Method for preparing monopotassium phosphate from potassium phytate and monopotassium phosphate

Abstract

The invention discloses a method for preparing monopotassium phosphate from potassium phytate and the monopotassium phosphate, relates to the technical field of preparation of the monopotassium phosphate, and aims to solve the technical problems of poor quality, low yield and complex process of the monopotassium phosphate prepared from the potassium phytate in the prior art. The method for preparing monopotassium phosphate from potassium phytate comprises the following steps: obtaining a potassium phytate solution containing calcium and magnesium ion impurities; hydrolyzing the potassium phytate solution under the condition that the pH value is 5-7 to obtain hydrolysate, and filtering the hydrolysate at 50-65 DEG C to obtain filtrate and a filter cake; adding phytic acid hydrolysate into the filtrate to adjust the pH value to 3.0-3.8, and performing chromatographic separation on the filtrate to obtain a monopotassium phosphate phase and an inositol phase; concentrating the monopotassium phosphate phase until the solid content is 55-65wt%, filtering, and drying a filter cake to obtain a monopotassium phosphate product without calcium and magnesium ions. The technical scheme provided by the invention is used for preparing monopotassium phosphate.

Description

Technical Field

[0001] The invention relates to the technical field of potassium dihydrogen phosphate preparation, and in particular to a method for preparing potassium dihydrogen phosphate by utilizing potassium phytate and the potassium dihydrogen phosphate. Background Art

[0002] Potassium dihydrogen phosphate is an important product in the phosphate industry. It is widely used in agriculture, chemical industry, food and medicine, among which its application in agriculture is particularly prominent. Potassium dihydrogen phosphate is a highly efficient and high-concentration phosphorus-potassium compound fertilizer, and is also a harmless, non-toxic and residue-free green fertilizer.

[0003] In the existing process of preparing potassium dihydrogen phosphate using potassium phytate, the raw material potassium phytate will be accompanied by magnesium ions and calcium ions from corn soaking water, and the presence of these magnesium ions and calcium ions will reduce the quality of the obtained potassium dihydrogen phosphate, which cannot meet the actual needs, and is specifically manifested as a turbid state after potassium dihydrogen phosphate is dissolved in water, and floccules are produced. In the prior art, the calcium ions and magnesium ions in potassium dihydrogen phosphate are removed by direct filtration or sedimentation, but because magnesium ions and calcium ions are not completely precipitated in water, the removal effect is not ideal, and potassium dihydrogen phosphate is also dissolved, crystallized and dried again in the process, not only reducing the yield of potassium dihydrogen phosphate, but also separating magnesium ions and calcium ions. The process flow is cumbersome. Therefore, a new preparation method of potassium dihydrogen phosphate is urgently needed to solve the above problems. Summary of the invention

[0004] In order to solve the technical problems of poor quality and low yield of potassium dihydrogen phosphate prepared by potassium phytate in the prior art, as well as complicated process, the present invention provides a method for preparing potassium dihydrogen phosphate by using potassium phytate and potassium dihydrogen phosphate. In view of this, the present invention is implemented by the following technical scheme.

[0005] In a first aspect, the present invention provides a method for preparing potassium dihydrogen phosphate using potassium phytate, comprising:

[0006] obtaining a potassium phytate solution containing calcium and magnesium ion impurities;

[0007] The potassium phytate solution is hydrolyzed at a pH value of 5 to 7 to obtain a hydrolyzate, and the hydrolyzate is filtered at 50 to 65° C. to obtain a filtrate and a filter cake; wherein the filtrate is a mixed solution of potassium dihydrogen phosphate and inositol, and the filter cake is a mixture of magnesium hydrogen phosphate and calcium hydrogen phosphate;

[0008] Adding phytic acid hydrolyzate to the filtrate to adjust the pH value to 3.0-3.8, and subjecting the filtrate to chromatographic separation to obtain a potassium dihydrogen phosphate phase and an inositol phase;

[0009] The potassium dihydrogen phosphate phase is concentrated to a solid content of 55-65 wt %, filtered and the filter cake is dried to obtain a potassium dihydrogen phosphate product free of calcium and magnesium ions.

[0010] Compared with the prior art, in the method for preparing potassium dihydrogen phosphate using potassium phytate of the present invention, potassium phytate is hydrolyzed to obtain potassium dihydrogen phosphate and inositol. The pH value of the potassium phytate solution is controlled to be 5-7, a part of the calcium phytate in the potassium phytate solution forms calcium hydrogen phosphate during the hydrolysis process, and a part of the magnesium phytate forms magnesium hydrogen phosphate during the hydrolysis process, and by controlling the temperature of the hydrolyzate to be 55-65° C., the calcium hydrogen phosphate and magnesium hydrogen phosphate in the hydrolyzate can be precipitated, and the calcium hydrogen phosphate and magnesium hydrogen phosphate in the hydrolyzate can be removed by filtration to obtain a filtrate. Further, phytic acid hydrolyzate is added to the filtrate to adjust the pH value to 3.0-3.8, which can improve the solubility of residual calcium and magnesium ions in the filtrate. The phytic acid hydrolyzate is a mixed solution of phosphoric acid and inositol. The filtrate is subjected to chromatographic separation to obtain a potassium dihydrogen phosphate phase and an inositol phase containing residual calcium and magnesium ions. The potassium dihydrogen phosphate phase is concentrated to a solid content of 55-65wt%, so that a large amount of potassium dihydrogen phosphate in the potassium dihydrogen phosphate phase is crystallized and precipitated, and a potassium dihydrogen phosphate filter cake and a filtrate containing calcium and magnesium ions are obtained after filtration. The potassium dihydrogen phosphate filter cake is dried to obtain a potassium dihydrogen phosphate product free of calcium and magnesium ions. The above-mentioned technical scheme of the present invention is adopted to solve the technical problems of poor quality and low yield of potassium dihydrogen phosphate prepared by potassium phytate in the prior art, as well as complex process.

