The oxide-containing particles (transition metal oxide-containing cerium dioxide particle) exert a catalyst performance, and include at least an iron oxide containing an iron component and a manganese oxide containing a manganese component on a surface of each of cerium dioxide particles, wherein the iron oxide and manganese oxide have smaller particle diameters than that of the cerium dioxide particles, and the content rate of the iron oxide and the manganese oxide is within the range of from 15.0% by mass to 35.0% by mass.

Provided is an exhaust gas purification catalyst in which the performance of a catalyst metal can be brought out properly, the purification catalyst boasting excellent purification performance during warm-up of an internal combustion engine. The exhaust gas purification catalyst 10 is provided with a substrate 1 and a catalyst layer. A leading end section 1a positioned upstream in the direction of exhaust gas flow (arrow) has a portion in which the flow rate of exhaust gas is relatively high and a portion in which the flow rate of exhaust gas is relatively low during warm-up of the internal combustion engine. The catalyst, layer in the portion of relatively high flow rate of exhaust gas has a high density section 6 in which a noble metal, is supported at relatively high density. The high density section 6 is formed to be shorter than the total length of the exhaust gas purification catalyst 10 from the leading end section 1a in the direction of exhaust gas flow.

Provided is a powder inorganic oxide containing Al, Ce and Zr as constituent elements, that affords a molded product with a density of 1.0 to 1.3 g/ml by placing 4.0 g of the inorganic oxide in a cylindrical container having diameter 20 mm and performing uniaxial molding under conditions of room temperature and pressure of 29.4 MPa for 30 sec., and achieves an average shrinkage percentage of not more than 14.0% as calculated by the following formula: average shrinkage percentage (%)=100×{(1−(c)/(a))+(1−(d)/(b))}/2 wherein each symbol is as defined in the DESCRIPTION.

In an exhaust gas purification system provided with a denitration catalyst layer, a reducing agent oxidation catalyst layer is installed together; a reducing agent and air are supplied into the reducing agent oxidation catalyst layer at the time of catalyst regeneration of the denitration catalyst layer; a high-temperature oxidation reaction gas is produced by a reaction heat generated by an oxidation reaction of the reducing agent and the air in this reducing agent oxidation catalyst layer; and this high-temperature oxidation reaction gas is introduced into the denitration catalyst layer to heat the denitration catalyst, thereby recovering a denitration performance of the catalyst.

A drip-irrigation catalytic reduction exhaust pipe includes an exhaust pipe having a pipe wall in which a plurality of first apertures is formed and a plurality of direct-through ceramic filters arranged in the exhaust pipe in an axial direction from an exhaust gas inlet opening toward the exhaust gas outlet opening, or alternatively, a wall-flow filter being arranged at a location that is closest to the exhaust gas outlet opening. A flow guide tube is arranged outside the exhaust pipe and is connected to a container and includes a plurality of second apertures. The second apertures respectively correspond to the first apertures. An electromagnetic valve controls passage of urea liquid contained in the container through the second apertures and the first apertures to drip into the exhaust pipe and absorbed by a ceramic fiber material for penetration into pores of the direct-through ceramic filters and the wall-flow filter.

The present invention is directed to a certain method of catalytically coating a honeycomb monolith, in particular a so-called flow-through monolith. These types of monoliths can be quite precisely be coated by a method using an indirect coating via a displacement body. The present invention further improves this method through controlling the process by monitoring the certain measures.

The present invention pertains to a catalyst for use in the selective catalytic reduction (SCR) of nitrogen oxides comprising: • a monolithic substrate and • a coating A which comprises an oxidic metal carrier comprising an oxide of titanium and a catalytic metal oxide which comprises an oxide of vanadium wherein the mass ratio vanadium/titanium is 0.07 to 0.26.

A fluid feed ring (5), a substrate coating apparatus (1) and a method are provided for coating a substrate (2) with a catalyst component. The fluid feed ring (5) comprises an annular body (40) having an inner face (45) bounding a central bore of the fluid feed ring. A fluid feed port (47) receives the liquid and a plurality of outlet apertures (50) on the inner face of the annular body discharge the liquid onto a piston face (23) of the substrate coating apparatus (1). A distribution channel (51) extending at least part-way around the annular body (40) provides fluid communication between the fluid feed port (47) and the plurality of outlet apertures (50).

An exhaust system for a combustion engine includes first and second catalytic converters arranged downstream of the combustion engine in a flow direction of exhaust gas. First and second exhaust pipes extend from the combustion engine to the first and second catalytic converters, respectively, with a first valve disposed in the first exhaust pipe, and a second valve disposed in the second exhaust pipe. The first and second valves operate such that in the presence of an exhaust temperature which is equal to or less than a limit value, at least the first valve opens to allow exhaust gas from the combustion engine to flow through the first catalytic converter, and that the first valve closes and the second valve opens, when the exhaust temperature is greater than the limit value to thereby allow exhaust gas from the combustion engine to flow through the second catalytic converter.

This catalyst system simultaneously removes ammonia and enhances net NOx conversion by placing an NH.sub.3-SCR catalyst formulation downstream of a lean NOx trap. By doing so, the NH.sub.3-SCR catalyst adsorbs the ammonia from the upstream lean NOx trap generated during the rich pulses. The stored ammonia then reacts with the NOx emitted from the upstream lean NOx trap-enhancing the net NOx conversion rate significantly, while depleting the stored ammonia. By combining the lean NOx trap with the NH.sub.3-SCR catalyst, the system allows for the reduction or elimination of NH.sub.3 and NOx slip, reduction in NOx spikes and thus an improved net NOx conversion during lean and rich operation.