Separation of propylene and propane by functional mixture of imidazolium thiocyanate ionic liquid-organic solvent-cuprous salt

This work presented the preparation of two new systems comprised of ionic liquids (ILs), organic solvent, and cuprous salt. Consequently, their absorption ability was investigated for propylene (C 3 H 6 ) and propane (C 3 H 8 ) and their mixtures at 100 kPa-700 kPa pressure and 298 K-318 K temperature. Representative ILs were 1-butyl-3-methylimidazolium thiocyanate ([C 4 mim]SCN) and 1-ethyl-3-methylimidazolium thiocyanate ([C 2 mim]SCN). N,N-dimethylformamide (DMF) and cuprous thiocyanate (CuSCN) were selected for the absorption system. The effects of operating parameters like Cu + concentration, pressure, temperature, and recycling of ILs absorbency were examined and compared with the literature. It was observed that C 3 H 6 shows a chemical absorption while C 3 H 8 undergoes a physical one by [C 4 mim]SCN-DMF-CuSCN and [C 2 mim]SCN-DMF-CuSCN, and an increase in concentration of Cu + effectively improves the absorption capability for C 3 H 6 and the selectivity of C 3 H 6 /C 3 H 8 . Furthermore, [C 4 mim]SCN-DMF-CuSCN had higher absorption capability and selectivity for C 3 H 6 than [C 2 mim]SCN-DMF-CuSCN. [C 4 mim]SCN-CuSCN-2.0 M absorbed 0.637 mol of C 3 H 6 per litre while 0.16 mol of C 3 H 8 per litre at 700 kPa and 298 K, with a selectivity of 3.9. This work shows that new combination of organic solvent and ILs with Cu + salt is a new class of potential reactive absorbents to separate C 3 H 6 and C 3 H 8 .