Thin inorganic semipermeable membranes prodn. - by immersing microporous alumina carrier in boehmite sol and drying and heating lyogel layer obtd

摘要

Dry, tear-free, mechanically and chemically stable, thin semipermeable inorganic membranes with a thickness of less than 20 microns are made by (1) coating a dry microporous inorganic carrier with a thickness of 50 microns to 5 mm and a pore dia. of up to 5 microns and made of sintered inorganic oxides, by immersion in a stable sol. of colloidal metal oxide or hydroxide particles with a particle size of 3 nm to 2 microns in which the concn. of the disperse phase in a non-solvent for the metal (hydr)oxide particles is 0.01-25 wt.% (esp. 0.5-5 wt.%), and in which the sol. in the border layer is first converted into a lyogel; (2) removing the carrier from the liq. and air drying to form a xerogel 1-20 microns thick and (3) heating to at least 390 deg.C.