CN109485558B

CN109485558B - Purification method of long-chain dibasic acid

Info

Publication number: CN109485558B
Application number: CN201710808852.7A
Authority: CN
Inventors: 李晓姝; 高大成; 张霖; 师文静; 樊亚超; 王鹏翔; 孙启梅
Original assignee: China Petroleum and Chemical Corp; Sinopec Dalian Research Institute of Petroleum and Petrochemicals
Current assignee: Sinopec Dalian Petrochemical Research Institute Co ltd; China Petroleum and Chemical Corp
Priority date: 2017-09-09
Filing date: 2017-09-09
Publication date: 2021-02-05
Anticipated expiration: 2037-09-09
Also published as: CN109485558A

Abstract

The invention relates to a purification method of long-chain dibasic acid, which comprises the following steps of I, heating terminated fermentation liquor for demulsification, and filtering to obtain fermentation clear liquid; II. Adjusting the pH value of the fermentation clear liquid to acidity while stirring, adjusting the pH value to alkalinity, adding a small amount of surfactant, stirring for a period of time, and filtering to remove solid matters; III, adding active carbon, stirring, decoloring and filtering; IV, heating and acidifying the clear liquid obtained in the step III, and then cooling, filtering and drying to obtain a long-chain dicarboxylic acid product. According to the invention, the nitrogen content in the biological method long-chain dibasic acid product is effectively reduced by the synergistic action of the acid, the alkali and the surfactant, and the high-quality dibasic acid product can be obtained.

Description

Purification method of long-chain dibasic acid

Technical Field

The invention belongs to the technical field of biochemical engineering, and particularly relates to a method for purifying long-chain dibasic acid, in particular to a method for obtaining high-purity long-chain dibasic acid from microbial fermentation liquor.

Background

The molecular general formula of the long-chain dibasic acid is C_nH_2n-2O₄Wherein n is 10-18, and is a metabolite obtained by fermenting microorganisms with liquid wax or the like. The fermentation liquor is a complex multiphase system containing unreacted carbon source and microbial cellsAnd fragments, unused culture medium and metabolites, secretion of microorganisms and the like, particularly, a large amount of impurities such as protein, pigment, ash and the like are contained in the culture medium, so that the purity and the application of the product are seriously influenced, and the extraction and the refining of the dibasic acid are difficult.

The existing methods for extracting the long-chain dicarboxylic acid are generally divided into a solvent method and a water phase method. Although the solvent method can solve the above problems, the solvent method has a great limitation in use due to large investment, severe corrosion of equipment, residual solvent and alkane in the product, production safety and environmental pollution. Although the traditional aqueous phase purification method overcomes the defects of a solvent method, the product purity and yield can not reach higher indexes.

In the refining method of long-chain dicarboxylic acid disclosed in patent CN01142806.6, long-chain dicarboxylic acid is refined by using dry powder of long-chain dicarboxylic acid as raw material and acetone, methanol and ethanol as solvents. Firstly, adsorbing dibasic acid in fermentation liquor by active carbon, then acidifying, crystallizing, filtering, washing and drying dibasic acid crystal filter cakes to obtain long-chain dibasic acid dry powder, and then refining by adopting an organic solvent. The used alcohol solvent is a common solvent with low price, has certain effect on the purification of the crude long-chain dicarboxylic acid, but can generate esterification reaction with the raw material dicarboxylic acid to generate a small amount of ester byproducts, thereby having certain influence on the quality of the long-chain dicarboxylic acid of a final product and the polymerization performance of the product. In addition, although the adsorbent can meet the requirement of decolorization, the removal effect of nitrogen-containing impurities such as protein is still limited.

