined the direct effects of vanadium in oligodendrocyte progenitor cultures from embryonic mice. Neonatal pups exposed to vanadium via lactation for 15 and 22 days all had lower body weights. Behavioural tests showed in most instances a reduction in locomotor activity and negative geotaxis. Brain analyses revealed astrocytic activation and demyelination in the vanadium exposed groups compared to the controls. In cell culture, exposure of oligodendrocytes to 300 μM sodium metavanadate significantly increased cell death. Expression of the oligodendrocyte specific proteins, 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) and oligodendrocyte specific protein (OSP/Claudin) were reduced upon vanadium treatment while simultaneous administration of erythropoietin (EPO; 4-12 U/ml) counteracted vanadium-toxicity. The data suggest that oligodendrocyte damage may explain the increased vulnerability of the juvenile brain to vanadium and support a potential for erythropoietin as a protective agent against vanadium-toxicity during perinatal brain development and maturation. Copyright © 2014 Elsevier B.V. All rights reserved.

V{sub 2}O{sub 5}-ZrO{sub 2} catalysts for the oxidative dehydrogenation of propane - influence of the niobium oxide doping

Energy Technology Data Exchange (ETDEWEB)

Albrecht, S.; Hallmeier, K.H.; Wendt, G. [Leipzig Univ. (Germany). Fakultaet fuer Chemie und Mineralogie; Lippold, G. [Leipzig Univ. (Germany). Fakultaet fuer Physik und Geowissenschaften

1998-12-31

The oxidative dehydrogenation (ODH) of light alkanes is an alternative way for the production of olefins. A wide variety of catalytic systems has been investigated. Vanadium oxide based catalysts were described in the literature as effective catalysts for the ODH of propane. The catalytic activity and selectivity depend on the kind of support material, the kind of dopants and the formation of complex metal oxide phases. In recent papers it was claimed that both orthovanadate and/or pyrovanadate species are selective for the ODH of propane. Niobia based materials were investigated as catalysts for acidic and selective oxidation type reactions. In the ODH of propane niobia exhibited a high selectivity to propene but the conversion of propane was low. V{sub 2}O{sub 5}-Nb{sub 2}O{sub 5} catalysts proved to be catalytically active and selective and showed no formation of oxygenates. In the present study the influence of the niobia dopant of the catalytic properties of V{sub 2}O{sub 5}-ZrO{sub 2} catalysts in the ODH of propane was examined. The structural and textural properties of the catalysts were investigated using several methods. (orig.)

Melting technique for vanadium containing steels

Energy Technology Data Exchange (ETDEWEB)

Grishanov, M P; Gutovskij, I B; Vakhrushev, A S

1980-04-28

To descrease cost price of high-quality vanadium steels a method of their melting in open-hearth furnaces with acid lining using slag-metal fraction of vanadium, which is loaded in the content of 2.1-4.7% of melting mass, is suggested. Introduction of slag-metal fraction of vanadium ensures the formation of slag with composition that guarantees the necessary content of vanadium in steel and does not require introduction of expensive vanadium-containing ferroalloys into the melt.

The challenges of treating high strength wastewaters: CWAO using MWNT supported ruthenium catalysts

Energy Technology Data Exchange (ETDEWEB)

GarcIa, J.; Gomes, H.T.; Figueiredo, J.L.; Faria, J.L. [Porto Univ., Lab. de Catalise e Materiais, Dept. de Engenharia Quimica, Faculdade de Engenharia (Portugal); Garcia, J. [Madrid Univ. Complutense, Grupo de Catalisis y Operaciones de Separacion, Dept. de Ingenieria Quimica, Facultad de Ciencias (Spain); Serp, P.; Kalck, P. [Ecole Nationale Superieure des Ingenieurs en Arts Chimiques et Technologiques, Lab. de Catalyse, Chimie Fine et Polymeres, 31 - Toulouse (France)

2005-07-01

High strength wastewaters containing aromatic compounds are normally not efficiently treated by conventional methods, including the common biological treatment. In these cases a more sophisticated approach is necessary to attain the desired levels of purification. Catalytic wet air oxidation (CWAO) using carbon based catalysts is employed worldwide as effective pre-treatment of effluents with these characteristics. Carbon materials are preferred as active catalysts or support for preparing them due to their morphological and structural characteristics. In the last 10 years, due to a tremendous development in materials production and processing, carbon nano-structures are becoming more accessible and common widening their range of applications [1]. In this context, the scope of the present work is to illustrate a potential use of multi-walled carbon nano-tubes (MWNT) supported ruthenium catalysts for catalytic wet air oxidation of aniline polluted wastewaters. The metal was supported by incipient wetness and excess impregnation, starting from liquid solutions of three different Ru precursors. Impregnation was carried out on modified MWNT, namely on MWNT-COOH (HNO{sub 3} modified) and MWNT-COONa (HNO{sub 3}/Na{sub 2}CO{sub 3} modified). For the 1% weight Ru/MWNT catalysts, the order of activities decreased in the sequence Ru(COD)(COT){>=}RuCl{sub 3}{>=}Ru(C{sub 5}H{sub 5}){sub 2}. The conversion of aniline after 45 min of reaction was 100% for the catalyst prepared with Ru(COD)(COT). The influence of the Ru precursor, preparation method and the support surface modification was studied comparing the conversion of aniline obtained for the different prepared Ru/MWNT catalysts (Figure 1). MWNT as support material, provide a significant metal dispersion with very small Ru nanoparticles (Figure 2) being observed. This will induce an efficient surface contact between the aniline molecule and the active sites [2]. The excellent catalytic performances of Ru/MWNT are explained

Monodisperse metal nanoparticle catalysts on silica mesoporous supports: synthesis, characterizations, and catalytic reactions

Energy Technology Data Exchange (ETDEWEB)

Somorjai, G.A.

2009-09-14

The design of high performance catalyst achieving near 100% product selectivity at maximum activity is one of the most important goals in the modern catalytic science research. To this end, the preparation of model catalysts whose catalytic performances can be predicted in a systematic and rational manner is of significant importance, which thereby allows understanding of the molecular ingredients affecting the catalytic performances. We have designed novel 3-dimensional (3D) high surface area model catalysts by the integration of colloidal metal nanoparticles and mesoporous silica supports. Monodisperse colloidal metal NPs with controllable size and shape were synthesized using dendrimers, polymers, or surfactants as the surface stabilizers. The size of Pt, and Rh nanoparticles can be varied from sub 1 nm to 15 nm, while the shape of Pt can be controlled to cube, cuboctahedron, and octahedron. The 3D model catalysts were generated by the incorporation of metal nanoparticles into the pores of mesoporous silica supports via two methods: capillary inclusion (CI) and nanoparticle encapsulation (NE). The former method relies on the sonication-induced inclusion of metal nanoparticles into the pores of mesoporous silica, whereas the latter is performed by the encapsulation of metal nanoparticles during the hydrothermal synthesis of mesoporous silica. The 3D model catalysts were comprehensively characterized by a variety of physical and chemical methods. These catalysts were found to show structure sensitivity in hydrocarbon conversion reactions. The Pt NPs supported on mesoporous SBA-15 silica (Pt/SBA-15) displayed significant particle size sensitivity in ethane hydrogenolysis over the size range of 1-7 nm. The Pt/SBA-15 catalysts also exhibited particle size dependent product selectivity in cyclohexene hydrogenation, crotonaldehyde hydrogenation, and pyrrole hydrogenation. The Rh loaded SBA-15 silica catalyst showed structure sensitivity in CO oxidation reaction. In

An efficient hybrid, nanostructured, epoxidation catalyst: titanium silsesquioxane-polystyrene copolymer supported on SBA-15.

Science.gov (United States)

Zhang, Lei; Abbenhuis, Hendrikus C L; Gerritsen, Gijsbert; Bhriain, Nollaig Ní; Magusin, Pieter C M M; Mezari, Brahim; Han, Wei; van Santen, Rutger A; Yang, Qihua; Li, Can

2007-01-01

A novel interfacial hybrid epoxidation catalyst was designed with a new immobilization method for homogeneous catalysts by coating an inorganic support with an organic polymer film containing active sites. The titanium silsesquioxane (TiPOSS) complex, which contains a single-site titanium active center, was immobilized successfully by in-situ copolymerization on a mesoporous SBA-15-supported polystyrene polymer. The resulting hybrid materials exhibit attractive textural properties (highly ordered mesostructure, large specific surface area (>380 m2 g-1) and pore volume (>or==0.46 cm3 g-1)), and high activity in the epoxidation of alkenes. In the epoxidation of cyclooctene with tert-butyl hydrogen peroxide (TBHP), the hybrid catalysts have rate constants comparable with that of their homogeneous counterpart, and can be recycled at least seven times. They can also catalyze the epoxidation of cyclooctene with aqueous H2O2 as the oxidant. In two-phase reaction media, the catalysts show much higher activity than their homogeneous counterpart due to the hydrophobic environment around the active centers. They behave as interfacial catalysts due to their multifunctionality, that is, the hydrophobicity of polystyrene and the polyhedral oligomeric silsesquioxanes (POSS), and the hydrophilicity of the silica and the mesoporous structure. Combination of the immobilization of homogeneous catalysts on two conventional supports, inorganic solid and organic polymer, is demonstrated to achieve novel heterogeneous catalytic ensembles with the merits of attractive textural properties, tunable surface properties, and optimized environments around the active sites.

