A method for efficiently preparing columnar taurine in a circular manner

Abstract

The present invention discloses a method for preparing a columnar taurine finished product by efficient circulation, which comprises: preparing a taurine aqueous solution of a certain concentration; passing the taurine aqueous solution through an alkaline resin for treatment to remove hydroxyethyl sulfonic acid alkali metal salts and hydroxyethyl sulfonic acid derivatives; monitoring the effluent from the alkaline resin outlet and collecting the effluent that meets the monitoring requirements; and crystallizing the taurine in the collected effluent to obtain taurine crystals. The method of the present invention is innovative in process and has high efficiency. The obtained taurine crystals have the advantages of good quality, good fluidity, no agglomeration, low production cost and high efficiency, and have good prospects for industrial production.

Description

Technical Field

[0001] The invention relates to the technical field of chemical and pharmaceutical crystallization, and in particular to a method for efficiently cyclically preparing columnar taurine. Background Art

[0002] Taurine, chemically known as 2-aminoethanesulfonic acid, is a naturally occurring β-sulfonated amino acid and a sulfur-containing amino acid necessary for the activities of humans and mammals. Although it does not directly participate in the synthesis of proteins and enzymes in the body, it has extremely important physiological functions. It not only participates in maintaining the normal internal environment homeostasis of the body, but also plays an important regulatory role in the normal functioning of the central nervous system, cardiovascular, digestive, urinary, immune, endocrine, reproductive and other systems.

[0003] Taurine has a wide range of applications due to its unique physiological and pharmacological functions: when added to food, it can enhance physical fitness, prevent diseases, eliminate fatigue, and improve work efficiency; when applied to the medical field, it can help treat fatty liver, myocarditis, heart failure, atherosclerosis and other diseases; when added to animal feed, it can promote the growth, development and reproduction of animals. Taurine has a good market prospect.

[0004] At present, the main industrial production methods of taurine in my country are the ethanolamine method and the ethylene oxide method, and crystallization is a key step in separation, purification and product refining. Taurine is a colorless or white small needle-shaped crystal or crystalline powder, odorless, and easily soluble in water. Currently, the taurine products on the market have problems such as small and uneven crystal size, low bulk density, poor fluidity, and easy agglomeration. However, due to the single crystallization method and complicated process, the production enterprises have the disadvantages of low production efficiency, high raw material cost, high energy consumption of public works, and low equipment utilization. The poor quality of taurine crystals and low production efficiency are one of the important reasons affecting product prices, corporate benefits and market applications.

[0005] Patent CN101904819A and Patent CN103830186A both describe a method for preparing taurine granules using a wet mixing granulator. The method has a simple process, strict requirements on the form and specific parameters of the granulator, high dependence on equipment, and serious equipment loss, low utilization rate, and high equipment cost.

[0006] Patent CN101857558A discloses a method for segmented cooling crystallization, which uses industrially pure 2-aminoethanesulfonic acid to refine 2-aminoethanesulfonic acid and avoid the problem of 2-aminoethanesulfonic acid agglomeration. However, this method needs to be carried out under high pressure reaction conditions, and at the same time, it is also necessary to add alkanol to promote activated carbon decolorization and impurity removal, and to coordinate the holding time of the filtrate cooling crystallization to obtain taurine crystals. Not only will alkanol impurities remain in the taurine crystals, but the crystal form of the taurine crystals obtained is cylindrical needle-shaped, which is also different from the columnar crystal form. In addition, the cylindrical needle-shaped taurine crystals also need to be combined with aluminum-plastic film packaging to achieve the purpose of preventing taurine from absorbing moisture and agglomerating.

[0007] Patent CN1872029A describes a method for preparing spherical taurine products by controlling a dryer and drying conditions. The method is primitive, consumes a lot of energy for public works, and increases production costs.

[0008] Patent CN101671283A describes a preparation method of columnar taurine crystals by adding alkaline substances to a taurine aqueous solution to adjust the pH value and then cooling and crystallizing to obtain the columnar taurine crystals. Organic impurities are also introduced, which increases the cost of raw materials and subsequent mother liquor treatment.

[0009] Patent CN103848763A describes a method for obtaining a columnar crystal product by changing the crystal morphology of taurine using an organic carboxylate additive. The raw material cost of this method is low, and the resulting crystal morphology is also good, but the crystallization method is single, resulting in a low yield in the single-pass process. In industrial production, multiple mother liquor applications are required to improve the overall yield of the crystallization operation, and the operation process is cumbersome, which reduces production efficiency.

[0010] Patent CN109694336A describes a rhombus taurine crystal and a preparation method thereof, and obtains a rhombus taurine crystal product. The method has a simple process, but requires the addition of a certain amount of acid, especially an organic acid, so new impurities are introduced. At the same time, the acid will be enriched in industrial production, which increases the difficulty of mother liquor treatment after subsequent extraction of taurine crystals, increases production costs, and is not convenient for large-scale industrial production.

[0011] Patent CN109574886A describes a taurine crystal with improved bulk density and fluidity and no agglomeration and a preparation method thereof, wherein a certain amount of anti-solvent needs to be added to the system at a certain drop rate, introducing a large amount of organic impurities, which will be enriched in industrial production, making it difficult to completely separate the subsequent mother liquor, and the separation also requires a large amount of additional costs.

[0012] Patent CN112479944A describes a taurine and a recrystallization method thereof, wherein a columnar crystal is finally obtained by controlling cooling and heat preservation in sections, wherein the axial length of the crystal is 600 μm to 950 μm, the radial length is 250 μm to 450 μm, and the aspect ratio of the axial direction to the radial direction is 2:1 to 3:1. The particles are relatively small, and microscopic photographs thereof show that the columnar crystal is somewhat different from the standard columnar crystal, and the particle surface is irregular, which will affect the agglomeration performance of the product. Summary of the invention

[0013] The object of the present invention is to provide a method for efficiently cyclically preparing a columnar taurine product, which is used to solve at least one problem of existing taurine products, such as small and uneven crystal size, low bulk density, poor fluidity, and easy agglomeration.