Patent CN103030550A adopts multiple acidification, filtration, washing long chain dibasic acid crude product, puts DCn filter cake in water, heats to above the DCn melting point under high pressure, keeps warm for a period of time, cools down, filters to obtain long chain dibasic acid crystal, the product monoacid purity reaches more than 98.5%. However, the method only adopts the means of filtering and multiple acidification and dilution for water-soluble protein and other impurities in the fermentation liquor, the removal effect is limited, the system is heated to high temperature before crystallization to promote the oxidation and denaturation of pigments, proteins and the like, the impurities are adsorbed in the crystal product along with the reduction of the temperature, and the color and the nitrogen content of the product are influenced to a certain extent.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a method for purifying long-chain dicarboxylic acid. According to the invention, the nitrogen content in the biological method long-chain dibasic acid product is effectively reduced by the synergistic action of the acid, the alkali and the surfactant, and the high-quality dibasic acid product can be obtained.

The purification method of the long-chain dicarboxylic acid comprises the following steps:

I. heating the terminated fermentation liquor for demulsification, and filtering to obtain fermentation clear liquid;

II. Adjusting the pH value of the fermentation clear liquid to acidity while stirring, adjusting the pH value to alkalinity, adding a small amount of surfactant, stirring for a period of time, and filtering to remove solid matters;

III, adding active carbon, stirring, decoloring and filtering;

IV, heating and acidifying the clear liquid obtained in the step III, and then cooling, filtering and drying to obtain a long-chain dicarboxylic acid refined product.

In the method, the fermentation stopping liquid in the step I is a metabolite obtained by fermenting microorganisms by using liquid wax or alkane, wherein the long-chain dibasic acid contained in the fermentation stopping liquid has a molecular general formula C_nH_2n-2O₄Wherein n is 10-18, and the long-chain dibasic acid is a single long-chain dibasic acid or a mixed long-chain dibasic acid.

In the method, the heating demulsification mode in the step I is a heating demulsification mode conventionally used in the field, for example, demulsification is carried out at 70-100 ℃, standing is carried out to room temperature, residual alkane on the upper layer is removed, and then bacteria are removed by filtering. Further preferred is the following: heating the terminated fermentation liquor to 85-100 ℃, standing for 1-2 h, and then separating unreacted alkane; and cooling to 60-75 ℃, and filtering to remove impurities such as thalli and the like to obtain a fermentation clear liquid.

In the method of the present invention, conventional methods and apparatuses such as centrifugation or filtration can be used in step I.

In the method, acid is slowly added while stirring to adjust the pH value of the fermentation clear liquid to acidity, and the added acid can be inorganic acid with any concentration, such as at least one of hydrochloric acid, sulfuric acid, nitric acid and the like, preferably sulfuric acid; adjusting the pH value of the fermentation clear liquid to 3.0-5.5, preferably 4.0-5.0.

In the method, after the pH value is adjusted to be acidic, slowly adding alkali to adjust the pH value to be alkaline, wherein the added alkali can be inorganic alkali with any concentration, such as at least one of sodium hydroxide, potassium hydroxide, calcium hydroxide and the like, and preferably sodium hydroxide; the pH value is adjusted to 8.0-11, preferably 8.0-9.5. Adding acid to the specified pH value, then continuously stirring for 10-60 min, then adding alkali to adjust the pH value, adding alkali to the specified pH value, then continuously stirring for 10-60 min, and then adding a surfactant.

In the method of the present invention, the surfactant in step II is an ionic surfactant or a nonionic surfactant, preferably at least one of sodium dodecyl sulfate in the ionic surfactant, sodium dodecyl sulfate, or fatty alcohol-polyoxyethylene ether in the nonionic surfactant, and more preferably isomeric tridecanol polyoxyethylene ether. The addition amount of the surfactant is 1-100 g, preferably 5-20 g, per liter of fermentation clear liquid, and the filtration is carried out after the surfactant is added and the stirring is continued for 1-4 h.

Further, after adjusting the pH value to acidity by adding an acid, an amount of at least one of urea, guanidine hydrochloride, guanidine isothiocyanate, etc., preferably guanidine isothiocyanate, is added. The addition amount of the urea and the guanidine hydrochloride is 0.5-50 g, preferably 3-15 g, added in each liter of fermentation clear liquid. And stirring for 10-60 min after adding, and then adding alkali to adjust the pH value to be alkaline.

