Method of treating diesel exhaust gases

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;
• 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;
• and
• passing said NO2 through said particulate filter in an amount sufficient to oxidize particulate matter trapped on said filter.

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;
• 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;
• and
• passing said NO2 through said particulate filter in an amount sufficient to oxidize particulate matter trapped on said filter.

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, said oxidation catalyst comprising platinum and a support material comprising zirconia-silica;
• 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.