Method for recovering beta-alanine

Abstract

The invention relates to the field of beta-alanine raffinate treatment, and discloses a beta-alanine recovery method, which comprises: (1) carrying out a first reaction after carrying out a first mixing on a beta-alanine-containing raw material and an aminating agent to obtain a first reaction liquid; (2) adding alkali to adjust the pH value of the first reaction solution to be greater than or equal to 13, carrying out ammonia discharge reaction, adjusting the temperature after ammonia discharge is finished, and continuously adding alkali to adjust the pH value to obtain a second reaction solution and ammonia gas; (3) carrying out second mixing on the second reaction liquid and acid, and then carrying out desolventizing treatment; (4) carrying out crystallization treatment on the desolventized product in the step (3), and carrying out solid-liquid separation to obtain beta-alanine; the crystallization treatment in the step (4) comprises alcohol crystallization and water crystallization; in terms of m (NH3), the weight ratio of the aminating agent to the raw material containing beta-alanine is (0.5-2.5): 1. According to the recovery method disclosed by the invention, high beta-alanine purity is maintained, and meanwhile, good yield can be achieved.

Description

Technical Field

[0001] The present invention relates to the field of beta-alanine residual liquid treatment, and in particular to a beta-alanine recovery method. Background Art

[0002] β-Alanine (CAS No. 107-95-9), also known as 3-aminopropionic acid, is the only naturally occurring β-type non-protein amino acid. It is primarily used as a raw material for synthesizing feed additives and medical VB5. It can also be used to produce electroplating corrosion inhibitors, as a biochemical reagent, and as an organic synthesis intermediate. In the prior art, the residual liquid produced during the production of β-alanine through the amination of propylene or acrylic acid (including chemical synthesis and biocatalysis) contains large amounts of 3,3'-iminodipropionic acid (CAS No. 505-47-5) and 3-propionamido-3-alanine (CAS No. 2140-53-6). These residues are typically disposed of through wastewater treatment or incineration, which not only increases environmental remediation costs but also wastes resources. Patent application CN115057790A utilizes a high-temperature, high-pressure amination process to reconstitute β-alanine from 3,3'-iminodipropionic acid. However, β-alanine will be converted into a large amount of 3-propionamido-3-alanine during the amination process, resulting in a low recovery rate of β-alanine. Summary of the Invention

[0003] The present invention aims to overcome the problems of low beta-alanine resource recovery rate, large amount of waste generation, and difficulty in separation and purification in the prior art, and to provide a beta-alanine recovery method that is green and environmentally friendly. In the recovery method, ammonia and products are easily separated, and ammonia can be reused and regenerated. Alcohol is first used to remove organic impurities generated at high temperature, and water crystallization is used to dissolve salts in the crude beta-alanine product, thereby effectively improving the purity and yield of the beta-alanine.

[0004] In order to achieve the above object, the present invention provides a method for recovering β-alanine, which comprises the following steps:

[0005] (1) mixing a raw material containing β-alanine and an aminating agent, and then performing a first reaction to obtain a first reaction solution;

[0006] (2) adding alkali to adjust the pH value of the first reaction liquid to be greater than or equal to 13, performing an ammonia removal reaction, adjusting the temperature after the ammonia removal is completed, and continuing to add alkali to adjust the pH to obtain a second reaction liquid and ammonia gas;

[0007] (3) performing a second mixing of the second reaction solution and the acid, followed by a solvent removal treatment;

[0008] (4) crystallizing the product after desolvation in step (3), and obtaining β-alanine after solid-liquid separation;

[0009] The crystallization treatment in step (4) includes alcohol crystallization and water crystallization;

[0010] Calculated on the basis of m(NH3), the weight ratio of the aminating agent to the raw material containing β-alanine is 0.5-2.5:1.

[0011] Through the above technical solution, the β-alanine recovery method provided by the present invention achieves the following beneficial effects:

[0012] (1) The recovery of β-alanine under strong alkaline conditions can completely convert 3-propionamido-3-alanine into β-alanine, further improving the yield of β-alanine.

[0013] (2) The ammonia generated by the reaction can be recycled and used; the methanol contained in the raw materials containing β-alanine can be recycled for crystallization treatment to reduce waste.

[0014] (3) Crystallization with alcohol can remove impurities generated under high temperature conditions; further, crystallization with water can remove impurity salts generated during the reaction and further increase the yield of β-alanine.

