Abstract: Disclosed in certain embodiments is a sulfur tolerant catalytic system that includes a catalytic material coated onto a substrate. Certain embodiments are directed to a method of preparing a sulfur-tolerant catalyst.

Abstract: The present disclosure provides an exhaust gas purification catalyst improved in OSC performance while maintaining an exhaust gas purification performance, which comprises a substrate and at least one catalyst layer formed on the substrate, wherein an uppermost catalyst layer contains a catalyst metal, a first OSC material having a pyrochlore structure, and a second OSC material having a higher oxygen storage/release rate than the first OSC material, wherein the uppermost catalyst layer consists of an upstream catalyst layer and a downstream catalyst layer, and wherein a proportion of a mass of the second OSC material based on a total mass of the first OSC material and the second OSC material is in a specific range in each of the upstream catalyst layer and the downstream catalyst layer.

Abstract: Methods are provided for emissions control of a vehicle. In one example, a catalyst may include a cerium-based support material and a transition metal catalyst loaded on the support material, the transition metal catalyst including nickel and copper, wherein nickel in the transition metal catalyst is included in a monatomic layer loaded on the support material. In some examples, limiting nickel to the monatomic layer may mitigate extensive transition metal catalyst degradation ascribed to sintering of thicker nickel washcoat layers. Further, by utilizing the cerium-based support material, side reactions involving nickel in the transition metal catalyst with other support materials may be prevented.

Abstract: A three-way catalyst article, and its use in an exhaust system for internal combustion engines, is disclosed. The catalyst article for treating exhaust gas comprising: a substrate comprising an inlet end and an outlet end with an axial length L; a first catalytic region comprising a first platinum group metal (PGM) component and a first PGM support material, wherein the first catalytic region comprises up to 5 wt. % Sn.

Abstract: Provided are an LNT layered catalyst for a lean burn gasoline engine having an enhanced NOx storage rate and capable of developing a higher NOx purification rate, and an exhaust gas purification apparatus using the same, the LNT layered catalyst including a substrate, a first catalyst layer including ceria-alumina particles carrying Pt, Pd, and BaO, and a second catalyst layer including ceria-alumina particles carrying Pt and Rh, in which a content of Pt in the first catalyst layer is 0.45 to 0.85 mass %; among Pt included in the first catalyst layer, a content proportion in a first depth region is 88 to 90 mass %, and a content proportion in a second depth region is 10 to 12 mass %; a content of Ba in the first catalyst layer is 4 to 11 mass %; and the second catalyst layer is substantially free from Ba.

Abstract: The invention discloses a catalyst for removing volatile organic compounds and a preparation method therefor. In the catalyst, aluminum oxide modified by iron, cobalt and nickel is used as a carrier, cordierite honeycomb ceramic is used as a matrix, and an extremely low content of a mixture of platinum and palladium is used as an active component; a molar ratio of platinum to palladium is 0-1:0-9, and an amount of the mixture of platinum and palladium accounts for 0.01% to 0.05% of a mass of the matrix; and an amount of the carrier accounts for 3% to 5% of the mass of the matrix.

Abstract: The present invention relates to a honeycomb catalytic converter, including: a honeycomb structured body in which multiple through-holes are arranged longitudinally in parallel with one another with a partition wall therebetween; and Pd and Rh supported on the partition walls of the honeycomb structured body, wherein the honeycomb structured body is an extrudate containing a ceria-zirconia complex oxide and alumina, a Pd-carrying region where only Pd is supported is formed on the partition walls within a predetermined width from one end of the honeycomb structured body, and a Rh-carrying region where only Rh is supported is formed on the partition walls within a predetermined width from the other end of the honeycomb structured body, and the Pd-carrying region extends to at least 50% of the length of the honeycomb structured body, and the Rh-carrying region extends to at least 20% of the length of the honeycomb structured body.

Abstract: A three-way catalyst article, and its use in an exhaust system for internal combustion engines, is disclosed. The catalyst article for treating exhaust gas comprising: a substrate comprising an inlet end and an outlet end with an axial length L; a first catalytic region comprising a first platinum group metal (PGM) component and a first oxygen storage capacity (OSC) material, wherein the first OSC material has a fresh specific surface area (SSA) of at least 10 m2/g; and wherein the first OSC material has an SSA difference of no more than 30 m2/g between the fresh first OSC material and the aged first OSC material.

