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Showing papers on "Catalyst support published in 2001"


Journal ArticleDOI
TL;DR: In this article, a thorough comparison of gold catalysts on different support materials as well as activity measurements for Au on mixed oxides (Au/Fe2O3·MgO) reveal enhanced CO oxidation rates for a group of active support materials (Fe 2O3, TiO2, NiOx, CoOx).

1,071 citations


Journal ArticleDOI
TL;DR: In this paper, different procedures are discussed on how to put a coat layer of a catalyst support material like alumina, silica, or carbon on a monolith body by either filling the pores in that support or by putting a layer on that support.
Abstract: Monolithic catalysts can be attractive replacements for conventional catalysts in randomly packed beds or slurry reactors. The conventional procedures for preparing catalysts, however, cannot simply be applied to monolithic catalysts. Different procedures are discussed on how to put a coat layer of a catalyst support material like alumina, silica, or carbon on a monolith body by either filling the pores in that support or by putting a layer on that support. Different methods to apply an active phase to the support are discussed as well. Finally, methods to convert ready-made catalysts into monolithic catalysts are presented.

510 citations


Journal ArticleDOI
TL;DR: In this paper, a review paper deals with proven and potential applications of mesoporous molecular sieves in catalysis, and is divided into two parts, respectively, dedicated to the design of solid catalysts and catalyst supports and to some relevant examples of catalytic processes.
Abstract: This review paper deals with proven and potential applications of mesoporous molecular sieves in catalysis. In addition to introduction and conclusion, the text is divided into two parts, respectively, dedicated to the design of solid catalysts and catalyst supports and to some relevant examples of catalytic processes.

440 citations


Journal ArticleDOI
TL;DR: In this paper, the deactivation of supported copper metal catalysts in hydrogenation reactions has been investigated and the best understood are Cu/ZnO formulations that have improved sulphur resistance due to formation of thermodynamically stable ZnS.
Abstract: Laboratory and industrial results are used to elucidate the general features of the deactivation of supported copper metal catalysts in hydrogenation reactions. Hydrogenations with copper catalysts are milder than with their nickel or platinum counterparts, and they have selectivities that are exploited commercially. They are used in single stream plants for production of hydrogen via the low-temperature water shift gas reaction, and for methanol manufacture from synthesis gas, and also in hydrogenation of speciality organic compounds. Common catalyst types are based on Cu/Cr 2 O 3 (copper chromite) or Cu/ZnO formulations that contain stabilisers and promoters such as alkaline earth oxides and Al 2 O 3 . These have several roles, including inhibition of sintering, and poison traps that prevent poisoning of the active metal surface. The best understood are Cu/ZnO formulations that have improved sulphur resistance due to formation of thermodynamically stable ZnS. Copper catalysts are susceptible to thermal sintering via a surface migration process and this is markedly accelerated by the presence of even traces of chloride. Care must be, therefore, taken to eliminate halides from copper catalysts during manufacture, and from the reactants during use. Operating temperatures must be restricted, usually to below 300°C when catalyst longevity is important with large catalyst volumes. Water can soften some Cu/ZnO formulations during use, and cause particle breakage that leads to high-pressure drop and maldistribution of flow through large catalyst beds and impaired performance. Commercial copper catalysts are not acidic, and since they operate under mild conditions, carbon deposition (coking) is uncommon. However, conventional site blocking poisoning with sulphur compounds, and particularly by H 2 S, is common. The initial phase involves interaction with surface hydroxyl groups and elimination of water. Sulphur is retained strongly on the catalyst, and when partially sulphided they can exhibit selectivity in hydrogenation of organic hydrogenations. A variety of other sulphur compounds, and some chlorinated organic compounds, can cause complete deactivation or enhanced selectivity.

