Research For Synthesis Of Diethyl Carbonate From Carbon Dioxide,Ethanol By Basic Ionic Liquids

Diethyl carbonate?DEC?is a green organic carbonate,which has been widely used in organic chemicals,synthetic drugs,electronic engineering and energy fields.Basic ionic liquids?BILs?as an environmentally-friendly green reaction solvent and new type of catalytic materials,both with high activity of traditional liquid alkaline and easy separation of solid base.Therefore,the study of direct synthesis of DEC catalyzed by BILs has important theoretical and practical value.Two type of new basic ionic liquids choline hydroxide?CH?and choline methoxy?CMe?were synthesized by functional design.And their structures of ionic liquids were characterized by FT-IR and 1HNMR.The basicity of BILs were analyzed by UV-Hammett in order to find the relationships between the baiscity of BILs and their catalytic activity.The synthesis of DEC by CMe or CH from carbon dioxide and ethanol was studied in this work.The results indicated that CMe showed higher catalytic activity in the reaction,and the effects of various reaction conditions were investigated with the single-factor tests.The optimal reaction conditions for the reaction were obtained: reaction temperature 150 ?,reaction time 4 h,CO₂ initial pressure 5.0MPa,ethanol 20 ml,and the amount of the ionic liquids 2.0 g,the yield of DEC is 0.52%.In addition,the macroscopic kinetic constants of the reaction for the direct synthesis of DEC were measured.Then the kinetic models were established,and the frequency factors,activation energy,and the reaction rate equations of reaction were also determined.Furthermore,a possible mechanism of the reaction was proposed on the basis ofexperimental results.Ea⁺=75.742 k J?mol^-1,A⁺=113.103,A^-=6.41?10⁷,Ea^-=40.056 k J?mol^-1.