Characterization of a surface modified carbon cryogel and a carbon supported Pt catalyst

Directory of Open Access Journals (Sweden)

BILJANA M. BABIĆ

2007-08-01

Full Text Available A carbon cryogel, synthesized by carbonization of a resorcinol/formaldehyde cryogel and oxidized in nitric acid, was used as catalyst support for Pt nano-particles. The Pt/C catalyst was prepared by a modified polyol synthesis method in an ethylene glycol (EG solution. Characterization by nitrogen adsorption showed that the carbon cryogel support and the Pt/C catalyst were mesoporous materials with high specific surface areas (SBET > 400 m2 g-1 and large mesoporous volumes. X-Ray diffraction of the catalyst demonstrated the successful reduction of the Pt precursor to metallic form. TEM Images of the Pt/C catalyst and Pt particle size distribution showed that the mean Pt particle size was about 3.3 nm. Cyclic voltammetry (CV experiments at various scan rates (from 2 to 200 mV s-1 were performed in 0.5 mol dm-3 HClO4 solution. The large capacitance of the oxidized carbon cryogel electrode, which arises from a combination of the double-layer capacitance and pseudocapacitance, associated with the participation of surface redox-type reactions was demonstrated. For the oxidized carbon cryogel, the total specific capacitance determined by 1/C vs. ν0.5 extrapolation method was found to be 386 F g-1. The hydrogen oxidation reaction at the investigated Pt/C catalyst proceeded as an electrochemically reversible, two-electron direct discharge reaction.

Final Report - Advanced Cathode Catalysts and Supports for PEM Fuel Cells

Energy Technology Data Exchange (ETDEWEB)

Debe, Mark

2012-09-28

The principal objectives of the program were development of a durable, low cost, high performance cathode electrode (catalyst and support), that is fully integrated into a fuel cell membrane electrode assembly with gas diffusion media, fabricated by high volume capable processes, and is able to meet or exceed the 2015 DOE targets. Work completed in this contract was an extension of the developments under three preceding cooperative agreements/grants Nos. DE-FC-02-97EE50473, DE-FC-99EE50582 and DE-FC36- 02AL67621 which investigated catalyzed membrane electrode assemblies for PEM fuel cells based on a fundamentally new, nanostructured thin film catalyst and support system, and demonstrated the feasibility for high volume manufacturability.

Preparation of ethylene/1-hexene copolymers from ethylene using a fully silica-supported tandem catalyst system

NARCIS (Netherlands)

Karbach, Fabian F.; Macko, Tibor; Duchateau, Robbert

2016-01-01

A silica-supported tandem catalyst system, capable of producing ethylene/1-hexene copolymers from ethylene being the single monomer, has been investigated. As tandem couple a phenoxyimine titanium catalyst for ethylene trimerization was combined with a metallocene catalyst for α-olefin

Synthesis of carbon-supported copper catalyst and its catalytic performance in methanol dehydrogenation

Energy Technology Data Exchange (ETDEWEB)

Shelepova, Ekaterina V. [Boreskov Institute of Catalysis SB RAS, pr. Ac. Lavrentieva, 5, Novosibirsk, 630090 (Russian Federation); National Research Tomsk Polytechnic University, Lenin av., 30, Tomsk, 634050 (Russian Federation); Vedyagin, Aleksey A., E-mail: vedyagin@catalysis.ru [Boreskov Institute of Catalysis SB RAS, pr. Ac. Lavrentieva, 5, Novosibirsk, 630090 (Russian Federation); National Research Tomsk Polytechnic University, Lenin av., 30, Tomsk, 634050 (Russian Federation); Ilina, Ludmila Yu.; Nizovskii, Alexander I. [Boreskov Institute of Catalysis SB RAS, pr. Ac. Lavrentieva, 5, Novosibirsk, 630090 (Russian Federation); Tsyrulnikov, Pavel G. [Institute of Hydrocarbon Processing SB RAS, Neftezavodskaya st., 54, Omsk, 644040 (Russian Federation)

2017-07-01

Highlights: • Carbon-supported copper catalyst was studied in dehydrogenation of methanol. • Reduction temperature affected size of Cu particles and Cu{sup 0}/Cu{sup 2+} ratio. • Reduction at 400 °C was required to obtain high methyl formate yield. - Abstract: Carbon-supported copper catalyst was prepared by incipient wetness impregnation of Sibunit with an aqueous solution of copper nitrate. Copper loading was 5 wt.%. Temperature of reductive pretreatment was varied within a range of 200–400 °C. The samples were characterized by transmission electron microscopy, X-ray diffraction analysis, X-ray photoelectron and X-ray absorption spectroscopies. Catalytic activity of the samples was studied in a reaction of methanol dehydrogenation. Silica-based catalyst with similar copper loading was used as a reference. It was found that copper is distributed over the surface of support in the form of metallic and partially oxidized particles of about 12–17 nm in size. Diminished interaction of copper with support was supposed to be responsible for high catalytic activity.

Active carbon catalyst for heavy oil upgrading

Energy Technology Data Exchange (ETDEWEB)

Fukuyama, Hidetsugu; Terai, Satoshi [Technology Research Center, Toyo Engineering Corporation, 1818 Azafujimi, Togo, Mobara-shi, Chiba 297-00017 (Japan); Uchida, Masayuki [Business Planning and Exploring Department, Overseas Business Development and Marketing Division, Toyo Engineering Corporation, 2-8-1 Akanehama, Narashino-shi, Chiba 275-0024 (Japan); Cano, Jose L.; Ancheyta, Jorge [Maya Crude Treatment Project, Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas No. 152, Col. San Bartolo Atepehuacan, Mexico D.F. 07730 (Mexico)

2004-11-24

The active carbon (AC) catalyst was studied by hydrocracking of Middle Eastern vacuum residue (VR) for heavy oil upgrading. It was observed that the active carbon has the affinity to heavy hydrocarbon compounds and adsorption selectivity to asphaltenes, and exhibits better ability to restrict the coke formation during the hydrocracking reaction of VR. The mesopore of active carbon was thought to play an important role for effective conversion of heavy hydrocarbon compounds into lighter fractions restricting carbon formation. The performance of the AC catalyst was examined by continuous hydrocracking by CSTR for the removal of such impurities as sulfur and heavy metals (nickel and vanadium), which are mostly concentrated in the asphaltenes. The AC catalyst was confirmed to be very effective for the removal of heavy metals from Middle Eastern VR, Maya/Istmo VR and Maya VR. The extruded AC catalysts were produced by industrial manufacturing method. The application test of the extruded AC catalyst for ebullating-bed reactor as one of the commercially applicable reactors was carried out at the ebullating-bed pilot plant for 500h. The ebullition of the extruded AC catalyst was successfully traced and confirmed by existing {gamma}-ray density meter. The extruded AC catalyst showed stable performance with less sediment formation at an equivalent conversion by conventional alumina catalyst at commercial ebullating-bed unit. The degradation of the AC catalyst at the aging test was observed to be less than that of the conventional alumina catalyst. Thus, the AC catalyst was confirmed to be effective and suitable for upgrading of heavy oil, especially such heavy oils as Maya, which contains much heavy metals.

Effects of catalyst-support materials on the performance of fuel cells

CSIR Research Space (South Africa)

Ejikeme, PM

2016-07-01

Full Text Available The operating life of a fuel cell is expected to be thousands of hours. One of the critical components of the fuel cell that will allow for such long-life cycle is the catalyst-support material. The support material is expected, amongst others...

Functionalized Natural Carbon-Supported Nanoparticles as Excellent Catalysts for Hydrocarbon Production.

Science.gov (United States)

Sun, Jian; Guo, Lisheng; Ma, Qingxiang; Gao, Xinhua; Yamane, Noriyuki; Xu, Hengyong; Tsubaki, Noritatsu

2017-02-01

We report a one-pot and eco-friendly synthesis of carbon-supported cobalt nanoparticles, achieved by carbonization of waste biomass (rice bran) with a cobalt source. The functionalized biomass provides carbon microspheres as excellent catalyst support, forming a unique interface between hydrophobic and hydrophilic groups. The latter, involving hydroxyl and amino groups, can catch much more active cobalt nanoparticles on surface for Fischer-Tropsch synthesis than chemical carbon. The loading amount of cobalt on the final catalyst is much higher than that prepared with a chemical carbon source, such as glucose. The proposed concept of using a functionalized natural carbon source shows great potential compared with conventional carbon sources, and will be meaningful for other fields concerning carbon support, such as heterogeneous catalysis or electrochemical fields. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of support on the activity of MoVCeZr catalyst for propane ammoxidation reaction

International Nuclear Information System (INIS)

Anita Ramli; Farinaa Md Jamil; Ishak Ahmad

2010-01-01

Mixed metal oxide catalysts based on Mo-V have been known as the most active and selective in the ammoxidation of propane to ACN. A series of MoVCeZr (5 % wt/ wt) supported with MOR, TiO 2 and MgO have been prepared by incipient wetness impregnation method for propane ammoxidation reaction to ACN. The catalyst was calcined in a two step calcination process in static air between 350 - 600 degree Celsius for 10 hour. The surface area and pore size of these catalysts were measured using physical adsorption of nitrogen following Brunauer, Emmet and Teller (BET) equation. The textural and morphological of these catalysts were determined using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). The activities of all catalysts were tested using a fixed-bed reactor with online gas chromatography (GC) at 420 degree Celsius and atmospheric pressure in the presence of 0.5 ml catalyst with composition consisting of 5.8:7:17.4 (propane: ammonia: air) and helium as carrier to give a total flow of 120 ml. Result shows that MoVCeZr support gives a better conversion due to the surface area and pore size characteristic of the catalyst. (author)

VANADIUM ALLOYS

Science.gov (United States)

Smith, K.F.; Van Thyne, R.J.

1959-05-12

This patent deals with vanadium based ternary alloys useful as fuel element jackets. According to the invention the ternary vanadium alloys, prepared in an arc furnace, contain from 2.5 to 15% by weight titanium and from 0.5 to 10% by weight niobium. Characteristics of these alloys are good thermal conductivity, low neutron capture cross section, good corrosion resistance, good welding and fabricating properties, low expansion coefficient, and high strength.

Study of Supported Nickel Catalysts Prepared by Aqueous Hydrazine Method. Hydrogenating Properties and Hydrogen Storage: Support Effect. Silver Additive Effect

International Nuclear Information System (INIS)

Wojcieszak, R.

