Method for separating and purifying betaine

Abstract

The invention belongs to the technical field of betaine purification, and particularly relates to a method for separating and purifying betaine, which comprises the following steps: S1, chemically synthesizing a betaine mother solution; s2, primary vacuum concentration; s3, primary crystallization / filtration: adding a poor solvent into the concentrated solution in S2, stirring, filtering, and respectively collecting a filter cake and filtrate; s4, secondary vacuum concentration: performing vacuum concentration on the filtrate in S3; when the solid content of the solution is 30wt%, adding an inhibitor for continuous concentration, and when salt crystallization occurs, stopping heating; s5, secondary crystallization / hot filtration: stirring and crystallizing the concentrated solution obtained in S4 for 2-8 hours, then filtering while hot to remove sodium chloride, cooling and diluting the filtrate, centrifuging to remove the inhibitor, and collecting the centrifugate; and S6, finished product drying: evaporating the centrifugate solvent in the step S5 to dryness and collecting a betaine finished product. The method disclosed by the invention is simple to operate, sodium chloride in betaine is separated at low cost, and the purity and the yield of the purified betaine are high.

Description

Technical Field

[0001] The invention belongs to the technical field of betaine purification, and particularly relates to a method for separating and purifying betaine. Background Art

[0002] Betaine (Bet), also known as glycine betaine and betaine, has a chemical name of trimethylglycine. It was first discovered in Europe in the 19th century. It is a quaternary ammonium water-soluble alkaloid that is widely found in animals, plants and microorganisms. Since the 1970s, research on Bet has gradually become a hot topic and has been widely used in animal husbandry, medicine, agriculture and forestry, food and daily chemicals. Betaine was extracted from the roots, stems, leaves and fruits of natural plants in the early days. With the development of production technology, it can now be chemically synthesized using trimethylamine and chloroacetic acid as raw materials. This product is widely used in medicine, daily chemicals, food additives and feed additives, and is an important basic raw material. Trimethylglycine is a highly efficient and active methyl donor in animals. It plays an important role in nutritional regulation in methyl metabolism and can replace part of methionine and choline. It has the functions of promoting fat metabolism, improving the palatability of feed, alleviating heat stress, regulating the body's osmotic pressure, improving the efficacy of diarrhea drugs, maintaining the stability of vitamin premixes, significantly improving the growth performance of livestock and poultry, reducing carcass fat, increasing lean meat rate and improving carcass quality.

[0003] As the market demand for trimethylglycine increases, extracting trimethylglycine from beet molasses can no longer meet the demand, and people have successfully studied the method of chemically synthesizing trimethylglycine. Using sodium chloroacetate and trimethylamine as raw materials, it is easy to synthesize trimethylglycine in an aqueous solution at normal pressure, but sodium chloride will also be generated at the same time and mixed with the main product, and a small amount of heavy metal substances will also be mixed in the product. These impurities have greatly damaged the quality of the main product betaine.

[0004] Therefore, the difficulty of preparing betaine by chemical synthesis is desalination. The commonly used desalination methods include distillation, membrane separation, and ion exchange resin. CN201110172737 discloses a method for preparing betaine, wherein the mother liquor after the reaction of chloroacetic acid and trimethylamine is passed through an anion exchange resin and then concentrated and crystallized. The disadvantage of this method is that a large amount of waste water is generated, and the raw material consumption is large and the efficiency is low. CN201910158151 discloses a method for preparing betaine by ammonia method, wherein ammonium chloroacetate and trimethylamine are subjected to quaternization reaction, and a betaine product is obtained by evaporation concentration, electrodialysis, re-evaporation concentration, and centrifugal drying. The disadvantage of this method is that the cost is high and the separation and purification operation is complicated. Summary of the invention

[0005] In order to solve the problems in the prior art, the present invention provides a method for separating and purifying betaine, so as to achieve the purpose of simply and low-costly separating sodium chloride from betaine and improving the purity of betaine.

