Showing papers on "Catalyst support published in 1994"

Catalytic Air Pollution Control: Commercial Technology

Abstract: Preface. ACKNOWLEDGEMENTS. ACKNOWLEDGEMENTS, FIRST EDITION. ACKNOWLEDGEMENTS, SECOND EDITION. I. FUNDAMENTALS. 1. Catalyst Fundamentals. 1.1 Introduction. 1.2 Catalyzed Verses Non-Catalyzed Reactions. 1.3 Catalytic Components. 1.4 Selectivity. 1.5 Promoters and their Effect on Activity and Selectivity. 1.6 Dispersed Model for Catalytic Component on Carrier: Pt on Al 2 O 3 . 1.7 Chemical and Physical Steps in Heterogeneous Catalysis. 1.8 Practical Significance of knowing the Rate-Limiting Step. 2. The Preparation of Catalytic Materials: Carriers, Active Components, and Monolithic Substrates. 2.1 Introduction. 2.2 Carriers. 2.3 Making the Finished Catalyst. 2.4 Nomenclature for Dispersed Catalysts. 2.5 Monolithic Materials as Catalyst Substrates. 2.6 Preparing Monolithic Catalysts. 2.7 Catalytic Monoliths. 2.8 Catalyzed Monoliths Nomenclature. 2.9 Precious Metal Recovery from Monolithic Catalysts. 3. Catalyst Characterization. 3.1 Introduction. 3.2 Physical Properties of Catalysts. 3.3 Chemical and Physical Morphology Structures of Catalytic Materials . 3.4 Techniques for Fundamental Studies. 4. Monolithic Reactors for Environmental Catalysis. 4.1 Introduction. 4.2 Chemical Kinetic Control. 4.3 The Arrhenius Equation and Reaction Parameters. 4.4 Bulk Mass Transfer. 4.5 Reactor Bed Pressure Drop. 4.6 Summary. 5. Catalyst Deactivation. 5.1 Introduction. 5.2 Thermally Induced Deactivation. 5.3 Poisoning. 5.4 Washcoat Loss. 5.5 General Comments on Deactivation Diagnostics in Monolithic Catalysts for Environmental Applications. II. MOBILE SOURCE. 6. Automotive Catalyst. 6.1 Emissions and Regulations. 6.2 The Catalytic Reactions for Pollution Abatement. 6.3 The Physical Structure of the Catalytic Converter. 6.4 First-Generation Converters: Oxidation Catalyst (1976-1979). 6.5 NOx, CO and HC Reduction: The Second Generation: The Three Way Catalyst (1979 - 1986). 6.6 Vehicle Test Procedures (U.S., European and Japanese). 6.7 NOx, CO and HC Reduction: The Third Generation (1986 - 1992). 6.8 Palladium TWC Catalyst: The Fourth Generation (Mid-1990s). 6.9 Low Emission Catalyst Technologies. 6.10 Modern TWC Technologies for the 2000s. 6.11 Towards a Zero-Emission Stoichiometric Spark-Ignit Vehicle. 6.12 Engineered Catalyst Design. 6.13 Lean-Burn Spark-Ignited Gasoline Engines. 7. Automotive Substrates. 7.1 Introduction to Ceramic Substrates. 7.2 Requirements for Substrates. 7.3 Design Sizing of Substrates. 7.4 Physical Properties of Substrates. 7.5 Physical Durability. 7.6 Advances in Substrates. 7.7 Commercial Applications. 7.8 Summary. 8. Diesel Engine Emissions. 8.1 Introduction. 8.2 Worldwide Diesel Emission Standards. 8.3 NO x -Particulate Tradeoff. 8.4 Analytical Procedures for Particulates. 8.5 Particulate Removal. 8.6 NOX Reduction Technologies. 8.7 2007 Commercial System Designs (PM Removal Only). 8.8 2010 Commercial System Approaches under Development (PM and NO x Removal). 8.9 Retrofit and Off-Highway. 8.10 Natural Gas Engines. 9. Diesel Catalyst Supports and Particulate Filters. 9.1 Introduction. 9.2 Health Effects of Diesel Particulate Emissions. 9.3 Diesel Oxidation Catalyst Supports. 9.4 Design/Sizing of Diesel Particulate Filter. 9.5 Regeneration Techniques. 9.6 Physical Properties and Durability. 9.7 Advances in Diesel Filters. 9.8 Applications. 9.9 Summary. 10. Ozone Abatement within Jet Aircraft. 10.1 Introduction. 10.2 Ozone Abatement. 10.3 Deactivation. 10.4 Analysis of In-Flight Samples. 10.5 New Technology. III. STATIONARY SOURCES. 11. Volatile Organic Compounds . 11.1 Introduction. 11.2 Catalytic Incineration. 11.3 Halogenated Hydrocarbons. 11.4 Food Processing. 11.5 Wood Stoves. 11.6 Process Design. 11.7 Deactivation. 11.8 Regeneration of Deactivated Catalysts. 12. Reduction of NO x . 12.1 Introduction. 12.2 Nonselective Catalytic Reduction of NOx. 12.3 Selective Catalytic Reduction of NOx. 12.4 Commercial Experience. 12.5 Nitrous Oxide (N 2 O). 12.6 Catalytically Supported Thermal Combustion. 13. Carbon Monoxide and Hydrocarbon Abatement from Gas Turbines. 13.1 Introduction. 13.2 Catalyst for CO Abatement. 13.3 Non-Methane Hydrocarbon (NMHC) Removal. 13.4 Oxidation of Reactive Hydrocarbons. 13.5 Oxidation of Unreactive Light Paraffins. 13.6 Catalyst Deactivation. 14. Small Engines. 14.1 Introduction. 14.2 Emissions. 14.3 EPA Regulations. 14.4 Catalyst for Handheld and Nonhandheld Engines. 14.5 Catalyst Durability. IV. NEW AND EMERGING TECHNOLOGIES. 15. Ambient Air Cleanup. 15.1 Introduction. 15.2 Premair (R) Catalyst Systems. 15.3 Other Approaches. 16. Fuel Cells and Hydrogen Generation. 16.1 Introduction. 16.2 Low-Temperature PEM Fuel Cell Technology. 16.3 The Ideal Hydrogen Economy. 16.4 Conventional Hydrogen Generation. 16.5 Hydrogen Generation from Natural Gas for PEM Fuel Cells. 16.6 Other Fuel Cell Systems. INDEX.

