A method for preparing inositol

Abstract

The present invention provides a method for preparing inositol, comprising the following steps: (1) uniformly mixing phytic acid and a catalyst, and placing the mixture into a microwave reactor, with a vacuum system equipped above the reactor; (2) turning on the microwave reactor to carry out the reaction, controlling the reaction temperature between 130 and 200 °C, and controlling the pressure between -0.05 and -0.09 MPa; (3) removing the gas-phase components generated during the reaction from the reaction system through the vacuum system, condensing them into a liquid phase, and collecting them after cooling; (4) the reaction time in step (2) is 2 to 8 h. When the liquid phase in step (3) no longer increases, cool down and stop the reaction; (5) quickly dissolve the materials in the reactor with deionized water, filter to obtain a filtrate and a filter cake. The filter cake is the catalyst, which can be reused after washing and drying; (6) cool down and crystallize the filtrate obtained in step (5), filter, wash, and dry to obtain the crude inositol. The crude product is purified to obtain the inositol product.

Description

Technical Field

[0001] The present invention relates to the field of inositol preparation, and in particular to a method for preparing inositol using phytic acid calcium. Background Art

[0002] Inositol (myo-inositol), also known as cyclohexanehexol, has the same relative molecular weight as glucose, which is 180.16, and its molecular formula is C6H 12 O6, which is an isomer of glucose. Under normal temperature, inositol is an odorless, slightly sweet white powdery crystal with a relatively high melting point of 225°C - 227°C and a density of 1.725 g / cm 3 (15°C), is easily soluble in water, slightly soluble in ethanol and acetonitrile, and almost insoluble in ether.

[0003] Inositol has a wide range of uses in the medical field, food field, and feed industry. Due to its biological activity and broad application prospects, inositol has been mass-produced and widely used in multiple industries. Currently, the production methods of inositol include the common phytic acid salt hydrolysis method, chemical synthesis method, enzyme catalysis method, and microbial method, etc.

[0004] The current production process for preparing inositol is to first pass corn steep liquor through a weakly basic resin column, then desorb the phytic acid adsorbed on the resin with strong acid, obtain a phytic acid solution, neutralize it with a water slurry prepared from calcium oxide, then filter to remove most of the calcium chloride, obtain a phytic acid calcium cake, then hydrolyze it at high temperature and filter to obtain a calcium phosphate cake and an inositol filtrate. The inositol filtrate undergoes concentration, crystallization, and filtration operations to obtain inositol products. However, the existing production process has a low inositol yield, a large amount of wastewater, and harsh conditions.

[0005] CN 110643643 B discloses a process for preparing inositol using phytic acid calcium, including (1) phytic acid calcium pulping; (2) hydrolysis; (3) lime milk neutralization, filtration and concentration; (4) crystallization and centrifugation; (5) decolorization; (6) refining. This process shortens the hydrolysis time of phytic acid calcium, improves the inositol yield, and can also obtain a single by-product, bringing economic benefits. However, there are more by-products and the process is complex. Summary of the Invention

[0006] The object of the present invention is to provide a method for preparing inositol, which does not use lime slurry, has few by-products, is easy to operate, has a high product purity, and can well solve the deficiencies of the existing technology.

[0007] To achieve the above object, the present invention provides a method for preparing inositol, including the following steps:

[0008] (1) Mix phytic acid calcium and a catalyst evenly, put them into a microwave reactor, and a vacuum system is equipped above the reactor;

[0009] (2) Turn on the microwave reactor, start heating, and carry out the reaction. The reaction temperature is controlled between 130 and 200 °C. At the same time, turn on the vacuum system and control the pressure between -0.05 and -0.09 MPa;

[0010] (3) Remove the gas-phase components generated during the reaction from the reaction system through the vacuum system, condense them into a liquid phase, cool down and collect;

[0011] (4) The reaction time in step (2) is 2 to 8 h. When the liquid phase in step (3) no longer increases, cool down and stop the reaction;

[0012] (5) Rapidly dissolve the materials in the reactor with deionized water, filter to obtain a filtrate and a filter cake. The filter cake is the catalyst, which can be reused after washing and drying;

[0013] (6) Cool down and crystallize the filtrate obtained in step (5), filter, wash, and dry to obtain crude inositol. The crude product is purified to obtain inositol product.