[0014] The present invention discloses a method for preparing a columnar taurine product by efficient circulation, which comprises: preparing a taurine aqueous solution of a certain concentration; passing the taurine aqueous solution through an alkaline resin for treatment to remove hydroxyethyl sulfonic acid alkali metal salt and hydroxyethyl sulfonic acid derivatives; monitoring the effluent from the outlet of the alkaline resin and collecting the effluent that passes the monitoring; and crystallizing the taurine in the collected effluent to obtain taurine crystals.

[0015] According to one embodiment of the method for preparing columnar taurine products in an efficient cycle, the pH value and / or isethionate groups of the outlet effluent of the alkaline resin are monitored, and if the monitoring is unqualified, the unqualified effluent is recycled.

[0016] According to one embodiment of the method for preparing columnar taurine finished product by efficient circulation, the crude taurine is mixed and dissolved with water or taurine mother liquor, and the insoluble solid impurities are removed to obtain the taurine aqueous solution.

[0017] According to an embodiment of the method for preparing columnar taurine finished products by efficient circulation, the preparation process of the taurine aqueous solution includes: subjecting ethylene oxide to an addition reaction with a bisulfite solution to obtain isethionate; mixing the obtained isethionate with ammonia to perform an ammonolysis reaction to obtain an ammonolysis reaction liquid; evaporating the ammonolysis reaction liquid to remove excess ammonia to obtain taurate; converting the obtained taurate into a taurine solution; concentrating and crystallizing the taurine solution to separate a crude taurine product and a taurine mother liquor, preparing the taurine aqueous solution from the crude taurine product, and recycling the taurine mother liquor.

[0018] According to an embodiment of the method for preparing columnar taurine finished products by efficient circulation, the preparation process of the taurine aqueous solution includes: dissolving and crystallizing the crude taurine with water or the recovered taurine essence mother liquor for purification, and then separating to obtain a primary taurine fine product and a primary taurine essence mother liquor; adding the primary taurine fine product to water or the recovered taurine essence mother liquor, decolorizing and filtering, and then cooling and crystallizing; performing solid-liquid separation on the taurine material after cooling and crystallization, and drying the separated taurine wet fine product to obtain a taurine finished product, and recovering the taurine essence mother liquor obtained after the solid-liquid separation, and preparing the taurine aqueous solution through the recovered taurine essence mother liquor.

[0019] According to an embodiment of the method for preparing columnar taurine product with high efficiency and circulation, the alkaline resin column is regenerated with alkali after being saturated.

[0020] According to an embodiment of the method for preparing columnar taurine finished products by efficient circulation, the method further comprises: performing solid-liquid separation on the taurine material after crystallization treatment to obtain taurine mother liquor; wherein the taurine mother liquor is mixed with the crude taurine product and then passed through the alkaline resin as the taurine aqueous solution for treatment for recycling; or the taurine mother liquor is mixed with the effluent before crystallization treatment for recycling.

[0021] According to an embodiment of the method for preparing columnar taurine products with high efficiency and circulation, the effluent is cooled to 5-35°C, preferably 15-25°C, by using a crystallization kettle for cooling and crystallization.

[0022] According to an embodiment of the method for preparing columnar taurine products through efficient circulation, the mass volume concentration of the taurine aqueous solution is 5% to 25%, preferably 10% to 20%.

[0023] According to an embodiment of the method for preparing columnar taurine finished product by efficient circulation, the alkaline resin is a weak alkaline resin, a strong alkaline resin or a combination of the two.

[0024] According to an embodiment of the method for preparing columnar taurine products by efficient circulation, the flow rate of the taurine aqueous solution through the alkaline resin is 0.25-25 BV / h, preferably 5-15 BV / h.

[0025] According to one embodiment of the method for preparing columnar taurine finished product with high efficiency circulation, when the pH value of the effluent at the outlet of the alkaline resin is 5-9, the monitoring is qualified and the effluent is collected; preferably, when the pH value is 6-8, the monitoring is qualified and the effluent is collected.

[0026] According to one embodiment of the method for preparing columnar taurine products by efficient circulation, the alkali used for regenerating the alkaline resin is alkali metal hydroxide, alkali metal carbonate, ammonia water or a combination thereof, wherein sodium hydroxide, ammonia water or a combination thereof is preferred.

[0027] According to an embodiment of the method for preparing columnar taurine product with high efficiency and circulation, the alkali metal isethionate and isethionate derivatives in the effluent obtained by regenerating the alkaline resin are recycled to the aminolysis reaction.

[0028] According to an embodiment of the method for preparing columnar taurine products with high efficiency circulation, the qualified effluent is concentrated to a mass volume ratio of 25% to 40% and then crystallized, with the preferred mass volume ratio being 30% to 35%.

[0029] According to one embodiment of the method for preparing columnar taurine finished product with high efficiency circulation, filtration is performed through an organic nanofiltration membrane, a ceramic nanofiltration membrane, a SIC nanofiltration membrane, a metal microporous filter or a PE microporous filter, wherein filtration through a SIC nanofiltration membrane is preferred.

[0030] According to one embodiment of the method for preparing columnar taurine finished products in an efficient cycle, the crystallization temperature in the crystallization treatment is controlled to be 60-80°C, preferably 65-75°C in the crystallization kettle; the cooling process is as follows: the initial insulation temperature is 65-75°C, the insulation time is 0.5h-1.0h, and the cooling rate is 1°C-20°C / h.

