Catalytic Dehydrogenation of Ethane over Doped Perovskite via the Mars-van Krevelen Mechanism

For effective utilization of ethane in natural gas, catalytic dehydrogenation of ethane is a promising option that offers better efficiency than ethane cracking to produce ethylene, the most important fundamental chemical. Recently, it was reported that catalytic dehydrogenation of ethane proceeds effectively on doped perovskite oxide via the Mars-van Krevelen (MvK) mechanism. For this work, the reaction mechanism was investigated using density functional theory calculations. Results demonstrated that ethane activation over perovskite (La1-xBaxMnO3-delta) proceeds at the surface lattice oxygen coordinated with Ba, resulting in a low energy barrier of the C-H bond activation. Based on Bader charge analysis, the electron-deficient surface lattice oxygen, which is favorable for hydrogen abstraction from light alkanes, forms around Ba. In addition, the electronic charges of the surface lattice oxygen are important for H-2 desorption. The electronic charge depends on hydrogen coverage: electron-rich surface lattice oxygen, which is favorable for H-2 desorption, forms at high hydrogen coverage. Therefore, a part of the surface lattice oxygens of perovskite would be covered with hydrogen atoms under the reaction atmosphere, leading to effective H-2 desorption and the proceeding catalytic cycle via the MvK mechanism.