Potential of Silver-Based Room-Temperature Ionic Liquids for Ethylene/Ethane Separation

The potential of room-temperature ionic liquids (RTILs) in separating ethylene from ethane is investigated. The absorption of olefins is enhanced by chemical absorption via pi-complex formation with a transition-metal cation added to a standard RTIL. The effects of the ionic liquid structure of silver-based RTILs that contain Ag(I) salts (AgNO(3), Ag[TfO], and Ag[Tf(2)N]) on gas absorption and solvent stability are investigated. The absorption isotherms of C(2)H(4) and C(2)H(6) into Standard RTILs and designed silver-based RTILs were measured with a gravimetric balance between 303 and 333 K and up to 10 bar. C(2)H(4) absorption was chemically enhanced in the silver-based RTILs and was considerably higher than that in the standard RTILs. Absorption of C(2)H(6) in the silver-based RTILs is based on physical interactions only. The olefin/paraffin selectivity at a pressure of I bar was similar to 30-50 higher in the silver-based RTILs than in standard ionic liquids.