Pushing the limits on possibilities for large scale gas separation: which strategies?

Opportunities abound to extend membrane markets for gas and vapor separatio ns; however, the existing membrane materials, membrane structures and forma tion processes are inadequate to fully exploit these opportunities. The req uirements for viability of membranes vary somewhat with each application. N evertheless, the key requirements of durability, productivity and separatio n efficiency must be balanced against cost in all cases. The various 'conte nder' technologies for large scale gas separation membrane applications and the gas transport mechanisms are considered. The current spectrum of appli cations of gas separation membranes include; nitrogen enrichment, oxygen en richment, hydrogen recovery, acid gas (CO2,H2S) removal from natural gas an d dehydration of air and natural gas. The current status and the limitation s faced by the available membrane materials for each of these applications are discussed. Two key technical challenges exist. Achieving higher permsel ectivity for the relevant application with at least equivalent productivity is the first of these challenges. Maintaining these properties in the pres ence of complex and aggressive feeds is the second challenge. Attractive av enues to overcome these challenges for each application will be presented. Finally, several new membrane applications with immense potential (e.g. fue l cells and olefin-paraffin separations) an discussed.