Abstract: An exhaust gas purifying catalyst includes: a catalyst particle unit having at least noble metal with a catalytic function, first oxides on which the catalyst noble metal is supported, and second oxides covering the first oxides on which the noble metal is supported. In catalyst powder formed of an aggregate of plural pieces of the catalyst particle units, at least one type of compounds selected from the group consisting of a transition element, an alkali earth metal element, an alkali metal element, and a rare earth element, which is a promoter component, are contained.

Abstract: Provided is a method for making a supported metal catalyst. The method includes forming a mixture comprising a high surface area support, a reducing agent precursor that decomposes to produce reducing gases below about 1200° C., and a metal catalyst precursor. The mixture is heated to a temperature sufficient to decompose the reducing agent precursor to produce a reducing agent, and then cooled to form the supported metal catalyst.

Abstract: A catalyst composition is provided comprising a homogeneous solid mixture having ordered directionally aligned tubular meso-channel pores having an average diameter in a range of about 1 nanometer to about 15 nanometers, wherein the homogeneous solid mixture is prepared from a gel formed in the presence of a solvent, modifier, an inorganic salt precursor of a catalytic metal, an inorganic precursor of a metal inorganic network, and a templating agent. The templating agent comprises an octylphenol ethoxylate having a structure [I]: wherein “n” is an integer having a value of about 8 to 20.

Abstract: Ammonia oxidation catalyst being superior in heat resistance and capable of suppressing by-production of N2O and leakage of ammonia. The ammonia oxidation catalyst (AMOX) removes surplus ammonia, in selectively reducing nitrogen oxides by adding urea or ammonia and using a selective catalytic reduction (SCR) catalyst, into exhaust gas, wherein the ammonia oxidation catalyst is made by coating at least two catalyst layers having a catalyst layer (lower layer) including a catalyst supported a noble metal element on a composite oxide (A) having titania and silica as main components, and a catalyst layer (upper layer) including a composite oxide (C) consisting of tungsten oxide, ceria, and zirconia, at the surface of an integral structure-type substrate, wherein a composition of the composite oxide (C) is tungsten oxide: 1 to 50% by weight, ceria: 1 to 60% by weight, and zirconia: 30 to 90% by weight.

Abstract: A method of forming a catalyst, comprising: providing a plurality of support particles and a plurality of mobility-inhibiting particles, wherein each support particle in the plurality of support particles is bonded with its own catalytic particle; and bonding the plurality of mobility-inhibiting particles to the plurality of support particles, wherein each support particle is separated from every other support particle in the plurality of support particles by at least one of the mobility-inhibiting particles, and wherein the mobility-inhibiting particles are configured to prevent the catalytic particles from moving from one support particle to another support particle.

Abstract: The present invention relates to a catalyst comprising a ceramic support with a BET surface area of less than 40 m2/g and (a) 1.0 to 100 g of at least one metal of groups 8 to 12 of the periodic table of the elements, (b) 1.0 g to 100 g of at least one metal of groups 4 to 6 and 12 of the periodic table of the elements and (c) 1.0 g to 100 g of at least one metal of groups 14 and 15 of the periodic table of the elements per litre of bulk volume of the ceramic support, wherein the catalyst is additionally doped with (d) potassium in a content of from 0.0050% by weight to 0.20% by weight, based on the total weight of the catalyst. The present invention also provides the use of such a catalyst in the catalytic gas phase hydrogenation of nitroaromatics.

Abstract: Provided are a method of preparing an electrocatalyst for fuel cells in a core-shell structure, an electrocatalyst for fuel cells having a core-shell structure, and a fuel cell including the electrocatalyst for fuel cells. The method may be useful in forming a core and a shell layer without performing a subsequent process such as chemical treatment or heat treatment and forming a core support in which core particles having a nanosize diameter are homogeneously supported, followed by selectively forming shell layers on surfaces of the core particles in the support. Also, the electrocatalyst for fuel cells has a high catalyst-supporting amount and excellent catalyst activity and electrochemical property.

Abstract: The invention relates to a method for producing a catalyst, wherein the catalyst has a high activity and selectivity with regard to the oxidation of CO and NO. The invention also relates to the catalyst produced using the method according to the invention, the use of the catalyst as oxidation catalyst as well as a catalyst component which contains the catalyst according to the invention. Finally, the invention is directed towards an exhaust-gas cleaning system which comprises the catalyst component containing the catalyst according to the invention.

