Diesel particulate filter

A method for producing a filter comprising spraying a dry particulate aerosol onto an inlet surface of a porous filter for filtering particulate matter from a lean-burn exhaust gas, to form a filter cake having a density of 0.3 to 1.2 g/in3, wherein said aerosol comprises inorganic particles selected from the group consisting of silicate zeolite, aluminosilicate zeolite, metal-substituted aluminosilicate zeolite, non-zeolitic molecular sieve, and metal oxide, provided that said metal oxide particles have an average size of greater than 0.2 μm and less than 5 μm,

• wherein the filter comprises:
• (a) a porous substrate having an inlet surface and an outlet surface, wherein the inlet surface and the outlet surface are separated by a porous structure;
• and (b) a catalytic filter cake in the form of a bridge network on the inlet surface, said bridge network comprising interconnected inorganic particles selected from the group consisting of silicate zeolite, aluminosilicate zeolite, metal-substituted aluminosilicate zeolite, non-zeolitic molecular sieve, and metal oxide, provided that said metal oxide particles have an average size of greater than 0.2 μm and less than 5 μm, where the interconnected inorganic particles are dry aerosol deposited, the particles form a bridge over the pores.