[0015] (4) The method provided by the present invention recovers β-alanine from a β-alanine-containing raw material, while maintaining a high purity of the β-alanine and achieving a good yield. In a preferred embodiment of the present invention, the purity of the obtained β-alanine is ≥99 wt % and the yield is ≥90% by optimizing the amount of the aminating agent, the temperature and time of the first reaction, the pH value, temperature and time adjusted by the base, the amount of the alcohol, the crystallization temperature and time, and the amount of water during recrystallization, the recrystallization temperature and time. DETAILED DESCRIPTION

[0016] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0017] The present invention provides a method for recovering β-alanine, which comprises the following steps:

[0018] (1) mixing a raw material containing β-alanine and an aminating agent, and then performing a first reaction to obtain a first reaction solution;

[0019] (2) adding alkali to adjust the pH value of the first reaction liquid to be greater than or equal to 13, performing an ammonia removal reaction, adjusting the temperature after the ammonia removal is completed, and continuing to add alkali to adjust the pH to obtain a second reaction liquid and ammonia gas;

[0020] (3) performing a second mixing of the second reaction solution and the acid, followed by a solvent removal treatment;

[0021] (4) crystallizing the product after desolvation in step (3), and obtaining β-alanine after solid-liquid separation;

[0022] The crystallization treatment in step (4) includes alcohol crystallization and water crystallization;

[0023] Calculated on the basis of m(NH3), the weight ratio of the aminating agent to the raw material containing β-alanine is 0.5-2.5:1.

[0024] In the present invention, the beta-alanine recovery method is green and environmentally friendly. The recovery method comprises the following steps: mixing a raw material containing beta-alanine with an aminating agent for reaction, and controlling the weight ratio of the aminating agent to the raw material containing beta-alanine, so that ammonia is also generated when beta-alanine is generated, and the ammonia is easily separated from the product. The ammonia is then recovered after alkaline treatment, and the obtained ammonia can be reused and regenerated. Subsequently, alcohol is used to remove organic impurities generated at high temperature, and impure salts generated during the reaction are dissolved with water, thereby further effectively improving the purity and yield of the beta-alanine. Furthermore, a good yield can be achieved while maintaining high purity of the beta-alanine.

[0025] In the present invention, the amount of the aminating agent is calculated as m(NH3).

[0026] According to the present invention, preferably, the weight ratio of the aminating agent to the raw material containing β-alanine, calculated on a basis of m(NH3), is 0.5-2.5:1, for example, it can be 0.5:1, 0.8:1, 0.9:1, 1:1, 1.2:1, 1.5:1, 1.8:1, 2:1, 2.2:1, 2.3:1, 2.4:1 and 2.5:1 or a range formed by any two of the above values.

[0027] In the present invention, when the weight ratio of the aminating agent to the raw material containing β-alanine, calculated as m(NH3), satisfies the above range, it is beneficial to improve the efficiency of converting 3,3'-iminodipropionic acid to β-alanine.

[0028] Furthermore, the weight ratio of the aminating agent to the raw material containing β-alanine is 0.5-2:1, calculated as m(NH3).

[0029] In the present invention, there is no particular limitation on the source of the raw material containing β-alanine, and the raw material can be a crude mother liquor containing β-alanine produced during the preparation of β-alanine.

[0030] In the present invention, after impurities are removed and purified from the raw material containing β-alanine, the structure of the components is confirmed by LC-MS.

[0031] In the present invention, the raw material containing β-alanine contains β-alanine, 3,3'-iminodipropionic acid, 3-propionamido-3-alanine, water, methanol and impurities.

[0032] In the present invention, the contents of β-alanine, 3,3'-iminodipropionic acid and 3-propionamido-3-alanine are determined by high performance liquid chromatography.

[0033] According to the present invention, preferably, based on the total weight of the raw material containing β-alanine, the content of β-alanine is 50-55wt%; the content of 3,3'-iminodipropionic acid is 35-40wt%; and the content of 3-propionamido-3-alanine is 5-15wt%.

[0034] In the present invention, after the raw material containing β-alanine and the aminating agent are mixed and reacted under the first reaction conditions, 3,3'-iminodipropionic acid in the raw material is completely converted into β-alanine, which can effectively remove 3,3'-iminodipropionic acid, and simultaneously generates a byproduct 3-propionamido-3-alanine.

[0035] According to the present invention, preferably, in step (1), the aminating agent is selected from at least one of aqueous ammonia, ammonia gas, liquid ammonia, ammonium bicarbonate and urea.

[0036] In the present invention, the aforementioned aminating agent can provide an alkaline environment, which is beneficial to improving the efficiency of converting 3,3'-iminodipropionic acid to β-alanine, and the generated ammonia can be recycled and reused.

