Hydrocarbon trap/catalyst for reducing cold-start emissions from internal combustion engines
AssigneeJohnson Matthey Public Limited Company
InventorsTodd Howard Ballinger, Paul Joseph Andersen
Life of this patent
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Abstract
An active metal, particularly cesium, impregnated hydrocarbon adsorbent, such as zeolite, comprises an improved hydrocarbon trap/oxidizing catalyst for use in effectively adsorbing hydrocarbons during automotive cold-start and subsequently desorbing, oxidizing and removing hydrocarbons during warmer operating conditions. The active metal modified hydrocarbon adsorbent may be combined in other forms of multi-layer automotive exhaust gas catalytic structures.
Claims23
A catalyst structure comprising:
- (a) a first layer consisting essentially of a hydrocarbon-adsorbing zeolite and an active metal selected from the group consisting of potassium, rubidium, and cesium, wherein said active metal is impregnated on said zeolite;
- (b) at least one additional layer consisting essentially of at least one platinum group metal;
- and
- (c) a catalyst substrate, on which said first layer and said at least one additional layer are disposed.
A catalyst structure comprising:
- (a) a first layer consisting essentially of a hydrocarbon-adsorbing zeolite and an active metal selected from the group consisting of potassium, rubidium, and cesium, wherein said active metal is impregnated on said zeolite;
- (b) at least one additional layer consisting of at least one platinum group metal and an additional component selected from the group consisting of at least one of a high temperature catalyst, a low temperature catalyst, and a metal oxide additive;
- and
- (c) a catalyst substrate, on which said first layer and said at least one additional layer are disposed.
A catalyst structure comprising:
- (a) a first layer consisting essentially of a hydrocarbon-adsorbing zeolite and an active metal selected from the group consisting of potassium, rubidium, and cesium, wherein said active metal is impregnated on said zeolite;
- (b) a second layer overlying said first layer and consisting of at least one platinum group metal selected from the group consisting of platinum, palladium, rhodium, ruthenium and iridium, zirconium stabilized ceria, lanthanum stabilized alumina, and at least one metal oxide additive;
- (c) a third layer consisting of at least one platinum group metal selected from the group consisting of platinum, palladium, rhodium, ruthenium and iridium, ceria stabilized zirconia, and lanthanum stabilized alumina;
- (d) a catalyst substrate, on which said first layer, said second layer, and said third layer are disposed.
A method of making a catalyst comprising the steps of:
- (a) preparing a slurry containing a hydrocarbon-adsorbing zeolite;
- (b) applying said slurry to a catalyst support substrate to form a first layer thereon;
- (c) impregnating said first layer with a solution of a soluble salt of an active metal selected from the group consisting of potassium, rubidium, and cesium;
- (d) heating said first layer to dryness;
- and
- (e) applying to said first layer a second layer consisting essentially of at least one platinum group metal.
A method of making a catalyst comprising the steps of:
- (a) preparing a slurry containing a hydrocarbon-adsorbing zeolite;
- (b) applying said slurry to a catalyst support substrate to form a first layer thereon;
- (c) impregnating said first layer with a solution of a soluble salt of an active metal selected from the group consisting of potassium, rubidium, and cesium;
- (d) heating said first layer to dryness;
- and
- (e) applying to said first layer a second layer consisting of at least one platinum group metal and an additional component selected from the group consisting of at least one of a high temperature catalyst, a low temperature catalyst, and a metal oxide additive.
Dependencies are inferred from the claim text.