Process for production of a catalyst having excellent heat resistance for use in purifying exhaust gases from internal combustion engines

Claim 2

An exhaust gas purifying catalyst comprising a monolithic support and being present thereon, at least one platinum-group element, active alumina, cerium oxide, a barium compound and a zirconium compound as catalyst ingredients.

Claim 3

The catalyst set forth in claim 1 wherein the monolithic support is of a honeycomb-like or three-dimensional network structure.

Claim 4

The catalyst set forth in claim 1 or 2 wherein the monolithic support is composed of cordierite.

Claim 5

The catalyst set forth in claim 1 or 2 wherein the monolithic support is composed of a refractory metal.

Claim 6

The catalyst set forth in any one of claims 1 to 4 wherein the platinum-group element consists of platinum and rhodium.

Claim 7

The catalyst set forth in any one of claims 1 to wherein the weight of platinum is 0.1 to 10 g per liter of the finished catalyst.

Claim 8

The catalyst set forth in any one of claims 1 to 6 wherein the weight of rhodium is 0.02 to 2 g per liter of the finished catalyst.

Claim 9

The catalyst set forth in any one of claims 1 to 7 wherein the weight of active alumina is 30 to 200 g per liter of the finished catalyst.

Claim 10

The catalyst set forth in any of claims 1 to 8 wherein the weight of cerium oxide is 10 to 150 g per liter of the finished catalyst.

Claim 11

The catalyst set forth in any one of claims 1 to 9 wherein the barium compound consists of barium hydroxide, barium oxide and barium carbonate either alone or in combina­tion.

Claim 12

The catalyst set forth in any one of claims 1 to 10 wherein the weight of the barium compound is 0.1 to 20 g calculated as barium oxide per liter of the finished catalyst.

Claim 13

The catalyst set forth in any one of claims 1 to 11 wherein the zirconium compound is zirconium oxide.

Claim 14

The catalyst set forth in any one of claims 1 to 12 wherein the weight of the zirconium compound is 0.1 to 30 g calculated as zirconium oxide per liter of the finished catalyst.

Claim 15

A process for producing an exhaust gas purify­ing catalyst according to any preceding claim by depositing a slurry containing at least one platinum-group element, active alumina, cerium oxide, a barium compound and a zirconium compound as catalyst ingredients on a monolithic support and calcining the support having the cata­lyst ingredient deposited thereon, which comprises (a) a step of preparing active alumina containing the platinum-group element, (b) a step of preparing a slurry containing the platinum-group element, active alumina, cerium oxide, the barium compound and the zirconium compound, and (c) a step of depositing the slurry on the monolithic support, followed by calcination.

Claim 16

The process set forth in claim 14 wherein the barium compound is barium hydroxide.

Claim 17

The process set forth in claim 14 or claim 15 wherein the zirconium compound is zirconyl acetate.

Claim 18

The process of any one of claims 14 to 16 wherein the weight of the zirconium compound is 0.1 to 30 g calculated as zirconyl acetate per liter of the finished catalyst.