2006-06-01

We have studied Ni or NiAg nano-particles obtained by the reduction of nickel salts (acetate or nitrate) by hydrazine and deposited by simple or EDTA-double impregnation on various supports (γ-Al 2 O 3 , amorphous or crystallized SiO 2 , Nb 2 O 5 , CeO 2 and carbon). Prepared catalysts were characterized by different methods (XRD, XPS, low temperature adsorption and desorption of N 2 , FTIR and FTIR-Pyridine, TEM, STEM, EDS, H 2 -TPR, H 2 -adsorption, H 2 -TPD, isopropanol decomposition) and tested in the gas phase hydrogenation of benzene or as carbon materials in the hydrogen storage at room temperature and high pressure. The catalysts prepared exhibited better dispersion and activity than classical catalysts. TOF's of NiAg/SiO 2 or Ni/carbon catalysts were similar to Pt catalysts in benzene hydrogenation. Differences in support acidity or preparation method and presence of Ag as metal additive play a crucial role in the chemical reduction of Ni by hydrazine and in the final properties of the materials. Ni/carbon catalysts could store significant amounts of hydrogen at room temperature and high pressure (0.53%/30 bars), probably through the hydrogen spillover effect. (author)

Sol-gel growth of vanadium dioxide

International Nuclear Information System (INIS)

Speck, K.R.

1990-01-01

This thesis examines the chemical reactivity of vanadium (IV) tetrakis(t-butoxide) as a precursor for the sol-gel synthesis of vanadium dioxide. Hydrolysis and condensation of the alkoxide was studied by FTIR spectroscopy. Chemical modification of the vanadium tetraalkoxide by alcohol interchange was studied using 51 V NMR and FTIR. Vanadium dioxide thin films and powders were made from vanadium tetrakis(t-butoxide) by standard sol-gel techniques. Post-deposition heating under nitrogen was necessary to transform amorphous gels into vanadium dioxide. Crystallization of films and powders was studied by FTIR, DSC, TGA, and XRD. Gel-derived vanadium dioxide films undergo a reversible semiconductor-to-metal phase transition near 68C, exhibiting characteristic resistive and spectral changes. The electrical resistance decreased by two to three orders of magnitude and the infrared transmission sharply dropped as the material was cycled through this thermally induced phase transition. The sol-gel method was also used to make doped vanadium dioxide films. Films were doped with tungsten and molybdenum ions to effectively lower the temperature at which the transition occurs

Engineering catalytic activity via ion beam bombardment of catalyst supports for vertically aligned carbon nanotube growth

Science.gov (United States)

Islam, A. E.; Nikolaev, P.; Amama, P. B.; Zakharov, D.; Sargent, G.; Saber, S.; Huffman, D.; Erford, M.; Semiatin, S. L.; Stach, E. A.; Maruyama, B.

2015-09-01

Carbon nanotube growth depends on the catalytic activity of metal nanoparticles on alumina or silica supports. The control on catalytic activity is generally achieved by variations in water concentration, carbon feed, and sample placement on a few types of alumina or silica catalyst supports obtained via thin film deposition. We have recently expanded the choice of catalyst supports by engineering inactive substrates like c-cut sapphire via ion beam bombardment. The deterministic control on the structure and chemistry of catalyst supports obtained by tuning the degree of beam-induced damage have enabled better regulation of the activity of Fe catalysts only in the ion beam bombarded areas and hence enabled controllable super growth of carbon nanotubes. A wide range of surface characterization techniques were used to monitor the catalytically active surface engineered via ion beam bombardment. The proposed method offers a versatile way to control carbon nanotube growth in patterned areas and also enhances the current understanding of the growth process. With the right choice of water concentration, carbon feed and sample placement, engineered catalyst supports may extend the carbon nanotube growth yield to a level that is even higher than the ones reported here, and thus offers promising applications of carbon nanotubes in electronics, heat exchanger, and energy storage.

A 121Sb Moessbauer Study of the Chemical State of Antimony in V-Sb-O Mixed-Oxide Catalysts for the Ammoxidation of Propane

International Nuclear Information System (INIS)

Stievano, L.; Wagner, F. E.; Zanthoff, H. W.; Calogero, S.

2002-01-01

The structural changes of two representative samples of a group of V-Sb-oxide catalysts, a vanadium-rich and an antimony-rich specimen, are investigated by 121 Sb Moessbauer spectroscopy after treatment under propene or hydrogen at 673 K. The as-prepared catalysts contain both Sb(V) and Sb(III) as crystalline and microcrystalline α-Sb 2 O 4 and VSbO 4 , as well as an additional amorphous V 5+ oxide phase. The oxidation state of antimony does not change upon exposure to propene, whereas a partial reduction can be obtained by a more intense reduction under hydrogen. The Moessbauer results indicate that the antimony in VSbO 4 can be reduced more easily than that in α-Sb 2 O 4 , which appears to be more stable. These results are discussed in view of the observed depletion of vanadium at the surface of the catalyst particles under reaction conditions.

Biomass Conversion over Heteropoly Acid Catalysts

KAUST Repository

Zhang, Jizhe

2015-04-01

(Au/Cs2HPW12O40) that enabled the selective conversion of cellobiose to gluconic acid with a very high yield of 96.4% (Chapter II); we realized a direct oxidative conversion of cellulose to glycolic acid (yield of 49.3 %) in a water medium for the first time, by using a phosphomolybdic acid catalyst (chapter III); we found that a vanadium-substituted phosphomolybdic acid catalyst (H4PVMo11O40) is capable of converting various biomass-derived substrates to formic acid and acetic acid with high selectivity, and under optimized reaction conditions, high yield of formic acid (67.8%) can be obtained from cellulose (chapter IV); we discovered that the vanadium-substituted phosphomolybdic acids can also selectively oxidize glycerol, a low-cost by-product of biodiesel, to formic acid, and interestingly this conversion can be performed in highly concentration aqueous solution (glycerol: water = 50: 50), giving rise to exceptionally high conversion efficiency (chapter V). These results reveal that HPAs are useful and suitable catalysts for selective oxidation of biomass, and that the reaction pathway is largely determined by the type of addenda atom in the HPA catalyst. The optimization of the reaction conditions and processes in these systems are also discussed in this thesis.

Effect of Au Precursor and Support on the Catalytic Activity of the Nano-Au-Catalysts for Propane Complete Oxidation

Directory of Open Access Journals (Sweden)

Arshid M. Ali

2015-01-01

Full Text Available Catalytic activity of nano-Au-catalyst(s for the complete propane oxidation was investigated. The results showed that the nature of both Au precursor and support strongly influences catalytic activity of the Au-catalyst(s for the propane oxidation. Oxidation state, size, and dispersion of Au nanoparticles in the Au-catalysts, surface area, crystallinity, phase structure, and redox property of the support are the key aspects for the complete propane oxidation. Among the studied Au-catalysts, the AuHAuCl4-Ce catalyst is found to be the most active catalyst.

Electrochemical characteristics of vanadium redox reactions on porous carbon electrodes for microfluidic fuel cell applications

International Nuclear Information System (INIS)

Lee, Jin Wook; Hong, Jun Ki; Kjeang, Erik

2012-01-01

Microfluidic vanadium redox fuel cells are membraneless and catalyst-free fuel cells comprising a microfluidic channel network with two porous carbon electrodes. The anolyte and catholyte for fuel cell operation are V(II) and V(V) in sulfuric acid based aqueous solution. In the present work, the electrochemical characteristics of the vanadium redox reactions are investigated on commonly used porous carbon paper electrodes and compared to a standard solid graphite electrode as baseline. Half-cell electrochemical impedance spectroscopy is applied to measure the overall ohmic resistance and resistivity of the electrodes. Kinetic parameters for both V(II) and V(V) discharging reactions are extracted from Tafel plots and compared for the different electrodes. Cyclic voltammetry techniques reveal that the redox reactions are irreversible and that the magnitudes of peak current density vary significantly for each electrode. The obtained kinetic parameters for the carbon paper are implemented into a numerical simulation and the results show a good agreement with measured polarization curves from operation of a microfluidic vanadium redox fuel cell employing the same material as flow-through porous electrodes. Recommendations for microfluidic fuel cell design and operation are provided based on the measured trends.

A method for recovery of iron, titanium, and vanadium from vanadium-bearing titanomagnetite

Science.gov (United States)

Zhang, Yi-min; Wang, Li-na; Chen, De-sheng; Wang, Wei-jing; Liu, Ya-hui; Zhao, Hong-xin; Qi, Tao

2018-02-01

An innovative method for recovering valuable elements from vanadium-bearing titanomagnetite is proposed. This method involves two procedures: low-temperature roasting of vanadium-bearing titanomagnetite and water leaching of roasting slag. During the roasting process, the reduction of iron oxides to metallic iron, the sodium oxidation of vanadium oxides to water-soluble sodium vanadate, and the smelting separation of metallic iron and slag were accomplished simultaneously. Optimal roasting conditions for iron/slag separation were achieved with a mixture thickness of 42.5 mm, a roasting temperature of 1200°C, a residence time of 2 h, a molar ratio of C/O of 1.7, and a sodium carbonate addition of 70wt%, as well as with the use of anthracite as a reductant. Under the optimal conditions, 93.67% iron from the raw ore was recovered in the form of iron nugget with 95.44% iron grade. After a water leaching process, 85.61% of the vanadium from the roasting slag was leached, confirming the sodium oxidation of most of the vanadium oxides to water-soluble sodium vanadate during the roasting process. The total recoveries of iron, vanadium, and titanium were 93.67%, 72.68%, and 99.72%, respectively.