[0037] According to a preferred embodiment of the present invention, the aminating agent is aqueous ammonia.

[0038] In the present invention, there is no particular limitation on the first mixing method, as long as the aminating agent and the β-alanine-containing raw material are uniformly mixed.

[0039] According to the present invention, preferably, the conditions of the first reaction include: temperature of 140-180° C.; time of 2-6 h; and pressure of 1-6 MPa.

[0040] In the present invention, the temperature of the first reaction is 140-180°C, for example, it can be 140°C, 145°C, 150°C, 153°C, 155°C, 158°C, 160°C, 163°C, 165°C, 168°C, 170°C, 175°C and 180°C or a range formed by any two of the above values.

[0041] In the present invention, the time of the first reaction is 2-6h, for example, it can be 2h, 2.3h, 2.5h, 2.8h, 3h, 3.5h, 4h, 4.3h, 4.5h, 4.6h, 4.8h, 5h, 5.3h, 5.5h, 5.8h and 6h or a range formed by any two of the above values.

[0042] In the present invention, the pressure of the first reaction is 1-6 MPa, for example, it can be 1 MPa, 1.3 MPa, 1.5 MPa, 1.8 MPa, 2 MPa, 2.3 MPa, 2.5 MPa, 2.6 MPa, 2.8 MPa, 3 MPa, 3.2 MPa, 3.5 MPa, 3.8 MPa and 4 MPa or a range formed by any two of the above values.

[0043] In the present invention, when the conditions of the first reaction meet the above range, it is beneficial to improve the efficiency of converting 3,3'-iminodipropionic acid to β-alanine.

[0044] Furthermore, in step (1), the conditions of the first reaction include: temperature of 150-160° C.; time of 4-5 h; and pressure of 2-4 MPa.

[0045] In the present invention, the high temperature and high pressure can be carried out in conventional equipment or devices in the art, such as an autoclave.

[0046] According to the present invention, preferably, the base is an alkali metal hydroxide, preferably sodium hydroxide and / or potassium hydroxide.

[0047] In the present invention, the alkali is used in liquid form, for example, it can be liquid alkali.

[0048] In the present invention, the pH value of the second reaction liquid in step (2) is adjusted to be greater than or equal to 13. Under a strongly alkaline environment, the by-product 3-propionamido-3-alanine generated in step (1) can be converted into β-alanine, and the ammonia generated after the ammonia removal reaction can be more completely overflowed.

[0049] Furthermore, alkali is added to adjust the pH value of the second reaction solution to 13-14.

[0050] In the present invention, there is no particular limitation on the amount of the base, as long as the pH of the reaction solution after addition is within the range specified in this application.

[0051] In the present invention, the ammonia removal reaction is preferably carried out by distillation under normal pressure.

[0052] According to the present invention, preferably, the conditions for the ammonia removal reaction include: a temperature of 90-120° C. and a time of 1-5 h.

[0053] In the present invention, when the conditions of the ammonia removal reaction meet the above range, it is beneficial to completely remove ammonia, reduce ammonia residue, and avoid the presence of a large amount of ammonium salt in the subsequent system, which affects the purity and yield of β-alanine.

[0054] Furthermore, the conditions for the ammonia removal reaction include: a temperature of 105-115° C. and a time of 2-4 hours.

[0055] In the present invention, the ammonia removal reaction time refers to the reaction time that continues when the pH reaches the required value of the present invention.

[0056] In the present invention, ammonia gas is generated after the ammonia removal reaction. Preferably, the ammonia gas is absorbed by water and then returned to step (1) to provide at least part of the aminating agent. The ammonia gas generated by the reaction can be recycled to reduce waste.

[0057] According to the present invention, preferably, after the ammonia removal is completed, the temperature is adjusted to 100-150°C, preferably 110-130°C; then, alkali is added to adjust the pH of the second reaction liquid to be greater than or equal to 13, more preferably 13-14; and the reaction is carried out for 2-5 hours, preferably 2-3 hours.

[0058] In the present invention, the reaction time after the completion of ammonia removal refers to the reaction time that is continued when the pH reaches the pH required by the present invention.

[0059] In the present invention, after the ammonia removal is completed, the pH of the reaction solution can be adjusted with a base. The types of the base are as described above and will not be repeated here.

[0060] In the present invention, the temperature and pH of the reaction solution are adjusted after the ammonia removal is completed in order to completely convert 3-propionamido-3-alanine into β-alanine and further improve the purity and yield of β-alanine.

