Composite-alumina-carbon molecular sieve membranes prepared from novolac resin and boehmite. Part I: Preparation, characterization and gas permeation studies

摘要

Supported composite alumina-carbon molecular sieve membranes (c-CMSM) were prepared\udfrom in house prepared novolac phenolic resin loaded with boehmite nanoparticles\udin a single dipping-drying-carbonization step. A porous a-alumina tube support was dipped\udinto a N-methyl-2-pyrrolidone solution containing polymerized novolac resin loaded with\udboehmite, subsequently dried at 100 C and carbonized at 500 C under nitrogen environment.\udThe structure, morphology and performance of the membranes were examined by\udscanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis\ud(TGA), carbon dioxide adsorption and permeation of N2, O2, He, H2 and CO2. SEM showed\udcarbon membranes with a thin and very uniform layer with a thickness of ca. 3 mm CO2\udadsorption isotherms indicated that the produced carbon membranes presented a microporous\udstructure. The c-CMSM exhibited good gas separation properties. The permselectivity\udsurpass the Robeson upper bound for polymeric membranes, especially regarding\udideal permselectivities of pairs H2/N2 ¼ 117, and He/O2 ¼ 49. Aging effects were observed\udafter membrane exposure to ambient air. However with a thermal treatment under nitrogen\udatmosphere the permeance of nitrogen increases.