CN114180602B - Preparation method of lithium hexafluorophosphate - Google Patents
Preparation method of lithium hexafluorophosphate Download PDFInfo
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- CN114180602B CN114180602B CN202111447249.3A CN202111447249A CN114180602B CN 114180602 B CN114180602 B CN 114180602B CN 202111447249 A CN202111447249 A CN 202111447249A CN 114180602 B CN114180602 B CN 114180602B
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- lithium hexafluorophosphate
- lithium fluoride
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- -1 lithium hexafluorophosphate Chemical compound 0.000 title claims abstract description 105
- 238000002360 preparation method Methods 0.000 title claims abstract description 24
- PQXKHYXIUOZZFA-UHFFFAOYSA-M lithium fluoride Chemical compound [Li+].[F-] PQXKHYXIUOZZFA-UHFFFAOYSA-M 0.000 claims abstract description 198
- 239000007788 liquid Substances 0.000 claims abstract description 62
- 239000000203 mixture Substances 0.000 claims abstract description 43
- 239000006185 dispersion Substances 0.000 claims abstract description 36
- ZMANZCXQSJIPKH-UHFFFAOYSA-N Triethylamine Chemical compound CCN(CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-N 0.000 claims abstract description 33
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims abstract description 30
- 238000002156 mixing Methods 0.000 claims abstract description 28
- 239000002994 raw material Substances 0.000 claims abstract description 26
- 238000001354 calcination Methods 0.000 claims abstract description 25
- 239000011230 binding agent Substances 0.000 claims abstract description 24
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 22
- 238000001035 drying Methods 0.000 claims abstract description 21
- 238000002485 combustion reaction Methods 0.000 claims abstract description 19
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 17
- 239000012025 fluorinating agent Substances 0.000 claims abstract description 14
- 238000001914 filtration Methods 0.000 claims abstract description 12
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 11
- 238000003756 stirring Methods 0.000 claims abstract description 11
- DDFHBQSCUXNBSA-UHFFFAOYSA-N 5-(5-carboxythiophen-2-yl)thiophene-2-carboxylic acid Chemical compound S1C(C(=O)O)=CC=C1C1=CC=C(C(O)=O)S1 DDFHBQSCUXNBSA-UHFFFAOYSA-N 0.000 claims abstract description 10
- 238000004519 manufacturing process Methods 0.000 claims abstract description 9
- UHZYTMXLRWXGPK-UHFFFAOYSA-N phosphorus pentachloride Chemical compound ClP(Cl)(Cl)(Cl)Cl UHZYTMXLRWXGPK-UHFFFAOYSA-N 0.000 claims abstract description 9
- 238000010438 heat treatment Methods 0.000 claims description 58
- 239000010902 straw Substances 0.000 claims description 48
- 239000002245 particle Substances 0.000 claims description 35
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 34
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 24
- 229910052799 carbon Inorganic materials 0.000 claims description 24
- 239000000843 powder Substances 0.000 claims description 24
- 238000000034 method Methods 0.000 claims description 19
- 239000003610 charcoal Substances 0.000 claims description 13
- 108010010803 Gelatin Proteins 0.000 claims description 10
- 229920000159 gelatin Polymers 0.000 claims description 10
- 239000008273 gelatin Substances 0.000 claims description 10
- 235000019322 gelatine Nutrition 0.000 claims description 10
- 235000011852 gelatine desserts Nutrition 0.000 claims description 10
- 238000007790 scraping Methods 0.000 claims description 9
- 239000008367 deionised water Substances 0.000 claims description 8
- 229910021641 deionized water Inorganic materials 0.000 claims description 8
- 229920001495 poly(sodium acrylate) polymer Polymers 0.000 claims description 8
- NNMHYFLPFNGQFZ-UHFFFAOYSA-M sodium polyacrylate Chemical group [Na+].[O-]C(=O)C=C NNMHYFLPFNGQFZ-UHFFFAOYSA-M 0.000 claims description 8
- 238000005406 washing Methods 0.000 claims description 8
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 7
- 229920002472 Starch Polymers 0.000 claims description 7
- 229910000040 hydrogen fluoride Inorganic materials 0.000 claims description 7
- 238000004321 preservation Methods 0.000 claims description 7
- 239000008107 starch Substances 0.000 claims description 7
- 235000019698 starch Nutrition 0.000 claims description 7
- 238000000967 suction filtration Methods 0.000 claims description 7
- 235000017166 Bambusa arundinacea Nutrition 0.000 claims description 6
- 235000017491 Bambusa tulda Nutrition 0.000 claims description 6
- 241001330002 Bambuseae Species 0.000 claims description 6
- 235000015334 Phyllostachys viridis Nutrition 0.000 claims description 6
- 239000011425 bamboo Substances 0.000 claims description 6
- IKGLACJFEHSFNN-UHFFFAOYSA-N hydron;triethylazanium;trifluoride Chemical compound F.F.F.CCN(CC)CC IKGLACJFEHSFNN-UHFFFAOYSA-N 0.000 claims description 6
- 239000001913 cellulose Substances 0.000 claims description 5
- 229920002678 cellulose Polymers 0.000 claims description 5
- 238000006243 chemical reaction Methods 0.000 claims description 5
- 238000001816 cooling Methods 0.000 claims description 5
- 238000004140 cleaning Methods 0.000 claims description 4
- 239000004094 surface-active agent Substances 0.000 claims description 4
- OBCUTHMOOONNBS-UHFFFAOYSA-N phosphorus pentafluoride Chemical compound FP(F)(F)(F)F OBCUTHMOOONNBS-UHFFFAOYSA-N 0.000 claims description 3
- 239000000853 adhesive Substances 0.000 claims 3
- 230000001070 adhesive effect Effects 0.000 claims 3
- 230000009286 beneficial effect Effects 0.000 abstract description 5
- 238000004904 shortening Methods 0.000 abstract description 3
- 230000000052 comparative effect Effects 0.000 description 21
- 239000000463 material Substances 0.000 description 19
- 239000000243 solution Substances 0.000 description 18
- 239000000047 product Substances 0.000 description 15
- 239000000523 sample Substances 0.000 description 14
- LSKXXERVYUDTMF-UHFFFAOYSA-N N,N-diethylethanamine pentafluoro-lambda5-phosphane Chemical compound P(F)(F)(F)(F)F.C(C)N(CC)CC LSKXXERVYUDTMF-UHFFFAOYSA-N 0.000 description 11