Abstract: Described is a catalyzed soot filter wherein the inlet coating of the filter comprises an oxidation catalyst comprising platinum (Pt) and optionally palladium (Pd), wherein the outlet coating of the filter comprises an oxidation catalyst comprising Pd and optionally Pt, wherein the Pt concentration in the outlet coating is lower than the Pt concentration in the inlet coating and wherein the weight ratio of Pt:Pd in the outlet coating is in the range of from 0:1 to 2:1; and wherein the inlet coating and the outlet coating are present on the wall flow substrate at a coating loading ratio in the range of from 0.5 to 1.5, calculated as ratio of the loading of the inlet coating (in g/inch3 (g/(2.54 cm)3)):loading of the outlet coating (in g/inch3 (g/(2.54 cm)3)). Systems include such catalyzed soot filters, methods of diesel engine exhaust gas treatment and methods of manufacturing catalyzed soot filters are also described.

Abstract: This invention relates to a metal catalyst, a manufacturing method of the metal catalyst, and an electrochemical reduction method. The metal catalyst is manufactured by a method comprising providing a conductor to one side of an insulator, providing a fluid including a metal ion and an electron mediator to the other side of the insulator and providing a voltage to the conductor. The electrochemical reduction method comprises providing a conductor to one side of an insulator, providing a fluid including reduction material and an electron mediator to the other side of the insulator and providing a voltage to the conductor.

Abstract: Disclosed is a lean NOx trap (LNT) catalyst with enhanced NOx storage capacity at low temperature. More particularly, an LNT catalyst with enhanced NOx storage capacity at low temperature and significantly inhibited thermal desorption is prepared by coating a washcoat on a honeycomb-type carrier and drying and baking the same. The washcoat contains a first catalyst powder in which barium (Ba) and a precious metal are supported on a ceria support, and a second catalyst powder in which a precious metal is supported on a magnesium (Mg)-substituted alumina support The LNT catalyst of the present invention is useful as a NOx reducing catalyst for a passenger diesel vehicle.

Abstract: Disclosed is an exhaust gas purifying catalyst in which grain growth of a noble metal particle supported on a support is suppressed. Also, disclosed is a production process of an exhaust gas purifying catalyst, by which the above exhaust gas purifying catalyst can be produced. The exhaust gas purifying catalyst comprises a crystalline metal oxide support and a noble metal particle supported on the support, wherein the noble metal particle is epitaxially grown on the support, and wherein the noble metal particle is dispersed and supported on the outer and inner surfaces of the support. The process for producing an exhaust gas purifying catalyst comprises masking, in a solution, at least a part of the surface of a crystalline metal oxide support by a masking agent, introducing the support into a noble metal-containing solution containing a noble metal, and drying and firing the support and the noble metal-containing solution to support the noble metal on the support.

Abstract: An exhaust gas purification catalyst has a substrate, a lower catalyst layer that is formed on the substrate and contains at least one of Pd and Pt, and an upper catalyst layer that is formed on the lower catalyst layer and contains Rh. A region that does not contain the upper catalyst layer is disposed on the exhaust gas upstream side of this exhaust gas purification catalyst. The lower catalyst layer includes a front-stage lower catalyst layer on the exhaust gas upstream side and a rear-stage lower catalyst layer on the exhaust gas downstream side. The front-stage lower catalyst layer contains an oxygen storage material.

Abstract: A self-assembly platinum nanostructure with a three dimensional network structure contains a plurality of platinum nanoparticles having a cubic shape, wherein the plurality of platinum nanoparticles gather to form a cubic shape and are disposed in a {111} direction.

Abstract: A platinum-rhodium nano-dendritic alloy includes a plurality of first structure having a round shape and a second structure connecting the plurality of first structures and having a thin bridge shape, wherein the first and second structures containing platinum and rhodium homogeneously distributed therein.

Abstract: A process for preparing a slurry catalyst is provided. The slurry catalyst is prepared from at least a Group VIB metal precursor and optionally at least a Promoter metal precursor selected from Group VIII, Group IIB, Group IIA, Group IVA metals and combinations thereof. The slurry catalyst comprises a plurality of dispersed particles in a hydrocarbon medium having an average particle size ranging from 1 to 300 ?m. The slurry catalyst is then mixed with a hydrogen feed at a pressure from 1435 psig (10 MPa) to 3610 psig (25 MPa) and a temperature from 200-800° F. at 500 to 15,000 scf hydrogen per bbl of slurry catalyst for a minute to 20 hours, for the slurry catalyst to be saturated with hydrogen providing an increase of k-values in terms of HDS, HDN, and HDMCR of at least 15% compared to a slurry catalyst that is not saturated with hydrogen.

