Abstract: A composition that comprises a titanium compound, an iron compound, and a tungsten compound, wherein the titanium compound has a microcrystalline anatase structure and/or is obtained in the production of TiO2 according to the sulphate process, during hydrolysis of a solution which contains titanyl sulphate, and also in that the composition has a vanadium content, calculated as V, of less than 0.15 wt. % in relation to the solids content of the composition.

Abstract: An emission control catalyst composition comprising a supported bimetallic catalyst consisting of gold and a metal selected from the group consisting of platinum, rhodium, ruthenium, copper and nickel is disclosed. Also disclosed is a catalytic convertor comprising a substrate monolith coated with the emission control catalyst composition and a lean burn internal combustion engine exhaust gas emission treatment system comprising the catalytic convertor. A variety of processes for preparing the catalyst composition are claimed.

Abstract: The selective reduction-type catalyst effectively purifies nitrogen oxides contained in exhaust gas from a lean-burn engine such as a boiler, a gas turbine or a lean-burn engine, a diesel engine, even under high SV, as well as having small pressure loss, by supplying by spraying urea water or ammonia water, as a reducing component, to the selective reduction-type catalyst; and an exhaust gas purification apparatus along with an exhaust gas purification method using the same. The selective reduction-type catalyst for selectively reducing a nitrogen oxide by adding urea or ammonia as a reducing agent of the nitrogen oxide to exhaust gas discharged from a lean-burn engine, characterized by coating a catalyst layer including zeolite containing at least an iron element, and a composite oxide of silica, tungsten oxide, ceria and zirconia, as denitration components, at the surface of a monolithic structure-type substrate.

Abstract: A NOx storage component comprises caesium silicate (Cs2SiO3) and at least one platinum group metal. The invention also includes a NOx absorber catalyst comprising a NOx storage component according to the invention disposed on a substrate monolith; a method of treating exhaust gas containing NOx from a lean burn internal combustion engine comprising the steps of contacting a NOx storage component comprising caesium silicate (Cs2SiO3) and at least one platinum group metal with lean exhaust gas containing NOx to adsorb NOx thereon; and periodically desorbing adsorbed NOx by contacting the NOx storage component with stoichiometric or rich exhaust gas; and a method of making a NOx storage component according to the invention comprising the steps of combining and reacting an aqueous salt of at least one platinum group metal, an aqueous caesium salt and a source of silica.

Abstract: A metal catalyst is formed by vaporizing a quantity of metal and a quantity of carrier forming a vapor cloud. The vapor cloud is quenched forming precipitate nanoparticles comprising a portion of metal and a portion of carrier. The nanoparticles are impregnated onto supports. The supports are able to be used in existing heterogeneous catalysis systems. A system for forming metal catalysts comprises means for vaporizing a quantity of metals and a quantity of carrier, quenching the resulting vapor cloud and forming precipitate nanoparticles comprising a portion of metals and a portion of carrier. The system further comprises means for impregnating supports with the nanoparticles.

Abstract: The invention relates to a composition essentially consisting of a zirconia-ceria mixed oxide, with a zirconia content of at least 40 wt. % and, after 4 hours of calcination at 1000° C., a specific surface area of at least 25 m2/g and a quantity of mobile oxygen between 200° C. and 400° C. of at least 0.5 ml O2/g. Said composition is produced using a method wherein a mixture of cerium and zirconium compounds is continuously reacted with a basic compound in a reactor, with a maximum residence time of the reactive medium in the mixture zone of the reactor of 100 milliseconds; and the precipitate is heated then brought into contact with a surfactant before being calcinated.

