Influence of exhaust gas components on the regeneration of catalytic ceramic filters for soot removal

The influence of exhaust gas components on the combustion of soot over unsulfated and sulfated catalytic filters was studied. The catalyst is deactivated by the presence of sulfur oxides in the exhaust gases, but it is able to regain most of its activity when it is employed in more realistic operating conditions. Indeed, with both unsulfated and sulfated catalytic filters, the presence of either NO or H2O resulted in substantial increases in the rate of carbon combustion. The improvement in the soot catalytic oxidation rate in the presence of NO can be attributed to carbon oxidation by NO2, which is, in turn, produced by NO oxidation on the catalyst. Instead, in the presence of H2O, the observed enhancement could be due to the catalytic activation of the steam gasification of carbon on the same catalyst.