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

Abstract

AbstractThis 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 (C3H6) and propane (C3H8) and their mixtures at 100 kPa‐700 kPa pressure and 298 K‐318 K temperature. Representative ILs were 1‐butyl‐3‐methylimidazolium thiocyanate ([C4mim]SCN) and 1‐ethyl‐3‐methylimidazolium thiocyanate ([C2mim]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 C3H6 shows a chemical absorption while C3H8 undergoes a physical one by [C4mim]SCN‐DMF‐CuSCN and [C2mim]SCN‐DMF‐CuSCN, and an increase in concentration of Cu + effectively improves the absorption capability for C3H6 and the selectivity of C3H6/C3H8. Furthermore, [C4mim]SCN‐DMF‐CuSCN had higher absorption capability and selectivity for C3H6 than [C2mim]SCN‐DMF‐CuSCN. [C4mim]SCN‐CuSCN‐2.0 M absorbed 0.637 mol of C3H6 per litre while 0.16 mol of C3H8 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 C3H6 and C3H8.