Abstract: Described is a nitrogen oxide storage catalyst comprising: a substrate; a first washcoat layer provided on the substrate, the first washcoat layer comprising a nitrogen oxide storage material, a second washcoat layer provided on the first washcoat layer, the second washcoat layer comprising a hydrocarbon trap material, wherein the hydrocarbon trap material comprises substantially no element or compound in a state in which it is capable of catalyzing selective catalytic reduction, preferably wherein the hydrocarbon trap material comprises substantially no element or compound in a state in which it is capable of catalyzing a reaction wherein nitrogen oxide is reduced to N2, said catalyst further comprising a nitrogen oxide conversion material which is either comprised in the second washcoat layer and/or in a washcoat layer provided between the first washcoat layer and the second washcoat layer.

Abstract: A process for the preparation of a composition comprising Al-, Ce- and Zr-oxides, which process comprises the steps of (a) preparing an aqueous solution of a mixture of metal salts of cerium, zirconium and aluminium, which aqueous solution optionally comprises one or more salts of the Rare Earth Metals other than cerium, (b) adding to the solution obtained a base at temperatures from 0° C. to 95° C. and precipitating the mixed metal salts in the form of hydroxides or oxy-hydroxides, (d) treating the aqueous suspension obtained in step (b) with a surfactant, and (e) isolating the precipitate obtained in step (d) and treating said precipitate at a temperature from 450° C. to 1200° C., which process is characterized in that the alumina content is in the range from 35 to 80% by weight, and the surface area (BET) of the composition obtained, measured according to DIN (Deutsche Industrie Norm) 66131 after calcining for 2 hours at 1100° C.

Abstract: The present invention provides methods and designs of enclosed-channel reactor system for manufacturing catalysts or supports. Both of the configuration designs force the gaseous precursors and purge gas flow through the channel surface of reactor. The precursors will transform to thin film or particle catalysts or supports under adequate reaction temperature, working pressure and gas concentration. The reactor body is either sealed or enclosed for isolation from atmosphere. Another method using super ALD cycles is also proposed to grow alloy catalysts or supports with controllable concentration. The catalysts prepared by the method and system in the present invention are noble metals, such as platinum, palladium, rhodium, ruthenium, iridium and osmium, or transition metals such as iron, silver, cobalt, nickel and tin, while supports are silicon oxide, aluminum oxide, zirconium oxide, cerium oxide or magnesium oxide, or refractory metals, which can be chromium, molybdenum, tungsten or tantalum.

Abstract: The present disclosure relates to a substrate comprising nanomaterials for treatment of gases, washcoats for use in preparing such a substrate, and methods of preparation of the nanomaterials and the substrate comprising the nanomaterials. More specifically, the present disclosure relates to a substrate comprising nanomaterial for three-way catalytic converters for treatment of exhaust gases.

Abstract: The invention relates to a composition essentially consisting of ceria-zirconia mixed oxide, with a ceria content of at least 60 wt. % and, after 4 hours of calcination at 1000° C., a specific surface area of at least 15 m2/g and a quantity of mobile oxygen between 200° C. and 400° C. of at least 0.7 ml 02/g. Said composition is produced using a method wherein a mixture of cerium and zirconium compounds is continuously reacted with a basic compound in a reactor, with a maximum residence time of the reactive medium in the mixture zone of the reactor of 100 milliseconds; and the precipitate is heated then brought into contact with a surfactant before being calcinated.

Abstract: Catalyst/catalyst support composition essentially consist of oxides of zirconium, cerium and lanthanum and of another rare earth selected from among yttrium, gadolinium and samarium, having a proportion of the lanthanum oxide and the oxide of the other rare earth of at least 15% and specific surfaces of at least 40 m2/g and at least 15 m2/g after calcination respectively for 4 hours at 1,000° C. and 10 hours at 1,150° C.; after calcination for 10 hours at 1,200° C. these have a surface of at least 7 m2/g and such surface is at least 5 m2/g for an embodiment in which after 10 hours of calcination at 1,150° C. the composition is in the form of a pure solid solution.

Abstract: A method of steam reforming where a reaction occurs in which an oxygenated feed contacts a catalyst to produce hydrogen. The catalyst of the reaction comprises a metal/metal promoter on a nickel/transition metal blend catalyst supported on a high-energy lattice metal oxide.