[0061] According to the present invention, preferably, in step (3), the acid is selected from an inorganic acid and / or an organic acid, preferably selected from at least one of sulfuric acid, hydrochloric acid, phosphoric acid, glacial acetic acid, formic acid, acetic acid, propionic acid, n-butyric acid, isobutyric acid and isovaleric acid, more preferably at least one of sulfuric acid, hydrochloric acid and phosphoric acid.

[0062] According to the present invention, preferably, the pH of the solution after the second reaction liquid and the second acid are mixed is 6.8-7.

[0063] In the present invention, there is no particular limitation on the amount of acid used in step (3), as long as the pH of the solution after the second mixing of the second reaction liquid and the acid satisfies the above-mentioned range. The addition of the acid in step (3) can convert the β-alanine salt generated in step (2) into β-alanine, while removing the excess base in step (3).

[0064] In the present invention, in step (3), the desolvation treatment is a conventional operation in the art, for example, it can be vacuum distillation.

[0065] In the present invention, the order of alcohol crystallization and water crystallization in the crystallization treatment of step (4) is not particularly limited. For example, the product after the desolvation treatment can be subjected to water crystallization, and then subjected to alcohol crystallization after solid-liquid separation to obtain the β-alanine; or the product after the desolvation treatment can be subjected to alcohol crystallization, and then subjected to water crystallization after solid-liquid separation to obtain the β-alanine. Further preferably, the crystallization treatment in step (4) is to first perform alcohol crystallization, obtain crude β-alanine after solid-liquid separation, and then perform water crystallization.

[0066] In the present invention, the alcohol used in the alcohol crystallization treatment can be an alcohol with high polarity and good water solubility. The addition of alcohol can remove organic oily matter produced under high temperature conditions and impurities in the raw materials, and is miscible with water in the subsequent recrystallization treatment, thereby further improving the yield of β-alanine.

[0067] According to the present invention, preferably, the alcohol is selected from at least one of methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, ethylene glycol, propylene glycol and glycerol, more preferably methanol.

[0068] According to the present invention, preferably, the weight ratio of the alcohol to the product after the desolventizing treatment is 1.5-5:1, for example, it can be 1.5:1, 1.8:1, 2:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 3:1, 3.5:1, 3.8:1, 4:1, 4.3:1, 4.5:1, 4.8:1 and 5:1 or a range formed by any two of the above values.

[0069] In the present invention, when the weight ratio of the alcohol to the product after the desolvation treatment satisfies the above range, it is beneficial to improve the yield of β-alanine.

[0070] Furthermore, the weight ratio of the alcohol to the product after the desolventizing treatment is 1.5-3:1.

[0071] According to the present invention, preferably, the conditions for the alcohol crystallization treatment include: a temperature of 5-20°C, for example, it can be 5°C, 6°C, 7°C, 8°C, 9°C, 10°C, 11°C, 12°C, 13°C, 14°C, 15°C, 16°C, 17°C, 18°C, 19°C and 20°C or a range formed by any two of the above values; the time is 1-5h, for example, it can be 1h, 1.5h, 1.8h, 2h, 2.3h, 2.5h, 3h, 3.5h, 4h, 4.5h and 5h or a range formed by any two of the above values.

[0072] In the present invention, when the conditions of the alcohol crystallization treatment meet the above range, it is beneficial to improve the yield of β-alanine.

[0073] Furthermore, the conditions for the alcohol crystallization treatment include: temperature of 5-15° C. and time of 1-2.5 h.

[0074] In the present invention, in step (4), the solid-liquid separation is a conventional filtration method in the art.

[0075] In the present invention, the step (4) further comprises completely dissolving and mixing the crude β-alanine and water at 60-95°C, preferably 70-85°C, before the water crystallization treatment.

[0076] According to the present invention, preferably, in step (4), the weight ratio of the crude β-alanine to water is 1:1-5, for example, it can be 1:1, 1:1.3, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:2, 1:2.3, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5 and 1:5 or a range formed by any two of the above values.

[0077] In the present invention, when the weight ratio of water to crude β-alanine satisfies the above range, it is beneficial to dissolve impurity salts in the crude β-alanine and improve the purity and yield of β-alanine.

[0078] Furthermore, the weight ratio of the crude β-alanine to water is 1:1-2.

[0079] According to the present invention, preferably, the conditions for water crystallization include: a temperature of 0-15°C, for example, 0°C, 0.5°C, 1°C, 1.5°C, 2°C, 2.5°C, 3°C, 3.5°C, 4°C, 4.5°C, 5°C, 6°C, 7°C, 8°C, 9°C, 10°C, 11°C, 12°C, 13°C, 14°C and 15°C or a range formed by any two of the above values; and a time of 1-4h.

