Method for refining long-chain dicarboxylic acid in water phase and long-chain dicarboxylic acid

Abstract

The invention provides a method for refining long-chain dibasic acid in a water phase and long-chain dibasic acid, and the method comprises the following steps: S10, placing a long-chain dibasic acid crude product, an oxidizing agent and acid in a reactor, sealing the reactor, raising the temperature in the reactor to 100-160 DEG C, and keeping the temperature for 0.1-3.0 hours, the oxidizing agent being one or two of ozone and hydrogen peroxide; the acid is any one or more of sulfuric acid, hydrochloric acid and phosphoric acid; and S20, cooling and crystallizing the material in the reactor, carrying out solid-liquid separation to obtain a crystal substance, washing the crystal substance with deionized water, and drying the washed crystal substance to obtain a refined long-chain dicarboxylic acid product. According to the method disclosed by the invention, impurities such as protein are partially hydrolyzed by a method of combining high-temperature acid hydrolysis and oxidation, so that the impurities are easily dissolved in water and are removed, meanwhile, the impurities such as pigment and the like are more thoroughly oxidized and removed, and a high-purity long-chain dicarboxylic acid water-phase crystallization product can be obtained while the process flow is simplified.

Description

Technical Field

[0001] The invention relates to a method for extracting and purifying a long-chain dibasic acid, and in particular to a method for refining a long-chain dibasic acid in an aqueous phase and the long-chain dibasic acid prepared by the method. Background Art

[0002] The membrane clear liquid of the long-chain dibasic acid fermentation broth contains a variety of organic impurities such as miscellaneous proteins and pigments. Although the organic solvent crystallization method has excellent products, the environmental pollution and high equipment investment costs are very high. Therefore, the aqueous phase extraction and purification of long-chain dibasic acids has become the focus of research in the industry. Although the existing aqueous phase crystallization production process has undergone a series of complex operations such as activated carbon decolorization or ultrafiltration membrane impurity removal or atmospheric pressure oxidation decolorization or aqueous phase melt crystallization impurity removal, the long-chain dibasic acid product obtained after the final acidification still contains a large amount of protein and pigment impurities, and the product quality is unstable. Summary of the invention

[0003] In view of the defects in the prior art, the purpose of the present invention is to provide a method for refining long-chain dibasic acids in an aqueous phase and the long-chain dibasic acids obtained by the method, wherein the method for refining long-chain dibasic acids in an aqueous phase partially hydrolyzes impurities such as proteins by a method of high-temperature acid hydrolysis and oxidation to make them soluble in water and thus be removed, and at the same time more thoroughly oxidizes and removes impurities such as pigments, thereby simplifying the process flow and obtaining a high-purity long-chain dibasic acid aqueous phase crystalline product.

[0004] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solution:

[0005] According to a first aspect of the present invention, there is provided a method for refining a long-chain dibasic acid in an aqueous phase, comprising the following steps:

[0006] S10, placing the crude long-chain dibasic acid, an oxidant and an acid in a reactor, sealing the reactor, raising the temperature in the reactor to 100-160° C., and keeping the temperature for 0.1-3.0 hours;

[0007] S20, cooling the material in the reactor to crystallize, performing solid-liquid separation to obtain crystals, and washing the crystals with deionized water;

[0008] S30, drying to obtain a refined long-chain dibasic acid product;

[0009] In step S10, the oxidant is one or both of ozone and hydrogen peroxide, and the amount of the oxidant added is 0.1 to 5.0 wt% of the crude quality of the long-chain dibasic acid; the acid is any one or more of sulfuric acid, hydrochloric acid, and phosphoric acid, and the amount of the acid added is 1 to 10 times the quality of the crude long-chain dibasic acid.

[0010] Preferably, in step S10, the addition amount of the oxidant is 0.5-4.0 wt% or 0.5-3.0 wt% of the mass of the crude long-chain dibasic acid.

[0011] Preferably, in step S10, the addition amount of the acid is 2-8 times or 3-6 times the mass of the crude long-chain dibasic acid.