Abstract: A catalytically active component is provided which comprises particles containing a metal oxide such as silica, metal or metalloid ions such as ions that include boron, and a catalyst. When introduced into the membrane electrode assembly of a fuel cell, the particles increase peroxide radical resistance in a membrane electrode.

Abstract: Catalytic articles, systems and methods for treating exhaust gas streams are described. A catalytic article comprising a wall flow filter having gas permeable walls, a hydrolysis catalyst, an optional soot oxidation catalyst, a selective catalytic reduction catalyst permeating the walls, an ammonia oxidation catalyst and an oxidation catalyst to oxidize CO and hydrocarbons is described. Methods of treating exhaust gas streams comprising soot, an ammonia precursor such as urea, ammonia, NOx, CO and hydrocarbons are also provided.

Abstract: An exhaust gas controlling catalyst includes zirconia particles; ceria particles which contact the zirconia particles, of which a mean particle size is smaller than a mean particle size of the zirconia particles; and an active metal that is supported on at least the ceria particles in a dispersed manner.

Abstract: A method for providing a catalyst on a substrate is disclosed comprising providing a first washcoat comprising a soluble washcoat salt species, a polar organic solvent, and an insoluble particulate material, contacting the first washcoat with a substrate to form a coated substrate, and then contacting the coated substrate with a second washcoat comprising an oxide or an oxide-supported catalyst to physisorb, chemisorb, bond, or otherwise adhere the oxide or the oxide-supported catalyst to the coated substrate. Also disclosed is a catalyst on a substrate comprising: a substrate; an anchor layer comprising a soluble washcoat salt species, a polar organic solvent, and an insoluble particulate material; and a second layer comprises an oxide or an oxide-supported catalyst. The catalyst on a substrate can be in either green or fired form.

Abstract: The invention relates to a catalytically active particulate filter which, in addition to the properties typical of particulate filters, has hydrogen sulphide block function, and to a process for removing nitrogen oxides and particulates from the exhaust gas of internal combustion engines operated predominantly under lean conditions (so-called “lean-burn engines”) using the inventive catalytically active particulate filter. This particulate filter comprises a filter body, a copper compound and an oxidation-catalytic active coating which comprises at least one catalytically active platinum group metal. The copper compound is in a second coating applied to the filter body. The two functional coatings may be applied to the filter body consecutive in the direction of flow, i.e. zoned, or layered one on top of the other.

Abstract: The present invention is directed to a process for the production of supported transition metals with high dispersion. The latter are deposited onto refractory oxides without using a further liquid solvent. Hence, according to this dry procedure no solvent is involved which obviates certain drawbacks connected with wet ion exchange, impregnation or other metal addition processes known in the art.

Abstract: An exhaust emission control catalyst disclosed herein is equipped with a rhodium catalytic layer and a platinum catalytic layer, and is characterized in that a relationship between a mole average (X) of a Pauling's electronegativity that is calculated as to elements included in the rhodium catalytic layer except platinum group elements and oxygen and a mole average (Y) of a Pauling's electronegativity that is calculated as to elements included in the platinum catalytic layer except platinum group elements and oxygen is 1.30?X?1.45 and 1.47?Y?2.0. According to this exhaust emission control catalyst, an interlayer transfer of platinum and/or rhodium and the alloying of platinum and/or rhodium are suppressed during use of the catalyst, and high exhaust gas purification performance can be exerted.

Abstract: A gas-reforming catalyst is modified to obtain stability in high temperature. The catalyst uses ?-Al2O3 as a carrier and is nano-porous. Hence, reaction surface is greatly broadened; and platinum contained inside does not become bigger after times of use. The catalyst does not deposit carbon and has long life. The stability of the catalyst can be still remained even at a temperature higher than 800° C.