[0014] By setting up the vacuum system, the phosphoric acid generated by the reaction can be removed from the reaction system, promoting the reaction to proceed in the forward reaction direction and making the reaction proceed thoroughly.

[0015] Further, in step (1), the power of the microwave reactor is 0 to 3000 W, and the temperature range is 0 to 500 °C.

[0016] Further, in step (1), the mass ratio of phytic acid to the catalyst is 30 to 100:1.

[0017] Further, in step (3), the liquid phase is crude phosphoric acid, and the obtained crude phosphoric acid can be used as a by-product after purification.

[0018] Further, in step (1), the catalyst is one of hydrogen-type β zeolite, WO 3 / ZrO2 solid acid, SO4 2- / ZrO2 solid acid. After using the catalyst, the reaction rate is accelerated, which is beneficial to the progress of the reaction.

[0019] Further, in step (1), the particle sizes of both phytic acid and the catalyst are between 100 and 200 mesh. If the particle size is too large, it will affect the contact of the materials and the reaction effect will become worse.

[0020] Further, in step (1), catalytic assistant sodium carbonate is added. The addition amount of sodium carbonate is 5 to 10% of the mass of the catalyst, and the particle size of sodium carbonate is between 100 and 200 mesh. Adding sodium carbonate can react with the phosphoric acid generated by the reaction at the initial stage of the reaction, initiate the reaction, and promote the reaction to proceed faster.

[0021] Further, the purification method in step (6) is that the crude inositol is dissolved in deionized water, then ethanol is added, solids are precipitated, filtered, washed, and dried to obtain an inositol product with a product purity > 99.5%.

[0022] Further, the purification method in step (6) is that the crude inositol is dissolved in deionized water, then sodium chloride is added, solids are precipitated, filtered, washed, and dried to obtain an inositol product with a product purity > 99.7%.

[0023] Further, the purification method in step (6) is that the crude inositol is dissolved in deionized water, cooled, and solids accounting for 40 - 50% of the total mass of the product are precipitated, filtered, then ethanol is added, and solids accounting for 50 - 60% of the total mass of the product are precipitated. The solids precipitated twice are combined, washed, and dried to obtain an inositol product with a product purity > 99.9%. Precipitating the solids in two steps can reduce the encapsulation of impurities in the product and improve the product purity.

[0024] The present invention provides a preparation method of inositol, and the prepared product has a purity greater than 99.5%, which can meet the applications in various fields. Specific embodiments

[0025] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0026] Example 1

[0027] A preparation method of inositol includes the following steps:

[0028] (1) Mix phytic acid and a catalyst with a mass ratio of 80:1, both with particle sizes between 100 and 200 mesh, evenly, put them into a microwave reactor, and a vacuum system is equipped above the reactor. The catalyst is hydrogen - type β zeolite;

[0029] (2) Turn on the microwave reactor, start heating, and carry out the reaction. The reaction temperature is controlled between 170 and 200 °C. At the same time, turn on the vacuum system, control the pressure between - 0.05 and - 0.07 MPa. The power of the microwave reactor is 0 - 3000 W, and the temperature range is 0 - 500 °C. Adjust the power according to the temperature requirement;

[0030] (3) Remove the gas - phase components generated during the reaction from the reaction system through the vacuum system, condense them into a liquid phase, and the liquid phase is crude phosphoric acid, which is cooled and collected;

[0031] (4) The reaction time in step (2) is 8 h. When the liquid phase in step (3) no longer increases, cool down and stop the reaction;

[0032] (5) Rapidly dissolve the materials in the reactor with deionized water, filter to obtain a filtrate and a filter cake. The filter cake is the catalyst, which can be reused after washing and drying;

[0033] (6) Cool the filtrate obtained in step (5) for crystallization, filter, wash, and dry to obtain crude inositol. Dissolve the crude inositol in deionized water, then add ethanol to precipitate solids. Filter, wash, and dry to obtain the inositol product with a yield of 97.3% and a purity of 99.52%.

