Method of preparation of porous membranes and adsorbents

US4374933A · kind A · utility

Assignee

• FRAUNHOFER-GESELSCHAFT · DE

Inventors

• Horst Scholze · Würzburg, DE
• Helmut Schmidt · Riegelsberg, DE
• Harald Bottner · Glückstadt, DE

Key dates

• Filing date: Mar 23, 1982
• Grant date: Feb 22, 1983
• Expiry date: Mar 23, 2002

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08G77/22
• WIPO field: Chemical engineering
• WIPO sector: Chemistry

Abstract

Silicic acid heteropolycondensates made from hydrolyzable silicic acid derivatives and substituted silanes, optionally with either or both of one or more functional silanes and non-volatile metal oxides or their precursors are made by a known technique, in which the reaction mixture is hydrolyzed and condensed by the action of water and a condensation catalyst, the latter being employed in an amount up to 3% by weight, based upon the weight of the reaction mixture. Improved heteropolycondensates usable as adsorbents and porous membranes can be made by using greater amounts of catalyst, ranging up to 75% by weight, based upon the weight of the reaction mixture. These improved products are very stable in use and are characterized by a pore structure which includes fine pores and coarse pores, whereby products in the form of membranes can have an asymmetrical structure, if desired.