(543c) Development of Carbon Molecular Sieve Membranes with Tunable Properties

Carbon molecular-sieve (CMS) membranes have been studied in the past few years as an alternative to both inorganic and polymeric membranes. They are known to have considerable resistance to high temperatures and pressures for gas separation applications, such as those involving gas mixtures containing H₂, CO₂, and CH₄. The preparation of the CMS membranes and the study of their transport properties have been investigated previously by our group and others. So far, tuning of the CMS membrane properties has primarily been performed through the selection of the polymeric precursors, and of the appropriate pyrolysis conditions. However, tuning based on such factors does not provide a generic solution for the membrane development for a wide range of industrial applications. In this study, we propose an alternative technique based on the post-treatment step in order to adjust the pore size of the CMS membrane, which is accomplished by activating the carbon surface using steam, which is a known technique used to prepare activated carbons with various pore structures. In our study we have investigated the influence of the various activation parameters, including the temperature and duration of the treatment on the properties of the resulting CMS membranes. We have also studied the modification of the surface affinity of such membranes through the incorporation of metal and solid oxide nanoparticles within the structure. The combined approach allows us to independently adjust the pore size and to modify the surface affinity. The transport and separation properties of the resulting CMS membranes are characterized in terms of their permeability and selectivity using single gases, such as H₂, CO₂, and CH₄, as well as by various other structure characterization techniques, including BET.