Abstract: The present invention relates to a mixed oxide of aluminium, of zirconium, of cerium, of lanthanum and optionally of at least one rare-earth metal other than cerium and lanthanum that makes it possible to prepare a catalyst that retains, after severe ageing, a good thermal stability and a good catalytic activity. The invention also relates to the process for preparing this mixed oxide and also to a process for treating exhaust gases from internal combustion engines using a catalyst prepared from this mixed oxide.

Abstract: The present invention provides a method of producing a honeycomb structured body having excellent mechanical strength.

Abstract: The present invention provides a method of producing a honeycomb structured body having excellent mechanical strength.

Abstract: This invention provides a preparation method of a catalyst for preferential oxidization of CO in a hydrogen-enriched atmosphere, and a catalyst product obtained from the method and its applications thereof. Particularly, in this invention, a wide-temperature catalyst for preferential oxidization of CO in a hydrogen-enriched atmosphere is obtained by depositing one or more of an iron oxide, cobalt oxide, and nickel oxide as a promoter onto the surface of a supported Pt-group noble metal catalyst precursor via chemical vapor deposition or atomic layer deposition. In the wide-temperature catalyst, the active noble metal component has a content of 0.1 to 10 wt %, and the promoter has a content of 0.1 to 10 wt % in terms of the metal element thereof.

Abstract: Certain selective catalytic reduction (SCR) articles, systems and methods provide for high NOx conversion while at the same time low N2O formation. The articles, systems and methods are suitable for instance for the treatment of exhaust gas of diesel engines. Certain articles have zoned coatings containing copper-containing molecular sieves disposed thereon, where for example a concentration of catalytic copper in an upstream zone is lower than the concentration of catalytic copper in a downstream zone.

Abstract: An exhaust gas treatment system is provided for an exhaust system of an internal combustion engine. The exhaust gas treatment system includes a plurality of SCR catalytic converter units (32, 34, 36) connected in parallel to one another. At least one SCR catalytic converter unit (32, 34, 36) of the SCR catalytic converter units (32, 34, 36) is connected in parallel to one another can optionally be released and blocked for the flow of exhaust gas.

Abstract: The invention relates to a method for improving the efficiency of an SCR system of an exhaust gas aftertreatment system (5) of an internal combustion engine (1), and to an internal combustion engine (1), wherein an operating medium is metered in upstream of the SCR catalytic converter (2) of the SCR system in a normal operating mode, wherein the operating medium comprises a reducing agent or can be converted into a reducing agent, wherein the reducing agent is stored at least temporarily in an SCR catalytic converter (2) of the SCR system, wherein the method comprises the following steps: operating of the internal combustion engine (1) in the normal operating mode, defining of a determined control value (6) by way of determining of the mass of an exhaust gas component which is measured overall at a point in the course of the exhaust gas aftertreatment system (5) during a first measurement window, determining of a calculated control value (7) by way of calculating of the mass of the exhaust gas component which

Abstract: A catalyst material for abatement of exhaust gas emissions from a lean burn engine is provided, the catalyst material including a metal-exchanged SAPO-34 material, and an oxide layer at least partially covering an outside surface of the SAPO-34 material, wherein the oxide layer is not substantially blocking the pores of the SAPO-34 material.

Abstract: An oxidation catalyst for treating an exhaust gas from a diesel engine, which oxidation catalyst comprises: a first washcoat region comprising platinum (Pt), manganese (Mn) and a first support material; a second washcoat region comprising a platinum group metal (PGM) and a second support material; and a substrate having an inlet end and an outlet end; wherein the second washcoat region is arranged to contact the exhaust gas at the outlet end of the substrate and after contact of the exhaust gas with the first washcoat region.

Abstract: A monolithic catalyst used for a carbon dioxide hydrogenation reaction and a method for preparing the same. The catalyst comprises a carrier, a coating, and active components. The carrier is a honeycomb ceramic. The coating and the active components are separately applied to honeycomb ceramic hole walls from inside to outside. Moreover, each of the honeycomb ceramic holes is divided into an upper segment and a lower segment, and different active components are separately loaded on the two segments. The method for preparing the monolithic catalyst comprises first applying a coating to a honeycomb ceramic by means of impregnation to obtain a coating-containing carrier, and then applying active components to an upper segment and a lower segment of the coating-containing carrier successively by means of impregnation to obtain the monolithic catalyst.

