CN1088055C - Process for extracting alpha-or omege-alkadicarboxylic acid from fermented liquid and refining it - Google Patents

Abstract

The invention discloses a method for extracting and refining long-chain dicarboxylic acid from fermented liquid. After the fermented liquid is treated with an extraction solvent, the dicarboxylic acid product is transferred from the organic phase to the water phase by the back extraction method, and then passed through the acid Analysis, filtration, drying and other steps to obtain dicarboxylic acid products. Compared with the prior art, it not only simplifies the process steps, shortens the operation period, reduces the energy consumption, but also improves the working environment and operation safety, reduces the solvent consumption and reduces the air pollution.

Description

A method for extracting and refining α, ω-long-chain dicarboxylic acids from fermentation broth

The invention relates to a method for extracting and refining α, ω-long-chain dicarboxylic acid from fermented liquid.

At present, long-chain dicarboxylic acids are generally produced by biological oxidation methods at home and abroad, and the corresponding metabolites α, ω-long-chain dicarboxylic acids are obtained by biological oxidation of normal alkanes with different carbon numbers, and then extracted and refined from the fermentation broth. To obtain a product with higher purity, it is very difficult to refine and purify by conventional methods (such as filtration, centrifugation, crystallization, membrane separation, etc.), and the product purity and yield obtained are not high. Japanese patent JP56-15695 discloses a method of extracting with toluene solvent and back-extracting the organic phase with ethylene glycol. The method is to filter and sterilize the fermentation broth to obtain the clear liquid, acidify the crystal with HCl, and then extract with toluene. The organic phase was back extracted with an equal amount of ethylene glycol. The main disadvantage of this method is that the fermented liquid is viscous, the bacterium particles are tiny, and it is very difficult to filter and sterilize, which brings great trouble to the operation, especially when the fermented liquid is contaminated with miscellaneous bacteria. And the filter cake is viscous and difficult to filter dry, the product loss is large, and the yield is not high. Chinese patent CN1070394 discloses a method of extraction with ketone solvents, and its purpose is to solve the problems of low product recovery and difficult filtration. The terminated fermentation broth is heated, demulsified, unconverted alkanes are separated, acidified and crystallized, filtered and dried to obtain a dry filter cake (mainly composed of dicarboxylic acid and bacteria), and then dissolved in the filter cake with a ketone solvent under heating conditions Dicarboxylic acid, and then filter to remove bacteria and insoluble matter, cool down and crystallize, then filter to remove solvent, and dry the filter cake to obtain dicarboxylic acid product. Though this method has improved the yield of product, the main problem that exists is: (1) acidify crystallization, filter, dry at first after fermented liquid separates unconverted alkane, just carry out extraction then, such process is numerous and diverse, operation cycle (2) Since the product directly crystallizes from the solvent, the filter cake after filtration contains many solvents, and this part of the solvent is all volatilized during drying, which not only causes solvent loss, but also pollutes the environment.

The purpose of the present invention is to overcome above-mentioned deficiencies in the prior art, provide a kind of whole fermented liquid solvent extraction method, simplify technological process, shorten operating period, reduce solvent consumption and operating cost, thereby make product cost reduce.

A technical solution to realize the purpose of the present invention can be:

Main process of the present invention comprises:

(1) Separating and removing unconverted normal alkanes from the terminating fermentation broth;

(2) extracting and treating the fermented liquid containing α, ω-long-chain dicarboxylic acid and thalline obtained in step (1) with an organic solvent to obtain an organic phase layer in which the target product is dissolved;

(3) Separation and removal of insoluble impurities carried in the thallus and solvent phase by filtration while hot;

(4) the dicarboxylic acid product is transferred from the organic phase to the aqueous phase by back extraction;

(5) acid analysis from the resulting aqueous phase to obtain long-chain dicarboxylic acid crystals;

(6) Separating and drying the above crystals to obtain dicarboxylic acid products.

Another solution to realize the present invention can be:

(1) Separating and removing unconverted normal alkanes from the terminating fermentation broth;

(2) Treat the fermentation broth containing α, ω-long-chain dicarboxylic acid and thalline with an organic solvent to obtain an organic phase layer in which the target product is dissolved;

(3) treating the above-mentioned organic phase layer with a decolorizing adsorbent;

(4) Filtrate and separate while hot to remove insolubles such as decolorizing adsorbent, thalline, organic salt;

(5) the dicarboxylic acid product is transferred from the organic phase to the aqueous phase by back extraction;

(6) acid analysis from the resulting aqueous phase to obtain long-chain dicarboxylic acid crystals;

(7) Separating and drying the above crystals to obtain dicarboxylic acid products.

