SEPARATING METHOD FOR POLYOL MIXTURES WITH CLOSE BOILING POINTS

摘要

Disclosed is a separating method for polyol mixtures with close boiling points. Using glycol containing dihydric or polyhydric fusel (for example, 1,2-propanediol and 1,2-butanediol) as a raw material, under the action of an acid catalyst, the dihydric or polyhydric fusel is subjected to (1) a dehydration reaction, (2) pinacol rearrangement, and (3) an acetal or ketol reaction, to generate aldehydes (a small quantity), acetal, and ketol (little), which are collected through distillation; meanwhile, a reaction liquid is further separated to obtain high purity glycol. The present invention provides a way to remove dihydric or polyhydric fusel from glycol through a liquid-phase dehydration reaction, the reaction condition is gentle, and the energy consumption is relatively low; the removal rate is relatively high for 1,2-butanediol which is hard to remove in a common method, and a glycol product with high purity is obtained; meanwhile, an acetal or ketol compound with a relatively high byproduct additional value can also produce some basic chemical raw materials such as acetaldehyde, propionaldehyde, and acetone. The present invention is a green and environmentally friendly technology for converting a glycol raw product that is hard to be separated into high purity glycol and other chemical products.