A density functional theory study of CH4 oxidation over LaMnO3 oxygen carrier during chemical looping combustion

LaMnO 3 -based oxygen carriers (OCs) are considered a promising class of materials for chemical looping combustion (CLC); however, elucidating their detailed microscopic reaction mechanisms remains challenging. In this study, density functional theory (DFT) calculations were employed to investigate the reaction mechanisms of CH 4 combustion on the LaMnO 3 (010) surface. The results reveal that CH 4 weakly adsorbs with negligible charge transfer, whereas CH x species (x = 0–3) exhibit strong chemisorption, which strengthens as hydrogen atoms are removed. The CH → C + H step is identified as the rate-limiting step during CH 4 dehydrogenation, featuring an energy barrier of 2.233 eV. For CO 2 formation, the adsorbed carbon atom (C*) reacts first with O 1 (the first lattice oxygen atom) to form CO*, which then reacts with O 2 (the second lattice oxygen atom) to produce CO 2 *, followed by desorption, with an overall energy barrier of 1.693 eV. H 2 O formation occurs via surface hydrogen reacting with lattice O 1 , forming H 2 O* at the O v1 (the vacancy formed by O 1 removal) site prior to desorption, with an energy barrier of 1.465 eV. Overall, CH 4 dehydrogenation governs the reaction kinetics, while surface oxygen is critical for enabling complete oxidation to CO 2 and H 2 O. This study provides fundamental insights into CH 4 oxidation on LaMnO 3 (010), which may guide the design of novel OCs in the future. • DFT investigation of CH 4 oxidation on LaMnO 3 (010) during chemical looping. • CH → C + H is the rate determining step for CH 4 oxidation with highest energy of 2.233 eV. • H 2 O formation is energetically more favourable than CO 2 formation.