The present disclosure provides a three-way conversion (TWC) catalyst composition suitable for at least partial conversion of gaseous hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx). Generally, the catalyst composition comprises a platinum group metal component impregnated into a porous refractory oxide support, wherein the porous refractory oxide support has an average pore radius ranging from about 250 ? to about 5,000 ?, a total intrusion volume of at least about 1.8 ml/g, and a porosity of at least about 80%.

An exhaust gas purifying catalyst having first carrier particles, second carrier particles, and precious metal catalyst particles supported on the first and second carrier particles, wherein: the first carrier particles contain ceria, zirconia, and a rare-earth oxide other than ceria; the second carrier particles contain a rare-earth oxide other than ceria, and may contain ceria and zirconia; the contained proportion of ceria and zirconia in the first carrier particles is higher than the contained proportion of ceria and zirconia in the second carrier particles; the contained proportion of the rare-earth oxide in the second carrier particles is higher than the contained proportion of the rare-earth oxide in the first carrier particles; and the contained proportion of ceria in the first carrier particles is 45 wt % or less, while the precious metal catalyst particles include rhodium particles.

Composites of mixed metal oxides for an exhaust gas purifying catalyst comprise the following co-precipitated materials by weight of the composite: zirconia in an amount in the range of 55-99%; titania in an amount in the range of 1-25%; a promoter and/or a stabilizer in an amount in the range of 0-20%. These composites are effective as supports for platinum group metals (PGMs), in particular rhodium.

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; and a single catalyst layer deposited directly on the substrate; wherein the single catalyst layer comprises a first platinum group metal (PGM) component, an oxygen storage component (OSC) material, and an inorganic oxide; and wherein the single catalyst layer has a total washcoat loading of less than 2.4 g/in.sup.3.

In the plugged honeycomb structure, 30% or more of first intersection portions in which a first partition wall intersects a second partition wall are first specific intersection portions in which a diameter of a maximum inscribed circle drawn in the first intersection portion is a specific size for a shortest distance between an inflow cell and an outflow cell, and 30% or more of non-first intersection portions other than the first intersection portions are non-first specific intersection portions in which a diameter of a maximum inscribed circle drawn in a non-first intersection portion is a specific size for a shortest distance between the inflow cells or the outflow cells.

A honeycomb structural body 20 comprises a porous partition portion 22 which forms a plurality of cells each functioning as a flow path of a fluid, and in the partition portion 22, the average pore diameter is 10 to 20 m, and a wet area rate R (=S/V) which is the rate of a wet area S of pores to a volume V of the partition portion 22 is 0.000239 m.sup.1 or more.

Provided is an exhaust gas purification filter including a substrate comprising a plurality of porous partitions, wherein the partitions form an exhaust gas flow path, a porous catalytic layer is provided on the partitions and the catalytic layer having a thickness of 10 m or greater is provided over at least 20% of the total length of the partitions in the lengthwise direction thereof, and the catalytic layer having a thickness of 10 m or greater is not present on the partitions 15 mm from an outflow side.

A catalyst composition comprising an intermetallic compound is disclosed. The intermetallic compound comprises a transition metal selected from Fe, Ce, Y, Nb and combinations thereof; and a noble metal selected from Pt, Pd, Rh and combinations thereof. The invention further relates to a washcoat comprising the catalyst composition, and a catalyst article comprising the catalyst composition, a method of treating exhaust gas with the catalyst article, a method for manufacturing the catalyst article and systems comprising the catalyst article.

Provided is a hydrocarbon reduction catalyst including a carrier including a cerium-zirconium composite oxide, and palladium supported on the carrier, wherein the palladium is included in an amount of about 1 wt % to about 10 wt % based on a total weight of the catalyst.

An exhaust gas purification device suppresses a pressure loss increase and includes a honeycomb substrate and inflow cell side catalyst layer. The substrate includes a porous partition wall defining several cells extending from an inflow side end surface to an outflow side end surface. The cells include an inflow and outflow cell adjacent across the wall. The inflow cell has an open inflow side end and sealed outflow side end. The outflow cell has a sealed inflow side end and open outflow side end. The catalyst layer is on an inflow cell side surface in an region extending from the inflow side end positioned 10% or more of the partition wall length. At this position, a filled portion of the inflow cell side catalyst layer pores are 40% or less. The pores are present to a depth of 50% of a thickness of the partition wall.