Patent ID: 7118722
Filing Date: 2006-10-10
Classification: B01D,B01J

Abstract:
1. A method for the reduction of nitrogen oxides with ammonia, which comprises: contacting a gaseous stream containing nitrogen oxides and ammonia at a temperature of from about 250° C. to 600° C. with a catalyst composition comprising: a metal-promoted aluminosilicate zeolite having improved stability formed by presteaming an aluminosilicate zeolite at a temperature of 600° C.˜800° C. for a period of time of 0.25 to 8 hours, said presteaming not providing significant dealumination of said aluminosilicate zeolite, adding metal to said presteamed zeolite, said zeolite having a silica to alumina mole ratio of at least about 8, and a pore structure which is interconnected in all three crystallographic dimensions by pores having an average kinetic pore diameter of at least about 7 Å.