Vacancy-Anchored Sub-Nanometer Ru Catalyst with High Activity and Strong Durability at 800 °C Dry Reforming of Methane

Abstract

Dry reforming of methane (DRM) represents an important way to convert both CO₂ and CH₄ to reduce greenhouse effects and produce valuable chemical products. Owing to the strong bonding energies of both CO₂ and CH₄ molecules, DRM usually proceeds at a high temperature, which inevitably causes catalyst sintering, leading to catalyst deactivation. This work develops a highly stable sub-nanometer Ru catalyst on a Ni-doped MgO support using Mg²⁺ vacancies as anchors. The optimized Ru_1.5/Ni₁-MgO-R catalyst displays 90% CH₄ conversion and 92% CO₂ conversion to syngas in DRM at 800 °C. More importantly, it exhibits strong durability and can run continuously for more than 1200 h. Both the characterizations and the density functional theory (DFT) calculations demonstrate that the Ni²⁺ substituted Mg²⁺ in the MgO matrix produces Mg²⁺ vacancies (Mg_V), which can stabilize sub-nanometer Ru clusters of ≈0.9 nm. Moreover, the presence of Mg_v-Ru₈ clusters strongly stabilizes sub-nanometer Ru. This study contributes valuable insights into the design of sub-nanometer metal catalysts with strong sintering resistance at high temperatures.