Abstract: An exhaust gas purifying catalyst for 2-stroke general-purpose engines, which is characterized in that: the exhaust gas purifying catalyst includes a base and a coat layer on the base; the coat layer contains noble metals and metal oxides; the noble metals include palladium and one or more elements selected from among platinum and rhodium; the zirconia content in the coat layer is 0.07 mole or less per 100 g of the metal oxides contained in the coat layer; and the total content of one or more metal oxides selected from among lanthana and alkaline earth metal oxides in the coat layer is 0.05 mole or more per 100 g of the metal oxides contained in the coat layer.

Abstract: This invention relates to a catalyst system comprising (a) at least one layer of a first catalyst comprising a dehydrogenation active metal on a solid support; (b) at least one layer of a second catalyst comprising a metal oxide; and (c) at least one layer of a third catalyst comprising a transition metal on an inorganic support; wherein the at least one layer of a second catalyst is sandwiched between the at least one layer of a first catalyst and the at least one layer of a third catalyst; and a process comprising contacting a hydrocarbon feed with the catalyst system.

Abstract: A process for the preparation of an extra-framework metal-containing aluminosilicate zeolite involves the steps of: (a) forming a reactant mixture A comprising (i) an aqueous slurry of an aluminosilicate zeolite in a H+-form, and (ii) a metal containing compound or free metal, wherein the mixture does not comprise ammonia, ammonium hydroxide or an ammonium salt, and (b) reacting the metal containing compound or free metal with the aluminosilicate zeolite in a H+-form in reactant mixture A and forming a product mixture B, a reaction mixture comprising the extra-framework metal-containing aluminosilicate zeolite. The metal comprises one or more of copper, iron, manganese, nickel and palladium. The step of reacting the metal with the aluminosilicate zeolite in a H+-form is performed in a single exchange. The extra-framework metal-containing aluminosilicate zeolite can then be used directly in forming a washcoat that can be applied to a support.

Abstract: The present invention provides crystalline aluminosilicate zeolites having a maximum pore size of eight tetrahedral atoms, wherein the zeolite has a total proton content of less than 2 mmol per gram. The zeolite may comprise 0.1 to 10 wt.-% of at least one transition metal, calculated as the respective oxide and based on the total weight of the zeolite. It may furthermore comprise at least one alkali or alkaline earth metal in a concentration of 0 to 2 wt.-%, calculated as the respective metal and based on the total weight of the zeolite. The zeolites may be used for the removal of NOx from automotive combustion exhaust gases.

Abstract: The invention relates to a light extraction substrate having a light extraction layer. The light extraction layer includes boron, boroate, and/or borosilicate as well as nanoparticles.

Abstract: A method for the removal of nitrous oxide from off gas by direct decomposition or by selective catalytic reduction in presence of a reducing agent, comprising the steps of contacting the gas directly or together with the reducing agent or a precursor thereof with a catalyst comprising an Fe-AEI zeolite material essentially free of alkali metal ions (Alk) and having the following molar compositions: SiO2: oAl2O3: pFe: qAlk wherein o is in the range from 0.001 to 0.2; wherein p is in the range from 0.001 to 0.2; wherein Alk is one or more of alkali ions and wherein q is less than 0.02.

Abstract: A cold start catalyst is disclosed. The cold start catalyst is effective to adsorb NOx and hydrocarbons (HC) at or below a low temperature and to covert and release the adsorbed NOx and HC at temperatures above the low temperature. The cold start catalyst comprises a molecular sieve catalyst and a supported platinum group metal catalyst. The molecular sieve catalyst consists essentially of a noble metal and a molecular sieve. The supported platinum group metal catalyst comprises one or more platinum group metals and one or more inorganic oxide carriers. The invention also includes an exhaust system comprising the cold start catalyst, and a method for treating exhaust gas from an internal combustion engine utilizing the cold start catalyst.

Abstract: The invention relates to a three-way catalytic converter, which is suitable, in particular, for the removal of carbon monoxide, hydrocarbons and nitrogen oxides out of the exhaust gas of combustion engines operated with stoichiometric air-fuel mixture. The three-way catalytic converter is characterized in that it has a high oxygen storage capacity after aging and consists of at least two catalytically active layers.