Abstract: An internal combustion engine in which an SOx trap catalyst (13) for trapping SOx contained in the exhaust gas contains an oxygen adsorbing and releasing material (54) which can adsorb SO2 contained in the exhaust gas and an SOx storage material (55) which can store SOx in the form of sulfates. The SO2 which is contained in the exhaust gas is chemically adsorbed at the oxygen adsorbing and releasing material (54) without being oxidized. If the temperature of the SOx trap catalyst (13) becomes higher than the start temperature of adsorbed SO2 movement, the SO2 which is chemically adsorbed at the oxygen adsorbing and releasing material (54) is oxidized and stored in the form of sulfates in the SOx storage material (55).

Abstract: A method of manufacturing a catalyst body which includes: combining one or more inorganic components with an inorganic binder, and optionally with an organic binder, to form a mixture, the one or more inorganic components comprising a primary phase material being zeolite, or CeO2—ZrO2, or a combination; forming the mixture into a shaped body; firing the shaped body to allow the inorganic binder to bind the one or more inorganic components; impregnating the shaped body with a source of a reducing or oxidizing element; and heating the impregnated shaped body to form a redox oxide from the source, the redox oxide being supported by the shaped body.

Abstract: Core-shell nanoparticulate compositions and methods for making the same are disclosed. In some embodiments core-shell nanoparticulate compositions comprise transition metal core encapsulated by metal oxide shell. Methods of catalysis comprising core-shell nanoparticulate compositions of the invention are disclosed. Compositions comprising core-shell nanoparticles displayed on a metal-oxide support and methods for preparing the same are also disclosed. In some embodiments compositions comprise core-shell nanoparticles displayed as a substantially single layer superposed on a metal oxide support. Methods of catalysis employing the supported core-shell nanoparticles are disclosed.

Abstract: Catalytic compositions and processes are disclosed for economical conversions of lower alkane hydrocarbons. Broadly, the present invention discloses solid compositions containing mixed metal oxides that exhibit catalytic activity for ammoxidation of lower alkane hydrocarbons to produce an unsaturated nitrile in high yield. Generally, these solid oxide compositions comprise, as component elements, molybdenum (Mo), vanadium (V) niobium (Nb) and at least one active element selected from the group consisting of the elements having the ability to form positive ions. Mixed metal oxide catalytic compositions advantageously comprise one or more crystalline phases at least one of which phases has pre-determined unit cell volume and aspect ratio. Also described are methods for forming the improved catalysts having the desired crystalline structure and ammoxidation processes for conversion of lower alkanes.

Abstract: An exhaust gas purifying catalyst that contains a first oxygen storage material on which no noble metal is supported and which has a pyrochlore phase type regular array structure, and a second oxygen storage material which has a higher oxygen storage rate and a lower oxygen storage capacity than the first oxygen storage material and on which a platinum group noble metal is supported.

Abstract: Provided is a catalyst including: a support including titanium oxide; an active catalyst component including vanadium oxide; and a co-catalyst including antimony and cerium, in which the catalyst is included in a deNox reduction reaction that decomposes nitrogen oxide. The catalyst may improve sulfur poisoning tolerance characteristics while improving the deNox efficiency at a temperature in a wide range from low temperature to high temperature.

Abstract: A rhodium-loading solution characterized by comprising rhodium atoms and an organic base in a molar ratio of 1:0.5-35.

Abstract: An exhaust gas purifying catalyst (1) of the present invention includes anchor/promoter simultaneous enclosure particles (5) including catalyst units (13) which contain: noble metal particles (8); and anchor particles (9) as an anchor material of the noble metal particles (8) supporting the noble metal particles (8); promoter units (14) which are provided not in contact with the noble metal particles (8) and contain first promoter particles (11) having an oxygen storage and release capacity; and an enclosure material (12) which encloses both the catalyst units (13) and the promoter units (14), and separates the noble metal particles (8) and the anchor particles (9) in the catalyst units (13) from the first promoter particles (11) in the promoter units (14). The exhaust gas purifying catalyst (1) further includes second promoter particles (6) which have the oxygen storage and release capacity, and are not enclosed in the anchor/promoter simultaneous enclosure particles (5) by the enclosure material (12).

