Lithium dihydrogen phosphate and production method for co-producing inositol by using lithium dihydrogen phosphate

Abstract

The invention discloses a production method of lithium dihydrogen phosphate and co-production of inositol thereof, and belongs to the technical field of chemical engineering, a plant-derived phytic acid solution is used as a raw material, after chloroethanol quaternization anion exchange resin is used for adsorption, desorption treatment and hydrolysis treatment are sequentially carried out, and continuous separation is carried out through a simulated moving full-chamber bed device; therefore, the production efficiency can be remarkably improved, the energy consumption of a unit product can be reduced, all-component conversion from phytate radicals to lithium dihydrogen phosphate and inositol can be realized, and finally battery-grade lithium dihydrogen phosphate (LiH2PO4) and food-medicine-grade inositol (C6H12O6) are obtained. The problems that in the prior art, preparation of battery-grade lithium dihydrogen phosphate highly depends on a high-purity lithium salt raw material, the preparation cost is high, production of inositol has large influence on the environment, and the utilization rate of the raw material is low are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the chemical technology field, and in particular to a production method of lithium dihydrogen phosphate and co-production of inositol. BACKGROUND

[0002] As an important raw material in the field of new energy lithium batteries, lithium dihydrogen phosphate is mainly used for preparing lithium iron phosphate positive electrode material. Under the background of rapid development of lithium ion battery industry, lithium dihydrogen phosphate can provide phosphorus source and lithium source at the same time. When lithium iron phosphate is synthesized with iron oxalate as the main raw material, the compaction density and energy density are superior to other process paths, and it has become the main process scheme and raw material of the third generation and fourth generation lithium iron phosphate. In addition, lithium dihydrogen phosphate can also be used for preparing electrolyte additives such as lithium manganese iron phosphate and lithium difluorophosphate.

[0003] Inositol is an important component of vitamin B family, and is widely used in medicine, food, cosmetics, feed and other fields. In the field of medicine, inositol can be used for treating diseases such as cirrhosis, fatty liver and diabetes, and can be used as an intermediate for synthesizing nicotinic acid inositol ester, inositol selenium acid ester and other drugs. In the feed industry, inositol can promote animal growth and improve feed utilization efficiency.

[0004] In the prior art, the preparation of battery-grade lithium dihydrogen phosphate highly depends on high-purity lithium salt raw materials, resulting in high preparation cost. The production of inositol has a greater impact on the environment, and the utilization rate of raw materials is low. Therefore, how to reduce the preparation cost of lithium dihydrogen phosphate, reduce the impact of inositol production on the environment, and improve the utilization rate of inositol production raw materials is a technical problem to be solved. SUMMARY

[0005] The main purpose of the present application is to provide a production method of lithium dihydrogen phosphate and co-production of inositol, which aims to solve the problems in the prior art that the preparation of battery-grade lithium dihydrogen phosphate highly depends on high-purity lithium salt raw materials, resulting in high preparation cost, and the production of inositol has a greater impact on the environment and the utilization rate of raw materials is low.

[0006] To achieve the above-mentioned purpose, the present application provides a production method of lithium dihydrogen phosphate and co-production of inositol, which comprises the following steps: adsorbing a phytic acid solution of plant source on a chloroethanol quaternary amine anion exchange resin to obtain an anion exchange resin adsorbed with phytate ions; injecting a mixed desorption solution containing lithium chloride and inorganic acid into the anion exchange resin adsorbed with phytate ions to perform desorption treatment, and obtaining a lithium phytate solution; performing hydrolysis treatment on the lithium phytate solution to obtain a mixed aqueous solution of lithium dihydrogen phosphate and inositol; The simulated moving full-bed device is used for continuously separating the mixed aqueous solution of lithium dihydrogen phosphate and inositol, and lithium dihydrogen phosphate solution and inositol solution are obtained respectively. The lithium dihydrogen phosphate solution and the inositol solution are purified, concentrated and crystallized in sequence, and lithium dihydrogen phosphate and inositol are obtained.

[0007] Alternatively, the preparation method of the chloroethanol quaternary amine anion exchange resin is as follows: The white ball resin is obtained by polymerization reaction of styrene-divinylbenzene and methyl acrylate, methyl methacrylate or ethyl acrylate. The chloromethylation catalytic reaction is performed on the white ball resin, and then the ammination and quaternary amination reactions are performed in sequence by using ethylenediamine and chloroethanol, so as to obtain the chloroethanol quaternary amine anion exchange resin.

[0008] Alternatively, the dosage of the mixed desorption solution is 2bv~4bv, and the injection flow rate is 0.5bv / h~1.5bv / h.

[0009] Alternatively, the concentration of the lithium chloride is 1mol / L~5mol / L, and the concentration of the inorganic acid is 0.5mol / L~2.0mol / L.

[0010] Alternatively, the temperature of the desorption treatment is 25℃~60℃.

[0011] Alternatively, the hydrolysis treatment is based on the following steps: After the membrane filtration of the lithium phytate solution, the solution is placed in a high-pressure reactor, heated to a preset temperature, and then incubated at a preset pressure for a preset time, and then cooled to room temperature, so as to complete the hydrolysis treatment.

[0012] Alternatively, in the above hydrolysis treatment, the preset temperature is 120℃~200℃, the preset pressure is 0.6MPa~0.8MPa, and the preset time is 2h~8h.

[0013] Alternatively, in the process of continuously separating the mixed aqueous solution of lithium dihydrogen phosphate and inositol by using the simulated moving full-bed device, the feeding flow rate is 1.5mL / min~2.5mL / min, the switching time is 4.5min~5.5min, and the continuous separation time is 3.5h~4.5h.

[0014] To achieve the above purpose, the application further provides a lithium dihydrogen phosphate prepared by the above production method.

[0015] Alternatively, the purity of the lithium dihydrogen phosphate is >99.9%, and the content of metal impurities is less than 10ppm.

[0016] Compared with the prior art, the beneficial effects that can be achieved by the present application are as follows: 1. In the technical solution of the present application, the phytic acid solution of plant origin is used as raw material, and after adsorption by chloroethanol quaternary amine anion exchange resin, desorption treatment and hydrolysis treatment are sequentially performed, and continuous separation is performed through a simulated moving full bed device. Not only can the production efficiency be significantly improved and the energy consumption per unit product be reduced, but also the full component conversion of phytate to lithium dihydrogen phosphate and inositol can be realized, and finally battery-grade lithium dihydrogen phosphate (LiH2PO4) and food-grade inositol (C6H 12 O6) are obtained, which has strong industrial adaptability and high economic value, and solves the problems in the prior art that the preparation of battery-grade lithium dihydrogen phosphate highly depends on high-purity lithium salt raw materials, the production cost is high, the production of inositol has a greater impact on the environment, and the raw material utilization rate is low.

[0017] 2. In the co-production process of lithium dihydrogen phosphate and inositol, the process conditions are mild, no greenhouse gases such as carbon dioxide are produced, and no pressure is exerted on the environment, which meets the requirements of green chemical development.

[0018] 3. The purity of lithium dihydrogen phosphate obtained by the production method of the present application is > 99.9%, and the content of metal impurities is less than 10 ppm, which is battery-grade lithium dihydrogen phosphate, and the purity of co-produced inositol is > 98.5%, which is suitable for medical or food grade applications. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is a flowchart of the production method for co-producing lithium dihydrogen phosphate and inositol. Figure 2 It is a resin column structure front view of a simulated moving full bed device.