[0034] Example 2

[0035] A method for preparing inositol, comprising the following steps:

[0036] (1) Mix 35:1 phytic acid and a catalyst with particle sizes all between 100 and 200 mesh, and 8% by mass of sodium carbonate with a particle size between 100 and 200 mesh based on the mass of the catalyst. Mix them evenly and place them in a microwave reactor. A vacuum system is equipped above the reactor. The catalyst is WO 3 / ZrO2 solid acid;

[0037] (2) Turn on the microwave reactor, start heating, and carry out the reaction. Control the reaction temperature between 160 and 180 °C. At the same time, turn on the vacuum system and control the pressure between -0.07 and -0.09 MPa. The power of the microwave reactor is 0 - 3000 W, and the temperature range is 0 - 500 °C. Adjust the power according to the temperature requirement;

[0038] (3) Remove the gas-phase components generated during the reaction from the reaction system through the vacuum system and condense them into a liquid phase. The liquid phase is crude phosphoric acid, which is cooled and collected;

[0039] (4) The reaction time in step (2) is 2 h. When the liquid phase in step (3) no longer increases, cool down and stop the reaction;

[0040] (5) Rapidly dissolve the materials in the reactor with deionized water, filter to obtain a filtrate and a filter cake. The filter cake is the catalyst, which can be reused after washing and drying;

[0041] (6) Cool the filtrate obtained in step (5) for crystallization, filter, wash, and dry to obtain crude inositol. Dissolve the crude inositol in deionized water, cool down, and precipitate solids with a total mass of 40 - 50% of the product. Filter, then add ethanol to precipitate solids with a total mass of 50 - 60% of the product. Combine the solids precipitated twice, wash, and dry to obtain the inositol product with a yield of 98.2% and a purity of 99.93%.

[0042] Example 3

[0043] A method for preparing inositol, comprising the following steps:

[0044] (1) Mix phytic acid and a catalyst with a mass ratio of 50:1, both having a particle size between 100 and 200 mesh, evenly, and place them in a microwave reactor. A vacuum system is equipped above the reactor. The catalyst is SO4 2- / ZrO2 solid acid;

[0045] (2) Turn on the microwave reactor, start heating, and conduct the reaction. Control the reaction temperature between 160 and 180 °C. At the same time, turn on the vacuum system and control the pressure between -0.07 and -0.09 MPa. The power of the microwave reactor is 0 - 3000 W, and the temperature range is 0 - 500 °C. Adjust the power according to the temperature requirement;

[0046] (3) Remove the gas-phase components generated during the reaction from the reaction system through the vacuum system and condense them into a liquid phase. The liquid phase is crude phosphoric acid, which is cooled and collected;

[0047] (4) The reaction time in step (2) is 6 h. When the liquid phase in step (3) no longer increases, cool down and stop the reaction;

[0048] (5) Rapidly dissolve the materials in the reactor with deionized water, filter to obtain a filtrate and a filter cake. The filter cake is the catalyst, which can be reused after washing and drying;

[0049] (6) Cool down and crystallize the filtrate obtained in step (5), filter, wash, and dry to obtain crude inositol. Dissolve the crude inositol in deionized water, then add sodium chloride, precipitate solids, filter, wash, and dry to obtain inositol products with a yield of 97.1% and a purity of 99.76%.

[0050] Comparative Example 1

[0051] The difference between Comparative Example 1 and Example 2 is that the vacuum system is removed. The final yield of the inositol product is 13.1% and the purity is 51.2%. The other conditions are the same as in Example 2 and will not be elaborated. This shows that the removal of phosphoric acid during the reaction has a decisive influence on the reaction.

