2,2-dihydroxypropionic acid preparation method steps are as follows:
Add 980Kg of pure water in 3000L reactor, put 16Kg of activated carbon loaded sodium hydroxide, add 1000Kg of formaldehyde, drop 300Kg of n-propanal, drop finished for 20-60?? constant temperature 6-14h;
Add 10Kg of formic acid to neutralize the pH value between 6 and 7.2;
Transfer to oxidizing kettle, concentrate in oxidizing kettle under reduced pressure, recover part of unreacted formaldehyde;
Add 580Kg of hydrogen peroxide at elevated temperature, and carry out constant temperature of 60-90?? for 6-10h after dropping;
Add 400Kg to 800Kg of water, and concentrate under reduced pressure;
Concentrate to water between 5—8%, cool and crystallize, centrifuge to get 2,2-dihydroxymethylpropionic acid crude product. The mother liquor was filtered for recirculation recrystallization;
Add 1000kg of water to 1000kg of crude product, warm it up to 50-60?? with stirring, add a small amount of iron remover and about 5kg of activated carbon, and filter it after half an hour to remove the activated carbon. Concentrate again at atmospheric pressure to the water content between 25wt%~30wt% discharge cooling crystallization, and then centrifugation, drying and sieving and other treatments to get 2,2-dihydroxymethylpropionic acid product.
The crude mother liquor is re-concentrated and then recrystallized to extract the product again; the fine mother liquor is then concentrated, decolorized, crystallized, centrifuged and dried to recover the product again. The refined mother liquor is recycled and returned as crude mother liquor. The crude mother liquor after extracting products again is finally treated as waste water. The mother liquor after each filtration was well treated to recover 2,2-dihydroxymethylbutyric acid in the mother liquor and improve the product yield.
