A DFT+U study on the oxidative chlorination of CH4 at ceria: the role of HCl

The effects of HCl on the oxidation of CH4 at CeO2(111) have been studied by using density functional theory calculations corrected by on-site Coulomb interactions (DFT+U). The calculated results show that the presence of HCl barely affects the CH4 dissociation, but can provide new reaction channels to produce CH3Cl. The effects of surface defects and orientations on the surface reactivity were also considered. The total oxidation of CH4 can be partially prohibited by the high barriers for the further dissociation of CH3 at reduced surfaces due to the strong electronic repulsion of heavily accumulated localized electrons. CeO2(110) shows higher activity and selectivity for CH3Cl formation than CeO2(111), indicating that the morphologies of CeO2 nanocatalysts would be key to the catalytic activities toward CH4 activation.