Novel geochemistry-inspired method for the deep removal of vanadium from molybdate solution

Energy Technology Data Exchange (ETDEWEB)

Zhang, Jialiang [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing, 100083 (China); Beijing Key Laboratory of Green Recycling and Extraction of Metals, Beijing, 100083 (China); Deng, Yuping; Zhou, Qiuyue; Qin, Peixin; Liu, Yubo [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing, 100083 (China); Wang, Chengyan, E-mail: chywang@yeah.net [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing, 100083 (China)

2017-06-05

Highlights: • A geochemistry-inspired method was developed for removal of V from molybdates. • Magnetic separation of the Fe{sub 3}O{sub 4} adsorbent took 10 s. • Vanadium can be deeply removed in 5 min at pH of 7.0–11.0. • Fe{sub 3}O{sub 4} adsorbent has excellent V selectivity and reusability. • A flowchart is presented for Mo/V separation in the leachate of spent HDS catalyst. - Abstract: Separation of vanadium from molybdates is an essential task for processing the leaching solution of hazardous spent hydrodesulphurization (HDS) catalyst. In this study, the difference in the main naturally occurring mineral forms of Mo and V inspired us to develop a method for the deep removal of V from molybdate solution using Fe{sub 3}O{sub 4} as an adsorbent. First, the adsorbent was synthesized with coprecipitation method, and then it was characterized by XRD, TEM, and VSM. The synthesized material consisted of pure Fe{sub 3}O{sub 4} nanoparticles that exhibited paramagnetic property, with a saturated magnetization of 68.6 emu g{sup −1}. The V removal efficiency was investigated using batch adsorption experiments in varying conditions. Results indicated that V could be deeply removed from various concentrations of molybdate solution at pH of 7.0–11.0 within 5 min. A slight decrease was found in the adsorption ratio after the adsorbent had been reused for 4 cycles. The resulting molybdate solution contained less than 0.02 g L{sup −1} of V, which satisfies the requirement for preparing high-quality products. Finally, a process flowchart is presented for the separation of Mo and V from the leaching solution of spent HDS catalyst, based on the excellent V removal performance and rapid separation rate of the Fe{sub 3}O{sub 4} adsorbent.

An efficient hybrid, nanostructured, epoxidation catalyst: titanium silsesquioxane-polystyrene copolymer supported on SBA-15

NARCIS (Netherlands)

Santen, van R.A.; Zhang, Lei; Abbenhuis, H.C.L.; Gerritsen, G.; Ní Bhriain, N.M.; Magusin, P.C.M.M.; Mezari, B.; Han, W.; Yang, Q.; Li, Can

2007-01-01

A novel interfacial hybrid epoxidation catalyst was designed with a new immobilization method for homogeneous catalysts by coating an inorganic support with an organic polymer film containing active sites. The titanium silsesquioxane (TiPOSS) complex, which contains a single-site titanium active

Porous graphene supported Pt catalysts for proton exchange membrane fuel cells

International Nuclear Information System (INIS)

Cheng, Kun; He, Daping; Peng, Tao; Lv, Haifeng; Pan, Mu; Mu, Shichun

2014-01-01

Graphene nanosheet (GNS) has a remarkably high ratio of surface area to thickness and intense inter-sheet aggregation, which heavily resist mass diffusion in vertical orientation. Here, we establish a fast-speed mass diffusion passage by creating pores in GNS, and the corresponding Pt catalyst (Pt/rPGO) displays 15.5 times mass diffusion rate than that of the pristine GNS supported Pt catalyst (Pt/rGO). Thus, the Pt/rPGO catalyst exhibits 1.5 times increase in Pt mass activity toward oxygen reduction reaction compared with the Pt/rGO. Significantly, after H 2 thermal treatment, the mass activity of the Pt/rPGO further increases to 1.9 times that of the Pt/rGO, and its electrochemical stability is also greatly improved

An oxidation-resistant indium tin oxide catalyst support for proton exchange membrane fuel cells

Energy Technology Data Exchange (ETDEWEB)

Chhina, H.; Campbell, S. [Ballard Power Systems Inc., 9000 Glenlyon Parkway, Burnaby, BC V5J 5J8 (Canada); Kesler, O. [Department of Mechanical Engineering, University of British Columbia, Vancouver, BC, V6T 1Z4 (Canada)

2006-10-27

The oxidation of carbon catalyst supports causes degradation in catalyst performance in proton exchange membrane fuel cells (PEMFCs). Indium tin oxide (ITO) is considered as a candidate for an alternative catalyst support. The electrochemical stability of ITO was studied by use of a rotating disk electrode (RDE). Oxidation cycles between +0.6 and +1.8V were applied to ITO supporting a Pt catalyst. Cyclic voltammograms (CVs) both before and after the oxidation cycles were obtained for Pt on ITO, Hispec 4000 (a commercially available catalyst), and 40wt.% Pt dispersed in-house on Vulcan XC-72R. Pt on ITO showed significantly better electrochemical stability, as determined by the relative change in electrochemically active surface area after cycling. Hydrogen desorption peaks in the CVs existed even after 100 cycles from 0.6 to 1.8V for Pt on ITO. On the other hand, most of the active surface area was lost after 100 cycles of the Hispec 4000 catalyst. The 40wt.% Pt on Vulcan made in-house also lost most of its active area after only 50 cycles. Pt on ITO was significantly more electrochemically stable than both Hispec 4000 and Pt on Vulcan XC-72R. In this study, it was found that the Pt on ITO had average crystallite sizes of 13nm for Pt and 38nm for ITO. Pt on ITO showed extremely high thermal stability, with only {approx}1wt.% loss of material for ITO versus {approx}57wt.% for Hispec 4000 on heating to 1000{sup o}C. The TEM data show Pt clusters dispersed on small crystalline ITO particles. The SEM data show octahedral shaped ITO particles supporting Pt. (author)

Hierarchical nanostructured hollow spherical carbon with mesoporous shell as a unique cathode catalyst support in proton exchange membrane fuel cell.

Science.gov (United States)

Fang, Baizeng; Kim, Jung Ho; Kim, Minsik; Kim, Minwoo; Yu, Jong-Sung

2009-03-07

Hierarchical nanostructured spherical carbon with hollow macroporous core in combination with mesoporous shell has been explored to support Pt cathode catalyst with high metal loading in proton exchange membrane fuel cell (PEMFC). The hollow core-mesoporous shell carbon (HCMSC) has unique structural characteristics such as large specific surface area and mesoporous volume, ensuring uniform dispersion of the supported high loading (60 wt%) Pt nanoparticles with small particle size, and well-developed three-dimensionally interconnected hierarchical porosity network, facilitating fast mass transport. The HCMSC-supported Pt(60 wt%) cathode catalyst has demonstrated markedly enhanced catalytic activity toward oxygen reduction and greatly improved PEMFC polarization performance compared with carbon black Vulcan XC-72 (VC)-supported ones. Furthermore, the HCMSC-supported Pt(40 wt%) or Pt(60 wt%) outperforms the HCMSC-supported Pt(20 wt%) even at a low catalyst loading of 0.2 mg Pt cm(-2) in the cathode, which is completely different from the VC-supported Pt catalysts. The capability of supporting high loading Pt is supposed to accelerate the commercialization of PEMFC due to the anticipated significant reduction in the amount of catalyst support required, diffusion layer thickness and fabricating cost of the supported Pt catalyst electrode.

Enhanced life of proton exchange membrane fuel cell catalysts using perfluorosulfonic acid stabilized carbon support

International Nuclear Information System (INIS)

Cheng Niancai; Mu Shichun; Chen Xiaojing; Lv Haifeng; Pan Mu; Edwards, Peter P.

2011-01-01

We report a new and simple solution to increase life of Pt/C catalysts using the proton-conducting polymer (perfluorosulfonic acid, PFSA) stabilized carbon support (denoted these catalysts as Pt/NFC catalysts) as compared to conventional Pt/C catalysts commonly used in PEM fuel cells. A high catalytic activity of the catalyst is observed by both CV (cyclic voltammetry) and ORR (oxygen reduction reaction) measurements. Especially, our own catalysts have a 60% better life as compared to Pt/C under electrochemically accelerated durability test conditions. The loss rate of electrochemical active area (ECA) for Pt/NFC catalysts is only 0.007 m 2 g -1 cycle -1 , compared to a value of 0.011 m 2 g -1 cycle -1 for Pt/C.

Extraction-complexonometric determination of vanadium(4) in the presence of vanadium(3)

International Nuclear Information System (INIS)

Gordeeva, M.N.; Ryndina, A.M.; Stanevich, T.V.

1976-01-01

The extraction-complexonometric method has been investigated for determining vanadium(4) in the presence of vanadium (3) with high contents of these forms in the solution analyzed. The method of separation of V(4) and V(3) is based on extraction of the ion acetate of vanadium(4) with eriochrome red B(ERCB) and diphenyl quanidinium (DPG) by a mixture of chloroform and isoamyl alcohol (3:1). To control the content of V(4) and V(3) the method of reciprocal complexonometric titration is used (the titrating solution was a solution of thorium nitride, and xylenol orange was a solution of thorium nitride, and xylenol orange was used as metal indicator). Titration has been carried out in an acid solution at pH=2.8. The developed method has been applied to analysis of lithium-zinc spinels containing both forms of vanadium

Utilization of vanadium alloys in the DIII-D Radiative Divertor Program

International Nuclear Information System (INIS)

Smith, J.P.; Johnson, W.R.; Stambaugh, R.D.; Trester, P.W.; Smith, D.; Bloom, E.

1995-10-01

Vanadium alloys are attractive candidate structural materials for fusion power plants because of their potential for minimum environmental impact due to low neutron activation and rapid activation decay. They also possess favorable material properties for operation in a fusion environment. General Atomics (GA), in conjunction with Argonne National Laboratory (ANL) and Oak Ridge National Laboratory (ORNL), has developed a plan for the utilization of vanadium alloys as part of the Radiative Divertor (RD) upgrade for the DIII-D tokamak. The plan will be carried out in conjunction with General Atomics and the Materials Program of the US Department of Energy (DOE). This application of a vanadium alloy will provide a meaningful step in the development of advanced materials for fusion power devices by: (1) developing necessary materials processing technology for the fabrication of large vanadium alloy components, and (2) demonstrating the in-service behavior of a vanadium alloy (V-4Cr-4Ti) in a tokamak environment. The program consists of three phases: first, small vanadium alloy coupon samples will be exposed in DIII-D at positions in the vessel floor and within the pumping plenum region of the existing divertor structure; second, a small vanadium alloy component will be installed in the existing divertor, and third, during the forthcoming Radiative Divertor modification, scheduled for completion in mid-1997, the upper section of the new double-null, slotted divertor will be fabricated from vanadium alloy product forms. This program also includes research and development (R and D) efforts to support fabrication development and to resolve key issues related to environmental effects

Utilization of vanadium alloys in the DIII-D radiative divertor program

International Nuclear Information System (INIS)

Smith, J.P.; Johnson, W.R.; Stambaugh, R.D.; Trester, P.W.; Smith, D.; Bloom, E.