[0011] Furthermore, in the method for preparing potassium dihydrogen phosphate using potassium phytate of the present invention, the hydrolysis method includes high temperature and high pressure hydrolysis, phytase hydrolysis or microwave hydrolysis.

[0012] Furthermore, in the method for preparing potassium dihydrogen phosphate using potassium phytate of the present invention, the hydrolysis method adopts high temperature and high pressure hydrolysis, and the high temperature and high pressure hydrolysis process is:

[0013] The potassium phytate solution is added into a hydrolysis kettle, and hydrolyzed for 6 to 10 hours at a temperature of 160 to 200°C and a pressure of 0.6 to 1 MPa to obtain the hydrolyzate.

[0014] Furthermore, in the method for preparing potassium dihydrogen phosphate using potassium phytate of the present invention, the step of concentrating the potassium dihydrogen phosphate phase to a solid content of 55 to 65 wt% comprises:

[0015] The potassium dihydrogen phosphate phase is concentrated to a solid content of 55-65 wt %, and the temperature is lowered to 30-40° C. to precipitate the potassium dihydrogen phosphate, and filtered to obtain a first potassium dihydrogen phosphate filtrate and a first potassium dihydrogen phosphate filter cake;

[0016] The first potassium dihydrogen phosphate filtrate is then concentrated to a solid content of 55-65 wt %, and the temperature is lowered to 30-40° C. to precipitate the potassium dihydrogen phosphate, and filtered to obtain a second potassium dihydrogen phosphate filtrate and a second potassium dihydrogen phosphate filter cake;

[0017] The first potassium dihydrogen phosphate filter cake and the second potassium dihydrogen phosphate filter cake are mixed and then dried to obtain the potassium dihydrogen phosphate product.

[0018] Furthermore, in the method for preparing potassium dihydrogen phosphate using potassium phytate of the present invention, the potassium phytate solution is hydrolyzed at a pH value of 5 to 7 to obtain a hydrolyzate, and the hydrolyzate is filtered at 55 to 65° C. to obtain a filtrate and a filter cake. Before adding the phytic acid hydrolyzate to the filtrate, the method further comprises:

[0019] Obtaining a phytic acid solution with a mass concentration of 15 to 25 wt%;

[0020] The phytic acid solution is added into a hydrolysis kettle, and hydrolyzed for 6 to 10 hours at a temperature of 160 to 200° C. and a pressure of 0.6 to 1.0 MPa to obtain the phytic acid hydrolyzate.

[0021] Furthermore, in the method for preparing potassium dihydrogen phosphate using potassium phytate of the present invention, after obtaining the potassium phytate solution containing calcium and magnesium ion impurities, before hydrolyzing the potassium phytate solution at a pH value of 5 to 7 to obtain a hydrolyzate, the method further comprises:

[0022] An alkaline substance is added to the potassium phytate solution to adjust the pH value of the potassium phytate solution to 5-7.

[0023] Furthermore, in the method for preparing potassium dihydrogen phosphate using potassium phytate of the present invention, the alkaline substance includes KOH, K2CO3 or KHCO3.

[0024] Furthermore, in the method for preparing potassium dihydrogen phosphate using potassium phytate of the present invention, after adding phytic acid hydrolyzate to the filtrate to adjust the pH value to 3.0-3.8, and before subjecting the filtrate to chromatographic separation, the method further comprises:

[0025] 1-5 wt % of activated carbon is added to the filtrate, and the mixture is stirred for 0.5-1 h at a temperature of 45-65° C. and a stirring rate of 20-100 rpm. The activated carbon is filtered out to obtain a decolorized filtrate.

[0026] In a second aspect, the present invention provides a potassium dihydrogen phosphate product, which is prepared according to the above method for preparing potassium dihydrogen phosphate using potassium phytate, wherein the potassium dihydrogen phosphate content in the potassium dihydrogen phosphate product is 99.0-99.5wt%, and the rest is impurities.

[0027] Compared with the prior art, the beneficial effects of the potassium dihydrogen phosphate product provided by the present invention are the same as the beneficial effects of the method for preparing potassium dihydrogen phosphate using potassium phytate described in the above technical scheme, and will not be described in detail here.

[0028] In a third aspect, the present invention provides a method for preparing inositol, which comprises the following steps:

[0029] The inositol phase is concentrated to dryness at a temperature of 70-100° C. and a stirring rate of 20-100 rpm to obtain an inositol product; wherein the inositol content in the inositol product is 99-99.8wt%, and the rest is impurities.