Abstract: A catalyst comprising: a platinum group metal, silver, gold, or a mixture thereof, and a carrier containing an oxide other than zirconium oxide and a precipitate layer of zirconium oxide onto the oxide other than zirconium oxide, as well as their uses in production of hydrogen peroxide. A process for producing hydrogen peroxide, comprising reacting hydrogen and oxygen in the presence of such catalyst in a reactor, and a process for producing such catalyst.

Abstract: Provided herein are catalytic articles and methods of making same using a single coat process. The catalytic article comprises an elongated substrate monolith having a plurality of longitudinally extending passages, each passage having at least a first surface and a second surface opposite the first surface, the first and second surfaces coated with at least a first coating and a second coating, wherein the first coating comprises a first catalyst composition and overlies the second coating on the first surface, the second coating comprises a second catalyst composition and overlies the first coating on the second surface, and wherein the first catalyst composition and second catalyst composition have a difference in surface charge. The washcoat may be applied as one slurry, which then self-segregates into two coatings.

Abstract: An oxidation catalyst composite, methods, and systems for the treatment of exhaust gas emissions from a diesel engine are described. More particularly, an oxidation catalyst composite including a zoned diesel oxidation catalyst with a first washcoat zone with a Pt/Pd ratio that is less than 3:1 and a PGM loading at least twice that of a second washcoat zone.

Abstract: There is presented a catalyst support that has a substantially spherical body, penetrated with a plurality of tunnels extending from a first end on a surface location of the catalyst body to another end on another surface location of the body. The support is made of alumina or like composition. The catalyst body has a total surface that includes the outer surface and surfaces within the tunnels. This total surface is adapted to receive catalyst composition. The catalyst support is adapted to being packed in a reactor and provides lower packed bed pressure drop.

Abstract: A catalyst comprising: a platinum group metal, silver or gold, and a carrier containing niobium or tantalum oxide or niobium or tantalum phosphate, and an oxide other than niobium or tantalum oxide, as well as its use in production of hydrogen peroxide. A process for producing hydrogen peroxide, comprising reacting hydrogen and oxygen in the presence of such catalyst in a reactor, and a process for producing such catalyst.

Abstract: Catalyst articles comprising substantially only a palladium precious metal component in a first catalytic layer and a rhodium component in a second catalytic layer and related methods of preparation and use are disclosed. Also disclosed is a catalyst article comprising a first layer formed on a carrier substrate, wherein the first layer comprises a refractory metal oxide and has a surface that is substantially uniform; a second layer formed on the first layer, wherein the second layer comprises i) an oxygen storage component that is about 50-90% by weight of the second layer and ii) a palladium component in an amount of about 2-5% by weight of the second layer, wherein the palladium component is substantially the only platinum group metal component, and a palladium-free third layer comprising a rhodium component supported on a thermostable oxygen storage component which is about 80-99% by weight of the second layer. One or more improved properties are exhibited by the catalyst article.

Abstract: A method for making hollow metal tubes includes a step combining a polyphenylene sulfide-containing resin with a water soluble carrier resin to form a resinous mixture. The resinous mixture is then extruded to form an extruded resinous mixture. The extruded resinous mixture includes polyphenylene sulfide-containing fibers within the carrier resin. The extruded resinous mixture is contacted (i.e., washed) with water to separate the polyphenylene sulfide-containing fibers from the carrier resin. The polyphenylene sulfide-containing fibers are then coated with a metal layer. The hollow metal tubes are then formed by removing the polyphenylene sulfide-containing fibers.

Abstract: There is provided a catalyst comprising metal nanoparticles supported on nanocrystalline cellulose and a homogeneous catalyst system comprising this catalyst colloidally suspended in a fluid. There is also provided a method of producing this catalyst and various uses thereof.

