基于DFT的LaNiO3载氧体上化学链蒸汽甲烷重整反应机理研究OA

Chemical looping-steam methane reforming(CL-SMR)enables efficient methane conversion to clean energy,with LaNiO3 emerging as a promising oxygen carrier due to its exceptional oxygen storage capacity and catalytic activity.However,the micro mechanism of CH4 conversion on LaNiO3 surface remains unclear,which limits the directional optimization design of LaNiO3 oxygen carrier.To clarify the reaction mechanism of CL-SMR on LaNiO3(110)surface,based on density functional theory(DFT),adsorption models of various intermediates(CHx,x=0～4)on LaNiO3(110)surface during CH4 decomposition were first constructed to clarify the stable adsorption configuration.Then the micro reaction path network was analyzed from four core processes:CH4 sequential dehydrogenation,CO/CO2 formation,H2/H2O generation and oxygen diffusion.The results show that during the CH4 sequential dehydrogenation process on LaNiO3(110)surface,there are strong interactions between the intermediates and the oxygen carrier surface,and the adsorption configurations are stable.The process is thermodynamically favorable and the reaction paths are stable and feasible.Among them,the energy barrier required for the CH dehydrogenation is significantly higher than other steps,identified as the rate-determining step.Generated CO readily oxidizes further to CO2,while H prefer forming H2O.What's more,the oxygen vacancies formed after the consumption of surface oxygen by the reaction can be supplemented by the bulk lattice oxygen diffusion.LaNiO3 oxygen carrier can efficiently catalyze CH4 conversion to CO2 and H2O,but its catalytic performance needs to be further improved by lowering the energy barrier of rate-determining step.This relevant research results clarify the reaction mechanism of CH4 on LaNiO3(110)surface,in order to provide a theoretical reference for designing high-performance LaNiO3 oxygen carriers for CL-SMR.