[0012] Preferably, in step S10, the concentration of the acid is 1-4 mol / L, or 1-3 mol / L, or 1-2 mol / L.

[0013] Preferably, step S10 is specifically: placing the crude long-chain dibasic acid, the oxidant and the acid in a reactor, closing the reactor, turning on the stirring function of the reactor, raising the temperature in the reactor to 100-160 °C, correspondingly increasing the pressure to 0.1-0.62 Mpa, and keeping warm for 0.1-3.0 hours.

[0014] Preferably, in step S20, in the materials in the reactor, the content of the long-chain dibasic acid is 10-50 wt%.

[0015] Preferably, in step S10, the crude long-chain dibasic acid placed in the reactor is derived from any one or more of the following:

[0016] The crude long-chain dibasic acid obtained by directly acidifying the ceramic membrane clear liquid of the long-chain dibasic acid fermentation broth;

[0017] The crude long-chain dibasic acid obtained by acidifying the decarbonized clear liquid obtained after decolorizing the ceramic membrane clear liquid of the long-chain dibasic acid fermentation broth with activated carbon;

[0018] The crude long-chain dibasic acid obtained by acidifying the decarbonized clear liquid obtained after heating and decolorizing the ceramic membrane clear liquid of the long-chain dibasic acid fermentation broth with an oxidant and activated carbon between 100 °C and 160 °C;

[0019] The crude long-chain dibasic acid containing a small amount of bacteria obtained by directly acidifying the long-chain dibasic acid fermentation broth and then removing most of the bacteria by rinsing or centrifugation.

[0020] Preferably, in step S10, the crude long-chain dibasic acid is one or more mixtures of crude decanedioic acid, crude undecanedioic acid, crude dodecanedioic acid, crude tridecanedioic acid, crude tetradecanedioic acid, and crude pentadecanedioic acid.

[0021] Preferably, in step S20, the step of cooling and crystallization is specifically: cooling the long-chain dibasic acid material to 80-90 °C, keeping warm for 0.5-2.0 hours, and then cooling to 60 °C for solid-liquid separation.

[0022] Preferably, the crude long-chain dibasic acid added in step S10 is obtained from the ceramic membrane supernatant of the long-chain dibasic acid fermentation broth through a treatment process including acidification. The acid solution used for acidifying the ceramic membrane supernatant is from the filtrate obtained during the preparation of long-chain dibasic acid by the method of aqueous phase refining of long-chain dibasic acid in the previous batch. The filtrate is obtained by performing solid-liquid separation on the material in step S20 to obtain a liquid, then cooling the temperature of the liquid to room temperature to precipitate some solid heterobasic acid impurities, and then filtering.

[0023] According to the second aspect of the present invention, there is provided a long-chain dibasic acid prepared by using the method for aqueous phase refining of long-chain dibasic acid according to any one of the first aspects of the present invention.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The method for aqueous phase refining of long-chain dibasic acid provided by the present invention has a simpler, more efficient, more environmentally friendly process, better quality and lower cost; it can remove a series of impurities such as pigments and proteins at the same time. Under fully optimized conditions, it can not damage the long-chain dibasic acid itself, and can refine the ceramic membrane supernatant of the long-chain dibasic acid fermentation broth that has not been treated by any purification method into a qualified product in one step, and the product quality is excellent. Specific Embodiments

[0026] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below. Apparently, the described embodiments are some, but not all, of the embodiments of the present application.

[0027] In the examples listed below of the present invention, the pressure in the high-pressure reactor is the saturated vapor pressure of water at this temperature; and in the examples listed below of the present invention, the following test methods are used:

[0028] Determination of monoacid purity: Gas phase normalization method;

[0029] Determination of total nitrogen: Kjeldahl method;

[0030] Transmittance test: Transmittance of a 20 wt% dimethyl sulfoxide solution of long-chain dibasic acid at 440 and 550 nm.

