Molecular fence Cu-based catalyst for CO<sub>2</sub> hydrogenation to CO with high activity and durability.

Abstract

The conversion of CO₂ into high-value syngas (CO and H₂) using Cu-based catalysts has garnered considerable interest. However, these catalysts deactivate rapidly due to Ostwald-ripening and thermal aggregation. Herein, we propose to encapsulate Cu-cluster into mMOR zeolite for engineering a separation-site catalyst Cu@mMOR. In the reverse water-gas shift reaction (RWGS), mMOR zeolite of Cu@mMOR directly captures and then activates CO₂, and simultaneously serves as a molecular fence to prevent CO₂ contact with Cu-clusters surrounding with small pore of mMOR (<3.0 Å) channels. These encapsulated Cu-clusters in mMOR possess considerable Cu vacancies, which significantly facilitate H₂ heterolytic dissociation, transferring H^* species towards activated CO₂ on mMOR and converting them into CO. This separation-site strategy efficiently increases catalytic activation while intelligently altering the CO₂ reaction pathway, preventing Cu from thermal agglomeration and Oswald ripening in the catalyst. Consequently, Cu@mMOR attains a space-time yield of CO as high as 3290 mmol g_cat^-1 h^-1, with catalytic stability extending up to 788 hours.