[0080] In the present invention, when the conditions for water crystallization meet the above range, it is beneficial to improve the purity and yield of β-alanine.

[0081] Furthermore, the conditions for water crystallization include: temperature of 0-10°C and time of 1-2h.

[0082] In the present invention, in step (4), the crude β-alanine is crystallized with water, so that the salts and other impurities generated during the recovery process are dissolved in water, thereby making the β-alanine more pure.

[0083] In the present invention, in step (4), the solid-liquid separation is a conventional filtration method in the art.

[0084] In the present invention, step (4) further comprises drying the product after solid-liquid separation, which can be a conventional drying method in the art, to obtain β-alanine.

[0085] In another embodiment of the present invention, the order of the crystallization treatment is to first perform water crystallization treatment, and then perform alcohol crystallization treatment after solid-liquid separation.

[0086] In the present invention, when water crystallization treatment is performed first, the range of selection of conditions for the water crystallization treatment is relatively wide. Preferably, the weight ratio of the product after the desolventization treatment in step (3) to water is 1:1-5, preferably 1:1-3; the conditions for the water treatment are exactly the same as those described above, and in order to avoid repetition, they will not be repeated here.

[0087] In the present invention, the solid-liquid separation operation after the water treatment is exactly the same as described above and will not be repeated here.

[0088] In the present invention, the type and conditions of the alcohol crystallization are exactly the same as those described above, and will not be described again to avoid repetition.

[0089] In a preferred embodiment of the present invention, the method for recovering β-alanine comprises the following steps:

[0090] (1) mixing the β-alanine-containing raw material and ammonia water, and reacting them at 150-160° C. and 2-4 MPa for 4-5 hours to obtain a first reaction solution;

[0091] (2) adding alkali to adjust the pH value of the first reaction liquid to 13-14, and performing ammonia removal reaction at 105-115° C. After 2-4 hours of ammonia removal, adjusting the temperature to 110-130° C., continuing to add alkali to adjust the pH to 13-14, and continuing the reaction for 2-3 hours to obtain a second reaction liquid and ammonia gas;

[0092] (3) After the second reaction liquid and the acid are mixed for a second time, the mixture is subjected to vacuum distillation, and then methanol is added (the weight ratio of methanol to the product after the vacuum distillation is 1.5-3:1), and crystallization is carried out at 5-15° C. for 1-2.5 hours. After filtering, crude β-alanine is obtained;

[0093] (4) The crude β-alanine and water are mixed in a weight ratio of 1:1-2, recrystallized at 0-10° C. for 1-2 h, and filtered to obtain β-alanine.

[0094] The purity of the finally prepared beta-alanine is greater than or equal to 99wt%, and the yield is greater than or equal to 90%.

[0095] The present invention will be described in detail below by way of examples. In the following examples, all reagents and materials used, unless otherwise specified, can be obtained through commercial channels.

[0096] In the examples and comparative examples, the main components of the raw material containing β-alanine are as follows: 40 wt% of β-alanine, 40 wt% of 3,3'-iminodipropionic acid and 8 wt% of 3-propionamido-3-alanine, and the rest are methanol, water and a small amount of impurities.

[0097] The contents of β-alanine, 3,3'-iminodipropionic acid and 3-propionamido-3-alanine in the β-alanine-containing raw material were determined by high performance liquid chromatography.

[0098] β-Alanine yield (%) = molar amount of β-alanine in the recovered product / (molar amount of β-alanine + molar amount of 3,3'-iminodipropionic acid × 2 + molar amount of 3-propionamido-3-alanine × 2) in the raw material × 100%.

[0099] β-Alanine purity (wt%): determined by high performance liquid chromatography using the external standard method.

[0100] Example 1

[0101] (1) 100 g of a raw material containing β-alanine and 300 g of aqueous ammonia (concentration 25 wt %, m(NH3): raw material containing β-alanine = 0.75:1) were mixed and added to a 1 L autoclave, heated to 160° C. (pressure 2 MPa) and kept warm for 4 h to obtain a first reaction solution;

[0102] (2) adding 30 wt % of liquid caustic soda to adjust the pH of the first reaction solution to 13.5, and distilling the ammonia at 110° C. under normal pressure (the generated ammonia gas is recovered with water). After the ammonia removal is completed for 2 h, the temperature is adjusted to 105° C., and 30% of liquid caustic soda is continued to be added to adjust the pH to 13.5. The reaction is continued for 2 h to obtain a second reaction solution;

[0103] (3) 30% hydrochloric acid was added dropwise to the second reaction solution to adjust the pH to 6.8. The mass of the product after vacuum distillation was 125 g. 200 g of methanol was added, and the temperature was lowered to 15° C. and kept warm for 2 h. The crude β-alanine was obtained after filtration.