Abstract: An oxidation catalyst for treating an exhaust gas from a diesel engine comprises: a first washcoat region for oxidising carbon monoxide (CO) and hydrocarbons (HCs), wherein the first washcoat region comprises a first platinum group metal (PGM) and a first support material, and wherein the first washcoat region does not comprise manganese or an oxide thereof; a second washcoat region for oxidising nitric oxide (NO), wherein the second washcoat region comprises platinum (Pt), manganese (Mn) and a second support material comprising a refractory metal oxide, which is silica-alumina or alumina doped with silica in a total amount of 0.

Abstract: An exhaust gas purification underfloor catalyst characterized in having a catalyst layer having a lower layer and an upper layer, the lower layer containing alumina and CeO2, the noble metal content of the lower layer being at most 0.5 mass % in relation to the mass of the lower layer, the upper layer containing Rh, alumina, and CeO2, the amount of noble metals other than Rh contained being 1 mol % or less in relation to the total amount of noble metals contained in the upper layer, the total amount of CeO2 contained in the lower layer and the upper layer being 14 g/L to 30 g/L, the amount of CeO2 contained in the upper layer being 7 g/L to 25 g/L, and the amount of CeO2 contained in the lower layer being 20% or more of the amount of CeO2 contained in the upper layer.

Abstract: Described are three-way conversion (TWC) catalytic articles effective to abate hydrocarbons (HCs), carbon monoxide (CO), and nitrogen oxides (NOx) from an engine exhaust gas containing phosphorous impurities. The disclosed catalytic article has a layered catalytic material, wherein the first layer of the catalytic material is disposed directly on the substrate and a second layer is disposed on top of the first layer. The second layer includes phosphorus resistant materials that prevent catalytic poisoning of the catalytic article by the phosphorous impurities. In particular, the second layer includes a phosphorus trap material having an alkaline earth metal component and a rhodium component impregnated on a phosphorus-resistant support material.

Abstract: An environmental control system includes an air conditioning subsystem and a contaminant removal subsystem downstream of the environment to be conditioned. The contaminant removal subsystem includes: a first gas-liquid contactor-separator; a second gas-liquid contactor-separator; and a dehumidifier disposed either upstream of the first gas-liquid contactor-separator or downstream of the second gas-liquid contactor-separator.

Abstract: The present invention relates to a catalyst comprising a carrier substrate of the length L extending between substrate ends a and b and two washcoat zones A and B, wherein washcoat zone A comprises a zeolite having a smallest lower channel width of at least 0.4 nm and extends starting from substrate end a over a part of the length L, and washcoat zone B comprises the same components as washcoat A and palladium and extends from substrate end b over a part of the length L, wherein L=LA+LB, wherein LA is the length of washcoat zone A and LB is the length of substrate length B.

Abstract: A NOx adsorber catalyst composition, a NOx adsorber catalyst and its use in an emission treatment system for internal combustion engines, is disclosed. The NOx adsorber catalyst composition a support material and one or more platinum group metals disposed on the support material, wherein the support material comprises a NOx storage enhancer.

Abstract: Catalytic articles comprising a substrate having a catalytic coating thereon, the catalytic coating comprising a catalytic layer having a thickness and an inner surface proximate to the substrate and an outer surface distal to the substrate; where the catalytic layer comprises a noble metal component on support particles and where the concentration of the noble metal component towards the outer surface is greater than the concentration towards the inner surface are highly effective towards treating exhaust gas streams of internal combustion engines. The articles are prepared via a method comprising providing a first mixture comprising micron-scaled support particles and applying the first mixture to a substrate to form a micro-particle layer; providing a second mixture comprising nano-scaled support particles and a noble metal component having an initial pH and applying the second mixture to the micro-particle layer and calcining the substrate.

Abstract: A method of preparing a catalyst composition for producing a stable ratio of NO2 to NO in an exhaust system of a compression ignition engine is described. The method comprises: (i) preparing a first composition comprising a platinum (Pt) compound disposed or supported on a support material; (ii) preparing a second composition by reducing the platinum (Pt) compound to platinum (Pt) with a reducing agent; and (iii) heating the second composition to at least 650° C.