1996-01-01

Vanadium alloys are attractive candidate structural materials for fusion power plants because of their potential for minimum environmental impact due to low neutron activation and rapid activation decay. They also possess favorable material properties for operation in a fusion environment. General Atomics in conjunction with Argonne National Laboratory and Oak Ridge National Laboratory has developed a plan for the utilization of vanadium alloys as part of the radiative divertor upgrade for the DIII-D tokamak. The plan will be carried out in conjunction with General Atomics and the Materials Program of the US Department of Energy. This application of a vanadium alloy will provide a meaningful step in the development of advanced materials for fusion power devices by: (1) developing necessary materials processing technology for the fabrication of large vanadium alloy components and (2) demonstrating the in-service behavior of a vanadium alloy (V-4Cr-4Ti) in a tokamak environment. The program consists of three phases: first, small vanadium alloy coupon samples will be exposed in DIII-D at positions in the vessel floor and within the pumping plenum region of the existing divertor structure; second, a small vanadium alloy component will be installed in the existing divertor, and third, during the forthcoming radiative divertor modification, scheduled for completion in mid-1997, the upper section of the new double-null, slotted divertor will be fabricated from vanadium alloy product forms. This program also includes research and development efforts to support fabrication development and to resolve key issues related to environmental effects. (orig.)

Carbon/H-ZSM-5 composites as supports for bi-functional Fischer-Tropsch synthesis catalysts

NARCIS (Netherlands)

Valero-Romero, M.J.; Sartipi, S.; Sun, X.; Rodríguez-Mirasol, J.; Cordero, T.; Kapteijn, F.; Gascon, J.

2016-01-01

Mesoporous H-ZSM-5–carbon composites, prepared via tetrapropylammonium hydroxide (TPAOH) post treatment of H-ZSM-5 followed by deposition of pyrolytic carbon, have been used as the support for the preparation of Co-based Fischer–Tropsch catalysts. The resulting catalysts display an improved

Reactions of synthesis gas on silica supported transition metal catalysts

Energy Technology Data Exchange (ETDEWEB)

Niemelae, M. [VTT Chemical Technology, Espoo (Finland). Lab. of Industrial Chemistry

1997-12-31

The effect of catalyst precursor and composition on the activation of CO was investigated using CO hydrogenation as a test reaction. The interrelations of preparation, pretreatment, characteristics and activity were clarified. For Co/SiO{sub 2} catalyst, MgO promotion increased the CO adsorption capacity and the hydrogen uptake, although the extent of reduction for cobalt remained the same or decreased. The conversion per active metallic cobalt site consequently increased in conjunction with MgO promotion, while the effect on overall performance per 1 g of catalyst remained moderate. The precursor affected the performance of Co/SiO{sub 2} considerably. CO was more strongly adsorbed on catalysts of carbonyl origin than on those derived from cobalt nitrate, the activity thus being higher. Although the nitrate derived Co/SiO{sub 2} appeared both to retain its activity and to regain its adsorption capacity better than the catalysts of carbonyl origin, the performance of the latter was superior with time on stream. For tetranuclear cluster based Co-Ru and Co-Rh catalysts, rhodium or ruthenium was in contact with the support and cobalt was enriched on top. On Co-Ru/SiO{sub 2} ruthenium enhanced deactivation, and no benefits in activity or oxygenate selectivity were achieved relative to the monometallic catalysts of cluster origin. The Co-Rh/SiO{sub 2} catalysts were also less active than those derived from monometallic clusters, but they exhibited higher selectivities to oxygenated compounds due to the presence of active sites on the perimeter of the cobalt particles located on rhodium. The highest selectivity to oxygenates was achieved by changing the decomposition atmosphere of Rh{sub 4}(CO){sub 12}/SiO{sub 2} from hydrogen to carbon monoxide. The results also showed two types of active sites to be operative in the formation of oxygenates - one for ethanol and another for aldehydes. (orig.) 69 refs.

Catalytic combustion of trichloroethylene over TiO2-SiO2 supported catalysts

NARCIS (Netherlands)

Kulazynski, M.; van Ommen, J.G.; Trawczynski, J.; Walendziewski, J.

2002-01-01

Combustion of trichloroethylene (TCE) on Cr2O3, V2O5, Pt or Pd catalysts supported on TiO2-SiO2 as a carrier has been investigated. It was found that oxide catalysts are very active but their activity quickly diminishes due to loss of the active component, especially at higher reaction temperatures

Preparation and application of zirconium sulfate supported on SAPO-34 molecular sieve as solid acid catalyst for esterification

Energy Technology Data Exchange (ETDEWEB)

Xu, Dongyan, E-mail: xdy0156@sina.com; Ma, Hong; Cheng, Fei

2014-05-01

Graphical abstract: - Highlights: • SAPO-34 supported zirconium sulfate solid acid catalyst was prepared. • Esterification of acetic acid with ethanol can be catalyzed by ZS/SAPO-34. • The hydration of ZS is vital to the acidic property and catalytic performance. • The ZS/SAPO-34 catalyst treated at 200 °C shows good reusability. - Abstract: Zirconium sulfate (ZS) was supported on SAPO-34 molecular sieve by using an incipient wetness impregnation method with zirconium sulfate as the precursor. The as-prepared catalysts were used as solid acid catalyst for esterification reaction of acetic acid with ethanol. The influence of calcination temperature on the acidic property, catalytic activity, and reusability of ZS/SAPO-34 catalysts were mainly investigated. FT-IR, SEM, EDS and TG analysis have been carried out to demonstrate the characteristics of ZS/SAPO-34 catalysts. It was found that the 30 wt%ZS/SAPO-34 catalysts display the property of superacid irrespective of calcination temperature. The ZS/SAPO-34 catalyst treated at 200 °C can enhance the interaction between the supported ZS and SAPO-34 and keep the catalyst remaining substantially active after several reaction cycles. However, further increasing calcination temperature will cause the transfer of ZS from hydrate to anhydrous phase, and thus the decrease of activity.

Preparation and application of zirconium sulfate supported on SAPO-34 molecular sieve as solid acid catalyst for esterification

International Nuclear Information System (INIS)

Xu, Dongyan; Ma, Hong; Cheng, Fei

2014-01-01

Graphical abstract: - Highlights: • SAPO-34 supported zirconium sulfate solid acid catalyst was prepared. • Esterification of acetic acid with ethanol can be catalyzed by ZS/SAPO-34. • The hydration of ZS is vital to the acidic property and catalytic performance. • The ZS/SAPO-34 catalyst treated at 200 °C shows good reusability. - Abstract: Zirconium sulfate (ZS) was supported on SAPO-34 molecular sieve by using an incipient wetness impregnation method with zirconium sulfate as the precursor. The as-prepared catalysts were used as solid acid catalyst for esterification reaction of acetic acid with ethanol. The influence of calcination temperature on the acidic property, catalytic activity, and reusability of ZS/SAPO-34 catalysts were mainly investigated. FT-IR, SEM, EDS and TG analysis have been carried out to demonstrate the characteristics of ZS/SAPO-34 catalysts. It was found that the 30 wt%ZS/SAPO-34 catalysts display the property of superacid irrespective of calcination temperature. The ZS/SAPO-34 catalyst treated at 200 °C can enhance the interaction between the supported ZS and SAPO-34 and keep the catalyst remaining substantially active after several reaction cycles. However, further increasing calcination temperature will cause the transfer of ZS from hydrate to anhydrous phase, and thus the decrease of activity

Catalytic performance of activated carbon supported cobalt catalyst for CO2 reforming of CH4.

Science.gov (United States)

Zhang, Guojie; Su, Aiting; Du, Yannian; Qu, Jiangwen; Xu, Ying

2014-11-01

Syngas production by CO2 reforming of CH4 in a fixed bed reactor was investigated over a series of activated carbon (AC) supported Co catalysts as a function of Co loading (between 15 and 30wt.%) and calcination temperature (Tc=300, 400 or 500°C). The catalytic performance was assessed through CH4 and CO2 conversions and long-term stability. XRD and SEM were used to characterize the catalysts. It was found that the stability of Co/AC catalysts was strongly dependent on the Co loading and calcination temperature. For the loadings (25wt.% for Tc=300°C), stable activities have been achieved. The loading of excess Co (>wt.% 25) causes negative effects not only on the performance of the catalysts but also on the support surface properties. In addition, the experiment showed that ultrasound can enhance and promote dispersion of the active metal on the carrier, thus improving the catalytic performance of the catalyst. The catalyst activity can be long-term stably maintained, and no obvious deactivation has been observed in the first 2700min. After analyzing the characteristics, a reaction mechanism for CO2 reforming of CH4 over Co/AC catalyst was proposed. Copyright © 2014 Elsevier Inc. All rights reserved.

Extended X-ray absorption fine structure (EXAFS) studies of supported catalysts

International Nuclear Information System (INIS)

Joyner, R.W.

