Method for preparing taurine

Abstract

The present invention discloses a method for preparing taurine. According to the method, ethylene oxide reacts with hydrogen sulfite to generate isethionate, after the isethionate and ammonia are subjected to an ammonolysis reaction under a microwave condition, ammonia removal is conducted to obtain a taurine salt solution, the taurine salt solution is converted into a taurine solution through acidification or ion exchange or ion membrane or heating, and taurine is extracted through concentration and crystallization. According to the present invention, the reaction time can be shortened, and the reaction temperature and pressure can be reduced, thereby achieving high yield and reducing energy consumption.

Claims

1. A method for preparing taurine, comprising: in a production process of taurine by an ethylene oxide method, subjecting isethionate and ammonia to an ammonolysis reaction under a microwave condition, obtaining a taurate and converting the taurate to a finished taurine product.

2. The method for preparing the taurine according to claim 1, wherein the ammonolysis reaction conducted under the microwave condition is conducted for 0.4-60 min, at 50-260° C., under the pressure of 0.1-22 MPa.

3. The method for preparing the taurine according to claim 1, wherein the ammonolysis reaction conducted under the microwave condition is conducted for 0.5-35 min, at 80-200° C., under the pressure of 1-10 MPa.

4. The method for preparing the taurine according to claim 1, wherein the ammonolysis reaction conducted under the microwave condition is conducted for 1-10 min, at 100-150° C., under the pressure of 3-6 MPa.

5. The method for preparing the taurine according to claim 1, wherein the ammonolysis reaction conducted under the microwave condition is conducted for 0.5 min, at 150-230° C., under the pressure of 6-15 MPa.

6. The method for preparing the taurine according to claim 1, wherein the ammonolysis reaction conducted under the microwave condition is conducted for 1 min, at 100-230° C., under the pressure of 3-15 MPa.

7. The method for preparing the taurine according to claim 1, wherein the ammonolysis reaction conducted under the microwave condition is conducted for 10 min, at 100-230° C., under the pressure of 3-15 MPa.

8. The method for preparing the taurine according to claim 1, wherein the ammonolysis reaction conducted under the microwave condition is conducted for 5 min, at 100-150° C., under the pressure of 6 MPa.

9. The method for preparing the taurine according to claim 1, wherein a molar ratio of the isethionate to the ammonia is 1:1-1:15.

10. The method for preparing the taurine according to claim 1, wherein a molar ratio of the isethionate to the ammonia is 1:3-1:15.

11. The method for preparing the taurine according to claim 1, wherein a molar ratio of the isethionate to the ammonia is 1:5-1:10.

12. The method for preparing the taurine according to claim 9, wherein the concentration of the isethionate is 20 m/v % - 55 m/v %.

13. The method for preparing the taurine according to claim 9, wherein the concentration of the isethionate is 30 m/v % - 45 m/v %.

14. The method for preparing the taurine according to claim 12, wherein the concentration of the ammonia is 5 m/v % - 28 m/v %.

15. The method for preparing the taurine according to claim 12, wherein the concentration of the ammonia is 10 m/v % - 25 m/v %.

16. The method for preparing the taurine according to claim 1, wherein the isethionate is sodium isethionate, ammonium isethionate, potassium isethionate or lithium isethionate.

17. The method for preparing the taurine according to claim 1, wherein the ammonolysis reaction conducted under the microwave condition is completed in an intermittent reaction kettle, or is a continuous microwave reaction.

18. The method for preparing the taurine according to claim 1, wherein the obtained finished taurine product is of a columnar crystal form.

19. The method for preparing the taurine according to claim 1, comprising the following steps: S1: reacting ethylene oxide with a hydrogen sulfite solution to obtain the isethionate; S2: mixing the isethionate obtained in the Si and ammonia to obtain a reaction liquid; S3: subjecting the reaction liquid in the S2 to an ammonolysis reaction under the microwave action; S4: after the ammonolysis reaction, removing the excess ammonia, converting the obtained taurine salt into taurine, and conducting crystallization and separation to obtain a taurine product and a mother liquor; and S5: recycling the mother liquor to the S2.

20. The method for preparing the taurine according to claim 19, wherein the taurine salt is converted into the taurine through acidification, ion exchange, contact with an ion membrane, or heating.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) The specific content of the present invention is further described in detail by the following specific embodiments, and the examples are only used to explain the present invention, but not to limit the scope of the present invention.

