“…The purification of natural gas and landfill gas, and the biogas upgrading 2 through the separation of CO 2 from the CO 2 /CH 4 mixtures, a process that improves their energy content, have acquired great relevance in the last years. A large variety of technologies and sorbents are being actively investigated 3,4 to improve the efficiency of more conventional sorbents based on zeolites and activated carbons. Among them, membrane-based technologies [5][6][7] offer many advantages, since they are easy to implement, scalable and energy efficient.…”