[0020] BRIEF DESCRIPTION OF DRAWINGS: Figure 2 In the figure, 1 is a lower discharge port, 2 is a lower manhole, 3 is a resin column, 4 is an upper manhole, 5 is an upper feed port, 6 is an upper water distributor, 7 is an upper agent loading port, 8 is a lower agent discharge port, 9 is a fixed support, and 10 is a lower water distributor. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0022] In order to solve the problems in the prior art that the preparation of battery-grade lithium dihydrogen phosphate is highly dependent on high-purity lithium salt raw materials, resulting in high preparation cost, the production of inositol has a greater impact on the environment, and the utilization rate of raw materials is low, the present application provides a production method for co-producing lithium dihydrogen phosphate and inositol, as shown in Figure 1 The production method comprises the following steps: S10. Using chloroethanol quaternary amination anion exchange resin to adsorb phytic acid solution of plant source, to obtain anion exchange resin adsorbed with phytate ions; S20. Injecting mixed desorption solution containing lithium chloride and inorganic acid into the anion exchange resin adsorbed with phytate ions, to perform desorption treatment, to obtain lithium phytate solution; S30. Performing hydrolysis treatment on the lithium phytate solution, to obtain mixed aqueous solution of lithium dihydrogen phosphate and inositol; S40. Using a simulated moving full-bed device to continuously separate the mixed aqueous solution of lithium dihydrogen phosphate and inositol, to obtain lithium dihydrogen phosphate solution and inositol solution respectively; S50. Respectively performing purification, concentration and crystallization on the lithium dihydrogen phosphate solution and the inositol solution in sequence, to obtain lithium dihydrogen phosphate and inositol.

[0023] Optionally, in the phytic acid solution of plant source, the plant source can be selected from plant raw materials containing phytic acid.

[0024] Optionally, the plant raw material containing phytic acid can be corn leaching solution, rice bran leaching solution, or leaching solution mixed by corn leaching solution and rice bran leaching solution in any proportion.

[0025] Optionally, taking rice bran leaching solution as an example, the leaching method of the phytic acid solution of plant source can be as follows: commercially available rice bran powder is mixed with deionized water at a mass ratio of 1:10, and stirred and leached at 70°C for 2 hours; then 0.45 μm filter membrane is used for filtration, to obtain clear phytic acid solution, and the pH value of the phytic acid solution is about 4.5.

[0026] Optionally, the method for obtaining anion exchange resin adsorbed with phytate ions by using chloroethanol quaternary amination anion exchange resin to adsorb phytic acid solution of plant source can be as follows: Chloroethanol quaternary amination anion exchange resin is filled in a column, and the particle size of the resin is about 0.60±50 mm; then the clear phytic acid solution is injected into the resin column at a flow rate of 1 bv / h, until the resin is saturated, and the saturation state is marked by the fact that the phytic acid concentration in the effluent of the resin column outlet is less than 2%.

[0027] Optionally, after the adsorption is completed, the impurities in the anion exchange resin adsorbed with the phytate ions can be eluted with deionized water until the content of sodium, potassium and other impurity ions in the eluent is less than 5 ppm.

[0028] Optionally, the inorganic acid in the mixed desorption solution can be hydrochloric acid (HCl).

[0029] Optionally, the method of injecting the mixed desorption solution containing lithium chloride and inorganic acid into the anion exchange resin adsorbed with the phytate ions to perform desorption treatment to obtain a lithium phytate solution can be: The lithium chloride and the inorganic acid are mixed in a volume ratio of 1:1 to obtain a mixed desorption solution, which is injected into the anion exchange resin adsorbed with the phytate ions. When the content of lithium (Li) in the effluent at the outlet of the resin column reaches 0.5%, the desorption solution is collected, which is the lithium phytate solution, and the concentration of lithium salt is about 12%.

[0030] Optionally, in the continuous separation of the mixed aqueous solution of lithium dihydrogen phosphate and inositol by using the simulated moving full-bed device, the resin used can be a cation exchange resin or a macroporous adsorption resin, and the particle size of the resin can be 300 μm to 800 μm; and the mobile phase can be deionized water.

[0031] In the technical scheme of the present application, the front view of the single resin column structure of the simulated moving full-bed device can be as shown in Figure 2 The front view of the single resin column structure of the simulated moving full-bed device can be as shown in

[0032] Optionally, the separation system of the simulated moving full-bed device can be composed of six independent resin columns, which can be divided into four zones Z1 (1 column), Z2 (2 columns), Z3 (2 columns) and Z4 (1 column), to realize the functional division of the adsorption zone, the elution zone, the refining zone and the regeneration zone, and to achieve the purpose of continuous separation.

[0033] In the technical scheme of the present application, in the process of continuously separating the mixed aqueous solution of lithium dihydrogen phosphate and inositol by using the simulated moving full-bed device, the position of the material inlet and outlet can be periodically switched by the valve, so that the position of the material inlet and outlet moves relative to the resin column, thereby simulating the movement of the resin in the opposite direction to realize continuous separation. That is, the resin does not move, and the flow direction of the material can be changed by valve array switching, which can be equivalent to the movement of the resin.

[0034] Further, when the mixed aqueous solution of lithium dihydrogen phosphate and inositol is continuously separated by using the simulated moving full-bed device, the mixed aqueous solution is first immersed in the Z1 zone, Li +The inositol is quickly eluted with part of the mobile phase adsorbed by the resin; secondly, the mobile phase enters the Z2 zone, and the Li adsorbed by the resin can be eluted + , to obtain a high-concentration lithium dihydrogen phosphate solution; thirdly, a small amount of the mobile phase is used to flush the Z3 zone, so that the residual inositol in the resin layer is removed, and the lithium dihydrogen phosphate solution is further refined; finally, the Z4 zone is flushed with the mobile phase or the regeneration solution, and the regenerated resin column is switched to the Z1 zone through the valve array, so that the cycle is realized.

[0035] Further, when the above-mentioned mixed aqueous solution of lithium dihydrogen phosphate and inositol is continuously separated by using the simulated moving full-bed device, the valve opening and closing of the feed, the discharge, and the mobile phase inlet of each column can be controlled by programming, so that the periodic movement of the material flow is realized; every time the preset switching time is reached, the above-mentioned four zones are switched in turn, the resin is simulated to circulate from "adsorption - elution - refinement - regeneration - adsorption", and the feeding, separation, product recovery, and resin regeneration are synchronized, which breaks through the intermittent limitation of the traditional fixed bed "adsorption - stop - elution", and improves the separation efficiency.

[0036] Alternatively, the method for sequentially purifying, concentrating, and crystallizing the lithium dihydrogen phosphate solution and the inositol solution can be as follows: The lithium dihydrogen phosphate solution is sequentially treated by a nanofiltration membrane and a reverse osmosis membrane to remove multivalent metal ions and part of organic small molecules, and the solution concentration is increased to 1.2 mol / L, so that the total content of impurity ions is less than 5 ppm; then, the solution is evaporated, concentrated, and crystallized under vacuum at 60°C, the crystals are collected and dried for 12 h, and finally, a battery-grade lithium dihydrogen phosphate product with a purity of > 99.9% and a metal impurity content of less than 10 ppm is obtained; The inositol solution is subjected to activated carbon adsorption decolorization, and the pH value is adjusted to 7.0; pre-cooled ethanol is added in a volume ratio of 1:2 for precipitation, and the mixture is placed at 0°C for 2 h, then filtered, washed, and dried, so that a crystalline inositol with a purity of > 98.5% is obtained, which is suitable for pharmaceutical or food grade applications.