In the method, the filtration in the step II can be carried out by ultrafiltration, nanofiltration or microfiltration and the like, and the clear liquid is obtained after solid matters are removed.

In the method, the amount of the activated carbon added in the step III accounts for 0.3-1.5% of the volume of the clear liquid, and the decoloring time is 20-120 min, preferably 30-60 min.

In the method, the heating temperature in the step IV is 80-95 ℃, the acidification pH value is 2.0-4.0, and stirring is carried out in the acidification process. The acid used for acidification may be any concentration of H₂SO₄、HNO₃HCl or H₃PO₄And the like.

In the method of the present invention, the cooling temperature is generally 10 to 30 ℃ until the long-chain dicarboxylic acid is sufficiently crystallized. The drying temperature is 105-110 ℃, and the drying time is 4-6 h.

The method can obtain high-purity single long-chain dicarboxylic acid products and can also obtain mixed long-chain dicarboxylic acid products.

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

(1) the inventor finds that although the long-chain dicarboxylic acid terminated fermentation liquor is subjected to heating treatment, because the long-chain dicarboxylic acid fermentation liquor prepared by a biological method contains a large amount of thalli, the heating and alkali adding method mainly plays roles in demulsification and breaking of thalli cells in the traditional pretreatment process so as to achieve the aims of recovering alkane and improving yield. Along with the cell wall breakage, a large amount of water-soluble biomolecules such as protein, nucleic acid and the like in the thalli are released into fermentation liquor and are difficult to remove along with subsequent means such as filtration, adsorption and the like, and a large amount of impurities exist in a water phase, so that the important reason that the product quality, particularly the nitrogen content does not reach the standard is caused. The invention firstly adjusts the pH value of the fermented clear liquid after demulsification and three-phase separation to be acidic, then adds alkali to be alkaline, and adds surfactant under alkaline condition, thus strengthening the denaturation and precipitation effects of protein, nucleic acid and other biomolecules in the fermented clear liquid, and further obviously improving the removal rate of nitrogen.

(2) According to the invention, the fermentation clear liquid is adjusted to be acidic, reagents such as urea, guanidine hydrochloride and guanidine isothiocyanate are added under the acidic condition, then alkali is added to adjust the pH value to be alkaline, and the surfactant is added under the alkaline condition, so that the deformation and precipitation effects are further enhanced, and the nitrogen removal rate is further improved.

(3) The method has the characteristics of simple process, easy realization, environmental friendliness, high product yield, good quality and the like.

Detailed Description

The method and effects of the present invention will be described in detail below with reference to examples, but the scope of the present invention is not limited to the following examples. In the present invention, wt% is a mass fraction.

The total acid purity was titrated with sodium hydroxide standard solution with phenolphthalein as the indicator. The method specifically comprises the following steps: weighing 0.5g of sample (accurate to 0.0002 g) and placing the sample in a 250mL conical flask, adding 30mL of ethanol solution, adding 2 drops of phenolphthalein indicator after the sample is completely dissolved, dropping the solution to reddish with sodium hydroxide standard titration, and keeping the color unchanged for 30 s. Calculated as X (%) = cxv × 0.115 × 100%/m, wherein: the weight percentage of the X-diacid is percent; c-actual concentration of sodium hydroxide standard titration solution, mol/L; v-the volume of the sodium hydroxide standard titration solution consumed by titration, mL; 0.115-dibasic acid mass in grams equivalent to 1.00mL sodium hydroxide standard titration solution [ c (NaOH) =1.000mol/L ]; m-sample mass, g.

The purity of the monoacid is detected by gas chromatography, according to the standard method GB5413.27-2010 determination of fatty acids in infant food and dairy products.

The total nitrogen adopts a chemiluminescence method, and a boat sample injection chemiluminescence method is determined by referring to the standard NB/SH/T0704-2010 petroleum and petroleum products.

