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US 2009/0155135 A1Published application
Catalyzed Soot Filter Manufacture and Systems
AssigneeBASF Catalysts LLC
InventorYuejin Li
Life of this patent
Estimating the term…
Abstract
Catalyzed soot filters comprising a wall flow monolith having microcracks and pores and a catalyst comprising support particles with particle sizes greater than about the size of the microcracks and less than about the size of the pores are disclosed. Methods of manufacturing catalyzed soot filters and diesel engine exhaust emission treatment systems are also disclosed.
Claims24
A catalyzed soot filter comprising:
- a wall flow monolith having a plurality of longitudinally extending passages formed by longitudinally extending walls bounding and defining said passages, the passages comprising inlet passages having an open inlet end and closed outlet end, and outlet passages having a closed inlet end and an open outlet end, the wall flow monolith including microcracks having an average width less than about 0.4 μm, and pores having a mean pore size in the range of about 10 μm to about 25 μm;
- and
- a washcoat disposed within the walls of the wall flow monolith, the washcoat including catalyst comprising support particles and at least one precious metal, where at least about 90% of the support particles have particle sizes greater than about the average size of the microcracks and at least about 90% of the support particles have particle sizes less than about the mean size of the pores of the wall flow monolith.
A method of making a catalyst-coated wall flow monolith containing microcracks having an average width less than about 0.4 μm and pores having a mean pore size in the range of about 10 μm to about 25 μm, the method comprising:
- providing a wall flow monolith having a plurality of longitudinally extending passages formed by longitudinally extending walls bounding and defining said passages, the passages comprising inlet passages having an open inlet end and closed outlet end, and outlet passages having a closed inlet end and an open outlet end and coating the wall flow monolith with a washcoat in the form of an aqueous slurry which contains a thermally decomposable catalytic material and solid particles, at least about 90% of the particles have a particle size greater than about the average size of the microcracks, and at least about 90% of the particles have a particle size less than about the mean size of the pores;
- and
- heating the coated wall flow monolith to a temperature sufficient to dry the washcoat.
Dependencies are inferred from the claim text.