Abstract: An exhaust gas treatment system for an internal combustion engine includes an exhaust gas pathway configured to receive exhaust from the engine, a diesel particulate filter (DPF) element positioned in the exhaust gas pathway to capture particulate matter from the exhaust, and a regenerator operable to increase a temperature of the exhaust that passes through the DPF element. The system also includes a controller configured to selectively operate the exhaust gas treatment system in a first mode in which the regenerator is inactive such that a temperature of the exhaust is within a first range, a second mode in which the regenerator is activated to increase the temperature of the exhaust to a first target temperature beyond the first range, and a third mode in which the regenerator is activated to increase the temperature of the exhaust to a second target temperature greater than the first temperature.

Abstract: An exhaust treatment system is provided, which comprises: a first oxidation catalyst, to oxidize compounds comprising one or more of nitrogen, carbon, and hydrogen; a first dosage device to supply a first additive into an exhaust stream; a catalytic filter, consisting of a particulate filter with an at least partly catalytic coating with reduction characteristics, for catching and oxidizing soot particles and for a first reduction of an amount of nitrogen oxides in the exhaust stream using the first additive; a second oxidation catalyst, to oxidize one or more of nitrogen oxide and incompletely oxidized carbon compounds in the exhaust stream; a second dosage device to supply a second additive into the exhaust stream; and a reduction catalyst device, arranged for a second reduction of nitrogen oxides in the exhaust stream using at least one of the first or second additives.

Abstract: Supported oxidative coupling of methane (OCM) catalysts, methods of making the catalysts, and uses thereof are described. A supported OCM) catalyst can include a nonporous inert support having a high thermal conductivity and an OCM mixed metal oxide material in contact with surface of the nonporous inert support.

Abstract: The present invention relates to a particle filter which comprises a wall-flow filter and SCR-catalytically active material, wherein the wall-flow filter comprises ducts which extend in parallel between a first and a second end of the wall-flow filter and which are alternately closed off in gas-type fashion either at the first or at the second end and which are separated by porous walls, and wherein the SCR-active material comprises a zeolite which is exchanged with copper and/or iron and which is situated in the form of a coating in the porous walls of the wall-flow filter, characterized in that the SCR-catalytically active coating comprises palladium.

Abstract: The present invention relates to a particulate filter which comprises a wall flow filter of length L and three mutually different catalytically active coatings X, Y and Z, wherein the wall flow filter comprises channels E and A that extend in parallel between a first and a second end of the wall flow filter and are separated by porous walls forming surfaces OE and, respectively, OA, and wherein the channels E are gas-tightly sealed at the second end and the channels A are gas-tightly sealed at the first end, characterized in that the coating X is located in the porous walls, the coating Y is located in the channels E on the surfaces OE and the coating Z is located in the channels A on the surfaces OA.

Abstract: The present disclosure provides a method for operating a three-way catalyst system at high temperatures. The method includes passing a high-temperature exhaust stream exiting an engine over a thermally stable three-way catalyst system including a metal oxide support; two or more catalytically active metals disposed on the support; and a porous metal oxide coating disposed on one or more exposed surfaces of the support. At least one of the catalytically active metals may be platinum (Pt). The method further includes reducing an amount of the nitrogen oxides (NOx), carbon monoxide (CO), and non-methane hydrocarbons (HCs) in an effluent stream exiting the thermally stable three-way catalyst system so that the effluent stream has a combined amount of nitrogen oxides (NOx) and non-methane hydrocarbons (HCs) of less than or equal to about 30 mg/mile and less than or equal to about 0.5 g/mile of carbon monoxide (CO).

Abstract: An alumina having a multimodal particle size distribution wherein at least one of the particle sizes giving local maximum values in the particle size distribution is less than 10 ?m, and wherein the alumina comprises 1 to 5 wt % of at least one of La and Ba.

Abstract: The present invention relates to a SCR catalyst comprising a carrier substrate of the length L, which is a flow-through substrate, and a coating A which comprises a small pore zeolite, copper and palladium.

Abstract: A hydrocarbon and NOx catalyst trap includes a three-way catalyst, and a zeolite layer adjacent to the three-way catalyst and including alumina and silica arranged to form a repeating skeletal frame that defines cavities including active metal active sites for hydrocarbon and NOx trapping such that individual atoms of the active metal are bound to the frame within the cavities via oxygen atoms.