[0052] Comparative Example 2

[0053] The difference between Comparative Example 2 and Example 2 is that the addition of sodium carbonate in step (1) is removed. The other conditions are the same as in Example 2 and will not be elaborated. The final yield of the inositol product is 88.4% and the purity is 99.51%. When the reaction time is extended to 5 h, the yield is increased to 97.9%. This shows that adding sodium carbonate can react with the phosphoric acid generated during the reaction at the initial stage of the reaction, initiate the reaction, promote the reaction to proceed faster, and reduce the reaction time.

[0054] Comparative Example 3

[0055] The difference between Comparative Example 3 and Example 1 is that the addition of the catalyst in step (1) is removed, and the rest is the same as Example 1, which will not be elaborated here. The final yield of the inositol product is 35.3% and the purity is 62.1%. It shows that the addition of the catalyst is necessary for the reaction to proceed smoothly.

[0056] Comparative Example 4

[0057] The difference between Comparative Example 3 and Example 1 is that the heating method is changed to ordinary oil bath heating, and the rest is the same as Example 1, which will not be elaborated here. The final yield of the inositol product is 79.2% and the purity is 86.5%. It shows that microwave has a good promoting effect on the reaction.

Claims

1. A method for preparing inositol, comprising the following steps: (1) Mix phytic acid and a catalyst evenly, put them into a microwave reactor, and a vacuum system is equipped above the reactor; (2) Turn on the microwave reactor, start heating, and carry out the reaction. The reaction temperature is controlled between 130 and 200 °C, and at the same time, turn on the vacuum system to control the pressure between -0.05 and -0.09 MPa; (3) Remove the gas-phase components generated during the reaction from the reaction system through the vacuum system, condense them into a liquid phase, cool down and collect; (4) The reaction time in step (2) is 2 to 8 h. When the liquid phase in step (3) no longer increases, cool down and stop the reaction; (5) Quickly dissolve the materials in the reactor with deionized water, filter to obtain a filtrate and a filter cake. The filter cake is the catalyst, which can be reused after washing and drying; (6) Cool down and crystallize the filtrate obtained in step (5), filter, wash, and dry to obtain crude inositol, and the crude product is purified to obtain inositol product; In step (1), a catalytic auxiliary sodium carbonate is added, and the addition amount of sodium carbonate is 5 to 10% of the mass of the catalyst, and the particle size of sodium carbonate is between 100 and 200 mesh; In the step (1), the catalyst is one of hydrogen-form β zeolite, WO 3 / ZrO2 solid acid, SO4 2- / ZrO2 solid acid 2. The preparation method according to claim 1, wherein In step (1), the power of the microwave reactor is 0 to 3000 W, and the temperature range is 0 to 500 °C.

3. The preparation method according to claim 1, wherein, In step (1), the mass ratio of phytic acid to the catalyst is 30 to 100:

1.

4. The preparation method according to claim 1, wherein, In step (3), the liquid phase is crude phosphoric acid.

5. The preparation method according to claim 1, characterized in that, In step (1), the particle sizes of phytic acid and the catalyst are both between 100 and 200 mesh.

6. The preparation method according to claim 1, characterized in that, The purification method in step (6) is that the crude inositol is dissolved in deionized water, then ethanol is added, solids are precipitated, filtered, washed, and dried to obtain inositol product.

7. The preparation method according to claim 1, wherein The purification method in step (6) is that the crude inositol is dissolved in deionized water, then sodium chloride is added, solids are precipitated, filtered, washed, and dried to obtain inositol product.

8. The preparation method according to claim 1, characterized in that, The purification method in step (6) is that the crude inositol is dissolved in deionized water, cooled down, and solids accounting for 40 to 50% of the total mass of the product are precipitated, filtered, then ethanol is added, and solids accounting for 50 to 60% of the total mass of the product are precipitated. The solids precipitated twice are combined, washed, and dried to obtain inositol product.