Abstract: An exhaust purifying catalyst includes: a substrate; a first-stage catalyst that includes an oxygen storage capacity (OSC) material and that is provided on the substrate on an upstream side thereof in an exhaust gas flow direction; and a second-stage catalyst that includes an OSC material and that is provided on the substrate on a downstream side thereof in an exhaust gas flow direction. The OSC material included in the first-stage catalyst and the second-stage catalyst includes OSC material on which a noble metal is not supported. The proportion of the amount of the OSC material, on which a noble metal is not supported, and that is included in the second-stage catalyst with respect to the combined amount of the OSC material, on which a noble metal is not supported, and that is included in the first-stage catalyst and the second-stage catalyst is in a range of from 0 to 50 wt %.

Abstract: A metal oxide nanorod array structure according to embodiments disclosed herein includes a monolithic substrate having a surface and multiple channels, an interface layer bonded to the surface of the substrate, and a metal oxide nanorod array coupled to the substrate surface via the interface layer. The metal oxide can include ceria, zinc oxide, tin oxide, alumina, zirconia, cobalt oxide, and gallium oxide. The substrate can include a glass substrate, a plastic substrate, a silicon substrate, a ceramic monolith, and a stainless steel monolith. The ceramic can include cordierite, alumina, tin oxide, and titania. The nanorod array structure can include a perovskite shell, such as a lanthanum-based transition metal oxide, or a metal oxide shell, such as ceria, zinc oxide, tin oxide, alumina, zirconia, cobalt oxide, and gallium oxide, or a coating of metal particles, such as platinum, gold, palladium, rhodium, and ruthenium, over each metal oxide nanorod.

Abstract: The exhaust gas purification catalyst according to the present invention has a substrate 54, a lower layer 57 disposed on this substrate 54, and an upper layer 58 disposed on this lower layer 57. The upper layer 58 is provided with a first catalyst and a second catalyst, and the lower layer 57 is provided with a first catalyst. This first catalyst has Al2O3 as a carrier and Pt and Pd as noble metals supported on the Al2O3, while the second catalyst typically has an Al2O3—ZrO2—TiO2 complex oxide as a carrier and has Pd as a noble metal supported on the Al2O3—ZrO2—TiO2 complex oxide. Moreover, the upper layer 58 has a hydrocarbon adsorbent 68.

Abstract: Catalyst articles comprising palladium and related methods of preparation and use are disclosed. Disclosed is a catalyst article comprising a first catalytic layer formed on a substrate, wherein the first catalytic layer comprises palladium impregnated on a ceria-free oxygen storage component and platinum impregnated on a refractory metal oxide, and a second catalytic layer formed on the first catalytic layer comprising platinum and rhodium impregnated on a ceria-containing oxygen storage component. The palladium component of the catalyst article is present in a higher proportion relative to the other platinum group metal components. The catalyst articles provide improved conversion of carbon monoxide in exhaust gases, particularly under rich engine operating conditions.

Abstract: Aspects of the invention relate to hydrogenation catalysts, and hydrogenation processes using these catalysts, having particular characteristics, in terms of the amount and type of metal hydrogenation component (or catalytic constituent), as well as the support or substrate. The catalyst compositions, comprising both a noble metal and a lanthanide element on a substantially non-porous substrate, provide advantageous performance characteristics, including conversion, selectivity, and activity stability, as demanded in industrial hydrogenation and selective hydrogenation applications.

Abstract: An oxidation catalyst for treating an exhaust gas produced by a combustion engine, wherein the oxidation catalyst comprises a substrate and a catalyst layer, wherein the catalyst layer comprises: a first support material; a first noble metal; and a second noble metal; wherein the catalyst layer is disposed on a surface of the substrate, and the catalyst layer has a non-uniform distribution of the first noble metal in a direction perpendicular to the surface of the substrate. The oxidation catalyst can be used to oxidise carbon monoxide (CO), hydrocarbons (HCs) and also oxides of nitrogen (NOx) in such an exhaust gas.

Abstract: A process for preparing an improved slurry catalyst for the upgrade of heavy oil feedstock is provided. The process comprises providing at least a metal precursor in solution comprising at least two different metal cations in its molecular structure, with at least one of the metal cations is a Group VIB metal cation; sulfiding the metal precursor with a sulfiding agent in solution forming a catalyst precursor; and mixing the catalyst precursor with a hydrocarbon diluent to form the slurry catalyst. In one embodiment, the at least a metal precursor comprising at least two different metal cations is prepared by combining and reacting at least one Group VIB metal compound with at least a Promoter metal compound selected from Group VIII, Group IIB, Group IIA, Group IVA metals and combinations thereof.