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 6
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 6
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 6
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 6
- 239000012470 diluted sample Substances 0.000 description 6
- 239000012535 impurity Substances 0.000 description 6
- 229910052744 lithium Inorganic materials 0.000 description 6
- 229910001416 lithium ion Inorganic materials 0.000 description 6
- 239000011259 mixed solution Substances 0.000 description 6
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 5
- 238000002835 absorbance Methods 0.000 description 5
- 239000000706 filtrate Substances 0.000 description 5
- 239000011521 glass Substances 0.000 description 5
- 239000012299 nitrogen atmosphere Substances 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 239000004576 sand Substances 0.000 description 5
- 239000004698 Polyethylene Substances 0.000 description 4
- 238000013329 compounding Methods 0.000 description 4
- 239000008187 granular material Substances 0.000 description 4
- 229910017053 inorganic salt Inorganic materials 0.000 description 4
- 229920000573 polyethylene Polymers 0.000 description 4
- 239000002244 precipitate Substances 0.000 description 4
- 238000005303 weighing Methods 0.000 description 4
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 3
- 239000001569 carbon dioxide Substances 0.000 description 3
- 229910002092 carbon dioxide Inorganic materials 0.000 description 3
- 238000001514 detection method Methods 0.000 description 3
- 238000007865 diluting Methods 0.000 description 3
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 3
- 239000003792 electrolyte Substances 0.000 description 3
- 238000000227 grinding Methods 0.000 description 3
- 239000011265 semifinished product Substances 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 2
- 229920002565 Polyethylene Glycol 400 Polymers 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- DBMJMQXJHONAFJ-UHFFFAOYSA-M Sodium laurylsulphate Chemical compound [Na+].CCCCCCCCCCCCOS([O-])(=O)=O DBMJMQXJHONAFJ-UHFFFAOYSA-M 0.000 description 2
- ZRBROGSAUIUIJE-UHFFFAOYSA-N azanium;azane;chloride Chemical compound N.[NH4+].[Cl-] ZRBROGSAUIUIJE-UHFFFAOYSA-N 0.000 description 2
- 230000000740 bleeding effect Effects 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 238000003763 carbonization Methods 0.000 description 2
- 238000010924 continuous production Methods 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 239000002270 dispersing agent Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000010030 laminating Methods 0.000 description 2
- JLFNLZLINWHATN-UHFFFAOYSA-N pentaethylene glycol Chemical compound OCCOCCOCCOCCOCCO JLFNLZLINWHATN-UHFFFAOYSA-N 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 230000009257 reactivity Effects 0.000 description 2
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 229920002261 Corn starch Polymers 0.000 description 1
- 240000008042 Zea mays Species 0.000 description 1
- 235000005824 Zea mays ssp. parviglumis Nutrition 0.000 description 1
- 235000002017 Zea mays subsp mays Nutrition 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 235000011114 ammonium hydroxide Nutrition 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000012490 blank solution Substances 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 239000007853 buffer solution Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 235000005822 corn Nutrition 0.000 description 1
- 239000008120 corn starch Substances 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000011010 flushing procedure Methods 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 239000003517 fume Substances 0.000 description 1
- 238000001027 hydrothermal synthesis Methods 0.000 description 1
- 238000011534 incubation Methods 0.000 description 1
- 229910003002 lithium salt Inorganic materials 0.000 description 1
- 159000000002 lithium salts Chemical class 0.000 description 1
- IGILRSKEFZLPKG-UHFFFAOYSA-M lithium;difluorophosphinate Chemical compound [Li+].[O-]P(F)(F)=O IGILRSKEFZLPKG-UHFFFAOYSA-M 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000012488 sample solution Substances 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 239000012086 standard solution Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 239000012085 test solution Substances 0.000 description 1
- NRZGVGVFPHPXEO-UHFFFAOYSA-M tetraphenylarsanium;chloride Chemical compound [Cl-].C1=CC=CC=C1[As+](C=1C=CC=CC=1)(C=1C=CC=CC=1)C1=CC=CC=C1 NRZGVGVFPHPXEO-UHFFFAOYSA-M 0.000 description 1
- 238000001291 vacuum drying Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D15/00—Lithium compounds
- C01D15/005—Lithium hexafluorophosphate
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The application relates to the technical field of battery production, and particularly discloses a preparation method of a lithium hexafluorophosphate preparation method. The preparation method of the lithium hexafluorophosphate comprises the following steps: (1) Uniformly mixing phosphorus pentachloride, triethylamine and a fluorinating agent to obtain a raw material liquid; (2) Mixing lithium hydroxide, ammonium fluoride, a pore-forming agent, a combustion improver and a binder dispersion liquid, uniformly stirring, and drying to obtain a lithium fluoride mixture; (3) Calcining the lithium fluoride mixture to constant weight at 700-750 ℃ to obtain porous lithium fluoride; (4) Uniformly mixing porous lithium fluoride with raw material liquid under the protection of nitrogen, preserving heat for 60-80min at 5-15 ℃, filtering and concentrating under reduced pressure to obtain crude lithium hexafluorophosphate, and purifying the crude lithium hexafluorophosphate to obtain the lithium hexafluorophosphate. The porous lithium fluoride can increase the generation rate of lithium hexafluorophosphate and is beneficial to shortening the time required for producing lithium hexafluorophosphate.
Description
Technical Field
The application relates to the technical field of battery production, in particular to a preparation method of lithium hexafluorophosphate.
Background
The lithium ion battery is a rechargeable battery with no pollution, long cycle life and high cycle efficiency, and is widely used in small-sized mobile power supplies, electric automobiles and electric bicycles. The electrolyte lithium salt is the main component of lithium ion battery electrolyte, and more commonly used types include lithium difluorooxalato borate, lithium difluorophosphate, lithium hexafluorophosphate and the like. Among these, the dominant lithium electrolyte salt is lithium hexafluorophosphate.
In the related art, there is a method for preparing lithium hexafluorophosphate, comprising the following steps: (1) Uniformly mixing 20.8kg of phosphorus pentachloride solid, 100L of triethylamine and 10kg of fluorinating agent under the protection of nitrogen, preserving the temperature at 5 ℃ for 4 hours, and filtering to remove hydrochloride to obtain a mixed solution of phosphorus pentafluoride triethylamine complex; in the step, the fluorinating agent is liquid hydrogen fluoride; (2) Under the protection of nitrogen, weighing anhydrous lithium fluoride, adding the anhydrous lithium fluoride into a ball mill, grinding to obtain anhydrous lithium fluoride powder, and uniformly stirring 3kg of anhydrous lithium fluoride powder, 0.15kg of PEG400 dispersing agent and 10L of triethylamine to obtain a lithium fluoride mixture; (3) Adding the mixed solution of the phosphorus pentafluoride triethylamine complex into a lithium fluoride mixture under the nitrogen atmosphere at the temperature of 5 ℃, then preserving the heat for 4 hours at the temperature of 10 ℃, filtering to remove unreacted lithium fluoride, concentrating the filtrate under reduced pressure to obtain crude lithium hexafluorophosphate, fully mixing and filtering the crude lithium hexafluorophosphate with 100L of dimethyl carbonate (purity 99.98% and water content of 8 ppm) under the nitrogen atmosphere at the temperature of 20 ℃, concentrating and crystallizing the filtrate to obtain a semi-finished product of lithium hexafluorophosphate, and then drying in vacuum for 24 hours at the temperature of 30 ℃ and 5mmHg to obtain the lithium hexafluorophosphate.
In view of the above-mentioned related art, the inventors believe that although the preparation of lithium hexafluorophosphate is achieved in the related art, the solubility of lithium fluoride in triethylamine is poor, and the phosphorus pentafluoride triethylamine complex in the mixed solution can only react on the surface of anhydrous lithium fluoride powder, affecting the rate of formation of lithium hexafluorophosphate.
Disclosure of Invention
In the related art, the phosphorus pentafluoride triethylamine complex can only react on the surface of anhydrous lithium fluoride powder, and the generation rate of lithium hexafluorophosphate is affected. To ameliorate this disadvantage, the present application provides a method of preparing lithium hexafluorophosphate.
The application provides a preparation method of lithium hexafluorophosphate, which adopts the following technical scheme:
a method for preparing lithium hexafluorophosphate, comprising the following steps:
(1) Uniformly mixing phosphorus pentachloride, triethylamine and a fluorinating agent under the protection of nitrogen, and then reacting for 3-5 hours at 5-10 ℃ to obtain a raw material liquid, wherein the fluorinating agent is used for converting the phosphorus pentachloride into phosphorus pentafluoride;
(2) Mixing 24 parts of lithium hydroxide, 37 parts of ammonium fluoride, 20-24 parts of pore-forming agent, 6-10 parts of combustion improver and 30-50 parts of binder dispersion liquid with the water content of 70-80%, uniformly stirring, and drying the mixed product to obtain a lithium fluoride mixture; in this step, the calcined product of the pore-forming agent is in a gaseous state under the reaction conditions;
(3) Calcining the lithium fluoride mixture to constant weight at 700-750 ℃ to obtain porous lithium fluoride, and cooling the porous lithium fluoride to room temperature for later use;
(4) Uniformly mixing porous lithium fluoride with raw material liquid under the protection of nitrogen, preserving heat for 60-80min at 5-15 ℃, filtering and concentrating under reduced pressure to obtain crude lithium hexafluorophosphate, and purifying the crude lithium hexafluorophosphate to obtain the lithium hexafluorophosphate.
By adopting the technical scheme, compared with the related art, the preparation method comprises the steps of preparing raw material liquid containing phosphorus pentafluoride triethylamine complex, preparing and calcining the lithium fluoride mixture to obtain porous lithium fluoride, and finally using the porous lithium fluoride to replace anhydrous lithium fluoride powder in the related art, and reacting the porous lithium fluoride with the phosphorus pentafluoride triethylamine complex in the raw material liquid to obtain the lithium hexafluorophosphate. Because the porous lithium fluoride has larger specific surface area compared with the lithium fluoride powder, the contact between the phosphorus pentafluoride triethylamine complex and the lithium fluoride is more sufficient, thereby improving the production rate of the lithium hexafluorophosphate and shortening the time required for producing the lithium hexafluorophosphate.
