DFT investigation of active sites in metal-doped ferrierite zeolites for selective methane oxidation to methanol

Abstract

Metal-doped ferrierite (FER) zeolites demonstrate excellent catalytic potential for the direct conversion of methane to methanol. In this study, density functional theory (DFT) calculations were employed to systematically investigate the reaction pathways and catalytic performance of active sites in metal-doped FER zeolites (M = Fe, Co, Ni, Cu). Theoretical analysis reveals that the C–H bond activation mechanism strongly depends on the electronic structure of the central metal, and metals with partially filled d-orbitals (Fe, Co, and Ni) tend to follow a concerted proton-electron transfer (CPET) pathway, whereas copper (Cu) with a fully occupied d¹⁰ configuration favors a hydrogen atom transfer (HAT) mechanism. Notably, the [CuO]⁺ active site, owing to its distinct electronic structure, exhibits both strong oxygen radical character and remarkable electron-withdrawing capability, leading to the highest reactivity in methane C–H bond activation. This work elucidates the structure–activity relationships of metal-doped zeolite active sites at the atomic and electronic levels, provides key theoretical insights into the core reaction mechanism, and offers valuable guidance for designing a new generation of highly efficient zeolite-based catalysts for the selective oxidation of methane to methanol.