Mechanisms of Heterogeneous Processes in the System SiO_2 + CH_4: I. Methane Chemisorption on a Reactive Silica Surface

摘要

Experimental and quantum chemical study of reactive silica surface methylation is carried out. The main product of the reaction is the (≡Si–O)_2Si(H)(CH_3) groups, which are formed via a radical-chain process with the participation of methane molecules and paramagnetic and diamagnetic defects on the oxide surface. Spectral (optical and IR) characteristics of the groups participating in the process (≡Si–O)_2Si~·–CH_3, (≡Si–O)_2Si(H)(CH_3), and (≡Si–O)_2Si(CH_3)(CH_3) are determined. Information on the kinetics of separate steps of the process is obtained including rate constants and the activation energies of steps.