In step (2) of the present application, the lithium hydroxide and the ammonium fluoride are reacted with water after encountering the binder dispersion to produce ammonia monohydrate and lithium fluoride, the lithium fluoride is mixed with the binder dispersion, the pore-forming agent and the combustion improver to form a lithium fluoride mixture, the lithium fluoride mixture is dried to lose moisture and is preliminarily shaped, and then the shaped lithium fluoride mixture is calcined in step (3). In the calcination process, the combustion improver releases heat, so that the lithium fluoride mixture is heated more uniformly. After calcination, the ammonia monohydrate decomposes into ammonia gas and water vapor, the pore-forming agent also converts into a gaseous calcination product, and the calcination product of the pore-forming agent and the water vapor and ammonia gas diffuse to produce pores in the lithium fluoride mixture, thereby converting the lithium fluoride mixture into porous lithium fluoride.
Preferably, in the step (2) of preparing lithium hexafluorophosphate, 24 parts of lithium hydroxide, 37 parts of ammonium fluoride, 21-23 parts of pore-forming agent, 7-9 parts of combustion improver and 35-45 parts of binder dispersion liquid with the water content of 70-80% are mixed and stirred uniformly, and a lithium fluoride mixture is obtained after drying.
By adopting the technical scheme, the raw material ratio of the lithium fluoride mixture is optimized, the generation rate of lithium hexafluorophosphate is further improved, and the time required for producing the lithium hexafluorophosphate is shortened.
Preferably, the fluorinating agent in the step (1) is liquid hydrogen fluoride or triethylamine trihydrofluoride.
By adopting the technical scheme, the liquid hydrogen fluoride or the triethylamine trihydrofluoride can convert phosphorus pentachloride into phosphorus pentafluoride, and the liquid hydrogen fluoride has stronger corrosiveness, so that when the triethylamine trihydrofluoride is selected, the loss of production equipment can be reduced, and the triethylamine trihydrofluoride and triethylamine have better compatibility, thereby being beneficial to improving the uniformity of a reaction system in the step (1).
Preferably, the pore-forming agent in the step (2) is starch or powdery cellulose.
By adopting the technical scheme, the calcined product of the starch or the powdery cellulose is in a gaseous state under the reaction condition, and the starch is easier to swell compared with the powdery cellulose, and the swelled starch can improve the viscosity of the binder dispersion liquid, so that the possibility of bleeding in the placing process of the lithium fluoride mixture is reduced, and the uniformity of the lithium fluoride mixture is improved.
Preferably, the binder dispersion is prepared from a binder and deionized water, wherein the binder is sodium polyacrylate or gelatin.
By adopting the technical scheme, sodium polyacrylate and gelatin can be used as binders after being dissolved in water, wherein main calcined products of gelatin comprise ammonia gas, carbon dioxide and water vapor, and calcined products of sodium polyacrylate are carbonate. Ammonia, carbon dioxide and water vapor may all leave the calcination system directly, while carbonate remains in the subsequent steps of calcination, resulting in a decrease in the purity of the porous lithium fluoride, and thus binder dispersions formulated from gelatin are more suitable.
Preferably, the combustion improver in the step (2) is bamboo charcoal particles or straw charcoal particles.
Through adopting above-mentioned technical scheme, bamboo charcoal granule and straw charcoal granule all have higher calorific value to under the reaction condition of this application, combustion product is carbon dioxide, but the production of bamboo charcoal receives the restriction of bamboo timber regional distribution, and straw charcoal then can directly use the straw to prepare, and the raw materials source is extensive. Therefore, when the straw carbon is used as the combustion improver, the cost for preparing the porous lithium fluoride to synthesize the lithium hexafluorophosphate is lower, and the method is convenient to popularize.
Preferably, the combustion improver in the step (2) is straw carbon particles, and the straw carbon particles are prepared according to the following steps:
(1) Drying the straw at 70-85 ℃ until the water content is 0.6-1.0%, and then crushing the straw until the average particle size is 500-700 mu m to obtain straw powder;
(2) Uniformly mixing straw powder with a washing liquid to obtain a straw powder dispersion liquid, heating the straw powder dispersion liquid to 280-320 ℃ in a closed environment, then preserving heat for 60-80min, and stopping heating to obtain a carbon particle dispersion liquid;
(3) And carrying out suction filtration on the carbon particle dispersion liquid, and then cleaning and drying a suction filtration product to obtain straw carbon particles.
By adopting the technical scheme, in the method for preparing the straw carbon particles, firstly, straw powder is prepared by taking straw as a raw material in the step (1), then the straw powder is carbonized through a hydrothermal method in the step (2) to obtain carbon particle dispersion liquid, and finally, the straw carbon particles are extracted from the carbon particle dispersion liquid. After the carbon particle dispersion liquid is obtained in the step (2), the washing liquid can dissolve inorganic salt remained in the carbon particles, reduce impurities in the straw carbon particles and help to improve the purity of lithium hexafluorophosphate.
Preferably, the washing liquid is deionized water or surfactant solution with water content of 80% -85%.
By adopting the technical scheme, the deionized water and the surfactant solution can dissolve inorganic salt remained in the carbon particles, but the surfactant solution can dissolve tar generated in the carbonization process of straw parts besides the inorganic salt, thereby being beneficial to reducing impurities in the few straw carbon particles and improving the purity of lithium hexafluorophosphate.
