La 1− x C a x Co 1− y M g y O 3 nano‐perovskites as CO oxidation catalysts: Structural and catalytic properties

In this work, structural and catalytic properties of LaCo 1− y M g y O 3 and La 1− x C a x Co 0.50 Mg 0.50 O 3 nanocatalysts with x =0.00, 0.15, 0.30, 0.45, 0.60, 0.75 and y =0.00, 0.25, 0.50 prepared by citrate method are investigated. The structural characterization using X'Pert package and Fullprof program is an evidence for structural phase transition. The structural results suggest the presence of Co 4+ and Co 3+ ions that help to overall oxidation activity of these samples and this feature is higher for x =0.60. When substituting Mg and Ca in LaCoO 3 the catalytic activity of CO oxidation shifts to lower temperature. La 0.5 Ca 0.50 Co 0.5 Mg 0.5 O 3 nanocatalyst exhibits excellent CO conversion rate of 95% at 267°C. These results suggest that the lower temperature conversion of the sample x =0.60 in series of La 1− x C a x Co 1− y M g y O 3 can be mainly attributed to the presence of (i) higher Co 3+ –O–Co 4+ couples, (ii) a structure having the higher tolerance factor, and (iii) a lower crystallite size.