Abstract: The invention relates to a process for preparing Cu/Zn/Al catalysts. In this process, the metals are used in the form of their formates and are precipitated in a suitable form. Suitable precipitants are, for example, alkali metal carbonates. The invention further relates to a catalyst as can be obtained by the process according to the invention and to its use.

Abstract: The present invention involves a process and materials for simultaneous desulfurization and water gas shift of a gaseous stream comprising contacting the gas stream with a nickel aluminate catalyst. The nickel aluminate catalyst is preferably selected from the group consisting of Ni2xAl2O2x+3, Ni(2?y)Ni0yAl2O(5?y), Ni(4?y)Ni0yAl2O(7?y), Ni(6?y)Ni0yAl2O(9?y), and intermediates thereof, wherein x?0.5 and 0.01?y?2. Preferably, x is between 1 and 3. More preferably, the nickel containing compound further comprises Ni2xAl2O2x+3?zSz wherein 0?z?2x.

Abstract: Methods for producing hydrogen via the water-gas shift reaction utilizing a palladium-zinc on alumina catalyst are described.

Abstract: The invention relates to a process for producing a hydrogen-rich stream from a hydrogen-depleted stream. More particularly, the invention relates to a hydrocarbon synthesis process, by way of example, a Fischer Tropsch process, from which both hydrocarbons and high purity hydrogen are obtained. The process comprises contacting the hydrogen-depleted stream with a reverse-selective membrane to provide a CO2-enriched permeate and a hydrogen-containing retentate. The high purity hydrogen is produced from the hydrogen-containing retentate. The high purity hydrogen thus obtained may be used in a process selected from the group consisting of upgrading hydrocarbons produced from the hydrocarbon synthesis process, hydrotreating a natural gas stream, recycling to the hydrocarbon synthesis reaction unit, high purity hydrogen production, catalyst rejuvenation, and combinations thereof.

Abstract: A method and catalysts and fuel processing apparatus for producing a hydrogen-rich gas, such as a hydrogen-rich syngas are disclosed. According to the method a CO-containing gas, such as a syngas, contacts a water gas shift catalyst in the presence of water, preferably at a temperature of less than about 450° C. to produce a hydrogen-rich gas, such as a hydrogen-rich syngas. Also disclosed is a water gas shift catalyst comprising: a) Pt, its oxides or mixtures thereof; b) at least one of Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, their oxides and mixtures thereof; and c) at least one of Sc, Y, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ir, Ni, Pd, La, Ce, Pr, Nd, Sm, Eu, their oxides and mixtures thereof. The WGS catalyst may be supported on a carrier, such as any one member or a combination of alumina, zirconia, titania, ceria, magnesia, lanthania, niobia, yttria and iron oxide. Fuel processors containing such water gas shift catalysts are also disclosed.

Abstract: A hydrogen permeable membrane, which includes a polymer stable at temperatures of about 200 C having clay impregnated with Pt or Au or Ru or Pd particles or mixtures thereof with average diameters of less than about 10 nanometers (nms) is disclosed. The membranes are useful in fuel cells or any device which requires hydrogen to be separated from carbon monoxide.

Abstract: A water gas shift catalyst comprising a platinum group metal dispersed on an inorganic oxide support modified with a carbon-containing burn-out additive and a rare earth oxide. A water gas shift catalyst containing alumina, a platinum group metal, and oxides of Pr and Nd are also disclosed.

Abstract: A method and catalysts for producing a hydrogen-rich syngas are disclosed. According to the method a CO-containing gas contacts a water gas shift (WGS) catalyst, in the presence of water, preferably at a temperature of less than about 450° C. to produce a hydrogen-rich syngas. Also disclosed is a water gas shift catalyst formulated from: a) Pt, its oxides or mixtures thereof, b) at least one of Fe and Rh, their oxides and mixtures thereof, and c) at least one member selected from the group consisting of Sc, Y, Ti, Zr, V, Nb, Ta, Mo, Re, Co, Ni, Pd, Ge, Sn, Sb, La, Ce, Pr, Nd, Sm, and Eu, their oxides and mixtures thereof. The WGS catalyst may be supported on a carrier, such as any one member or a combination of alumina, zirconia, titania, ceria, magnesia, lanthania, niobia, yttria and iron oxide. Fuel processors containing such water gas shift catalysts are also disclosed.