[0006] The present invention solves the technical problem by adopting the following technical solutions:

[0007] The present invention aims to provide a method for separating and purifying betaine, comprising the following steps:

[0008] S1. Chemical synthesis of betaine mother liquor;

[0009] S2. One-time vacuum concentration;

[0010] S3. Primary crystallization / filtration: Add a poor solvent to the S2 concentrate, stir and filter to collect the filter cake and filtrate respectively;

[0011] S4 secondary vacuum concentration: The filtrate in S3 was concentrated under reduced pressure; when the solid content of the solution was 30wt%, the inhibitor was added and the concentration was continued. When salt crystals appeared, the heating was stopped;

[0012] S5. Secondary crystallization / hot filtration: The concentrated solution obtained in S4 is stirred for crystallization for 2 to 8 hours, and then filtered while hot to remove sodium chloride, the filtrate is cooled and diluted, and the inhibitor is removed by centrifugation, and the centrifuge is collected;

[0013] S6. Finished product drying: evaporate the solvent of the centrifuged liquid in S5 and collect the finished betaine product.

[0014] Further, the method for chemically synthesizing betaine mother liquor in S1 is as follows:

[0015] A1: Neutralization: Neutralize chloroacetic acid with sodium hydroxide, control the temperature below 30°C, and adjust the pH to 7.8±0.3.

[0016] A2: Amination: Trimethylamine solution is added dropwise to the neutralized solution of A1. Chloroacetic acid and trimethylamine are weighed in a molar ratio of 1:1.5. After the addition is completed, react at 40-60°C for 2-4 hours to obtain betaine mother liquor.

[0017] Furthermore, the temperature of the first reduced pressure concentration of S2 is 40-60°C and the pressure is -0.06MPa. The concentration end point is that the solid content of the solution is 25wt%. Part of the water, trimethylamine and other volatile organic impurities are first removed.

[0018] Furthermore, the poor solvent added to the first crystallization of S3 is anhydrous ethanol, and the added amount is 15 to 20 times the volume of the first concentrated solution, and the mixture is stirred for 1 hour and then filtered.

[0019] Furthermore, the temperature of the secondary reduced pressure concentration of S4 is 60-80°C and the pressure is -0.06MPa.

[0020] Furthermore, the inhibitor in S4 is glyceryl mono- and distearate, and the added amount thereof is 100 ppm based on the mass of the concentrate.

[0021] Furthermore, in the mono- and distearic glyceryl, the mass percentage content of distearic glyceryl is 40 to 70%.

[0022] Furthermore, the stirring crystallization temperature in S5 is 105°C.

[0023] Compared with the prior art, the beneficial technical effects of the present invention are:

[0024] 1. The separation and purification method of the present invention has low synthesis cost, simple separation and purification steps, and simple operation. The added inhibitor assists betaine crystallization, and can produce a high-purity and high-yield betaine product, and improves the uniformity of the product crystal particles and the fluidity of the product powder.

[0025] 2. The present invention mainly utilizes mono- and distearic glyceryl to provide hydrogen bond donors for betaine. The hydrogen bond donors of mono- and distearic glyceryl are linked to the hydrogen bond acceptors of betaine to form weak hydrogen bonds, thereby increasing the solubility of betaine in the solvent, so as to achieve the purpose of betaine not being precipitated with sodium chloride crystals in the reduced pressure concentration step, thereby separating and purifying betaine, and improving the purity and yield of betaine. The purity can reach more than 98.5%, and the yield can reach more than 98%.

[0026] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above contents of the present invention and its objectives, features and advantages more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the HPLC detection spectrum of betaine prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following embodiments are only exemplary illustrations and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are included in the scope of protection that the present invention is intended to protect.