[0104] (4) The crude β-alanine and water were mixed in a weight ratio of 1:1.2, heated to 80°C for dissolution, cooled to 7°C, kept warm for 2 hours, filtered, and dried to obtain β-alanine.

[0105] The purity of the product β-alanine was determined to be 99.1 wt % and the yield was 91.1%.

[0106] Example 2

[0107] (1) 100 g of a raw material containing β-alanine and 350 g of aqueous ammonia (concentration 25 wt %, m(NH3): raw material containing β-alanine = 0.875:1) were mixed and added to a 1 L autoclave, heated to 165° C. (pressure 2.4 MPa) and kept warm for 4 h to obtain a first reaction solution;

[0108] (2) 30% liquid caustic soda was added dropwise to adjust the pH of the first reaction solution to 13.5, and ammonia was removed by atmospheric distillation at 110° C. (the generated ammonia gas was recovered with water). After removing ammonia for 3.5 hours, the temperature was adjusted to 105° C., and 30% liquid caustic soda was continued to be added dropwise to adjust the pH to 13.5. The reaction was continued for 2 hours to obtain a second reaction solution;

[0109] (3) 50% sulfuric acid was added dropwise to the second reaction solution to adjust the pH to 6.8. The mass of the product after vacuum distillation was 130 g. 250 g of methanol was added, and the temperature was lowered to 15° C. and kept warm for 2 h. The crude β-alanine was obtained after filtration.

[0110] (4) The crude β-alanine and water were mixed in a weight ratio of 1:1.3, heated to 80°C for dissolution, cooled to 10°C, kept warm for 2 hours, filtered, and dried to obtain β-alanine.

[0111] The purity of the product β-alanine was determined to be 99.2 wt % and the yield was 90.5%.

[0112] Example 3

[0113] (1) 100 g of a raw material containing β-alanine and 250 g of aqueous ammonia (concentration 25 wt %, m(NH3):raw material containing β-alanine = 0.625:1) were mixed and added to a 1 L autoclave. The temperature was raised to 175° C. (pressure 3.1 MPa) and the mixture was kept warm for 3 h to obtain a first reaction solution.

[0114] (2) 40% liquid caustic soda was added dropwise to adjust the pH of the first reaction solution to 14, and ammonia was removed by atmospheric distillation at 105° C. (the generated ammonia gas was recovered with water). After removing ammonia for 4 hours, the temperature was adjusted to 110° C., and 40% liquid caustic soda was continued to be added dropwise to adjust the pH to 14. The reaction was continued for 3 hours to obtain a second reaction solution;

[0115] (3) 80% phosphoric acid was added dropwise to the second reaction solution to adjust the pH to 6.9. The mass of the product after vacuum distillation was 132 g. 300 g of methanol was added, and the temperature was lowered to 10° C. and kept warm for 2 h. The crude β-alanine was obtained after filtration.

[0116] (4) The crude β-alanine and water were mixed in a weight ratio of 1:1.5, heated to 80°C for dissolution, cooled to 8°C, kept warm for 2 hours, filtered, and dried to obtain β-alanine.

[0117] The purity of the product β-alanine was determined to be 99.1 wt % and the yield was 92%.

[0118] Example 4

[0119] (1) 100 g of a raw material containing β-alanine and 250 g of aqueous ammonia (concentration 27 wt %, m(NH3):raw material containing β-alanine = 0.675:1) were mixed and added to a 1 L autoclave. The temperature was raised to 175° C. (pressure 3.6 MPa) and the reaction was carried out for 3 h to obtain a first reaction solution.

[0120] (2) 35% potassium hydroxide solution was added dropwise to adjust the pH of the first reaction solution to 13.6, and ammonia was removed by atmospheric distillation at 105° C. (the generated ammonia gas was recovered with water). After removing ammonia for 3 hours, the temperature was adjusted to 120° C., and 35% potassium hydroxide solution was continued to be added dropwise to adjust the pH to 13.6. The reaction was continued for 2.5 hours to obtain a second reaction solution;

[0121] (3) 30% hydrochloric acid was added dropwise to the second reaction solution to adjust the pH to 6.9. The mass of the product after vacuum distillation was 128 g. 350 g of methanol was added, and the temperature was lowered to 12° C. and kept warm for 4 h. The crude β-alanine was obtained after filtration.