[0037] In a possible implementation method, the preparation method of the chloroethanol quaternary amine anion exchange resin is as follows: The white ball resin is obtained by polymerization reaction of styrene-divinylbenzene and methyl acrylate, methyl methacrylate, or ethyl acrylate; The white ball resin is subjected to chloromethylation catalytic reaction, and then amine reaction and quaternary amine reaction are sequentially performed by using ethylenediamine and chloroethanol, to obtain the chloroethanol quaternary amine anion exchange resin.

[0038] Optionally, the mass ratio of the styrene-divinyl benzene monomers described above is 90-93:7-10, wherein styrene is the main monomer and divinyl benzene is the crosslinking agent. When the mass ratio of styrene to divinyl benzene is 90-93:7-10, the performance of the obtained styrene-divinyl benzene copolymer can be ensured to be dominated by styrene, and the copolymer skeleton is prevented from being too brittle due to too high divinyl benzene content.

[0039] Optionally, the mass ratio of the styrene-divinyl benzene to methyl acrylate, methyl methacrylate or ethyl acrylate described above can be 10-20:100.

[0040] Optionally, when the styrene-divinyl benzene and methyl acrylate, methyl methacrylate or ethyl acrylate described above are subjected to a copolymerization reaction, the implementation can be as follows: reaction at a temperature of 75-85℃ for 6-8h, then temperature is raised to 90-95℃, and reaction is continued for 2-4h, and finally white ball resin is obtained.

[0041] It should be noted that, in the preparation process of the white ball resin described above, in the first stage, if the temperature is higher than 85℃, the reactant material will be rapidly decomposed, the free radical concentration will be suddenly increased, and the polymerization exothermic will be instantaneously generated, which is easy to cause the problem of "explosion polymerization". The temperature range of 75-85℃ is matched with the reaction monomers, and the free radicals can be slowly released within 6-8h, so that the polymerization reaction can be uniformly carried out, and the resin particles are prevented from having bubbles, cavities or surface charring. After the first stage is completed, the monomer concentration in the system is reduced, and the reaction rate is slowed down, and especially the divinyl benzene and the ester monomers which are not completely reacted are easily left. At this time, the temperature is raised to 90-95℃, which can increase the diffusion rate of free radicals, activate the un-decomposed initiators in the system, and make the residual monomers participate in the reaction, and at the same time, the influence of the residual monomers on the subsequent chloromethylation and amination steps is avoided.

[0042] Optionally, the temperature of the reaction of amination and quaternary amination by using ethylenediamine and chloroethanol in sequence described above can be 70-80℃, and the reaction time can be 2-3h.

[0043] Optionally, in the chloromethylation catalytic reaction described above, the catalyst can be ZnCl2, and when ZnCl2 is used as the catalyst, -CH2Cl active groups can be introduced.

[0044] Optionally, in the chloromethylation catalytic reaction described above, the reaction temperature can be 65-75℃, and the reaction time can be 5-6h. If the reaction temperature is lower than 65℃, the catalytic activity will be insufficient, the chloromethylation efficiency will be low, and the reaction period will be long. If the temperature is higher than 75℃, the thermal degradation of the acrylic ester segment in the resin will be caused, and the skeleton structure will be damaged. Within the range of 65-75℃, the catalytic activity requirement of ZnCl2 can be met, and the reaction efficiency and the skeleton stability can be taken into account.

[0045] It should be noted that in the above process of preparing chloroethanol quaternary amination ion exchange resin, there is a synergistic effect between the optional parameters of each step, which is specifically manifested in that: the monomer ratio of styrene to divinylbenzene can ensure the low and medium crosslinking degree, in the copolymerization process, the slow polymerization in the low temperature stage of 75-85℃ can form uniform initial pores, and the high temperature stage of 90-95℃ can promote the crosslinking of residual divinylbenzene to stabilize the pore structure. The reaction parameters under ZnCl2 catalysis and the backbone structure in the copolymerization stage can form a precise match, which can efficiently introduce the chloromethyl (-CH2Cl) active site without destroying the ester group and the pore. The parameters of ethylenediamine amination and chloroethanol quaternization can be coordinated with the active site density and pore structure formed by chloromethylation, so that the specific adsorption capacity of the final resin to phytate is enhanced.

[0046] It should be noted that in the process of preparing chloroethanol quaternary amination ion exchange resin by the above method, styrene-divinylbenzene is the crosslinked backbone of the ion exchange resin, and the amount of divinylbenzene as the crosslinking agent can control the crosslinking degree of the resin to be 8%-10%. Within this crosslinking degree range, the resin will neither be easily broken due to too low crosslinking degree, nor have too high mass transfer resistance due to too high crosslinking degree. Secondly, in this crosslinking system, the introduction of methyl acrylate, methyl methacrylate or ethyl acrylate can further optimize the toughness of the crosslinked backbone, reduce the volume shrinkage or expansion of the resin in the "adsorption-desorption" cycle, so that the swelling degree is less than 15%, thereby prolonging the service life of the resin.

[0047] Further, the acrylate monomers will be partially hydrolyzed or removed in the polymerization reaction, forming a mesopore-macropore mixed pore structure; and phytate is myo-inositol hexakisphosphate (C6H6O 24 P6 6- , which is a macromolecular anion, and the mesopore-macropore structure of the resin can allow phytate to rapidly diffuse to the functional group site, with an adsorption rate increase of more than 60% and a higher saturated adsorption capacity.

[0048] Further, in the above preparation method, through the three-step reaction of "chloromethylation→ ethylenediamine amination→ chloroethanol quaternization", chloroethanol quaternary ammonium groups (-N + (CH2CH2OH)3Cl - ) can be introduced. The structural characteristics of this group make it have high selectivity and strong binding force for the adsorption of phytate. Specifically, the quaternary ammonium group is a strong alkaline anion exchange group with high positive charge density, which can be combined with the six negative charges (C6H6O 24 P6 6-) form multiple point electrostatic binding, compared with weak basic anion resin (such as primary amine, secondary amine group), the strong basic resin can still maintain strong positive charge under acidic conditions, and will not cause the adsorption capacity to decrease due to acid protonation, and can stably adsorb phytate; and the weak base resin is easy to be protonated in the acidic environment, and the adsorption capacity for anions is significantly weakened; secondly, the chloroethanol chain (-CH2CH2OH) on the quaternary ammonium group has a hydroxyl group (-OH), and the group can form a hydrogen bond with the hydroxyl group in the phytate molecule; the "electrostatic binding + hydrogen bond synergistic" action mode makes the adsorption selectivity of the resin to phytate far higher than that of other small molecule anions; in addition, in the plant source phytate solution, a small amount of Cl - , PO4 3- , the resin can preferentially adsorb phytate, reduce the interference of impurity anions, and the purity of the obtained lithium phytate solution is higher.

[0049] Further, when ZnCl2 is selected as the catalyst, -CH2Cl active groups can be efficiently introduced on the benzene ring of the styrene-divinylbenzene skeleton, which can ensure the stability of the exchange capacity of the resin and avoid the instability of the phytate adsorption efficiency caused by the fluctuation of the exchange capacity.

