PREPARATION AND CATALYTIC ACTIVITY FOR ME THANE OXIDATION OF PEROVSKITE-TYPE LA(0.8)SR(0.2)MO(3) (M=CO, MN) WITH HIGH-SURFACE-AREA

Perovskite-type La(0.8)Sr(0.2)MO(3) (M = Co, Mn) compounds were prepar ed by malic acid-aided (MAL) and reverse homogeneous precipitation (RH P) methods and their catalytic activities for the total oxidation of m ethane were examined. Monophasic perovskites could be prepared by both methods at 823 K, which was lower by 300 K than the conventional nitr ate decomposition (NIT) method. The lowering of the calcination temper ature resulted in an increase in specific surface area. It appears tha t precursors with homogeneously dispersed constituent metal cations ar e formed by complexing metal cations with malic acid in the MAL method or by rapid and homogeneous precipitation as metal hydroxides in the RHP method, and therefore the formation of the perovskite phase at low er temperatures is facilitated. High surface-area oxides prepared by t he MAL and RHP methods showed higher catalytic activity for methane ox idation than oxides prepared by the NIT method, though promotion of we ight-normalized activity by the increased surface area was more promin ent in La0.8Sr0.2MnO3 than in La0.8Sr0.2CoO3. These results clearly in dicate that MAL and RHP methods are very useful for preparing highly a ctive perovskite catalysts.