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 object of the present invention is to provide means for improving the hydrogen generation properties of a hydrogen-producing catalyst. A hydrogen-producing catalyst according to one aspect of the present invention comprises Rh and a composite containing Al, Ce, and Zr. When a ratio of the number of Al atoms to the number of Ce atoms (Al/Ce) in the composite measured by X-ray fluorescence (XRF) analysis is R.sub.1 and a ratio of the number of Al atoms to the number of Ce atoms (Al/Ce) in the composite measured by an X-ray photoelectron spectroscopy (XPS) method is R.sub.2, a value of R.sub.2/R.sub.1 is greater than 2.25 and less than 5.92.

The present invention provides an exhaust gas purification catalyst including a base material 11 and a catalyst layer 20 provided on the base material 11. The catalyst layer 20 includes: a catalyst metal; and a carrying material 21 carrying the catalyst metal. The carrying material 21 includes: an OSC material 22 having an oxygen storage capacity; and a carrier 23 other than the OSC material. The OSC material 22 has a mean particle diameter Dx of 1.5 μm or more which is larger than the mean particle diameter Dy of the carrier 23 other than the OSC material 22.

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 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.

Subject of the invention is an exhaust gas purification system for a gasoline engine, comprising in consecutive order the following devices: a first three-way-catalyst (TWC1), a gasoline particulate filter (GPF) and a second three-way-catalyst (TWC2), wherein the wash coat load (WCL) of the TWC2 is greater than the WCL of the GPF, wherein the WCL is determined in g/l of the volume of the device. The invention also relates to methods in which the system is used and uses of the system.

The presently claimed invention provides an automotive catalyst comprising a platinum group metal selected from palladium, platinum, rhodium and any combination thereof; metal oxide nanoparticles; and a carrier, wherein the platinum group metal and the metal oxide nanoparticles are homogeneously dispersed on the carrier such as alumina component. The metal oxide nanoparticles have a D.sub.90 diameter in the range of 1.0 nm to 50 nm. The presently claimed invention also provides a layered catalytic article comprising catalyst comprising at least one platinum group metal; metal oxide nanoparticles; and a carrier. The presently claimed invention also provides a process for preparing the catalyst and the catalytic article, and a method of treating a gaseous exhaust stream comprising contacting the stream with the catalyst or catalytic article.

The presently claimed invention relates an automotive catalyst system which can be used to selectively reduce carbon monoxide. The system comprises a first close coupled three-way conversion catalytic article in fluid communication with an engine exhaust outlet, a catalytic article located downstream of and in fluid communication with the first close coupled three-way conversion catalytic article, a tail-pipe catalytic article arranged downstream in fluid communication and 1.0 to 10 feet away from the catalytic article at a position selected from before or behind a resonator, before or after a muffler, between the resonator and the muffler, inside the muffler, inside the resonator, and at a tail pipe end.

The presently claimed invention provides a catalytic article and an exhaust gas treatment system. The catalytic article comprises platinum supported on a first support comprising ceria containing metal oxide component; rhodium supported on a second support selected from a refractory alumina component, an oxygen storage component or a combination thereof; and a substrate, wherein said catalytic article is essentially free of palladium. The presently claimed invention also provides a process for preparing the catalytic article and use of the catalytic article and the exhaust gas treatment system for purifying a gaseous exhaust stream comprising hydrocarbons, carbon monoxide, and nitrogen oxide.

The present disclosure is directed to compositions comprising Ce-containing mixed oxides, especially those having a stoichiometry of Ln.sub.yCe.sub.xM.sub.wO.sub.z; where 0.15≤x≤0.5, y≤0.25, w=(1−x−y)≥0.5, and z=(2x+2w+1.5y); M is Zr, Hf, Ti, Sn or Ge or a combination thereof; Ln is Y and/or one or more rare earth metals, exclusive of Ce,
and the uses of these compositions. These compositions are characterized by the even distribution of the Ce in the lattice of the mixed oxide.