[0030] Compared with the prior art, the beneficial effects of the method for preparing inositol provided by the present invention are the same as the beneficial effects of the method for preparing potassium dihydrogen phosphate using potassium phytate described in the above technical scheme, and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0032] Figure 1 The present invention provides a schematic flow chart of a method for preparing potassium dihydrogen phosphate using potassium phytate according to Example 1 of the present invention. DETAILED DESCRIPTION

[0033] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0034] In the existing process of preparing potassium dihydrogen phosphate using potassium phytate, the raw material potassium phytate will carry magnesium ions and calcium ions from the corn soaking water. The presence of these magnesium ions and calcium ions will reduce the quality of the prepared potassium dihydrogen phosphate and cannot meet the actual needs. Specifically, the potassium dihydrogen phosphate is turbid after being dissolved in water, and floccules are produced. In the prior art, direct filtration or sedimentation is used to remove calcium ions and magnesium ions from potassium dihydrogen phosphate, but since the magnesium ions and calcium ions are not completely precipitated in water, the removal effect is not ideal, and the potassium dihydrogen phosphate must be dissolved, crystallized and dried again in the process, which not only reduces the yield of potassium dihydrogen phosphate, but also makes the process of separating magnesium ions and calcium ions cumbersome.

[0035] In order to solve the above technical problems, in a first aspect, the present invention provides a method for preparing potassium dihydrogen phosphate using potassium phytate, comprising:

[0036] obtaining a potassium phytate solution containing calcium and magnesium ion impurities;

[0037] The potassium phytate solution is hydrolyzed at a pH value of 5 to 7 to obtain a hydrolyzate, and the hydrolyzate is filtered at 50 to 65° C. to obtain a filtrate and a filter cake; wherein the filtrate is a mixed solution of potassium dihydrogen phosphate and inositol, and the filter cake is a mixture of magnesium hydrogen phosphate and calcium hydrogen phosphate;

[0038] Adding phytic acid hydrolyzate to the filtrate to adjust the pH value to 3.0-3.8, and subjecting the filtrate to chromatographic separation to obtain a potassium dihydrogen phosphate phase and an inositol phase;

[0039] The potassium dihydrogen phosphate phase is concentrated to a solid content of 55-65 wt %, filtered and the filter cake is dried to obtain a potassium dihydrogen phosphate product free of calcium and magnesium ions.

[0040] By adopting the above technical scheme, in the method for preparing potassium dihydrogen phosphate using potassium phytate of the present invention, potassium phytate is hydrolyzed to obtain potassium dihydrogen phosphate and inositol. The pH value of the potassium phytate solution is controlled to be 5-7, a part of the calcium phytate in the potassium phytate solution forms calcium hydrogen phosphate during the hydrolysis process, and a part of the magnesium phytate forms magnesium hydrogen phosphate during the hydrolysis process, and by controlling the temperature of the hydrolyzate to be 55-65° C., the calcium hydrogen phosphate and magnesium hydrogen phosphate in the hydrolyzate can be precipitated, and the calcium hydrogen phosphate and magnesium hydrogen phosphate in the hydrolyzate can be removed by filtration to obtain a filtrate. Furthermore, phytic acid hydrolyzate is added to the filtrate to adjust the pH value to 3.0-3.8, which can improve the solubility of residual calcium and magnesium ions in the filtrate. The phytic acid hydrolyzate is a mixed solution of phosphoric acid and inositol. The filtrate is subjected to chromatographic separation to obtain a potassium dihydrogen phosphate phase and an inositol phase containing residual calcium and magnesium ions. The potassium dihydrogen phosphate phase is concentrated to a solid content of 55-65wt%, so that a large amount of potassium dihydrogen phosphate in the potassium dihydrogen phosphate phase is crystallized and precipitated. After filtration, a potassium dihydrogen phosphate filter cake and a filtrate containing calcium and magnesium ions are obtained. The potassium dihydrogen phosphate filter cake is dried to obtain a potassium dihydrogen phosphate product free of calcium and magnesium ions.

[0041] It should be understood that in order to increase the hydrolysis rate of the potassium phytate solution, the present invention also needs to control the hydrolysis method of the potassium phytate solution. For example, the hydrolysis method includes high temperature and high pressure hydrolysis, phytase hydrolysis or microwave hydrolysis.

[0042] It should also be understood that when the potassium phytate solution is hydrolyzed by high temperature and high pressure hydrolysis, the present invention also needs to control the hydrolysis conditions of the potassium phytate solution, and the high temperature and high pressure hydrolysis process is: adding the potassium phytate solution to a hydrolysis kettle, and hydrolyzing it at a temperature of 160 to 200°C and a pressure of 0.6 to 1 MPa for 6 to 10 hours to obtain a hydrolyzate of the potassium phytate solution. For example, the temperature during the high temperature and high pressure hydrolysis can be 160°C, 180°C or 200°C, the pressure can be 0.6MPa, 0.8MPa or 1MPa, and the hydrolysis time can be 6h, 8h or 10h.

[0043] As a possible implementation manner, in the method for preparing potassium dihydrogen phosphate using potassium phytate of the present invention, the step of concentrating the potassium dihydrogen phosphate phase to a solid content of 55 to 65 wt% comprises:

[0044] The potassium dihydrogen phosphate phase is concentrated to a solid content of 55-65 wt %, and the temperature is lowered to 30-40° C. to precipitate the potassium dihydrogen phosphate, and filtered to obtain a first potassium dihydrogen phosphate filtrate and a first potassium dihydrogen phosphate filter cake;

[0045] The first potassium dihydrogen phosphate filtrate is then concentrated to a solid content of 55-65 wt %, and the temperature is lowered to 30-40° C. to precipitate the potassium dihydrogen phosphate, and filtered to obtain a second potassium dihydrogen phosphate filtrate and a second potassium dihydrogen phosphate filter cake;

[0046] The first potassium dihydrogen phosphate filter cake and the second potassium dihydrogen phosphate filter cake are mixed and then dried to obtain the potassium dihydrogen phosphate product.

