Nonoxidative Coupling of Methane to Produce C₂ Hydrocarbons on FLPs of an Albite Surface

The characteristics of active sites on the surface of albite were theoretically analyzed by density functional theory, and the activation of the C-H bond of methane using an albite catalyst and the reaction mechanism of preparing C₂ hydrocarbons by nonoxidative coupling were studied. There are two frustrated Lewis pairs (FLPs) on the (001) and (010) surfaces of albite; they can dissociate H₂ under mild conditions and show high activity for the activation of methane C-H bonds. CH₄ molecules can undergo direct dissociative adsorption on the (010) surface, whereas a 50.07 kJ/mol activation barrier is needed on the (001) surface. The prepared albite catalyst has a double combination function of the (001) and (010) surfaces; these surfaces produce a spillover phenomenon in the process of CH₄ activation reactions, where CH₃ overflows from the (001) surface with CH₃ adsorbed on the (010) surface to achieve nonoxidative high efficiently C-C coupling with an activation energy of 18.51 kJ/mol. At the same time, this spillover phenomenon inhibits deep dehydrogenation, which is conducive to the selectivity of the C₂ hydrocarbons. The experimental results confirm that the selectivity of the C₂ hydrocarbons is maintained above 99% in the temperature range of 873 K to 1173 K.