Method for preparing betaine in aqueous phase

Abstract

The invention discloses a method for preparing betaine in a water phase. The method comprises the following steps: adding betaine hydrochloride into a sulfuric acid solution, heating until no gas is generated, cooling and crystallizing to obtain betaine sulfate crystals; dissolving the betaine sulfate crystal in water to obtain a betaine sulfate solution, slowly adding a precipitant for precipitation, and performing centrifugal separation to obtain a precipitate and a betaine aqueous solution; and concentrating the betaine aqueous solution, cooling and crystallizing to obtain betaine monohydrate crystals, and centrifuging and drying to finally obtain the betaine. The method comprises the following steps: preparing betaine hydrochloride into betaine sulfate, adding a precipitator, removing sulfate radicals contained in the betaine sulfate, crystallizing to obtain betaine monohydrate crystals, and centrifuging and drying to finally obtain the high-purity betaine. The method is simple, safe and reliable, few types of impurities are contained in the betaine, and the purity of the obtained betaine is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of betaine purification, in particular to a method for preparing betaine in aqueous phase. BACKGROUND

[0002] Betaine is a kind of vitamin-like nutrient additive which can provide high-efficiency active methyl for animals, and has multiple effects such as promoting fat metabolism of animals, relieving stress, regulating osmotic pressure, promoting growth of poultry, increasing weight and egg production, improving lean meat rate, stabilizing vitamins, preventing coccidiosis, preventing fatty liver, and improving feed utilization rate, and is widely used in the breeding industry.

[0003] There are two known methods for preparing betaine: one is extraction from sugar beet molasses, and the other is chemical synthesis. The most common method for chemical synthesis of betaine is to use chloroacetic acid and trimethylamine to produce betaine in the presence of sodium hydroxide. However, this method produces a large amount of sodium chloride as a by-product, which is generated simultaneously with betaine and doped in betaine, and it is difficult to effectively and completely separate them. Therefore, at present, more betaine hydrochloride is used in feed additives, and it is difficult to use betaine.

[0004] The method for preparing betaine with betaine hydrochloride generally needs to involve solvent extraction method, ion exchange method, electrodialysis desalination method and other treatment methods. The solvent extraction method is the earliest method for purifying betaine. The betaine reaction solution is now reduced pressure concentrated to obtain a viscous betaine-sodium chloride crystallization mother liquor, then an extraction solution is added for extraction, sodium chloride crystals are separated by centrifugation, and are washed with the extraction solution; the extraction solution and the washing solution are combined, concentrated, and then cold-crystallized, centrifuged, and dried under reduced pressure to obtain the betaine product. Chinese patent CN109134287A discloses a method for purifying by-product sodium chloride in the production of betaine or betaine hydrochloride, using isopropyl alcohol, ethanol, or methanol as the extraction solvent, to obtain a betaine product with a purity of more than 98%. Since the water cannot be completely removed during the reduced pressure concentration of the reaction solution, the sodium chloride cannot be completely removed, so the purity of the obtained betaine product is not high. At the same time, a large amount of flammable and explosive solvent is used in the solvent extraction, separation, and solvent recovery processes, which can cause serious safety hazards. The documents “Preparation of low-chlorine betaine” (Ma Xiaoyan et al., Chemical Research and Application, Vol. 22, No. 5) and “New scheme for preparing low-chlorine betaine” (Wu Chao, Invention and Innovation, 2016) also describe a method for preparing low-chlorine betaine by preparing betaine phosphate and using the solubility difference of betaine phosphate in polar high solvents. The polar solvents used for desalination are generally ethanol, methanol, etc., which are flammable, explosive, and toxic, and the recovery of the solvents increases the production cost. The ion exchange method uses anion and cation resins for ion exchange to remove sodium chloride. The disadvantages of this method are complex process, long production cycle, high energy consumption, and a large amount of wastewater generated during the regeneration of ion exchange resins. The electrodialysis desalination method is a commonly used method for desalination and purification, which can remove sodium chloride to the ppm level to obtain high-purity betaine. Chinese patent CN102557970A discloses a method for preparing anhydrous betaine by chemical synthesis; using chloroacetic acid, sodium carbonate, and trimethylamine as main raw materials, through neutralization, substitution, concentration, primary desalination, secondary desalination, evaporation, crystallization, centrifugation, and drying processes, and through the combination of electrodialysis desalination and evaporation desalination and boiling drying machine, anhydrous betaine with a purity of more than 99.9% is produced. CN1511827A discloses a method for separating betaine from an aqueous solution of betaine chemical synthesis reaction products, which is applied to the intermittent circulation of the dilute chamber of the electrodialysis device for the betaine chemical synthesis reaction solution with a relatively constant volume or similar system, and the evaporation desalination method is indispensably applied to the salt water in the concentrated chamber which has been circulated by the concentrated chamber of the electrodialysis device, the liquid volume has been limited, and the salt concentration has been controlled in stages. The disadvantages of the electrodialysis desalination method are large equipment investment, complex process, long production cycle, high energy consumption, and a large amount of wastewater. Therefore, a water-phase synthesis method that does not use organic solvents, is simple, easy to operate, safe, and reliable is needed to prepare betaine. SUMMARY

