Predictive models for permeability and diffusivity of CH4 through imidazolium-based supported ionic liquid membranes

► Two proposed models for predicting CH4 permeability and diffusivity through ILs. ► There is an acceptable agreement between models and experimental values. ► [hmim][Tf2N] shows high efficiency for gas permeability but low CO2/CH4 selectivity ► Higher gas permeabilities of [hmim][Tf2N] is due to low viscosity vs. [bmim][PF6]. ► Alumina supported [hmim][Tf2N] has higher selectivity vs. traditional polymer membrane.