1979-01-01

Since the rebirth of interest in extended X-ray absorption fine structure there have been several studies of systems of catalytic interest. This note is a preliminary account of an investigation of supported platinum catalysts and NiO/Al 2 O 3 catalysts. Experiments were performed on pressed disc samples at the DESY synchrotron, Hamburg, using the EXAFS spectrometer. The synchrotron operated at 7 GeV energy with a circulating current of approximately 4 mA; spectrum accumulation time was typically 45 minutes. (author)

Electro-oxidation of Ethanol on Carbon Supported PtSn and PtSnNi Catalysts

Directory of Open Access Journals (Sweden)

Nur Hidayati

2016-03-01

Full Text Available Even though platinum is known as an active electro-catalyst for ethanol oxidation at low temperatures (< 100 oC, choosing the electrode material for ethanol electro-oxidation is a crucial issue. It is due to its property which easily poisoned by a strong adsorbed species such as CO. PtSn-based electro-catalysts have been identified as better catalysts for ethanol electro-oxidation. The third material is supposed to improved binary catalysts performance. This work presents a study of the ethanol electro-oxidation on carbon supported Pt-Sn and Pt-Sn-Ni catalysts. These catalysts were prepared by alcohol reduction. Nano-particles with diameters between 2.5-5.0 nm were obtained. The peak of (220 crystalline face centred cubic (fcc Pt phase for PtSn and PtSnNi alloys was repositioned due to the presence of Sn and/or Ni in the alloy. Furthermore, the modification of Pt with Sn and SnNi improved ethanol and CO electro-oxidation. Copyright © 2016 BCREC GROUP. All rights reserved Received: 10th November 2015; Revised: 1st February 2016; Accepted: 1st February 2016 How to Cite: Hidayati, N., Scott, K. (2016. Electro-oxidation of Ethanol on Carbon Supported PtSn and PtSnNi Catalysts. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (1: 10-20. (doi:10.9767/bcrec.11.1.394.10-20 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.11.1.394.10-20

Hydrogen recombiner catalyst test supporting data

International Nuclear Information System (INIS)

Britton, M.D.

1995-01-01

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

Mesoporous Silica Supported Au Nanoparticles with Controlled Size as Efficient Heterogeneous Catalyst for Aerobic Oxidation of Alcohols

Directory of Open Access Journals (Sweden)

Xuefeng Chu

2015-01-01

Full Text Available A series of Au catalysts with different sizes were synthesized and employed on amine group functionalized ordered mesoporous silica solid supports as catalyst for the aerobic oxidation of various alcohols. The mesoporous silica of MCM-41 supported Au nanoparticles (Au-1 exhibited the smallest particle size at ~1.8 nm with superior catalytic activities owing to the confinement effect of the mesoporous channels. Au-1 catalyst is also very stable and reusable under aerobic condition. Therefore, this presented work would obviously provide us a platform for synthesizing more size-controlled metal catalysts to improve the catalytic performances.

Enhanced life of proton exchange membrane fuel cell catalysts using perfluorosulfonic acid stabilized carbon support

Energy Technology Data Exchange (ETDEWEB)

Cheng Niancai [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 430070 (China); Mu Shichun, E-mail: msc@whut.edu.c [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 430070 (China); Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, OX1 3QR (United Kingdom); Chen Xiaojing; Lv Haifeng; Pan Mu [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 430070 (China); Edwards, Peter P. [Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, OX1 3QR (United Kingdom)

2011-02-01

We report a new and simple solution to increase life of Pt/C catalysts using the proton-conducting polymer (perfluorosulfonic acid, PFSA) stabilized carbon support (denoted these catalysts as Pt/NFC catalysts) as compared to conventional Pt/C catalysts commonly used in PEM fuel cells. A high catalytic activity of the catalyst is observed by both CV (cyclic voltammetry) and ORR (oxygen reduction reaction) measurements. Especially, our own catalysts have a 60% better life as compared to Pt/C under electrochemically accelerated durability test conditions. The loss rate of electrochemical active area (ECA) for Pt/NFC catalysts is only 0.007 m{sup 2} g{sup -1} cycle{sup -1}, compared to a value of 0.011 m{sup 2} g{sup -1} cycle{sup -1} for Pt/C.

Redox Equilibria in SO2 Oxidation Catalysts

DEFF Research Database (Denmark)

Rasmussen, Søren Birk; Eriksen, Kim Michael; Boghosian, Soghomon

1999-01-01

been carried out regarding the complex and compound formation of V(V) and the formation of V(IV) and V(III) compounds with low solubility causing catalyst deactivation. However, the redox chemistry of vanadium and the complex formation of V(IV) is much less investigated and further information...... on these subjects in pyrosulfate melts is needed to obtain a deeper understanding of the reaction mechanism. The present paper describes our efforts so far to study the V(IV) chemistry using especially spectroscopic and electrochemical methods....

Extraction of Vanadium from Vanadium Slag Via Non-salt Roasting and Ammonium Oxalate Leaching

Science.gov (United States)

Li, Meng; Du, Hao; Zheng, Shili; Wang, Shaona; Zhang, Yang; Liu, Biao; Dreisinger, David Bruce; Zhang, Yi

2017-10-01

A clean method featuring non-salt roasting followed by (NH4)2C2O4 leaching to recover vanadium from vanadium slag was proposed. The carcinogenic Cr6+ compounds and exhaust gases were avoided, and the water generated from vanadate precipitation may be recycled and reused in this new leaching process. The leaching residues may be easily used by a blast furnace. Moreover, (NH4)2C2O4 solution was used as a leaching medium to avoid expensive and complicated ammonium controlling operations as a result of the stability of (NH4)2C2O4 at a high temperature. The transformation mechanisms of vanadium- and chromium-bearing phases were systematically investigated by x-ray diffraction analysis and scanning electron microscopy with energy-disperse x-ray spectrometry, respectively. In addition, the effects of oxygen concentration, roasting temperature, and holding time on vanadium recovery were investigated. Finally, the effects of leaching variables on the vanadium leaching rate were also examined.

Pd nanoparticles Supported on Cellulose as a catalyst for vanillin conversion in aqueous media.

Science.gov (United States)

Li, Dan-Dan; Zhang, Jia-Wei; Cai, Chun

2018-05-17

Palladium nanoparticles were firstly anchored on modified biopolymer as an efficient catalyst for biofuel upgradation. Fluorinated compounds was grafted onto cellulose to obtain amphiphilic supports for on water reactions. Pd catalyst was prepared by straightforward deposition of metal nanoparticles on modified cellulose. The catalyst exhibited excellent catalytic activity and selectivity in hydrodeoxygenation of vanillin (a typical model compound of lignin) to 2-methoxy-4-methylphenol under atmospheric hydrogen pressure in neat water without any other additives under mild conditions.

Oxidation of CO and Methanol on Pd-Ni Catalysts Supported on Different Chemically-Treated Carbon Nanofibers

Directory of Open Access Journals (Sweden)

Juan Carlos Calderón

2016-10-01

Full Text Available In this work, palladium-nickel nanoparticles supported on carbon nanofibers were synthesized, with metal contents close to 25 wt % and Pd:Ni atomic ratios near to 1:2. These catalysts were previously studied in order to determine their activity toward the oxygen reduction reaction. Before the deposition of metals, the carbon nanofibers were chemically treated in order to generate oxygen and nitrogen groups on their surface. Transmission electron microscopy analysis (TEM images revealed particle diameters between 3 and 4 nm, overcoming the sizes observed for the nanoparticles supported on carbon black (catalyst Pd-Ni CB 1:2. From the CO oxidation at different temperatures, the activation energy Eact for this reaction was determined. These values indicated a high tolerance of the catalysts toward the CO poisoning, especially in the case of the catalysts supported on the non-chemically treated carbon nanofibers. On the other hand, apparent activation energy Eap for the methanol oxidation was also determined finding—as a rate determining step—the COads diffusion to the OHads for the catalysts supported on carbon nanofibers. The results here presented showed that the surface functional groups only play a role in the obtaining of lower particle sizes, which is an important factor in the obtaining of low CO oxidation activation energies.

Methanol-Tolerant Platinum-Palladium Catalyst Supported on Nitrogen-Doped Carbon Nanofiber for High Concentration Direct Methanol Fuel Cells.

Science.gov (United States)

Kim, Jiyoung; Jang, Jin-Sung; Peck, Dong-Hyun; Lee, Byungrok; Yoon, Seong-Ho; Jung, Doo-Hwan

2016-08-15

Pt-Pd catalyst supported on nitrogen-doped carbon nanofiber (N-CNF) was prepared and evaluated as a cathode electrode of the direct methanol fuel cell (DMFC). The N-CNF, which was directly synthesized by the catalytic chemical vapor deposition from acetonitrile at 640 °C, was verified as having a change of electrochemical surface properties such as oxygen reduction reaction (ORR) activities and the electrochemical double layer compared with common carbon black (CB). To attain the competitive oxygen reduction reaction activity with methanol tolerance, the Pt and Pd metals were supported on the CB or the N-CNF. The physical and electrochemical characteristics of the N-CNF-supported Pt-Pd catalyst were examined and compared with catalyst supported on the CB. In addition, DMFC single cells using these catalysts as the cathode electrode were applied to obtain I-V polarization curves and constant current operating performances with high-concentration methanol as the fuel. Pt-Pd catalysts had obvious ORR activity even in the presence of methanol. The higher power density was obtained at all the methanol concentrations when it applied to the membrane electrode assembly (MEA) of the DMFC. When the N-CNF is used as the catalyst support material, a better performance with high-concentration methanol is expected.