[0005] In view of the prior art, the present application aims to provide a method for preparing betaine in aqueous phase. In the method, betaine hydrochloride is prepared into betaine sulfate, a precipitant is added to remove sulfate in the betaine sulfate, and monohydrate betaine crystals are obtained after crystallization, followed by centrifugation and drying to obtain high-purity betaine. The method is simple, safe and reliable, and the impurities in the betaine are extremely few, and the purity of the obtained betaine is high.

[0006] To achieve the above object, the present application adopts the following technical solutions: In a first aspect, the present application provides a method for preparing betaine in aqueous phase, which comprises: (1) adding betaine hydrochloride into a sulfuric acid solution, heating until no gas is generated, cooling and crystallizing to obtain betaine sulfate crystals; (2) dissolving the betaine sulfate crystals in water to obtain a betaine sulfate solution, slowly adding a precipitant for precipitation, centrifuging to obtain a precipitate and a betaine aqueous solution, concentrating and cooling the betaine aqueous solution to obtain monohydrate betaine crystals, and finally obtaining betaine through centrifugation and drying.

[0007] Preferably, in step (1), the molar ratio of the betaine hydrochloride to sulfuric acid is 1:1.

[0008] Preferably, in step (1), the heating temperature is 100℃, and the crystallization temperature is 40℃.

[0009] Preferably, in step (2), the precipitant is calcium hydroxide slurry or barium hydroxide solution, and the mass concentration of the calcium hydroxide slurry or barium hydroxide solution is 30%.

[0010] Preferably, the molar ratio of calcium hydroxide to betaine sulfate is 1:1, and the molar ratio of barium hydroxide to betaine sulfate is 1:1.

[0011] Preferably, in step (2), the adding speed of the precipitant is 4-8 g / min.

[0012] Preferably, in step (2), the centrifugation temperature is 30-60℃.

[0013] Preferably, the centrifugation temperature is 60℃.

[0014] In a second aspect, the present application provides the method for use in improving the purity of betaine.

[0015] Preferably, the purity of the betaine is ≥99.1%.

[0016] The present application has the following advantages: (1) The method for preparing betaine in the present application is carried out in water medium, and no organic solvent is used, so that the production process is safer and more environmentally friendly.

[0017] (2) In the present application, betaine hydrochloride is prepared into betaine sulfate, a precipitant is added to remove sulfate contained in the betaine sulfate, and after crystallization, betaine monohydrate crystals are obtained, and then high-purity betaine is finally obtained through centrifugation and drying. The method is simple, safe and reliable, the impurities contained in the betaine are extremely few, and the purity of the obtained betaine is high. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The infrared spectrum of the betaine monohydrate prepared in Example 1. DETAILED DESCRIPTION

[0019] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs.

[0020] In order to enable those skilled in the art to more clearly understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below in combination with specific examples.

[0021] The test materials used in the embodiments of the present application are all conventional test materials in the art, and can be purchased through commercial channels.

