Patent ID: 8277661

Claim:
A microporous organic-inorganic hybrid membrane based on silica, supported by a mesoporous layer, the microporous membrane having an average pore size of less than 1.5 nm, and in which between a portion of the Si—O—Si bonds have been replaced by moieties having the following formula: Si—C m H n —Si [I] in a molar ratio represented by the following formulae: Si 0.9-1.0 M 0.0-0.1 O 1.45-1.55 A 1 0.0-0.1 A 2 0.45-0.50 [A] or Si 0.9-1.0 M 0.0-0.1 O 1.45-1.55 A 1 0.30-0.36 A 2 0.30-0.35 [B] in which: A 1 is a monovalent organic moiety of the formula C r H s+1 bound to a silicon atom, A 2 is a divalent organic moiety of the formula C m H n bound to two silicon atoms, m=1-8, n=2m, 2m−2, 2m−4, 2m−6, or 2m−8, provided that n≧2, r=1−10, s=2r, 2r−2, 2r−4 or 2r−6, provided that s≧2, M is a metal selected from yttrium, lanthanum, titanium, zirconium, hafnium, aluminum, gallium, germanium and tin.