Imidazolium With Cu(â… ) Salt Ionic Liquids For Separation Of Propylene And Propane

The separation of propylene and propane still relies on cryogenic separation distillation in industry, which needs high requirements for equipment, high cost, high energy consumption. Traditional solvents is organic solvents, which will cause solvent loss and environmental pollution, ionic liquids has low volatile and good solubility, thus ionic liquids are considered to be an ideal alternative to traditional organic separating agent. In addition, the transition metals have very good complexing absorption ability of olefins, and usually be used in the separation of olefin and paraffin with ionic liquids.In this paper, eight kinds of ionic liquids with different Cu+ concentration are designed and made, that are, [Bmim]SCN-CuSCN(OM, 0.5M,1.0M,1.5M), [Emim]SCN-CuSCN(OM,0.5M,1.0M,1.5M), which are used at 298 K,308 K,318 K,0-0.7 MPa to the absorption and separation of propylene and propane. Morever, Cu+ concentration, pressure, temperature, and the length of the ionic liquid cation also be investigated. The results show that the absorption of propylene and propane are increasing with the enhancing of Cu+ concentration, the length of the ionic liquid cation and pressure, decreasing with the enhancing of temperature. Under 298 K, with the moles of Cu+ concentration is 1.5, the absorption of propylene and propane reach maximum. The absorption of propylene/propane follows [Emim]SCN-CuSCN<[Bmim]SCN-CuSCN, while the selectivity follows [Bmim]SCN-CuSCN<[Emim]SCN-CuSCN.Ionic liquids are used for separation of propylene/propane mixture, with the moles fraction of propylene ranges from 50% to 80% at 298 K and 0.2-0.4 MPa. The results show that the selectivity of propylene/propane mixture is increasing with the enhancing of the Cu+ concentration and decreasing with the length of the ionic liquid cation. Gas mixtures with a higher mole fraction of propylene can reach higher absorption and selectivity. The selectivity of propylene/propane mixtures in [Bmim]SCN-CuSCN-1.5M is high up to 63.3 for 80 mol% propylene mixture with propane at 298 K and 0.2 Mpa.The ionic liquids are regenerated after r the absorption of propylene and propane. The absorption of propylene achieves after the regeneration of the solvent are similar to that obtained with the fresh solvent. The liquid mixture was used for more than 5 absorption and regeneration cycles without observable losses in the solvent efficiency, which means the ionic liquids are regenerative.