US 9,810,118 B2
Catalyst system for the reduction of NOx and NH3 emissions
Haren Sakarai Gandhi, West Bloomfield, MI (US); John Vito Cavataio, Dearborn, MI (US); Robert Henry Hammerle, Franklin, MI (US); and Yisun Cheng, Ann Arbor, MI (US)
Assigned to Ford Global Technologies, LLC, Dearborn, MI (US)
Filed by Haren Sakarai Gandhi, West Bloomfield, MI (US); John Vito Cavataio, Dearborn, MI (US); Robert Henry Hammerle, Franklin, MI (US); and Yisun Cheng, Ann Arbor, MI (US)
Filed on Sep. 8, 2010, as Appl. No. 12/877,901.
Application 12/877,901 is a continuation of application No. 12/706,558, filed on Feb. 16, 2010, abandoned.
Application 12/706,558 is a continuation of application No. 12/325,787, filed on Dec. 1, 2008, granted, now 7,674,743.
Application 12/325,787 is a continuation of application No. 11/684,064, filed on Mar. 9, 2007, granted, now 7,485,273.
Application 11/684,064 is a continuation of application No. 10/065,470, filed on Oct. 22, 2002, granted, now 7,332,135.
Prior Publication US 2011/0005200 A1, Jan. 13, 2011
Int. Cl. B01D 53/94 (2006.01); F01N 3/08 (2006.01); F01N 3/18 (2006.01); F01N 3/20 (2006.01); B01D 53/86 (2006.01); F01N 3/10 (2006.01); F01N 13/00 (2010.01)
CPC F01N 3/0814 (2013.01) [B01D 53/8631 (2013.01); F01N 3/0842 (2013.01); F01N 3/108 (2013.01); F01N 13/0097 (2014.06); F01N 2240/25 (2013.01); F01N 2510/06 (2013.01); Y02C 20/10 (2013.01); Y02T 10/22 (2013.01); Y02T 10/24 (2013.01)] 11 Claims
OG exemplary drawing
 
1. A method for reducing pollutants in the exhaust gas of an engine having a system including a nitrogen oxide adsorber and a NH3-SCR catalyst downstream of the nitrogen oxide adsorber, comprising the steps of:
supplying the nitrogen oxide adsorber with exhaust gas while the engine operates under lean conditions, wherein the exhaust gas is in a lean exhaust gas;
transitioning the engine operations from lean to rich conditions;
supplying the nitrogen oxide adsorber with exhaust gas during said transitioning;
minimizing the oxygen content of the nitrogen oxide adsorber prior to rich conditions to facilitate the reduction of NOx to NH3;
completing the transition from lean to rich conditions; and
supplying the nitrogen oxide adsorber with exhaust gas while the engine operates under rich conditions, wherein the exhaust gas is a rich exhaust gas.