Improved Catalytic Activity and Stability of Ba Substituted SrTiO3 Perovskite for Oxidative Coupling of Methane

Perovskite oxides are widely used as the catalyst for oxidative coupling of methane (OCM). The partial substitution of A or B sites in ABO(3) perovskites with heteroatoms was effective in improving the catalytic performance, but the promoting mechanism has not been thoroughly studied. In this work, the partial substitution of Sr with Ba in SrTiO3 perovskite was demonstrated to improve both the OCM reaction activity and stability. Compared with SrTiO3 and BaTiO3, the crystal size of Ba0.5Sr0.5TiO3 was greatly reduced (similar to 55 nm), the amount of surface chemisorbed oxygen species acting as the alkaline active centers for OCM was increased, and the electrophilic lattice oxygens with higher electronegativity rapidly replenishing the surface alkaline active sites were obtained. Thereby, a higher C-2 yield (similar to 18 %) and C2H4/C2H6 ratio (similar to 1.7) were simultaneously achieved. Furthermore, the enhanced reaction stability was attributed to the better thermal resistance of nano-sized Ba0.5Sr0.5TiO3 perovskite.

Automated summary

The partial substitution of Sr with Ba in SrTiO3 perovskite was shown to enhance the catalytic performance, with improved activity and stability in OCM reaction. This improvement was mainly attributed to the reduced crystal size, increased surface chemisorbed oxygen species, and better thermal resistance of nano-sized Ba0.5Sr0.5TiO3 perovskite.