文摘
As environmentally friendly and designable solvents, ionic liquids (ILs) have great potential in the separation of C2H4 and C2H2, which is quite important in chemical industry. The microscopic insight into the intermolecular interaction and the diffusion dynamics at a molecular level is crucial for designing more efficient ILs. In this work, the interaction mechanism and diffusion dynamics for C2H4/C2H2 absorption and separation with five ILs, 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]), 1-butyl-3-methylimidazolium acetate ([bmim][OAc]), 1-butyl-3-methylimidazolium trifluoroacetate ([bmim][TFA]), 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([bmim][Tf2N]), and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([bmpyrr][Tf2N]), were investigated by molecular dynamics (MD) simulation. The result suggests that the van der Waals interaction between C2H4 and cation plays an important role in C2H4 dissolution in ILs, but the hydrogen bonding interaction between C2H2 and anion is foremost in C2H2 dissolution. Moreover, the interaction energy analysis matches better with the experimental solubility than our previous quantum chemical calculation, indicating the superiority of the MD simulation approach in studying the interaction mechanism of IL-based systems where multiple interactions are often present. The self-diffusion coefficients of cations and anions of ILs do not change obviously after adding C2H4, while they have a significant increase after dissolving C2H2, particularly in relatively strong hydrogen bonding systems [bmim][OAc]鈥揅2H2.