Porous bi-functional ionic liquid-grafted metal–organic framework for diluted CO2 cycloaddition reaction

Abstract

Direct utilization of low-concentration CO2 is of importance to mitigate the global warming and reduce energy consumption. Herein, a new bi-functional ionic liquid-grafted material was fabricated for CO2/N2 selectivity and diluted CO2 cycloaddition reaction. Following the preparation of 1-carboxymethyl-3-methoxy ethyl-imidazolium chloride ([CmMOEim]Cl) containing carboxyl and ether group, MIL-53(Al) was used for directly chemical grafting of the ionic liquid to obtain [CmMOEim]Cl@MIL-53(Al). CO2 capture capacity of [CmMOEim]Cl@MIL-53(Al) reached up to 70 cm3 CO2/g sorbent at 25 °C and 0.1 MPa, which was higher than that of two individual components. Cyclopropyl carbonate of 97 % yield was obtained at 110 °C, 3 MPa of initial 50 vol% CO2/N2 pressure and 4 h with 2.4 wt% [CmMOEim]Cl@MIL-53(Al)-0.4 under solventless and co-catalyst-free condition. Various terminal cyclocarbonates were synthesized with above 90 % yield. In addition, the heterogeneous catalyst was separated from reaction system by simple centrifugation and the yield of cyclopropyl carbonate was higher than 90 % after 12 cycles owing to the chemical grafting of [CmMOEim]Cl on MIL-53(Al).