Research And Process Design Of Separation And Purification Of 1,2-Propanediol Through Reactive Distillation

After processing industry, the by-product of glycerin hydrogenation contains a large amount of 1,2-propylene glycol (PG) and a small amount of ethylene glycol (PG). Due to the high boiling point and the strong hydrophilic of PG and EG, it is difficult to separate and purify PG through directly distillation and it is also with high energy consumption. However, the reacted product of glycols and acetaldehyde (2,4-dimethyl-1,3-epoxy-dioxolane (24DMD) and 2-methyl-1,3-dioxolane (2MD)) can be easily separated by distillation.This paper studies the reaction kinetics of PG and EG with acetaldehyde, and investigated the reaction conditions, such as the ratio of raw material, the selection of catalyst, reaction temperature etc., to obtain acetal reaction kinetics equations separately: The hydrolysis reaction of 24DMD and 2MD were studied and the hydrolysis reaction kinetics equations were also obtained respectively:In this paper, the Aspen software was used to simulate the reaction process of PG rectification separation and purification. Meanwhile,separation process was designed, and investigated the feed position, the influence of pressure, reflux ratio and other operating parameters which would influence the purity of PG. At the end of the simulation progress, obtaining the highly purified PG, the mass fraction is 99.9601%, the yield is 35 kmol/h, the recovery is 73%.The basic data for the amplification of industrialization provides the reliable theory basis.