Synthesis Of Functional Ionic Liquids And Characteristics Of CO₂ Capture

CO₂ is one of the most important greenhouse gases, most of the CO₂ emissions come from the power plant. How to caputure CO₂ from flus gas is one of important research points. Ionic liquids have a lot of excellent characteristics, such as low vapor pressure, low meiling point, high dissolution and adjustable structures, using ionic liquid to fix CO₂ has become one of the key research directions in CO₂ emission reduction. Meanwhile, Imidazolium ionic liquids are studied frequently by many researchers now.Accroding to different experiment proposal, several imidazolium ionic liquids were synthesized by two-step metheod, including traditional imidazolium ionic liquids [bmim]BF₄, [emim]BF₄ and functional ionic liquids [Cl-OH-b-mim]COOH. We characterize the structures of these ionic liquids by IR and 1HNMR, and investigate the influential factors that should be noticed during the experiment.The CO₂ absorption performances of synthesized ionic liquids have been discussed at normal temperature and pressure, the CO₂ adsorption capacity, adsorption equilibrium time have been obtained, [bmim]BF₄ has the highest CO₂ solubilities which is 0.076 mol(CO₂)/mol(IL), and the adsorption equilibrium time of [emim]BF₄ is shortest. The CO₂ desorption experiment have been carried out after CO₂ absorption process to analyze the performances of ionic liquids desorption.Accroding to the research above, several ionic liquids have been modified by–OH and–NH₂, functional ionic liquids that including–OH([OH-e-mim]Br) and–NH₂ ([NH₂P-mim]Br,[NH₂-e-mim]BF₄)in the imidazolium alkyl chains have been synthesized. Experimental results show that the CO₂ adsorption capacity and adsorption equilibrium time of modified ionic liquids have been improved remarkably, the CO₂ solubilities of [OH-e-mim]Br and [NH₂-e-mim]BF₄ is 2 and 3.5 times than that of [emim]BF₄. In addition, the impaction of water, temperature, pressure on the adsorption performances and desorption characteristics have been studied. Experimental results show that functional ionic liquids [NH₂-P-mim]Br which including–NH₂ group in the imidazolium alkyl chains has the biggest adsorption capacity, which is kind of potential functional ionic liquids.