The Synthesis Of Task-Specific Ionic Liquids And Using In Absorption And Separation CO₂

The room-temperature ionic liquids(RTILs) is a new type of green solvents which can be used in organic reactions, electrolyte materials, gas/liquid separation, especially in the absorption and separation of CO2. However, the absorption ability of conventional RTILs couldn’t meet the industrial requirements. And we can design the task-specific ionic liquids(TSILs) to achieve the effective absorption and separation CO2.However, the viscosity of RTILs limits its use. Membrane separation process has the advantage of low energy consumption, amplificationed easily. The combination of ionic liquids and membrane separation process, supported ionic liquid Membranes(SILMs) and poly(RTIL)-RTIL membranes, have potential advantages in the CO2separation.We synthesised NH2-functionalized ionic liquids and ether-functionalized ionic liquids for CO2absorption. The CO2absorption of former was in chemical way, while the latter was in physical way. And the ether- functionalized ionic liquids containing polymerizable vinyl group can form poly(RTIL)-RTIL membranes. We systematicly researched these TSILs in absorption and separation with SILMs and poly(RTIL)-RTIL membranes.We verified the structure of TSILs by the FT-IR and NMR analysis and the CO2absorption performance was evaluated under room temperature and atmospheric pressure. The ionic liquid could reused5times without significant loss of efficiency. The separation performance of SILMs and poly(RTIL)-RTIL membranes for CO2, CH4and N2was also determined. The ideal permeation selectivity of SILMs with TSILs for CO2/CH4and CO2/N2was much higher than that with [bmim][Tf2N]. With the transmembrane pressure increased, the gas permeation rate increased and the permeation selectively decreased. The poly(RTIL)-RTIL membranes was prepared with the ether-functionalized ionic liquids, AIBN,[bmim][Tf2N] and ethanol by the thermal-initiation polymerization. The effects of the crosslinking monomer concentration and the amount of [bmim][Tf2N] on the separation performance were evaluated. With the crosslinking monomer concentration increasing, the gas permeation rate decreased and permeation selectivity increased and then decreased. With the [bmim][Tf2N] content increasing, the gas permeation rate increased and then decreased and permeation selectivity gradually increased. Through the FT-IR, TGA, XRD analysis of poly(RTIL)-RTIL membranes, there was a polymer layer formed on the membrane surface, crystalline and amorphous regions presented in membrane and the membrane have well thermal stability.