Method of treating diesel exhaust gases
First Claim
1. A diesel exhaust gas treatment system comprising:
- an oxidation catalyst positioned in an exhaust gas passage of a diesel engine for converting at least a portion of NO contained in said exhaust gas to NO2 at a temperature between about 175°
C. to 250°
C., said oxidation catalyst comprising platinum and a support material comprising zirconia-silica, said support material having strong acid sites; and
a particulate filter for receiving said exhaust gas.
3 Assignments
0 Petitions
Accused Products
Abstract
A diesel exhaust treatment system and method of oxidizing NO to NO2 at low temperatures are provided. The system utilizes a platinum catalyst on a zirconia-stabilized silica support which oxidizes NO in the exhaust gas to NO2 and uses the NO2 in an amount sufficient to oxidize particulate trapped on a particulate filter. The catalyst is preferably pre-treated at a temperature of between about 500 to 650° C. in a NO-oxygen-nitrogen mixture to increase conversion at low temperatures. The catalyst preferably includes an additional oxide component selected from the group consisting of TiO2, P2O5, WO3, B2O3, and Al2O3. or a heteropolyacid component to further increase activity at low temperatures or to decrease platinum loading at the same level of performance.
-
Citations
26 Claims
-
1. A diesel exhaust gas treatment system comprising:
-
an oxidation catalyst positioned in an exhaust gas passage of a diesel engine for converting at least a portion of NO contained in said exhaust gas to NO2 at a temperature between about 175°
C. to 250°
C., said oxidation catalyst comprising platinum and a support material comprising zirconia-silica, said support material having strong acid sites; and
a particulate filter for receiving said exhaust gas. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
-
11. A method for treating diesel exhaust gases comprising:
-
positioning an oxidation catalyst in an exhaust gas passage of a diesel engine, said oxidation catalyst comprising platinum and a support material comprising zirconia-stabilized silica, said support material having strong acid sites;
providing a particulate filter downstream of said oxidation catalyst;
exposing said oxidation catalyst to diesel exhaust gas containing NO such that at least a portion of said NO contained in said exhaust gas is converted to NO2 at a temperature between about 175°
C. to 250°
C.; and
passing said NO2 through said particulate filter in an amount sufficient to oxidize particulate matter trapped on said filter. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
-
-
24. A method for treating diesel exhaust gases comprising:
-
positioning an oxidation catalyst in an exhaust gas passage of a diesel engine, said oxidation catalyst comprising platinum and a support material comprising zirconia-stabilized silica, said support material having strong acid sites;
providing a particulate filter in combination with said oxidation catalyst;
exposing said oxidation catalyst to diesel exhaust gas containing NO such that at least a portion of said NO contained in said exhaust gas is converted to NO2 at a temperature between about 175°
C. to 250°
C.; and
passing said NO2 through said particulate filter in an amount sufficient to oxidize particulate matter trapped on said filter.
-
-
25. A diesel exhaust gas treatment system comprising:
-
a particulate filter for receiving diesel exhaust gas from a diesel engine;
an oxidation catalyst for converting at least a portion of NO contained in said diesel exhaust gas to NO2 at a temperature between about 175°
C. to 250°
C., said oxidation catalyst comprising platinum and a support material comprising zirconia-silica, said support material having strong acid sites;
wherein said oxidation catalyst is impregnated in said particulate filter.
-
-
26. A diesel exhaust gas treatment system comprising:
-
a first oxidation catalyst for converting at least a portion of NO contained in said diesel exhaust gas to NO2 at a temperature of between about 175°
C. to 250°
C., said oxidation catalyst comprising platinum and a support material comprising zirconia-silica, said support material having strong acid sites; and
a second oxidation catalyst different from said first oxidation catalyst;
wherein said first and second oxidation catalyst are positioned in combination in the exhaust gas passage of a diesel engine.
-
Specification