CARBON MOLECULAR-SIEVE GAS SEPARATION MEMBRANES .2. REGENERATION FOLLOWING ORGANIC-EXPOSURE

Carbon molecular sieving (CMS) membranes have been found to have excep tional gas separation properties with high-purity feeds. The basic nat ure of the carbon itself, however, makes these membranes vulnerable to compounds typically found in industrial process streams. Because of t heir organophilic nature, CMS materials are excellent adsorbents for o rganics, and this results in significant problems in membrane applicat ions. The studies detailed in this paper show that CMS membranes are v ulnerable to adverse effects from exposure to organic contaminants. Me mbrane performance losses were severe, and occurred with feed stream c oncentrations of organics as low as 0.1 ppm. The pattern was consisten t and observed for a number of different organic compounds. For variou s reasons, regeneration techniques used for carbon adsorbents were not suitable for the CMS membranes. However, a very promising regeneratio n process has been identified that uses pure propylene at unit or near -unit activity as a cleaning agent. This property appears to be unique to propylene, and may have significant implications for a number of a pplication areas.