Abstract: A man portable hydrogen source, the source comprising one or more hydrogen generating elements, an ignition control system and a pressure vessel. Each hydrogen generating element comprises a pellet holder provided with one or more recesses and a thermal insulation layer to reduce heat transfer to adjacent hydrogen generating elements; wherein at least one recess contains a pellet of a chemical mixture which on thermal decomposition evolves hydrogen gas; wherein the ignition control system comprises one or more igniters, associated with an individual pellet, and activation means to activate the igniters; and wherein the evolved hydrogen and hydrogen generating elements are contained within the pressure vessel.

Abstract: The invention is directed toward methods of using alkali-containing catalysts for generation of hydrogen-rich gas at temperatures of less than about 260° C. A WGS catalyst of the invention may have the following composition: a) at least one of Pt, Ru, their oxides and mixtures thereof; b) Na, its oxides or mixtures thereof; and optionally, c) Li, its oxides and mixtures thereof. The catalysts may be supported on a variety of catalyst support materials. The invention is also directed toward catalysts that exhibit both high activity and selectivity to hydrogen generation and carbon monoxide oxidation.

Abstract: Applying an acid treatment to eggshells provides a sorbent with unexpectedly high CO2 capture capacity and ability to regenerate.

Abstract: The present invention discloses a method for removing carbon monoxide (CO) from a gas mixture containing CO including contacting the gas mixture with a nano-gold catalyst to reduce the CO content in the gas mixture by CO selective adsorption/oxidation, water gas shift reaction or CO selective oxidation reaction. The nano-gold catalyst includes a solid support and gold deposited on the support, wherein the deposited gold has a size less than 10 nm, and the support is a mixed metal hydroxide and oxide having the following formula: M(OH)qOy Wherein M is Ti, Fe, Co, Zr, or Ni; q is 0.1-1.5; and q+2y=z, wherein z is the valence of M.

Abstract: A method for separating a reactive gas from a feed gas mixture is disclosed. The method includes reacting the reactive gas with a bed of reactive solid in an exothermic reaction to create a second solid and a product gas from which the reactive gas is depleted. The product gas is removed and the heat from the reaction is used to liberate the reactive gas from the second solid in an endothermic reaction which yields the reactive solid. The reactive gas is removed and sequestered. Heat reservoir material is included in the bed to retain the heat in support of the endothermic reaction. A device for executing the method having an insulated chamber holding the bed, as well as process units formed of multiple beds are also disclosed. The process units allow the method to be operated cyclically, providing a continuous flow of feed gas, reactive gas and product gas.

Abstract: A process for the preparation of a hydrogen-rich stream comprising contacting a carbon monoxide-containing gas, methanol and water in at least one shift step in the presence of a catalyst comprising copper, zinc and aluminium and/or chromium at a shift inlet temperature of at least 280° C. and a pressure of at least 2.0 MPa.

Abstract: A method and apparatus for the production of hydrogen-rich gas are provided. The method and apparatus prevent over-reduction of iron oxide-based shift catalyst by introducing an oxidative stream along with a carbon monoxide containing gaseous feed stream from a catalytic steam reformer to the catalyst bed region and thereby limits structural deterioration of the catalyst. Various sources may provide the oxidative stream including a shift catalyst bed region and a selective oxidation catalyst region.

Abstract: A combination comprising a bed of a particulate copper-containing catalyst and, a guard bed of a particulate composition containing a) lead and/or at least one lead compound that reacts with hydrogen chloride and b) a support therefor. The lead compound is preferably lead nitrate. The combination is of particular utility for the low temperature shift reaction wherein carbon monoxide is reacted with steam to produce hydrogen and carbon dioxide.

Abstract: The present invention relates to a process for production of electric energy and CO2 from a hydrocarbon feedstock comprising steam reforming of the feedstock, separation and combustion of hydrogen and separation of CO2. Further the invention relates to a power plant for performing the process.

Abstract: Operating conditions for generating hydrogen by the water-gas shift reaction have been found which reduce the aging of Pt—Re bimetallic water-gas shift catalysts. The process parameters provide a stable operation in residential fuel processors and in hydrogen generators for on-site hydrogen generation.

