C18 series fatty acid and C20-C22 series fatty acid fine separation method

Abstract

The invention discloses a C18 series fatty acid and C20-C22 series fatty acid fine separation method. The method includes: pretreating the raw material animal and vegetable oil by a ionic liquid to obtain high-yield and low-acid value biodiesel, i.e. a mixture of a variety of fatty acid methyl esters, with the process being simple, green and environment-friendly; then placing the obtained biodiesel in a pressured reduced rectification tower kettle, taking the ionic liquid as an extraction agent to conduct extraction pressured reduced rectification, and collecting methyl stearate, methyl oleate and methyl linoleate or eicosapentaenoic acid methyl ester and docosahexaenoic acid methyl ester with mass percentage purity of over 98% at the tower top. The method provided by the invention makes up the blank of the prior art, has a convenient operation process, provides the operation process for separation of long-chain fatty-acid methyl esters with a same carbon number, different double-bond numbers and poor heat sensitivity, and lays the foundation for fine separation of fatty acid methyl ester.

Description

technical field [0001] The invention relates to a method for the fine separation of C18 series fatty acids and C20-C22 series fatty acids, in particular, extracting, depressurizing, rectifying, separating and purifying pretreated animal and vegetable oils by using ionic liquid as an extractant and obtaining stearic acid therefrom Methyl ester, methyl oleate and methyl linoleate or methyl eicosapentaenoate and methyl docosahexaenoate. Background technique [0002] my country has a vast territory and abundant natural resources, among which there are a large number of fatty acid resources of great value to people's production and life, such as C18 series fatty acids, and omega-3 and omega-6 unsaturated fatty acids. C18 series fatty acids mainly include stearic acid (octadecanoic acid), oleic acid (9-octadecenoic acid) and linoleic acid (9,12-octadecadienoic acid), which are mainly found in vegetable oils , widely used in many fields such as additives, oil additives, surfactant...

AI Technical Summary

Problems solved by technology

For the separation of long-chain fatty acid methyl esters, common methods include traditional rectification, urea inclusion, supercritical extraction, and low-temperature cryocrystallization, etc., but the separation purity of the above methods is generally not high, and usually only relatively high-purity saturated fatty acids can be obtained Methyl esters and unsaturated fatty acid methyl ester products, but it is almost impossible to obtain a single high-purity fatty acid methyl ester, especially for methyl stearate, methyl oleate and methyl linoleate, few people do it

figure 1 (a) is methyl palmitate (C16:0); (b) is methyl stearate (C18:0); (c) is methyl oleate (C18:1); (d) is linseed oil Acid methyl ester (C18:2), through figure 1 It can be seen that the difference in the structure of the latter three is only one to two double bonds, which results in very little difference in physical and chemical properties between the latter three, and conventional separation methods are rarely able to completely separate the three substances. separated; figure 2 (a) is eicosapentaenoic acid methyl ester (C20:5); (b) is docosahexaenoic acid (C22:6), through figure 2 It can be seen that methyl eicosapentaenoate and methyl docosahexaenoate belong to fatty acid methyl esters with long carbon chains and polyunsaturated bonds. Separation methods such as distillation and supercritical extraction are easy to cause deterioration of raw materials, and it is almost impossible to effectively separate the two through urea inclusion and low temperature freezing crystallization.

In summary, methyl stearate, methyl oleate and methyl linoleate or methyl eicosapentaenoate and methyl docosahexaenoate are completely separated to obtain a single The technology of fatty acid methyl ester is rarely reported, which seriously hinders the further research and application of high-purity and high value-added fatty acid methyl ester

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