Abstract: An after treatment method for a lean-burn engine is disclosed. The after treatment method is configured to control an after treatment system sequentially equipped with an ammonia production catalyst module, a selective catalytic reduction (SCR) catalyst, and a CO clean-up catalyst (CUC) on an exhaust pipe through which an exhaust gas flows and which is connected to a lean-burn engine. In the after treatment method, a rich air/fuel ratio (AFR) is controlled in multiple phases in response to detecting that conversion to the rich AFR is desired.

Abstract: Disclosed is a honeycomb filter for collecting fine particles that includes a wall portion formed from a base material containing ceria-zirconia composite oxide and an inorganic binder. In a pore diameter distribution in which a pore diameter and a log differential pore volume measured through mercury porosimetry are respectively represented by a horizontal axis and a vertical axis, the wall portion has a peak in a range in which the pore diameter is greater than or equal to 0.01 ?m and less than 1 ?m and a peak in a range in which the pore diameter is greater than or equal to 1 ?m and less than or equal to 50 ?m.

Abstract: A diesel oxidation catalyst composition is provided, the composition including at least one platinum group metal impregnated onto a porous refractory oxide material in particulate form and at least one base metal oxide impregnated onto a porous refractory oxide material in particulate form, wherein the porous refractory oxide material impregnated with at least one platinum group metal and the porous refractory oxide material impregnated with at least one base metal oxide are in the form of a mixture or wherein the at least one platinum group metal and the at least one base metal oxide are impregnated on the same porous refractory oxide material. The diesel oxidation catalyst provides synergistic enhancement of carbon monoxide oxidation as well as relatively unimpaired hydrocarbon oxidation. Methods of making and using the catalyst composition are also provided, as well as emission treatment systems comprising a catalyst article coated with the catalyst composition.

Abstract: Catalyst articles having an ammonia slip catalyst (ASC) comprising a blend of platinum on a support with low ammonia storage and a first SCR catalyst, and a second catalyst, such as a diesel oxidation catalyst, a diesel exotherm catalyst (DEC), a NOx absorber, a selective catalytic reduction/passive NOx adsorber (SCR/PNA), a cold-start catalyst (CSC) or a three-way catalyst (TWC) are disclosed. The catalyst articles can also contain one or two additional SCR catalysts. The catalysts can be present in one of various configurations. The catalytic articles are useful for selective catalytic reduction (SCR) of NOx in exhaust gases and in reducing the amount of ammonia slip. Methods of using the catalytic articles in an SCR process, where the amount of ammonia slip is reduced, are also described.

Abstract: An engine control device is provided, which includes an oxidation catalyst provided in an exhaust passage to oxidize unburned fuel within exhaust gas, a NOx catalyst provided integrally with or downstream of the oxidation catalyst, a PM filter provided in the exhaust passage downstream of the oxidation catalyst to capture fine particulate matter within the exhaust gas, a fuel injector, and a controller. When the particulate matter is accumulated by a given amount, the controller starts a PM filter regeneration control to remove the particulate matter, and after this control is started and when the accumulation amount decreases by a given amount, the controller starts a NOx catalyst regeneration control to switch between a first state in which an air-fuel ratio of the exhaust gas is a stoichiometric air-fuel ratio or less and a second state in which the air-fuel ratio is higher than the stoichiometric air-fuel ratio.

Abstract: Emissions treatment systems of combustion engines are provided, which comprise a platinum-containing catalyst that is degreened during production, which is before exposure to operating conditions of a vehicle having a diesel engine. The platinum-containing catalyst, in the form of a platinum component on a high surface area refractory metal oxide support, exhibits a vibration frequency of about 2085 to about 2105 cm?1 as measured by CO-DRIFTS. Such catalytic material is essentially-free of platinum oxide species found at greater than about 2110 cm?1 as measured by CO-DRIFTS. Such catalysts can provide excellent and consistent conversion of nitrogen oxide (NO) to nitrogen dioxide (NO2).

Abstract: A three-way catalyst article, and its use in an exhaust system for internal combustion engines, is disclosed. The catalyst article for treating exhaust gas comprises: a substrate; and a catalytic region on the substrate; wherein the catalytic region comprises a platinum group metal (PGM) component, an oxide, and a rare earth metal component; wherein the oxide is an inorganic oxide, an oxygen storage component (OSC) material, or a mixture thereof; wherein the rare earth metal component concentration by element on the surface of the oxide per unit specific surface area of the oxide is 1 ?mol/m2 to 20 ?mol/m2.