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

Carbon molecular sieving (CMS) membranes have been found to have exceptional gas separation properties with high-purity feeds. The basic nature of the carbon itself, however, makes these membranes vulnerable to compounds typically found in industrial process streams. Because of their organophilic nature, CMS materials are excellent adsorbents for organics, and this results in significant problems in membrane applications. The studies detailed in this paper show that CMS membranes are vulnerable to adverse effects from exposure to organic contaminants. Membrane performance losses were severe, and occurred with feed stream concentrations of organics as low as 0.1 ppm. The pattern was consistent and observed for a number of different organic compounds. For various reasons, regeneration techniques used for carbon adsorbents were not suitable for the CMS membranes. However, a very promising regeneration 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 application areas.