The specific steps of the above two schemes are described in detail below.

The method for separating and removing unconverted n-alkanes can be:

Heating the terminated fermentation broth after fermentation to 80-100°C, and then standing still, so that unconverted alkanes and fermentation broth are layered, the upper layer is alkane, the lower layer is fermentation broth and bacteria, and the upper layer of alkane is separated.

The extraction step can be carried out as follows:

Add an extraction solvent to the fermented liquid after the alkane is separated, and heat to 80-100° C. for extraction under stirring, so that the dicarboxylic acid is transferred from the fermented liquid to the solvent phase. In order to reduce the solubility of the dicarboxylic acid in the water phase, make the extraction more complete, and reduce the emulsification, adjust the pH value of the fermentation broth with an inorganic acid (such as sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, etc.) that is stronger than the dicarboxylic acid. Make it reach 4.5～3.0, then stand and stratify under heat preservation, the upper layer is the solvent phase with dicarboxylic acid dissolved, the lower layer is the water phase layer, the bacteria stay in the water phase layer, and then separate to obtain the solvent phase. In order to extract completely, two or more extraction methods can also be used, and then the solvent phases of the two or more extractions are combined.

In the above extraction process, the extraction temperature should preferably not exceed 100°C, preferably 85-90°C, and the stirring speed should preferably be kept at 20-50r/min.

When adjusting the pH value, the concentration of the inorganic acid is preferably 5-10N.

For the solvent used, it should have the following properties:

(1) It is immiscible with water, and at high and low temperatures, the solubility of water in solvents and the solubility of solvents in water are both small;

(2) The solubility of dicarboxylic acid is large at high temperature, but the solubility is small at low temperature;

(3) Do not chemically react with dicarboxylic acid under operating conditions;

(4) The price is low or moderate, and the safety factor is large.

Such organic solvents include ketone solvents, such as methyl isobutyl ketone, methyl ethyl ketone, etc., or one or more of ester solvents such as butyl acetate, isobutyl acetate, etc.

The amount of organic solvent used is determined according to the dicarboxylic acid content in the fermented liquid, so that the dicarboxylic acid in the fermented liquid can be completely dissolved or slightly more, usually fermented liquid: solvent (v/v)=1: 0.5-1.2, preferably 1:0.6-0.8.

The process of decolorizing adsorbent to treat the organic phase layer can be:

Add an appropriate amount of decolorizing adsorbent to the solvent phase obtained in the above process to remove impurities such as organic pigments and soluble proteins dissolved in the solvent, keep the temperature at 90-120°C, and perform decolorization and adsorption under stirring conditions for at least 1 hour , preferably for 1 to 2 hours, and then filtered while hot to remove the decolorizing adsorbent, a small amount of bacteria and some insoluble impurities entrained in the solvent to obtain a colorless and transparent organic solution containing dicarboxylic acid. The operating temperature of the separation process is preferably kept at 90-100°C.

The decolorizing adsorbent is activated carbon or activated clay with a porous structure, and the activated carbon is preferably macroporous powdered activated carbon. For activated clay, the requirement is that the water content is 5.0-10.0%, preferably 6.5-8.0%, and the particle size is more than 95% of the 120-mesh sieve. The amount of the decolorizing adsorbent is determined according to the color depth of the solvent phase, usually 1.0-6.5%, preferably 3.0-5.5%.

The back extraction step can adopt the following method: in the organic hot solvent containing dicarboxylic acid obtained in the above steps, add 1.2 to 2 times the volume of hot water (temperature 80 to 90 ° C) under low speed stirring, and use 6 to 10N NaOH solution to carry out Alkalizing, making the pH value of the water phase reach 9-12, and lowering the temperature to room temperature, so that the dicarboxylic acid in the solvent phase is transferred to the water phase, and standing to separate layers. The upper layer is a solvent that can be directly returned for next use, and the lower layer is an aqueous phase layer containing dicarboxylic acid sodium salt.

The hot water used for stripping is best to use purified pure water. Poor water quality will form metal salts of dicarboxylic acid during the treatment process, which will remain in the product and affect the performance of the product.