[0031] According to an embodiment of the method for preparing columnar taurine finished product by efficient circulation, the solid-liquid separation is carried out by a plate centrifuge, an overhead centrifuge, a horizontal spiral centrifuge, a filter or a plate and frame.

[0032] According to an embodiment of the method for preparing columnar taurine finished product with high efficiency circulation, the crude taurine aqueous solution is prepared at a temperature range of 0 to 100°C, preferably 35 to 80°C.

[0033] According to an embodiment of the method for preparing columnar taurine products with high efficiency and circulation, the isethionate content is monitored. If the isethionate content is greater than 0.05%, it is unqualified. Preferably, if the isethionate content is greater than 0.005%, it is unqualified. More preferably, if the isethionate content is greater than 0.001%, it is unqualified.

[0034] According to an embodiment of the method for preparing columnar taurine product by high-efficiency circulation, the alkali metal isethionate is alkali metal sodium, alkali metal potassium or alkali metal lithium isethionate.

[0035] The present invention aims at the quality problems of existing commercially available taurine products, such as small crystal size and uneven distribution, low bulk density, poor fluidity, easy agglomeration, etc., as well as the drawbacks of production enterprises due to single crystallization mode and process, low production efficiency, high raw material cost, high energy consumption of public works, low equipment utilization rate, etc., and develops an improved method for preparing columnar taurine crystal products in an efficient cycle. The method is innovative in process, high in efficiency, and through recycling, the production cost and energy consumption are very low. The obtained crystals have the advantages of good quality, good fluidity, no agglomeration, low production cost, and high efficiency, and have good prospects for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A flow chart of an embodiment of a method for cyclically preparing columnar taurine according to the present invention;

[0037] Figure 2 A flow chart of another embodiment of a method for cyclically preparing columnar taurine according to the present invention;

[0038] Figure 3 This is a crystal picture of a method for cyclically preparing columnar taurine according to the present invention;

[0039] Figure 4 Another crystal picture of a method for cyclically preparing columnar taurine according to the present invention;

[0040] Figure 5 This is a crystal picture of taurine produced by existing technology. DETAILED DESCRIPTION

[0041] The following is a further description of the method for cyclically preparing columnar taurine provided by the present invention.

[0042] After long-term and in-depth research, the inventors found that the water content of the crude taurine produced by the existing taurine production process is about 8%, so that the crude product is also mixed with certain trace impurities such as sodium isethionate, isethionate derivatives, taurine derivatives, ethylene glycol, polyether, ethanolamine, sodium sulfate, etc., so that the above-mentioned related impurities are contained in the recrystallization process of taurine. According to the principle of crystallography, the factors affecting the shape of the crystal include changing the supersaturation, changing the solvent system, and impurities; the factors affecting the purity of the crystal include impurities in the mother liquor, crystallization speed, crystal size and particle size distribution; the factors affecting the size of the crystal include temperature, crystal nucleus quality, stirring, etc. Combined with the taurine process, it is analyzed that sodium isethionate and isethionate derivatives contain hydroxyl groups, which are easy to form hydrogen bonds with taurine molecules, thereby affecting the structure of the taurine crystal, and then having a certain impact on the growth process of the taurine crystal after nucleation. At the same time, since the solubility of sodium isethionate and isethionate derivatives is much greater than that of taurine, after taurine is cooled and crystallized, the amount of taurine in the uncrystallized solution is reduced, while sodium isethionate and isethionate derivatives are not affected due to their high solubility, so that the composition of the solution changes continuously during the cooling process, that is, the impurity content gradually increases. The impurities strengthen the hydrogen bonding effect between taurine crystal molecules, resulting in the formation of needle-shaped taurine. Therefore, by separating sodium isethionate and isethionate derivatives before crystallization, not only the impurity content in the crystallization solution is very low, the stability of the crystallization process is ensured, and uniform taurine columnar crystals are achieved, but also the separated isethionate can be used as a raw material for the aminolysis reaction, thus achieving recycling. After a lot of experiments and analysis by the inventors, the trace impurities sodium isethionate and isethionate derivatives contained in the crude taurine product correspond to isethionate, whose acidity is greater than that of taurine. By using this characteristic, we can use appropriate resins to preferentially adsorb and separate the impurities in the crude taurine product. Among them, the basic resin mainly adsorbs anions and also adsorbs trace non-ionic impurities, specifically anions such as isethionate, sulfate, sulfite, chloride, etc. In the present invention, after passing through the basic resin, the impurities such as isethionate, isethionate derivative anions, sulfate, sulfite, etc. are mainly removed. Of course, the adsorbed impurities can be further regenerated by the resin step to elute the adsorbed impurities and collect the effluent of the resin. During the regeneration, the adsorbed anions will come out, such as isethionate, isethionate derivative anions, sulfate, sulfite, etc., and the invalid components such as sulfate can be treated later. The present invention performs crystallization treatment on the separated solution, and the adsorbed resin is regenerated with alkali to obtain isethionate, which is then treated and used as a raw material for ammonolysis reaction, thereby realizing cyclic production.