[0047] By adopting the above technical solution, the potassium dihydrogen phosphate phase contains calcium and magnesium ions, and the potassium dihydrogen phosphate phase is concentrated to a solid content of 55-65wt%, and a potassium dihydrogen phosphate product and a filtrate containing calcium and magnesium ions can be obtained by filtration, thereby achieving the separation of potassium dihydrogen phosphate and calcium and magnesium ions. By adopting the above technical solution of step-by-step concentration, the separation effect of calcium and magnesium ions and potassium dihydrogen phosphate can be better, and a potassium dihydrogen phosphate product without calcium and magnesium ions can be obtained. Specifically, the potassium dihydrogen phosphate phase is first concentrated to 55-65wt% of potassium dihydrogen phosphate to precipitate, and after filtration, the calcium and magnesium ions in the potassium dihydrogen phosphate phase are present in the first potassium dihydrogen phosphate filtrate, and the first potassium dihydrogen phosphate filtrate still contains 35-45wt% of potassium dihydrogen phosphate; the first potassium dihydrogen phosphate filtrate is then concentrated to 55-65wt% of potassium dihydrogen phosphate to precipitate, and after filtration, the calcium and magnesium ions in the first potassium dihydrogen phosphate filtrate are present in the second potassium dihydrogen phosphate filtrate, and the first potassium dihydrogen phosphate filter cake and the second potassium dihydrogen phosphate filter cake obtained by the above step-by-step concentration are mixed and dried to obtain the potassium dihydrogen phosphate product containing 99.0-99.9wt% of potassium dihydrogen phosphate.

[0048] As a possible embodiment, in the method for preparing potassium dihydrogen phosphate using potassium phytate of the present invention, the potassium phytate solution is hydrolyzed at a pH of 5 to 7 to obtain a hydrolyzate, and the hydrolyzate is filtered at 55 to 65° C. to obtain a filtrate and a filter cake. Before adding the phytic acid hydrolyzate to the filtrate, the method further comprises:

[0049] Obtaining a phytic acid solution with a mass concentration of 15 to 25 wt%;

[0050] The phytic acid solution is added into a hydrolysis kettle, and hydrolyzed for 6 to 10 hours at a temperature of 160 to 200° C. and a pressure of 0.6 to 1.0 MPa to obtain the phytic acid hydrolyzate.

[0051] By adopting the above technical scheme, the phytic acid solution is hydrolyzed to obtain a phytic acid hydrolyzate, which is a strongly acidic solution containing phosphoric acid and inositol, and the phosphoric acid content in the phytic acid hydrolyzate is 13.36-22.27wt%, and the inositol content is 4.09-6.18wt%. After obtaining the phytic acid solution, the phytic acid solution is hydrolyzed at high temperature and high pressure to obtain the phytic acid hydrolyzate. The present invention can improve the hydrolysis efficiency of the phytic acid solution by controlling the concentration of the phytic acid solution, as well as the temperature, pressure and hydrolysis time of the phytic acid solution during hydrolysis, and obtain the phytic acid hydrolyzate that is completely hydrolyzed. For example, the concentration of the phytic acid solution can be 15wt%, 20wt% or 25wt%, the temperature during the hydrolysis can be 160℃, 180℃ or 200℃, the pressure during the hydrolysis can be 0.6MPa, 0.8MPa or 1MPa, and the hydrolysis time can be 6h, 8h or 10h.

[0052] As a possible implementation mode, in the method for preparing potassium dihydrogen phosphate using potassium phytate of the present invention, after obtaining the potassium phytate solution containing calcium and magnesium ion impurities, before hydrolyzing the potassium phytate solution at a pH value of 5 to 7 to obtain a hydrolyzate, the method further comprises:

[0053] An alkaline substance is added to the potassium phytate solution to adjust the pH value of the potassium phytate solution to 5-7.

[0054] By adopting the above technical solution, the potassium phytate solution is a strongly acidic solution, and the pH value of the potassium phytate solution can be adjusted to 5-7 by adding alkaline substances into the potassium phytate solution.

[0055] It should be understood that in the process of adding an alkaline substance to the potassium phytate solution to adjust the pH value of the potassium phytate solution to 5-7, in order to improve the efficiency of adjusting the pH value of the potassium phytate solution, it is also necessary to control the type of the alkaline substance. For example, the alkaline substance includes KOH, K2CO3 or KHCO3.

[0056] As a possible implementation mode, in the method for preparing potassium dihydrogen phosphate using potassium phytate of the present invention, after adding phytic acid hydrolyzate to the filtrate to adjust the pH value to 3.0-3.8, and before subjecting the filtrate to chromatographic separation, the method further comprises:

[0057] 1-5 wt % of activated carbon is added to the filtrate, and the mixture is stirred for 0.5-1 h at a temperature of 45-65° C. and a stirring rate of 20-100 rpm. The activated carbon is filtered out to obtain a decolorized filtrate.

[0058] By adopting the above technical scheme, the filtrate contains impurities such as pigments, and the activated carbon is added to the filtrate, and the amount of the activated carbon added, the temperature of the filtrate and the stirring rate are controlled, so as to improve the decolorization efficiency of the filtrate and obtain a filtrate free of pigments. For example, the amount of the activated carbon added can be 1wt%, 3wt% or 5wt%, the temperature of the filtrate can be 45°C, 55°C or 65°C, and the stirring rate can be 20rpm, 60rpm or 100rpm.

