Behaviour of 1-hexyl-3-methylimidazolium chloride-supported ionic liquid membranes in the permeation of CO2, H2, CO and N2 single and mixed gases

Abstract

The combined role of ionic liquids and membrane technology has demonstrated a tremendous potential in the field of gas separations; however, mostly single gas permeation data are available in literature and very few works report data regarding the membrane performance for the separation of gas mixtures. In this work, the performance of ionic liquid membranes prepared with the ionic liquid 1-hexyl-3-methylimidazolium chloride is assessed for the separation of binary, ternary and quaternary gas mixtures containing nitrogen, hydrogen, carbon monoxide and carbon dioxide. The mixed gas permeation properties of these gases are studied since they are the main components of flue gas generated after partial combustion of hydrocarbons. Therefore, the results obtained are compared to the pure gas permeabilities and ideal selectivities with especial interest on the effects on the recovery of H2 and CO, which are the most valuable gases of the mixture. In summary, a decrease in all gas permeabilities is observed when dealing with gas mixture feeds, particularly, for the most soluble gas CO2, due to a negative coupling effect. In contrast, the decrease in H2 permeability, the least soluble gas, is less marked, and therefore its recovery is favoured. In addition, the effect of temperature on the single gas permeability is evaluated between 303 and 323 K.