[0043] Therefore, the method for cyclically preparing columnar taurine provided by the present invention may specifically include:

[0044] Step S1. Ethylene oxide is reacted with a bisulfite solution to obtain isethionate;

[0045] Step S2. mixing the isethionate obtained in S1 with ammonia to obtain an ammonolysis reaction solution under the conditions of a metal salt or a metal base;

[0046] Step S3. After the aminolysis reaction, evaporating to remove excess ammonia to obtain taurine;

[0047] Step S4. converting the obtained taurate into taurine;

[0048] Step S5. Concentrating and crystallizing the taurine solution to separate and obtain a crude taurine product and a taurine mother liquor, wherein the taurine mother liquor can be returned to step S2 after being treated for impurities removal as one of the raw materials of S2;

[0049] S6. Mix the above crude taurine with water to dissolve it, remove the insoluble solid impurities, and then pass it through an alkaline resin column. Collect the taurine solution at the outlet of the alkaline resin column, monitor the outlet pH and the isethionate in the outlet taurine solution. If the isethionate is unqualified, stop collecting. The unqualified material can be returned as a raw material for each step in the taurine production. After the alkaline resin column is saturated, it is regenerated with alkali. The regenerated isethionate can be recycled as a raw material in step S2;

[0050] S7. The taurine solution at the outlet of the alkaline resin column is concentrated, decolorized, filtered and transferred to a crystallization kettle for cooling and crystallization;

[0051] S8. The taurine material after cooling and crystallization is subjected to solid-liquid separation, and the separated taurine wet fine product is then dried to obtain the taurine finished product. The separated taurine fine mother liquor is returned to step S6 to be mixed with the taurine crude product. The returned taurine fine mother liquor can replace the role of water to a certain extent without adding additional water to mix with the taurine crude product. The taurine fine mother liquor can also be returned to step S5 to be mixed with the taurine solution before or after concentrated crystallization for recycling. Preferably, it is returned to step S6.

[0052] For some preferred embodiments,

[0053] In step S1, the bisulfite solution can be a sodium bisulfite solution, the concentration of the sodium bisulfite solution is 9-36wt%, and the molar ratio of sodium bisulfite to ethylene oxide is 1:0.95-1. The temperature of the addition reaction can be 50-80 degrees, and the reaction pressure is greater than 0.1Mpa (expressed in absolute pressure).

[0054] In step S2, the metal salt or metal base is any one of sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, lithium carbonate, or a mixture of any two or more thereof. The temperature of the ammonolysis reaction is 150-280° C., and the reaction pressure is 1-25 MPa.

[0055] In step S3, the evaporation to remove ammonia includes flash evaporation, single-effect evaporation or multiple-effect evaporation, etc., preferably flash evaporation.

[0056] In step S3, the excess ammonia removed by evaporation can be reused in step S2.

[0057] In step S4, taurate can be converted into taurine by acidification, ion exchange, ion membrane or heating, wherein the acid used in the acidification is such as sulfuric acid, hydrochloric acid, phosphoric acid, isethionic acid, sulfurous acid, etc. Preferred are ion exchange resin and ion membrane, and the most preferred is ion exchange resin.

[0058] In step S6, the crude taurine and water need to be mixed and completely dissolved, wherein the temperature of the mixture of the crude taurine and water during the dissolution is 0°C to 100°C, preferably 35°C to 80°C.

[0059] In step S6, the mass volume concentration of the crude taurine aqueous solution is 5 to 25%, preferably 10 to 20%.

[0060] In step S6, the basic resin is a weak basic resin, a strong basic resin, or a combination of the two, and the basic resin used does not adsorb taurine or has a weak adsorption force, because it is more effective to use a basic resin for the treatment of anions in the solution.

[0061] In step S6, the alkaline resin is a weak alkaline resin, a strong alkaline resin, or a combination of the two, and the resin used has a strong adsorption capacity for isethionic acid and its derivatives.

[0062] In step S6, the flow rate of the crude taurine aqueous solution passing through the alkaline resin is controlled to be 0.25-25 BV / h, preferably, the flow rate is controlled to be 5-15 BV / h.

[0063] In step S6, the pH value at the outlet of the alkaline resin column is monitored, and when the pH value is 5-9, the taurine solution at the outlet of the alkaline resin column is collected; further, preferably, when the pH value is 6-8, the taurine solution at the outlet of the alkaline resin column is collected.

[0064] In step S6, the isethionate content is monitored, and the isethionate content in the solution collected by the alkaline resin is less than 0.05%, which is acceptable, preferably less than 0.005%, and more preferably less than 0.001%.

[0065] In step S6, the alkaline solution used for regenerating the alkaline resin is alkali metal hydroxide, alkali metal carbonate or ammonia water, among which sodium hydroxide and ammonia water are preferred.

[0066] In step S6, the isethionate obtained by regenerating the alkaline resin can be directly or concentrated, treated, etc., and then recycled to S2 for aminolysis reaction to further synthesize taurine.

[0067] In step S6, the removed insoluble solid impurities can be returned to various steps for reuse according to the properties of the solid impurities.

[0068] In step S6, when the alkaline resin column is saturated and regenerated with alkali, the adsorbed anions such as isethionate, isethionate derivative anions, sulfate, sulfite, etc. will be released, and the invalid components such as sulfate, sulfite, etc. will be subsequently treated by impurity removal. The specific methods of impurity removal treatment include concentration and impurity removal, cooling and impurity removal, decolorization and impurity removal, ammonia and impurity removal, etc. Of course, the impurities after impurity removal treatment can also be recycled.

[0069] In step S7, the taurine solution is concentrated to a mass volume ratio of 25% to 40%, preferably 30% to 35%.

[0070] In step S7, the adsorbent used for decolorization includes activated carbon, metal or non-metal oxide adsorbent (such as silica gel, alumina, molecular sieve, natural clay, etc.), polymer adsorbent, etc., wherein the mass of the adsorbent is 0.01% to 0.1% of the mass of the crude taurine in step S6, preferably 0.04% to 0.08%.

[0071] In step S7, the filtering methods include: organic nanofiltration membrane, ceramic nanofiltration membrane, SiC nanofiltration membrane, metal microporous filter or PE microporous filter, etc., among which SiC nanofiltration membrane filtration is preferred.

[0072] In step S7, the crystallization temperature of the crystallization liquid in the crystallization kettle is controlled to be 60-80°C, preferably 65-75°C.

[0073] In step S7, during the cooling crystallization process, a heat preservation stage is set at about the crystal precipitation temperature point so that the crystal particles are larger. The crystallization kettle cooling process is as follows: the first heat preservation temperature is 65-75°C, the heat preservation time is 0.2h-1.0h, and the cooling rate is 1°C-20°C / h.