Conversion of methane and carbon dioxide into synthesis gas over alumina-supported nickel catalysts. Effect of Ni-Al2O3 interactions

Abstract: A series of alumina-supported nickel catalysts were prepared by calcination of the catalyst precursors in air at different temperatures. The increase in the intensity of Ni-Al2O3 interactions with the calcination temperature was found to be unfavourable to the reduction of the catalyst, and thus caused a decrease in activity for the low temperature reaction between methane and carbon dioxide. However, the catalyst with strong Ni-Al2O3 interactions suppressed carbon deposition effectively, which can be attributed to the formation of spinel, NiAl2O4, after calcination. When the reaction was carried out at 1023 K, all the catalysts tended to exhibit the same activity. At the same time, only filamentous carbon with a hollow inner channel was observed and there were nickel particles on the tip of this filamentous carbon.

Design and synthesis of a heterogeneous asymmetric catalyst

Abstract: The need for enantiomerically pure pharmaceuticals and insecticides drives the search for new catalysts that can perform asymmetric reactions with high enantiomeric selectivity. Many chiral transformations are accomplished using homogeneous catalysts. Recently we reported a heterogeneous catalyst for asymmetric hydrogenation reactions, in which an organometallic catalytic complex is held in a film of water on a porous hydrophilic support, while the reactants and products remain within a hydrophobic organic phase. Such systems provide a large interfacial area between the catalytic phase and the solvent, and should facilitate the separation of product from catalyst. Our previous system gave selectivities of only about 70% enantiomeric excess, however, whereas values of at least 95% are needed for practical utility. Here we describe a modified process in which an enantiomeric excess of 96% is obtained for the asymmetric reduction of 2-(6′-methoxy-2′-naphthyl)acrylic acid to the commercially important anti-inflammatory agent naproxen. We use ethylene glycol as the hydrophilic liquid phase containing the chiral catalyst, which effectively prevents the leaching of the complex into the organic phase. Our results show that these supported-phase asymmetric catalytic systems have the potential to become commercially viable.