Abstract: A catalytic article for decomposition of a volatile organic compound includes a porous support body, a plurality of active centers formed on the support body and adapted for catalytic decomposition of the volatile organic compound, and a plurality of capture centers bound to the support body. Each of the active centers is composed of one of a noble metal, a transition metal oxide, and the combination thereof. Each of the capture centers includes at least one functional group that is adapted for attracting or binding the volatile organic compound. A method for preparing the catalytic article is also disclosed.

Abstract: A Rh-including catalyst layer of an upstream catalyst 3 includes Rh-doped CeZr-based mixed oxide and Rh-loading CeZr-based mixed oxide as oxygen storage/release materials. A Rh-including catalyst layer of a downstream catalyst 5 includes only Rh-doped CeZr-based mixed oxide as an oxygen storage/release material. The content of the oxygen storage/release materials included in the Rh-including catalyst layer of the upstream catalyst 3 is smaller than that of the downstream catalyst 5. The Rh-doped CeZr-based mixed oxide of the upstream catalyst 3 shows a particle size distribution having a peak particle size smaller than that of the Rh-doped CeZr-based mixed oxide of the downstream catalyst 5.

Abstract: A process for replacing the continuous phase of a nanoparticle dispersion with a less polar phase, includes filtering the dispersion through a semi-permeable membrane filter to remove the continuous phase, and introducing a less polar phase.

Abstract: A method of making a metal oxide nanoparticle comprising contacting an aqueous solution of a metal salt with an oxidant. The method is safe, environmentally benign, and uses readily available precursors. The size of the nanoparticles, which can be as small as 1 nm or smaller, can be controlled by selecting appropriate conditions. The method is compatible with biologically derived scaffolds, such as virus particles chosen to bind a desired material. The resulting nanoparticles can be porous and provide advantageous properties as a catalyst.

Abstract: The invention provides a catalyst for catalytically removing three components, which are carbon monoxide, hydrocarbons and nitrogen oxides, from combustion exhaust gas generated by combusting fuel at around the stoichiometric air to fuel ratio. The catalyst includes: (A) a first catalyst component including at least rhodium, platinum, or palladium in a content of 0.01 to 0.5% by weight; and (B) a second catalyst component, which is the remainder, including a composite oxide or a mixed oxide including (a) at least zirconium oxide or titanium oxide, and (b) an oxide of at least praseodymium, yttrium, neodymium, tungsten, niobium, silicon, or aluminum, wherein the content of the oxide (a) in the composite oxide or the mixed oxide is in a range of 70 to 95% by weight. The invention further provides a two-layer catalyst that includes a surface catalyst layer containing the above-mentioned catalyst.

Abstract: Aspects of the invention relate to a method of treating a gas stream generated by a motorcycle, the method comprising: contacting a gas stream containing hydrocarbons, carbon monoxide and nitrogen oxides and generated by a motorcycle under both rich and lean engine operating conditions with a base metal catalyst composition, thereby removing at least a part of the hydrocarbons, carbon monoxide and nitrogen oxides in gas stream. The base metal catalyst composition comprises a support including at least 10% by weight of reducible ceria, and about 3 to about 7 wt % MnO and about 8 to about 22 wt % CuO on the reducible ceria support. The base metal catalyst composition is effective to promote a steam reforming reaction of hydrocarbons and a water gas shift reaction to provide H2 as a reductant to abate NOx.

Abstract: This invention concerns a procedure for the formation of a bimetallic composition by means of the subsequent depositing of Co(0) and Pd(0) on an inert support, a composition obtained by means of said procedure and the use of said bimetallic composition as a catalyst. Another aspect of this invention is a catalytic device that includes said bimetallic composition.