Methanol-Tolerant Platinum-Palladium Catalyst Supported on Nitrogen-Doped Carbon Nanofiber for High Concentration Direct Methanol Fuel Cells

Directory of Open Access Journals (Sweden)

Jiyoung Kim

2016-08-01

Full Text Available Pt-Pd catalyst supported on nitrogen-doped carbon nanofiber (N-CNF was prepared and evaluated as a cathode electrode of the direct methanol fuel cell (DMFC. The N-CNF, which was directly synthesized by the catalytic chemical vapor deposition from acetonitrile at 640 °C, was verified as having a change of electrochemical surface properties such as oxygen reduction reaction (ORR activities and the electrochemical double layer compared with common carbon black (CB. To attain the competitive oxygen reduction reaction activity with methanol tolerance, the Pt and Pd metals were supported on the CB or the N-CNF. The physical and electrochemical characteristics of the N-CNF–supported Pt-Pd catalyst were examined and compared with catalyst supported on the CB. In addition, DMFC single cells using these catalysts as the cathode electrode were applied to obtain I-V polarization curves and constant current operating performances with high-concentration methanol as the fuel. Pt-Pd catalysts had obvious ORR activity even in the presence of methanol. The higher power density was obtained at all the methanol concentrations when it applied to the membrane electrode assembly (MEA of the DMFC. When the N-CNF is used as the catalyst support material, a better performance with high-concentration methanol is expected.

Catalytic hydrolysis of ammonia borane for hydrogen generation using cobalt nanocluster catalyst supported on polydopamine functionalized multiwalled carbon nanotube

International Nuclear Information System (INIS)

Arthur, Ernest Evans; Li, Fang; Momade, Francis W.Y.; Kim, Hern

2014-01-01

Hydrogen was generated from ammonia borane complex by hydrolysis using cobalt nanocluster catalyst supported on polydopamine functionalized MWCNTs (multi-walled carbon nanotubes). The impregnation-chemical reduction method was used for the preparation of the supported catalyst. The nanocluster catalyst support was formed by in-situ oxidative polymerization of dopamine on the MWCNTs in alkaline solution at room temperature. The structural and physical–chemical properties of the nanocluster catalyst were characterized by FT-IR (Fourier transform infrared spectroscopy), EDX (energy-dispersive X-ray spectroscopy), SEM (scanning electron microscope), XRD (X-ray diffraction) and TEM (transmission electron microscopy). The nanocluster catalyst showed good catalytic activity for the hydrogen generation from aqueous ammonia borane complex. A reusability test to determine the practical usage of the catalyst was also investigated. The result revealed that the catalyst maintained an appreciable catalytic performance and stability in terms of its reusability after three cycle of reuse for the hydrolysis reaction. Also, the activation energy for the hydrolysis of ammonia borane complex was estimated to be 50.41 kJmol −1 , which is lower than the values of some of the reported catalyst. The catalyst can be considered as a promising candidate in developing highly efficient portable hydrogen generation systems such as PEMFC (proton exchange membrane fuel cells). - Highlights: • Co/Pdop-o-MWCNT (Pdop functionalized MWCNT supported cobalt nanocluster) catalyst was synthesized for hydrogen generation. • It is an active catalyst for hydrogen generation via hydrolysis of ammonia borane. • It showed good stability in terms of reusability for the hydrogen generation

Mercury Oxidation over Selective Catalytic Reduction (SCR) Catalysts - Ph.d. thesis Karin Madsen

DEFF Research Database (Denmark)

Madsen, Karin

The vanadium-based SCR catalyst used for NOx-control promotes the oxidation of elemental mercury Hg0 to Hg2+ in flue gases from coal-fired power plants. Hg2+ is water soluble and can effectively be captured in a wet scrubber. This means that the combination of an SCR with a wet FGD can offer an e...

The role of support and promoter on the oxidation of sulfur dioxide using platinum based catalysts

DEFF Research Database (Denmark)

Koutsopoulos, Sotiris; Rasmussen, Søren Birk; Eriksen, Kim Michael

2006-01-01

The catalytic oxidation of SO2 to SO3 was studied over platinum based catalysts in the absence and the presence of dopants. The active metal was supported on silica gel or titania (anatase) by impregnation. The activities of the silica supported catalysts were found to follow the order PtRh/SiO2 ...

Metathesis of cardanol over Ru catalysts supported on mesoporousmolecular sieve SBA-15

Czech Academy of Sciences Publication Activity Database

Shinde, Tushar; Varga, Vojtěch; Polášek, Miroslav; Horáček, Michal; Žilková, Naděžda; Balcar, Hynek

2014-01-01

Roč. 478, MAY 2014 (2014), s. 138-145 ISSN 0926-860X R&D Projects: GA ČR(CZ) GAP106/12/0189 Institutional support: RVO:61388955 Keywords : cardanol * metathesis * supported catalysts Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.942, year: 2014

Partial oxidation of n- and i-pentane over promoted vanadium-phosphorus oxide catalysts

Energy Technology Data Exchange (ETDEWEB)

Zazhigalov, V.A.; Mikhajluk, B.D.; Komashko, G.A. [AN Ukrainskoj SSR, Kiev (Ukraine). Inst. Fizicheskoj Khimii

1998-12-31

It is known, that the cost of raw materials for catalytic oxidation processes is about 60% of the product price. Cheap initial compounds to produce variety of products and to replace olefins and aromatic hydrocarbons are paraffins. That is why catalytic systems which could be possibly rather efficient in selective oxidation of paraffin hydrocarbons are under very close investigation now. One of such processes in n-pentane oxidation. The obtained results on n-pentane oxidation over VPO catalysts were quite encouraging in respect of possible reach high selectivity and yield of phthalic anhydride. However, in our work it was shown that the main product of n-pentane oxidation in the presence of VPO catalytic system as well as VPMeO was maleic anhydride. Some later our results were confirmed in, where to grow the selectivity towards phthalic anhydride the Co-additive was introduced. On the basis of the proposal made before on the mechanism of paraffins conversion over the vanadyl pyrophosphate surface with their activation at the first and fourth carbon atoms, we assumed possible methylmaleic (citraconic) anhydride forming at n- and i-pentane oxidation. This assumption has been recently supported by both our and other researchers` experimental results. In it was also hypothized possible mechanistic features for phthalic anhydride forming from n-pentane. The present work deals with the results of n- and i-pentane oxidation over VPO catalysts promoted with Bi, Cs, Te, Zr. (orig.)

Hydrogen production by steam reforming of liquefied natural gas (LNG) over nickel catalysts supported on cationic surfactant-templated mesoporous aluminas

Science.gov (United States)

Seo, Jeong Gil; Youn, Min Hye; Park, Sunyoung; Jung, Ji Chul; Kim, Pil; Chung, Jin Suk; Song, In Kyu

Two types of mesoporous γ-aluminas (denoted as A-A and A-S) are prepared by a hydrothermal method under different basic conditions using cationic surfactant (cetyltrimethylammonium bromide, CTAB) as a templating agent. A-A and A-S are synthesized in a medium of ammonia solution and sodium hydroxide solution, respectively. Ni/γ-Al 2O 3 catalysts (Ni/A-A and Ni/A-S) are then prepared by an impregnation method, and are applied to hydrogen production by steam reforming of liquefied natural gas (LNG). The effect of a mesoporous γ-Al 2O 3 support on the catalytic performance of Ni/γ-Al 2O 3 is investigated. The identity of basic solution strongly affects the physical properties of the A-A and A-S supports. The high surface-area of the mesoporous γ-aluminas and the strong metal-support interaction of supported catalysts greatly enhance the dispersion of nickel species on the catalyst surface. The well-developed mesopores of the Ni/A-A and Ni/A-S catalysts prohibit the polymerization of carbon species on the catalyst surface during the reaction. In the steam reforming of LNG, both Ni/A-A and Ni/A-S catalysts give better catalytic performance than the nickel catalyst supported on commercial γ-Al 2O 3 (Ni/A-C). In addition, the Ni/A-A catalyst is superior to the Ni/A-S catalyst. The relatively strong metal-support interaction of Ni/A-A catalyst effectively suppresses the sintering of metallic nickel and the carbon deposition in the steam reforming of LNG. The large pores of the Ni/A-A catalyst also play an important role in enhancing internal mass transfer during the reaction.

Isotopic exchange between deuterium and neohexane on supported platinum and palladium catalysts

International Nuclear Information System (INIS)

Eskinazi, V.

1979-01-01

The isotopic exchange reaction between neohexane and deuterium on supported Pt/SiO 2 and Pd/SiO 2 catalysts has been investigated in the temperature range 86.5 to 110 0 C. Rates of exchange were studied as functions of percentage of metal atoms exposed, the conditions of catalyst pretreatment, and the reaction temperature. The rates of exchange were not strongly dependent upon percentage exposed; however, the relative yields of d 1 through d 5 in the ethyl moiety or neohexane were dependent on the percentage metal atoms exposed. The Pt/SiO 2 catalysts were found to be more active for exchange than the Pd/SiO 2 catalysts by an order of magnitude. Both the turnover frequencies and the exchange pattern were observed to be influenced by the pretreatment of the catalyst. Maxima in the exchange pattern occurred at d 3 and d 5 in the case of Pt/SiO 2 and at d 5 only in the case of the Pd/SiO 2 catalysts. In order to account for the d 3 maximum observed for Pt catalysts, some extension of the Horiuti-Polanyi mechanism is required. Mechanisms by which the d 3 species might be formed are proposed and discussed. On Pd/SiO 2 catalysts exchange occurs preferentially in the ethyl substituent of the quaternary carbon atom rather than on the three methyl substituents of the quaternary carbon atom. Such preference is not observed on Pt/SiO 2 catalysts; in fact, in some cases, this preference is reversed. Whenever exchange occurs in the three methyl substituents, mostly the d 1 product is obtained. For Pt/SiO 2 catalysts, the exchange pattern appears to be influenced by steric effects, but the data suggest that factors other than steric effects are important on Pd

Effects of dietary vanadium in mallard ducks

Science.gov (United States)

White, D.H.; Dieter, M.P.

1978-01-01

Adult mallard ducks fed 0, 1, 10, or 100 ppm vanadyl sulfate in the diet were sacrificed after 12 wk on treatment; tissues were analyzed for vanadium. No birds died during the study and body weights did not change. Vanadium accumulated to higher concentrations in the bone and liver than in other tissues. Concentrations in bones of hens were five times those in bones of drakes, suggesting an interaction between vanadium and calcium mobilization in laying hens. Vanadium concentrations in most tissues were significantly correlated and increased with treatment level. Lipid metabolism was altered in laying hens fed 100 ppm vanadium. Very little vanadium accumulated in the eggs of laying hens.

