Study on the Mechanism of Ni/γ-Al₂O₃ Catalyst Surface and Interface in the Dry Reforming of Methane

Dry reforming of methane (DRM) holds significant potential for converting greenhouse gases (CH₄ and CO₂) into synthesis gas. However, its application is severely limited by severe deactivation of Ni-based catalysts due to coking. This study systematically investigates the micromechanisms of the DRM reaction on Ni₉/γ-Al₂O₃(110) catalysts using density functional theory (DFT) calculations and microkinetic simulations. Results indicate that CH₄ dissociation preferentially occurs on the surface of Ni nanoparticles, while CO₂ activation and coke removal are dominated by the metal-support interface. The energy barrier for CO₂ hydrogenation at the interface is significantly lower than that for direct dissociation, and the key decarbonation step (C* + O* → CO) exhibits a markedly reduced barrier of 0.64 eV, effectively suppressing coke formation. Microkinetic simulations further reveal that CO is primarily generated via the CHO decomposition pathway, with the rate-determining step dynamically shifting from CO₂ hydrogenation to surface decarbonization as temperature increases. Additionally, negative external electric fields universally reduce energy barriers across key steps. This study elucidates the anticoking mechanism of Ni/γ-Al₂O₃ catalysts at the atomic scale, providing crucial theoretical foundations for rationally designing highly efficient and stable DRM catalysts.