Method for the preparation of a catalysed particulate filter and catalysed particulate filter
First Claim
1. Method for the preparation of a catalysed particulate filter comprising the steps ofa) providing a particulate filter body with longitudinal flow passages being confined by longitudinal porous walls, defining a dispersion side and a permeation side;
- b) providing a first catalyst washcoat containing a first catalyst composition being active in selective catalytic reduction of nitrogen oxides,c) providing a second catalyst washcoat containing a second combined catalyst composition in form of a mixture of a catalyst being active in selective oxidation of ammonia to nitrogen, and a catalyst being active in oxidation of carbon monoxide and hydrocarbons;
d) coating the particulate filter body with the first catalyst washcoat on the entire dispersion side and within partition walls of the filter body, and coating the particulate filter with the second catalyst washcoat on the entire permeate side of the filter body; and
e) drying and heat treating the coated filter to obtain the catalysed particulate filter.
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Abstract
The invention pertains to a catalyzed particulate filter provided in its entire dispersion side and within its partition walls with a first catalyst being active in selective catalytic reduction of nitrogen oxides, and in its entire permeate side with a second catalyst combination with a catalyst being active in oxidation of ammonia mixed with a catalyst being active in oxidation of carbon monoxide and hydrocarbons and a method for its preparation. The mean particle size of the first catalyst is smaller than the mean pore diameter of the longitudinal porous walls, and the mean particle size of the second catalyst combination is larger than the mean pore diameter of the longitudinal walls. In the example, the first catalyst is a silica aluminum phosphate SAPO-34 promoted with 2% copper and the second catalyst is a mixture of platinum and palladium (molar ratio 3:1) supported on alumina particles and beta zeolite powder with 1.0% copper.
7 Citations
9 Claims
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1. Method for the preparation of a catalysed particulate filter comprising the steps of
a) providing a particulate filter body with longitudinal flow passages being confined by longitudinal porous walls, defining a dispersion side and a permeation side; -
b) providing a first catalyst washcoat containing a first catalyst composition being active in selective catalytic reduction of nitrogen oxides, c) providing a second catalyst washcoat containing a second combined catalyst composition in form of a mixture of a catalyst being active in selective oxidation of ammonia to nitrogen, and a catalyst being active in oxidation of carbon monoxide and hydrocarbons; d) coating the particulate filter body with the first catalyst washcoat on the entire dispersion side and within partition walls of the filter body, and coating the particulate filter with the second catalyst washcoat on the entire permeate side of the filter body; and e) drying and heat treating the coated filter to obtain the catalysed particulate filter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification