Membranes Membranes Exploring the Gas-Permeation Properties of Proton-Conducting Membranes Based on Protic Imidazolium Ionic Liquids: Application in Natural Gas Processing Kallem P. Charmette C. Drobek M. Julbe A. Mallada R. Universidad de Zaragoza Pina M.P. Universidad de Zaragoza 2018 research-article