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.

Rational design of Mg-Al mixed oxide-supported bimetallic catalysts for dry reforming of methane

Energy Technology Data Exchange (ETDEWEB)

Tsyganok, Andrey I. [Centre for Catalysis Research and Innovation, Department of Chemistry, University of Ottawa, D' Iorio Hall, 10 Marie Curie Street, Ottawa, Ont. (Canada); Inaba, Mieko [Natural Gas Technology Development Team, Teikoku Oil Co., 9-23-30 Kitakarasuyama, Setagaya-ku, Tokyo 157-0061 (Japan); Tsunoda, Tatsuo; Uchida, Kunio; Suzuki, Kunio; Hayakawa, Takashi [Institute for Materials and Chemical Process, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba 305-8565 (Japan); Takehira, Katsuomi [Department of Applied Chemistry, Faculty of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527 (Japan)

2005-09-18

A novel synthetic strategy for preparing bimetallic Ru-M (M=Cr, Fe, Co, Ni and Cu) catalysts, supported on Mg-Al mixed oxide, has been introduced. It was based on a 'memory effect', i.e. on the ability of Mg-Al mixed oxide to reconstruct a layered structure upon rehydration with an aqueous solution. By repeated calcinations-rehydration cycles, layered double hydroxide (LDH) precursors of catalysts containing two different metals were synthesized. Bimetallic catalysts were then generated (1) in situ from LDH under methane reforming reaction conditions and (2) from mixed metal oxides obtained by preliminary LDH calcination. Among all the LDH-derived catalysts, a Ru{sup 0.1%}-Ni{sup 5.0%}/MgAlO{sub x} sample revealed the highest activity and selectivity to syngas, a suitable durability and a low coking capacity. A promoting effect of ruthenium on catalytic function of supported nickel was demonstrated. Preliminary LDH calcination was shown to markedly affect the catalytic activity of the derived catalysts and especially their coking properties.

Session 4: High-throughput screening of supported catalysts for CO{sub x}-free hydrogen production from ammonia

Energy Technology Data Exchange (ETDEWEB)

Hongchao, Liu; Hua, Wang; Zhongmin, Liu; Jianghan, Shen [Natural Gas Utilization and Applied Catalysis Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, P. R. (China)

2004-07-01

In this paper, we used a multi-stream mass spectrometer screening (MSMSS) technique and a multi-stream reactor to select promising candidates from supported transition metal catalyst library, and then combinatorially nitrided and tested silica and SAB-15 supported Mo catalysts for hydrogen production from ammonia. (authors)

Metathesis of cardanol over ammonium tagged Hoveyda-Grubbs type catalyst supported on SBA-15

Czech Academy of Sciences Publication Activity Database

Balcar, Hynek; Žilková, Naděžda; Kubů, Martin; Polášek, Miroslav; Zedník, J.

2018-01-01

Roč. 304, APR 2018 (2018), s. 127-134 ISSN 0920-5861 R&D Projects: GA ČR GA17-01440S Institutional support: RVO:61388955 Keywords : Cardanol * Flow chemistry * Hoveyda-Grubbs type catalyst * Immobilized catalyst Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 4.636, year: 2016

Process for hydroprocessing heavy oils utilizing sepiolite-based catalysts

Energy Technology Data Exchange (ETDEWEB)

Auden, C.A.; Yan, T.-Y.

1986-04-15

A process is described for demetallizing and desulfurizing a hydrocarbon oil comprising contacting the hydrocarbon oil in the presence of hydrogen and a sepiolite-based catalyst composition under conditions of pressure and temperature sufficient to effect demetallization and desulfurization. The sepiolite-based catalyst composition has been prepared by first contacting the sepiolite with an aqueous solution of a first metal salt, then contacting the resultant metal ion-exchanged sepiolite with an aqueous solution of a compound of a second metal selected from the group consisting of molybdenum, tungsten and vanadium, and finally contacting the resultant metal-exchanged sepiolite product with an aqueous solution of a magnesium compound, thereby effecting a magnesium ion-exchange with the metal-exchanged sepiolite product and neutralizing acid sites on the sepiolite product.

Hydrocracking of α-Cellulose Using Co, Ni, and Pd Supported on Mordenite Catalysts

Directory of Open Access Journals (Sweden)

Wega Trisunaryanti

2018-02-01

Full Text Available Hydrocracking of α-cellulose has been conducted in a semi-batch reactor at 400, 450, and 500 °C with hydrogen flow (30 mL/min. for 4 h. Mordenite (MOR and Co, Ni and Pd metal supported on the MOR were used as solid catalysts. The catalysts were characterized using X-ray Diffractometer (XRD, Fourier Transform Infrared (FTIR spectroscopy, and Scanning Electron Microscopy (SEM to evaluate the physical-chemical properties. Energy Dispersive X-ray (EDX and Inductively Coupled Plasma (ICP were used to analyze the amount of metal impregnated on the catalysts. The liquid product was analyzed using Gas Chromatograph-Mass Spectroscopy (GC-MS. Thermal hydrocracking was also conducted at 450 °C with the amount of liquid product was 37.86 wt.%. The highest liquid conversion obtained by mordenite catalyst was 94.66 wt.% at 450 °C and the highest liquid conversion (98.08 wt.% was reached by Pd/MOR catalyst at 400 °C.

Efficient Separation and Extraction of Vanadium and Chromium in High Chromium Vanadium Slag by Selective Two-Stage Roasting-Leaching

Science.gov (United States)

Wen, Jing; Jiang, Tao; Xu, Yingzhe; Liu, Jiayi; Xue, Xiangxin

2018-04-01

Vanadium and chromium are important rare metals, leading to a focus on high chromium vanadium slag (HCVS) as a potential raw material to extract vanadium and chromium in China. In this work, a novel method based on selective two-stage roasting-leaching was proposed to separate and extract vanadium and chromium efficiently in HCVS. XRD, FT-IR, and SEM were utilized to analyze the phase evolutions and microstructure during the whole process. Calcification roasting, which can calcify vanadium selectively using thermodynamics, was carried out in the first roasting stage to transfer vanadium into acid-soluble vanadate and leave chromium in the leaching residue as (Fe0.6Cr0.4)2O3 after H2SO4 leaching. When HCVS and CaO were mixed in the molar ratio CaO/V2O3 (n(CaO)/n(V2O3)) of 0.5 to 1.25, around 90 pct vanadium and less than 1 pct chromium were extracted in the first leaching liquid, thus achieving the separation of vanadium and chromium. In the second roasting stage, sodium salt, which combines with chromium easily, was added to the first leaching residue to extract chromium and 95.16 pct chromium was extracted under the optimal conditions. The total vanadium and chromium leaching rates were above 95 pct, achieving the efficient separation and extraction of vanadium and chromium. The established method provides a new technique to separate vanadium and chromium during roasting rather than in the liquid form, which is useful for the comprehensive application of HCVS.

Efficient Separation and Extraction of Vanadium and Chromium in High Chromium Vanadium Slag by Selective Two-Stage Roasting-Leaching

Science.gov (United States)

Wen, Jing; Jiang, Tao; Xu, Yingzhe; Liu, Jiayi; Xue, Xiangxin

2018-06-01

Vanadium and chromium are important rare metals, leading to a focus on high chromium vanadium slag (HCVS) as a potential raw material to extract vanadium and chromium in China. In this work, a novel method based on selective two-stage roasting-leaching was proposed to separate and extract vanadium and chromium efficiently in HCVS. XRD, FT-IR, and SEM were utilized to analyze the phase evolutions and microstructure during the whole process. Calcification roasting, which can calcify vanadium selectively using thermodynamics, was carried out in the first roasting stage to transfer vanadium into acid-soluble vanadate and leave chromium in the leaching residue as (Fe0.6Cr0.4)2O3 after H2SO4 leaching. When HCVS and CaO were mixed in the molar ratio CaO/V2O3 (n(CaO)/n(V2O3)) of 0.5 to 1.25, around 90 pct vanadium and less than 1 pct chromium were extracted in the first leaching liquid, thus achieving the separation of vanadium and chromium. In the second roasting stage, sodium salt, which combines with chromium easily, was added to the first leaching residue to extract chromium and 95.16 pct chromium was extracted under the optimal conditions. The total vanadium and chromium leaching rates were above 95 pct, achieving the efficient separation and extraction of vanadium and chromium. The established method provides a new technique to separate vanadium and chromium during roasting rather than in the liquid form, which is useful for the comprehensive application of HCVS.

Preparation of SnO{sub 2}-CNTs supported Pt catalysts and their electrocatalytic properties for ethanol oxidation

Energy Technology Data Exchange (ETDEWEB)

Pang, H.L.; Lu, J.P. [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Chen, J.H. [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China)], E-mail: chenjinhua@hnu.cn; Huang, C.T.; Liu, B.; Zhang, X.H. [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China)

2009-03-30

SnO{sub 2}-carbon nanotubes (CNTs) composites were prepared by sol-gel method, and characterized by scanning electron microscopy and X-ray diffraction. Due to high stability in diluted acidic solution, SnO{sub 2}-CNTs composites were selected as the catalyst support and second catalyst for ethanol electrooxidation. The electrocatalytic properties of the SnO{sub 2}-CNTs supported platinum (Pt) catalyst (Pt/SnO{sub 2}-CNTs) for ethanol oxidation have been investigated by typical electrochemical methods. Under the same mass loading of Pt, the Pt/SnO{sub 2}-CNTs catalyst shows higher electrocatalytic activity and better long-term cycle stability than Pt/SnO{sub 2} catalyst. Additionally, the effect of the mass ratio of CNTs to SnO{sub 2} on the electrocatalytic activity of the electrode for ethanol oxidation was investigated, and the optimum mass ratio of CNTs to SnO{sub 2} in the Pt/SnO{sub 2}-CNTs catalyst is 1/6.3.