The exhaust gas purification catalyst device includes an upper layer which includes first carrier particles and rhodium, and a lower layer which includes second carrier particles, and the upper layer includes a rhodium enriched area in the range a, from the upstream end in the exhaust gas flow to 50% of the upper layer length, and a range b from the upper layer top surface to 18 μm in the depth direction. The rhodium enriched area contains at least 50% and less than 100% of all the rhodium in the upper layer.

Provided is a composition for catalyst production which is used in the production of a catalyst for gas phase catalytic oxidation reaction or a catalyst for gas phase catalytic ammoxidation reaction, wherein the composition for catalyst production is an aqueous solution containing a niobium compound and hydrogen peroxide and optionally containing an organic acid, a molar ratio (organic acid/Nb) of a concentration of the organic acid to a Nb concentration is 0.00 or more and 2.00 or less, and a molar ratio (hydrogen peroxide/Nb) of a concentration of the hydrogen peroxide to a Nb concentration is 0.01 or more and 50 or less.

Provided is a composition for catalyst production which is used in the production of a catalyst for gas phase catalytic oxidation reaction or a catalyst for gas phase catalytic ammoxidation reaction, wherein the composition for catalyst production is an aqueous solution containing a niobium compound and hydrogen peroxide and optionally containing an organic acid, a molar ratio (organic acid/Nb) of a concentration of the organic acid to a Nb concentration is 0.00 or more and 2.00 or less, and a molar ratio (hydrogen peroxide/Nb) of a concentration of the hydrogen peroxide to a Nb concentration is 0.01 or more and 50 or less.

A cerium-zirconium-aluminum-based composite material, a cGPF catalyst and a preparation method thereof are provided. The cerium-zirconium-aluminum-based composite material adopts a stepwise precipitation method, firstly preparing an aluminum-based pre-treated material, then coprecipitating the aluminum-based pre-treated material with zirconium and cerium sol, and finally roasting at high temperature to obtain the cerium-zirconium-aluminum-based composite material. The cerium-zirconium-aluminum-based composite material has better compactness and higher density, and when it is used in cGPF catalyst, it occupies a smaller volume of pores on the catalyst carrier, such that cGPF catalyst has lower back pressure and better ash accumulation resistance, which is beneficial to large-scale application of cGPF catalyst.

A cerium-zirconium-aluminum-based composite material, a cGPF catalyst and a preparation method thereof are provided. The cerium-zirconium-aluminum-based composite material adopts a stepwise precipitation method, firstly preparing an aluminum-based pre-treated material, then coprecipitating the aluminum-based pre-treated material with zirconium and cerium sol, and finally roasting at high temperature to obtain the cerium-zirconium-aluminum-based composite material. The cerium-zirconium-aluminum-based composite material has better compactness and higher density, and when it is used in cGPF catalyst, it occupies a smaller volume of pores on the catalyst carrier, such that cGPF catalyst has lower back pressure and better ash accumulation resistance, which is beneficial to large-scale application of cGPF catalyst.

An object of the present invention is to provide means for releasing oxygen at a temperature lower than conventional means in an exhaust gas purification catalyst. A Ce—Zr composite oxide is provided, which has a crystallite diameter of 6.5 nm or less and a BET specific surface area of 90 m.sup.2/g or more.

An object of the present invention is to provide means for releasing oxygen at a temperature lower than conventional means in an exhaust gas purification catalyst. A Ce—Zr composite oxide is provided, which has a crystallite diameter of 6.5 nm or less and a BET specific surface area of 90 m.sup.2/g or more.

An integrated filter material, a preparation method and an application. The filter material is composed of a commercial dust removal filter material and a catalyst that is grown on the filter material and that has a function of simultaneously decomposing nitrogen oxides and dioxins. In the preparation method, a precursor solution of manganese and cerium oxides is impregnated on the filter material, and manganese and cerium oxides are grown on the filter material by means of a chemical reaction; and vanadium oxychloride is used as a precursor of vanadium oxide and is impregnated on the filter material, reacts in water, and prepared by drying, hydrothermal and other processes. The composite filter material may remove three kinds of pollutants in flue gas at the same time, and the catalyst is firmly loaded and does not easily fall off.

An integrated filter material, a preparation method and an application. The filter material is composed of a commercial dust removal filter material and a catalyst that is grown on the filter material and that has a function of simultaneously decomposing nitrogen oxides and dioxins. In the preparation method, a precursor solution of manganese and cerium oxides is impregnated on the filter material, and manganese and cerium oxides are grown on the filter material by means of a chemical reaction; and vanadium oxychloride is used as a precursor of vanadium oxide and is impregnated on the filter material, reacts in water, and prepared by drying, hydrothermal and other processes. The composite filter material may remove three kinds of pollutants in flue gas at the same time, and the catalyst is firmly loaded and does not easily fall off.

The present invention relates to a mixed oxide of aluminium, of zirconium, of cerium, of lanthanum and optionally of at least one rare-earth metal other than cerium and lanthanum that makes it possible to prepare a catalyst that retains, after severe ageing, a good thermal stability and a good catalytic activity. The invention also relates to the process for preparing this mixed oxide and also to a process for treating exhaust gases from internal combustion engines using a catalyst prepared from this mixed oxide.