CN113354532B

CN113354532B - Method for preparing high-purity sebacic acid

Info

Publication number: CN113354532B
Application number: CN202010257172.2A
Authority: CN
Inventors: 苏永胜; 崔兵; 刘普根
Original assignee: Wilmar Highpolymer Material Lianyungang Co Ltd
Current assignee: Wilmar Highpolymer Material Lianyungang Co Ltd
Priority date: 2020-04-02
Filing date: 2020-04-02
Publication date: 2023-04-07
Anticipated expiration: 2040-04-02
Also published as: CN113354532A

Abstract

The application provides a method for reducing the content of monofatty acid in a sebacic acid product and a method for preparing high-purity sebacic acid by a castor oil cracking method, and particularly comprises the step of enabling a crude monosodium sebacate solution to pass through a resin column for adsorption, wherein the resin column comprises a nonionic adsorption resin, preferably a nonionic macroporous adsorption resin, and more preferably a macroporous styrene resin. The sebacic acid prepared according to the present application is highly pure, in particular the total content of mono-fatty acids therein can be reduced to below 1 wt.%, for example below 0.5 wt.% or even below 0.2 wt.%.

Description

Method for preparing high-purity sebacic acid

Technical Field

The invention relates to the field of preparation of sebacic acid, in particular to the field of preparation of sebacic acid by a ricinoleic acid cracking method, and more particularly relates to a preparation method of high-purity sebacic acid.

Background

A series of polymerization products can be prepared by taking sebacic acid as a raw material, such as a high-quality plasticizer, a binder, a dielectric liquid in the electronic capacitance industry and the like, the products have high requirements on the quality indexes of the sebacic acid such as chromaticity, ash content and the like, and the existing industrial sebacic acid can not meet the quality requirements. Therefore, the industrial sebacic acid is required to be used as a raw material, and the purification and refining process is carried out on the industrial sebacic acid, so that the obtained refined sebacic acid can meet the quality requirement of the industry on the sebacic acid.

Currently, research on industrial manufacturing methods of sebacic acid is active at home and abroad. Such as the high temperature alkali fusion ricinoleic acid process; a castor oil cracking process; cyclodecane and cyclodecanol oxidation by nitric acid; ozonolysis of undecylenic acid or its ethyl ester; electrolytic adipic acid method, microbial fermentation method, and the like.

The existing methods mainly comprise methods such as organic solvent extraction, reduced pressure distillation, regional melting purification and the like.

The sebacic acid is refined by adopting a zone melting method, the content of the raw material sebacic acid is 99.5 percent, the sebacic acid reaches 99.8 percent after zone melting purification, and the inert gas helium is used as protective gas. However, this method is not effective in reducing the monoacid content of sebacic acid products.

Japanese patent No. 53-82717 discloses a purification method in which a crude sebacic acid product is dissolved in a solvent, urea and sebacic acid are added to produce a urea inclusion, the inclusion is separated from a sebacic acid solution, and the inclusion is decomposed to obtain sebacic acid and urea. Preferred solvents include alcohols such as methanol, ethanol, and propanol, which can dissolve sebacic acid and urea and can easily precipitate a sebacic acid-urea inclusion compound. Another decomposition method comprises heating to 90-100 deg.C in the presence of hydrocarbon solvent such as benzene, toluene, pentane and hexane, separating decomposed urea as solid insoluble in the hydrocarbon solvent, and distilling off sebacic acid. After the treatment by the method, the sebacic acid product with the purity of more than 99.5 percent can be obtained. The method is complex to operate and cannot effectively reduce the content of the monoacid in the sebacic acid.

However, there is still a higher demand for the purity of sebacic acid, and it is also desirable to provide a convenient or inexpensive process for preparing high purity sebacic acid.

