Novel hydrazine-bridged covalent triazine polymer for CO2 capture and catalytic conversion

Abstract

Carbon dioxide (CO2) capture and catalytic conversion has become an attractive and challenging strategy for CO2 utilization since it is an abundant, inexpensive, and renewable C1 resource and a main greenhouse gas. Herein, a novel hydrazine-bridged covalent triazine polymer (HB-CTP) was first designed and synthesized through simple polymerization of cyanuric chloride with 2,4,6-trihydrazinyl-1,3,5-triazine. The resultant HB-CTP exhibited good CO2 capture capacity (8.2 wt%, 0 °C, and 0.1 MPa) as well as satisfactory recyclability after five consecutive adsorption-desorption cycles. Such a polymer was subsequently employed as a metal-free heterogeneous catalyst for the cyclo-addition of CO2 with various epoxides under mild and solvent-free conditions, affording cyclic carbonates with good to excellent yields (67%–99%) and high functional-group tolerance. The incorporation of hydrazine linkages into HB-CTP's architecture was suggested to play the key role in activating epoxides through hydrogen bonding. Moreover, HB-CTP can be reused at least five times without significant loss of its catalytic activity.