[0029] In addition, unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0030] Example 1: Chloroacetic acid was added to the reactor, and deionized water was added to stir and dissolve. Sodium hydroxide was added to neutralize under water bath temperature control, and the temperature was controlled not to be higher than 30°C, and the pH was adjusted to 7.8±0.3; trimethylamine solution was added dropwise, and the molar ratio of chloroacetic acid to trimethylamine was 1:1.5. After the addition was completed, the temperature was raised to 40°C and reacted for 4 hours to obtain betaine mother liquor; the mother liquor was transferred to a concentration kettle, and the heater and vacuum pump of the concentration kettle were started to start reduced pressure concentration, and the temperature was raised from room temperature to 60°C, and the pressure was -0.06MPa. The concentration was stopped when the solid content of the solution was 25wt%; the primary concentrate was transferred to a crystallization kettle, and 15 times the concentration was added. The volume of anhydrous ethanol was stirred for 1 hour and then filtered, and the filter cake and filtrate were collected respectively; the filtrate was transferred to a concentration kettle and concentrated and evaporated at 60°C under reduced pressure, and the pressure was -0.06MPa. When the solid content of the solution was 30wt%, 100ppm of mono- and distearic acid glycerol was added to the concentrated solution, and the stirring and concentration were continued until salt crystals appeared. The heating was stopped and the vacuum pump was turned off; the secondary concentrated solution was moved to the crystallization kettle, the crystallization kettle heater and agitator were started, and the crystallization was stirred at 105°C for 8h, and the sodium chloride crystals were filtered while hot, and then the filtrate was cooled to room temperature and diluted with water. After the inhibitor was completely precipitated, the inhibitor was removed by centrifugation and the centrifuge was collected. The centrifuge was evaporated and crystallized, and the collected crystalline solid was dried at 70-80°C. High-purity betaine crystals were obtained with a purity of 99% and a yield of 98%.

[0031] Example 2: Chloroacetic acid was added to the reactor, and deionized water was added to stir and dissolve, and sodium hydroxide was added to neutralize under water bath temperature control. The temperature was controlled not higher than 30°C, and the pH was adjusted to 7.8±0.3. Trimethylamine solution was added dropwise, and the molar ratio of chloroacetic acid to trimethylamine was 1:1.5. After the addition was completed, the temperature was raised to 50°C and reacted for 3 hours to obtain betaine mother liquor. The mother liquor is transferred to the concentration kettle, the heater and vacuum pump of the concentration kettle are started, and the reduced pressure concentration is started. The temperature rises from room temperature to 40°C, the pressure is -0.06MPa, and the concentration is stopped when the solid content of the solution is 25wt%. The primary concentrated solution is transferred to the crystallization kettle, and anhydrous ethanol of 18 times the volume of the concentrated solution is added. After stirring for 1h, the filter cake and the filtrate are collected respectively. The filtrate is transferred to the concentration kettle and concentrated and evaporated at 80°C under reduced pressure. The pressure is -0.06MPa. When the solid content of the solution is 30wt%, 100ppm of mono- and distearic acid glycerol by mass of the concentrated solution is added. Stirring and concentrating are continued until salt crystals appear. Stop heating, turn off the vacuum pump, transfer the secondary concentrated solution to the crystallization kettle, start the heater and agitator of the crystallization kettle, stir and crystallize at 105°C for 5h, filter the sodium chloride crystals while hot, then cool the filtrate to room temperature and dilute with water. After the inhibitor is completely precipitated, centrifuge to remove the inhibitor, and collect the centrifuge. The centrifuge is evaporated and crystallized, and the collected crystalline solid is dried at 70-80°C. High-purity betaine crystals were obtained with a purity of 99.3% and a yield of 98.1%.