[0031] Example 1

[0032] 750 g of the ceramic membrane clarified liquid of dodecanedioic acid fermentation broth with a content of 8.0 wt% and a pH of 8.5 was acidified with phosphoric acid to obtain 102.0 g of wet crude dodecanedioic acid. 102.0 g of this wet crude dodecanedioic acid, 6.0 g of 30% hydrogen peroxide, and 300 g of phosphoric acid with a concentration of 1.5 mol / L were placed in a 500 ml high-pressure reactor. The reactor was sealed, stirred, and heated to 115 °C, maintained at 115 °C for 60 min, then cooled to 80 °C, held for 1.0 h at 80 °C and then cooled to 60 °C for solid-liquid separation to obtain the crystalline product. The crystalline product was washed with 250 g of deionized water at 60 °C, and then dried at 105 °C to obtain the long-chain dicarboxylic acid product. The quality indexes of the product are shown in Table 1.

[0033] Example 2

[0034] 750 g of the ceramic membrane clarified liquid of dodecanedioic acid fermentation broth with a content of 8.0 wt% and a pH of 8.5 was added with 3.0 g of activated carbon and stirred for adsorption and decolorization at 60 °C for 1.0 h. After solid-liquid separation, it was acidified with sulfuric acid to obtain 100.9 g of wet crude dodecanedioic acid. 100.9 g of this wet crude dodecanedioic acid, 6.0 g of 30% hydrogen peroxide, and 300 g of sulfuric acid with a concentration of 2.0 mol / L were placed in a 500 ml high-pressure reactor. The reactor was sealed, stirred, and heated to 130 °C, maintained at 130 °C for 90 min, then cooled to 80 °C, held for 1.0 h at 80 °C and then cooled to 60 °C for solid-liquid separation to obtain the crystalline product. The crystalline product was washed with 250 g of deionized water at 60 °C, and then dried at 105 °C to obtain the long-chain dicarboxylic acid product. The quality indexes of the product are shown in Table 1.

[0035] Example 3

[0036] 750 g of the ceramic membrane clarified liquid of dodecanedioic acid fermentation broth with a content of 8.0 wt% and a pH of 8.5 was added with 6.0 g of 30% hydrogen peroxide and 1.0 g of activated carbon, and stirred for oxidation at 120 °C for 1.0 h. After cooling to 80 °C for solid-liquid separation, it was acidified with sulfuric acid. After solid-liquid separation of the acidified material, 99.6 g of wet crude dodecanedioic acid was obtained. 99.6 g of this wet crude dodecanedioic acid, 6.0 g of 30% hydrogen peroxide, and 300 g of sulfuric acid with a concentration of 1.5 mol / L were placed in a 500 ml high-pressure reactor. The reactor was sealed, stirred, and heated to 160 °C, maintained at 160 °C for 30 min, then cooled to 80 °C, held for 1.0 h at 80 °C and then cooled to 60 °C for solid-liquid separation to obtain the crystalline product. The crystalline product was washed with 250 g of deionized water at 60 °C, and then dried at 105 °C to obtain the long-chain dicarboxylic acid product. The quality indexes of the product are shown in Table 1.

[0037] Comparative Example 1

[0038] 750 g of the ceramic membrane supernatant of a dodecanedioic acid fermentation broth with a content of 8.0 wt% and a pH of 8.5 was acidified with phosphoric acid to obtain 103.3 g of wet crude dodecanedioic acid. 103.3 g of this wet crude dodecanedioic acid and 300 g of deionized water were placed in a 500 ml high-pressure reactor, adjusted to a pH of 1.0, stirred and heated to 115 °C, maintained at 115 °C for 60 min, then cooled by 1.0 °C every 6 minutes to 80 °C, kept warm for 1.0 hour and then cooled to 60 °C for solid-liquid separation to obtain the crystals. The crystals were washed with 250 g of 60 °C deionized water and dried at 105 °C to obtain the long-chain dicarboxylic acid product. The product quality indicators are shown in Table 1.

