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.

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.

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.

Disclosed herein are compositions containing zirconium and cerium having a surprisingly small particle size. The compositions disclosed herein contain zirconium, cerium, optionally yttrium, and optionally one or more other rare earth oxides other than cerium and yttrium. The compositions exhibit a particle size characterized by a D.sub.90 value of about 5 μm to about 30 μm and a D.sub.99 value of about 5 um to about 40 um. Further disclosed are processes of producing these compositions using oxalic acid and supercritical drying in the process. The compositions can be used as a catalyst and/or part of a catalytic system. The composition is prepared by co-precipitation using oxalic acid and supercritical drying.

Disclosed herein are compositions containing zirconium and cerium having a surprisingly small particle size. The compositions disclosed herein contain zirconium, cerium, optionally yttrium, and optionally one or more other rare earth oxides other than cerium and yttrium. The compositions exhibit a particle size characterized by a D.sub.90 value of about 5 μm to about 30 μm and a D.sub.99 value of about 5 um to about 40 um. Further disclosed are processes of producing these compositions using oxalic acid and supercritical drying in the process. The compositions can be used as a catalyst and/or part of a catalytic system. The composition is prepared by co-precipitation using oxalic acid and supercritical drying.

A honeycomb-structured catalyst for decomposing an organic substance, which includes a catalyst particle. The catalyst particle contains a perovskite-type composite oxide represented by A.sub.xB.sub.yM.sub.zO.sub.w, where the A contains at least of Ba and Sr, the B contains Zr, the M is at least one of Mn, Co, Ni, and Fe, y+z=1, 1.001≤x≤1.05, 0.05≤z≤0.2, and w is a positive value that satisfies electrical neutrality. The toluene decomposition rate is greater than 90% when toluene is decomposed using the honeycomb-structured catalyst subjected to a heat treatment at 1200° C. for 48 hours and a gas that contains 50 ppm toluene, 80% nitrogen, and 20% oxygen as a volume concentration as a target at a space velocity of 30,000/h and a catalyst temperature of 400° C.

A honeycomb-structured catalyst for decomposing an organic substance, which includes a catalyst particle. The catalyst particle contains a perovskite-type composite oxide represented by A.sub.xB.sub.yM.sub.zO.sub.w, where the A contains at least of Ba and Sr, the B contains Zr, the M is at least one of Mn, Co, Ni, and Fe, y+z=1, 1.001≤x≤1.05, 0.05≤z≤0.2, and w is a positive value that satisfies electrical neutrality. The toluene decomposition rate is greater than 90% when toluene is decomposed using the honeycomb-structured catalyst subjected to a heat treatment at 1200° C. for 48 hours and a gas that contains 50 ppm toluene, 80% nitrogen, and 20% oxygen as a volume concentration as a target at a space velocity of 30,000/h and a catalyst temperature of 400° C.

A method of manufacturing a catalyst intermediate is provided. The method comprises: providing a slurry comprising a hydrous oxide of one or more of aluminium, cerium and zirconium; and contacting the slurry comprising a hydrous oxide with platinum group metal (PGM) ions to provide a PGM-containing slurry.

A method of manufacturing a catalyst intermediate is provided. The method comprises: providing a slurry comprising a hydrous oxide of one or more of aluminium, cerium and zirconium; and contacting the slurry comprising a hydrous oxide with platinum group metal (PGM) ions to provide a PGM-containing slurry.