[0059] In a second aspect, the present invention provides a potassium dihydrogen phosphate product, which is prepared according to the above method for preparing potassium dihydrogen phosphate using potassium phytate, wherein the potassium dihydrogen phosphate content in the potassium dihydrogen phosphate product is 99.0-99.5wt%, and the rest is impurities.

[0060] Compared with the prior art, the beneficial effects of the potassium dihydrogen phosphate product provided by the present invention are the same as the beneficial effects of the method for preparing potassium dihydrogen phosphate using potassium phytate described in the above technical scheme, and will not be described in detail here.

[0061] In a third aspect, the present invention provides a method for preparing inositol, which comprises the following steps:

[0062] The inositol phase is concentrated to dryness at a temperature of 70-100° C. and a stirring rate of 20-100 rpm to obtain an inositol product; wherein the inositol content in the inositol product is 99-99.8wt%, and the rest is impurities.

[0063] Compared with the prior art, the beneficial effects of the method for preparing inositol provided by the present invention are the same as the beneficial effects of the method for preparing potassium dihydrogen phosphate using potassium phytate described in the above technical scheme, and the temperature and stirring rate during concentration are controlled at the same time, so as to improve the concentration efficiency of the inositol phase and obtain a high-quality inositol product.

[0064] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with specific embodiments, but the content of the present invention is not limited to the following embodiments.

[0065] Unless otherwise specified, the raw materials used in the following examples are commercially available.

[0066] Example 1

[0067] This embodiment provides a method for preparing potassium dihydrogen phosphate using potassium phytate, comprising the following steps:

[0068] S100, obtaining 2000 g of a potassium phytate solution; wherein the potassium phytate solution has a calcium ion content of 200 ppm and a magnesium ion content of 2000 ppm;

[0069] S200, adding KOH to the potassium phytate solution while stirring to adjust the pH value of the potassium phytate solution to 5; then adding the potassium phytate solution to a hydrolysis kettle, and hydrolyzing it at a temperature of 160° C. and a pressure of 0.6 MPa for 10 hours to obtain a hydrolyzate of the potassium phytate solution; cooling the hydrolyzate to 50° C. and filtering to obtain a filtrate and a filter cake; wherein the filtrate is a mixed solution of potassium dihydrogen phosphate and inositol, and the filter cake is a mixture of magnesium hydrogen phosphate and calcium hydrogen phosphate;

[0070] S300, adding phytic acid hydrolyzate to the filtrate while stirring to adjust the pH value of the filtrate to 3.0, and separating the filtrate by simulated moving bed chromatography to obtain a potassium dihydrogen phosphate phase and an inositol phase; wherein the phytic acid hydrolyzate has a phosphoric acid content of 13.36wt%, an inositol content of 4.09wt%, and the rest are impurities;

[0071] S400, concentrating the potassium dihydrogen phosphate phase to a solid content of 55 wt% at a temperature of 80° C. and a stirring rate of 55 rpm, and cooling to 30° C. to precipitate potassium dihydrogen phosphate, filtering and drying the filter cake to obtain a potassium dihydrogen phosphate product free of calcium and magnesium ions.

[0072] The potassium dihydrogen phosphate product prepared in this example has a potassium dihydrogen phosphate content of 99 wt %, and neither calcium ions nor magnesium ions are detected.

[0073] Example 2

[0074] This embodiment provides a method for preparing potassium dihydrogen phosphate using potassium phytate, and simultaneously producing inositol, the method comprising the following steps:

[0075] S100, obtaining 2000 g of a potassium phytate solution; wherein the potassium phytate solution has a calcium ion content of 240 ppm and a magnesium ion content of 2500 ppm;

[0076] S200, adding KHCO3 to the potassium phytate solution while stirring to adjust the pH value of the potassium phytate solution to 7; then adding the potassium phytate solution to a hydrolysis kettle, and hydrolyzing it at a temperature of 180° C. and a pressure of 0.8 MPa for 8 hours to obtain a hydrolyzate of the potassium phytate solution; cooling the hydrolyzate to 65° C. and filtering to obtain a filtrate and a filter cake; wherein the filtrate is a mixed solution of potassium dihydrogen phosphate and inositol, and the filter cake is a mixture of magnesium hydrogen phosphate and calcium hydrogen phosphate;

[0077] S300, adding 1 wt% of activated carbon to the filtrate in step S200, stirring the filtrate at a temperature of 65° C. and a stirring rate of 20 rpm for 1 hour, filtering out the activated carbon to obtain a decolorized filtrate;

[0078] S400, obtaining a phytic acid solution with a mass concentration of 20wt%, adding the phytic acid solution into a hydrolysis kettle, and hydrolyzing for 8h at a temperature of 160°C and a pressure of 0.6Mpa to obtain a phytic acid hydrolyzate; wherein the phytic acid hydrolyzate has a phosphoric acid content of 17.82wt%, an inositol content of 5.45wt%, and the rest is impurities;

[0079] S500, adding the phytic acid hydrolyzate in step S400 to the decolorized filtrate in step S300 while stirring, adjusting the pH value of the filtrate to 3.8, and separating the filtrate by simulated moving bed chromatography to obtain a potassium dihydrogen phosphate phase and an inositol phase;

