Synthesis and Characterization of Ionic Liquids with Metal Complex Anion and Its Capture to Carbon Dioxide

A series of ionic liquids with metal complex anion ［Bmim］［AXn+1］ were synthesized by one step method of mixing the same amount of imidazole ionic liquid ［Bmim］X(X=Cl, Ac) and inorganic salt AXn(A=Fe, Zn). The density and viscosity of the final products are measured at different temperatures. The correlations of density and viscosity with the temperature were obtained by empirical model. The solubilities of carbon dioxide in ［Bmim］X and ［Bmim］［AXn+1］ were measured. The results show that the density and viscosity of ［Bmim］X and ［Bmim］［AXn+1］ decrease with the increasing of temperature. Meanwhile, the density of ionic liquids with metal complex anion is much higher than that of the traditional ionic liquids. At the same time, the viscosities of ［Bmim］［ZnCl3］ and ［Bmim］［Zn(Ac)3］ are much higher than those of the conventional ILs ［Bmim］X. However, the viscosity of ［Bmim］［FeCl4］ is much lower than that of the ［Bmim］Cl. The ionic liquids with metal complex anion exhibit excellent ability in CO2 capture.