Abstract: A double-layer three-way catalyst for purification of the exhaust gases from internal combustion engines which has excellent activity and thermal stability is described. The catalyst contains active aluminum oxide and a first cerium/zirconium mixed oxide which are both catalytically activated with palladium in the first layer applied to a catalyst support. In the second layer which is in direct contact with the exhaust gas, the catalyst likewise contains an active aluminum oxide and a second cerium/zirconium mixed oxide which are both catalytically activated with rhodium. The second cerium/zirconium mixed oxide has a higher zirconium oxide content than the first mixed oxide.

Abstract: A catalytic material including particles formed of a catalytic core material having a thermally resistant porous shell coated over the catalytic core material. An oxygen storage material is dispersed within the thermally resistant porous shell. In an example, the oxygen storage material is ceria. The catalytic material can further include a catalytic support, wherein the particles are deposited on the catalytic support. The catalytic support can be a powdered oxide including a material selected from the group consisting of alumina, silica, zirconia, niobia, ceria, titania, and combinations thereof. The catalytic core can include an element selected from the group consisting of Pt, Pd, Rh, Co, Ni, Mn, Cu, Fe, Au, Ag, and combinations thereof. The porous shell can be selected from materials consisting of alumina, baria, ceria, magnesia, niobia, silica, titania, yttria, and combinations thereof.

Abstract: The present subject matter provides a method of preparing a multicomponent metal-hybrid nanocomposite using co-gasification, in which a multicomponent metal-hybrid nanocomposite can be prepared by a one-step process without using a complicated process including the steps of supporting-drying-calcining-annealing and the like at the time of preparing a conventional alloy catalyst, and provides a multicomponent metal-hybrid nanocomposite prepared by the method. The method is advantageous in that a multicomponent metal-hybrid nanocomposite can be synthesized by a simple process of simultaneously gasifying two kinds of metal precursors, and in that an additional post-treatment process is not required.

Abstract: A catalyst support which may be used to support various catalysts for use in reactions for hydrogenation of carbon dioxide including a catalyst support material and an active material capable of catalyzing a reverse water-gas shift (RWGS) reaction associated with the catalyst support material. A catalyst for hydrogenation of carbon dioxide may be supported on the catalyst support. A method for making a catalyst for use in hydrogenation of carbon dioxide including application of an active material capable of catalyzing a reverse water-gas shift (RWGS) reaction to a catalyst support material, the coated catalyst support material is optionally calcined, and a catalyst for the hydrogenation of carbon dioxide is deposited on the coated catalyst support material. A process for hydrogenation of carbon dioxide and for making syngas comprising a hydrocarbon, esp. methane, reforming step and a RWGS step which employs the catalyst composition of the present invention and products thereof.

Abstract: Described is a process for the production of mixed oxide particles. The process comprises providing a mixture comprising a solvent, one or more precursor compounds of ceria, one or more precursor compounds of zirconia, and one or more precursor compounds of one or more rare earth oxides other than ceria and/or one or more precursor compounds of yttria; forming an aerosol of the mixture; and pyrolyzing the aerosol of to obtain mixed oxide particles. The content of the rare earth oxides other than ceria and/or of yttria in the mixed oxide particles is comprised in the range of from 0.1 to 4.9 wt.-% based on the total weight of the rare earth oxides, yttria, and zirconia contained in the mixed oxide particles. Also describes are mixed oxide particles obtained from flame spray pyrolysis and to their use as an oxygen storage component, a catalyst, and/or as a catalyst support.

Abstract: Provided is a method for producing a catalyst for purification of exhaust gas, including the steps of: adding Zr ions to a solution containing a platinum hydroxide polymer; diluting the solution to which the Zr ions are added by using an aqueous ammonium acetate solution; immersing a support made of Al2O3, SiO2, CeO2, ZrO2, or a composite oxide of any ones of these oxides in the diluted solution, followed by heating at 60 to 70° C., to thereby support the platinum hydroxide polymer on the support; and calcining the support, on which the platinum hydroxide polymer is supported, at 150 to 800° C.