Summary of The Invention

In a first aspect, the present application provides a process for reducing the content of mono fatty acids in a sebacic acid product, comprising the steps of:

(1) Providing a crude monosodium salt of sebacic acid comprising a mono fatty acid and/or a sodium salt thereof in aqueous solution;

(2) Adsorbing the crude sebacic acid monosodium salt aqueous solution containing the mono-fatty acid and/or the sodium salt thereof through a resin column to obtain an adsorbed sebacic acid monosodium salt aqueous solution; and

(3) Converting the adsorbed aqueous solution of monosodium sebacate to a sebacic acid product,

wherein the resin column comprises a non-ionic adsorption resin.

In some embodiments, the resin column comprises a non-ionic macroporous adsorbent resin.

In some embodiments, the resin column comprises a macroporous styrene resin.

In some embodiments, the mono fatty acid and/or sodium salt thereof comprises from about 1% to about 4% by weight of the monosodium salt of sebacic acid in the aqueous solution of crude monosodium salt of sebacic acid, wherein sodium salts are calculated as their corresponding acids.

In a second aspect, the present application provides a method for preparing sebacic acid by a castor oil cracking method, comprising the step of passing a crude aqueous solution of monosodium sebacate through a resin column for adsorption, wherein the resin column comprises a non-ionic adsorption resin.

In some embodiments, the resin column comprises a macroporous styrene resin.

In some embodiments, when the crude aqueous monosodium sebacate salt solution is adsorbed by a resin column, the temperature of the resin column is from about 20 to about 100 ℃, for example from about 40 to about 90 ℃, preferably from about 50 to about 85 ℃, more preferably from about 65 to about 75 ℃.

In some embodiments, the rate of passage of the crude aqueous solution of monosodium sebacate through the resin column is from about 0.1 to about 10 BV/hour, preferably from about 0.5 to about 5 BV/hour, more preferably from about 1 to about 2 BV/hour, based on the number of volumes of monosodium salt solution (defined as BV) passed through the volume of resin.

In some embodiments, the non-ionic adsorbent resin is a regenerated resin obtained by washing a used resin with a regenerating agent such as water, methanol, ethanol, aqueous sodium hydroxide solution.

In some embodiments, the pH of the aqueous crude monosodium sebacate solution may be adjusted prior to adsorption through a resin column, for example to a pH of about 3 to about 6.5, preferably to a pH of about 4.0 to about 6.5, more preferably to a pH of about 5.0 to about 6.2.

In some embodiments, the pH of the aqueous solution of crude monosodium sebacate may be adjusted by the addition of a mineral acid.

In some embodiments, the inorganic acid is selected from sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, and the like.

In some embodiments, the ricinoleic acid cleavage step is preceded by a step of hydrolysis of castor oil to ricinoleic acid.

In some embodiments, the step of passing through the resin column further comprises the step of converting the adsorbed aqueous solution of monosodium sebacate to sebacic acid.

In some embodiments, the step of converting the adsorbed aqueous solution of monosodium sebacate to sebacic acid comprises acidification, crystallization, filtration, drying and the like.

In a third aspect, the present application provides a sebacic acid product prepared by the aforementioned method.

In a fourth aspect, the present application provides the use of a non-ionic adsorbent resin for reducing the content of mono fatty acids, in particular for reducing the content of mono fatty acids in a sebacic acid product.

In some embodiments, the non-ionic adsorbent resin is optionally a non-ionic macroporous adsorbent resin, further optionally a macroporous styrene resin.

Drawings

FIG. 1: a general flow diagram of a castor oil cracking method for preparing sebacic acid.

Detailed Description

While this application contains many specifics, these should not be construed as limitations on the scope of the invention or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particular inventions. Certain features that are described in the context of separate embodiments in this application can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

Unless otherwise indicated, the terms herein have the same meaning as commonly understood by one of ordinary skill in the art, e.g., in reference to the starting materials and products, operating steps, process parameters, equipment and tools used, and units of values.

As used herein, the terms "comprises" and "comprising" mean either open or closed. For example, the term "comprises" or "comprising" may mean that other elements or steps or other elements not listed may also be included or included, or that only the listed elements or steps or other elements may be included or included.