(2) To illustrate the technical effect of the preparation method of the present invention, examples are given below. The raw materials used in the following embodiments are all commercially available products unless otherwise specified, the methods used are all conventional methods unless otherwise specified, and unless otherwise specified, the material content refers to mass volume percentage. A high-pressure closed microwave reactor used in the embodiments is existing equipment and the working frequency is selected as 2450 MHZ, but other suitable working frequencies are not limited. Aftertreatment refers to the above step S4, and the taurine salt is converted into the taurine by any methods which are not limited. The following embodiments select the ion exchange resin treatment method.

Embodiment 1

(3) 0.16 mol of sodium isethionate was dissolved in 125 ml (2.21 mol) of ammonia water of 30%, then the solution was added into a high-pressure closed microwave reactor to be subjected to a reaction at 230° C., 200° C. and 150° C. respectively for 0.5 minute, ammonia was removed after the reaction, taurine was extracted through aftertreatment, and mother liquor after purification was used indiscriminately in the ammonolysis reaction again. The results are shown in Table 1.

(4) TABLE-US-00001 TABLE 1 Data of microwave reaction for 0.5 minute at different reaction temperatures Microwave Microwave Total yield of Residual Microwave reaction reaction Yield of taurine after content of Serial reaction temperature pressure sodium indiscriminate sodium number time min ° C. MPa taurate use isethionate 1 0.5 230 15 93.83% 96.24% 0.25% 2 0.5 200 10 92.97% 95.86% 0.35% 3 0.5 150 6 92.11% 95.11% 0.40%

(5) The above experimental results show that the reaction time is set as 0.5 min, the pressure is set between 6 MPa and 15 MPa and the temperature is set between 150° C. and 230° C., the yield of the sodium taurate exceeds 92%, and the residual quantity of the sodium isethionate is less than 0.4%; therefore, the reaction time is greatly shortened, and the reaction temperature and the reaction pressure are reduced.

Embodiment 2

(6) 0.16 mol of sodium isethionate was dissolved in 125 ml of ammonia water of 30%, then the solution was added into a high-pressure closed microwave reactor to be subjected to a reaction at 230° C., 200° C., 150° C. and 100° C. respectively for 1 min, ammonia was removed after the reaction, taurine was extracted through aftertreatment, and mother liquor after purification was used indiscriminately in the ammonolysis reaction again. The results are shown in Table 2.

(7) TABLE-US-00002 TABLE 2 Data of microwave reaction for 1 minute under different temperatures and pressures Microwave Microwave Total yield of Residual Microwave reaction reaction Yield of taurine after content of Serial reaction temperature pressure sodium indiscriminate sodium number time min ° C. MPa taurate use isethionate 1 1 230 15 96.82% 97.57% 0.20% 2 1 200 10 96.40% 97.40% 0.28% 3 1 150 6 95.54% 97.39% 0.35% 4 1 100 3 95.11% 97.78% 0.40%

(8) The above experimental results show that the reaction time is set as 1 minute, the pressure is set between 3 MPa and 15 MPa and the temperature is set between 100° C. and 230° C., the yield of the sodium taurate exceeds 95%, and the residual quantity of the sodium isethionate is less than 0.4%; therefore, it indicates that the reaction is complete, the reaction time is greatly shortened, and the reaction temperature and the reaction pressure are reduced. Meanwhile, it also indicates that the ammonolysis reaction does not need to be conducted at the reaction temperature of 150° C. or above under the reaction pressure of 6 MPa or above, and a very high yield can also be obtained.

Embodiment 3

(9) 0.16 mol of sodium isethionate was dissolved in 125 ml of ammonia water of 30%, then the solution was added into a high-pressure closed microwave reactor to be subjected to a reaction at 230° C., 200° C., 150° C., 100° C., 80° C. and 50° C. respectively for 10 min, ammonia was removed after the reaction, taurine was extracted through aftertreatment, and mother liquor after purification was used indiscriminately in the ammonolysis reaction again. The results are shown in Table 3.

(10) TABLE-US-00003 TABLE 3 Data of microwave reaction for 10 minutes under different temperatures and pressures Microwave Microwave Total yield of Residual Microwave reaction reaction Yield of taurine after content of Serial reaction temperature pressure sodium indiscriminate sodium number time min ° C. MPa taurate use isethionate 1 10 230 15 96.40% 97.26% <0.1% 2 10 200 10 97.25% 97.98% <0.1% 3 10 150 6 97.68% 98.01% <0.1% 4 10 100 3 97.25% 97.32% <0.1% 5 10 80 1  96.0%  97.5% <0.1% 6 10 50 0.1 95.01% 97.68% <0.1%

(11) The above experimental results show that the reaction time is set as 10 minutes, the pressure is set between 3 MPa and 15 MPa and the temperature is set between 100° C. and 230° C., the yield of the sodium taurate exceeds 95%, and the residual quantity of the sodium isethionate is less than 0.1%; therefore, the reaction time is greatly shortened, and the reaction temperature and the reaction pressure are reduced. Meanwhile, it also indicates that under the condition of the reaction time, the yield of the sodium taurate is basically the same and exceeds 97% at the reaction temperature of 100° C. to 200° C. and under the pressure of 3 MPa to 10 MPa, and the total yield of the taurine after indiscriminate use also exceeds 97% and the reaction is complete.