[0050] Further, in the above preparation method, after the chloromethylation catalytic reaction, amination is first carried out by using ethylenediamine, then the amino group (-NH2) of the ethylenediamine can react with -CH2Cl to introduce a secondary amine or tertiary amine group (-N (CH2CH2NH2)-) on the crosslinked skeleton, thereby providing a reaction site for subsequent quaternary amination; then quaternary amination is carried out by using chloroethanol, and the -Cl of the chloroethanol can react with the nitrogen atom on the amine group to form a quaternary ammonium salt (-N + (CH2CH2OH)3Cl - ), and this step does not generate small molecule by-products, and the amount of chloroethanol used can be controlled to avoid the generation of tertiary amine residues.

[0051] Therefore, in the technical scheme of the present application, when a mixed desorption solution containing lithium chloride and inorganic acid is used to desorb the anion exchange resin adsorbed with phytate ions, Li + can compete with the positive charge of the quaternary ammonium group for the binding site, thereby destroying the electrostatic interaction; H + provided by the inorganic acid, such as hydrochloric acid, can bind with the hydroxyl group of phytate, thereby destroying the hydrogen bond interaction; through the synergistic effect of "reversible electrostatic + hydrogen bond binding", the desorption rate of phytate can reach more than 98%, and the resin after desorption can restore the positive charge state of the quaternary ammonium group through water washing, thereby significantly improving the recycling times and reducing the production cost. In addition, the chloroethanol quaternary amination anion exchange resin of the present application contains strong basic quaternary ammonium groups (-N +R3) will not be protonated under acidic conditions, while the weakly basic amine group will be protonated and deactivated, still maintaining a positive charge, and normal adsorption of phytate; compared with weakly basic anion resin, the resin does not need to adjust the pH value of the raw material liquid, and can be directly fed and adsorbed, simplifying the process steps; and the cross-linked structure of the resin skeleton contained therein is stable and will not swell excessively in a high-concentration salt solution, which can avoid the compaction of the resin and the increase of column pressure due to swelling; at the same time, the binding force between the quaternary ammonium group and Cl - is weaker than that between the quaternary ammonium group and phytate, and a high concentration of Cl - will not cause the resin to be deactivated prematurely.

[0052] In a possible implementation, the amount of the mixed desorption solution is 2bv~4bv, and the injection flow rate is 0.5bv / h~1.5bv / h.

[0053] It should be noted that when the amount of the mixed desorption solution is 2bv~4bv, the total amount of phytate adsorbed by the resin + the excess driving force can be covered, which can ensure that more than 95% of the phytate in the resin is eluted, further improve the desorption rate to more than 98%, and avoid the use of too much desorption solution, which leads to too low concentration of phytate in the desorption solution and increases the energy consumption of subsequent concentration.

[0054] Further, when the injection flow rate is 0.5bv / h~1.5bv / h, Li + (competitive electrostatic sites) in the desorption solution and H + (breaking hydrogen bonds) can fully act, if the flow rate is lower than 0.5bv / h, the treatment efficiency will be reduced; if the flow rate is higher than 1.5bv / h, the contact time is too short, the desorption solution and the resin do not fully contact, and part of the phytate is not fully eluted and flows out with the desorption solution, which will lead to fluctuations in the concentration of phytate in the desorption solution and increase the residual phytate in the resin.

[0055] In a possible implementation, the concentration of lithium chloride is 1mol / L~5mol / L, and the concentration of the inorganic acid is 0.5mol / L~2mol / L.

[0056] It should be noted that when the concentration of lithium chloride is 1mol / L~5mol / L, during the desorption treatment, a high concentration of Li + can compete with phytate for the positive charge sites of the quaternary ammonium group on the resin; and Li + has a small radius and high charge density, which can effectively replace phytate and combine with the quaternary ammonium group, thereby destroying the electrostatic binding force between phytate and the resin, and making phytate fall off from the resin into the desorption solution; when the concentration of the inorganic acid is 0.5mol / L~2mol / L, H +It can bind to the hydroxyl groups in phytate molecules, interfering with the hydrogen bonding between phytate and resin, and causing phytate to desorb from the resin.

[0057] Furthermore, lithium chloride can synergistically interact with inorganic acids through concentration to achieve a phytate desorption rate of over 98%; if the lithium chloride concentration is below 1 mol / L, then Li + Insufficient competitiveness; if it is higher than 5 mol / L, it will increase the cost of the desorption solution and the difficulty of subsequent treatment; if the inorganic acid concentration is lower than 0.5 mol / L, its ability to destroy hydrogen bonds is limited; if it is higher than 2 mol / L, it may cause some damage to the resin structure, while increasing the burden of subsequent treatments such as neutralization.

[0058] In one possible implementation, the temperature of the above desorption process is 25°C to 60°C.

[0059] It should be noted that in the above desorption treatment, when the desorption temperature is between 25℃ and 60℃, the desorption time can be shortened and the desorption rate increased by improving molecular motion efficiency and enhancing the interaction between the desorption solution and phytate. Specifically, within this temperature range, Li... + The diffusion coefficient is significantly improved, thereby accelerating H + The reaction rate with hydroxyl groups is increased, shortening the desorption time and stabilizing the desorption rate at over 95%. If the temperature is too high, such as above 60℃, it will lead to accelerated volatilization of the eluent and may trigger phytate hydrolysis, thus reducing the purity of the eluent; if the temperature is below 25℃, molecular motion is slow, and Li... + The diffusion rate within the resin channels is low, H + It has insufficient reactivity with the hydroxyl groups of phytate.

[0060] In one possible implementation, the above hydrolysis treatment is carried out based on the following steps: After membrane filtration, the lithium phytate solution is placed in a high-pressure reactor, heated to a preset temperature, held at a preset pressure for a preset time, and then cooled to room temperature to complete the hydrolysis process.

[0061] Optionally, the high-pressure reactor described above can be a high-pressure reaction vessel.

[0062] Optionally, the above membrane filtration can be performed by first using a ceramic membrane with a pore size of 0.45μm to 0.5μm, and then by using a nanofiltration membrane with a molecular weight cutoff of 1000D for concentration.

[0063] In one possible implementation, during the above-mentioned hydrolysis process, the preset temperature is 120℃~200℃, the preset pressure is 0.6MPa~0.8MPa, and the preset duration is 2h~8h.

[0064] It should be noted that the above-mentioned preset pressure is the autogenous pressure in the high-pressure reactor during the hydrolysis process, that is, as the reaction temperature increases and the reaction time extends, the pressure in the reactor gradually increases, and finally can be maintained at 0.6 MPa ~ 0.8 MPa.

[0065] It should be noted that in the above hydrolysis process, the concentration of the lithium phytate solution can be improved by membrane filtration, and the efficiency of the hydrolysis reaction can be enhanced. During the hydrolysis reaction in the high-pressure reactor, the conversion of "lithium phytate → lithium dihydrogen phosphate + inositol" occurs; in the phytate molecular structure, the phosphate group is connected to the inositol skeleton through a "C-O-P" bond, which has a high bond energy. When the temperature is 120℃ ~ 200℃, it can provide enough energy to break the C-O-P bond, so that each phytate molecule is completely hydrolyzed into 6 lithium dihydrogen phosphate molecules (LiH2PO4) and 1 inositol molecule (C6H 12 O6), without partial hydrolysis product residues. Secondly, when the preset pressure is 0.6 MPa ~ 0.8 MPa, the solution can be prevented from boiling violently at high temperature, ensuring that the reaction is carried out in a homogeneous liquid environment, reducing the local concentration caused by boiling. In the preset time range of 2h ~ 8h, high hydrolysis conversion rate can be achieved for high-concentration lithium phytate at 200℃ high temperature, meeting the demand for efficient production, while for lower concentration lithium phytate at 120℃, complete hydrolysis is ensured, and inositol degradation caused by too long reaction time is avoided.