Preferably, porous lithium fluoride is prepared in calcining device, calcining device includes heating jar, oven, heating element, compounding subassembly and insulating tube, heating element is used for heating the heating jar, the compounding subassembly is used for making the raw materials of porous lithium fluoride mix with stirring in the oven into the lithium fluoride mixture, the oven is fixed to be set up on the heating jar, the oven passes through feeding member and heating jar intercommunication, the feeding member includes funnel and conveying tube, the one end and the oven intercommunication of funnel, the other end with the conveying tube intercommunication, the one end and the heating jar intercommunication of funnel are kept away from to the conveying tube, be provided with the valve on the conveying tube, the both ends of insulating tube all communicate with the heating jar, the insulating tube is around establishing on the outer wall of oven, and with the outer wall laminating of oven.
By adopting the technical scheme, when the step (2) is carried out, lithium hydroxide, ammonium fluoride, pore-forming agent, combustion improver and binder dispersion liquid are firstly arranged in a drying oven, then the raw materials in the drying oven are uniformly mixed by a mixing component, and the mixture of the raw materials is heated by the drying oven to obtain the lithium fluoride mixture. Then, the valve on the feed pipe is opened, the lithium fluoride mixture enters the heating tank, and then the valve is closed again. In step (3), the heating assembly heats the lithium fluoride mixture in the heating tank and calcines the lithium fluoride mixture into porous lithium fluoride. Meanwhile, hot air generated in the heating process enters the heat preservation pipe, and the heat preservation pipe heats air in the oven, so that not only is the energy consumption of the oven reduced in heating, but also the raw materials for producing porous lithium fluoride in the next batch can be heated in advance, thereby realizing continuous production of the porous lithium fluoride and being beneficial to improving the efficiency of preparing lithium hexafluorophosphate.
Preferably, the compounding subassembly includes motor, pivot, helical blade and scraper blade, the motor is fixed to be set up in the oven outside, the output and the pivot coaxial coupling of motor, helical blade and pivot coaxial coupling, in the pivot was worn into the oven, scraper blade fixed connection is in the pivot, and with the inside wall laminating of funnel.
Through adopting above-mentioned technical scheme, in step (2), motor drive pivot rotates, and the pivot drives helical blade and scraper blade and rotates jointly, and scraper blade and helical blade mix the material in the oven, have improved the degree of consistency of material. After the step (2) is finished, the scraping plate scrapes the materials remained on the funnel wall, so that the cleaning of the residual materials is realized, and the waste of the materials is reduced.
In summary, the present application has the following beneficial effects:
1. according to the method, the lithium fluoride mixture is prepared by taking lithium hydroxide and ammonium fluoride as main raw materials, and then the lithium fluoride mixture is calcined to prepare the porous lithium fluoride. Then, the porous lithium fluoride is reacted with the phosphorus pentafluoride triethylamine complex in the raw material liquid to generate lithium hexafluorophosphate. Because the porous lithium fluoride has larger specific surface area compared with the lithium fluoride powder prepared by simple grinding, the porous lithium fluoride has higher reactivity, thereby improving the production rate of lithium hexafluorophosphate and shortening the time required for producing the lithium hexafluorophosphate.
2. Sodium polyacrylate or gelatin is preferred as a raw material for preparing the binder dispersion liquid in the application, wherein the calcined product of gelatin is a gaseous substance under the calcining condition, and sodium carbonate is a solid substance in the calcined product of sodium polyacrylate, so that impurities in porous lithium fluoride can be reduced when the binder dispersion liquid is prepared by using gelatin, and the purity of lithium hexafluorophosphate can be improved.
3. According to the method, the calcining device is designed, the step (2) and the step (3) of preparing the lithium hexafluorophosphate are realized through the calcining device, in the step (3), the hot air flow generated during calcining can heat the oven, so that not only is the energy consumed by the oven saved, but also the raw material for producing the porous lithium fluoride in the next batch is heated in advance, the continuous production of the porous lithium fluoride is realized, and the production efficiency of the lithium hexafluorophosphate is improved.
Drawings
Fig. 1 is a schematic view of the overall structure of the calcination apparatus according to the embodiment of the present application.
Fig. 2 is a schematic structural view of an embodiment of the present application for illustrating a mixing assembly.
Reference numerals illustrate:
1. a heating tank; 2. an oven; 3. a heating assembly; 31. heating the base; 4. a mixing component; 41. a motor; 42. a rotating shaft; 43. A helical blade; 44. a scraper; 5. a heat preservation pipe; 6. a discharge pipe; 7. a support rod; 8. a feeding member; 81. a funnel; 82. a feed pipe; 9. a feed pipe; 10. a valve; 11. and (5) mounting a frame.
Detailed Description
The present application is further described in detail below in conjunction with the preparation examples, and figures 1 and 2.
The raw materials used in the preparation example of the application can be obtained through market, wherein the straw is corn straw provided by Shandong five-sign ecological agriculture technology Co.
Preparation examples of the straw charcoal particles are described below by taking preparation example 1 as an example.
Preparation example 1
In the application, the straw carbon particles are prepared according to the following method:
(1) Drying the straw at 75 ℃ until the water content is 0.8%, and crushing the straw until the average particle size is 650 mu m to obtain straw powder;
(2) Uniformly mixing 100kg of straw powder with 200kg of washing liquid to obtain straw powder dispersion liquid, heating the straw powder dispersion liquid to 300 ℃ in a closed container, then preserving heat for 70min, and stopping heating to obtain carbon particle dispersion liquid; in the step, the washing liquid is deionized water;
(3) And carrying out suction filtration on the carbon particle dispersion liquid, and then cleaning and drying a suction filtration product to obtain straw carbon particles.