Abstract: This invention provides a method involving the use of a non-ammonia-based deNOx catalyst for reducing the amount of NOx in exhaust combustion gas discharged from a boiler and an internal-combustion engine, wherein NOx and CO contained in exhaust gas are allowed to selectively react to reduce and remove NOx. This method involves the use of a catalyst comprising a cerium-zirconium composite oxide with Au supported thereon or a catalyst comprising a cerium-oxide-containing porous carrier with zirconium and Au supported thereon. Use of such catalyst enables purification of NOx and CO in exhaust gas and also enables generation of hydrogen.

Abstract: Microchannel devices and method of use are disclosed wherein a reaction microchamber 52 is in thermal contact with a heat exchange channel 61. An equilibrium limited exothermic chemical process occurs in the reaction microchamber 52. Sufficient heat is transferred to the heat exchange channels to substantially lower the temperature in the reaction microchamber 52 down its length to substantially increase at least one performance parameter of the exothermic chemical process relative to isothermal operation. Optionally, an endothermic reaction occurs in the heat exchange channel 61 which is sustained by the exothermic chemical process occurring the exothermic reaction chamber. Both the reaction chamber 52 and the heat exchange channel 61 can be of micro dimension. Catalyst 75 can be provided in the microchamber 52 in sheet form such that reactants flow by the catalyst sheet.

Abstract: The invention relates to methods of using noble metal-free nickel catalysts to generate a hydrogen-rich gas from gas mixtures containing carbon monoxide and water, such as water-containing syngas mixtures, where the nickel may exist in either a supported or a bulk state. The noble metal-free water gas shift catalyst of the invention comprises Ni in either a supported or a bulk state and at least one of Ge, Cd, In, Sn, Sb, Te, Pb, their oxides and mixtures thereof. The invention is also directed toward noble metal-free nickel catalysts that exhibit both high activity and selectivity to hydrogen generation and carbon monoxide oxidation.

Abstract: A hydrogen generation system is disclosed that includes a fuel reforming reactor generating a hydrogen-rich reformate gas at a temperature greater than 150 C, a pressure swing adsorption (PSA) hydrogen purification unit that separates the reformate gas into a relatively pure hydrogen stream and an off-gas stream, and a catalytic reactor down stream of the PSA unit that converts carbon monoxide (CO) and hydrogen (H2) contained in the relatively pure hydrogen stream into methane (CH4) and water vapor (H2O). The method of purification involves generating a hydrogen-rich reformate gas at a temperature greater than 150 C in a fuel reforming reactor, separating the reformate gas into a relatively pure hydrogen stream and an off-gas stream in a pressure swing adsorption (PSA) hydrogen purification unit, and converting carbon monoxide (CO) and hydrogen (H2) contained in the relatively pure hydrogen stream into methane (CH4) and water vapor (H2O) in a catalytic reactor down stream of the PSA unit.

Abstract: Materials that are useful for absorption enhanced reforming (AER) of a fuel, including absorbent materials and catalyst materials, and methods for using such materials for the conversion of carbon-based fuels to a H2-rich product gas. The materials can be fabricated by spray processing. The use of the materials in AER can produce a H2 product gas having a high H2 content and a low level of carbon oxides. The method for converting carbon-based fuels to a H2-rich product gas includes forming an intermediate gas product from the carbon-based fuel using a catalyst and contacting the intermediate gas product with an absorbent to absorb CO2. The absorbent can be regenerated while retaining a high absorption capacity.

Abstract: Materials that are useful for absorption enhanced reforming (AER) of a fuel, including absorbent materials and catalyst materials and methods for using the materials. The materials can be fabricated by spray processing. The use of the materials in AER can produce a H2 product gas having a high H2 content and a low level of carbon oxides.

Abstract: A man portable hydrogen source, the source comprising one or more hydrogen generating elements (2), an ignition control system (3) and a pressure vessel (1). Each hydrogen generating element comprises a pellet holder (7) provided with one or more recesses and a thermal insulation layer (9) to reduce heat transfer to adjacent hydrogen generating elements; wherein at least one recess contains a pellet (8) of a chemical mixture which on thermal decomposition evolves hydrogen gas; wherein the ignition control system comprises one or more ignitors (14), associated with an individual pellet (8), and activation means to activate the ignitors; and wherein the evolved hydrogen and hydrogen generating elements are contained within the pressure vessel.