[0066] In the above hydrolysis process, through the synergistic effect of each step, efficient conversion of "lithium phytate → mixed hydrolysis solution" can be achieved.

[0067] In one possible implementation, in the above process of continuously separating the mixed aqueous solution of lithium dihydrogen phosphate and inositol using the simulated moving full-bed device, the feed flow rate is 1.5 mL / min ~ 2.5 mL / min, the switching time is 4.5 min ~ 5.5 min, and the continuous separation time is 3.5h ~ 4.5h.

[0068] It should be noted that the above-mentioned switching time refers to the time interval for periodically switching the connection relationship of "feed port, mobile phase inlet, product sampling outlet, waste liquid discharge outlet" of each resin column in the simulated moving full-bed device (SMB) system according to the preset program.

[0069] Optionally, in the above process of continuously separating the mixed aqueous solution of lithium dihydrogen phosphate and inositol using the simulated moving full-bed device, the resin can be selected as a cation exchange resin as the stationary phase, and deionized water as the mobile phase, and the system partition is ≥ 4.

[0070] It should be noted that when the SMB is used for continuous separation of the mixed aqueous solution of lithium dihydrogen phosphate and inositol, compared with the traditional fixed bed chromatography, the SMB system is synchronized with the feeding and product production, and when the continuous separation time is 3.5h-4.5h, the Li+ recovery rate is ≥98%, and the inositol recovery rate is ≥95%, which is much higher than that of the traditional extraction process; secondly, when the feeding flow rate is 1.5mL / min-2.5mL / min, different total amounts of mixed solution can be adapted without replacing the resin column or adjusting the distribution of the functional area, thereby reducing the operation difficulty.

[0071] In order to achieve the above-mentioned purpose, the application further provides a lithium dihydrogen phosphate prepared by the above production method.

[0072] Optionally, the purity of the above-mentioned lithium dihydrogen phosphate is >99.9%, and the content of metal impurities is less than 10ppm, which is a battery-grade lithium dihydrogen phosphate.

[0073] By the production method of lithium dihydrogen phosphate and inositol provided by the application, the obtained lithium dihydrogen phosphate completely meets the "high-end power battery" index requirements in "Battery-grade lithium dihydrogen phosphate" (YS / T 1563.1-2022). The purity of the inositol produced by coproduction is >98.5%, which meets the "superior product" standard of "Food additives-inositol" (GB 1886.237-2016).

[0074] In the technical scheme of the application, the separation of lithium dihydrogen phosphate and inositol is completed simultaneously relying on the SMB system, and the subsequent purification is respectively carried out by "membrane separation-crystallization" and "adsorption-precipitation", which are both based on aqueous solution system, without switching solvents to reduce material transfer loss, and the ethanol waste liquid produced by inositol purification can be used for washing the crystals after lithium dihydrogen phosphate crystallization, realizing "waste resource", reducing the material consumption of the whole process. The production of lithium dihydrogen phosphate and inositol is coordinated, the resources are recycled, and the cost is optimized, realizing the "waste to treasure" of agricultural waste, and promoting the integrated development of circular economy and green manufacturing.

[0075] Example 1 A production method of lithium dihydrogen phosphate and inositol, comprising the following steps: S10. Based on S101 and S102, specifically as follows: S101. Mix the commercially available rice bran powder with deionized water at a mass ratio of 1:10, stir and extract at 70℃ for 2h, after the extraction is completed, filter with a 0.45μm filter membrane to obtain a clear phytic acid solution with a pH of about 4.5; S102. The white ball resin is obtained by mixing styrene-divinylbenzene with methyl acrylate at a mass ratio of 10-100, reacting at 75°C for 8h, then increasing the temperature to 90°C and continuing to react for 4h; the white ball resin is subjected to chloromethylation catalytic reaction with ZnCl2 at 65°C for 6h, and then subjected to amination and quaternary amination reaction with ethylenediamine and chloroethanol at 70°C in sequence for 3h to obtain a chloroethanol quaternary amine anion exchange resin; the chloroethanol quaternary amine anion exchange resin is packed in a column, and the phytic acid solution obtained in S10 is injected into the column at a flow rate of 1.0 bv / h until the resin is saturated, which is indicated by the phytic acid concentration in the effluent from the outlet of the resin column being less than 2%; after the adsorption is completed, the impurities in the resin are eluted with deionized water until the content of sodium, potassium and other impurity ions in the eluate is less than 5 ppm, and an anion exchange resin adsorbed with phytate ions is obtained.

[0076] S20. A mixed desorption solution is obtained by mixing 1.5 mol / L lithium chloride (LiCl) solution and 1.0 mol / L hydrochloric acid (HCl) solution at a volume ratio of 1:1, and then the mixed desorption solution is injected into the anion exchange resin adsorbed with phytate ions obtained in S20 at a flow rate of 1.0 BV / h at 40°C, and the amount of the mixed desorption solution is 3bv; when the lithium content in the outlet of the resin column reaches 0.5%, the desorption solution, i.e. lithium phytate solution, is collected, and the concentration thereof is about 12.0%.

[0077] S30. The lithium phytate solution obtained in S20 is subjected to ceramic membrane filtration with a pore size of 0.45-0.5μm to remove the suspended matter, and then concentrated by using a nanofiltration membrane with a molecular weight cut-off of 1000D, so that the concentration of the lithium phytate solution can reach 35%; the concentrated lithium phytate solution is placed in a high-pressure reaction kettle, heated to 160°C, and kept at a pressure of 0.8 MPa for 2h; after the reaction is completed, the solution is cooled to room temperature, and a small amount of precipitate is removed by filtration to obtain a mixed hydrolysate containing lithium dihydrogen phosphate and inositol.

[0078] S40. A four-zone simulated moving bed is set up with cation exchange resin as the stationary phase and deionized water as the mobile phase. The four zones are Z1 (1 column), Z2 (2 columns), Z3 (2 columns), and Z4 (1 column). The six resin columns in the four zones are 100% filled with cation exchange resin. The sealing of all pipelines and solenoid valve interfaces is checked. Then the mobile phase pump is turned on to flush the system and remove air bubbles from the resin columns and pipelines. The system is set to a feed flow rate of 2.0 mL / min. The mixed hydrolysate of lithium dihydrogen phosphate and inositol obtained in S30 is injected, and periodic switching is performed by the solenoid valve array to make the six columns circulate through the functional zones in the order of "Z1→Z2→Z3→Z4→Z1" with a switching time of 5 min. After continuous separation for 4.0 h, lithium dihydrogen phosphate solution and inositol solution are obtained, respectively. The purity of the lithium dihydrogen phosphate solution is ≥99.5%, the lithium concentration is about 0.75 mol / L, the purity of the inositol solution is ≥98%, and the concentration is about 0.05 mol / L.