[0032] Example 3: Chloroacetic acid was added to the reactor, and deionized water was added to stir and dissolve, and sodium hydroxide was added to neutralize under water bath temperature control. The temperature was controlled not higher than 30°C, and the pH was adjusted to 7.8±0.3. Trimethylamine solution was added dropwise, and the molar ratio of chloroacetic acid to trimethylamine was 1:1.5. After the addition was completed, the temperature was raised to 60°C and reacted for 2 hours to obtain betaine mother liquor. The mother liquor is transferred to the concentration kettle, the heater and vacuum pump of the concentration kettle are started, and the reduced pressure concentration is started. The temperature rises from room temperature to 50°C, the pressure is -0.06MPa, and the concentration is stopped when the solid content of the solution is 25wt%. The primary concentrated solution is transferred to the crystallization kettle, 20 times the volume of the concentrated solution is added with anhydrous ethanol, and the solution is stirred for 1h and filtered. The filter cake and filtrate are collected respectively, and the filtrate is transferred to the concentration kettle and concentrated and evaporated at 70°C under reduced pressure at a pressure of -0.06MPa. When the solid content of the solution is 30wt%, 100ppm of mono- and distearic acid glycerol by mass of the concentrated solution is added, and the stirring and concentration are continued until salt crystals appear. The heating is stopped, the vacuum pump is turned off, the secondary concentrated solution is transferred to the crystallization kettle, the heater and agitator of the crystallization kettle are started, and the crystallization is stirred at 105°C for 2h. The sodium chloride crystals are filtered while hot, and then the filtrate is cooled to room temperature and diluted with water. After the inhibitor is completely precipitated, the inhibitor is removed by centrifugation, and the centrifuge is collected. The centrifuge is evaporated and crystallized, and the collected crystalline solid is dried at 70-80°C. High-purity betaine crystals are obtained with a purity of 98.8% and a yield of 98%.

[0033] Comparative Example 1: Add chloroacetic acid to the reactor, add deionized water and stir to dissolve, and add sodium hydroxide to neutralize under water bath temperature control. Add trimethylamine solution dropwise, and after the addition is complete, heat to 40°C and react for 4h to obtain betaine mother liquor. The mother liquor is moved to a concentration kettle and begins to be concentrated under reduced pressure. The temperature is raised from room temperature to 60°C. When the solid content of the solution is 25wt%, stop concentrating, add 15 times the volume of anhydrous ethanol, stir for 1h and filter, transfer the filtrate to a concentration kettle and concentrate at 60°C under reduced pressure to evaporate. When the solid content of the solution is 30wt%, do not add any inhibitor, continue to stir and concentrate until salt crystals appear, move to a crystallization kettle and stir and crystallize at 105°C for 8h, filter the sodium chloride crystals while hot, then evaporate the filtrate and crystallize, collect the crystalline solid and dry it at 70-80°C. Betaine crystals are obtained with a purity of 95.8% and a yield of 95.7%.

[0034] Comparative Example 2: Chloroacetic acid was added to the reactor, deionized water was added and stirred to dissolve, and sodium hydroxide was added under water bath temperature control to neutralize. Trimethylamine solution was added dropwise, and the temperature was raised to 40°C after the addition was completed, and the reaction was carried out for 4 hours to obtain betaine mother liquor. The mother liquor was moved to a concentration kettle and concentrated under reduced pressure, and the temperature was raised from room temperature to 60°C. When the solid content of the solution was 25wt%, the concentration was stopped, 15 times the volume of anhydrous ethanol was added, and the solution was filtered after stirring for 1 hour. The filtrate was transferred to a concentration kettle and concentrated and evaporated at 60°C under reduced pressure. When the solid content of the solution was 30wt%, 100ppm of sodium chloride solid crystals of the concentrated solution were added, and the concentration was continued to be stirred and concentrated until salt crystals appeared. The mixture was moved to a crystallization kettle and stirred and crystallized at 105°C for 8 hours, and the sodium chloride crystals were filtered while hot, and then the filtrate was evaporated and crystallized, and the crystalline solid was collected and dried at 70-80°C. Betaine crystals were obtained with a purity of 96.8% and a yield of 96.5%.