[0122] (4) The crude β-alanine and water were mixed in a weight ratio of 1:1.3, heated to 80°C for dissolution, cooled to 10°C, kept warm for 2.5 hours, filtered, and dried to obtain β-alanine.

[0123] The purity of the product β-alanine was determined to be 99.3 wt % and the yield was 91.8%.

[0124] Example 5

[0125] (1) 100 g of a raw material containing β-alanine and 400 g of aqueous ammonia (concentration 27 wt %, m(NH3): β-alanine-containing raw material = 1.08:1) were mixed and added to a 1 L autoclave, heated to 165° C. (pressure 3.4 MPa) and kept warm for 5 h to obtain a first reaction solution;

[0126] (2) adding 20% potassium hydroxide solution dropwise to adjust the pH of the first reaction solution to 14, and performing atmospheric distillation at 115° C. to remove ammonia (generated ammonia gas is recovered with water). After removing ammonia for 3.5 hours, the temperature was adjusted to 110° C., and 20% potassium hydroxide solution was continuously added dropwise to adjust the pH to 14. The reaction was continued for 3 hours to obtain a second reaction solution.

[0127] (3) 30% hydrochloric acid was added dropwise to the second reaction solution to adjust the pH to 7. The mass of the product after vacuum distillation was 128 g. 250 g of methanol was added, and the temperature was lowered to 7° C. and kept warm for 3 h. The crude β-alanine was obtained after filtration.

[0128] (4) The crude β-alanine and water were mixed in a weight ratio of 1:1.1, heated to 80°C for dissolution, cooled to 10°C, kept warm for 3 hours, filtered, and dried to obtain β-alanine.

[0129] The purity of the product β-alanine was determined to be 99.2 wt % and the yield was 91.3%.

[0130] Example 6

[0131] The method of Example 1 was followed, except that the reaction temperature of the autoclave in step (1) was 110° C., the reaction time was 1 h, and the pressure was 1.7 MPa.

[0132] The purity of the product β-alanine was determined to be 96.5 wt % and the yield was 78.9%.

[0133] Example 7

[0134] The method of Example 1 is followed, except that the temperature is adjusted to 85° C. after the ammonia discharge is completed in step (2).

[0135] The purity of the product β-alanine was determined to be 93.5 wt % and the yield was 70.2%.

[0136] Example 8

[0137] The method of Example 1 is followed, except that in step (4), the crude β-alanine and water are mixed in a weight ratio of 1:3 and then heated to 80° C. to dissolve.

[0138] The purity of the product β-alanine was determined to be 99.3 wt % and the yield was 77.5%.

[0139] Example 9

[0140] The method of Example 1 was followed, except that in step (4), the crude β-alanine and water were mixed in a weight ratio of 1:1.2, the mixture was heated to 80° C. to dissolve, the mixture was cooled to 30° C., the mixture was kept warm for 2 h, and then filtered.

[0141] The purity of the product β-alanine was determined to be 99.5 wt % and the yield was 61.8%.

[0142] Example 10

[0143] The method of Example 1 was followed, except that in step (4), water was added at a weight ratio of 2.2 to the product after vacuum distillation, the temperature was raised to 80°C to dissolve the product, the temperature was lowered to 7°C, the temperature was maintained for 2 hours, and the crude β-alanine was filtered to obtain a crude product. 200 g of methanol was then added to the crude β-alanine, the temperature was lowered to 15°C, the temperature was maintained for 2 hours, and the product was filtered and dried to obtain a crude product of β-alanine.

[0144] The purity of the product β-alanine was determined to be 99.0 wt % and the yield was 80.7%.

[0145] Comparative Example 1

[0146] The method of Example 1 was followed, except that: in step (1), 100 g of a raw material containing β-alanine and 300 g of aqueous ammonia (concentration 10 wt%, m(NH3): raw material containing β-alanine = 0.3:1) were mixed.

[0147] The purity of the product β-alanine was determined to be 87.5 wt % and the yield was 68.9%.

[0148] Comparative Example 2

[0149] The method of Example 1 was followed, except that: in step (3), the pH value of the second reaction solution was adjusted to 12 with 30% liquid alkali, and after the ammonia removal was completed, 30% liquid alkali was continued to be added dropwise to adjust the pH to 12, and the reaction was continued for 2 hours.

[0150] The purity of the product β-alanine was determined to be 94.5 wt % and the yield was 67.7%.

[0151] Comparative Example 3

[0152] The method of Example 1 is followed, except that the crude β-alanine obtained in step (3) is directly dried without performing step (4).