[0079] S50. Based on S501~S502, the implementation is as follows: S501. The lithium dihydrogen phosphate solution obtained in S40 is treated by nanofiltration membrane and reverse osmosis membrane in sequence. The nanofiltration membrane can remove multivalent metal ions and part of small organic molecules, and the reverse osmosis membrane is used to concentrate the lithium dihydrogen phosphate solution. After treatment, the concentration of lithium dihydrogen phosphate is increased to 1.2 mol / L, and the total content of impurity ions is less than 5 ppm. S501. The lithium dihydrogen phosphate solution obtained in S501 is evaporated, concentrated and crystallized at 60°C under vacuum conditions. The crystals are collected and dried for 12 h to obtain a battery-grade lithium dihydrogen phosphate product with a purity of not less than 99.9% and a metal impurity content of less than 10 ppm. S503. The inositol solution obtained in S501 is subjected to activated carbon adsorption decolorization, the pH is adjusted to 7.0, pre-cooled ethanol is added in a volume ratio of 1:2 for precipitation, and the mixture is filtered after standing at 0°C for 2 h, washed and dried to obtain inositol crystals with a purity of about 98.5%, which are suitable for pharmaceutical or food grade applications.

[0080] In Example 1, set up Comparative Example 1 Comparative Example 1 differs from Example 1 in that in S10, a styrene-based anion exchange resin is used instead of a chloroethanol quaternary amine anion exchange resin to adsorb the phytic acid solution from plant sources. The remaining steps are the same as those of Example 1.

[0081] In Example 1, set up Comparative Example 2 Comparative Example 2 differs from Example 1 in that in S10, an acrylic acid-based anion exchange resin is used instead of a chloroethanol quaternary amine anion exchange resin to adsorb the phytic acid solution from plant sources. The remaining steps are the same as those of Example 1.

[0082] The adsorption capacity, adsorption rate of the anion exchange resin, the concentration of the lithium phytate solution, the purity and yield of lithium dihydrogen phosphate and inositol in Example 1, Comparative Example 2 and Comparative Example 2, respectively, were measured, and the results are shown in Table 1.

[0083] Table 1 By analyzing and comparing the data in Table 1, it can be seen that, first, in terms of the adsorption capacity and adsorption rate of the anion exchange resin for the phytic acid solution from plant sources, Example 1 is significantly better than Comparative Examples 1 and 2, because the chloroethanol quaternary amine anion exchange resin used in Example 1 can combine phytate through both electrostatic attraction + hydrogen bonding, and the macroporous structure of the resin allows free diffusion of phytate, with high utilization of the inner surface, so the adsorption capacity and efficiency are optimal; while the functional group of the styrene resin used in Comparative Example 1 is trimethylamine quaternary ammonium group (-N + (CH3)3), which only relies on single electrostatic attraction, and the hydrophobic effect of the methyl group repels the hydrophilic group of phytate, weakening the binding force; and its small pore structure and rigid benzene ring skeleton result in large steric hindrance, making it difficult for phytate to enter the pore, and only adsorbing on the surface, so the capacity and efficiency are significantly reduced. The functional group of the acrylic resin in Comparative Example 2 is mainly dimethylamine group (-N+(CH3)2H), with lower charge density and weaker electrostatic interaction with phytate; and its gel structure cannot accommodate large phytate molecules, and can only be adsorbed by a small amount of groups on the surface, so its performance is the worst.

[0084] Secondly, in terms of the concentration of the lithium phytate solution obtained by S20, because of the reduced adsorption capacity and adsorption rate of the anion exchange resin in Comparative Examples 1 and 2, the lithium phytate solution obtained after desorption treatment will be significantly reduced, which in turn will result in a significant decrease in the content of lithium dihydrogen phosphate and inositol in the mixed aqueous solution obtained after subsequent hydrolysis treatment. In contrast, the concentration of the lithium phytate solution obtained in Example 1 can be maintained at a relatively high value, which has a positive effect on subsequent processing, significantly increasing the content of lithium dihydrogen phosphate and inositol.

[0085] In addition, the styrene and acrylic anion exchange resins used in Comparative Examples 1 and 2 have poor selectivity for small molecular impurities in terms of the purity of lithium dihydrogen phosphate and inositol, which can cause impurity ions to enter the solution with the phytate after desorption treatment, the total content of impurities still exceeds the standard, and the final lithium dihydrogen phosphate product cannot meet the purity requirements of battery grade; and the ethylene and acrylic anion exchange resins have weak adsorption capacity for plant-derived pigments, which can cause the color of the inositol solution to deepen, which is lower than the required standard; at the same time, the acrylic resin has insufficient interception of sugar impurities, which can cause the purity of the final inositol product to decrease, which does not meet the application requirements of food and drug grade. In terms of yield, the double decline of the adsorption rate and the hydrolysis conversion rate of Comparative Examples 1 and 2 superimposes the loss of concentration, which can cause the yield of lithium dihydrogen phosphate and inositol to decrease and the production cost to increase. Compared with this, the purity and yield of lithium dihydrogen phosphate and inositol obtained in Example 1 are both higher, which meet the required standard.

[0086] According to the analysis of Table 1, in the technical scheme of the present application, the dual action force (electrostatic + hydrogen bond) and macroporous structure adaptability of the chloroethanol quaternary amine anion exchange resin are excellent in phytate adsorption performance, and have a synergistic effect with the subsequent process, which is the core material to ensure the efficient operation of the co-production process and cannot be replaced.

[0087] Example 2 A production method of lithium dihydrogen phosphate co-produced with inositol, comprising the following steps: S101 in S10 is the same as that in Example 1; S102. The white ball resin is obtained by mixing styrene-divinylbenzene and methyl methacrylate at a mass ratio of 20-100, reacting at 85°C for 6h, then increasing the temperature to 95°C and continuing to react for 2h; the white ball resin is subjected to chloromethylation catalytic reaction with ZnCl2 at 75°C for 5h, and then subjected to amine and quaternary amine reactions with ethylenediamine and chloroethanol at 80°C, respectively, for 2h to obtain the chloroethanol quaternary amine anion exchange resin; the chloroethanol quaternary amine anion exchange resin is packed in a column, and then the phytate solution obtained in S10 is injected into the column at a flow rate of 1.0 bv / h until the resin is saturated, which is marked by the phytate concentration in the outlet effluent of the resin column being less than 2%; after the adsorption is completed, the impurities in the resin are eluted with deionized water until the content of sodium, potassium and other impurity ions in the eluate is less than 5 ppm, to obtain the anion exchange resin adsorbed with phytate ions.

[0088] S20. A 1.0 mol / L lithium chloride (LiCl) solution is mixed with a 0.5 mol / L hydrochloric acid (HCl) solution at a volume ratio of 1:1 to obtain a mixed desorption solution. Then, the mixed desorption solution is injected into the anion exchange resin in S20, which has adsorbed phytate ions, at a flow rate of 0.5 BV / h at 60°C, and the amount is 4 BV. When the lithium content at the outlet of the resin column reaches 0.5%, the desorption solution, i.e., lithium phytate solution, is collected, and the concentration is about 12.0%.

[0089] S30. The lithium phytate solution obtained in S20 is passed through a ceramic membrane with a pore size of 0.45-0.5 μm to remove suspended matter, and then concentrated using a nanofiltration membrane with a molecular weight cutoff of 1000 D. The concentration of potassium phytate can reach 35%. Then, the concentrated lithium phytate solution is placed in a high-pressure reaction kettle, heated to 120°C, and maintained at a pressure of 0.6 MPa for 8 h. After the reaction is completed, the system is cooled to room temperature, and a small amount of precipitate is removed by filtration to obtain a mixed hydrolysate containing lithium dihydrogen phosphate and inositol.

