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

Abstract

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 °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.