A novel precursor for the sol gel and CVD methods to prepare alumina permselective membranes

Abstract

A novel metalorganic compound, Al(OPri)(2)(etac), was synthesized and used for the preparation of alumina permselective membranes. Membranes were produced by forming permselective thin layers on porous alumina support tubes, either by dip-coating of alumina sol, by the chemical vapour deposition (CVD) technique, or by a combination of the two. In CVD processing, a commercial precursor, Al(OPri)(3) was also studied and compared with our novel precursor. Characterization of alumina-producing materials was performed by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis/differential thermal analysis and H-1-nuclear magnetic resonance. The gas separation performance of alumina permselective membranes was measured by permeation experiment using hydrogen and nitrogen gases. For each membrane, gas permeation rates and H-2/N-2 selectivity were determined. There was a significant difference in the mechanism of CVD deposition between the two compounds. The maximum H-2/N-2 selectivity among our results was attained by combining sol dip-coating techniques with CVD of our novel precursor, Al( OPri)(2)(etac). (C) 1998 Chapman & Hall.