Abstract: An attrition resistant precipitated bulk iron catalyst is prepared from iron oxide precursor and a binder by spray drying. The catalysts are preferably used in carbon monoxide hydrogenation processes such as Fischer-Tropsch synthesis. These catalysts are suitable for use in fluidized-bed reactors, transport reactors and, especially, slurry bubble column reactors.

Abstract: This invention relates to a process for conducting an equilibrium limited chemical reaction in a single stage process channel. A process for conducting a water shift reaction is disclosed. A multichannel reactor with cross flow heat exchange is disclosed.

Abstract: A method of reducing an amount of carbon monoxide in process fuel gas in a water gas shift converter with no methane formation. The method includes placing a high activity water gas shift catalyst system into a water gas shift converter; and passing the process fuel gas through the water gas shift converter in effective contact with the high activity water gas shift catalyst system and converting a portion of the carbon monoxide in the process fuel gas into carbon dioxide and hydrogen by a water gas shift reaction with no methane formation at a temperature in a range of about 200° C. to about 425° C.

Abstract: A method and catalysts and fuel processing apparatus for producing a hydrogen-rich gas, such as a hydrogen-rich syngas are disclosed. According to the method a CO-containing gas, such as a syngas, contacts a water gas shift (“WGS”) catalyst, in the presence of water, preferably at a temperature of less than about 450° C. to produce a hydrogen-rich gas, such as a hydrogen-rich syngas. Also disclosed is a water gas shift catalyst formulated from: a) at least one of Rh, Ni, Pt, their oxides and mixtures thereof, b) at least one of Cu, Ag, Au, their oxides and mixtures thereof; and c) at least one of K, Cs, Sc, Y, Ti, Zr, V, Mo, Re, Fe, Ru, Co, Ir, Pd, Cd, In, Ge, Sn, Pb, Sb, Te, La, Ce, Pr, Nd, Sm, Eu, their oxides and mixtures thereof. Another disclosed catalyst formulation comprises Rh, its oxides or mixtures thereof, Pt, its oxides or mixtures thereof and Ag, its oxides or mixtures thereof.

Abstract: The present invention relates to a method for making hydrogen comprising contacting in a water-gas shift reaction zone a feed comprising carbon monoxide and water under water-gas shift conditions with an effective catalytic amount of a catalyst comprising highly dispersed gold on a sulfated zirconia, and collecting from the water-gas shift reaction zone an effluent comprising hydrogen and carbon dioxide. The invention also provides a catalyst composition and a method of making the catalyst. In a specific embodiment the invention provides a method for carrying out the water-gas shift reaction in the fuel processor associated with a fuel cell.

Abstract: A method and catalysts for producing a hydrogen-rich syngas are disclosed. According to the method a CO-containing gas contacts a water gas shift (WGS) catalyst, optionally in the presence of water, preferably at a temperature of less than about 450° C. to produce a hydrogen-rich gas, such as a hydrogen-rich syngas. Also disclosed is a water gas shift catalyst formulated from: a) Pt, its oxides or mixtures thereof; b) Ru, its oxides or mixtures thereof; and c) at least one of Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Sc, Y, Ti, Zr, V, Mo, Mn, Fe, Co, Rh, Ir, Ge, Sn, Sb, La, Ce, Pr, Sm, and Eu. Another disclosed catalyst formulation comprises Pt, its oxides or mixtures thereof; Ru, its oxides or mixtures thereof; Co, its oxides or mixtures thereof; and at least one of Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Sc, Y, Ti, Zr, V, Mo, Mn, Fe, Rh, Ir, Ge, Sn, Sb, La, Ce, Pr, Sm, and Eu, their oxides and mixtures thereof.

Abstract: A method and catalysts and fuel processing apparatus for producing a hydrogen-rich gas, such as a hydrogen-rich syngas are disclosed. According to the method, a CO-containing gas, such as a syngas, contacts a platinum-free ruthenium-cobalt water gas shift (“WGS”) catalyst, in the presence of water and preferably at a temperature of less than about 450° C., to produce a hydrogen-rich gas, such as a hydrogen-rich syngas. Also disclosed is a platinum-free ruthenium-cobalt water gas shift catalyst formulated from: a) Ru, its oxides or mixtures thereof; b) Co, Mo, their oxides or mixtures thereof; and c) at least one of Li, Na, K, Rb, Cs, Ti, Zr, Cr, Fe, La, Ce, Eu, their oxides and mixtures thereof. The WGS catalyst may be supported on a carrier, such as any one member or a combination of alumina, zirconia, titania, ceria, magnesia, lanthania, niobia, zeolite, perovskite, silica clay, yttria and iron oxide. Fuel processors containing such water gas shift catalysts are also disclosed.