Abstract: The composition according to the invention is based on zirconium oxide, cerium oxide and at least one oxide of a rare earth other than cerium, in a proportion, by weight, of zirconium oxide of at least 5% and of cerium oxide of at most 90%, and it is characterized in that it additionally comprises silicon oxide in an amount, by weight, of between 0.1% and 2%. This composition may be used in catalysis, in particular in systems for treating the exhaust gases of internal combustion engines.

Abstract: A catalyst for reforming hydrocarbons may include a catalytically active amount of nickel or nickel oxide dispersed on a metal oxide support. The metal oxide support may be of a single-metal oxide of a first metal or a complex-metal oxide of the first metal and a second metal. A co-catalyst of magnesium oxide (MgO) may anchor the nickel or nickel oxide onto the metal oxide support.

Abstract: A process for hydrogenating highly unsaturated hydrocarbons to less unsaturated hydrocarbons wherein production of saturated hydrocarbons is minimized. The process utilizes catalyst including Ce2O3, MgO, and an inorganic support, and optionally palladium, optionally silver, and/or an optional alkali metal.

Abstract: Provided is a catalyst for purifying an exhaust gas, the catalyst excelling in catalytic performance and oxygen storage capacity. The catalyst for purifying an exhaust gas is a catalyst for purifying an exhaust gas which includes a ceria-zirconia composite oxide having a pyrochlore structure and a ceria-zirconia composite oxide having a cubic crystal structure, wherein at least a part of the ceria-zirconia composite oxide is composited with the ceria-zirconia composite oxide.

Abstract: Steam reforming a hydrocarbon feed such as liquefied petroleum gas is conducted in the presence of a catalyst comprising a precious metal such as rhodium on a support comprising ceria, zirconia and praseodymium oxide.

Abstract: A high NOx-purifying performance at high temperature conditions is achieved with a small amount of precious metal used. An exhaust gas-purifying catalyst includes a substrate, a lower layer formed on the substrate and including a first composite oxide, palladium and platinum, and an upper layer formed on the lower layer and including a second composite oxide and rhodium. The first composite oxide includes cerium, zirconium, and an element selected from the group consisting of rare-earth elements other than cerium and alkaline-earth elements. A mass ratio of platinum with respect to palladium falls within a range of 1/50 to 1/20. The second composite oxide includes zirconium and an element selected from the group consisting of rare-earth elements other than cerium and alkaline-earth elements and has an atomic ratio of cerium with respect to zirconium smaller than that of the first composite oxide.

Abstract: A NOx absorber catalyst comprising an extruded solid body comprises either: (A) 10-95% by weight of at least one binder/matrix component; and 5-90% by weight of a zeolitic molecular sieve, a non-zeolitic molecular sieve or a mixture of any two or more thereof, which catalyst comprising at least one metal comprising (a) at least one precious metal; and (b) at least one alkali metal or at least one alkaline earth metal, wherein (a) and (b) are carried in one or more coating layer(s) on a surface of the extruded solid body; or (B) 10-95% by weight of at least one binder/matrix component; and 5-80% by weight optionally stabilized ceria, which catalyst comprising at least one metal comprising (a) at least one precious metal; and (b) at least one alkali metal or at least one alkaline earth metal.

Abstract: A cerium-zirconium composite metal oxide having improved durability at high temperature and a stable oxygen storage capacity is provided. The cerium-zirconium composite metal oxide is characterized in that the total mole number of Ce and Zr is at least 85% based on the total mole number of metal in the composite metal oxide, a molar ratio Ce/Zr is within a range from 1/9 to 9/1, and an isoelectric point of the composite metal oxide is more than 3.5. Preferably, the molar ratio Ce/Zr is within a range from 3/7 to 7/3 and the isoelectric point is within a range from 3.8 to 5.0, and the cerium-zirconium composite metal oxide contains a rare earth metal (excluding Ce) in a concentration of less than 15% by mole based on the total mole number of metal in the composite metal oxide. Also the present invention provides a cerium-zirconium composite metal oxide, characterized in that CeO2 forms a core surrounded by ZrO2.