Herein, the term "about" (e.g., in component amounts and reaction parameters) is to be interpreted in the sense that it is generally understood by those skilled in the art. In general, the term "about" can be understood as any value within plus or minus 5% of the given value, e.g., about X can represent any value within the range of 95% to 105% by weight.

It is also to be understood that the specific values given herein (e.g., in component ratios, temperatures, and pH) are to be understood not only as individual values, but are also to be construed as providing endpoints of a range and other ranges can be provided in combination with each other.

The application is based on an improvement on the conventional castor oil cracking method for preparing sebacic acid. As shown in fig. 1, the conventional castor oil cracking process includes the following main steps:

(1) And (3) cracking ricinoleic acid at high temperature in the presence of alkali and phenol to obtain a cracked material. Here, ricinoleic acid is obtained, for example, from the hydrolysis of castor oil.

(2) Dissolving the cracking material to obtain a disodium salt solution, adjusting the pH value to 6-7 by an acidification 1 working section, and skimming fatty acid by liquid separation to obtain a crude monosodium sebacate solution;

(3) And adsorbing and decoloring the obtained crude monosodium sebacate solution by resin, adjusting the pH value to 1-2 by an acidification 2 working section, cooling, crystallizing, filtering and drying to finally obtain a finished product of the sebacate.

However, in the conventional castor oil cracking method, the prepared sebacic acid finished product often contains single fatty acids such as C7-C12 single fatty acids with low content, and the polymerization degree of the product is affected when the sebacic acid finished product is applied to a raw material of a high-end polymer. Therefore, it is necessary to reduce the content of mono-fatty acids to increase the purity of the finished sebacic acid to meet the requirements of high-end polymers.

The inventors of the present application have unexpectedly found that the sodium monofatty acid mixed in the aqueous solution of monosodium sebacate can be easily removed or reduced in its content by adsorption on a resin column, in particular by adsorption on a non-ionic resin, and thus the overall content of monofatty acids in the finished product of sebacic acid can also be easily reduced.

Accordingly, in a first aspect, the present application provides, first, a process for reducing the content of mono fatty acids in a sebacic acid product, comprising the steps of:

wherein the resin column comprises a non-ionic adsorption resin.

In step (1) of the process, an aqueous solution of crude monosodium salt of sebacic acid comprising mono fatty acids and/or sodium salts thereof is provided.

In one case, the aqueous solution of crude monosodium sebacate may be, for example, an aqueous solution from a preceding step of a particular process (e.g., the castor oil cracking process described above). The crude aqueous solution of monosodium sebacate at this point will generally contain impurities originating from previous processing steps. For example, in a castor oil cracking process, impurities can include, but are not limited to, mono fatty acids (e.g., C7-C12 mono fatty acids), sodium salts of mono fatty acids (e.g., C7-C12 mono fatty acid sodium salt), fatty diacid sodium salts, phenols, pigments, and the like.

In another case, the aqueous solution of the crude monosodium sebacate may also be formulated separately for purification purposes. For example, existing sebacic acid products may have a low purity due to the presence of mono-fatty acids. Addition of an appropriate amount of liquid base (e.g., naOH solution) to the sebacic acid product will result in a monosodium salt solution of sebacic acid containing mono-fatty acids and/or their sodium salts.

The "mono fatty acid" herein is typically one or more of C7-C12 mono fatty acids, or any combination thereof. C7-C12 mono-fatty acids include, but are not limited to, n-heptanoic acid, n-octanoic acid, n-nonanoic acid, n-decanoic acid, n-undecanoic acid, n-dodecanoic acid. The "sodium salt of a mono fatty acid" herein is typically one or more of the sodium salts of C7-C12 mono fatty acids, or any combination thereof. Sodium salts of C7-C12 mono-fatty acids include, but are not limited to, the sodium salts of n-heptanoic acid, n-octanoic acid, n-nonanoic acid, n-decanoic acid, n-undecanoic acid, n-dodecanoic acid.