357 citations


Journal ArticleDOI
TL;DR: In this article, the impact of water vapor on the formation of Co-support compounds and the resulting characteristics of Co/γ-Al 2 O 3 and Co-Ru/γ -Al 2O 3 catalysts were investigated to develop a better understanding of the nature of the cobalt compounds formed and the effect of noble metal promotion on their formation.

340 citations



Journal ArticleDOI
TL;DR: In this paper, the preparation and catalytic applications of dispersed metal catalysts supported on organic functional polymers are presented and evaluated, including multifunctional catalysis, e.g. redox-acid.
Abstract: The preparation and catalytic applications of dispersed metal catalysts supported on organic functional polymers are presented. The advantages of these catalysts, such as the easy tailoring with respect to the nature of the used support, the “nanoscale” size control of metal crystallites by the polymer framework, the high accessibility and consequent catalytic activity in a proper liquid or liquid–vapor reaction systems are stressed. Various proposed catalytic processes making use of these materials are presented and evaluated, including multifunctional catalysis, e.g. redox-acid. Interesting peculiar aspects such as the enhancement of the hydrogenation rate by nitrogen containing moieties anchored to the polymer backbone are emphasised. When suitable, a comparison with catalysts based on inorganic supports is given.

278 citations


Journal ArticleDOI
01 Feb 2001-Carbon
TL;DR: In this paper, two commercial activated carbons were used as catalyst supports in Pt/AC catalysts and the types and abundance of the oxygen bearing surface groups on each of the activated carbon supports were determined from the deconvolution of the TPD profiles of the activations.

254 citations


Journal ArticleDOI
TL;DR: In this paper, the authors studied the catalytic performance of Ni catalysts supported on different supports for the decomposition of methane into carbon and hydrogen over different supports and showed that the performance of the supported-Ni catalysts depended significantly on the pore structures of the supports.
Abstract: Decomposition of methane into carbon and hydrogen over Ni catalysts supported on different supports was studied. The catalytic activities and the lifetimes of the catalysts for the reaction were examined and are discussed. Ni catalysts supported on SiO 2 , TiO 2 and graphite showed high activities and long lifetimes for the reaction, whereas the catalysts supported on Al 2 O 3 , MgO and SiO 2 ·MgO were inactive for the reaction. The relation between the catalytic performance of the supported-Ni catalysts and the structure or electronic state of Ni species is discussed on the bases of the results of X-ray diffraction (XRD) and Ni K-edge XANES/EXAFS. In the supported-Ni catalysts effective for the methane decomposition, Ni species were present as crystallized Ni metal particles. On the other hand, the Ni species on the inactive catalysts were present as nickel oxides mainly, suggesting the formation of a compound oxide between Ni and the supports. The catalytic performance of the Ni catalysts supported on silicas with different specific surface areas and pore structures indicated that the catalytic activity and lifetime for the methane decomposition depended significantly on the pore structures of the supports. The silica support with no pore structure was the most favorable one for enhancing the catalytic activity and lifetime of the supported-Ni catalysts.

252 citations


Journal ArticleDOI
TL;DR: In this paper, the synthesis and properties of smectites and related metal oxide pillared clay (PILC) are discussed and the relation between the performance of the PILC and its physico-chemical features is addressed.
Abstract: Metal oxide pillared clay (PILC) possesses several interesting properties, such as large surface area, high pore volume and tunable pore size (from micropore to mesopore), high thermal stability, strong surface acidity and catalytic active substrates/metal oxide pillars. These unique characteristics make PILC an attractive material in catalytic reactions. It can be made either as catalyst support or directly used as catalyst. This paper is a continuous work from Kloprogge's review (J.T. Kloprogge, J. Porous Mater. 5, 5 1998) on the synthesis and properties of smectites and related PILCs and will focus on the diverse applications of clay pillared with different types of metal oxides in the heterogeneous catalysis area and adsorption area. The relation between the performance of the PILC and its physico-chemical features will be addressed.