Zeolite-containing oxidation catalyst and method of use

Abstract: Oxidation catalyst compositions for treating diesel exhaust include ceria and, optionally, alumina, each having a surface area of at least about 10 m 2 /g, and a zeolite, e.g., Beta zeolite. Optionally, platinum may be included in the catalytic material, preferably in amounts which are sufficient to promote some gas-phase oxidation of carbon monoxide (“CO”) and hydrocarbons (“HC”) but which are limited to preclude excessive oxidation of SO 2 to SO 3 . Alternatively, palladium in any desired amount may be included in the catalytic material. The zeolite is optionally doped, e.g., ion-exchanged, with one or more of hydrogen, a platinum group metal or other catalytic metals. The catalyst compositions may be used in a method to treat diesel engine exhaust by contacting the hot exhaust with the catalyst composition to promote the oxidation of gas-phase CO and HC and of the volatile organic fraction component of particulates in the exhaust.

Polymerization catalysts, their production and use

Abstract: The invention generally relates to a catalyst, particularly a metallocene catalyst and catalyst system useful in the polymerization of olefins into a polymer product. The polymer product has a broad molecular weight distribution, a high molecular weight and a narrow composition distribution and is easily processable.

Multicomponent Bismuth Molybdate Catalyst: A Highly Functionalized Catalyst System for the Selective Oxidation of Olefin

Abstract: Publisher Summary This chapter focuses on the multicomponent bismuth molybdate catalyst which is a highly functionalized catalyst system for the selective oxidation of olefin. Some progress is made in explaining the splendid catalytic performance of multicomponent bismuth molybdates that are used widely for the industrial oxidations and ammoxidations of lower olefin. The catalytic activity and selectivity are enhanced by the multifunctionalization of the catalyst systems. Many functions newly introduced are deeply associated with lattice vacancies formed by the introductions of third and fourth elements. The design of the excellent oxidation catalyst depends seriously on the method of selecting these additives by considering their valencies, electronegativities, and ionic radii. The rapid migration of oxide ion and electron transfer are also important in enhancing the catalyst stability. Thus, the appropriate introduction of additional elements into the catalyst system makes it more flexible and durable under the working conditions.

Die großtechnische Oxosynthese mit immobilisiertem Katalysator

Abstract: Industrial Oxo Synthesis with Immobilised Catalyst. The use of water-soluble catalysts represents a significant advance in homogeneous catalysis; “immobilisation” of the catalyst in a second immiscible liquid phase has the effect of “heterogenisation” and allows the advantages of heterogeneous processing (long lifetimes, straightforward technology) to the combined with those of the homogeneous mode (gentle reaction conditions, high activity and selectivity). In particular, the decisive advantage of homogeneous catalysts, viz. the wide range of variation of their steric and electronic properties which can be adapted to the specific reaction at hand, can be exploited for tailoring highly effective catalysts. Moreover, the mode of action of these homogeneous catalysts remains understandable as a model and under the reaction conditions chosen – in complete contrast to the case of many heterogeneous catalytic systems. The first successful industrial application of water-soluble catalysts was in the oxo process of Ruhrchemie/Rhǒne Poulenc. The following article reports on ten years' experience with this process and the HRh(CO)[P(msulphophenyl-Na)3]3 catalyst.

Influence of the preparation method and the nature of the support on the stability of nickel catalysts

Abstract: The influence of the preparation method and the nature of the support on the stability of the metal dispersion in nickel catalysts was studied Three different preparation methods, incipient wetness, ion exchange and precipitation-deposition using three different commercial supports, silica, alumina and silica-alumina were used The metallic dispersion stability was evaluated by hydrogen adsorption measurements after high-temperature calcination of the samples before and after reduction Results have shown that the behaviour of the samples depends on the balance between positive and negative effects in the metal-support interaction, ie, the increase of the initial metal dispersion and its resistance against sintering and, the loss of nickel in the form of difficult to reduce interaction compounds Interaction depends on the preparation method, but can be considerably modified during catalyst life The reactivity of the support towards nickel plays an important role in these changes The catalyst prepared by precipitation-deposition over silica showed the best metallic dispersion and stability

Zirconium/cerium mixed oxide catalyst/catalyst support compositions having high/stable specific surfaces