Embodiment 4

(12) 0.16 mol of sodium isethionate was dissolved in 125 ml of ammonia water of 30%, then the solution was added into a high-pressure closed microwave reactor to be subjected to a reaction at 230° C., 200° C., 150° C. and 100° C. respectively for 35 min, ammonia was removed after the reaction, taurine was extracted through aftertreatment, and mother liquor after purification was used indiscriminately in the ammonolysis reaction again. The results are shown in Table 4.

(13) TABLE-US-00004 TABLE 4 Data of microwave reaction for 35 minutes at different temperatures Microwave Microwave Total yield of Residual Microwave reaction reaction Yield of taurine after content of Serial reaction temperature pressure sodium indiscriminate sodium number time min ° C. MPa taurate use isethionate 1 35 230 15 89.97% 96.17% <0.1% 2 35 200 10 90.83% 96.69% <0.1% 3 35 150 6 93.40% 97.09% <0.1% 4 35 100 3 95.11% 96.75% <0.1%

(14) The above experimental results show that the reaction time is set as 35 minutes, the pressure is set between 3 MPa and 15 MPa and the temperature is set between 100° C. and 230° C., and the residual quantity of the sodium isethionate is less than 0.1%. Compared with the shorter reaction time in the embodiments 1, 2, 3 and 5, the yield of the sodium taurine is reduced overall.

(15) It is also found that after the reaction time reaches a certain degree, the lower the reaction temperature is, the higher the yield of the taurine is. That is, when the reaction time is increased to a certain degree and the reaction temperature is 100° C., compared with the higher temperature such as 150° C., 200° C. and the like, the yield of the sodium taurine is higher.

Embodiment 5

(16) (1) 0.16 mol of sodium isethionate was added into 2.21 mol, 1.76 mol, 0.88 mol and 0.44 mol of ammonia, respectively, a certain amount of water was added, then each solution was added into a high-pressure closed microwave reactor to be subjected to a reaction at 150° C. and under the reaction pressure of 6 MPa for 5 minutes, ammonia was removed after the reaction, the taurine was extracted through aftertreatment, and mother liquor after purification was used indiscriminately in the ammonolysis reaction again. The results are shown in Table 5 (serial numbers 1-4).

(17) (2) 0.16 mol of sodium isethionate was added into 1.76 mol and 0.8 mol of ammonia, respectively, a certain amount of water was added, then each solution was added into a high-pressure closed microwave reactor to be subjected to a reaction at 100° C. and under the reaction pressure of 6 MPa for 5 minutes, ammonia was removed after the reaction, the taurine was extracted through aftertreatment, and mother liquor after purification was used indiscriminately in the ammonolysis reaction again. The results are shown in Table 5 (serial numbers 5-6).

(18) TABLE-US-00005 TABLE 5 Data of reaction for 5 minutes at different ammonia ratios and concentrations Microwave Total yield of Residual Microwave reaction Ammonia/sodium Yield of taurine after content of Serial reaction temperature isethionate sodium indiscriminate sodium number time min ° C. (molar ratio) taurate use isethionate 1 5 150 14 98.54% 99.04% <0.1% 2 5 150 11 98.11% 98.41% <0.1% 3 5 150 6 97.68% 99.18% <0.1% 4 5 150 3 92.11% 93.45% <0.1% 5 5 100 11 98.13%  98.5% <0.1% 6 5 100 5 97.65% 99.05% <0.1%

(19) The above experimental results show that when the reaction time is set as 5 minutes and the temperature is 150° C., the reaction effect is better when the molar ratio of ammonia to sodium isethionate exceeds 1:3, and the yield of the sodium taurate may reach 97.65% when the molar ratio is 1:5.

(20) As can be seen from the experimental result of different microwave reaction time in the embodiments 1-5, the result of the reaction for 5 minutes is that the residual quantity of the sodium isethionate is low and the reaction is very complete. As comparison between 1 minute and 5 minutes, the reaction yield shows an increasing tendency; when the reaction time is 10 minutes, the yield of the taurine has been slightly reduced; and when the reaction time is 35 minutes, the yield is reduced obviously. Therefore, it indicates that the ammonolysis reaction under microwave is very fast and the reaction time may be greatly reduced.

