Application Of New Ionic Liquid Catalyst In Synthesis Of Cyclic Carbonate

Carbon dioxide（CO₂） is one of the main culprits of global climate change.Its excessive emissions may cause a"greenhouse effect"and have a devastating impact on the environment and ecosystems.The level of carbon dioxide in the atmosphere is close to the concentration of 400 ppm.Due to the development of industry and economic growth,especially in developing countries,this number will increase in the next few years.Controlling and curbing carbon dioxide emissions is one of the great challenges in recent decades,at least before all carbon-based energy is replaced by renewable energy.Therefore,the development of carbon capture and utilization technology with available and valuable chemical products is considered as a feasible way to deal with excessive carbon dioxide in the atmosphere.Due to the cheap,rich,renewable and non-toxic characteristics of carbon dioxide,the capture and fixation of carbon dioxide in high-value-added chemicals have attracted widespread public attention.Due to the inherent thermodynamic stability and kinetic inertia of carbon dioxide molecules,it is an extremely urgent task to design efficient catalysts,especially environmentally friendly heterogeneous catalysts.In recent years,the catalysis of carbon dioxide to the substrate,such as epoxide to form cyclic carbonate or polycarbonate,has attracted widespread attention.It is one of the most promising methods to produce five-membered cyclic carbonate by coupling epoxide and carbon dioxide with 100%atomic efficiency.Cyclic carbonate products and their derivatives are widely used as polar and non-protonic solvents with high boiling points,and are the main precursors for the synthesis of polymer materials and fine chemical intermediates.In order to catalyze the synthesis of cyclic carbonates from carbon dioxide and reduce the use of halogens,a more environmentally friendly and recyclable catalyst is designed.We synthesized four amino-functionalized ionic liquids and polymerized the ionic liquids with DVB to obtain polyionic liquid catalysts.The functional groups and chemical bonds of four amino-functionalized ionic liquids were investigated by infrared spectroscopy（IR）.The microstructure of the polymer was observed by scanning electron microscopy（SEM）.The structural composition of the polymer was determined by XPS.The decomposition temperature of the catalyst was determined by thermogravimetry.We studied the effects of temperature,pressure,catalyst dosage and reaction time on the cycloaddition reaction of carbon dioxide by using the control variable method.In this experiment,epichlorohydrin was used as the substrate.The experimental results showed that when the amount of catalyst was 0.15 g,the reaction pressure was 0.5 MPa,the reaction temperature was 100℃,and the reaction time was 10 hours,the yield of chloropropylene carbonate reached 97.8%.At the same time,we demonstrated good repeatability through cyclic experimental results.The above results show that the new polyionic liquid catalyst can catalyze the synthesis of cyclic carbonate from carbon dioxide under mild conditions without solvent and cocatalyst.At the end of this article,starting from the molecular and electronic levels,the monomer structure of the synthesized polyionic liquid catalyst is studied.Structural optimization,frequency calculation,and HOMO and LUMO orbital analysis were conducted to compare catalysts with higher affinity for catalytic reaction monomers,resulting in better catalytic performance in catalytic reactions.