Patent ID: 7563423

Claim:
In a method for removing nitrogen oxides from an exhaust gas stream, wherein the exhaust gas stream is contacted with a SOx removal catalyst which reduces the content of sulfur oxides in the exhaust gas stream and wherein the exhaust gas is thereafter contacted with a NOx reducing catalyst which converts nitrogen oxides to NO 2 which is sorbed by the NOx reducing catalyst, the SOx removal catalyst and NOx reducing catalyst housed within a reactor compartment, the improvement comprising the steps of: (a) isolating the reactor compartment from the flow of the exhaust gas stream; (b) directing a regeneration gas into the isolated reactor compartment for a time effective to regenerate sorbency of the NOx reducing catalyst; (c) after regenerating the sorbency of the NOx reducing catalyst, then directing the regeneration gas into the isolated reactor compartment for a time effective to regenerate sorbency of the SOx removal catalyst; (d) introducing a sulfur removal gas into the reactor compartment after step (c), but prior to step (e), wherein the sulfur removal gas is introduced for a time effective to reduce an amount of sulfur in the SOx removal catalyst; and (e) thereafter recommencing the flow of the exhaust gas stream through the reactor compartment.