Spray-coating of nanoporous carbon membranes for air separation

Nanoporous carbons (NPC) can be fabricated in the form of supported thin fi lms with minimal defects and remarkably high size selectivity of oxygen ove r nitrogen. Spray coating of porous stainless steel disks with a solution o f poly(furfuryl) alcohol (PFA) in acetone was used to synthesize nanoporous carbon membranes in a reproducible manner, and is the first reported case of this technique being used for supported carbon membrane synthesis. The d isks were dried and then pyrolyzed in an inert atmosphere to a final temper ature of 600 degrees C. The resulting membranes were tested with binary oxy gen/nitrogen mixtures. In experiments with a binary feed of oxygen and nitr ogen, the membranes were found to have good oxygen over nitrogen selectivit ies (up to 4) and O-2 fluxes On the order of 10(-9) mol/m(2) sa. Attempts w ere made to modify membrane performance further by post-pyrolysis heating, additional coatings or by hydrocarbon pyrolysis. None of these post-treatme nts produced membranes superior to those derived directly from the initial spray coating and pyrolysis, (C) 1999 Elsevier Science B.V. All rights rese rved.