Abstract: An improved process for preparing a slurry catalyst for the upgrade of heavy oil feedstock is provided. In the process, high shear mixing is employed to generate an emulsion containing droplets of metal precursor in oil with droplet sizes ranging from 0.1 to 300 ?m. The emulsion is subsequently sulfided with a sulfiding agent, or in-situ in a heavy oil feedstock to form a slurry catalyst. The in-situ sulfidation in heavy oil is under sufficient condition for the heavy oil feedstock to generate the sulfiding source needed for the sulfidation.

Abstract: Provided is a structure for forming carbon nanofiber, including a base material containing an oxygen ion-conductive oxide, and a metal catalyst that is provided on one surface side of the base material.

Abstract: A catalyst comprising at least one catalytically active metal selected from the group consisting of elements of Groups 7 to 11, wherein the catalytically active metal is supported on a support material being grafted with acid groups other than OH groups, wherein a metal is in the bulk of the support material, and wherein the catalytically active metal is different from the metal of the support material. A method for preparing such catalyst and the use of such catalyst for catalyzing reactions.

Abstract: An improved process to make a slurry catalyst for the upgrade of heavy oil feedstock is provided. The sulfiding of the metal precursor/catalyst precursor is carried out at least twice (“enhanced sulfiding”) in the improved process to form a slurry catalyst with improved surface area and porosity value. The slurry catalyst under an enhanced sulfiding scheme is characterized as having increased catalytic activities over a slurry catalyst without an enhanced sulfidation step.

Abstract: The invention relates to a filtration structure, for filtering a gas coming from a diesel engine, which is laden with gaseous pollutants of the nitrogen oxide NOx type and with solid particles, of the particulate filter type, said filtration structure being characterized in that it includes a catalytic system comprising at least one noble metal or transition metal suitable for reducing the NOx and a support material, in which said support material comprises or is made of a zirconium oxide partially substituted with a trivalent cation M3+ or with a divalent cation M?2+, said zirconium oxide being in a reduced, oxygen-sub-stoichiometric, state.

Abstract: An improved hydroprocessing slurry catalyst is provided for the upgrade of heavy oil feedstock. The catalyst comprises dispersed particles in a hydrocarbon medium with the dispersed particles have an average particle size ranging from 1 to 300 ?m. The catalyst has a total pore volume of at least 0.5 cc/g and a polymodal pore distribution with at least 80% of pore sizes in the range of 5 to 2,000 Angstroms in diameter. The catalyst is prepared from sulfiding and dispersing a metal precursor solution in a hydrocarbon diluent, the metal precursor comprising at least a Primary metal precursor and optionally a Promoter metal precursor, the metal precursor solution having a pH of at least 4 and a concentration of less than 10 wt. % of Primary metal in solution.

Abstract: Novel methods of electroless plating are described. Catalyst coatings can be applied within microchannel apparatus. Various reactions, including combustion and steam reforming, can be conducted over electroless catalyst coatings.

Abstract: A catalyst for purification of exhaust gas, in which a noble metal is supported on a metal oxide support, has a basic site content of 1 mmol/L-cat or less, as determined on the basis of an amount of CO2 desorbed per liter of the catalyst as measured by a CO2 temperature-programmed desorption method.

Abstract: An exhaust gas purification catalyst is provided with a catalyst coating layer (40) formed on the surface of a substrate (32). This catalyst coating layer (40) is formed of an upper catalyst coating layer (36) in which Rh particles are supported on a porous support, and a lower catalyst coating layer (34) in which Pd particles are supported on a support that contains an ACZ composite oxide made of alumina (Al2O3), ceria (CeO2), and zirconia (ZrO2).

Abstract: A layered catalyst including a surface axis including a catalyst material layer, and a substrate material layer contacting the catalyst material layer. The catalyst material layer includes a compressed atomic distance between two adjacent catalyst atoms along the surface axis relative to an atomic distance of the same catalyst material as in bulk. The substrate material has a higher surface energy than the catalyst material. In certain instances, at least 70 percent of total atoms of the catalyst material are in a film growth mode. In certain other instances, a surface free energy of the substrate material is 1 to 50 percent greater than a surface free energy of the catalyst material. In yet certain other instances, the catalyst material layer has a d-band center in a range of ?2.1 eV to ?2.25 eV.

Abstract: The present disclosure provides a catalyst product having particular three-dimensional plate-like shape and comprising catalyst nanoparticles and a method for manufacturing same. The present product may be useful in fuel cells or battery applications. In certain embodiments the present catalysts show good catalytic activity and durability even at low catalyst loads.

