In the last years membrane processes for gas separation are gaining a larger acceptance in industry and in the market are competing with consolidated operations such as pressure swing absorption and cryogenic distillation.The key for new applications of membranes in challenging and harsh environments (e.g., petrochemistry) is the development of new tough, high performance materials. The modular nature of membrane operations is intrinsically fit for process intensification, and this versatility might be a decisive factor to impose membrane processes in most gas separation fields, in a similar way as today membranes represent the main technology for water treatment. This review highlights the most promising areas of research in gas separation, by considering the materials for membranes, the industrial applications of membrane gas separations, and finally the opportunities for the integration of membrane gas separation units in hybrid systems for the intensification of processes.

The intrinsic characteristics of a membrane process, i.e. efficiency and operational simplicity, high selectivity and permeability for the transport of specific components, compatibility between different membrane operations in integrated systems, low energetic requirements, easy control and scale-up, and high operational flexibility, might be decisive factors in imposing membrane processes in most gas separation fields. This review highlights the research hardware in membrane gas separation, i.e. the membrane material. Emphasis has been devoted to three interesting and important membrane classes for gas separation: block copolymer membranes, carbon membranes and mixed matrix membranes.

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