Patent ID: 6419890
Filing Date: 2002-07-16
Classification: B01D,B01J

Abstract:
A method for removing NOx and SOx contaminants from a gaseous stream comprising the steps of:(1) heat treating a catalyst precursor to form a catalyst composite; (2) in a sorbing period, passing a lean gaseous stream comprising NOx and SOx within a sorbing temperature range through the catalyst composite to sorb at least some of the SOx contaminants and thereby provide a SOx depleted gaseous stream exiting the catalyst composite and to sorb and abate at least some of the NOx contaminants in the gaseous stream and thereby provide a NOx depleted gaseous stream exiting the catalyst composite; (3) in a SOx desorbing period, converting the lean gaseous stream to a rich gaseous stream and raising the temperature of the gaseous stream to within a desorbing temperature range to thereby reduce and desorb at least some of the SOx contaminants from the catalyst composite and thereby provide a SOx enriched gaseous stream exiting the catalyst composite; and (4) in a NOx desorbing period, converting the lean gaseous stream to a rich gaseous stream to thereby reduce and desorb at least some of the NOx contaminants from the catalyst composite and thereby provide a NOx enriched gaseous stream exiting the catalyst composite; wherein the catalyst precursor comprises: (a) a platinum component; (b) a support; (c) a NOx sorbent component; and (d) a spinel material prepared by calcining an anionic clay material represented by the formula MmNn(OH)(2m+2n)Aa.bH2O, wherein M is Co2+; N is a trivalent metal cation; A is a mono-, di-, or trivalent anion which decomposes when heated to a temperature sufficient to form a volatile gas; m and n are such that m/n has values from about 0.5 to about 6; a is a number with the proviso that when A is a monovalent anion, a=n, when A is a divalent anion, a=Â½n, and when A is a trivalent anion, a=&frac13;n; and b is an integer having a value from 1 to about 10.