Abstract: A composition comprising an extruded inorganic support comprising an oxide of a metal or metalloid, and at least one catalytically active metal, wherein the extruded inorganic support has pores, a total pore volume, and a pore size distribution, wherein the pore size distribution displays at least two peaks of pore diameters, each peak having a maximum, wherein a first peak has a first maximum of pore diameters of equal to or greater than about 120 nm and a second peak has a second maximum of pore diameters of less than about 120 nm, and wherein greater than or equal to about 5% of a total pore volume of the extruded inorganic support is contained within the first peak of pore diameters.

Abstract: A method for producing a catalyst supporting a metal or an alloy on a support, including: independently controlling a temperature of a first supercritical fluid to be first temperature, the first supercritical fluid containing a precursor of the metal or precursor of the alloy that is dissolved in a supercritical fluid; independently controlling a temperature of the support to be a second temperature higher than the temperature of the first supercritical fluid; and supplying the first supercritical fluid controlled to the first temperature to the support, to cause the metal or the alloy to be supported on the support.

Abstract: A platinum alloy catalyst PtXY, wherein X is nickel, cobalt, chromium, copper, titanium or manganese and Y is tantalum or niobium, characterised in that in the alloy the atomic percentage of platinum is 46-75 at %, of X is 1-49 at % and of Y is 1-35 at %; provided that the alloy is not 66 at % Pt 20 at % Cr14 at % Ta or 50 at % Pt, 25 at % Co, 25 at % Ta is disclosed. The catalyst has particular use as an oxygen reduction catalyst in fuel cells, and in particular in phosphoric acid fuel cells.

Abstract: The present invention relates to a nitrogen oxide storage catalyst comprising: a substrate; a first washcoat layer disposed on the substrate, the first washcoat layer comprising metal oxide support particles and a nitrogen oxide storage material comprising at least one metal compound selected from the group consisting of alkaline earth metal compounds, alkali metal compounds, rare earth metal compounds, and mixtures thereof, at least a portion of said at least one metal compound being supported on the metal oxide support particles; and a second washcoat layer disposed over the first washcoat layer, said second washcoat layer comprising Rh, wherein the first washcoat layer contains substantially no Rh, and wherein the second washcoat layer is disposed on 100-x % of the surface of the first washcoat layer, x ranging from 20 to 80.

Abstract: The present invention provides core-shell type metal nanoparticles having a high surface coverage of the core portion with the shell portion, and a method for producing the same. Disclosed is core-shell type metal nanoparticles comprising a core portion comprising a core metal material and a shell portion covering the core portion, wherein the core portion substantially has no {100} plane of the core metal material on the surface thereof.

Abstract: The present invention is directed to a catalyst suitable for catalyzing a Fischer-Tropsch reaction, said catalyst comprising cobalt metal supported on zinc-oxide and having the following particle size distribution by volume: <10% having a particle size below 1 micron, 70-99% having a particle size between 1 and 5 micron, and <20% having a particle size above 5 micron.

Abstract: A process for preparing a slurry catalyst for the upgrade of heavy oil feedstock is provided. The process employs a pressure leach solution obtained from a metal recovery process as part of the metal precursor feed. In one embodiment, the process comprises: sulfiding a pressure leach solution having at least a Group VIB metal precursor compound in solution forming a catalyst precursor, and mixing the sulfided catalyst precursor with a hydrocarbon diluent to form the slurry catalyst. In another embodiment, the pressure leach solution is mixed with a hydrocarbon diluent under high shear mixing conditions to form an emulsion, which emulsion can be sulfided in-situ upon contact with a heavy oil feedstock in the heavy oil upgrade process.

Abstract: The present invention relates to metal oxide particles having cores comprising larger molar amounts of zirconia than of ceria, and surface layers comprising larger molar amounts of ceria than of zirconia. Further, the present invention relates to a method for preparing the particles. The method comprises preparing a solution comprising zirconia sol and ceria sol, adjusting the pH of the solution within ±0.5 on the basis of the isoelectric point of zirconia, and aggregating zirconia and then aggregating ceria around the aggregated zirconia from the solution to make aggregates. Furthermore, the present invention relates to an exhaust gas purifying catalyst comprising the metal oxide particles, and a noble metal carried by the metal oxide particles.