The present invention relates to cerium oxide particles that have excellent heat resistance under hydrothermal conditions at high temperature. The present invention also relates to a method for preparing such cerium oxide particles and to a catalytic composition comprising said cerium oxide.

Provided is a system for treating a flowing exhaust gas comprising a lean NOx trap, a catalyzed soot filter, an ammonia or an ammonia precursor metering system for metering ammonia or an ammonia precursor into the flowing exhaust gas; and an SCR catalyst, wherein the SCR catalyst is disposed downstream of the lean NOx trap and comprises copper and/or iron supported on a small pore molecular sieve.

The present invention relates to a catalyst comprising a carrier substrate of length L, coating A arranged as the first layer on the carrier and containing platinum on a metal oxide, and coating B applied as the second layer to coating A and containing a Cu-exchanged molecular sieve and no noble metal, wherein the total washcoat quantity of coating A is 40 g/l or more of washcoat in relation to the coated catalyst volume.

An exhaust gas purification filter comprises a base material part, a catalyst layer, and sealing parts. The base material part comprises porous partition walls. The catalyst layer is supported on pore walls of the partition walls. The partition walls supporting the catalyst layer comprise 10% or less of pores having a pore diameter of 50 μm or more. In the pore diameter distribution in the partition walls supporting the catalyst layer, the pore diameter D50 at which the cumulative pore volume becomes 50% is 10 μm or more. The pore diameter D50, and the pore diameter D10 at which the cumulative pore volume becomes 10%, satisfy the relationship of the following Expression 1.

(D50−D10)/D50≤0.9  Expression 1

The exhaust gas purification device is provided with a wall flow structure substrate that has an entry-side cell, an exit-side cell and a porous partition, first catalyst parts which are formed in small pores having a relatively small pore diameter among internal pores in the partition, and second catalyst parts which are formed in large pores having a relatively large pore diameter among the internal pores in the partition. The first catalyst parts and the second catalyst parts each contain a carrier and at least one type of noble metal from among Pt, Pd and Rh supported on the carrier. The noble metal content in the first catalyst parts is smaller than the noble metal content in the second catalyst parts per 1 liter of substrate volume.

A method for the manufacture of a catalyst comprising substrate particles having gold nanoparticles thereon, the method comprising providing a first solution comprising gold nanoparticles; providing a second solution comprising substrate particles having polyelectrolyte on the surface thereof; and combining the solutions to form substrate particles having gold nanoparticles thereon. A catalyst comprising substrate particles having gold nanoparticles thereon, wherein the gold nanoparticles comprise capping agent comprising polyelectrolyte. A catalyst as a component of a cigarette filter, an air conditioning unit, an exhaust, or a diesel exhaust.

An exhaust gas purification catalyst is provided for which a purification performance is excellent and particle growth of a catalyst metal is suppressed. The exhaust gas purification catalyst is provided with a substrate and a catalyst layer formed on the substrate. The catalyst layer contains a catalyst metal that functions as an oxidation and/or reduction catalyst and contains a support that supports the catalyst metal. The support is constituted of a porous ceramic that, in its volumetric pore diameter distribution measured based on a nitrogen gas adsorption method, has a pore diameter P.sub.10 corresponding to a cumulative 10% from a small pore side and a pore diameter P.sub.90 corresponding to a cumulative 90% from the small pore side that are both in a range from 5 to 50 nm.

An exhaust gas purification catalyst having an excellent exhaust partition ability while reducing the increase in pressure loss. Exhaust gas purification catalyst includes a substrate having a wall-flow structure with partition wall, upstream coating section formed in portions of partition wall facing entrance cell, from exhaust inlet-side end in the extending direction of partition wall, and downstream coating section formed in portions of partition wall facing exit cell, from exhaust outlet-side end in the extending direction, having a length shorter than the entire length L.sub.w of the partition wall. In downstream coating section, a catalytic metal is concentrated in the surface layer in contact with exit cell.

An exhaust gas-purifying catalyst of the present invention comprises a substrate, and one or more catalytic layers provided on the substrate, wherein at least one of the catalytic layers (i) contains a precious metal, alumina, and an acidic oxide element, (ii) has a correlation coefficient ρ.sub.Al,AE of 0.70 or more, and (iii) has a correlation coefficient ρ.sub.PM,AE of 0.70 or more.

A ceramic honeycomb structure comprising large numbers of flow paths longitudinally formed by cell walls arranged in a lattice pattern in cross section, and an outer peripheral wall formed around the flow paths; in a cross section perpendicular to the longitudinal direction, fan-shaped bulges projecting in a fan shape toward the flow paths from cell wall intersections at which the cell walls are crossing; the circumscribed circles of circular portions of the fan-shaped bulges at all cell wall intersections having a constant radius; and when the distance between the center point of the circumscribed circle and the center point of the cell wall intersection is defined as a center point distance S, a center point distance So in the outer peripheral portion of the ceramic honeycomb structure and a center point distance Sc in the center portion meeting Sc<So.