[0080] S600, concentrating the potassium dihydrogen phosphate phase in step S500 to a solid content of 60 wt % at a temperature of 80° C. and a stirring rate of 50 rpm, cooling to 40° C. to precipitate potassium dihydrogen phosphate, and filtering to obtain a first potassium dihydrogen phosphate filtrate and a first potassium dihydrogen phosphate filter cake; then concentrating the first potassium dihydrogen phosphate filtrate to a solid content of 60 wt % at a temperature of 80° C. and a stirring rate of 45 rpm, and cooling to 30° C. to precipitate potassium dihydrogen phosphate, and filtering to obtain a second potassium dihydrogen phosphate filtrate and a second potassium dihydrogen phosphate filter cake; mixing the first potassium dihydrogen phosphate filter cake and the second potassium dihydrogen phosphate filter cake and drying them at 105° C. to obtain a potassium dihydrogen phosphate product;

[0081] S700, concentrating the inositol phase in step S500 to dryness at a temperature of 80° C. and a stirring rate of 100 rpm to obtain an inositol product.

[0082] The potassium dihydrogen phosphate product prepared in this example has a potassium dihydrogen phosphate content of 99.1 wt%, and calcium ions and magnesium ions are not detected. The inositol content in the inositol product is 99.2 wt%.

[0083] Example 3

[0084] This embodiment provides a method for preparing potassium dihydrogen phosphate using potassium phytate, and simultaneously producing inositol, the method comprising the following steps:

[0085] S100, obtaining 2000 g of a potassium phytate solution; wherein the potassium phytate solution has a calcium ion content of 240 ppm and a magnesium ion content of 2400 ppm;

[0086] S200, adding K2CO3 to the potassium phytate solution while stirring to adjust the pH value of the potassium phytate solution to 5.5; then adding the potassium phytate solution to a hydrolysis kettle, and hydrolyzing it at a temperature of 160° C. and a pressure of 0.6 MPa for 8 hours to obtain a hydrolyzate of the potassium phytate solution; cooling the hydrolyzate to 50° C. and filtering to obtain a filtrate and a filter cake; wherein the filtrate is a mixed solution of potassium dihydrogen phosphate and inositol, and the filter cake is a mixture of magnesium hydrogen phosphate and calcium hydrogen phosphate;

[0087] S300, adding 5 wt% activated carbon to the filtrate of step S200, stirring the filtrate at a temperature of 45° C. and a stirring rate of 100 rpm for 0.5 h, filtering out the activated carbon to obtain a decolorized filtrate;

[0088] S400, obtaining a phytic acid solution with a mass concentration of 25wt%, adding the phytic acid solution to a hydrolysis kettle, and hydrolyzing for 6h at a temperature of 180°C and a pressure of 0.8Mpa to obtain a phytic acid hydrolyzate; wherein the phytic acid hydrolyzate has a phosphoric acid content of 22.27wt%, an inositol content of 6.18wt%, and the rest is impurities;

[0089] S500, adding the phytic acid hydrolyzate in step S400 to the decolorized filtrate in step S300 while stirring, adjusting the pH value of the filtrate to 3.5, and separating the filtrate by simulated moving bed chromatography to obtain a potassium dihydrogen phosphate phase and an inositol phase;

[0090] S600, concentrating the potassium dihydrogen phosphate phase in step S500 to a solid content of 65wt% at a temperature of 70°C and a stirring rate of 50rpm, cooling to 30°C to precipitate potassium dihydrogen phosphate, and filtering to obtain a first potassium dihydrogen phosphate filtrate and a first potassium dihydrogen phosphate filter cake; then concentrating the first potassium dihydrogen phosphate filtrate to a solid content of 60wt% at a temperature of 80°C and a stirring rate of 45rpm, cooling to 30°C to precipitate potassium dihydrogen phosphate, and filtering to obtain a second potassium dihydrogen phosphate filtrate and a second potassium dihydrogen phosphate filter cake; mixing the first potassium dihydrogen phosphate filter cake and the second potassium dihydrogen phosphate filter cake and drying them at 105°C to obtain a potassium dihydrogen phosphate product;

[0091] S700, concentrating the inositol phase in step S500 to dryness at a temperature of 70° C. and a stirring rate of 20 rpm to obtain an inositol product.

[0092] The potassium dihydrogen phosphate product prepared in this example has a potassium dihydrogen phosphate content of 99.2 wt %, and calcium ions and magnesium ions are not detected. The inositol content in the inositol product is 99.3 wt %.

[0093] Example 4

[0094] This embodiment provides a method for preparing potassium dihydrogen phosphate using potassium phytate, and simultaneously producing inositol, the method comprising the following steps:

[0095] S100, obtaining 2000 g of a potassium phytate solution; wherein the potassium phytate solution has a calcium ion content of 280 ppm and a magnesium ion content of 3000 ppm;

[0096] S200, adding KOH to the potassium phytate solution while stirring to adjust the pH value of the potassium phytate solution to 6; then adding the potassium phytate solution to a hydrolysis kettle, and hydrolyzing it at a temperature of 170° C. and a pressure of 0.7 MPa for 7 hours to obtain a hydrolyzate of the potassium phytate solution; cooling the hydrolyzate to 55° C. and filtering to obtain a filtrate and a filter cake; wherein the filtrate is a mixed solution of potassium dihydrogen phosphate and inositol, and the filter cake is a mixture of magnesium hydrogen phosphate and calcium hydrogen phosphate;

[0097] S300, adding 3 wt% of activated carbon to the filtrate of step S200, stirring the filtrate at a temperature of 50° C. and a stirring rate of 60 rpm for 0.8 h, filtering out the activated carbon to obtain the decolorized filtrate;

