Basf Aktiengesellschaft

Basf Se Corporation

Thomas Grützner

Eckhard Stroefer

Ulrich Steinbrenner

Achim Stammer

Hans Hasse

Markus Siegert

Neven Lang

Thorsten Friese

Sergej Blagov

Eckard Stroefer

Michael Ott

Process for preparing high-concentration gaseous formaldehyde having a molar CHO:HO ratio of &#x2267;0.6 from an aqueous formaldehyde solution by evaporation of at least part of the solution, in which the aqueous formaldehyde solution is heated to a vaporization temperature T and the gas phase formed is taken off, wherein the evaporation temperature T obeys the relationship:T[&#xb0; C.]&#x2267;T'[&#xb0; C.]where T&#x2032;(c)=A+B&#xd7;(c/100)+C&#xd7;(c/100)+D&#xd7;(c/100)andA=+68.759, B=+124.77, C=&#x2212;12.851, D=&#x2212;10.095,where c is the instantaneous CHO content of the aqueous formaldehyde solution during the evaporation in percent by weight and is from 20 to 99% by weight.

Method for preparing highly concentrated, gaseous formaldehydes

Process for preparing high-concentration formaldehyde solutions having a CHO content of &#x2267;50% by weight from an aqueous formaldehyde solution having a lower CHO content by evaporation of part of this solution (partial evaporation), in which the aqueous formaldehyde solution is heated to an evaporation temperature T at which the gas phase becomes enriched in water relative to the liquid phase and the gas phase formed is taken off continuously or discontinuously, wherein the evaporation temperature T obeys the relationship:T[&#xb0; C.]&#x3c;T[&#xb0; C.]where T()=&#xd7;(/100)+&#xd7;(/100)&#xd7;(/100)and

Production of high-concentration formaldehyde solutions

Method of stabilizing high-concentration formaldehyde solutions having a CHO content of &#x3e;70% by weight against precipitation of solids, which comprises heating the high-concentration formaldehyde solution at a heating rate of at least 5&#xb0; C./min to a temperature of from 80&#xb0; C. to 200&#xb0; C. immediately after it has been prepared and storing it at a temperature in this range.

Method for thermal stabilization of highly concentrated formaldehyde solutions

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Stuttgart, Germany

Thomas Grützner