Molecular Simulation On Ionic Liquids’ CO₂ Adsorption And Research Of Ionic Liquids Polyer

Since the industrial revolution, due to the increasing of the CO₂ emissions, the greenhouse effect is more and more serious. The ionic liquids, known as a kind of solvent for absorption of CO₂, have the characteristics of negligible vapor pressure, adjustable structure, high viscosity. Compared to organic solvent, they are hard to volatilize, non-toxic and have a long use life. In the field of CO₂ adsorption, they have a broad application prospect.But the number of kinds of ionic liquids is very large. If we use them in experiment, the cost of synthesis is high. About the influence of microstructure to CO₂ adsorption, we didn’t have a clear understanding because of the lack of systematic theory. It is hard to choose a fit ionic liquid to absorb CO₂ by experiment. With the progress of computer calculation technology, more and more fields appear the applications of molecule simulation method. It’s a very appropriate way to screen ionic liquids and research their propertys by molecular simulation method.We combine the Molecular Dynamic Simulation（MD） method and Monte Carlo Simulation（MC） method, draw the mole fraction isotherm of CO₂ in ionic liquids. Open source software LAMMPS is used in the MD simulations, open source software TOWHEE is used in the MC simulations. Because of the compact structure of ILs, the Monte Carlo Simulation is hard to reach the thermodynamic equilibrium. A method of segmented disturbance is used in this paper, and get a faster equilibrium process. The simulations of CO₂ solubility in 1-n-hexyl-3-methylimidazoliumbis（trifluoromethylsulfonyl） imide（[hmim] [Tf₂N]） at different temperatures and pressures in a wide range are performed.Because of the match force field, the simulation results are in good agree with the experiment, indicating the molecular simulation can be used at the quantitative forecast about the ILs’thermodynamic property. Different cations and different anions are used to analyse their effect on CO₂ solubility. The simulation result shows that the length of alkyl chain on the cation can effect the solubility, longer chain will get higher CO₂ solubility. About the anion, CF3- on the anion will increase the CO₂ solubility, especially CF3-. The research of CH₄ and N₂ solubility in [hmim][Tf₂N] shows that their solubilities are an order of magnitude lower than CO₂. The mixtures of CH₄/CO₂ and N₂/CO₂ dissolution behavior in [hmim][Tf₂N] are also researched, with different mixing ratio. The result shows the selectivity of CO₂ decreases with the increase of CO₂ mixing ratio and pressure.In addition, a brief introduction of the next work, about the ionic liquids polymer, was written here.