Herein, "providing a crude aqueous solution of monosodium sebacate comprising mono fatty acids and/or their sodium salts" includes either of the two cases described above. In some embodiments, the mono fatty acid and/or sodium salt thereof comprises from about 1% to about 4% by weight of the monosodium salt of sebacic acid in the aqueous solution of crude monosodium salt of sebacic acid, wherein sodium salts are calculated as their corresponding acids. That is, in calculating the weight, the weight of equimolar amounts of mono fatty acid is calculated, corresponding to the mono fatty acid sodium salt; calculated is the weight of equimolar sebacic acid corresponding to the monosodium salt of sebacic acid.

In the (2) step of the process, the crude aqueous solution of monosodium sebacate containing mono fatty acids and/or their sodium salts is adsorbed by a resin column to obtain an adsorbed aqueous solution of monosodium sebacate.

"nonionic adsorbent resin" refers to a polymeric resin that does not contain ionic groups in its molecular structure. The nonionic adsorbent resin includes polystyrene type adsorbent resin, polyacrylic acid type adsorbent resin, and the like. In some preferred embodiments polystyrene type adsorbent resins are used.

In a further preferred embodiment, a macroporous adsorbent resin is used. The macroporous adsorbent resin generally has a particle size of 20-60 mesh. In some more preferred embodiments, the use of a non-ionic macroporous adsorbent resin, particularly a macroporous polystyrene type resin, is used.

In step (3) of the process, the adsorbed aqueous solution of monosodium sebacate is converted into a sebacic acid product. The step comprises the steps of acidifying the obtained monosodium sebacate aqueous solution to the pH value of 1-2, cooling and crystallizing, filtering and drying and the like, thereby obtaining the final finished product of the sebacate.

After passing the crude aqueous solution of monosodium salt of sebacic acid comprising mono fatty acids and/or sodium salts thereof through a column of non-ionic resin, sebacic acid (mono sodium salt) and mono fatty acids (sodium salt) (e.g. C7-C12 mono fatty acids (sodium salt)) can be efficiently separated. Therefore, the content of the mono-fatty acid in the finally obtained sebacic acid product is effectively reduced. The content of the mono-fatty acid in the finished sebacic acid can be reduced to below 1 weight percent; advantageously, to below 0.5% by weight; more advantageously to below 0.2% by weight.

It is clear that this method of separating sebacic acid (monosodium salt) and mono-fatty acid (sodium salt), such as C7-C12 mono-fatty acid (sodium salt), can be conveniently integrated in a process of castor oil cracking (preparation of sebacic acid).

Thus, in a second aspect, the present application provides a method for preparing sebacic acid by a castor oil cracking process, comprising the step of passing an aqueous solution of crude monosodium sebacate through a resin column for adsorption, wherein the resin column comprises a non-ionic adsorption resin.

In the process of ricinoleic acid cleavage, crude monosodium sebacate is obtained after first acidification and fatty acid skimming. The crude monosodium sebacate salt is often mixed with various undesirable impurities including, but not limited to, mono fatty acids (e.g., C7-C12 mono fatty acids), mono fatty acid sodium salts (e.g., C7-C12 mono fatty acid sodium salts), sodium salts of other diacids, phenols, pigments, and the like.

In some preferred embodiments, the non-ionic adsorbent resin is a polystyrene-type adsorbent resin. In some preferred embodiments, a macroporous adsorbent resin is used. Thus, in some more preferred embodiments, a non-ionic macroporous adsorbent resin, particularly a macroporous polystyrene-type resin, is used.

When the crude aqueous solution of monosodium sebacate salt is passed through a resin column, the temperature of the resin column may be from about 20 to about 100 ℃. Further preferably, the temperature of the resin column may be from about 40 to about 90 ℃, more advantageously from about 50 to about 85 ℃, for example from about 65 to about 75 ℃. In this case, the content of the monofatty acid (sodium) can be reduced and the process can be more conveniently performed.

