Tunable Polyimide and Resulting Carbon Molecular Sieve Membranes for Gas Separation

摘要

Polymer membranes have been used for natural gas and olefin-paraffin gases separations successfully. However, the separation performance is limited by a productivity and efficiency trade-off upper bound. Therefore, advanced carbon molecular sieves (CMS) materials were developed. These materials show separation performance that exceeds the polymer "upper bound" for gas separations, while potentially maintaining economically attractive manufacturing. CMS membranes can be formed by thermal decomposition of polymer precursors, and contain "micropores" of 6-20 A connected by smaller so-called "ultramicropores". The combination of ultramicropores and micropores provides the molecular sieving function and high permeability characteristics of these unusual CMS membranes.