Membrane operations for CO2 and CH4 separation

CO2 separation from flue gas coming out from a power plant or a cement industry, as well as CO2 from biogas and natural gas are some of the fields where membrane gas separation finds a large room of application, in particular with polymeric membranes. To this purpose, together with material science a fundamental role in the development of this technology on a scale different from lab one is covered by membrane engineering. Most of the studies related to the mass transport properties evaluation in literature are based on single gas permeation tests. However, a more detailed analysis of membrane performances not only in ideal conditions, but also feeding mixtures and in presence water vapour and other aggressive components, is one of the crucial assets for moving towards to real application. Thermally rearranged polymer membranes, mixed matrix membranes, ionic liquid membranes, etc. are some examples of membranes used for investigating these separations. Other aspects, such as aging effects owing to water vapour, physical compaction and thermal cycles and the effect of contaminants were and are currently under study, also with long term tests. Simulation studies assist experimental analysis for a unified evaluation of membrane unit operation. In this logic, general tools were developed in terms of performance maps suitable for analysing also membrane-integrated systems identifying proper operating conditions and proposing possible process schemes that can reach the targets for the various streams of interest.