Because the resin column will have a reduced performance after adsorption treatment with a certain amount of monosodium salt. At this point, the regeneration of the appropriate regenerant may be selected such that all or most of its performance is restored. In some embodiments, the non-ionic adsorbent resin may be a regenerated resin. That is, the nonionic adsorbent resin which has been used, for example, the nonionic adsorbent resin which has been used and failed in the previous preparation process of sebacic acid, can be regenerated by washing with a regenerating agent such as water, methanol, ethanol, aqueous sodium hydroxide solution.

In some embodiments, the rate at which the crude aqueous solution of monosodium sebacate passes through the resin column is controlled. A smaller passing rate is advantageous in improving the adsorption effect, but at the same time, reduces the throughput per unit time, and therefore, in order to balance the adsorption effect and the treatment efficiency per unit time, it is necessary to select an appropriate passing rate through the resin column. The number of volumes of monosodium salt solution passed through the volume resin was defined as BV. In a preferred embodiment, the rate of passage of the crude aqueous solution of monosodium sebacate through the resin column may be from about 0.1 to about 10 BV/hour, preferably from about 0.5 to about 5 BV/hour, more preferably from about 1 to about 2 BV/hour.

In both cases, the pH of the aqueous solution of the crude monosodium sebacate may be adjusted prior to passing through the resin column. For example, the pH can be adjusted by adding a mineral acid. The inorganic acid may be sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, etc. In some preferred embodiments, the pH of the crude aqueous monosodium sebacate solution is adjusted to a pH of 3 to 6.5 prior to passage through the resin column. In a more preferred embodiment, the pH is adjusted to a value of 4.0 to 6.5, in particular 5.0 to 6.2, for example to a pH of 5.0, 5.2, 5.4, 5.6, 5.8 or 6.0. In this case, the content of the mono-fatty acid (sodium salt) in sebacic acid (monosodium salt) can be more remarkably reduced.

After passing through the resin column, the aqueous solution of the monosodium sebacate is subjected to the technical processes of further acidification, cooling crystallization, filtration, washing and the like, and finally the finished product of the sebacate is obtained. The finished sebacic acid, prepared according to the process herein, has a content of mono-fatty acids lower than 1% by weight, advantageously lower than 0.5% by weight, more advantageously lower than 0.2% by weight.

Thus, in a third aspect, the present application also provides a sebacic acid product prepared by the above method. The purity of the sebacic acid product is quite high, enabling a purity of more than 98.5%, and it is particularly important that the content of mono-fatty acids is less than 1%, advantageously less than 0.5%, more advantageously less than 0.2%.

In the present application, especially, the monosodium salt of sebacic acid is effectively separated from the mono-fatty acid or its sodium salt by using a non-ionic adsorption resin. Accordingly, the present application also provides in a fourth aspect the use of a non-ionic adsorbent resin for reducing the content of mono fatty acids, in particular for reducing the content of mono fatty acids in a sebacic acid product.

In a fourth aspect, the present application provides the use of a non-ionic adsorbent resin for reducing the content of mono fatty acids. In particular, the application provides the use of a non-ionic adsorbent resin to reduce the content of mono fatty acids in a sebacic acid product.

In some embodiments, the non-ionic adsorbent resin may be a non-ionic macroporous adsorbent resin. In a further preferred embodiment, the non-ionic adsorption resin may be a macroporous styrene resin.

Examples

The present application is further illustrated with reference to specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present application. Experimental procedures without specific conditions noted in the examples below are generally carried out under conventional conditions or under conditions recommended by the manufacturer. Percentages are by mass unless otherwise indicated. Unless defined otherwise, all terms of art or science used herein have the same meaning as is familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to those described herein can be used in the present application. The preferred methods and materials described herein are exemplary only.

In each of the examples and comparative examples, the sources of the raw materials used were as follows:

crude aqueous solution of monosodium sebacate: feng Yi Polymer materials (Liyunggang) Ltd

Macroporous styrene resin: xian lan is known as science and technology materials, inc.

Macroporous decolorizing resin column: type D201, chemical industry three factories of New river county in Hebei.

