B-Doped and NH₂-functionalized SBA-15 with hydrogen bond donor groups for effective catalysis of CO₂cycloaddition to epoxides

Until recently, many metal-based catalysts have been developed for the cycloaddition reaction of CO2 with epoxides. However, the leaching of the active metal component would lead to various environmental problems. A novel nonmetal B-doped Lewis acid-base catalyst with hydrogen bond donor (HBD) groups (B-SBA-15-NH2) was prepared successfully through the hydrothermal process and post-modification. B-SBA-15-NH2 exhibited good catalytic performance for the CO2 cycloaddition reaction, and 95% yield of propylene carbonate and satisfied selectivity (98%) were achieved in the presence of the KI cocatalyst. The efficient catalytic activity of B-SBA-15-NH2 resulted from the synergistic effects of B and HBD groups, together with the functionalized -NH2 groups. B-SBA-15-NH2 also exhibited good generality with acceptable yields for the corresponding cyclic carbonates in the CO2 cycloaddition with various epoxides. Furthermore, the developed B-SBA-15-NH2 catalyst could be easily separated by centrifugation and reused for five runs without an obvious loss in activity. The good activity and stable reusability of the metal-free B-SBA-15-NH2 catalyst demonstrate that it is a promising green candidate catalyst in the field of CO2 conversion.