Oxidation catalyst

A catalysed soot filter comprising an extruded solid body in the wall-flow filter configuration consisting essentially of:

• 15-70% by weight of cordierite, nitrides, carbides, borides, intermetallics, lithium aluminosilicate, a spinel, an optionally doped alumina, titania, zirconia, titania-zirconia, zircon and mixtures of any two or more thereof;
• 0-20% by weight of a source of silica;
• 5-50% by weight of a zeolitic molecular sieve, a non-zeolitic molecular sieve or a mixture of any two or more thereof, each optionally containing one or more metal, wherein the zeolitic molecular sieve is a synthetic aluminosilicate zeolite and has a silica-to-alumina ratio of 10 to 150, and wherein the zeolitic molecular sieve is a medium pore molecular sieve, a large pore molecular sieve, or a meso pore molecular sieve;
• 20-80% by weight optionally stabilised ceria;
• and 0-20% by weight of inorganic fibres, which extruded solid catalyst body being coated with one or more layer(s) comprising supported at least one precious metal and combinations of any two or more precious metals.

A process for manufacturing an oxidation catalyst comprising the steps of:

• forming a solid extruded body by mixing powdered starting materials of:
• at least one binder/matrix component or a precursor of one or more thereof;
• zeolitic molecular sieve, non zeolitic molecular sieve or a mixture of any two or more thereof which zeolitic molecular sieve, non-zeolitic molecular sieve or mixture of zeolitic and non-zeolitic molecular sieves being optionally associated with at least one metal;
• an optional optionally stabilised ceria;
• and an optional at least one metal compound;
• with optional inorganic fibers;
• optionally adding an organic auxiliary agent;
• processing by mixing and/or kneading in an acid or alkaline aqueous solution optionally containing a metal salt of at least one metal into a plastic compound to form a mixture;
• extruding the mixture into a catalyst body, drying the catalyst body and calcining to form a solid extruded body;
• selecting quantitative proportions of the starting materials such that the solid extruded body comprises 10-95% by weight of at least one binder/matrix component;
• 5-90% by weight of a zeolitic molecular sieve, a non-zeolitic molecular sieve or a mixture of any two or more thereof, wherein the zeolitic molecular sieve is a synthetic aluminosilicate zeolite and has a silica-to-alumina ratio of 10 to 150, and wherein the zeolitic molecular sieve is a medium pore molecular sieve, a large pore molecular sieve, or a meso pore molecular sieve;
• and 0-80% by weight optionally stabilised ceria, and optionally at least one metal and impregnating a surface of the solid extruded body with at least one precious metal and/or coating a surface of the solid extruded body with at least one coating layer(s) containing at least one precious metal.