Robust core-shell ZIF-67@PDB-Br as synergetic catalyst for chemical fixation of CO2 without co-catalysts

Metal-organic frameworks (MOFs) are widely studied for cycloaddition of CO2 as a heterogeneous catalyst, because of their potential Lewis acidic sites and adjustable porous structure. However, most of them exhibit good catalytic performance need the assistance of nucleophilic co-catalysts. Herein, a novel MOFs and porous organic polymers (POPs) hybrid catalyst, core-shell ZIF-67@PDB-Br, is constructed by a convenient synthetic strategy, which possesses abundant Lewis acidic sites, imidazole cations and nucleophilic centers and shows robust chemical and thermal stability. This material demonstrates high-efficient catalytic activities and recyclability in the cycloaddition of CO2 and propylene oxide without co-catalysts, the conversion and selectivity can reach 94.1 % and 99.0 %, respectively (100 degrees C, 1.0 MPa CO2 pressure). Furthermore, the effects of the temperature, pressure, amount of catalyst and thickness of POPs shell on the catalytic activity were investigated. This study provides a viable direction for the development of synergistic heterogeneous catalysts for fixation of CO2 without co-catalysts.