Catalyst for the reduction of nitrogen oxides and method for the production thereof

Claim 1

A catalyst for the reduction of nitrogen oxides obtained by calcining at least one particulate iron hydroxide at a temperature not exceeding 550° C and coating the calcined particles with an aqueous solution of an aluminum salt, washing, drying and molding the particles having the aluminum salt coating, followed by baking to form an alumina coating, said catalyst containing 60 to 90 percent by weight of Fe 2 O 3 and 40 to 10 percent by weight of Al 2 O 3 and having an average pore diameter of not more than 500 A, a pore volume of not less than 0.1 cc/g and a specific surface area of not less than 10 m 2 /g.

Claim 8

A method for the production of a catalyst for the reduction of nitrogen oxides, which method comprises: (a) calcining at least one iron hydroxide at a temperature not exceeding 550° C; (b) pulverizing the resultant calcined material to a size of not more than 100μ; (c) introducing 0.1 to 1 parts by weight of the thus pulverized material, while agitating into 1 to 10 parts by weight of an aqueous solution containing 5 to 80% by weight of an aluminum salt and subsequently neutralizing the solution thereby causing precipitation of the aluminum salt present in said mixture; (d) ageing the neutralized mixture, thereby coating the surface of said calcined material with said aluminum salt; (e) separating the coated calcined material obtained in step (d), washing and drying the coated material and molding the coated material to suitable shape; and (f) subsequently baking the calcined material thus coated with the aluminum salt at a temperature in the range of from 300° to 1200° C.

Claim 9

A method for the production of a catalyst for the reduction of nitrogen oxides, which method comprises: (a) calcining at least one iron hydroxide at a temperature not exceeding 550° C; (b) pulverizing the resultant calcined material to a size of not more than 100μ; (c) introducing 0.1 to 1 parts by weight of the thus pulverized material, while agitating into 1 to 10 parts by weight of an aqueous solution containing 5 to 80% by weight of an aluminum salt and subsequently neutralizing the solution thereby causing precipitation of the aluminum salt present in said mixture; (d) ageing the neutralized mixture, thereby coating the surface of said calcined material with said aluminum salt; (e) separating the coated calcined material obtained in step (d), washing and drying the coated material and molding the coated material to suitable shape; and (f) subsequently baking the calcined material thus coated with the aluminum salt at a temperature in the range of from 300° to 1200° C.