228 citations


Journal ArticleDOI
01 Dec 2001-Cattech
TL;DR: In this paper, progress in developing a new class of support materials based on silicon carbide (SiC) is reviewed, which can be modified for specific catalytic applications through the addition of metals.
Abstract: Progress in developing a new class of support materials based on silicon carbide (SiC)is reviewed. Silicon carbide has superior mechanical and thermal properties which, coupled to chemical inertness,avoids several of the problems inherent in the use of commercial oxide and carbon based supports and catalysts. High surface area SiC can now be prepared easily in a commercially viable shape,with good mechanical properties,and at reasonable cost.I t can be shaped directly into monolith or honeycomb forms including some catalytically active material, rendering fabrication simple and cost effective. Furthermore, it can be modified for specific catalytic applications through the addition of metals. In many respects, it combines the best properties of oxide and carbon based supports without suffering many of their disadvantages.

Journal ArticleDOI
TL;DR: In this article, gallium-promoted copper-based catalysts prepared by impregnation methods on silica and ZnO supports, were examined for the hydrogenation of CO 2 to methanol.
Abstract: In this study, gallium-promoted copper-based catalysts prepared by impregnation methods on silica and ZnO supports, were examined for the hydrogenation of CO 2 to methanol. The surface characteristics of catalysts depended on the support and were related to their catalytic performance. Silica-supported catalysts tested at reaction temperatures between 523 and 543 K were highly selective and stable. The selectivity to methanol was around 99%, the conversion to CO was very low and negligible amounts of hydrocarbons were formed. The use of hydrophobic silica enhanced the performance of the catalyst in terms of activity, selectivity and stability. The modification of properties of copper particles is related to the presence of very small particles of Ga 2 O 3 on the surface.

Journal ArticleDOI
Bo-Qing Xu1, Jun-Mei Wei1, Hai-Yan Wang1, Ke-Qiang Sun1, Qiming Zhu1 
TL;DR: In this paper, a novel preparation method for MgO nanocrystals was reported, which makes use of a conventional hydrogel of Mg(OH) 2 derived from inorganic magnesium chloride.

Journal ArticleDOI
TL;DR: In this paper, the ceria-zirconia mixed oxide was used as an active catalyst for methane combustion, in the 673-1073 K temperature range, which is associated with an oxidized state of the catalysts, whereas a reduction at 573 K strongly activates the solids.

Journal ArticleDOI
TL;DR: In this article, the authors studied the catalytic properties of Pd supported on Al2O3, SiO2, TiO2 and ZrO2 for hydrogenation of carbon monoxide.
Abstract: Catalytic hydrogenation of carbon monoxide was studied over Pd supported on Al2O3, SiO2, TiO2, and ZrO2. Both the activity and the selectivity of the catalysts were strongly affected by the nature of the support. As a major product, Pd/Al2O3 produces dimethyl ether, Pd/SiO2 favors methanol formation, Pd/TiO2 produces CH4, and Pd/ZrO2 yields methanol. Higher CO conversions over Pd/ZrO2 and Pd/TiO2 were ascribed to the presence of cationic palladium species formed through the metal–support interaction. Significant dimethyl ether formation over Pd/Al2O3 was attributed to the acidity of the support metal oxide. The catalytic natures of Pd catalysts were discussed based on the results of catalyst characterization by XPS, TEM, and temperature-programmed reduction and desorption.

Journal ArticleDOI
01 Dec 2001-Carbon
TL;DR: In this paper, the relative contributions of the catalyst electronic structure and support chemical composition are evaluated with Cu, Fe and Ni as catalysts and Al2O3, CaO, SiO2 and TiO2 as support media.

Journal ArticleDOI
TL;DR: In this paper, the Ni−Au nanoparticle catalyst system is designed based on the detailed experimental and theoretical understanding of the alloying and the chemical reaction processes on single-crystal surfaces.
Abstract: We discuss the design of a Ni−Au nanoparticle catalyst system, which is based on the detailed experimental and theoretical understanding of the alloying and the chemical reaction processes on single-crystal surfaces. The alloy formation and structure of Ni−Au catalysts supported on SiO2 and on MgAl2O4 are simulated by Monte Carlo schemes as well as experimentally studied by a combination of in situ X-ray absorption fine structure, transmission electron microscopy, and in situ X-ray powder diffraction. On-line mass spectrometry is used to follow the reactivity of the catalyst and thermogravimetric analysis provided information on the deposition rate of carbon during steam reforming of n-butane. The simulations and the experiments give evidence for the formation of a Ni−Au surface alloy on the Ni particles for both supports. The Ni−Au catalysts exhibiting the surface alloy are active for steam reforming and are more resistant toward carbon formation than the pure Ni catalyst. Blocking of highly reactive Ni ...

Patent
21 Dec 2001
TL;DR: In this paper, a method for producing single-wall carbon nanotube (SWNT) catalyst supports and compositions thereof is described, and a transition metal catalyst is added to the SWNT.
Abstract: This invention relates generally to a method for producing single-wall carbon nanotube (SWNT) catalyst supports and compositions thereof. In one embodiment, SWNTs or SWNT structures can be employed as the support material. A transition metal catalyst is added to the SWNT. In a preferred embodiment, the catalyst metal cluster is deposited on the open nanotube end by a docking process that insures optimum location for the subsequent growth reaction. The metal atoms may be subjected to reductive conditions.

Journal ArticleDOI
TL;DR: In this article, a Pd/carbon nanofiber catalyst was used in the selective hydrogenation of the C C C bond in cinnamaldehyde at a reaction temperature of around 80°C, under continuous hydrogen flowing at atmospheric pressure.
Abstract: Carbon nanofibers (CNFs) prepared by decomposition of ethane over a Ni/alumina catalyst, are used as support for palladium clusters. The carbon support displays a mean diameter of 40–50 nm, lengths up to several tens of micrometers, as highlighted by transmission electron microscopy (TEM) observations and a specific surface area of about 50 m2/g. The spheroidal palladium particles have a relatively homogeneous and sharp size distribution, centered at around 4 nm. This novel Pd/carbon nanofiber catalyst displays unusual catalytic properties and is successfully used in the selective hydrogenation of the C C bond in cinnamaldehyde at a reaction temperature of around 80°C, under continuous hydrogen flowing at atmospheric pressure. The high performances of this novel catalyst in terms of efficiency and selectivity are, respectively, related to the inhibition of the mass-transfer processes over this non-porous material and to peculiar palladium–carbon interactions. It is concluded that the absence of microporosity in the carbon nanofibers favours both the high activity and selectivity which is confirmed by comparison with the commercially available high surface area charcoal supported palladium catalyst.

Journal ArticleDOI
TL;DR: In this paper, the kinetics of CO2 reforming of methane was studied over Pt supported on Al2O3, ZrO2, and x% Zr O2/Al2O 3 (1≤x≤20 wt), and the catalysts were characterized using different techniques.

Journal ArticleDOI
TL;DR: In this paper, the authors showed that the higher the calcination temperature, the higher activity of the catalyst for DMC formation, though the BET surface area is lower on the catalyst calcined at higher temperature.
Abstract: CeO2–ZrO2 solid solution catalysts are very effective for the selective synthesis of dimethyl carbonate from methanol and CO2. The activity was much dependent on the calcination temperature. The higher the calcination temperature, the higher the activity of the catalyst for DMC formation, though the BET surface area is lower on the catalyst calcined at higher temperature.