[0098] S400, obtaining a phytic acid solution with a mass concentration of 20wt%, adding the phytic acid solution into a hydrolysis kettle, and hydrolyzing for 8h at a temperature of 160°C and a pressure of 0.6Mpa to obtain a phytic acid hydrolyzate; wherein the phytic acid hydrolyzate has a phosphoric acid content of 17.82wt%, an inositol content of 5.45wt%, and the rest is impurities;

[0099] S500, adding the phytic acid hydrolyzate in step S400 to the decolorized filtrate in step S300 while stirring, adjusting the pH value of the filtrate to 3.5, and separating the filtrate by simulated moving bed chromatography to obtain a potassium dihydrogen phosphate phase and an inositol phase;

[0100] S600, concentrating the potassium dihydrogen phosphate phase in step S500 to a solid content of 65wt% at a temperature of 90°C and a stirring rate of 50rpm, cooling to 30°C to precipitate potassium dihydrogen phosphate, and filtering to obtain a first potassium dihydrogen phosphate filtrate and a first potassium dihydrogen phosphate filter cake; then concentrating the first potassium dihydrogen phosphate filtrate to a solid content of 65wt% at a temperature of 90°C and a stirring rate of 45rpm, cooling to 30°C to precipitate potassium dihydrogen phosphate, and filtering to obtain a second potassium dihydrogen phosphate filtrate and a second potassium dihydrogen phosphate filter cake; mixing the first potassium dihydrogen phosphate filter cake and the second potassium dihydrogen phosphate filter cake and drying at 105°C to obtain a potassium dihydrogen phosphate product;

[0101] S700, concentrating the inositol phase in step S500 to dryness at a temperature of 70° C. and a stirring rate of 20 rpm to obtain an inositol product.

[0102] The potassium dihydrogen phosphate product prepared in this example has a potassium dihydrogen phosphate content of 99 wt %, and calcium ions and magnesium ions are not detected. The inositol content in the inositol product is 99.2 wt %.

[0103] Comparative Example 1

[0104] The method for preparing potassium dihydrogen phosphate using potassium phytate provided in this comparative example is basically the same as that in Example 1, except that, in step S200, the potassium phytate solution is added to a hydrolysis kettle and hydrolyzed for 10 hours at a temperature of 160° C. and a pressure of 0.6 MPa to obtain a hydrolyzate of the potassium phytate solution, and then the hydrolyzate is directly filtered without a cooling process to obtain a filtrate and a filter cake.

[0105] The potassium dihydrogen phosphate product prepared in this comparative example has a potassium dihydrogen phosphate content of 92wt%, a calcium ion content of 122ppm, and a magnesium ion content of 624ppm.

[0106] It can be seen that the potassium dihydrogen phosphate content in the potassium dihydrogen phosphate product prepared under the conditions of this comparative example is lower than 99wt% of Example 1, and relative to Example 1, the potassium dihydrogen phosphate product of this comparative example contains calcium and magnesium ions, and the presence of calcium and magnesium ions reduces the quality of the potassium dihydrogen phosphate product of this comparative example. This is because the solubility of calcium hydrogen phosphate and magnesium hydrogen phosphate in the hydrolyzate of the potassium phytate solution is high under high temperature conditions, and only a small amount of calcium hydrogen phosphate and magnesium hydrogen phosphate are filtered and removed during the filtration process. The residual calcium and magnesium ions cannot be completely separated and removed during the concentration process of step S400, thereby reducing the quality of the potassium dihydrogen phosphate product of this comparative example.

[0107] Comparative Example 2

[0108] The method for preparing potassium dihydrogen phosphate using potassium phytate provided in this comparative example is basically the same as that in Example 1, except that in step S200, the pH value of the potassium phytate solution is adjusted to 4.0 by controlling the amount of KOH added.

[0109] The potassium dihydrogen phosphate product prepared in this comparative example has a potassium dihydrogen phosphate content of 90wt%, a calcium ion content of 62ppm, and a magnesium ion content of 795ppm;

[0110] It can be seen that the potassium dihydrogen phosphate content in the potassium dihydrogen phosphate product prepared under the conditions of this comparative example is lower than 99wt% of Example 1, and relative to Example 1, the potassium dihydrogen phosphate product of this comparative example contains calcium and magnesium ions, and the presence of calcium and magnesium ions reduces the quality of the potassium dihydrogen phosphate product of this comparative example. This is because when the pH value of the potassium phytate solution is lower than 5.0, only a small amount of calcium hydrogen phosphate and magnesium hydrogen phosphate are generated during the hydrolysis of the potassium phytate solution, resulting in excessively high residual calcium and magnesium ions in the filtrate, and they cannot be completely separated and removed during the concentration process of step S400, thereby reducing the quality of the potassium dihydrogen phosphate product of this comparative example.

[0111] Through the above embodiments, comparative examples, and test data, it can be known that under the conditions of the embodiments of the present invention, by controlling the pH value of the potassium phytate solution to 5-7, and by adding the phytic acid hydrolyzate to the filtrate to adjust the pH value of the filtrate to 3.0-3.8, the calcium and magnesium ions remaining in the filtrate can be dissolved in the potassium dihydrogen phosphate phase, and the potassium dihydrogen phosphate phase is concentrated to a solid content of 55-65wt%, and the residual calcium and magnesium ions can be separated into the potassium dihydrogen phosphate concentrate after filtration, and a potassium dihydrogen phosphate product free of calcium and magnesium ions is obtained. Through the technical solution of the present invention, the poor quality and low yield of the potassium dihydrogen phosphate prepared by potassium phytate in the prior art, as well as the technical problems of complex process.

