Process to progressively heat a NOx catalytic converter to sulfur removal temperature by stepped alternating fuel-rich and lean-burn phases

摘要

In a process to heat an automotive NOx storage catalytic converter, the motor is alternately operated in fuel-rich ((F) and lean-burn ((m) modes. Also claimed is an automobile with a commensurate fuel mixture regulating system in which the switch from lean burn to rich burn takes place in a series of stepped phases. The NOx catalytic converter is heated prior to the onset of a de-sulfurization process. The NOx catalytic converter is directly preceded by a pre-catalyst that is generally devoid of oxygen.