Journal ArticleDOI
TL;DR: The Heck reaction finds several applications in industry because it is one of the effective tools for the formation of a new C-C bond as mentioned in this paper. In addition to the catalytic activity and selectivity, catalyst-product separation strategies are very important for the industrial application.
Abstract: The Heck reaction finds several applications in industry because it is one of the effective tools for the formation of a new C─C bond. In addition to the catalytic activity and selectivity, catalyst–product separation strategies are very important for the industrial application. There are various methods of interest ranging from conventional heterogeneous catalysts to heterogenization of homogeneous catalysts. The heterogeneous catalysts are classified into supported metal catalysts, zeolite-encapsulated catalysts, colloids–nanoparticles, and intercalated metal compounds. The homogeneous metal complexes catalysts are heterogenized using modified silica catalysts, polymer-supported catalysts, biphasic catalysts, supported liquid-phase catalysts, nonionic liquids solvents, perfluorinated solvents, and reusable homogeneous complexes. In general, heterogeneous catalysts are effective and stable at higher temperatures, which may be important for the activation of less reactive but less expensive chloroaryls su...

Journal ArticleDOI
TL;DR: In this paper, the role of CO2 in the dehydrogenation of ethane over Ga2O3-loaded catalysts was examined, and it was found that CO2 markedly promoted the degradation of the product (ethene) from the catalyst surface.

Journal ArticleDOI
TL;DR: In this paper, the effects of nickel loading, calcination temperature, support, and basic additives on Ni-based catalyst structure and reactivity for CH4 reforming with CO2 were investigated.
Abstract: The effects of nickel loading, calcination temperature, support, and basic additives on Ni-based catalyst structure and reactivity for CH4 reforming with CO2 were investigated. The results show that the structure of the nickel active phase strongly depends on the interactions of the metal and the support, which are related to the support properties, the additives and the preparation conditions. “Free” Ni species can be formed when the interaction is weak and their mobility makes them easily deactivated by coking and sintering. The effect of strong metal-support interaction (SMSI effect) is different for various supports. The formation of solid solution of Ni–Mg–O2 and the blocking of TiOx by the partially reduced TiO2 can both decrease the availability of Ni active sites in Ni/MgO and Ni/TiO2. The spinel NiAl2O4 formed in Ni/γ-Al2O3 might be responsible for its high activity and resistance to coking and sintering because it can produce a highly dispersed active phase and a large active surface area as bound-state Ni species when the catalyst is prepared at high calcined temperatures or with low nickel loading. The addition of La2O3 or MgO as alumina modifiers can also be beneficial for the performance of the Ni/γ-Al2O3 catalyst.

Journal ArticleDOI
03 Sep 2001
TL;DR: In this article, the performance of ruthenium-tin catalysts for the liquid phase selective hydrogenation of oleic acid to unsaturated alcohols has been investigated.
Abstract: The performance of ruthenium-tin catalysts for the liquid phase selective hydrogenation of oleic acid to unsaturated alcohols has been investigated. Titania-supported ruthenium and ruthenium-tin catalysts prepared by conventional impregnation as well as alumina-supported sol–gel ruthenium and ruthenium-tin catalysts have been used. The hydrogenation over the monometallic ruthenium catalysts leads primarily to the saturated stearic acid, which is then consecutively hydrogenated to the saturated stearyl alcohol. The titania-supported monometallic ruthenium catalyst shows a greater activity than the alumina-supported sol–gel one for the hydrogenation of oleic acid to the saturated stearyl alcohol. The hydrogenation over the bimetallic ruthenium-tin catalysts is characterized by the near total suppression of the hydrogenation of the olefine bond in favor of the activation of the hydrogenation of the carboxylic bond, thus leading to the selective formation of unsaturated alcohols. Besides, these catalysts are active for the cis–trans isomerization reaction of the oleic acid to elaidic acid, in competition with the hydrogenation of the carboxylic group. The impregnated titania-supported ruthenium-tin catalyst shows a better performance than the alumina-supported sol–gel ruthenium-tin catalyst for the selective hydrogenation of oleic acid to unsaturated alcohols.

