| 摘要 |
<p>Concentrated aqueous solutions of formaldehyde are manufactured by the oxidative dehydrogenation of methanol with air in the presence of a silver crystal catalyst bed and of steam, at a temperature from 550 to 780.degree.C, followed by absorption, in water, of the formaldehyde formed. According to the invention, the reaction is carried out with a throughput of from 1 to 3 tonnes of methanol per square meter of catalyst bed cross-section per hour in the presence of from 0.1 to 1.8 moles of water and from 0.04 to 0.4 mole of formaldehyde per mole of total methanol fed to the catalyst, the formaldehyde and from 0.1 to 1.8 moles of water per mole of total methanol fed to the catalyst are taken from the reaction mixture after the reaction and added to the starting mixture, and (a) a part of the formaldehyde and water is abstracted from the formaldehyde solution, formed in the absorption stage, by means of the air fed to the reaction, at from 60 to 90.degree.C, or (b) a part of the formaldehyde solution formed in the absorption stage is vaporized and recycled to the reaction, or (c) simultaneously a part of the formaldehyde and water is abstracted from the formaldehyde solution, formed in the absorption stage, by the air fed to the reaction, at from 60 to 90.degree.C, and a part of the formaldehyde solution formed in the absorption stage is vaporized and recycled to the reaction. The formaldehyde solution obtained by this process may be used as a disinfectant, tanning agent, reducing agent and starting material for the manufacture of synthetic resins, adhesives and plastics.</p> |
