Evaluation of oxygen vacancy and carbon deposition effect at the perovskite on methane adsorption

Abstract

The perovskite with A-site doping can improve the reactivity of oxygen carrier and fuel so as to promote the performance of chemical looping hydrogen production (CLH). In this study, the effects of Sr doping in the A site of LaFeO3 perovskites on the adsorption of CH4, CH3, CH2 and CH are investigated and the oxidation reaction process on the perovskite surface is measured by means of the quantum chemistry calculation. The formation of oxygen vacancy and carbon deposition on the perovskite surface with A-site doping is evaluated. The results demonstrate that the increase of oxygen vacancy content can promote the charge transfer between the perovskite surface and CH4, CH3 and CH2. Whereas the formation of oxygen vacancy weakens the CH oxidation ability so as to reduce the adsorption energy of CH. Meanwhile, the carbon deposition does not only affect the charge transfer on the perovskite surface, but also alters the adsorption mode. The Sr doping lowers the energy barrier for the CH oxidation reaction, while the formation of carbon deposits makes the oxidation of CH difficult.