A kind of separation and purification method of by-product of ester bond reaction of oil

Abstract

The invention discloses a separation and purification method of oil transesterification reaction by-products. At present, after transesterification reactions of oil are completed, by-product phases are directly layered and separated; the by-product phases are large in stickiness and easy to stick to walls, particularly, during industrial production layering, liquid surfaces are difficult to delimit and separate, the operation difficulty is large, the separation process is crude, so that the product yield is reduced, and the purifying difficulty is large. In accordance with the by-product phases after an alcoholysis reaction or a saponification reaction in which glyceride ester bonds participate, a polarity solvent is firstly used for adjusting the polarity and the stickiness of the system, and complete separation of the by-product phases from main products is realized; then, regulating the pH value of the by-product phases is combined with rectification or multistage molecular distillation so as to separate glyceride, and short chain alcohol ester or / and free fatty acids; through crystallization filtering, inorganic salts are separated; finally, the polarity solvent is recovered, and then rectification is preformed, so that high-purity glycerine is obtained. The separation and purification method disclosed by the invention realizes recovering and purifying of components, so that the utilization value of the by-product phases is greatly increased, and besides, the yield and the competitiveness of the main products are also increased.

Description

technical field [0001] The invention relates to a method for recycling reaction by-products, in particular to a method for separating and purifying by-products produced in alcoholysis reactions or saponification reactions in which glyceride bonds participate. Background technique [0002] Natural oils exist in the form of triacylglycerols. In practical applications, due to the complex composition and high boiling point of glycerolipids, it is difficult to purify, which restricts its application. The reaction of glyceride ester bonds is the basis for the realization of transesterification and hydrolysis of oils. It is very important and common in oil industry production. According to production needs, free acids or other fatty acids with simple structure and easy purification can be prepared from glycerides through the reaction of ester bonds. Short-chain alcohol esters, and subsequent purification or reaction can greatly expand the application space of oils. For example, fa...

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Problems solved by technology

However, this process will convert the soap formed in the transesterification process into free acid and mix it into the oil layer after acidification, resulting in an increase in the acid value of the final product and affecting product quality.

[0010] CN203960088U and CN 103013673A disclose two kinds of separation devices for glycerol in biodiesel production. The former separates other components to purify glycerin by adjusting the pH value of the glycerin phase, because free acid will be produced in the acidification process, which will affect the quality of biodiesel; the latter Separation of glycerin by sedimentation method based on the density of oil phase and glycerin phase, it is difficult to effectively separate the components in the by-products

[0011] Generally speaking, the current research does not pay enough attention to the treatment of the by-product phase in the ester bond reaction of oils and fats. There is no detailed analysis of the composition, and there is no targeted recovery method for each component. Some existing recovery processes are also mainly for glycerol. The recovery, the deficiencies that exist in the recovery purification process mainly contain the following aspects:

[0012] 1. After the reaction is completed, the by-product phase is directly layered and separated. Due to the high viscosity, it is easy to stick to the wall, especially when it is difficult to define the boundary liquid level during industrial production layering, and the operation is difficult;

[0013] 2. The separation process is rough, and the by-product phase contains unreacted glycerides, short-chain alcohol esters, soaps, glycerin, alkalis, solvents and other components, which are not separated and purified separately, resulting in a decrease in product yield, Purification is difficult;

[0014] 3. Improper separation and purification methods lead to a decline in the quality of the main product. For example, acidification before stratification in the alcoholysis process will cause free acid to enter the upper main product, resulting in an increase in the acid value of the main product;