Investigation on sulphation and regeneration of a commercial monolithic NOx-storage/reduction catalyst

Sulphur poisoning and regeneration of a commercial NSR catalyst by SO2 were investigated in dependence on temperature and λ value. The amount of desorbed sulphur compounds during lean-rich regeneration cycles was found to increase with decreasing λ value (0.99-0.94) at constant temperature and with increasing temperature (660-720 °C) at constant λ value. At a regeneration temperature of 660 °C, removed sulphur components comprises mainly SO2 at λ values near 1, whereas H2S and COS are released at lower λ values. At higher regeneration temperatures and low λ values more SO2 is released, but COS and H2S formation also increases.