Catalyst for the purification of exhaust gases and process for preparing the catalyst

Claim 2

A CATALYST FOR PURIFYING EXHAUST GASES CONTAINING AT LEAST ONE OF CARBON MONOXIDE, UNBURNED HYDROCARBON AND NITROGEN OXIDE WHICH CONSISTS ESSENTIALLY OF A BASE CONSISTING OF IRON OR STEEL, AN IRON-ALUMINUM ALLOY PROVIDED ON THE SURFACE OF SAID BASE AND A PLATINUM GROUP METAL SUPPORTED ON SAID ALLOY; AN AVERAGE RATIO OF IRON AND ALUMINUM IN SAID ALLOY FALLING WITHIN THE RANGE OF ABOUT 1:10 TO ABOUT 10:1 BY ATOMIC RATIO AND SAID PLATINUM GROUP METAL BEING SUPPORTED IN AN AMOUNT OF ABOUT 0.02 TO ABOUT 20 G./SQUARE METER OF APPARENT SURFACE AREA, WHEREIN THE APPARENT SURFACE AREA IS LESS THAN THE ACTUAL SURFACE AREA.

Claim 3

The catalyst of claim 1, wherein said iron-aluminum alloy has an actual surface area of more than 2 times the apparent surface area and said catalyst has an actual surface area of more than 5 times the apparent surface area.

Claim 4

The catalyst of claim 1, wherein said iron-aluminum alloy has an actual surface area of more than 2 times the apparent surface area and said catalyst has an actual surface area in the range of 30 to 300 times the apparent surface area.

Claim 5

The catalyst of claim 1, wherein said iron-aluminum alloy contains a large number of hollows having an average diameter in the range of 10 to 100 Mu and has a surface area of more than 2 times the apparent surface area.

Claim 6

The catalyst of claim 1, wherein said platinum group metal is at least one selected from the group consisting of platinum and palladium.

Claim 7

The catalyst of claim 1, wherein said base is steel base.

Claim 8

The catalyst of claim 6, wherein said steel base is stainless steel base.

Claim 9

The catalyst of claim 6, wherein said steel base is wire gauze made of stainless steel.

Claim 10

A process for preparing catalyst for the purification of exhaust gases containing at least one of carbon monoxide, unburned hydrocarbon and nitrogen oxide, which comprises applying a coating composition consisting essentially of aluminum powder and organic solvent on the surface of a base consisting of iron or steel, drying said composition, heating said base applied with aluminum at a temperature of about 500* to about 1,000*C for more than 1 minute to form an iron-aluminum alloy on said base and then supporting a platinum group metal on said alloy to give a catalyst consisting essentially of said base, sAid alloy on said base and said platinum group metal on said alloy; an average ratio of iron and aluminum in said alloy falling within the range of about 1:10 to about 10:1 by atomic ratio and said platinum group metal being supported in an amount of about 0.02 to about 20 g./square meter of apparent surface area, wherein the apparent surface area is less than the actual surface area.

Claim 11

A process for preparing catalyst for the purification of exhaust gases containing at least one of carbon monoxide, unburned hydrocarbon and nitrogen oxide, which comprises applying a coating composition consisting essentially of aluminum powder and organic solvent on the surface of a base consisting of iron or steel, drying said composition, heating said base applied with aluminum at a temperature of about 500* to about 1,000*C for more than 1 minute to form an iron-aluminum alloy on said base and then supporting a platinum group metal on said alloy to give a catalyst consisting essentially of said base, sAid alloy on said base and said platinum group metal on said alloy; an average ratio of iron and aluminum in said alloy falling within the range of about 1:10 to about 10:1 by atomic ratio and said platinum group metal being supported in an amount of about 0.02 to about 20 g./square meter of apparent surface area, wherein the apparent surface area is less than the actual surface area.