[0039] Comparative Example 2

[0040] 750 g of the ceramic membrane supernatant of a dodecanedioic acid fermentation broth with a content of 8.0 wt% and a pH of 8.5 was added with 3.0 g of activated carbon and stirred for adsorption and decolorization at 60 °C for 1.0 hour. After solid-liquid separation, it was acidified with sulfuric acid to obtain 101.2 g of wet crude dodecanedioic acid. 101.2 g of this wet crude dodecanedioic acid and 300 g of deionized water were placed in a 500 ml autoclave, adjusted to a pH of 2.0 with sulfuric acid, stirred and heated to 130 °C, maintained at 130 °C for 90 min, then cooled by 1.0 °C every 6 minutes to 80 °C, kept warm for 1.0 hour and then cooled to 60 °C for solid-liquid separation to obtain the crystals. The crystals were washed with 250 g of 60 °C deionized water and dried at 105 °C to obtain the long-chain dicarboxylic acid product. The product quality indicators are shown in Table 1.

[0041] Comparative Example 3

[0042] 750 g of the ceramic membrane supernatant of a dodecanedioic acid fermentation broth with a content of 8.0 wt% and a pH of 8.5 was added with 6.0 g of 30% hydrogen peroxide and 1.0 g of activated carbon and stirred for oxidation at 120 °C for 1.0 hour. After cooling to 80 °C for solid-liquid separation, it was acidified with sulfuric acid. After solid-liquid separation of the acidified material, 100.5 g of wet crude dodecanedioic acid was obtained. 100.5 g of this wet crude dodecanedioic acid and 300 g of deionized water were placed in a 500 ml autoclave, adjusted to a pH of 2.5 with sulfuric acid, stirred and heated to 160 °C, maintained at 160 °C for 30 min, then cooled by 1.0 °C every 6 minutes to 80 °C, kept warm for 1.0 hour and then cooled to 60 °C for solid-liquid separation to obtain the crystals. The crystals were washed with 250 g of 60 °C deionized water and dried at 105 °C to obtain the long-chain dicarboxylic acid product. The product quality indicators are shown in Table 1.

[0043] Table 1 shows the quality of the dibasic acid products obtained in the above embodiments and comparative examples. Among them, the total acid refers to the percentage of the dibasic acid content in the total amount of the product. The higher the total acid content, the more dibasic acid contained in the product and the fewer impurities such as protein and pigment. The monobasic acid refers to the proportion of dodecane dibasic acid in the total acid. The more the monobasic acid content, the more dodecane dibasic acid contained in the product and the fewer other dibasic acids (such as tridecane dibasic acid, etc.). The total nitrogen content is related to the content of impurities such as protein. The higher the total nitrogen content, the more the content of impurities such as protein. The light transmittance at 440nm / 550nm refers to the light transmittance of the dimethyl sulfoxide solution of the long-chain dibasic acid at 440 and 550nm. The higher the light transmittance, the fewer impurities in the dibasic acid product.

[0044] From the data shown in Table 1, it can be seen that for the long-chain dibasic acid prepared by the method provided by the present invention, the total acid content and the monobasic acid content have been significantly improved compared with the directly acidified crude product of the membrane filtrate of the dodecane dibasic acid fermentation broth. Correspondingly, the total nitrogen is reduced and the light transmittance is increased, and the relevant test data are also significantly better than those of the comparative example, indicating that the method provided by the present invention can effectively remove a series of impurities such as pigment and protein without damaging the long-chain dibasic acid itself, and can refine the ceramic membrane filtrate of the long-chain dibasic acid fermentation broth without any purification method into a qualified product in one step, and the quality is excellent.

[0045] Table 1

[0046]

[0047] The specific embodiments of the present invention have been described above. Through the above description, relevant staff can make various changes and modifications without departing from the technical idea of the present invention.

Claims

1. A method for refining long-chain dibasic acid in an aqueous phase, characterized in that, It includes the following steps: S10: Place the crude long-chain dibasic acid, an oxidizing agent, and an acid in a reactor, seal the reactor, raise the temperature in the reactor to 100 - 160 °C, and keep the temperature for 0.1 - 3.0 hours; S20: Cool the materials in the reactor to crystallize, perform solid-liquid separation to obtain the crystals, and wash the crystals with deionized water; S30: Dry to obtain the refined long-chain dibasic acid product; In step S10, the oxidizing agent is one or both of ozone and hydrogen peroxide, and the addition amount of the oxidizing agent is 0.1 - 5.0 wt% of the mass of the crude long-chain dibasic acid; the acid is any one or more of sulfuric acid, hydrochloric acid, and phosphoric acid, and the addition amount of the acid is 1 - 10 times the mass of the crude long-chain dibasic acid.

