Patent ID: 7743602

Claim:
An apparatus for catalytically processing a gas stream passing therethrough to reduce the presence of NO x therein, said apparatus comprising: a combination catalyst having first and second catalysts positioned in a staged arrangement for catalytically processing the gas stream, said combination catalyst including: a first catalyst for catalytically processing the gas stream being selected from the group consisting of metal-containing alumina, metal oxide-containing alumina, or a combination thereof, wherein the metal is selected from the group consisting of silver, indium, gallium, tin and cobalt and mixtures thereof, said first catalyst having a first temperature at which peak catalytic activity occurs, said first catalyst being adapted for both converting a portion of NO x directly to N 2 and another portion to nitrogen-containing intermediates with a portion of NO x remaining; and a second catalyst being located downstream from the first catalyst for catalytically processing the gas stream subsequent to the first catalyst, said second catalyst being selected from the group consisting of a metal-containing zeolite, metal oxide-containing zeolite, or a combination thereof, wherein the metal is selected from the group consisting of copper, iron, cobalt, and silver and mixtures thereof, said second catalyst having a second temperature at which peak activity occurs, said second catalyst being adapted to facilitate the reaction of the remaining NO x and intermediates for further reduction into N 2 , wherein the value of the second temperature is lower than the value of the first temperature; a source of reductant for injection of reductant into said gas stream upstream of said combination catalyst, said reductant being a hydrocarbon compound; an activator selected from the group consisting of hydrogen (H 2 ), oxygenated hydrocarbon, or a combination thereof, for injection thereof upstream of said combination catalyst, for activating said reductant to improve low temperature NO x conversion; and a reformer for providing said activator by converting a portion of said hydrocarbon from said source of reductant into at least one of H 2 and oxygenated hydrocarbon.