Preparation example 2
The difference between this preparation example and preparation example 1 is that the washing solution is a sodium dodecyl sulfate solution with a water content of 82%.
Examples
The starting materials used in the examples herein are all commercially available.
Examples 1 to 5
The following description will take example 1 as an example.
Example 1
This embodiment provides a calcination device, referring to fig. 1, calcination device includes heating jar 1, oven 2, heating element 3, compounding subassembly 4 and insulating tube 5, and heating element 3 includes heating base 31, and heating base 31 is fixed to be set up subaerial, and heating base 31 top and the bottom fixed connection of heating jar 1, fixedly connected with arranges material pipe 6 on the lateral wall of heating jar 1, arranges material pipe 6 and heating jar 1 intercommunication. The top end of the heating tank 1 is fixedly connected with a supporting rod 7, the top end of the supporting rod 7 is fixedly connected with the oven 2, and the oven 2 is communicated with the heating tank 1 through a feeding piece 8. The top of the oven 2 is provided with a feeding pipe 9, and the feeding pipe 9 is communicated with the oven 2. The heat preservation pipe 5 is fixedly connected to the top end of the heating tank 1, and two ends of the heat preservation pipe 5 are communicated with the heating tank 1. The heat preservation pipe 5 is wound on the outer side wall of the oven 2 and is attached to the outer side wall of the oven 2.
Referring to fig. 1, the feeding member 8 includes a funnel 81 and a feeding pipe 82, wherein, one end of the funnel 81 with a larger caliber is fixedly connected and communicated with the bottom end of the oven 2, one end of the funnel 81 with a smaller caliber is fixedly connected and communicated with the feeding pipe 82, one end of the feeding pipe 82 far away from the funnel 81 is communicated with the heating tank 1, and a valve 10 is fixedly connected on the feeding pipe 82.
Referring to fig. 2, the mixing assembly 4 includes a motor 41, a shaft 42, a helical blade 43, and a scraper 44. The top end of the oven 2 is fixedly connected with a mounting frame 11, and a motor 41 is fixedly connected with the mounting frame 11. The rotating shaft 42 is coaxially arranged and fixedly connected with the output end of the motor 41, and the rotating shaft 42 penetrates into the oven 2 from top to bottom. The spiral blade 43 and the scraping plate 44 are arranged in the oven 2, and the spiral blade 43 and the rotating shaft 42 are coaxially arranged and fixedly connected; the scraping plates 44 are arranged in two, the two scraping plates 44 are arranged in a mutually deviating mode along the radial direction of the rotating shaft 42, the scraping plates 44 are fixedly connected with the rotating shaft 42, and one side, away from the rotating shaft 42, of each scraping plate 44 is attached to the inner wall of the funnel 81.
Referring to fig. 1 and 2, when the calcining apparatus is required to process the material, an operator blocks the discharge pipe 6, then feeds the material into the oven 2 through the feed pipe 9, then the valve 10 blocks the material, and simultaneously the motor 41 drives the screw blade 43 and the scraper 44 through the rotating shaft 42 to stir the material. After the materials are stirred uniformly, the oven 2 dries the materials. After the drying is finished, the valve 10 is opened, the dried materials sequentially enter the heating tank 1 through the funnel 81 and the feeding pipe 82, and meanwhile, the scraping plate 44 scrapes the residual materials on the inner wall of the funnel 81, so that the loss of the materials is reduced. Then, the heating base 31 calcines the material in the heating tank 1, and after the calcination is finished, the operator releases the blocking of the discharge pipe 6 and takes out the material through the discharge pipe 6, so that the processing of the material can be completed.
In example 1, both the step (2) and the step (3) of preparing lithium hexafluorophosphate are realized by the calcining apparatus shown in fig. 1 and 2, and the preparation method of lithium hexafluorophosphate comprises the following steps:
(1) Uniformly mixing 20.8kg of phosphorus pentachloride, 100L of triethylamine and 10kg of fluorinating agent under the protection of nitrogen, and then reacting for 4 hours at 7 ℃ to obtain a raw material liquid; in the step, the fluorinating agent is liquid hydrogen fluoride;
(2) Adding 2.4kg of lithium hydroxide, 3.7kg of ammonium fluoride, 2kg of pore-forming agent, 0.6kg of combustion improver and 3kg of binder dispersion liquid with the water content of 75% into an oven, mixing and stirring uniformly, and drying the mixed product to obtain a lithium fluoride mixture; in the step, the pore-forming agent is powdery cellulose (average particle diameter 300 mu m), the combustion improver is bamboo charcoal particles (average particle diameter 600 mu m), the binder dispersion liquid is sodium polyacrylate aqueous solution (average molecular weight of sodium polyacrylate is 5000);
(3) Heating the heating tank to 720 ℃, calcining the lithium fluoride mixture in the heating tank to constant weight to obtain porous lithium fluoride, and cooling the porous lithium fluoride to room temperature for later use;
(4) Uniformly mixing porous lithium fluoride with raw material liquid under the protection of nitrogen, preserving heat at 10 ℃ for 65min, filtering to obtain crude lithium hexafluorophosphate (mixed liquid), fully mixing the crude lithium hexafluorophosphate with 150L of dimethyl carbonate (purity 99.98% and water content 8 ppm) under the nitrogen atmosphere at 20 ℃ and filtering, concentrating and crystallizing the filtrate to obtain a lithium hexafluorophosphate semi-finished product, and then vacuum drying at 30 ℃ for 24 hours under the condition of 5mmHg to obtain the lithium hexafluorophosphate.