[0074] In step S8, the device used for solid-liquid separation can be a centrifuge, a filter, a plate frame, etc., among which a flat plate centrifuge, an overhead centrifuge, and a horizontal spiral centrifuge are preferred.

[0075] In another embodiment of the method for preparing columnar taurine in an efficient cycle according to the present invention, the crude taurine may be purified to obtain a refined product, and after reducing the content of sodium isethionate and isethionate derivatives, the refined product may be treated with an alkaline resin for recycling, thereby realizing the cyclic preparation of columnar taurine. Specifically, the method may include:

[0076] S1. Ethylene oxide reacts with a bisulfite solution to obtain isethionate;

[0077] S2. The isethionate obtained in S1 and ammonia are mixed with the ammonolysis reaction solution under the conditions of a metal salt or a metal base;

[0078] S3. After the aminolysis reaction, the excess ammonia is removed by evaporation to obtain taurine;

[0079] S4. converting the obtained taurate into taurine;

[0080] S5. The taurine solution is concentrated and crystallized to separate the crude taurine and the taurine mother liquor, wherein the taurine mother liquor can be returned to step S2 after treatment;

[0081] S6. The crude taurine in S5 is dissolved and crystallized with water or taurine concentrate to purify, and a taurine concentrate and a taurine concentrate are obtained after separation. The separated taurine concentrate is returned to S5 for treatment or reused to S6 to be mixed with the crude taurine again;

[0082] S7. After adding a taurine product, water or taurine concentrate solution (which may be concentrate after treatment in step S9), activated carbon, stirring and then heating to decolorize and filter, the filtered solution is input to a crystallization kettle for cooling and crystallization;

[0083] S8. The taurine material after cooling and crystallization is subjected to solid-liquid separation, and the separated taurine wet fine product is then dried to obtain a taurine finished product;

[0084] S9. The taurine mother liquor separated in step S8 is passed through an alkaline resin column again, and the taurine solution at the outlet of the alkaline resin column is collected, and the outlet pH and the isethionate in the outlet taurine solution are monitored. After the alkaline resin column is saturated, it is regenerated with alkali, and the isethionate obtained by regeneration can be used as a raw material for step S2 for recycling; the collected taurine solution, i.e., the taurine mother liquor, is returned to S7 for recycling, and the taurine mother liquor can also be returned to step S6 to mix with the taurine crude product. The taurine mother liquor can replace the role of water to a certain extent, thereby reducing the additional water addition.

[0085] The following further describes the effects of the method for preparing columnar taurine by circulation through a plurality of specific examples. The following examples show the practice of the present invention. The raw materials used are commercially available products unless otherwise specified. The methods used are conventional methods unless otherwise specified. The material content refers to the mass volume percentage unless otherwise specified. The content of the substance in the detection reaction can be displayed by HPLC and LC-MS analysis methods.

[0086] In one embodiment, the process for preparing crude taurine comprises:

[0087] (1) Preparation of Sodium Isethionate A certain amount of sodium bisulfite solution is reacted with ethylene oxide at a molar ratio of sodium bisulfite to ethylene oxide of 1:0.95-1:1 under the conditions of a pressure of 0.1 MPa, a pH value of 5.0-9.0, and a temperature of 60-80° C. to prepare sodium isethionate.

[0088] (2) Preparation of sodium taurine: Sodium hydroxyethyl sulfonate and ammonia are subjected to ammonolysis reaction under the condition of adding sodium hydroxide. The ammonolysis reaction is carried out at a temperature of 250-270°C and a pressure of 10-15 MPa for 45 minutes. After the reaction is completed, the ammonia is flashed off to obtain a sodium taurine solution.

[0089] (3) Conversion of sodium taurate to taurine: The sodium taurate solution of step (2) is taken and passed through an acidic resin column at a certain flow rate. The outlet liquid of the resin column is collected as the taurine solution. When the outlet liquid index is substantially consistent with the inlet liquid index, the feeding and discharging are stopped. For example, the outlet liquid pH value is close to the inlet liquid pH value. The liquid in the resin column is then washed and recovered with deionized water. After the material is washed, an acid is passed through the resin at a certain flow rate for regeneration. After the regeneration is completed, the resin is washed with pure water and then the resin can be fed for the next time.

[0090] (4) Preparation of crude taurine: About 1850 mL of the collected taurine solution was taken, and the material with a taurine content of 6.7% was detected, concentrated, cooled to 20° C. for crystallization, and then centrifuged to obtain 125 g of crude taurine with a mass percentage of 92.5% and a moisture content of 7%. The remaining taurine mother liquor was 72 mL, and the mass volume percentage of the taurine mother liquor was 11.56%.

[0091] Based on the above-mentioned process of preparing crude taurine, a method for extracting taurine existing in the art is adopted, which includes the following steps:

[0092] Take the prepared taurine crude product, add 1160g water to 500g taurine crude product (mass content 92.5%, moisture 7%), add 0.5g activated carbon, stir and heat to 90℃, keep warm for 15min, and filter while hot. Pour the filtrate into a crystallization bottle, keep warm at 65-75℃ for 30min, then control the cooling rate to 10℃ / h, cool to 20℃, separate, and dry to obtain 324g of taurine dry fine product and 1380mL of taurine fine mother liquor (taurine content 9.86%). The hydroxyethyl sulfonate content in the filtrate before cooling and crystallization was detected to be 0.28%. The obtained taurine is slender needle-shaped crystals with a particle size of 0.1 to 1mm, and the bulk density of the obtained taurine is 0.7g / mL. The particle size screening situation is shown in Table 1:

[0093] Table 1

[0094]

[0095] Compared with the above-mentioned prior art, the method for extracting taurine of the present invention comprises:

[0096] Take the prepared taurine crude product, add 2500g water to 500g taurine crude product (mass content 92.5%, water content 7%), stir and heat until dissolved, and remove insoluble impurities by coarse filtration. Then pass the solution through a 125ml alkaline resin column at a speed of 10BV / h under heat preservation conditions, collect the solution at the outlet of the resin column, and when the pH is detected to be 7.5, concentrate the resulting solution to more than 30% (mass volume ratio), add 0.1g activated carbon thereto, keep warm for 15min, and filter while hot. Pour the filtrate into a crystallization bottle, keep warm at 65-75℃ for 30min, then control the cooling rate to 10℃ / h, cool to 20℃, separate, and dry to obtain 353g of taurine dry fine product and 1125mL of taurine refined mother (content 9.68%). The content of isethionate in the taurine filtrate before cooling and crystallization is 0.02%. The obtained taurine is a columnar crystal with a particle size of 2 to 4 mm in length, 0.4 to 0.6 mm in width, and 0.2 to 0.4 mm in thickness; the bulk density of the obtained taurine is 0.87 g / mL. The particle size screening results are shown in Table 2:

[0097] Table 2

[0098]

[0099] Further, in a specific embodiment, the process of recycling the material (i.e., the regenerated liquid) after preparing the columnar crystals includes:

[0100] (1) Collection of regeneration solution: The alkaline resin after adsorption saturation was regenerated with 600 g of 5% by mass sodium hydroxide solution and the regenerated solution was collected.

[0101] (2) Returning to prepare sodium taurine: the regeneration liquid is mixed with the sodium isethionate solution, wherein the molar ratio of the regeneration liquid in the mixed liquid can be 0.1%-100%, and sodium hydroxide and ammonia are added to carry out an ammonolysis reaction, and the ammonolysis reaction is carried out at a temperature of 250-270°C and a pressure of 10-15MPa for 45 minutes. After the reaction is completed, the ammonia is flashed off to drive off the ammonia gas, and the resulting solution is a sodium taurine solution. If the regeneration liquid is obtained by regeneration with sodium hydroxide, and the sodium hydroxide in the mixed liquid after adding the regeneration liquid has reached more than 0.1% of the molar amount of sodium isethionate in the mixed liquid, sodium hydroxide does not need to be added before ammonolysis; if the regeneration liquid is obtained by regeneration with ammonia, sodium hydroxide needs to be added again.

[0102] (3) Conversion of sodium taurate to taurine: Take the sodium taurate solution and pass it through an acidic resin column at a certain flow rate. Collect the outlet liquid of the resin column as the taurine solution. When the outlet liquid index is basically consistent with the inlet liquid index (such as the pH value is close), stop feeding. Then use deionized water to wash and recover the liquid in the resin column. After the material is washed, use acid to pass through the resin at a certain flow rate for regeneration. After regeneration, wash the resin with pure water again, and then the resin can be fed next time.

[0103] (4) Preparation of crude taurine: About 8000 mL of the collected taurine solution was taken, and the taurine content was detected to be 6.8%. The material was concentrated, cooled to 20° C. for crystallization, and then centrifuged to obtain 550 g of a crude product with a taurine content of 92.6% and a water content of 6.9%. 300 mL of mother liquor remained, and the mass volume percentage of taurine mother liquor was 11.45%.

[0104] (5) Taurine crystallization: Take 500g of the obtained crude taurine (92.6% by mass, 6.9% by water), add 2500g of water, stir and heat until dissolved, and filter to remove insoluble impurities. Then pass the solution through a 125ml alkaline resin column at a speed of 10BV / h under heat preservation conditions, collect the solution at the outlet of the resin column, and detect its pH value to be 7.5. Then concentrate the obtained outlet solution to more than 30% (mass volume ratio), add 0.1g of activated carbon, keep warm for 15min, and filter while hot. Pour the filtrate into a crystallization bottle, keep warm at 65-75℃ for 30min, and then control the cooling rate of 10℃ / h to cool to 20℃, and then separate and dry to obtain 354g of dry fine product and 1115mL of refined mother (content 9.65%). The content of isethionate in the filtrate before cooling and crystallization is 0.01%. The obtained taurine is a columnar crystal with a particle size of 2 to 4 mm in length, 0.4 to 0.6 mm in width, and 0.2 to 0.4 mm in thickness. The bulk density of the obtained taurine is 0.85 g / mL. The particle size screening results are shown in Table 3:

[0105] Table 3

[0106]

[0107] Furthermore, taurine crystallization was performed when the crude taurine was applied to the sperm mother to verify whether the taurine crystallization effect was deteriorated after the application of the sperm mother.

[0108] The specific taurine crystallization process includes:

[0109] Take 500g of the prepared taurine crude product (92.6% by mass, 6.9% by water), add 1100ml of refined mother obtained in the taurine crystallization process, add 1900g of pure water, stir and heat until dissolved, and remove insoluble impurities by coarse filtration. Then pass the solution through a 125ml alkaline resin column at a speed of 10BV / h under heat preservation conditions, collect the solution at the outlet of the resin column, detect that the pH value is 7.5, and then concentrate the resulting solution to more than 30% (mass volume ratio), add 0.1g of activated carbon thereto, keep warm for 15min, and filter while hot. Pour the filtrate into a crystallization bottle, keep warm at 65-75℃ for 30min, subsequently control the cooling rate to 10℃ / h, cool to 20℃, separate, and dry to obtain 440g of dry fine product and 1350mL of refined mother (content 9.70%). The hydroxyethyl sulfonate content in the filtrate before cooling crystallization is detected to be 0.01%. The obtained taurine is a columnar crystal with a particle size of 2 to 4 mm in length, 0.4 to 0.6 mm in width, and 0.2 to 0.4 mm in thickness; the bulk density of the obtained taurine is 0.86 g / mL. The particle size screening conditions are shown in Table 4:

[0110] Table 4

[0111]

[0112] Further, through the control experiment group, it was verified that in the process of taurine crystallization, after impurities were removed by resin, the effect of artificially adding sodium hydroxyethyl sulfonate on the crystallization of taurine was affected, and it was found that sodium hydroxyethyl sulfonate had a greater effect on the crystallization.

