Gas Separation by Supported Ionic Liquid Membranes

The use of ionic liquids (ILs) for gas separation processes recently has attracted much attention due to high solubilities of different gaseous species in ionic liquids [1]. The preparation of supported ionic liquid membranes (SILMs) is also reported for selective separation of different organic or gaseous compounds. Research activities have amongst others focused on CO2 separation from gas streams, representing a topic of world wide interest, the decrease of global warming causing gas emissions and, increasingly, the refinement of biogas for the feed-in of biologically produced methane into conventional natural gas distribution networks. Other interesting contaminants in many industrial gas streams are sulphur compounds. H2S as a toxic and corrosive substance is found nearly in all natural gas sources, synthesis gas and biogas streams. SO2 emissions are generated wherever fossil fuels are combusted. Other sulphur compounds, like tetrahydrothiophene (THT), are added to natural gas as odorants, making it impossible to be directly used in peripheral catalytic processes like home-based fuel cells for heat and electricity generation due to catalyst poisoning.