Embodiment 6

(21) Comparative experiment of crystal forms of the products obtained by different processes: (1) In the sodium taurate solution obtained in each group of experiment in the above embodiments 1-5, treatment was conducted by an ion exchange method after ammonia removal to obtain a taurine solution, concentration and crystallization were conducted to obtain a taurine crude product, then the crude product was decolored, recrystallized, separated and dried to obtain a finished product taurine, and mother liquor after centrifugation may be recycled and crystallized together with the crude product. The crystal form of the finished product taurine was sieved, and the result shows that the taurine is of the columnar crystal form. Two groups of experiment data with the serial numbers 1 and 2 in the embodiment 5 are taken as examples for description, as shown in Table 6. (2) According to the conventional production process, sodium isethionate (1 mol), sodium hydroxide and ammonia (14 mol) were mixed and heated to 250° C. in a high-pressure reaction kettle, a reaction was conducted under the reaction pressure of 15 MPa for 60 minutes to prepare a sodium taurate solution, ion exchange treatment was conducted after ammonia removal to obtain a taurine solution, concentration and crystallization were conducted to obtain a taurine crude product, the crude product was decolored and recrystallized, separation and drying were conducted to obtain a finished product taurine, and mother liquor after centrifugation may be recycled and crystallized together with the crude product. The crystal form of the finished product taurine was sieved, and the specific data is shown in Table 6.

(22) TABLE-US-00006 TABLE 6 Product crystal form data Less More Serial than 40- 40-60- 60-80- 80-100- 100-120- 120-150- than 150- number mesh mesh mesh mesh mesh mesh mesh Appearance note 1 43.60% 19.60% 7.20% 14.50% 6.00% 5.30% 3.30% Columnar Microwave reaction 2 49.80% 17.30% 7.30%  9.10% 5.70% 4.80% 5.90% Columnar Microwave reaction 3 28.40% 18.80% 9.60% 19.80% 8.30% 6.80% 7.80% Needle- Conventional like reaction

(23) It can be seen from the above experimental result that the crystal form of the finished product taurine obtained by the ammonolysis reaction under the microwave condition is columnar, and the finished product taurine obtained by the prior art is of a needle-like crystal form.

Embodiment 7

(24) Comparative example: comparative experiment using a conventional catalyst 0.16 mol of sodium isethionate is dissolved into 125 ml of ammonia of 30%, 0.02 mol of sodium hydroxide was added, and after mixing, the mixture was added into a high-pressure closed microwave reactor to be subjected to a reaction at 220° C. for 30 minutes, 60 minutes and 90 minutes respectively. The result of the ammonolysis reaction is as follows and the result is shown in Table 7.

(25) TABLE-US-00007 TABLE 7 Comparative reaction using the conventional catalyst at different time Conventional Conventional Molar quantity Residual Conventional reaction reaction Yield of of sodium content of Serial reaction time temperature pressure sodium hydroxide sodium number min ° C. MPa taurate (mol) isethionate 1 30 220 12 43.0% 0.015 19.80% 2 60 220 12 54.0% 0.015 15.60% 3 90 220 12 91.0% 0.015  3.50%

(26) It can be seen from the above experiment that according to the preparation method for adding the catalyst in the ammonolysis reaction in the prior art, when the reaction temperature is 220° C. and the reaction pressure is 12 MPa, the yield increases along with the increase of the reaction time. When the reaction time is set as 30 minutes, the yield of the sodium taurate is 43%; and when the reaction time is set as 90 minutes, the yield of the sodium taurate only reaches 91%.

(27) It can be clearly seen from the above embodiments that the patent method of the present invention can obviously increase the ammonolysis yield, the byproduct is obviously reduced and the reaction is more complete; meanwhile, the time, temperature and pressure required by the reaction are greatly reduced, and when the reaction time is 1-10 minutes, the total yield of the taurine may reach 95% or above. Furthermore, the crystal form of the finished product taurine is a columnar crystal form, which has been changed fundamentally, and the columnar granules are larger and firmer, so that the problem of short agglomeration time of the product is solved. The patent method of the present invention is a chemical process method which is green, environmentally friendly, simple and efficient.

(28) Finally, it should be noted that the foregoing embodiments are only used to explain the technical solutions of the present invention, and are not intended to limit the present invention. Although the present invention is described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or replace the preparation reaction condition, or make equivalent substitutions on some technical features therein. These modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.