Abstract: A catalyst bed combination comprising a bed of a particulate copper-containing catalyst and, upstream of the catalyst bed, a guard bed in the form of shaped units formed from lead oxide particles and a particulate support material. The guard bed extends the life of the copper catalyst by absorbing halide contaminants in the process stream.

Abstract: A process for the treatment of synthesis gas to increase content of hydrogen and/or carbon monoxide in the gas comprising the step of contacting the synthesis gas with a catalyst comprising oxides of manganese and zirconium, which metals are present in a molar ratio Mn/Zr of between 0.05 to 5.00.

Abstract: Reactors and processes are disclosed that can utilize high heat fluxes to obtain fast, steady-state reaction rates. Porous catalysts used in conjunction with microchannel reactors to obtain high rates of heat transfer are also disclosed. Reactors and processes that utilize short contact times, high heat flux and low pressure drop are described. Improved methods of steam reforming are also provided.

Abstract: A process for catalytic reforming of a hydrocarbon feed stream containing H2O, CO2, CH4 and CO at levels such that the H2O/CH4 is less than 0.8 and the CO2/CH4 is greater than 0.5 and the feed stream further contains quantities of sulfur compounds up to about 20 ppm. The catalyst used in this process contains from about 0.5 percent to about 25 percent by weight of a calcium compound additive, from about 2 percent to about 30 percent by weight nickel, and from about 25 percent to about 98 percent by weight of an aluminum compound carrier, wherein substantially all of the calcium is combined with the alumina. The reforming process can be utilized to produce syngas, especially low hydrogen to carbon monoxide ratio syngas for applications such as iron ore reduction.

Abstract: A hydrogen producing apparatus comprising: a reforming section having a reforming catalyst which causes a reaction between a carbon-containing organic compound as a feedstock and water; a feedstock supply section for supplying the feedstock to the reforming section; a water supply section for supplying water to the reforming section; a heating section for heating the reforming catalyst; a shifting section having a shift catalyst which causes a shift reaction between carbon monoxide and water contained in a reformed gas supplied from the reforming section; and a purifying section having a purifying catalyst which causes oxidation or methanation of carbon monoxide contained in a gas supplied from the shifting section, wherein the shift catalyst comprises a platinum group metal and a metal oxide.

Abstract: This invention relates to a process for conducting an equilibrium limited chemical reaction in a single stage process channel. A process for conducting a water shift reaction is disclosed. A multichannel reactor with cross flow heat exchange is disclosed.

Abstract: Integrated Combustion Reactors (ICRs) and methods of making ICRs are described in which combustion chambers (or channels) are in direct thermal contact to reaction chambers for an endothermic reaction. Superior results were achieved for combustion chambers which contained a gap for free flow through the chamber. Particular reactor designs are also described. Processes of conducting reactions in integrated combustion reactors are described and results presented. Some of these processes are characterized by unexpected and superior results.

Abstract: The invention relates to a process for catalytic autothermal steam reforming of alcohols having two or more carbon atoms by directing a preheated educt or reactant mixture of the alcohols, oxygen and water or steam over a catalyst. The process is conducted in an adiabatic manner wherein the catalyst comprises at least one platinum group metal on an oxidic support selected from the group consisting of aluminum oxide, silicon dioxide, titanium dioxide or mixed oxides thereof and zeolites, and that the educt or reactant mixture contains additional hydrocarbons, which are reformed at the same time as the alcohols.

Abstract: Contemplated configurations and methods include a hydrogen pressure swing adsorption unit that receives a feed gas comprising a hydrogen production stream and a non-recycled hydrogen-containing waste stream.