Blank experiment:

and (3) taking 200mL of crude monosodium sebacate aqueous solution, dropwise adding concentrated sulfuric acid under boiling, adjusting the pH to 2, cooling to room temperature under stirring, and filtering and collecting precipitated solids to obtain a finished product of sebacic acid. And detecting the fatty acid composition of the finished product sebacic acid by using gas chromatography after methyl esterification. The total content of mono-fatty acids was tested to be 2.50% and the content of dodecanedioic acid 0.71%.

Example 1:

1000mL of crude monosodium sebacate aqueous solution was taken, in which the content of mono fatty acid (sodium) was 2.50% with respect to the content of sebacylic acid, and the content of dodecanedioic acid was 0.71%. The pH value is adjusted to 6.5, the temperature is controlled to be 80 ℃, and the mixture passes through a macroporous styrene adsorption resin column, and 10g of resin is filled in the resin column. The rate of passage of the monosodium salt solution through the resin column was 2 BV/hour. Collecting the adsorbed monosodium salt solution, and performing the same process as the blank experiment to obtain a sebacic acid finished product, wherein the total content of the monofatty acid is 0.63% and the content of the dodecanedioic acid is 0.72%.

Example 2:

taking 500mL of crude monosodium salt aqueous solution of sebacic acid, wherein the content of fatty acid (sodium) relative to the content of sebacic acid is 2.50%, adjusting the pH value to 6.2, controlling the temperature to be 70 ℃, passing through a macroporous styrene adsorption resin column, and filling 10g of resin in the resin column. The rate of passage of the monosodium salt solution through the resin column was 1 BV/hour. Collecting the adsorbed monosodium salt solution, and carrying out the same process as the blank experiment to obtain a sebacic acid finished product, wherein the total content of the monofatty acid is 0.32%, and the content of the dodecanedioic acid is 0.70%.

Example 3:

taking 300mL of crude monosodium sebacate aqueous solution, wherein the content of fatty acid (sodium) relative to the content of sebacate is 2.50%, adjusting the pH value to 5.6, controlling the temperature to be 70 ℃, passing through a macroporous styrene adsorption resin column, and filling 10g of resin in the resin column. The rate of passage of the monosodium salt solution through the resin column was 2 BV/hour. Collecting the adsorbed monosodium salt solution, and performing the same process as the blank experiment to obtain a sebacic acid finished product, wherein the total content of the monofatty acid is 0.15% and the content of the dodecanedioic acid is 0.69%.

Example 4:

taking 200mL of crude monosodium sebacate aqueous solution, wherein the content of fatty acid (sodium) relative to the content of sebacic acid is 2.50%, adjusting the pH value to 5.8, controlling the temperature to be 65 ℃, passing through a macroporous styrene adsorption resin column, and filling 10g of resin in the resin column. The rate of passage of the monosodium salt solution through the resin column was 1 BV/hour. Collecting the adsorbed monosodium salt solution, and carrying out the same process as the blank experiment to obtain a sebacic acid finished product, wherein the total content of the monofatty acid is 0.06%, and the content of the dodecanedioic acid is 0.69%.

Example 5:

taking 300mL of crude monosodium sebacate aqueous solution, wherein the content of fatty acid (sodium) relative to the content of sebacate is 2.50%, adjusting the pH value to 6.0, controlling the temperature to be 45 ℃, passing through a macroporous styrene adsorption resin column, and filling 10g of resin in the resin column. The rate of passage of the monosodium salt solution through the resin column was 5 BV/hour. Collecting the adsorbed monosodium salt solution, and performing the same process as the blank experiment to obtain a sebacic acid finished product, wherein the total content of the monofatty acid is 0.66%, and the content of the dodecanedioic acid is 0.69%.

Example 6:

taking 300mL of crude monosodium sebacate aqueous solution, wherein the content of fatty acid (sodium) relative to the content of sebacate is 2.50%, adjusting the pH value to 5.0, controlling the temperature to be 75 ℃, passing through a macroporous styrene adsorption resin column, and filling 10g of resin in the resin column. The rate of passage of the monosodium salt solution through the resin column was 3 BV/hour. Collecting the adsorbed monosodium salt solution, and performing the same process as the blank experiment to obtain a sebacic acid finished product, wherein the total content of the monofatty acid is 0.08%, and the content of the dodecanedioic acid is 0.71%.

