Hoechst Aktiengesellschaft

Ticona Gmbh

Gerhard Geiss

Ude Scheunemann

Andreas Zimmermann

Werner Prass

Werner Hickel

Elke Schweers

Harald Werner

Heinz Alexander

Gunther Appel

Jacqueline Bauer

Olaf Althoff

Frank Olschewski

Helmut Tr&auml;nkler

Elfriede Hufsky

Hans-Karl Muller

A process for the gas-phase trimerization of formaldehyde to give trioxane using solid phosphoric acid catalysts. Particularly suitable catalysts for this process are SPA catalysts (solid phosphorous acid), for example &ldquo;silicon phosphates&rdquo;. The main advantage of this catalyst system is its simple and inexpensive production and ready availability and also, in particular, its improved long-term stability compared to the few previously described catalysts which are mostly based on supported heteropolyacids.

Trimerization of formaldehyde in the gas phase

Composition containing an aerogel, method of producing said composition

To produce a composite membrane, the solution of a polymer in a volatile organic solvent is spread on water, the solvent is allowed to evaporate, the polymer is crosslinked and the polymer film formed is transferred to a porous support membrane. The polymer is preferably a polysiloxane which is cross-linked via polymer-bonded OH groups. The composite membrane is suitable, inter alia, for pervaporation.

Composite membrane and process for its production

Growing community of inventors

Liederbach, Germany

Gerhard Geiss