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; and a noble metal supported on the honeycomb structured body, wherein the honeycomb structured body contains a ceria-zirconia complex oxide and alumina, each partition wall includes a first carrier layer defining a surface layer of the partition wall and carrying Pd, and a second carrier layer located more inwardly of the partition wall than the first carrier layer and carrying Rh.

The present invention provides 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; and a noble metal supported on the honeycomb structured body, wherein the honeycomb structured body contains a ceria-zirconia composite oxide and alumina, and cerium on a surface of each partition wall has a lower concentration than cerium in a central portion of the partition wall in a thickness direction.

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 and an outlet end with an axial length L; a first catalytic region comprising a first palladium (Pd) component and a first Pd support material, wherein the substrate is substantially free of the first Pd component.

An exhaust gas purification catalyst including at least two layers, a lower catalyst layer and upper catalyst layer, on a refractory three-dimensional structure, wherein the lower catalyst layer and upper catalyst layer independently include a precious metal, alumina, and cerium-zirconium composite oxide, and at least a portion of the upper catalyst layer is formed using a manufacturing method including: applying a slurry for forming the upper catalyst layer onto the lower catalyst layer, the slurry containing a pore connecting agent with a combustion decomposition temperature of 150° C. or more to 400° C. or less, a precious metal precursor, alumina, and cerium-zirconium composite oxide, the content ratio of the pore connecting agent being less than 20 mass % of the total solid content when heated to 1000° C.; and holding the workpiece in an oxygen containing gas at a temperature above −150° C. and +50° C. or lower, relative to the combustion decomposition temperature.

An exhaust gas purification device includes a substrate including an upstream end and a downstream end and having a length Ls; a first containing Pd particles, extending between the upstream end and a first position, and being in contact with the substrate; a second containing Rh particles, extending between the downstream end and a second position, and being in contact with the substrate; and a third catalyst layer containing Rh particles, extending between the upstream end and a third position, and being in contact with at least the first catalyst layer, wherein an average of a Rh particle size distribution is from 1.0 to 2.0 nm, and a standard deviation of the Rh particle size distribution is 0.8 nm or less in each of the second catalyst layer and the third catalyst layer.

An exhaust gas purification underfloor catalyst characterized in having a catalyst layer having a lower layer and an upper layer, the lower layer containing alumina and CeO.sub.2, the noble metal content of the lower layer being at most 0.5 mass % in relation to the mass of the lower layer, the upper layer containing Rh, alumina, and CeO.sub.2, the amount of noble metals other than Rh contained being 1 mol % or less in relation to the total amount of noble metals contained in the upper layer, the total amount of CeO.sub.2 contained in the lower layer and the upper layer being 14 g/L to 30 g/L, the amount of CeO.sub.2 contained in the upper layer being 7 g/L to 25 g/L, and the amount of CeO.sub.2 contained in the lower layer being 20% or more of the amount of CeO.sub.2 contained in the upper layer.

A nitrous oxide (N.sub.2O) removal catalyst composite is provided, comprising a N.sub.2O removal catalytic material on a substrate, the catalytic material comprising a rhodium (Rh) component supported on a ceria-based support, wherein the catalyst composite has a H.sub.2-consumption peak of about 100° C. or less as measured by hydrogen temperature-programmed reduction (H.sub.2-TPR). Methods of making and using the same are also provided.

The invention relates to a catalyst which comprises a carrier substrate, palladium, and a zeolite, the largest channels of which are formed by 10 tetradrically coordinated atoms; to the use of said catalyst as a passive nitrogen oxide adsorber, an exhaust gas system which contains said catalyst and an SCR catalyst, and to a method for purifying the exhaust gas of motor vehicles using said exhaust gas system.

An exhaust gas purification catalyst device has catalyst coating layers, which extend from the upstream side to the downstream side of the exhaust gas flow. The catalyst coating layers each have at least three zones present in order from the upstream side to the downstream side of the exhaust gas flow, and each of these at least three zones is an oxidation catalyst zone or a reduction catalyst zone. In the uppermost layer of an oxidation catalyst zone, the total number of atoms of platinum and palladium is greater than the number of atoms of rhodium; in the upper most layer of a reduction catalyst zone, the number of atoms of rhodium is greater than the total number of atoms of platinum and palladium. The oxidation catalyst zones and the reduction catalyst zones alternate at least twice in the exhaust gas flow direction.

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.