Example 1

N-dodecane is used as a substrate, and the Candida tropicalis is used for producing the dodecanedioic acid by fermentation. The concentration of the dodecanedioic acid at the end of the fermentation was 150g/L, and the pH was 7.0. Taking 1000ml of fermentation liquor, heating to 90 ℃, standing to room temperature, removing residual alkane on the upper layer, filtering to remove thalli, and obtaining fermentation clear liquid. Slowly adding 6mol/L sulfuric acid into the fermented clear liquid while stirring to adjust the pH value to 5.0, continuously stirring for 30min, then adding 10mol/L sodium hydroxide solution into the fermented clear liquid while stirring to adjust the pH value to 8.0, continuously stirring for 30min, then adding 5g sodium dodecyl sulfate into the clear liquid, and continuously stirring for 60 min. With a membrane pore size of 10^-2The precipitate was removed by filtration through a μm filter. Adding 5g of activated carbon into the filtered clear liquid, stirring and decolorizing for 20min, and using a membrane with the pore diameter of 10^-2The solid was removed by filtration through a filter of μm. Adjusting the pH of the clear solution to 3.0 with 6mol/L sulfuric acid under stirring, and heating the system to 85 ℃ for heating and acidification. Slowly cooling the system to room temperature until the long-chain dicarboxylic acid is fully crystallized. Filtering to obtain a long-chain dicarboxylic acid filter cake, and drying the filter cake at 105 ℃ for 6h to obtain the product. The product quality is shown in Table 1.

Example 2

The tridecane is used as a substrate, and the Candida tropicalis is utilized to ferment and produce the tridecane dibasic acid. The concentration of the thirteen-carbon dibasic acid at the end of the fermentation is 145g/L, and the pH value is 7.2. Taking 1000ml of fermentation liquor, heating to 95 ℃, standing to room temperature, removing residual alkane on the upper layer, filtering to remove thalli, and obtaining fermentation clear liquid. Slowly adding 8mol/L nitric acid into the fermented clear liquid while stirring to adjust the pH value to 4.0, continuously stirring for 20min, then adding 10mol/L potassium hydroxide solution into the fermented clear liquid while stirring, adjusting the pH value to 9.0, continuously stirring for 20min, then adding 15g isomeric tridecanol polyoxyethylene ether into the clear liquid, and continuously stirring for 3 h. With a membrane pore size of 10^-2The precipitate was removed by filtration through a μm filter. Adding 10g of active carbon into the filtered clear liquid, stirring and decolorizing for 60min, and using a membrane with the pore diameter of 10^-2The solid was removed by filtration through a filter of μm. Adjusting the pH of the clear solution to 2.0 by using 6mol/L sulfuric acid under the stirring condition, and heating the system to 85 ℃ for heating and acidifying. Slowly cooling the system to room temperature until the long-chain dicarboxylic acid is fully crystallized. Filtering to obtain a long-chain dicarboxylic acid filter cake, and drying the filter cake at 110 ℃ for 4h to obtain the product. The product quality is shown in Table 1.

Example 3

The tetradecanoic acid is produced by taking n-tetradecane as a substrate and utilizing candida tropicalis to ferment. The tetradecanedioic acid concentration at the end of fermentation is 135g/L, and the pH is 7.4. Taking 1000ml of fermentation liquor, heating to 95 ℃, standing to room temperature, removing residual alkane on the upper layer, filtering to remove thalli, and obtaining fermentation clear liquid. Slowly adding 4mol/L hydrochloric acid into the fermented clear liquid while stirring to adjust the pH value to 4.5, continuously stirring for 40min, then adding 6mol/L sodium hydroxide solution into the fermented clear liquid while stirring to adjust the pH value to 9.5, continuously stirring for 40min, then adding 20g sodium dodecyl sulfate into the clear liquid, and continuously stirring for 2 h. With a membrane pore size of 10^-2The precipitate was removed by filtration through a μm filter. Adding 3g of activated carbon into the filtered clear liquid, stirring and decolorizing for 40min, and using a membrane with the aperture of 10^-2The solid was removed by filtration through a filter of μm. Adjusting the pH of the clear solution to 4.0 by using 6mol/L sulfuric acid under the stirring condition, and heating the system to 95 ℃ for heating and acidifying. Will systemThe temperature is slowly reduced to the room temperature until the long-chain dicarboxylic acid is fully crystallized. Filtering to obtain a long-chain dicarboxylic acid filter cake, and drying the filter cake at 105 ℃ for 5h to obtain the product. The product quality is shown in Table 1.

