The influence of SO42- on the catalytic combustion of soot using O2 and NO/O2 mixtures over Na-promoted Al2O3 catalysts

NO(g) increases conversion of soot to COx. Surface SO42- has no effect on activity for the C(s) + O2 reaction but decreases activity in the Carbon + NO/O2 oxidation. This is interpreted in terms of SO42- blocking NO adsorption sites, thus poisoning the NO + O2 → NO2 reaction, which is essential for the NOx promoted oxidation.