[0113] The specific taurine crystallization process includes:

[0114] Take 500g of crude taurine (92.5% by mass, 7% by water), add 2500g of water, stir and heat until dissolved, and remove insoluble impurities by coarse filtration. Then pass the solution through a 125ml alkaline resin column at a speed of 10BV / h under heat preservation conditions, collect the solution at the outlet of the resin column, detect the pH value to be 7.5, and then concentrate the obtained outlet solution to more than 30% (mass volume ratio), add 0.1g of activated carbon and 0.5g of sodium hydroxyethyl sulfonate, keep warm for 15min, and filter while hot. Pour the filtrate into a crystallization bottle, keep warm at 65-75℃ for 30min, then control the cooling rate to 10℃ / h, cool to 20℃, separate, and dry to obtain 335g of dry fine product and 1300mL of refined mother (content 9.75%). The hydroxyethyl sulfonate content in the filtrate before cooling and crystallization is 0.05%. The obtained taurine is in the form of elongated needle-shaped crystals with a particle size of 0.1 to 1 mm. The bulk density of the obtained taurine is 0.71 g / mL. The particle size screening results are shown in Table 5:

[0115] Table 5

[0116]

[0117] Based on the above embodiments, the taurine crystals obtained by the present invention are columnar crystals with large particles and uniform particle size distribution. Specifically, the particle size is 2 to 4 mm long, 0.4-0.6 mm wide, and 0.2 to 0.4 mm thick; the particle size screening is as follows: the proportion of particles below 40 mesh is greater than 35%, the proportion of particles below 80 mesh is greater than 90%, and the proportion of fine powder above 120 mesh is less than 3%. The bulk density of the obtained taurine is high, reaching 0.8 g / mL to 0.9 g / mL. The overall fluidity is good, the filtering and drying speeds are fast, and the packaging, storage, transportation, and use performances are excellent, which is more convenient to use. In addition, the method for preparing columnar taurine in a cycle according to the present invention does not add any auxiliary substances during the crystallization process, so that there will be no residue of any auxiliary substances in the taurine product. In addition, the purity of the taurine product is further guaranteed after the crystallization liquid is purified, and the mass content is greater than 99.8%. At the same time, the present invention realizes recycling, greatly reduces the production cost, and is very convenient for industrial implementation. It should be further explained that the taurine crystallization method of the present invention can be operated both intermittently and continuously, and the crystallization process is carried out under normal pressure, the conditions are easy to control, and it is more conducive to large-scale industrial production.

[0118] In summary, the present invention provides a method for preparing taurine columnar crystals based on the inventor's long-term experimental summary, which can make the taurine crystals have uniform particle size distribution, high bulk density, good fluidity, no agglomeration, fast filtering and drying speed, and excellent packaging, storage and transportation, and use performance. At the same time, the recycling of taurine mother liquor is realized. The problems of slender crystal form, small crystal form, and easy agglomeration of existing taurine products are cleverly solved, and no new organic reagents are introduced. The product purity is very high, the operation is simple and it is very convenient for industrial implementation.

[0119] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a columnar taurine product by efficient circulation, characterized in that: include: The ethylene oxide is subjected to an addition reaction with a bisulfite solution to obtain isethionate; The obtained isethionate and ammonia are mixed to carry out an ammonolysis reaction to obtain an ammonolysis reaction liquid; The ammonolysis reaction solution is evaporated to remove excess ammonia to obtain taurine; converting the obtained taurine salt into a taurine solution, concentrating and crystallizing the taurine solution, separating and obtaining a crude taurine product and a taurine mother liquor, and preparing the crude taurine product aqueous solution from the crude taurine product; Passing the crude taurine aqueous solution through a basic resin for treatment to remove alkali metal isethionate and isethionate derivatives; Monitor the isethionate content of the effluent at the outlet of the alkaline resin, collect the effluent that passes the monitoring, and if the isethionate content is greater than 0.05%, it is unqualified; The taurine in the collected effluent is subjected to crystallization treatment to obtain columnar taurine crystals.

2. The method for preparing a columnar taurine product by high-efficiency circulation according to claim 1, characterized in that: The pH value and / or isethionate group of the outlet effluent of the alkaline resin are monitored. If the monitoring result is unqualified, the effluent with unqualified monitoring result is recycled.

3. The method for preparing a columnar taurine product by high-efficiency circulation according to claim 1, characterized in that: The crude taurine is mixed and dissolved with water or taurine mother liquor, and then the insoluble solid impurities are removed to obtain the crude taurine aqueous solution.

4. The method for preparing a columnar taurine product by high-efficiency circulation according to claim 1, characterized in that: The taurine mother liquor is recycled.

5. The method for preparing a columnar taurine product by high-efficiency circulation as claimed in claim 1, characterized in that: Also includes: The crude taurine is dissolved and crystallized with water or recovered taurine essence mother liquor for purification, and then separated to obtain primary taurine fine product and primary taurine essence mother liquor; After adding the first taurine fine product to water or the recovered taurine fine mother liquor, decolorization and filtration are performed, and then cooling and crystallization treatment is performed; The taurine material after cooling and crystallization is subjected to solid-liquid separation, and the separated taurine wet fine product is then dried to obtain the taurine finished product. The taurine concentrate mother liquor obtained after the solid-liquid separation is recovered, and the taurine crude product aqueous solution is prepared by the recovered taurine concentrate mother liquor.