[0112] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in a suitable manner in any one or more embodiments or examples.

[0113] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preparing potassium dihydrogen phosphate using potassium phytate, characterized in that: include: obtaining a potassium phytate solution containing calcium and magnesium ion impurities; The potassium phytate solution is hydrolyzed at a pH value of 5 to 7 to obtain a hydrolyzate, and the hydrolyzate is filtered at 50 to 65° C. to obtain a filtrate and a filter cake; wherein the filtrate is a mixed solution of potassium dihydrogen phosphate and inositol, and the filter cake is a mixture of magnesium hydrogen phosphate and calcium hydrogen phosphate; Adding phytic acid hydrolyzate to the filtrate to adjust the pH value to 3.0-3.8, and subjecting the filtrate to chromatographic separation to obtain a potassium dihydrogen phosphate phase and an inositol phase; The potassium dihydrogen phosphate phase is concentrated to a solid content of 55-65 wt %, filtered and the filter cake is dried to obtain a potassium dihydrogen phosphate product free of calcium and magnesium ions.

2. The method for preparing potassium dihydrogen phosphate using potassium phytate according to claim 1, characterized in that: The hydrolysis method includes high temperature and high pressure hydrolysis, phytase hydrolysis or microwave hydrolysis.

3. The method for preparing potassium dihydrogen phosphate using potassium phytate according to claim 1 or 2, characterized in that, The hydrolysis method adopts high temperature and high pressure hydrolysis, and the high temperature and high pressure hydrolysis process is: The potassium phytate solution is added into a hydrolysis kettle, and hydrolyzed for 6 to 10 hours at a temperature of 160 to 200°C and a pressure of 0.6 to 1 MPa to obtain the hydrolyzate.

4. The method for preparing potassium dihydrogen phosphate using potassium phytate according to claim 1, characterized in that: The step of concentrating the potassium dihydrogen phosphate phase to a solid content of 55 to 65 wt % comprises: The potassium dihydrogen phosphate phase is concentrated to a solid content of 55-65 wt %, and the temperature is lowered to 30-40° C. to precipitate the potassium dihydrogen phosphate, and filtered to obtain a first potassium dihydrogen phosphate filtrate and a first potassium dihydrogen phosphate filter cake; The first potassium dihydrogen phosphate filtrate is then concentrated to a solid content of 55-65 wt %, and the temperature is lowered to 30-40° C. to precipitate the potassium dihydrogen phosphate, and filtered to obtain a second potassium dihydrogen phosphate filtrate and a second potassium dihydrogen phosphate filter cake; The first potassium dihydrogen phosphate filter cake and the second potassium dihydrogen phosphate filter cake are mixed and then dried to obtain the potassium dihydrogen phosphate product.

5. The method for preparing potassium dihydrogen phosphate using potassium phytate according to claim 1, characterized in that: After the potassium phytate solution is hydrolyzed at a pH value of 5 to 7 to obtain a hydrolyzate, and the hydrolyzate is filtered at 55 to 65° C. to obtain a filtrate and a filter cake, before the phytic acid hydrolyzate is added to the filtrate, the method further comprises: Obtaining a phytic acid solution with a mass concentration of 15 to 25 wt%; The phytic acid solution is added into a hydrolysis kettle, and hydrolyzed for 6 to 10 hours at a temperature of 160 to 200° C. and a pressure of 0.6 to 1.0 MPa to obtain the phytic acid hydrolyzate.

6. The method for preparing potassium dihydrogen phosphate using potassium phytate according to claim 1, characterized in that: After obtaining the potassium phytate solution containing calcium and magnesium ion impurities, before hydrolyzing the potassium phytate solution at a pH value of 5 to 7 to obtain a hydrolyzate, the method further comprises: An alkaline substance is added to the potassium phytate solution to adjust the pH value of the potassium phytate solution to 5-7.

7. The method for preparing potassium dihydrogen phosphate using potassium phytate according to claim 6, characterized in that: The alkaline substance includes KOH, K2CO3 or KHCO3.

8. The method for preparing potassium dihydrogen phosphate using potassium phytate according to claim 1, characterized in that: After adding phytic acid hydrolyzate to the filtrate to adjust the pH value to 3.0-3.8, and before subjecting the filtrate to chromatographic separation, the method further comprises: 1-5 wt % of activated carbon is added to the filtrate, and the mixture is stirred for 0.5-1 h at a temperature of 45-65° C. and a stirring rate of 20-100 rpm. The activated carbon is filtered out to obtain a decolorized filtrate.

9. A potassium dihydrogen phosphate product, characterized in that: The method for preparing potassium dihydrogen phosphate using potassium phytate according to any one of claims 1 to 8 is used to prepare the potassium dihydrogen phosphate product, wherein the potassium dihydrogen phosphate content in the potassium dihydrogen phosphate product is 99.0 to 99.5 wt %, and the rest is impurities.

10. A method for preparing inositol, characterized in that: The method for preparing potassium dihydrogen phosphate using potassium phytate according to any one of claims 1 to 8, after obtaining the inositol phase, further comprises: The inositol phase is concentrated to dryness at a temperature of 70-100° C. and a stirring rate of 20-100 rpm to obtain an inositol product; wherein the inositol content in the inositol product is 99-99.8wt%, and the rest is impurities.

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