Journal ArticleDOI
Xiaoyin Chen1, Yong Liu1, Guoxing Niu1, Zhuxian Yang1, Maiying Bian1, Adi He1 
TL;DR: In this paper, the effects of precursor pretreatment and addition methods of lanthanum species on stabilization of alumina have been investigated by BET specific surface area measurements (BET), X-ray powder diffraction (XRD), N2 adsorption-desorption isotherms, thermal analysis, and Xray photoelectron spectroscopy (XPS) in the range of 600-1150°C.
Abstract: The effects of precursor pretreatment and addition methods of lanthanum species on stabilization of alumina (surface area loss, phase transformations and high temperature interaction with lanthanum species) have been investigated by BET specific surface area measurements (BET), X-ray powder diffraction (XRD), N2 adsorption–desorption isotherms, thermal analysis and X-ray photoelectron spectroscopy (XPS) in the range of 600–1150°C. Although powder La2O3, which is mechanically mixed with γ-Al2O3 or pseudo boehmite, can effectively retard the α phase transformation by solid phase interaction with Al2O3, it does not show a positive effect on retarding the loss of surface area. Compared with the direct impregnation of γ-Al2O3, the gelation of pseudo boehmite by acidification accelerates phase transformations and weakens the stabilizing influence of lanthanum species. At 600°C and for atomic ratio of La/Al up to 0.1 or at 1150°C and La/Al≤0.02, the lanthanum species is highly dispersed in alumina. With the increase of calcination temperature or lanthanum content, lanthanum species is present as dispersed La2O3, LaAlO3 and crystalline La2O3. At T≤1000°C the surface area loss of alumina is mainly attributed to the sintering of particles. The follow-up loss at T>1000°C results from both sintering and phase transformations. The highly dispersed lanthanum species retard both sintering and phase transformations, and their associated surface area loss. However, the formation of LaAlO3 mainly retards the surface area loss resulting from the α phase transformation. Having considered the purely mechanical mixing effect of additive on the surface area loss of alumina, an influence criterion of lanthanum species on retarding the surface area loss whether resulting from sintering or from α phase transformation at high temperature ≥1000°C has been proposed in this paper.

Journal ArticleDOI
TL;DR: In this article, the SAXS measurements show that the hexagonal mesoscopic organization of SBA-15 support with pore diameter of 5.5-6.5 nm is almost retained even after addition of 20-mass% Co.

Journal ArticleDOI
TL;DR: The catalytic activity and selectivity of palladium supported on various metal oxides and zeolites in carbon-carbon coupling reactions of aryl bromides with olefins (Heck reaction) are reported and reviewed in this article.

Journal ArticleDOI
TL;DR: In this paper, the authors survey the literature on mesoporous oxides as a support for base metal oxides and then focus on three systems studied more closely in their research group.

Journal ArticleDOI
TL;DR: In this paper, a Pd-Pt/TS-1 catalyst with in situ formed hydrogen peroxide was used for propylene epoxidation in a fixed bed reactor under high pressure conditions.
Abstract: Propylene epoxidation over a Pd–Pt/TS-1 catalyst with in situ formed hydrogen peroxide was carried out in a fixed bed reactor under high pressure conditions. The continuous operation allowed the study of catalyst deactivation and changes in product distribution with time-on-stream. The initial propylene oxide selectivity was very high, 99% at 3.5% conversion, but the catalyst deactivated rapidly with time-on-stream and successively the formation of methyl formate became the prevalent reaction. Using carbon dioxide, instead of nitrogen, had a beneficial effect on the formation of propylene oxide, and even higher yields were obtained when increasing the pressure from 50 to 120 bar (supercritical fluid phase). Thermal analysis (TA-MS and TA-FTIR) indicated that catalyst regeneration requires oxidation at elevated temperature; washing with an organic solvent is less efficient. The serious catalyst deactivation and the striking shift in the selectivity pattern of the catalyst is traced to competing alcohol oxidation on platinum metal.