[0153] The purity of the product β-alanine was determined to be 78.4 wt % and the yield was 92.2%.

[0154] As can be seen from the results of the Examples and Comparative Examples, the method provided by the present invention can be used to recover β-alanine from a β-alanine-containing raw material while maintaining a high β-alanine purity and achieving a good yield. Under further preferred conditions, the purity of the obtained β-alanine is ≥99 wt % and the yield is greater than or equal to 90%.

[0155] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for recovering β-alanine, characterized in that: The method comprises the following steps: (1) mixing a raw material containing β-alanine and an aminating agent, and then performing a first reaction to obtain a first reaction solution; (2) adding alkali to adjust the pH value of the first reaction liquid to be greater than or equal to 13, performing an ammonia removal reaction, adjusting the temperature after the ammonia removal is completed, and continuing to add alkali to adjust the pH to obtain a second reaction liquid and ammonia gas; (3) performing a second mixing of the second reaction solution and the acid, followed by a solvent removal treatment; (4) crystallizing the product after desolvation in step (3), and obtaining β-alanine after solid-liquid separation; The crystallization treatment in step (4) includes alcohol crystallization and water crystallization; Calculated on the basis of m(NH3), the weight ratio of the aminating agent to the raw material containing β-alanine is 0.5-2.5:

1.

2. The recycling method according to claim 1, wherein: Based on the total weight of the raw material containing β-alanine, the content of β-alanine is 50-55wt%; the content of 3,3'-iminodipropionic acid is 35-40wt%; and the content of 3-propionamido-3-alanine is 5-15wt%; Preferably, the weight ratio of the aminating agent to the β-alanine-containing raw material is 0.5-2:1, calculated as m(NH3).

3. The recovery method according to claim 1 or 2, wherein: In step (1), the aminating agent is selected from at least one of aqueous ammonia, ammonia gas, liquid ammonia, ammonium bicarbonate and urea, preferably aqueous ammonia.

4. The recovery method according to any one of claims 1 to 3, wherein in step (1), the conditions for the first reaction include: The temperature is 140-180°C, preferably 150-160°C; the time is 2-6h, preferably 4-5h; The pressure is 1-6 MPa, preferably 2-4 MPa.

5. The recovery method according to any one of claims 1 to 4, wherein: In step (2), the base is an alkali metal hydroxide, preferably sodium hydroxide and / or potassium hydroxide; Preferably, alkali is added to adjust the pH value of the second reaction solution to 13-14.

6. The recovery method according to any one of claims 1 to 5, wherein: The conditions for the ammonia removal reaction include: a temperature of 90-120°C, preferably 105-115°C; a time of 1-5 hours, preferably 2-4 hours; Preferably, the ammonia gas is returned to step (1) to provide at least part of the aminating agent.

7. The recovery method according to any one of claims 1 to 6, wherein: In the step (2), after the ammonia removal is completed, the temperature is adjusted to 100-150° C., preferably 110-130° C.; alkali is added to adjust the pH to be greater than or equal to 13, preferably 13-14; and the reaction is carried out for 2-5 hours, preferably 2-3 hours.

8. The recovery method according to any one of claims 1 to 7, wherein: In step (3), the acid is selected from an inorganic acid and / or an organic acid, preferably selected from at least one of sulfuric acid, hydrochloric acid, phosphoric acid, glacial acetic acid, formic acid, acetic acid, propionic acid, n-butyric acid, isobutyric acid and isovaleric acid, more preferably at least one of sulfuric acid, hydrochloric acid and phosphoric acid; Preferably, the pH of the solution after the second reaction liquid and the second acid are mixed is 6.8-7.

9. The recovery method according to any one of claims 1 to 8, wherein: The crystallization treatment in step (4) is to first perform alcohol crystallization, obtain crude β-alanine after solid-liquid separation, and then perform water crystallization; Preferably, in step (4), the alcohol is selected from at least one of methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, ethylene glycol, propylene glycol and glycerol, preferably at least one of methanol, ethanol and isopropanol; Preferably, the weight ratio of the alcohol to the desolvation product is 1.5-5:1, preferably 1.5-3:1; Preferably, the conditions for the alcohol crystallization treatment include: a temperature of 5-20° C., preferably 5-15° C.; and a time of 1-5 h, preferably 1-2.5 h.

10. The recovery method according to any one of claims 1 to 9, wherein: In step (4), the weight ratio of the crude β-alanine to water is 1:1-5, preferably 1:1-2; Preferably, the conditions for water crystallization include: temperature of 0-15°C, preferably 0-10°C; time of 1-4h, preferably 1-2h.