As shown in Table 1, examples 1 to 5 are different in mainly the raw material ratios of the lithium fluoride mixture in the step (2).
TABLE 1
Example 6
This example differs from example 3 in that the fluorinating agent of step (1) is selected from the group consisting of triethylamine trifluoride in an amount of 28.5kg by weight.
Example 7
The difference between this example and example 6 is that the pore-forming agent of step (2) is corn starch.
Example 8
This example differs from example 3 in that the binder solution of step (2) is formulated from gelatin (having an average molecular weight of 55000) and deionized water.
Example 9
The difference between this example and example 8 is that the combustion improver in step (2) is the straw charcoal granules of preparation example 1.
Example 10
The difference between this example and example 9 is that the combustion improver in step (2) is the straw charcoal granules of preparation example 2.
Comparative example
Comparative example 1
A preparation method of lithium hexafluorophosphate, which comprises the following steps:
(1) Uniformly mixing 20.8kg of phosphorus pentachloride solid, 100L of triethylamine and 10kg of fluorinating agent under the protection of nitrogen, preserving the temperature at 5 ℃ for 4 hours, and filtering to remove hydrochloride to obtain a mixed solution of phosphorus pentafluoride triethylamine complex; in the step, the fluorinating agent is liquid hydrogen fluoride;
(2) Under the protection of nitrogen, weighing anhydrous lithium fluoride, adding the anhydrous lithium fluoride into a ball mill, grinding to obtain anhydrous lithium fluoride powder, and uniformly stirring 3kg of anhydrous lithium fluoride powder, 0.15kg of PEG400 dispersing agent and 10L of triethylamine to obtain a lithium fluoride mixture;
(3) Adding the mixed solution of the phosphorus pentafluoride triethylamine complex into a lithium fluoride mixture under the nitrogen atmosphere at the temperature of 5 ℃, then preserving the heat for 4 hours at the temperature of 10 ℃, filtering to remove unreacted lithium fluoride, concentrating the filtrate under reduced pressure to obtain crude lithium hexafluorophosphate, fully mixing and filtering the crude lithium hexafluorophosphate with 100L of dimethyl carbonate (purity 99.98% and water content of 8 ppm) under the nitrogen atmosphere at the temperature of 20 ℃, concentrating and crystallizing the filtrate to obtain a semi-finished product of lithium hexafluorophosphate, and then drying in vacuum for 24 hours at the temperature of 30 ℃ and 5mmHg to obtain the lithium hexafluorophosphate.
Comparative example 2
This comparative example is different from comparative example 1 in that the incubation time after mixing the mixed solution of the phosphorus pentafluoride triethylamine complex and the lithium fluoride mixture in step (3) is 65 minutes.
Comparative example 3
This comparative example is different from example 3 in that in step (4), after the porous lithium fluoride is mixed with the raw material liquid, the temperature is kept at 10℃for 30 minutes.
Comparative example 4
This comparative example differs from example 3 in that in step (2), the mixture of lithium hydroxide, ammonium fluoride, pore-forming agent, combustion improver and binder dispersion is directly calcined without drying to obtain porous lithium fluoride.
Performance detection test method
To characterize the formation rate of lithium hexafluorophosphate in each of examples 1 to 7 and comparative examples 1 to 3, after lithium hexafluorophosphate was obtained in examples 1 to 7 and comparative examples 1 to 3, the yield of lithium hexafluorophosphate was calculated, the calculation result of the yield is shown in Table 7, and the calculation of the yield was referred to the following formula:
TABLE 2
In order to characterize the purity of the prepared lithium hexafluorophosphate, the lithium ion content and the hexafluorophosphate content in the lithium hexafluorophosphate finished product in example 3 and examples 8 to 10 were detected by referring to GB/T19282-2003 method for analysis of lithium hexafluorophosphate product, and the purity of lithium hexafluorophosphate was calculated by taking the sum of the lithium ion content and the hexafluorophosphate content as the pure substance content of lithium hexafluorophosphate.
The detection operation steps of the hexafluorophosphate content are as follows:
(1) Weighing 0.6g of lithium hexafluorophosphate (accurate to 0.0002 g), placing a sample in a polyethylene beaker containing 20ml of ammonia-ammonium chloride solution, and uniformly stirring to obtain a sample liquid;
(2) Transferring the sample liquid into a 100ml polyethylene volumetric flask, diluting with water to a scale, transferring 10ml of the sample liquid into a polyethylene beaker, and adding 10ml of ammonia-ammonium chloride buffer solution and 30ml of water into the polyethylene beaker to obtain diluted sample liquid;
(3) Heating the diluted sample liquid in a water bath at 50 ℃ for 20min, taking out the diluted sample liquid, dropwise adding 40ml of tetraphenylarsenic chloride solution with the concentration of 0.02mol/L into the diluted sample liquid while stirring the diluted sample liquid, and standing for 40min after the dropwise adding is finished;
(4) After the completion of the standing, the mixture was dried to a constant weight (m 1 ) Carrying out suction filtration on diluted sample solution dropwise added with tetraphenylarsenicum chloride solution, flushing and suction-filtering the obtained precipitate for five times by using 50ml of ammonia water solution, and then drying the glass sand crucible and the precipitate together at the drying temperature of 110 ℃;
(5) After the glass sand crucible and the precipitate were dried to constant weight, the glass sand crucible was waited for cooling to room temperature, and then the total mass (m 2 )。
After the operation is completed, the mass fraction of hexafluorophosphate radical in the lithium hexafluorophosphate is calculated according to the following formula:
wherein m is 1 Represents the drying quality, m of the glass sand crucible 2 Represents the total mass of the precipitate and the glass sand crucible, m represents the mass of the lithium hexafluorophosphate sample, m 1 、m 2 The units of m are g.