Example 7:

the resin used in example 1 was washed with 40mL of 5% sodium hydroxide solution and then with 20mL of deionized water to obtain a regenerated resin. 1000mL of crude monosodium sebacate aqueous solution, in which the content of monofatty acid (sodium) was 2.5% with respect to the content of sebacic acid, was taken, the pH thereof was adjusted to 6.5, the temperature was controlled at 80 ℃ and passed through the regenerated resin obtained above, and 10g of the resin was packed in a resin column. The rate of passage of the monosodium salt solution through the resin column was 2 BV/hour. Collecting the adsorbed monosodium salt solution, and performing the same process as the blank experiment to obtain a sebacic acid finished product, wherein the total content of the monofatty acid is 0.61%, and the content of the dodecanedioic acid is 0.70%.

Comparative example 1:

1000mL of crude monosodium sebacate aqueous solution was taken, in which the content of mono fatty acid (sodium) was 2.50% with respect to the content of sebacylic acid, and the content of dodecanedioic acid was 0.71%. The pH value is adjusted to 6.5, the temperature is controlled to be 80 ℃, and the mixture passes through a D201 type macroporous decolorizing resin column which is filled with 10g of resin. The rate of passage of the monosodium salt solution through the resin column was 2 BV/hour. Collecting the adsorbed monosodium salt solution, and performing the same process as the blank experiment to obtain a sebacic acid finished product, wherein the total content of the monofatty acid is 2.48%, and the content of the dodecanedioic acid is 0.70%.

The above data for examples 1-7 and comparative example 1 are summarized in table 1 below.

Therefore, the method can effectively reduce the total content of the mono-fatty acid in the sebacic acid finished product through a simple process method, so that the content of the mono-fatty acid in the sebacic acid finished product is reduced to a proper level, a high-quality sebacic acid finished product is obtained, and the requirement of a high-end polymerization product is met.

Claims

1. A process for reducing the content of mono fatty acids in a sebacic acid product comprising the steps of:

wherein the pH of the crude aqueous solution of monosodium sebacate is adjusted to 3 to 6.5 before adsorption through a resin column; the resin column comprises a non-ionic macroporous styrene resin.

2. The process according to claim 1, wherein the mono-fatty acids and/or their sodium salts constitute from 1 to 4% by weight of the monosodium salt of sebacic acid in the aqueous solution of crude monosodium salt of sebacic acid, wherein sodium salts are each calculated as their corresponding acids.

3. The process of claim 1, wherein the temperature of the resin column is 20 to 100 ℃ when the crude aqueous solution of monosodium sebacate is adsorbed by the resin column.

4. The method of claim 3, wherein the temperature of the resin column is 40 to 90 ℃.

5. The method of claim 3, wherein the temperature of the resin column is 50 to 85 ℃.

6. The method of claim 3, wherein the temperature of the resin column is 65 to 75 ℃.

7. The process of any one of claims 1 to 6 wherein the rate of passage of the crude aqueous monosodium sebacate solution through the resin column is from 0.1 to 10 BV/hour, based on the number of volumes of monosodium salt solution passed through the volume of resin.

8. The process of claim 7 wherein the rate of passage of the crude aqueous monosodium sebacate solution through the resin column is from 0.5 to 5 BV/hr in terms of the volume of monosodium salt solution passed through the volume of resin.

9. The process of claim 7 wherein the rate of passage of the crude aqueous monosodium sebacate solution through the resin column is from 1 to 2 BV/hour, based on the volume of monosodium salt solution passed through the volume of resin.

10. The method according to claim 1, wherein the nonionic macroporous styrene resin is a regenerated resin obtained by washing a used resin with a regenerating agent.