Abstract: Zirconium/cerium mixed oxides (optionally including thermally stabilizing dopant values), comprising solid solutions thereof, having contents of zirconium of up to 99% by weight, and having high specific surface areas, are well suited as catalysts and/or catalyst supports, notably for the treatment/conversion of vehicular exhaust gases; such ZrO 2 /CeO 2 mixed oxides are conveniently prepared by (i) intimately admixing a zirconium sol with a cerium sol, the ratio r of the mean diameter r 1 of the particles of the zirconium sol to the diameter r 2 of the particles of the cerium sol being at least 5, (ii) adding a precipitating amount of a base thereto, (iii) recovering the precipitate thus formed, and (iv) calcining the recovered precipitate.

Reduction of sulfur dioxide by carbon monoxide to elemental sulfur over composite oxide catalysts

Abstract: The catalyst activity of fluorite-type oxide, such as ceria and zirconia, for the reduction of sulfur dioxide by carbon monoxide to elemental sulfur can be significantly promoted by active transition metals, such as copper. More than 95% elemental sulfur yield, corresponding to almost complete sulfur dioxide conversion, was obtained over a Cu-Ce-O oxide catalyst with a feed gas of stoichiometric composition ([CO]/[SO 2 ]=2) at temperatures above 450°C. This type of mixed metal oxide catalyst has stable activity and is resistant to water and carbon dioxide poisoning. XPS analysis found copper in the Cu-Ce-O oxide in a reduced oxidation state (Cu 1+ , Cu 0 ). The stable fluorite-type structure, regarded as the backbone structure of the catalyst, existed in both the fresh and the spent catalyst. The high activity resulted from the strong interaction of transition metal and fluorite oxide.

Catalyst supports, supported catalysts and methods of making and using the same

Abstract: A supported catalyst comprising a carbon fibril aggregate and a catalytically effective amount of a catalyst supported therein, a process for performing a catalytic reaction in fluid phase using the supported catalyst and a process for making the supported catalyst are disclosed.

Catalyst for direct reduction of carboxylic acid, process for preparation thereof and process for preparation of alcohol compound using the catalyst

Abstract: Disclosed are a catalyst for directly reducing a carboxylic acid, the catalyst comprising a tin compound and a ruthenium compound supported on a carrier, the catalyst being prepared by the steps of calcining the tin compound in the presence of oxygen after deposition of the tin compound alone on the carrier, and activating the obtained product after deposition of the ruthenium compound on said carrier, a process for preparing the catalyst, and a process for preparing an alcohol compound using the catalyst.

The selective hydrogenation of acetonitrile on supported nickel catalysts

Abstract: The catalytic behavior of several supported nickel catalysts in the hydrogenation of acetonitrile was studied. It was established that the selectivity of this process is greatly influenced by the nature of the support used. Catalysts consisting of nickel supported on acidic supports catalyzed the formation of condensation products, diethyl- and triethylamine. Nickel supported on basic supports was highly selective with respect to the formation of the primary amine, ethylamine. It was shown that modification of the intrinsic acidity of alumina-based supports by the application of alkaline additives has a large impact on the selectivity of the resulting catalyst. Based on the results obtained from measurements on a basic catalyst diluted with either an acidic or a basic support, a dual-function mechanism is suggested. The mechanism implies that the hydrogenation function of the catalyst is located on the metal, while the acid function, responsible for the condensation reactions, is located on the support. A mechanism, accounting for the occurrence of the acid-catalyzed condensation reactions, is proposed.

Oxidation catalyst with bulk ceria, a second bulk metal oxide, and platinum

Abstract: Oxidation catalyst compositions include a catalytic material having a BET surface area of at least about 10 m 2 /g and consisting essentially of a combination of bulk ceria and a bulk second metal oxide which may be one or more of titania, zirconia, ceria-zirconia, silica, alumina-silica and α-alumina The combination may optionally also include activated alumina having a BET surface area of at least about 10 m 2 /g The ceria, second metal oxide and optional activated alumina may be mixed together or provided as discrete layers Optionally, one of platinum or palladium metal may be dispersed on the catalytic material provided that the platinum, when used, is used in limited amounts to preclude excessive oxidation of SO 2 to SO 3 The catalyst compositions may be used for oxidation of oxidizeable components in a gas-borne stream, eg, in a method to treat diesel engine exhaust by contacting the hot exhaust with the catalyst composition to promote the oxidation of the volatile organic fraction The optional inclusion of platinum or palladium promotes the oxidation of gas phase components, eg, hydrocarbons and carbon monoxide

