Catalytic properties of novel La–Sr–Cu–O–S perovskites for automotive C3H6/CO oxidation in the presence of SOx

A La–Sr–Cu–O–S system with K2NiF4 perovskite-type structure has been studied as a novel SOx-resistant combustion catalyst. The XRD result implied that sulfur is incorporated into the structure as non-sulfate-type cations. An introduction of sulfur with highly positive valence (S6+ or S4+) into the lattice requires the charge compensation by decreasing the oxidation number of Cu. This is accompanied by the creation of more reducible Cu species, which would achieve the light-off of catalytic C3H6 oxidation at lower temperatures. More important feature of sulfur-containing compounds is that the catalytic C3H6 oxidation was significantly accelerated by addition of SO2 to the gas feed. The catalytic performance for the oxidation of C3H6 and CO and the reduction of NO was finally evaluated in a simulated automotive exhaust in the presence of SO2.