Preparation Of Polymeric Ionic Liquid Catalyst And Its Application In Synthesis Of Dimethyl Carbonate

Dimethyl carbonate（DMC）is an important organic chemical with low toxicity and good environmental friendliness,so it is widely used in industry.It is a colorless and transparent liquid,which can be mixed with many organic compounds at room temperature and has good solubility and stability.Dimethyl carbonate can be used to synthesize high value-added chemicals,such as polycarbonate,polyurethane,polyimide,etc.,and can also be used as solvents,cleaning agents,fuel additives,etc.In addition,dimethyl carbonate can also be used as an alternative in green chemical synthesis to replace toxic and harmful organic solvents and reactants.A novel spherical polymerized ionic liquid solid base catalyst（PILs-FL）was prepared by suspension polymerization and applied to the synthesis of dimethyl carbonate by transesterification.The catalyst was characterized by FT-IR,TG,BET and SEM.The yield of propylene carbonate was 98.2%,the selectivity of cycloaddition reaction was100%,the reaction temperature was 80°C,the pressure was 1.0MPa,the amount of catalyst was 2.0wt%,and the activity did not decrease after repeated use for 5 times.No polymer was found,indicating that the catalyst can be used for the addition of CO₂and propylene oxide to synthesize propylene carbonate.Dimethyl carbonate was synthesized by transesterification.A novel spherical polymeric ionic liquid solid base catalyst（PILs-FL）was prepared.The catalysts were characterized by scanning electron microscopy（SEM）,specific surface area measurement（BET）,Fourier transform infrared spectroscopy（FT-IR）,Hammett indicator benzene carboxylic acid titration,elemental analysis（EDS）and thermogravimetric analysis（TGA）.The catalytic performance was evaluated by transesterification of ethylene carbonate with methanol.The results showed that the optimal reaction conditions were as follows:the molar ratio of methanol/ethylene carbonate was 9:1,the amount of catalyst was 3 wt%,and the reaction was carried out at 90°C for 5 hours.Under the optimal conditions,the yield of DMC could reach 93.7%.The repeated experiments showed that the catalytic activity did not decrease significantly after repeated 5 times.The reaction was studied in detail in a fixed bed reactor,and the yield of dimethyl carbonate reached 83.4%.A novel spherical polymer catalyst（PILs-XSS）was prepared by one-pot synthesis of dimethyl carbonate from CO₂,methanol and propylene oxide.The catalysts were characterized by scanning electron microscopy（SEM）,specific surface area measurement（BET）,Fourier transform infrared（FT-IR）,elemental analysis（EDS）and thermogravimetric analysis（TGA）.The catalytic performance of the catalyst was evaluated in a one-pot reaction.The optimum reaction conditions were as follows:the amount of PILs-XSS catalyst was 2.5wt%,the pressure of CO₂was 1.5MPa,the reaction temperature was 100°C,the reaction time was 4h,the molar ratio of methanol to PO was3:1,and the amount of Na₂CO₃was 3wt%.Under the optimum conditions,the conversion of propylene oxide（PO）reached 98.8%and the yield of DMC reached 53.7%.After repeated use for 5 times,the catalytic activity was not significantly reduced.