Properties of La1−x Ce x CoO3 system perovskite-type catalysts for diesel engine exhaust removal

Abstract

A series of complex oxide La1−x Ce x CoO3 catalysts was synthesized at a low temperature through a combustion process, in which x is among 0, 0.1, 0.2, 0.4 and 0.6 corresponding to the quantity of La3+ partial substitution by Ce4+. The catalysts were characterized for phase composition using chemical analysis and X-ray diffraction. The catalytic activity of the catalysts in removal of NO x , total hydrocarbon (THC) and particulate matter (PM) from diesel exhaust gases were examined in detail using temperature-programmed reaction technique. The results show that after partial substitution of La3+ with Ce4+, the oxygen vacancy concentration increases significantly and a Co3+-Co2+ system is formed. Consequently, the catalytic activity in the removal of THC and NO x is significantly improved. But for the PM, the effect is not so obvious. The possible catalytic mechanism for this was presented. It is also worth noting that the doped catalysts showed good stability.