[0035] Comparative Example 3: Add chloroacetic acid to the reactor, add deionized water and stir to dissolve, and add sodium hydroxide to neutralize under water bath temperature control. Add trimethylamine solution dropwise, and after the addition is complete, heat to 40°C and react for 4 hours to obtain betaine mother liquor. The mother liquor is moved to a concentration kettle and begins to be concentrated under reduced pressure. The temperature rises from room temperature to 60°C. When the solid content of the solution is 25wt%, stop concentrating, add 15 times the volume of anhydrous ethanol, stir for 1h and filter, transfer the filtrate to a concentration kettle and decompress at 60°C to evaporate. When the solid content of the solution is 30wt%, add 100ppm of polyvinyl alcohol by mass of the concentrated liquid, continue to stir and concentrate until salt crystals appear, move to a crystallization kettle and stir and crystallize at 105°C for 8h, filter the sodium chloride crystals while hot, then cool the filtrate to room temperature and dilute with water. After the inhibitor is completely precipitated, centrifuge to remove the inhibitor and collect the centrifuge. The centrifuge is evaporated and crystallized, and the collected crystalline solid is dried at 70-80°C. Betaine crystals are obtained with a purity of 96.4% and a yield of 95.9%.

[0036] Table 1. Comparison of betaine purity and yield between each embodiment and comparative example

[0037]

[0038] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0039] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A method for separating and purifying betaine, characterized in that: The steps include: S1. Chemical synthesis of betaine mother liquor; S2. One-time vacuum concentration; S3. Primary crystallization / filtration: Add a poor solvent to the S2 concentrate, stir and filter to collect the filter cake and filtrate respectively; S4 secondary vacuum concentration: The filtrate in S3 was concentrated under reduced pressure; when the solid content of the solution was 30wt%, the inhibitor was added and the concentration was continued. When salt crystals appeared, the heating was stopped; S5. Secondary crystallization / hot filtration: The concentrated solution obtained in S4 is stirred for crystallization for 2 to 8 hours, and then filtered while hot to remove sodium chloride, the filtrate is cooled and diluted, and the inhibitor is removed by centrifugation, and the centrifuge is collected; S6. Finished product drying: evaporate the solvent of the centrifuged liquid in S5 and collect the finished betaine product.

2. A method for separating and purifying betaine as claimed in claim 1, characterized in that: The method for chemically synthesizing betaine mother liquor in S1 is as follows: A1: Neutralization: Neutralize chloroacetic acid with sodium hydroxide, control the temperature below 30°C, and adjust the pH to 7.8±0.

3. A2: Amination: Trimethylamine solution is added dropwise to the neutralized solution of A1. Chloroacetic acid and trimethylamine are weighed in a molar ratio of 1:1.

5. After the addition is completed, react at 40-60°C for 2-4 hours to obtain betaine mother liquor.

3. A method for separating and purifying betaine as claimed in claim 1, characterized in that: The S2 primary reduced pressure concentration temperature is 40-60°C, the pressure is -0.06MPa, and the concentration end point is that the solid content of the solution is 25wt%.

4. A method for separating and purifying betaine as claimed in claim 1, characterized in that: The poor solvent added to the first crystallization of S3 is anhydrous ethanol, and the added amount is 15 to 20 times the volume of the first concentrated solution. After stirring for 1 hour, filter.

5. A method for separating and purifying betaine as claimed in claim 1, characterized in that: The temperature of S4 secondary vacuum concentration is 60-80°C and the pressure is -0.06MPa.

6. A method for separating and purifying betaine as claimed in claim 1 or 5, characterized in that: The inhibitor in S4 is glyceryl mono- and distearate, and the amount added is 100 ppm based on the mass of the concentrate.

7. A method for separating and purifying betaine as claimed in claim 6, characterized in that: In the mono- and distearic glyceryl, the mass percentage content of distearic glyceryl is 40-70%.

8. A method for separating and purifying betaine as claimed in claim 1, characterized in that: The stirring crystallization temperature in S5 is 105°C.

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