Effects of Manganese substituted Lithium or Magnesium of SrMnO3 perovskite on Light off Temperature of CO and Hydrocarbon Oxidation

Catalysts with the formula of SrAxMn(1-x)O(3-δ), where x is 0.0, 0.1, 0.2, 0.3, and A is Li or Mg were studied for CO and C2H6 oxidation in a synthetic exhaust gas of gasoline engines. A 6.0%CO and 0.2%C2H6 in Ar mixed with stoichiometric amount of air was used as the synthetic exhaust gas, emitted by internal combustion engines. Ethane was selected as a model for unberned hydrocarbons in the exhaust gas. The catalysts were prepared by combustion–like method and calcined at 850 and 1000oC for 5 h, respectively. SrMn(1-x)O(3-δ) perovskite structure is observed in XRD patterns of studied catalysts. Manganese oxide peaks of the reductions are observed in range of 305–750oC. The peak at>750oC is observed in SrAxMn(1-x)O(3-δ) catalysts, which is absent in pure manganese oxide, is related to strontium oxide. XRD and TPR analysis are evidence for the formation of a nonstoicheometric SrMn<1O3–δ perovskite. The rest of manganese oxide is observed to disperse on perovskite structure, affecting its properties.

Keywords:

Mixed oxides , Nonstoicheometric Perovskite , SrMnO3 , Mn3O4 , CO , Hydrocarbon , exhaust gas , catalyticconverter , Oxidation