Highly Durable NOx Reduction System and Catalysts for NOx Storage Reduction System

NOx storage-reduction catalysts have shown serious deactivation in the presence of SOx. This is because, under lean conditions, SOx adsorbs more strongly on NO₂ adsorption sites than NO₂, and the adsorbed SOx does not desorb altogether even under rich conditions. We have solved the problem by configuring, in front of the NOx storage-reduction catalysts, SOx adsorbents that can adsorb only SOx among SOx and NOx in exhaust gases under the lean conditions and desorb the adsorbed SOx easily under the rich conditions. The catalysts can reduce NOx, CO and hydrocarbons at a high rate for a prolonged period.