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, an outlet end with an axial length L; a first catalytic region beginning at the inlet end and extending for less than the axial length L, wherein the first catalytic region comprises a first palladium component; a second catalytic region beginning at the outlet end and extending for less than the axial length L, wherein the second catalytic region comprises a second palladium component; a third catalytic region beginning at the outlet end and extending for less than the axial length L, wherein the third catalytic region comprises a third rhodium component; and wherein the third catalytic region overlies the second catalytic region.

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, an outlet end with an axial length L; a first catalytic region beginning at the inlet end and extending for less than the axial length L, wherein the first catalytic region comprises a first palladium component; a second catalytic region beginning at the outlet end and extending for less than the axial length L, wherein the second catalytic region comprises a second palladium component; a third catalytic region beginning at the outlet end and extending for less than the axial length L, wherein the third catalytic region comprises a third rhodium component; and wherein the third catalytic region overlies the second catalytic region.

An exhaust gas cleaning catalyst is provided with a fire-resistant three-dimensional structural body, a first catalyst layer provide on a first surface side of the fire-resistant three-dimensional structural body, and a second catalyst layer provided on a side of the first catalyst layer opposite to the fire-resistant three-dimensional structural body. The first catalyst layer contains: a complex oxide including cerium and zirconium; and elemental rhodium. The second catalyst layer contains: a complex oxide including cerium and zirconium; and elemental palladium. The amount of cerium included in the second catalyst layer, in terms of cerium dioxide, is 10-25 g per liter of the fire-resistant three-dimensional structural body.

A novel alloy nanoparticle which the alloy nanoparticle contains five or more types of elements, in the case where the alloy nanoparticle is directly supported on a carbon material carrier, the carbon material carrier excludes graphene or carbon fibers; an aggregate of alloy nanoparticles; a catalyst; a production method for alloy nanoparticles.

A hydrocarbon reforming catalyst that is used in production of a synthesis gas containing hydrogen and carbon monoxide from a hydrocarbon-based gas includes a composite oxide having a perovskite structure, wherein the composite oxide has at least one crystal phase among a first crystal phase containing BaZrO.sub.3 as a main component and a second crystal phase containing BaCeO.sub.3 as a main component, and contains Rh.

A four-way conversion catalyst for treating a gasoline engine exhaust gas has a porous wall flow filter substrate with an inlet end, outlet end, substrate axial length extending between the inlet and outlet end, and passages defined by porous internal walls of the substrate, the passages having inlet passages with an open inlet and closed outlet, and outlet passages having a closed inlet and open outlet. The internal wall pores have a three-way conversion catalytic in-wall coating with an oxygen storage compound and a platinum group metal supported on a refractory metal oxide. On at least a portion of the internal wall surface defining the interface between the internal walls and the passages, the catalyst has a porous on-wall coating from the internal wall surface to the passage. The coating has porous oxidic compound and platinum group metal content of 0 to 0.001 wt. %, of the total coating weight.

A four-way conversion catalyst for treating a gasoline engine exhaust gas has a porous wall flow filter substrate with an inlet end, outlet end, substrate axial length extending between the inlet and outlet end, and passages defined by porous internal walls of the substrate, the passages having inlet passages with an open inlet and closed outlet, and outlet passages having a closed inlet and open outlet. The internal wall pores have a three-way conversion catalytic in-wall coating with an oxygen storage compound and a platinum group metal supported on a refractory metal oxide. On at least a portion of the internal wall surface defining the interface between the internal walls and the passages, the catalyst has a porous on-wall coating from the internal wall surface to the passage. The coating has porous oxidic compound and platinum group metal content of 0 to 0.001 wt. %, of the total coating weight.

A carrier for an ethylene epoxidation catalyst, the carrier comprising a porous alumina body formed of sintered particles of alumina in a substantial absence of inorganic binder species other than alumina, wherein the substantial absence of inorganic binder species corresponds to an amount of less than 0.6 wt % inorganic binder species other than alumina and comprises at least a substantial absence of silicon-containing species.

A carrier for an ethylene epoxidation catalyst, the carrier comprising a porous alumina body formed of sintered particles of alumina in a substantial absence of inorganic binder species other than alumina, wherein the substantial absence of inorganic binder species corresponds to an amount of less than 0.6 wt % inorganic binder species other than alumina and comprises at least a substantial absence of silicon-containing species.

Provided is, for example, an exhaust gas-purifying three-way catalyst which is small in the amount of a platinum group element used, which can be early increased in temperature to a catalytically active temperature, which is suppressed in degradation in performance due to a catalyst poison included in an exhaust gas even if placed directly under an engine, and which is excellent in purification performance. An exhaust gas-purifying three-way catalyst including at least a catalyst carrier 11 and a catalyst layer 21, wherein the catalyst layer 21 has a layered structure having at least a first catalyst layer L1, a second catalyst layer L2 and a third catalyst layer L3 in the listed order, the first catalyst layer L1 contains a first composite catalyst particle including palladium supported on a first base material particle, the second catalyst layer L2 contains a second composite catalyst particle including rhodium supported on a second base material particle, the third catalyst layer L3 contains a third composite catalyst particle including palladium supported on a third base material particle, and the total coating weight Wt in the catalyst layers L1, L2, and L3 (provided that the platinum group element included in each of the catalyst layers is excluded) is 110 g/L or more and 225 g/L or less in total, per volume of the catalyst carrier 11.