Patent ID: 7669408
Filing Date: 2010-03-02
Classification: F01N,F02D,Y02A,Y02T

Abstract:
1. A method of desulfating a LNT, comprising: injecting a reductant into an exhaust flow over a period of desulfating the LNT; passing the reductant through a first device, wherein the reductant reacts with oxygen in the exhaust to consume a substantial portion of the oxygen in the exhaust; and passing the exhaust through the LNT; wherein the injection of reductant is intermittent on two different time scales, one longer and one shorter; intermittent in the case of each time scale comprising cycling between periods over which there is substantially no reductant injection and periods over which there is substantial reductant injection; and the periods on the longer time scale being on average at least about four times longer than the corresponding periods on the shorter time scale.