The acid analysis step can refer to the following method:

Heat the sodium salt solution of the above-mentioned dicarboxylic acid to 80-95°C, add 2-8N inorganic acid (such as sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, etc.) Carboxylic acid exists in free form. Then control the cooling rate to cool down slowly, stir at a low speed, the cooling rate can be 3-15°C/h, and the rotation speed can be 20-50r/min, so that the dicarboxylic acid crystallizes out of the solution, and keep it for 5-10 hours after cooling down to room temperature , in order to facilitate the formation of good crystal morphology.

The above-mentioned crystals can be separated by methods such as filtration or centrifugation to separate the dicarboxylic acid from the crystallization liquid to obtain wet crystals.

The wet crystals of dicarboxylic acid are dried at a drying temperature of <100°C, preferably 50-70°C. After drying, the refined α, ω-long-chain dicarboxylic acid product is obtained, and its appearance is white powder.

The α, ω-long-chain dicarboxylic acid refers to C ₁₁ ~ C ₁₈ straight chain aliphatic dicarboxylic acid, the molecular formula is HOOC (CH ₂ ) _n COOH (n = 9 ~ 16), which can be a single component The dicarboxylic acid can also be a mixed dicarboxylic acid of any composition and any proportion. The content of dicarboxylic acid in the fermentation liquid is 20-180 g/l.

Compared with the prior art, the present invention has the following advantages:

(1) Due to the extraction of the whole fermentation broth, the product is directly extracted from the fermentation broth, which saves the pretreatment processes such as acidification crystallization, filtration, and drying, simplifies the process steps, shortens the operation cycle, and reduces energy consumption;

(2) The decolorization and adsorption step removes impurities such as organic pigments and soluble proteins in the solvent, which can ensure the purity of the dicarboxylic acid product obtained in the subsequent treatment process, and can make the recovered solvent light in color and less in impurities. Return for reuse, eliminating the need for lengthy solvent regeneration procedures.

(3) Since the latter steps are all carried out in the water phase, it is easy to operate and improves the working environment and operational safety;

(4) The product is directly crystallized from the water phase, which reduces solvent consumption and air pollution, and water has a low boiling point and is easy to volatilize, which is convenient for reducing drying energy consumption and shortening drying time, and there is no residual solvent in the product.

The invention has the advantages of simple technological process, low energy consumption and low product cost, and is beneficial to mass industrial production.

Example 1

Take 400ml of terminated fermentation broth with n-tridecane as substrate, wherein the content of tridecanedioic acid is 96g/l, heat to 90-100°C under stirring, then let stand to separate and remove unconverted alkanes. Add 240ml of butyl acetate, heat to 90-95°C under stirring (stirring speed 40-50r/min), add 6N H ₂ SO ₄ dropwise, adjust the pH value of the fermentation broth to about 4.0, let it stand under heat preservation layer, separating the upper and lower two-phase layers. Add 100-120 ml of butyl acetate to the water phase layer with bacteria cells in the lower layer, extract once more, and combine the solvent phases extracted twice. Add 13g of powdered activated carbon, heat to about 100°C under stirring, decolorize and adsorb for 1.5h, and then heat filter under heat preservation. Add 400ml of pure water at 70 to 80°C to the obtained hot filtrate while continuing to keep warm, adjust the pH of the water phase to 10 with about 6N NaOH solution, let the layers stand and cool to room temperature, and remove the upper solvent for next time use. Add 4N H ₂ SO ₄ dropwise to the lower aqueous layer under stirring (stirring speed 25r/min) to adjust the pH value to 4.0-3.0, and heat to about 90°C to make the solution clear. Then the temperature is controlled to cool down to room temperature, and the cooling rate is about 5-10°C/h. During the cooling process, the dicarboxylic acid product slowly precipitates from the solution in the form of crystals. After filtration, the dicarboxylic acid filter cake is obtained, and dried at 60°C to obtain white powder tridecanedioic acid. The product yield is 96.1%, and the purity is 95.6%, total acid content >99.0%.

Example 2

Take 400ml of terminated fermentation broth with n-tridecane as substrate, wherein the content of tridecanedioic acid is 127g/l, heat to 90°C under stirring, let stand to separate layers, and separate unconverted n-tridecane . 320ml and 140ml of methyl isobutyl ketone were added respectively for two extractions. Compared with Example 1, except that there is no decolorization and adsorption step, other operating steps and conditions are the same. The appearance of the obtained product is white powder, the recovery rate of tridecanedioic acid is 97.4%, the purity is 96.3%, and the total acid content is >99.0%.

