Highly efficient synergistic CO2 conversion with epoxide using copper polyhedron-based MOFs with Lewis acid and base sites

Abstract

To systematically study the effect of Lewis acid sites (LASs) and Lewis base sites (LBSs) in MOF materials for the CO₂ cycloaddition reaction, four isomorphous copper polyhedron-based MOFs (Cu-PMOFs), JLU-Liu20, JLU-Liu21, JLU-Liu22 and JLU-Liu46 with different amounts of LASs and LBSs were selected to investigate their CO₂ fixation catalytic performance. It is commendable that the catalytic capabilities of the four Cu-PMOFs exceed that of most reported MOF-based catalysts. Benefitting from the abundant LASs and appropriate alkaline strength of LBSs, JLU-Liu21 shows the best catalytic performance for the cycloaddition of CO₂ with epoxides among the four Cu-PMOFs and the yield of catalyzing propylene oxide can reach up to 98% under 1 bar CO₂. It is worth mentioning that even under post-combustion flue atmosphere (15% CO₂ and 85% N₂), its yield can reach up to 92%, which surpasses most other MOF catalysts under similar reaction conditions. The 5-time recycling circulation experiments also indicated JLU-Liu21's excellent recyclability and catalytic stability, which is highly desirable in decontaminating noxious gas and meets industrial requirements for sustainability.