Preparation of formaldehyde

摘要: Formaldehyde is prepared by (a) passing a mixture of methanol and water with concentration between 50 90% weight, based on the total weight two substances, into packed column which possesses packing having layer thickness not less than cm surface area 0.5 2 per 3 packing, liquid circulation from 15 to 90 g/min fed column, 10 45% in recycle liquid, temperature at point entry being 50° 86° C. bottom 10°-25° lower this, i.e. 40° 70° C., (b) separating off stripping air, an inert gas and/or exit gas, throughput tonnes hour m cross-section, (c) converting gaseous methanol, water, space velocity catalyst bed cross-section hour, presence silver 550° 750° (d) finally, cooling absorbing hot reaction gases, using resulting heat absorption and, if desired, condensation partially or completely for heating containing impurities used desired after stages before (d), measures stage (e) carried out, wherein formed passed through layers wire filter diameter 0.1 mm free volume 99.5 vol. %, one layer, flow rate 7 13 m/sec first 1 4 second layer. The formaldehyde obtainable process invention disinfectant, tanning agent, reducing agent useful starting material preparation synthetic resins, adhesives plastics.