[0022] Example 1 (1) Betaine hydrochloride is added into a sulfuric acid solution with equal molar amount of sulfuric acid, heated to 100℃, and after the hydrogen chloride gas is completely released, the temperature is reduced to below 40℃ for crystallization, and betaine sulfate crystals are obtained by filtration, and the filtration mother liquor (still containing part of betaine sulfate and sulfuric acid) is returned to the initial stage of the reaction of betaine hydrochloride and sulfuric acid for recycling. The average yield of betaine sulfate is about 95%.

[0023] (2) 129.1g (0.6mol) of betaine sulfate is dissolved in water, and 148.2g (0.6mol) of 30wt% calcium hydroxide slurry is slowly added within 30min, and after the calcium sulfate precipitate is completely precipitated, the calcium sulfate precipitate is separated by filtration, and the filtration mother liquor is concentrated under reduced pressure, and cooled to below 30℃ for cold crystallization, and betaine monohydrate crystals are obtained by centrifugal filtration, and the filtration mother liquor is returned to the initial stage of the reaction of betaine hydrochloride and sulfuric acid for recycling. From the beginning of the reduced pressure concentration, the operation is repeated in cycles, and finally, the betaine monohydrate is obtained by vacuum drying at 65℃ under a vacuum degree of less than -0.09MPa, and the yield is about 95%. The infrared spectrum of the betaine monohydrate prepared in this embodiment is shown in Figure 1 .

[0024] Example 2 (1) The same as step (1) of Example 1.

[0025] (2) Take betaine sulfate 129.1 g (0.6 mol) and dissolve in water, slowly add 20 wt% barium hydroxide solution 514.0 g (0.6 mol), fully react, and after the barium sulfate precipitate is completely separated, the barium sulfate precipitate is separated by filtration, the filtrate is concentrated under reduced pressure, and the crystal is obtained by cooling and crystallizing, and the crystal is obtained by filtering. From the beginning of the vacuum concentration, the operation is repeated in this cycle, and finally dried at 65°C under vacuum, the vacuum degree is less than -0.09 MPa, and the monohydrate betaine is obtained, the yield is about 96%.

[0026] The betaine prepared in Example 1 and Example 2 is detected according to “Feed Additives Part 2: Vitamins and Betaine” GB 7300.203-2020. The results are shown in Table 1.

[0027] Table 1 Betaine purity As can be seen from Table 1, the purity of the betaine prepared in Example 1 and Example 2 is ≥99.1%, and the types of impurities contained are very few. Therefore, by using the preparation method of the present application, not only the purity of the betaine can be improved, but also the types of impurities can be reduced.

[0028] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing betaine in aqueous phase, characterized in that, The method is as follows: (1) Add betaine hydrochloride to sulfuric acid solution, heat until no gas is produced, cool and crystallize to obtain betaine sulfate crystals; (2) Dissolve betaine sulfate crystals in water to obtain betaine sulfate solution, slowly add precipitant to precipitate, and centrifuge to obtain precipitate and betaine aqueous solution; Betaine aqueous solution was concentrated, cooled and crystallized to obtain betaine monohydrate crystals, which were then centrifuged and dried to finally obtain betaine.

2. The method according to claim 1, characterized in that, In step (1), the molar ratio of betaine hydrochloride to sulfuric acid is 1:

1.

3. The method according to claim 1, characterized in that, In step (1), the heating temperature is 100°C; the crystallization temperature is 40°C.

4. The method according to claim 1, characterized in that, In step (2), the precipitant is calcium hydroxide slurry or barium hydroxide solution; the mass concentration of the calcium hydroxide slurry or barium hydroxide solution is 30%.

5. The method according to claim 4, characterized in that, The molar ratio of calcium hydroxide to betaine sulfate is 1:1; the molar ratio of barium hydroxide to betaine sulfate is 1:

1.

6. The method according to claim 1, characterized in that, In step (2), the precipitant is added at a rate of 4~8 g / min.

7. The method according to claim 1, characterized in that, In step (2), the temperature of centrifugation is 30~60℃.

8. The method according to claim 7, characterized in that, The centrifugal separation temperature is 60℃.

9. The application of the method according to claims 1 to 7 in improving the purity of betaine.

10. The application according to claim 9, characterized in that, The betaine has a purity of ≥99.1%.

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