[0090] S40. A four-zone simulated moving bed apparatus is set up using cation exchange resin as the stationary phase and deionized water as the mobile phase. The four zones are Z1 (1 column), Z2 (2 columns), Z3 (2 columns), and Z4 (1 column). The six resin columns in the four zones are 100% filled with cation exchange resin, and the sealing of all pipelines and solenoid valve interfaces is checked. Then, the mobile phase pump is started, and the system is flushed to remove air bubbles in the resin columns and pipelines. The system is set to a feed flow rate of 2.5 mL / min, and the mixed hydrolysate containing lithium dihydrogen phosphate and inositol obtained in S30 is injected. Periodic switching is performed by the solenoid valve array to make the six columns circulate through the functional zones in the order of "Z1→Z2→Z3→Z4→Z1" with a switching time of 4.5 min. After continuous separation for 4.5 h, lithium dihydrogen phosphate solution and inositol solution are obtained, respectively. The purity of the lithium dihydrogen phosphate solution is ≥99.5%, and the lithium concentration is about 0.75 mol / L. The purity of the inositol solution is ≥98%, and the concentration is about 0.05 mol / L.

[0091] S50 is the same as in Example 1.

[0092] Through S10-S50, a battery-grade lithium dihydrogen phosphate product with a purity of not less than 99.9% and a metal impurity content of less than 10 ppm is obtained. At the same time, an inositol crystal with a purity of about 98.5% is obtained, which is suitable for pharmaceutical or food grade applications.

[0093] In Example 2, Comparative Example 3 is set up. Comparative Example 3 differs from Example 2 in that, in S40, a fixed bed chromatographic column is used to separate the mixed aqueous solution of lithium dihydrogen phosphate and inositol. The rest is the same as in Example 2.

[0094] The technical solutions of Example 2 and Comparative Example 3 are analyzed from the aspects of concentration, purity and resin utilization rate of the product.

[0095] Specifically, first, in terms of separation of the mixed aqueous solution of lithium dihydrogen phosphate and inositol, the SMB device of Example 2 realizes continuous separation by making each column sequentially undergo “adsorption → elution → purification → regeneration” through 6 fixed bed columns in series + periodic valve switching, so that the feed is continuously processed without interruption, and the product is continuously produced without interruption. During continuous operation, the mixed solution can be stably treated without production interruption, and continuous separation is realized. In contrast, in the technical solution of Comparative Example 3, a fixed bed chromatographic column is used to separate the mixed aqueous solution of lithium dihydrogen phosphate and inositol, which requires stopping the feed during the switching stage, and the separation process cannot be continuous, which is time-consuming and labor-intensive, and cannot meet the needs of industrial large-scale production. Second, in terms of concentration and purity of the product, the SMB device of Example 2 can precisely control the flow direction of the material through “multi-column zoning”, ensuring that the lithium dihydrogen phosphate and inositol effluent are not cross-contaminated and the purity is stable. The fixed bed chromatographic column selected in Comparative Example 3 is prone to cross-contamination of lithium dihydrogen phosphate and inositol effluent, resulting in significant fluctuations in purity, which can cause some batches to fail to meet the standards and reduce production, thereby increasing unit cost.

[0096] Therefore, in the technical solution of the present application, the SMB device realizes the co-production of lithium dihydrogen phosphate and inositol through continuous, high utilization rate and high precision separation, which can not only meet the stringent purity requirements of battery-grade lithium dihydrogen phosphate, but also realize the high-value recovery of inositol. The fixed bed chromatographic column cannot achieve this purpose.

[0097] Example 3 A production method for co-producing lithium dihydrogen phosphate and inositol, comprising the following steps: S101 in S10 is the same as that in Example 1; S102. The white spherical resin is obtained by mixing styrene-divinylbenzene and ethyl acrylate at a mass ratio of 15-100, reacting at 80°C for 7h, then increasing the temperature to 95°C and continuing to react for 3h. Then, the white spherical resin is subjected to chloromethylation catalytic reaction with ZnCl2 at 70°C for 5h, and then subjected to amine reaction and quaternary amine reaction with ethylenediamine and chloroethanol at 75°C, respectively, for 2h to obtain a chloroethanol quaternary amine anion exchange resin. The chloroethanol quaternary amine anion exchange resin is packed in a column, and then the phytic acid solution obtained in S10 is injected into the column at a flow rate of 1.0 bv / h until the resin is saturated, which is indicated by the phytic acid concentration in the outlet flow of the resin column being less than 2%. After adsorption is completed, the impurities in the resin are eluted with deionized water until the content of sodium, potassium and other impurity ions in the eluate is less than 5 ppm, and an anion exchange resin adsorbed with phytate ions is obtained.

[0098] S20. A 5.0 mol / L lithium chloride (LiCl) solution is mixed with a 2.0 mol / L hydrochloric acid (HCl) solution at a volume ratio of 1:1 to obtain a mixed desorption solution. Then, the mixed desorption solution is injected into the anion exchange resin in S20, which has adsorbed phytate ions, at a flow rate of 1.5 BV / h at 25°C, and the amount is 2 BV. When the lithium content at the outlet of the resin column reaches 0.5%, the desorption solution, i.e., lithium phytate solution, is collected, and the concentration is about 12.0%.

[0099] S30. The lithium phytate solution obtained in S20 is passed through a ceramic membrane with a pore size of 0.45-0.5 μm to remove suspended matter, and then concentrated using a nanofiltration membrane with a molecular weight cutoff of 1000 D. The concentration of potassium phytate can reach 35%. Then, the concentrated lithium phytate solution is placed in a high-pressure reaction kettle, heated to 200°C, and maintained at a pressure of 0.7 MPa for 2 h. After the reaction is completed, the system is cooled to room temperature, and a small amount of precipitate is removed by filtration to obtain a mixed hydrolysate containing lithium dihydrogen phosphate and inositol.

[0100] S40. A four-zone simulated moving bed device is set up using cation exchange resin as the stationary phase and deionized water as the mobile phase. The four zones are Z1 (1 column), Z2 (2 columns), Z3 (2 columns), and Z4 (1 column). The six resin columns in the four zones are 100% filled with cation exchange resin, and the sealing of all pipelines and solenoid valve interfaces is checked. Then, the mobile phase pump is turned on to flush the system and remove air bubbles in the resin columns and pipelines. The system is set to a feed flow rate of 1.5 mL / min, and the mixed hydrolysate containing lithium dihydrogen phosphate and inositol obtained in S30 is injected. Periodic switching is performed by the solenoid valve array to make the six columns circulate through the functional zones in the order of "Z1→Z2→Z3→Z4→Z1" with a switching time of 3.5 min. After continuous separation for 3.5 h, lithium dihydrogen phosphate solution and inositol solution are obtained, respectively. The purity of the lithium dihydrogen phosphate solution is ≥99.5%, and the lithium concentration is about 0.75 mol / L. The purity of the inositol solution is ≥98%, and the concentration is about 0.05 mol / L.

[0101] S50 is the same as in Example 1.

[0102] Through S10-S50, a battery-grade lithium dihydrogen phosphate product with a purity of not less than 99.9% and a metal impurity content of less than 10 ppm is obtained. At the same time, an inositol crystal with a purity of about 98.5% is obtained, which is suitable for pharmaceutical or food grade applications.

