Patent ID: 8381512
Filing Date: 2013-02-26
Classification: B01D,F01N,F02D,H04L,Y02T

Abstract:
1. A method for reducing NOx emissions in an exhaust gas feedstream output from an internal combustion engine, the method comprising: equipping the engine with an exhaust aftertreatment system including a catalytic device fluidly serially connected upstream of an ammonia-selective catalytic reduction device, the ammonia-selective catalytic reduction device including catalytic material comprising a base metal; monitoring a temperature of the ammonia-selective catalytic reduction device; forbidding operation of the engine at a lean of stoichiometry air/fuel ratio and a rich of stoichiometry air/fuel ratio when a temperature of the ammonia-selective catalytic reduction device is not within a predetermined operating range defined by a lower temperature limit and an upper temperature limit; only when the temperature of the ammonia-selective catalytic reduction device is within the predetermined operating range defined by the lower temperature limit and the upper temperature limit, modulating the engine to generate an engine-out exhaust gas feedstream including nitric oxide, carbon monoxide, and hydrogen that converts to ammonia on the catalytic device, wherein modulating the engine comprises operating the engine at one of a stoichiometric air/fuel ratio and a rich of stoichiometry air/fuel ratio; storing the ammonia on the ammonia-selective catalytic reduction device; and reducing NOx emissions in the exhaust gas feedstream in the ammonia-selective catalytic reduction device using the stored ammonia.