Study On Separation Technology Of 1, 2-butanediol From Corn-based Mixed Polyols

1,2-butanediol,for the low viscosity and low freezing point characteristics,can be used to make polyester polyols with low viscosity,good water resistance and softness properties.1,2-butanediol also can be used as raw materials of polyurethane,as well as raw materials of cosmetic moisturizer,medicine,pesticide,pesticide stabilizer and so on.At present,the main method to produce 1,2-butanediol is hydration of epoxide butane which is characterized by heavy pollution,complex process and high cost for the heavy use of oil resources,Na OH and H2SO4.Based on the above,scholars are trying to find techniques to obtain biologically based 1,2-butanediol in recent years.This experiment is based on corn-based mixed polyols A and B,which produced by Changchun Dacheng Industrial Group Co.Ltd,containing 1,2-butanediol.Firstly,corn-based mixed polyols A and B were analyzed by gas chromatography in order to design the separation experiments.Results showed that components with little different boiling point were existed in both corn-based mixed polyols A and B.Propylene glycol,ethylene glycol,1,2-butanediol,2,3-butanediol were the main components of corn-based mixed polyols A,and 1,2-butanediol,2,3-butanediol were the main components of corn-based mixed polyols B.97%~98% purity 1,2-butanediol was gained by simple distillation,vacuum distillation and extraction methods respectively,and it could be applied in cosmetics,pesticides and foam materials.Azeotropic distillation progress was studied in order to achieve the 99% purity 1,2-butanediol.In this progress,the relative volatility of 1,2-butanediol and other polyols were increased,and the boiling point of azeotropic mixture of 1,2-butanediol and entrainer were decreased by introducing entrainer.And then,the azeotropic mixture was collected from the top of the column,and 1,2-butanediol was separated by condensing and partitioning.The entrainer was recovered.High purity 1,2-butanediol was obtained by rectification method.Firstly,three entrainers DJWA,DJWB and DJWC were used for the azeotropic distillation experiments,and DJWC was selected as the best entrainer.Then the optimum reflux ratio was selected as 10:1 by changing reflux ratio experiment and the optimum ratio of entrainer to raw material was 4:1 by changing ratio of entrainer to raw material.1,2-butanediol purity was higher than 99% by above technology.