6. The method for preparing columnar taurine product by efficient circulation according to claim 1, characterized in that: After the basic resin column is saturated, it is regenerated with alkali.

7. The method for preparing columnar taurine product by efficient circulation according to claim 1, characterized in that: Further including: Performing solid-liquid separation on the taurine material after the crystallization treatment to obtain taurine concentrate mother liquor; wherein the taurine concentrate mother solution is mixed with the taurine crude product and then passed through the alkaline resin as the taurine crude product aqueous solution for recycling; or The taurine essence mother liquor is mixed with the effluent before the crystallization treatment for recycling.

8. The method for preparing columnar taurine product by high-efficiency circulation as claimed in claim 1, characterized in that: The crystallization kettle is used for cooling and crystallization treatment, and the temperature of the effluent is reduced to 5-35°C.

9. The method for preparing a columnar taurine product by high-efficiency circulation as claimed in claim 1, characterized in that: The crystallization kettle is used for cooling and crystallization treatment, and the temperature of the effluent is reduced to 15-25°C.

10. The method for preparing columnar taurine product by high-efficiency circulation according to claim 1, characterized in that: The mass volume concentration of the crude taurine aqueous solution is 5% to 25%.

11. The method for preparing columnar taurine product by high-efficiency circulation according to claim 1, characterized in that: The mass volume concentration of the crude taurine aqueous solution is 10% to 20%.

12. The method for preparing columnar taurine product by high-efficiency circulation according to claim 1, characterized in that: The alkaline resin is a weak alkaline resin, a strong alkaline resin or a combination of the two.

13. The method for preparing columnar taurine product by high-efficiency circulation according to claim 1, characterized in that: The flow rate of the crude taurine aqueous solution through the basic resin is 0.25-25 BV / h.

14. The method for preparing columnar taurine product by high-efficiency circulation according to claim 1, characterized in that: The flow rate of the crude taurine aqueous solution through the basic resin is 5-15 BV / h.

15. The method for preparing columnar taurine product by high-efficiency circulation according to claim 1 or 2, characterized in that: When the pH value of the effluent from the outlet of the alkaline resin is 5-9, the monitoring is qualified, and the effluent is collected.

16. The method for preparing columnar taurine product by high-efficiency circulation according to claim 1 or 2, characterized in that: When the pH value of the effluent from the outlet of the alkaline resin is 6-8, the monitoring is qualified and the effluent is collected.

17. The method for preparing columnar taurine product by high-efficiency circulation as claimed in claim 4, characterized in that: The alkali used for regenerating the alkaline resin is alkali metal hydroxide, alkali metal carbonate, ammonia water or a combination thereof.

18. The method for preparing columnar taurine product by high-efficiency circulation as claimed in claim 4, characterized in that: The alkali used for regenerating the alkaline resin is sodium hydroxide, ammonia water or a combination of the two.

19. The method for preparing columnar taurine product by high-efficiency circulation as claimed in claim 4, characterized in that: The alkali metal isethionate and isethionate derivatives in the effluent obtained by regenerating the basic resin are recycled to the aminolysis reaction.

20. The method for preparing columnar taurine product by high efficiency circulation as claimed in claim 1, characterized in that: The qualified effluent is concentrated to a mass volume ratio of 25% to 40% and then crystallized.

21. The method for preparing columnar taurine product by high-efficiency circulation as claimed in claim 1, characterized in that: The qualified effluent is concentrated to a mass volume ratio of 30% to 35% and then crystallized.

22. The method for preparing columnar taurine product by high-efficiency circulation as claimed in claim 5, characterized in that: Filter through organic nanofiltration membrane, ceramic nanofiltration membrane, sic nanofiltration membrane, metal microporous filter or PE microporous filter.

23. The method for preparing columnar taurine product by high-efficiency circulation as claimed in claim 5, characterized in that: Filter through a sic nanofiltration membrane.

24. The method for preparing columnar taurine product by high-efficiency circulation as claimed in claim 5, characterized in that: The crystallization temperature in the crystallization process is controlled to be 60-80°C in the crystallization kettle; The cooling process is as follows: the initial insulation temperature is 65-75°C, the insulation time is 0.5h-1.0h, and the cooling rate is 1°C-20°C / h.

25. The method for preparing columnar taurine product by high-efficiency circulation as claimed in claim 5, characterized in that: The crystallization temperature in the crystallization process is controlled to be 65-75°C in the crystallization kettle; The cooling process is as follows: the initial insulation temperature is 65-75°C, the insulation time is 0.5h-1.0h, and the cooling rate is 1°C-20°C / h.

26. The method for preparing columnar taurine product by high-efficiency circulation as claimed in claim 5, characterized in that: The solid-liquid separation is carried out by a plate centrifuge, an overhead centrifuge, a horizontal spiral centrifuge, a filter or a plate and frame.

27. The method for preparing columnar taurine product by high efficiency circulation as claimed in claim 2, characterized in that: The crude taurine aqueous solution is prepared at a temperature ranging from 0 to 100°C.

28. The method for preparing a columnar taurine product by high-efficiency circulation as claimed in claim 2, characterized in that: The crude taurine aqueous solution is prepared at a temperature ranging from 35 to 80°C.

29. The method for preparing a columnar taurine product by high-efficiency circulation as claimed in claim 2, characterized in that: Monitor the isethionate group. If the isethionate group content is greater than 0.005%, it is unqualified.

30. The method for preparing a columnar taurine product by high-efficiency circulation as claimed in claim 2, characterized in that: Monitor the isethionate group. If the isethionate group content is greater than 0.001%, it is unqualified.

31. The method for preparing a columnar taurine product by high-efficiency circulation as claimed in claim 1, characterized in that: The alkali metal isethionate is alkali metal sodium, alkali metal potassium or alkali metal lithium isethionate.

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