(659b) Development of Carbon Molecular-Sieve Membranes with Tunable Properties

Carbon molecular sieve (CMS) membranes are known as good candidates in gas separation applications, such as those that involve the CO₂/CH₄ gas pair, with considerable resistance to high temperatures. The preparation of CMS membranes and the study of their transport properties have been fully investigated previously by our group and others. However, so far, tuning of the CMS membrane properties has primarily been performed by the proper selection of the polymeric precursors, and of the appropriate pyrolysis conditions. However, tuning based on such factors does not provide a general, solution for the membrane development for a wide range of industrial applications. To fully exploit the versatile features of CMS membranes, our approach in this study is to independently adjust the pore size and to modify the surface affinity, which is accomplished by activating the membrane carbon surface using steam and methane, and by introducing metal and solid oxide nanoparticles within the membrane structure. In our experiment study, so far, nickel-formate, nickel acetylacetonate, and palladium acetylacetonate were chosen as the metal precursors for the preparation of metal-impregnated CMS membranes. This is due to the fact that they self-decompose to nickel/palladium nanoparticles at elevated temperatures, and the strong affinity of these metals towards H₂. Several techniques have been utilized to incorporate the metal nanoparticles within the CMS membranes. 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. Experimental data for the permeation characteristics of these membranes, and the effect of the various preparation conditions will be presented at the meeting. We intend to use these membranes in three model applications that involve CO₂ capture and sequestration in the context of power generation. They include CO₂ separation from flue-gas (post-combustion capture), H₂ separation from reformate and water gas shift mixtures (pre-combustion capture), and O₂/N₂ separations (oxy-fuel combustion).