Highly efficient capture and conversion of CO2 into cyclic carbonates from actual flue gas under atmospheric pressure

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Chemical conversion of CO2 to cyclic carbonates is one of the most attractive strategies for CO2 capture and storage utilization. Herein, a binary organocatalyst of 3-aminobenzylalcohol/n-Bu4NI was used to gently catalyze the insertion of CO2 into the terminal/internal epoxides to generate cyclic carbonates under metal-free and solvent-free conditions. Twelve representative terminal epoxides reacted with CO2 to achieve excellent cyclic carbonate yields of up to 98.3 % at 30 °C and 1 atm CO2 and six low activity internal di-substituted epoxides were converted to corresponding cyclic carbonates with yields of up to 96.2 %. Experiments on actual flue gas and water resistance revealed the potential industrial value of this binary organocatalyst. The yield of cyclic carbonate reached 99 % by using actual flue gas under very mild conditions of 60 °C and 1 atm. The results of 4-fold epoxide amplification experiment showed that the residual CO2 in the flue gas was only 793 ppm after reaction at 1 atm and 60 °C, indicating the good CO2 capture and conversion ability. Reaction kinetics and catalytic mechanism of the cycloaddition were investigated in detail. The synergistic effect among functional groups of catalysts on substrates is the essential factor for the high activity of the catalyst.