Example 4

The processing procedure and operating conditions were the same as in example 1. The difference lies in that the fermentation liquor is heated to 90 ℃, kept stand for 1h, and then unreacted alkane is separated; then the temperature is reduced to 70 ℃, and impurities such as thalli and the like are filtered to obtain fermentation clear liquid. The product quality is shown in Table 1.

Example 5

The processing procedure and operating conditions were the same as in example 1. Except that the pH of the fermentation broth was adjusted to 5.5. The product quality is shown in Table 1.

Example 6

The processing procedure and operating conditions were the same as in example 1. Except that the pH of the fermentation broth was adjusted to 3.0. The product quality is shown in Table 1.

Example 7

The processing procedure and operating conditions were the same as in example 1. Except that after adjusting to acidity, alkali was added to adjust to pH 11. The product quality is shown in Table 1.

Example 8

The processing procedure and operating conditions were the same as in example 1. The difference is that the added surfactant is isomeric tridecanol polyoxyethylene ether. The product quality is shown in Table 1.

Example 9

The processing procedure and operating conditions were the same as in example 1. Except that the amount of the surfactant added was 100 g. The product quality is shown in Table 1.

Example 10

The processing procedure and operating conditions were the same as in example 1. The difference is that after the pH value is adjusted to be acidic by adding acid, 15g of urea is added into each liter of fermentation clear liquid, and the mixture is stirred for 30min after the addition. The product quality is shown in Table 1.

Example 11

The processing procedure and operating conditions were the same as in example 1. The difference is that 10g of guanidine hydrochloride is added into each liter of fermentation clear liquid after the pH value is adjusted to be acidic by adding acid, and the mixture is stirred for 30min after the addition. The product quality is shown in Table 1.

Example 12

The processing procedure and operating conditions were the same as in example 1. Except that 7mL of guanidine isothiocyanate (4 mol/L) was added to each liter of the fermentation supernatant after adjusting the pH to acidity by adding acid, and the mixture was stirred for 30min after the addition. The product quality is shown in Table 1.

Example 13

The processing procedure and operating conditions were the same as in example 1. Except that after the pH value was adjusted to acidity by adding acid, 8mL of 6mol/L guanidine isothiocyanate was added per liter of the fermentation supernatant, followed by stirring for 30 min. The product quality is shown in Table 1.

Example 14

The processing procedure and operating conditions were the same as in example 1. Except that after the pH value was adjusted to acidity by adding acid, 1mL of 8mol/L guanidinium isothiocyanate was added per liter of the fermentation supernatant, followed by stirring for 30 min. The product quality is shown in Table 1.

Example 15

The processing procedure and operating conditions were the same as in example 1. Except that after adding alkali to adjust the pH value to be alkaline, 1mL of 8mol/L guanidinium isothiocyanate was added to each liter of the fermentation supernatant, and the mixture was stirred for 30min after the addition. The product quality is shown in Table 1.

Comparative example 1

The processing procedure and operating conditions were the same as in example 1. The difference is that the pH value is adjusted to be alkaline after adding acid, and the surfactant is directly added. The product quality is shown in Table 1.

Comparative example 2

The processing procedure and operating conditions were the same as in example 1. The difference is that the acidity is not adjusted, and the surfactant is added after the alkalinity is directly adjusted. The product quality is shown in Table 1.

Comparative example 3

The processing procedure and operating conditions were the same as in example 1. Except that no surfactant was added. The product quality is shown in Table 1.

Comparative example 4

The processing procedure and operating conditions were the same as in example 1. The difference lies in that the order of adjusting acid and alkali is changed. The product quality is shown in Table 1.