[0103] In Example 3, Comparative Example 4 is set up. The difference between Comparative Example 4 and Example 3 is that in S20, the concentration of LiCl is 6.5 mol / L, the concentration of HCl is 3 mol / L, LiCl and HCl are mixed in a volume ratio of 2:1 to obtain a mixed desorption solution, and then the mixed desorption solution is injected into the anion exchange resin in which the phytate ions are adsorbed in S20 at a flow rate of 2.5 BV / h at 70°C, and the amount is 5 BV; in S30, the concentrated lithium phytate solution is placed in a high-pressure reaction kettle, heated to 300°C, and kept at a self-pressure of 1.0 MPa for 5 h; in S40, the feeding flow rate is set to 3.5 mL / min, the switching time is 6.5 min, and the continuous separation time is 7 h. The rest are the same as those in Example 3.

[0104] The purity of lithium dihydrogen phosphate and inositol obtained in Example 3 and Comparative Example 4 is determined respectively.

[0105] It can be obtained that the purity of lithium dihydrogen phosphate in Example 3 is greater than 99.9%, and the metal impurity content is less than 8 ppm, which is a battery-grade lithium dihydrogen phosphate; the purity of inositol is greater than 98.5%, which is a pharmaceutical-grade and food-grade inositol. In contrast, the purity of lithium dihydrogen phosphate obtained in Comparative Example 4 is less than 90%, and the metal impurity content is 20 ppm to 30 ppm, which cannot meet the requirements of battery grade; and the purity of inositol is less than 90%, which cannot meet the requirements of pharmaceutical grade or food grade. The reasons for this phenomenon are as follows: In the technical scheme of Comparative Example 4, HCl is 3 mol / L, which will produce a strong acid environment, accelerate the “de-crosslinking” reaction of the styrene-divinylbenzene crosslinked skeleton of the resin, cause the collapse of the resin pore channel, and the high temperature of 70°C will further intensify the “de-alkylation” of the functional groups of the resin, so that the quaternary ammonium group is decomposed into a tertiary amine, losing the positive charge site; at the same time, LiCl 6.5 mol / L is an oversaturated concentration, and the ionic strength is too high, which will cause the resin to swell excessively, release trace amounts of metal impurities, and enter the desorption solution with phytate, ultimately resulting in a significant decrease in the concentration of lithium phytate solution and an increase in the impurity content. In the hydrolysis treatment process, when the temperature is 300°C, the inositol in the solution will undergo a dehydration and carbonization reaction, and the hydroxyl groups (-OH) will successively dehydrate to form double bonds, and finally generate black carbon residue, and the high pressure of 1.0 MPa will intensify the reaction rate, and after 5 h, the carbonization degree will be further intensified; and part of the lithium dihydrogen phosphate in the solution will undergo a thermal decomposition reaction at 300°C to generate lithium diphosphate, which has low solubility in water and will precipitate; ultimately, the conversion rate of lithium dihydrogen phosphate and inositol will be reduced, and the impurity content will increase. In the continuous separation process, the feeding flow rate of 3.5 mL / min will exceed the “resin adsorption-elution equilibrium” capacity, which will cause the inositol content in the lithium dihydrogen phosphate product to increase, and the Li +The content and the purity of the two products are both substandard. Meanwhile, the switching at 6.5 min can cause the resin in the adsorption zone to be fully saturated, and the long residence time of the resin in the regeneration zone can cause H + Excessive adsorption, after the SMB is continuously operated for 7 h, the capacity of the resin is significantly reduced, and the concentrations of lithium dihydrogen phosphate and inositol extracted are significantly reduced. In summary, the purity of the lithium dihydrogen phosphate product and the inositol product is significantly reduced, the impurity content is increased, and the requirements cannot be met.

[0106] In the technical solution of Example 3, there is a synergistic effect between “LiCl concentration + HCl concentration + temperature + flow rate” in the desorption treatment, wherein LiCl provides a high concentration of Li + , and the electrostatic competition destroys the combination of phytate and the resin; HCl provides H + , which interferes with the auxiliary desorption through hydrogen bonds, and the two work together to make the desorption rate reach more than 95%, and avoid the problems of excessive swelling of the resin and corrosion of the resin skeleton caused by too high concentration of a single component; and at 25°C, the diffusion rate of Li + and H + can be increased to match the flow rate of 1.5 BV / h, so that the phytate can be completely desorbed. In the hydrolysis treatment, 200°C can provide enough energy to break the C-O-P bond of phytate, and the pressure of 0.7 MPa can maintain the solution in a liquid state, and the temperature is lower than the carbonization threshold of inositol and the decomposition threshold of lithium dihydrogen phosphate, ensuring that the two products have no side reactions. In the continuous separation process, the feeding flow rate of 1.5 mL / min and the switching time of 3.5 min can ensure that each column sequentially completes “adsorption - elution - purification - regeneration”, avoiding insufficient adsorption caused by too high flow rate or insufficient processing capacity caused by too low flow rate; at the same time, the switching time matches the flow rate of the mobile phase, which can meet the flow balance of “mobile phase = feed + two product extraction” without waste liquid waste; in addition, the running time of 3.5 h can avoid low equipment utilization caused by short running time, and avoid resin overload and impurity accumulation caused by long running time, ensuring that the purity of the products fluctuates by less than 0.5% during continuous running. Therefore, in Example 3, through the mutual cooperation of each step of the process, high-purity lithium dihydrogen phosphate and inositol are obtained, and the co-production of lithium dihydrogen phosphate and inositol is realized.

[0107] According to comparative analysis of examples 1-3 and comparative examples 1-4, in the technical scheme of the application, the process conditions and process parameters of the lithium dihydrogen phosphate co-production inositol production method are an organic whole that is interlocked and mutually supported, and there is a significant synergistic effect. By precisely controlling the desorption strength, hydrolysis conditions, and separation rhythm, the balance of "resin protection - product purity - process economy" is achieved; and after the process conditions or parameters are replaced, the synergistic relationship of each link is broken, leading to resin damage, product side reactions, separation failure, and the purity of the finally obtained lithium dihydrogen phosphate and inositol is reduced, the impurity content is increased, and the industrialization value is lost. This shows that the parameter design of the co-production technology of the application has strong correlation, and a single parameter cannot be adjusted, and optimization needs to be based on the whole process balance.

[0108] The above is only the preferred embodiment of the application, and does not limit the patent scope of the application, and any equivalent structure or equivalent flow transformation based on the content of the specification and drawings, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the application.

Claims

1. A method for producing lithium dihydrogen phosphate co-produced with inositol, characterized by, The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps:

2. The production method according to claim 1, characterized by, The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps:

3. The production method according to claim 1, characterized by, The production method comprises the following steps:

4. The production method according to claim 1, characterized by, The production method comprises the following steps:

5. The production method according to claim 1, characterized by, The production method comprises the following steps:

6. The production method according to claim 1, characterized by, The production method comprises the following steps: The production method comprises the following steps:

7. The production method according to claim 6, characterized by, The production method comprises the following steps:

8. The production method according to claim 1, characterized by, The production method comprises the following steps:

9. Lithium dihydrogen phosphate, characterized in that, The production method comprises the following steps:

10. The lithium phosphate of claim 9, wherein, The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps: The production method comprises the following steps:

Images