Kinetics and mechanism of catalytic oxidation of formaldehyde over hydrophobic catalysts

Abstract: Catalytic oxidation is an attractive way to reduce volatile organic compound (VOC) emissions to meet the requirements of air pollution control regulations. The kinetics and mechanism are reported for the oxidation of formaldehyde with air over a hydrophobic catalyst. The measured catalyst activity and selectivity varied with temperature. A mathematical model, based on the Mars-van Krevelen mechanism, has been developed which describes the determined catalyst selectivity and reaction rate. The advantage of using a hydrophobic catalyst over a conventional hydrophobic catalyst is demonstrated by the kinetic parameters. The model can also be used for the quantitative prediction of formaldehyde oxidation at various operating conditions.

Support for catalysts, process for the manufacture of a precursor gel of a support for catalysts, catalyst for the polymerization of olefins and process for the polymerization of olefins by means of this catalyst

Abstract: Support for catalysts, containing at least two constituents chosen from silica, alumina and aluminium phosphate, having a specific surface of 100 to 800 m 2 /g, a crystallization temperature greater than or equal to 700° C. and a pore volume of 1.5 to 4 cm 3 /g, the specific surface (SS) and the pore volume (PV) corresponding to the relationship: SS<(PV×564-358). Process for the manufacture of such a support, according to which an alcohol, water, a silicon alkoxide and an acid are mixed under conditions such that gelling or precipitation of silica is prevented, an acidic solution of an aluminium compound and/or a solution of a source of phosphate ions are added thereto, a gelling agent is added thereto, a gel is recovered which is washed with water and then by means of an organic liquid, the gel is then dried until a powder is obtained, and the powder is calcined. Polymerization of olefins in the presence of a catalyst containing chromium on a support as described above.

Intermediate hydrocarbon species for the CO2-CH4 reaction on supported Ni catalysts

Abstract: By using pulse surface reaction rate analysis (PSRA), the detailed structure of the intermediate hydrocarbon species was revealed by measuring the dynamic behavior of both CO and H2 produced from the CO2-CH4 reaction on supported Ni catalysts. It was found that the number of hydrogen atoms involved in the intermediate was different from one catalyst support to another: 2.7 for MgO, 2.5 for ZnO, 2.4 for Al2O3,1.9 for TiO2, and 1.0 for SiO2.

Method for making a catalyst system

Abstract: This invention is generally directed toward a catalyst system useful for polymerizing olefins. The method for preparing the catalyst of the invention provides for combining a bulky ligand transition metal catalyst with an activator that has been aged, optionally with a support. The catalyst system is useful in any polymerization process.

Carbon Dioxide Reforming of Methane on Supported Nickel Catalysts

Abstract: The reforming of CH4 with CO2 using various Ni catalysts has been investigated. As a result of screening tests, the selection of supports was found to be very important to control the catalytic activity of Ni. Among the various supports, ceramic foam and Al2O3 supports incorporating industrial steam reforming catalysts showed higher activities than SiO2 supports. The kinetic study has shown that the results could be expressed by a simple power-law equation for the three activated catalysts. The effect of the support was also studied. The results showed the importance of the acid-base property of the catalyst.

Oxidative decomposition of formaldehyde on silver-cerium composite oxide catalyst

Abstract: Silver-cerium composite oxide was active for low temperature oxidative decomposition of formaldehyde. Its high activity was due partly to the high dispersion of active silver on the CeO2. The surface oxygen of this composite catalyst was removed more easily than those on single component Ag2O or CeC2, which also seemed to contribute to the high activity of this catalyst. IR analysis revealed that formaldehyde was decomposed both on silver-cerium composite catalyst and CeO2 in the presence of oxygen to produce methoxide, dioxymethylene, and/or polyoxymethylene even at room temperature. In addition bi-carbonate was formed on silver-cerium composite catalyst and formate was produced on CeO2. These intermediates suffered further oxidation at higher temperatures (373 and 423 K) easily on silver-cerium composite catalyst, whereas degradation of them was rather difficult on CeO2.