Abstract: A fuel processor for producing a hydrogen-rich product gas suitable for direct use in fuel cell applications includes a housing, an annular shift/methanator reactor vessel at least one reactor vessel wall disposed within the housing and forming an outer annular space between the at least one reactor vessel wall and the housing. A combustion chamber having at least one combustion chamber wall and forming a first inner annular space between the at least one combustion chamber wall and the at least one reactor vessel wall is disposed in the interior space formed by the annular shift/methanator reactor vessel, and a reformer reactor vessel having at least one reformer vessel wall and forming a second inner annular space between the at least one reformer vessel wall and the at least one combustion chamber wall is disposed within the combustion chamber.

Abstract: A methanol reforming catalyst containing passivated copper and zinc oxide and/or alumina can be prepared by (1) precipitating or spray-drying a mixture of catalyst precursor components dissolved or suspended in a diluent in order to form a solid catalyst precursor in the form of powder or granules, (2) calcining and reducing the solid catalyst precursor obtained in stage (1), (3) passivating the reduced catalyst precursor obtained in stage (2) and (4) shaping the passivated catalyst precursor obtained in stage (3) to form the catalyst. A reduction in the volume shrinkage and an increase in the mechanical hardness during operation of the methanol reforming catalyst are achieved by the preparation process.

Abstract: Catalysts containing passivated copper and zinc oxide and/or alumina are prepared by (1) precipitating a mixture of catalyst precursor components dissolved or suspended in a diluent with anion-containing precipitating agents, washing and drying to form a solid catalyst precursor in the form of powder or granules, (2) calcining the solid catalyst precursor obtained in stage (1) to an anion content from the precipitating agent of from 0.1 to 2.5% by weight and (3) shaping and, if required, reducing and passivating the calcined catalyst precursor from stage (2) in any desired order to form the catalyst.

Abstract: The present specification disclosed a hydrogen refinement apparatus comprising a reformed gas feeding part containing at least a hydrogen gas and water vapor, and a reaction chamber equipped with a carbon monoxide shifting catalyst body downstream said reformed gas feeding part, wherein said carbon monoxide shifting catalyst body comprises a carrier supporting Pt, the carrier being composed of at least one metal oxide having a BET specific surface area of 10 m2/g or more, and a method for operating the apparatus. The present invention provides improved heat-resistance of the CO shifting catalyst body, and can operate stably even if the apparatus is activated and stopped repeatedly.

Abstract: Process for the production of synthesis gas, by means of catalytic partial oxidation or autothermal reforming of light hydrocarbons, which comprises partially oxidizing the hydrocarbon with oxygen coming from the reduction of at least one metal oxide selected from hexavalent chromium oxide, supported on an inert carrier and modified with an alkaline and/or earth-alkaline metal, and metal oxides capable of autonomously sustaining the catalytic partial oxidation reaction by means of redox cycles.

Abstract: A method and catalysts and fuel processing apparatus for producing a hydrogen-rich gas, such as a hydrogen-rich syngas are disclosed. According to the method a CO-containing gas, such as a syngas, contacts a water gas shift catalyst in the presence of water, preferably at a temperature of less than about 450° C. to produce a hydrogen-rich gas, such as a hydrogen-rich syngas.

Abstract: A method and catalysts and fuel processing apparatus for producing a hydrogen-rich gas, such as a hydrogen-rich syngas are disclosed. According to the method, a CO-containing gas, such as a syngas, contacts a platinum-free ruthenium-cobalt water gas shift (“WGS”) catalyst, in the presence of water and preferably at a temperature of less than about 450° C., to produce a hydrogen-rich gas, such as a hydrogen-rich syngas.

Abstract: A method and catalysts for producing a hydrogen-rich syngas are disclosed. According to the method a CO-containing gas contacts a water gas shift (WGS) catalyst, optionally in the presence of water, preferably at a temperature of less than about 450° C. to produce a hydrogen-rich gas, such as a hydrogen-rich syngas.

Abstract: Provided is a method and apparatus for producing hydrogen from an input gas stream containing carbon monoxide and steam that includes contacting the input gas stream with a catalyst. The catalyst contains an inorganic oxide support; a platinum group metal dispersed on the inorganic oxide support; and a methane suppressing dispersed on the inorganic oxide support. The methane suppressing component is selected from the group consisting of oxides of tin, oxides of gallium and combinations thereof. Also provided are preferred catalyst preparations.