The present disclosure provides the exhaust gas purification catalyst capable of efficiently converting HC in the upstream region relative to the exhaust gas flow direction in the exhaust gas purification catalyst and capable of efficiently converting NOx in the downstream region relative to the exhaust gas flow direction in the exhaust gas purification catalyst while maintaining the good warming-up performance. The present disclosure relates to an exhaust gas purification catalyst including a monolith substrate formed by a catalyst carrier and a catalyst coat layer coated on the monolith substrate, in which the monolith substrate contains Pd, the catalyst coat layer includes a downstream coat layer, the downstream coat layer contains Rh, a density of the downstream coat layer is in a specific range, the exhaust gas purification catalyst has an upstream region (upstream portion) relative to an exhaust gas flow direction and a downstream region (downstream portion) excluding the upstream region and the upstream portion has a Pd concentration higher than a Pd concentration in the downstream portion.

The present disclosure is directed to compositions for use in oxygen capture applications, for example in three-way catalysts (TWC) systems. In some embodiments, the compositions comprise composites of aggregated and/or fused primary particles, the aggregated and/or fused primary particles collectively having the formulae [MnO.sub.x].sub.y:[La.sub.zMnO.sub.3].sub.1y; wherein x is in a range from about 1 to 2.5; y is in a range from about 1 to about 30 wt %, or from about 1 to about 20 wt % or from about 2-10 wt % or from about 2 to about 5 wt %; and z is about 0.7 to about 1.1; and the La.sub.zMnO.sub.3 is a crystalline perovskite phase; the aggregated and/or fused primary particles of the composite having a mean surface area in a range of from about 25 to about 60 m.sup.2/g, preferably from about 27 to about 45 m.sup.2/g. In preferred embodiments, these compositions further comprise low levels of at least one platinum group metal (PGM), preferably Pd.

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.

The present invention provides catalyst article, and its use in an exhaust system for internal combustion engines, is disclosed. The catalyst article catalyst article comprises: a substrate which is a wall-flow filter having an inlet end and an outlet end and an axial length L therebetween, a plurality of inlet channels extending from the inlet end and a plurality of outlet channels extending from the outlet end, wherein the plurality of inlet channels comprise a first catalyst composition extending from the inlet or outlet end for at least 50% of L and the plurality of outlet channels comprise a second catalyst composition extending from the outlet or inlet end for at least 50% of L, wherein the first and second catalyst compositions overlap by at most 80% of L, and wherein the first and second catalyst compositions each independently comprise a particulate oxygen storage component (OSC) having a first D90 and a particulate inorganic oxide having a second D90 and: i) the first D90 is less than 1 micron and the second D90 is from 1 to 20 microns; or ii) the second D90 is less than 1 micron and the first D90 is from 1 to 20 microns.

A process for removing hydrocarbons from a feed stream containing hydrocarbons includes introducing ozone to the feed stream to produce an ozone doped stream containing ozone and hydrocarbons, and contacting the ozone doped stream with a supported metal catalyst at a temperature of from 100 C. to 300 C. to produce a treated stream, wherein the supported metal catalyst comprises iron supported on a support selected from aluminosilicates, silica-aluminas, silicates and aluminas. A process for removing NO.sub.x from a feed stream containing NO.sub.x, and an apparatus for removing hydrocarbons and/or NO.sub.x from a feed stream containing hydrocarbons and/or NO.sub.x are also provided.

Provided is an exhaust gas purification catalyst that allows enhancing purification performance on exhaust gas. The exhaust gas purification catalyst according to the present invention has a substrate 10 of wall flow structure having a porous partition wall 16 which partitions inlet cells 12 and outlet cells 14, a first catalyst layer 20 formed on the surface of the partition wall 16, on the side facing the inlet cells 12, and a second catalyst layer 30 formed in the interior of the partition wall 16, at least in a region facing the outlet cells 14.

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/m.sup.2 to 20 mol/m.sup.2.

An exhaust gas purification including: a base of wall flow structure having inlet side cells wherein an end on the exhaust gas inflow side is open and outlet side cells wherein an end on the exhaust gas outflow side is open, and a porous partition wall that partitions the side cells; and first and second catalyst layers disposed in the interior of the porous partition wall so as to be in contact with the side cells, wherein either of the catalyst layers contains an oxidation catalyst but does not contain a reduction catalyst, and the other contains the reduction catalyst but does not contain the oxidation catalyst; and a ratio of the lengths of the catalyst layers differs between a surface of the porous partition wall on the side in contact with the inlet side cells and a surface on the side in contact with the outlet side cells.

An exhaust gas purifying catalyst according to the present invention is provided with a base material 10 and a catalyst-coated layer 30. The catalyst-coated layer 30 is provided with a lower layer 34 and an upper layer 32. The upper layer 32 contains Rh and/or Pt as a noble metal catalyst. The lower layer 34 contains Pd as a noble metal catalyst. The lower layer 34 is provided with a front-stage lower layer 34a positioned on an upstream side and a rear-stage lower layer 34b positioned on a downstream side. The front-stage lower layer 34a is a Ce-free layer that does not contain a Ce-containing oxide. The rear-stage lower layer 34b is a Ce-containing layer that contains a Ce-containing oxide with a pyrochlore structure.

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; a noble metal supported on the honeycomb structured body; and an inlet-side end face and on outlet-side end face, wherein each partition wall includes a substrate portion in the form of an extrudate containing a ceria-zirconia complex oxide and alumina, and a coat layer formed on a surface of the substrate portion and containing the noble metal, and the inlet-side end face has a higher aperture ratio than the outlet-side end face.