Application of silver ionic liquid in the separation of olefin and alkane

Abstract

AbstractBACKGROUNDThe separation of olefins and alkanes remains one of the most challenging industrial processes due to their similar structure and boiling points. Traditional industrial methods are limited as a consequence of high equipment cost and energy consumption. Ionic liquids (ILs) for olefin separation systems have been developed in recent years. This study aimed to synthesize silver (Ag+) IL and apply it in both extraction and membrane processes to enhance the separation performance.RESULTSQuantum chemical calculation results show that the interaction energy between the IL and cyclohexene is much larger than the values for interactions between the IL and alkanes. The highest selectivities for cyclohexene in the extraction process were 33.4 and 51.9 in the presence of cyclohexane and hexane, respectively. The gel membrane was prepared by casting a mixture of 12HSA and Ag+ IL solution onto the PVDF membrane. In vapor permeation, high separation performance was obtained together with a stable membrane phase when the 12HSA content was 1.50% and the operating temperature was 45 °C. With the increase of the mole fraction of cyclohexene, the permeation flux gradually increased and the separation factor was maintained at >9.CONCLUSIONReversible π‐complex formation between Ag+ ions and cyclohexene can effectively enhance the separation performance in both extraction and membrane process. This study presents a promising alternative to conventional technology for olefin and alkane separations. © 2021 Society of Chemical Industry (SCI).