Core-Shell ZIF-67@CeO2 Nanosphere as Efficient Acid-Base Catalyst for the Cycloaddition of CO2 and Epoxides

摘要

Controllable deposition of nanosphere with zeolitic imidazolate frameworks (ZIFs) is an efficient method to achieve unique properties and create new types of multifunctional ZIF core-shell materials with enhanced properties. Core-shell ZIF-67@CeO2 nanosphere was designed with ZIF-67 nanoparticles as seed for the deposition of CeO2 nanocrystals. The as-prepared ZIF-67@CeO2 nanosphere can catalyze CO2 cyclo-addition reaction with significant activity. The synergistic acid-base catalytic sites of ZIF-67@CeO2 nanosphere were inves- tigated through TPD analysis. These sites can effectively coordinate and activate the substrate molecules, thereby enhancing catalytic efficiency for CO2 cycloaddition reaction. The ZIF-67@CeO2 nanosphere showed almost 100.00% conversion of styrene oxide and 100.00% selectivity of desired cyclic carbonate (120°C, 7.5 bar, and 8 h). In addition, ZIF-67@CeO2 showed a negligible decrease in the catalytic activity even after being reused for four cycles.