La1−xCaxCo1−yMgyO3 nano‐perovskites as CO oxidation catalysts: Structural and catalytic properties

In this work, structural and catalytic properties of LaCo_1?yMg_yO₃ and La_1?xCa_xCo_0.50Mg_0.50O₃ 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 Co⁴⁺ and Co³⁺ 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 LaCoO₃ the catalytic activity of CO oxidation shifts to lower temperature. La_0.5Ca_0.50Co_0.5Mg_0.5O₃ 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?xCa_xCo_1?yMg_yO₃ can be mainly attributed to the presence of (i) higher Co³⁺–O–Co⁴⁺ couples, (ii) a structure having the higher tolerance factor, and (iii) a lower crystallite size.