Comparative example 5

The processing procedure and operating conditions were the same as in example 1. Except that the purification was carried out by the method described in CN 01142806.6. The product quality is shown in Table 1.

Comparative example 6

The processing procedure and operating conditions were the same as in example 1. Except that the purification was carried out by the method described in CN 103030550A. The product quality is shown in Table 1.

TABLE 1 Long chain dibasic acid product quality

Compared with the comparative examples, the method disclosed by the invention has the advantages that the nitrogen content is effectively reduced while the product purity is ensured through the sequential synergistic effect of the acid, the alkali and the surfactant, and the high-quality dibasic acid product can be obtained. Particularly, after the pH value is adjusted to be acidic by adding acid, a certain amount of urea, guanidine hydrochloride, guanidine isothiocyanate and the like are added, so that the product quality can be further optimized. The nitrogen content is significantly reduced compared to the prior art.

Claims

1. The method for purifying the long-chain dicarboxylic acid is characterized by comprising the following steps of:

I. heating the terminated fermentation liquor for demulsification, and filtering to obtain fermentation clear liquid; the fermentation stopping liquid is a metabolite obtained by fermenting liquid wax or alkane by microorganisms, and the molecular general formula of the contained long-chain dibasic acid is C_nH_2n-2O₄N is 10-18;

II. Adding inorganic acid while stirring to adjust the pH value of the fermentation clear liquid to 3.0-5.5; adding alkali to adjust the pH value to 8.0-11; then adding a surfactant, wherein the surfactant is at least one of sodium dodecyl sulfate, sodium dodecyl sulfate or fatty alcohol-polyoxyethylene ether, the addition amount of the surfactant is 1-100 g per liter of fermentation clear liquid, stirring for a period of time, and filtering to remove solid matters;

III, adding active carbon, stirring, decoloring and filtering;

2. The method of claim 1, wherein: and the heating demulsification in the step I is demulsification at 70-100 ℃, standing to room temperature, removing residual alkane on the upper layer, and filtering to remove thalli.

3. The method of claim 1, wherein: heating the terminated fermentation liquor to 85-100 ℃, standing for 1-2 h, and then separating unreacted alkane; and cooling to 60-75 ℃, and filtering to remove thallus impurities to obtain a fermentation clear liquid.

4. The method of claim 1, wherein: and II, stirring and slowly adding acid to adjust the pH value of the fermentation clear liquid to 4.0-5.0.

5. The method of claim 1, wherein: and II, after the pH value is adjusted to be acidic, slowly adding inorganic base to adjust the pH value to 8.0-9.5.

6. The method of claim 1, wherein: and the addition amount of the surfactant in the step II is 5-20 g per liter of fermentation clear liquid.

7. The method of claim 1, wherein: after adding acid to adjust the pH value to be acidic, adding a certain amount of at least one of urea, guanidine hydrochloride and guanidine isothiocyanate, stirring for 10-60 min, and then adding alkali to adjust the pH value to be alkaline.

8. The method of claim 7, wherein: the adding amount of the urea, the guanidine hydrochloride and the guanidine isothiocyanate is 0.5-50 g per liter of fermentation clear liquid.

9. The method of claim 8, wherein: the adding amount of the urea, the guanidine hydrochloride and the guanidine isothiocyanate is 3-15 g per liter of fermentation clear liquid.

10. The method of claim 1, wherein: and (3) the amount of the activated carbon added in the step (III) accounts for 0.3-1.5% of the volume of the clear liquid, and the decoloring time is 20-120 min.

11. The method of claim 1, wherein: step IV, heating at the temperature of 80-95 ℃, and acidifying at the pH value of 2.0-4.0; the acid used for acidification is H of any concentration₂SO₄、HNO₃HCl or H₃PO₄At least one of (1).

12. The method of claim 1, wherein: the cooling temperature in the step IV is to ensure that the long-chain dicarboxylic acid is fully crystallized; the drying temperature is 105-110 ℃, and the drying time is 4-6 h.