11. The process of claim 10, wherein the rejuvenating agent is selected from water, methanol, ethanol or aqueous sodium hydroxide.

12. The process of claim 1, wherein the pH of the aqueous crude monosodium sebacate solution is adjusted to 4.0 to 6.5 prior to adsorption through a resin column.

13. The process of claim 1, wherein the pH of the aqueous crude monosodium sebacate solution is adjusted to 5.0 to 6.2 prior to adsorption through a resin column.

14. The process of claim 1, wherein the pH of the aqueous solution of crude monosodium sebacate is adjusted by addition of a mineral acid.

15. The method of claim 14, wherein the mineral acid is sulfuric acid, hydrochloric acid, nitric acid, or phosphoric acid.

16. A method for preparing sebacic acid by castor oil cracking method comprises the steps of passing crude sodium sebacate monosodium salt water solution through a resin column for adsorption,

wherein the pH of the crude aqueous solution of monosodium sebacate is adjusted to 3 to 6.5 prior to adsorption through a resin column; the resin column is non-ionic macroporous styrene resin.

17. The process as claimed in claim 16, wherein the mono-fatty acids and/or sodium salts thereof constitute from 1 to 4% by weight of the monosodium salt of sebacic acid in the aqueous solution of crude monosodium salt of sebacic acid, each calculated as its corresponding acid.

18. The method of claim 16 wherein the temperature of the resin column is 20 to 100 ℃ when the crude aqueous monosodium sebacate solution is adsorbed by the resin column.

19. The process of claim 16, wherein the temperature of the resin column is from 40 to 90 ℃ when the crude aqueous solution of monosodium sebacate is adsorbed by the resin column.

20. The process of claim 16 wherein the temperature of the resin column is from 50 to 85 ℃ when the crude aqueous solution of monosodium sebacate is adsorbed by the resin column.

21. The process of claim 16 wherein the temperature of the resin column is from 65 to 75 ℃ when the crude aqueous solution of monosodium sebacate is adsorbed by the resin column.

22. The process of claim 16 wherein the rate of passage of the crude aqueous solution of monosodium sebacate through the resin column is from 0.1 to 10 BV/hour in terms of the number of volumes of monosodium salt solution passed through the volume of resin.

23. The process of claim 16 wherein the rate of passage of the crude aqueous solution of monosodium sebacate through the resin column is from 0.5 to 5 BV/hour in terms of the number of volumes of monosodium salt solution passed through the volume of resin.

24. The process of claim 16 wherein the rate of passage of the crude aqueous monosodium sebacate solution through the resin column is from 1 to 2 BV/hour in terms of the number of volumes of monosodium salt solution passed through the volume of resin.

25. The method according to claim 16, wherein the non-ionic macroporous styrene resin is a regenerated resin obtained by washing a used resin with a regenerating agent.

26. The method of claim 25, wherein the rejuvenating agent is selected from the group consisting of water, methanol, ethanol, and aqueous sodium hydroxide.

27. The process of claim 16, wherein the pH of the aqueous crude monosodium sebacate solution is adjusted to 4.0 to 6.5 prior to adsorption through a resin column.

28. The process of claim 16, wherein the pH of the aqueous crude monosodium sebacate solution is adjusted to a pH of 5.0 to 6.2 prior to adsorption through a resin column.

29. The process of claim 16, wherein the pH of the aqueous solution of crude monosodium sebacate is adjusted by addition of a mineral acid.

30. The method of claim 29, wherein the mineral acid is sulfuric acid, hydrochloric acid, nitric acid, or phosphoric acid.

31. The method of any one of claims 16-30, further comprising the step of converting the adsorbed aqueous solution of monosodium sebacate to sebacic acid after the step of passing through a resin column.

32. The method of claim 31 wherein the step of converting the adsorbed aqueous solution of monosodium sebacate to sebacic acid comprises acidification, crystallization, filtration and drying.

33. Use of a non-ionic macroporous styrene resin for reducing the content of mono fatty acids in an aqueous solution of monosodium sebacate.