A composite membrane suitable for separating a gas from a gas mixture comprising a selective layer coated on a support, wherein said selective layer comprises: a) a polymeric matrix comprising an amine polymer; b) a graphene oxide nanofiller; and c) a mobile carrier selected from an ionic liquid or an amino acid salt.

The present invention refers to processes for the preparation of polymeric membranes, which can be nanostructured hybrids, containing ionic liquids and their derivatives for sequestration of CO.sub.2 from natural gas by gaseous permeation, and its referred membranes. The membranes of the present invention can be dense flat membranes, or composite asymmetric flat membranes. The invention can be applied in oil and gas extraction and renewable energies, for example, in existing gas treatment plants on off-shore platforms, replacing existing conventional polymeric membranes, as well as in new gas treatment plant designs that use polymeric membranes as natural gas purification technology, or treatment of exhausted gas streams.

Calcined or pyrolyzed metal compounds immobilized in membranes based on ionic liquids and/or eutectic solvents. The invention relates to new catalytic membranes synthesized from ionic liquids or deep eutectic solvents and oxidized or pyrolyzed immobilized metal compounds in the membranes. The use of these new catalytic membranes in oxidation/reduction reactions, for application in fuel cells and in water electrolyzers for hydrogen production, is described.

Described herein are gas separation membranes that provide improved compatibility between the gutter layer and the porous support and/or the separation layer for gases. Such composite membranes have a high water/air selectivity in permeability.