2. The method for refining long-chain dibasic acid in aqueous phase according to claim 1, characterized in that, In step S10, the addition amount of the oxidizing agent is 0.5 - 4.0 wt% of the mass of the crude long-chain dibasic acid, or 0.5 - 3.0 wt%.

3. The method for refining long-chain dibasic acid in aqueous phase according to claim 1, wherein In step S10, the addition amount of the acid is 2 - 8 times the mass of the crude long-chain dibasic acid, or 3 - 6 times.

4. The method for refining long-chain dibasic acid in aqueous phase according to claim 1, characterized in that In step S10, the concentration of the acid is 1 - 4 mol / L, or 1 - 3 mol / L, or 1 - 2 mol / L.

5. The method for refining long-chain dibasic acid in aqueous phase according to claim 1, wherein Step S10 specifically is: Place the crude long-chain dibasic acid, an oxidizing agent, and an acid in a reactor, seal the reactor, turn on the stirring function of the reactor, raise the temperature in the reactor to 100 - 160 °C, and the pressure correspondingly increases to 0.1 - 0.62 Mpa, and keep the temperature for 0.1 - 3.0 hours.

6. The method for refining long-chain dibasic acid in aqueous phase according to claim 1, characterized in that, In step S20, in the materials in the reactor, the content of the long-chain dibasic acid is 10 - 50 wt%.

7. The method for refining long-chain dibasic acid in aqueous phase according to claim 1, wherein In step S10, the crude long-chain dibasic acid placed in the reactor is from any one or more of the following: The crude long-chain dibasic acid obtained by directly acidifying the ceramic membrane clear liquid of the long-chain dibasic acid fermentation broth; The crude long-chain dibasic acid obtained by acidifying the decarbonized clear liquid obtained by decolorizing the ceramic membrane clear liquid of the long-chain dibasic acid fermentation broth with activated carbon; The crude long-chain dibasic acid obtained by acidifying the decarbonized clear liquid obtained by heating and decolorizing the ceramic membrane clear liquid of the long-chain dibasic acid fermentation broth with an oxidizing agent and activated carbon between 100 °C and 160 °C; The crude long-chain dibasic acid containing a small amount of bacteria obtained by directly acidifying the long-chain dibasic acid fermentation broth and then removing most of the bacteria by rinsing or centrifugation.

8. The method for refining long-chain dibasic acid in aqueous phase according to claim 1, wherein In step S10, the crude long-chain dibasic acid is a mixture of one or more of crude decanedioic acid, crude undecanedioic acid, crude dodecanedioic acid, crude tridecanedioic acid, crude tetradecanedioic acid, and crude pentadecanedioic acid.

9. The method for refining long-chain dibasic acid in aqueous phase according to claim 1, characterized in that, In step S20, the step of cooling and crystallizing specifically is: Cool the long-chain dibasic acid materials to 80 - 90 °C, keep the temperature for 0.5 - 2.0 hours, and then cool to 60 °C for solid-liquid separation.

10. The method for refining long-chain dibasic acid in aqueous phase according to claim 1, characterized in that, The crude long-chain dibasic acid added in step S10 is obtained from the ceramic membrane supernatant of the long-chain dibasic acid fermentation broth through a treatment process including acidification. The acid solution used for acidifying the ceramic membrane supernatant is from the filtered supernatant obtained during the preparation of long-chain dibasic acid by the method of aqueous-phase refining of long-chain dibasic acid in the previous batch. The filtered supernatant is obtained by subjecting the material in step S20 to solid-liquid separation to obtain a liquid, then cooling the temperature of the liquid to room temperature to precipitate some solid impurities of heteropolyacid and then filtering.

11. A long-chain dibasic acid, characterized in that, Prepared by the method for aqueous-phase refining of long-chain dibasic acid according to any one of claims 1 to 10.

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