Effects of strontium and copper substitution on the catalytic performance of LaCoO3 in the combustion of methane: an optimization study

Cobalt-based perovskites containing strontium and copper (La1-xSrxCo1-yCuyO3) were synthesized by the sol-gel method and characterized by XRD, H-2-TPR, N-2-adsorbtion, XRF and XPS techniques. The XRD results showed that the rhombohedral structure of perovskites was obtained. The activation energy employed to analyze the activities of samples in the combustion of methane was optimized using full factorial design (FD) by considering strontium (x=0, 0.1 and 0.2) and copper (y=0, 0.25 and 0.5) as the input variables. Analysis of Variance (ANOVA) was employed to investigate the obtained data and a p<0.05 was considered statistically significant. A second-order quadratic model was developed to calculate the activation energy on the basis of strontium and copper doping-degrees. FD results showed that perovskites containing strontium and copper in the range of 0.07-0.15 and of 0.2-0.4, respectively, had the best catalytic activity owing to the higher surface area, higher amounts of oxygen species, better reducibility and oxygen mobility.