The object of the present invention is to provide an exhaust gas purifying catalyst that can achieve high purification performance while suppressing H.sub.2S emissions. The object is solved by an exhaust gas purifying catalyst in which the top layer of a catalyst coating layer comprises a ceria-zirconia composite oxide having a pyrochlore-type ordered array structure, in which the ceria-zirconia composite oxide contains at least one additional element selected from the group consisting of praseodymium, lanthanum, and yttrium at 0.5 to 5.0 mol % in relation to the total cation amount, and the molar ratio of (cerium+additional element):(zirconium) is within the range from 43:57 to 48:52.

An exhaust gas cleaning catalyst that has: a substrate having a wall flow structure, wherein an entry side cell, in which the end part on an exhaust gas inflow side is open, and an exit side cell, in which the end part on the exhaust gas outflow side is open, are divided by a porous dividing wall; and a first catalyst layer that includes a metal catalyst and is disposed within the dividing wall so as to be in contact with the exit side cell and not in contact with the entry side cell, and no catalyst layer is provided in the region in contact with the entry side cell.

The invention relates to a wall flow filter for removing particulate matter from the exhaust of internal combustion engines, comprising a wall flow filter substrate having a length L, and different coatings Z and F, the wall flow filter substrate being provided with channels E and A which run parallel between a first end and a second end of the wall flow filter substrate, are separated by porous walls, and form surfaces O.sub.E and O.sub.A, respectively; channels E are closed at the second end, and channels A are closed at the first end; coating Z is disposed in the porous walls and/or on surfaces O.sub.A, but not on surfaces O.sub.E, and contains palladium and/or rhodium and a cerium/zirconium mixed oxide; coating F is disposed mainly on surfaces O.sub.E, but not on surfaces O.sub.A, and comprises a membrane and no precious metal. The wall flow filter is characterized in that the mass ratio of coating Z to coating F ranges from 0.1 to 25.

The present invention relates to a wall flow filter for removing particles from the exhaust gas of internal combustion engines, which comprises a wall flow filter substrate having a length L and coatings Z and F that differ from one another, wherein the wall flow filter substrate comprises channels E and A, which extend in parallel between a first and a second end of the wall flow filter substrate, are separated by porous walls and form surfaces OE or OA, and wherein the channels E are closed at the second end and the channels A are closed at the first end, and wherein the coating Z is located in the porous walls and/or on the surfaces OA, but not on the surfaces OE, and comprises palladium and/or rhodium a cerium/zirconium mixed oxide, characterized in that the coating F is located in the porous walls and/or on the surfaces OE, but not on the surfaces O, and comprises a ceramic membrane and no precious metal.

A method for the manufacture of a Gasoline Particulate Filter is disclosed. The method comprises forming a washcoat slurry, coating a wall-flow filter substrate with the washcoat slurry to form a washcoated substrate, and calcining the washcoated substrate to form a Gasoline Particulate Filter. The washcoat slurry comprises a platinum group metal component consisting of Pt and Rh, an oxygen storage capacity material, and a carboxylate ion.

The present invention provides a catalyst composition comprising at least one platinum group metal; and at least one complex metal oxide wherein the at least one platinum group metal is supported on the at least complex metal oxide, wherein the complex metal oxide comprises ceria (calculated as CeO.sub.2) in an amount of about 50 to about 99 wt. %, based on the total weight of the complex metal oxide; and zirconia (calculated as ZrO.sub.2) in an amount of about 1.0 to about 50 wt. %, based on the total weight the complex metal oxide. The present invention also provides a catalytic article made from said catalyst composition, its preparation and use for the treatment of the exhaust gases.

This disclosure is directed to catalyst compositions, catalytic articles for purifying exhaust gas emissions and methods of making and using the same. In particular, the disclosure relates to a catalytic article including a catalytic material on a substrate, wherein the catalytic material has a first layer and a second layer. The first layer provides effective lean NO.sub.x trap functionality and the second layer provides effective three-way conversion of carbon monoxide, hydrocarbons, and nitrogen oxides (NO.sub.x).

The present disclosure provides an exhaust gas purification catalyst with increased exhaust gas purification performance. The exhaust gas purification catalyst has a porous support, catalyst metal particles supported in the pores of the porous support, and zirconium dioxide particles supported in the pores of the porous support. The zirconium dioxide particles are supported in a uniformly dispersed manner in the pores, as monoclinic crystals or a mixture of monoclinic crystals and tetragonal crystals, the phrase supported in a uniformly dispersed manner meaning that when the exhaust gas purification catalyst is measured with an electron beam microanalyzer, the proportion of the abundance ratio of zirconium in a surface region up to a depth of 1.5 m from the exhaust gas purification catalyst surface with respect to the abundance ratio of zirconium in the region inward from that surface region of the exhaust gas purification catalyst, is 95 to 105 mol %.

The present invention provides an ohmic heating-type exhaust gas purification catalyst system. The ohmic heating-type exhaust gas purification catalyst system is configured to perform, based on information of temperature of a catalyst bed input from a temperature detector of an ohmic heating-type exhaust gas purification device, electric current pass control including controls of (1) causing an electric current to pass through a pair of electrodes when the temperature of the catalyst bed is equal to or lower than a first threshold temperature T1 set in a range of 350?25? C., (2) not causing an electric current to pass through the pair of electrodes when the temperature of the catalyst bed exceeds the first threshold temperature T1 and is equal to or lower than a second threshold temperature T2 set in a range of 450?25? C., (3) causing an electric current caused to pass through the pair of electrodes when the temperature of the catalyst bed exceeds the second threshold temperature T2 and is equal to or lower than a third threshold temperature T3 set to be equal to or higher than 550? C., and (4) not causing an electric current to pass through the pair of electrodes when the temperature of the catalyst bed exceeds the third threshold temperature T3.

A Pd-supporting Zr-based composite oxide wherein by having a Zr-containing composite oxide support and Pd supported thereon and by showing, upon XAFS (X-ray absorption fine structure) analysis, a maximum peak in a Pd bond distance range of 2.500-3.500 , the maximum peak being located in a position of 3.050-3.110 .