Embodiment 3～4

Take respectively hexadecanedioic acid and _C12 ～ _C16 mixed dicarboxylic acids (the composition is: _C12 dicarboxylic acid 6.8%, _C13 dicarboxylic acid 41.7%, _C14 dicarboxylic acid 38.5%, _C15 Dicarboxylic acid 9.2%, C ₁₆ dicarboxylic acid 3.6%) terminated fermented liquid extracts, solvent is butyl acetate, and decolouring adsorbent is gac, operation steps and method are with embodiment 1, and operation condition is listed in table 1, implements The results are listed in Table 2.

Table 1 Example Volume of fermentation broth ml product Acid content g/l Solvent addition amount ml Adding amount of decolorizing adsorbent g 3 500 C ₁₆ dicarboxylic acid 96 450 16 4 500 C ₁₂ ～C ₁₆ mixed dicarboxylic acids 105 (total acid) 500 twenty one

Table 2 Example Product purity% Total acid content% Exterior 95% ethanol solution Product Recovery % 3 95.8 >99.0 White powder Colorless and transparent 96.4 4 >99.0 White powder Colorless and transparent 95.0

Claims (7)

1. one kind is extracted refining α, ω-C from fermented liquid ₁₁～C ₁₈The method of straight chain aliphaticdicarboxylic acid comprises following step:

(1) unconverted normal paraffin is removed in separation from stop fermented liquid;

(2) handle (1) step gained with organic solvent extraction and contain α, ω-C ₁₁～C ₁₈The fermented liquid of straight chain aliphaticdicarboxylic acid and thalline obtains being dissolved with the organic layer of purpose product;

(3) insoluble impurities of carrying secretly in thalline and the solvent phase is removed in the filtered while hot separation;

(4) with the reextraction method dicarboxylic acid product is transferred to aqueous phase from organic phase;

(5) obtain C from gained aqueous phase acid out ₁₁～C ₁₈The crystallisate of straight chain aliphaticdicarboxylic acid;

(6) separation, dry above-mentioned crystallisate obtain dicarboxylic acid product.

2. according to described refining α, the ω-C of from fermented liquid, extracting of claim 1 ₁₁～C ₁₈The method of straight chain aliphaticdicarboxylic acid is characterized in that in described extraction process, and behind the adding extraction agent, the pH value of regulating fermented liquid is in 3.0～4.5 scope.

3. according to described refining α, the ω-C of from fermented liquid, extracting of claim 1 ₁₁～C ₁₈The method of straight chain aliphaticdicarboxylic acid is characterized in that described extraction agent is one or more in methyl iso-butyl ketone (MIBK), butanone, N-BUTYL ACETATE, the isobutyl acetate.

4. one kind is extracted refining α, ω-C from fermented liquid ₁₁～C ₁₈The method of straight chain aliphaticdicarboxylic acid comprises following step:

(1) unconverted normal paraffin is removed in separation from stop fermented liquid;

(2) contain α, ω-C with the organic solvent processing ₁₁～C ₁₈The fermented liquid of straight chain aliphaticdicarboxylic acid and thalline obtains being dissolved with the organic layer of purpose product;

(3) handle above-mentioned organic layer with decolorizing adsorbent;

(4) insolubless such as decolorizing adsorbent, thalline, organic salt are removed in the filtered while hot separation;

(5) with the reextraction method dicarboxylic acid product is transferred to aqueous phase from organic phase;

(6) obtain C from gained aqueous phase acid out ₁₁～C ₁₈The crystallisate of straight chain aliphaticdicarboxylic acid;

(7) filtration, dry above-mentioned crystallisate obtain dicarboxylic acid product.

5. according to described refining α, the ω-C of from fermented liquid, extracting of claim 4 ₁₁～C ₁₈The method of straight chain aliphaticdicarboxylic acid is characterized in that in described extraction process, and behind the adding extraction agent, the pH value of regulating fermented liquid is in 3.0～4.5 scope.

6. according to described refining α, the ω-C of from fermented liquid, extracting of claim 4 ₁₁～C ₁₈The method of straight chain aliphaticdicarboxylic acid is characterized in that described extraction agent is one or more in methyl iso-butyl ketone (MIBK), butanone, N-BUTYL ACETATE, the isobutyl acetate.

7. according to described refining α, the ω-C of from fermented liquid, extracting of claim 4 ₁₁～C ₁₈The method of straight chain aliphaticdicarboxylic acid is characterized in that described decolorizing adsorbent is gac or the atlapulgite with vesicular structure.