The detection operation steps of the lithium ion content are as follows:
(1) Weighing 3g of lithium hexafluorophosphate sample by a decrement method to be accurate to 0.0002g, placing the sample in a platinum crucible, heating the sample in an electric furnace in a fume hood until white smoke disappears, then heating the sample for 10 minutes, cooling the sample, adding 10mL of hydrochloric acid solution for dissolution, transferring the sample into a 1000mL volumetric flask, diluting the sample to a scale with water, and shaking the sample uniformly to obtain solution A;
(2) Transferring the solutions in 4 100mL volumetric flasks according to Table 3, adding 5mL hydrochloric acid solution into each of the four volumetric flasks, diluting to scale with water, and shaking;
(3) An atomic absorption spectrophotometer is used for measuring the absorbance of the solution in the volumetric flask in sequence after the sensitivity of the instrument is regulated at the wavelength of 670.7nm and the water solution is zeroed;
(4) The absorbance of the blank solution is subtracted from the measured absorbance, the mass (mg) of lithium added to the lithium standard solution is taken as an abscissa, the absorbance is taken as an ordinate, a working curve is drawn, and the working curve is extrapolated to the point where the absorbance is zero, namely, the intersection point with the abscissa is the mass (mg) of lithium in the sample solution.
TABLE 3 Table 3
After the operation is completed, the mass fraction (w 2 )。
Wherein m is 4 For the mass of lithium (mg) in the test solution, which was found from the working curve, m3 is the sample mass.
Measuring mass fraction w of lithium ion 1 And mass fraction w of hexafluorophosphate ion 2 Thereafter, w is 1 And w 2 The addition represents the purity of lithium hexafluorophosphate.
The results of the lithium hexafluorophosphate purity measurements are shown in Table 4.
TABLE 4 Table 4
As can be seen in combination with examples 1-5 and comparative examples 1-2 and with Table 2, the yield of lithium hexafluorophosphate measured in comparative example 1 was close to that of examples 1-5, indicating that the yield of lithium hexafluorophosphate at a reaction time of 65min for the production of lithium hexafluorophosphate in the present application was equivalent to that measured in comparative example 1 for 4 h. The yield of lithium hexafluorophosphate measured in comparative example 2 is significantly lower than that of examples 1-5, indicating that the use of porous lithium fluoride instead of anhydrous lithium fluoride powder in the present application significantly increases the rate of formation of lithium hexafluorophosphate and shortens the time required to produce lithium hexafluorophosphate.
As can be seen from the combination of examples 1 to 5 and comparative example 3 and the combination of Table 2, the yield of lithium hexafluorophosphate measured in comparative example 3 was only about half that of examples 1 to 5, indicating that in comparative example 3, the amount of lithium hexafluorophosphate produced was small due to insufficient reaction time, and thus the measured yield was low.
As can be seen from the combination of examples 1 to 5 and comparative example 4 and the combination of table 2, comparative example 4 was not dried before preparing porous lithium fluoride, and thus the uniformity of the prepared porous lithium fluoride was poor, resulting in a decrease in the reactivity of the porous lithium fluoride, and thus the yield of lithium hexafluorophosphate measured in comparative example 4 was slightly lower than that in examples 1 to 5.
As can be seen in connection with examples 1-5 and Table 2, there is no significant change in the yield of lithium hexafluorophosphate measured in examples 1-5, indicating that varying the amounts of pore former, combustion improver, and binder dispersion in the formulation of the present application had little effect on the rate of formation of lithium hexafluorophosphate.
As can be seen from the combination of example 3 and example 6 and the combination of table 2, the triethylamine hydrogen trifluoride salt and triethylamine have better compatibility, so that the uniformity of the prepared raw material liquid is higher, the rate of formation of lithium hexafluorophosphate is increased, and the yield measured in example 6 is higher than that in example 3.
As can be seen from the combination of examples 6 and 7 and table 2, since the starch swells after absorbing the moisture in the binder dispersion, the swelled starch can increase the viscosity of the binder dispersion, thereby reducing the possibility of bleeding of the lithium fluoride mixture during the standing process, improving the uniformity of the lithium fluoride mixture, improving the pore-forming effect on the lithium fluoride mixture, and increasing the rate of formation of lithium hexafluorophosphate.
As can be seen in combination with example 3, example 8 and table 4, the purity of lithium hexafluorophosphate measured in example 8 is higher than example 3, indicating that the impurities in the porous lithium fluoride are less and the purity of lithium hexafluorophosphate is higher when the binder dispersion is formulated from gelatin and deionized water.
As can be seen from the combination of example 9 and example 8 and the combination of table 4, the inorganic salt in the straw is washed off due to the fact that the straw carbon particles are washed in the preparation process, so that impurities in the porous lithium fluoride are reduced, and the purity of the lithium hexafluorophosphate is improved.
As can be seen from the combination of example 10 and example 9 and the combination of table 4, since the straw carbon particles of the present application were washed with the sodium dodecyl sulfate solution, the tar formed during carbonization of the straw could also be washed away, thereby further reducing the impurities in the porous lithium fluoride and improving the purity of the lithium hexafluorophosphate.
The present embodiment is merely illustrative of the present application and is not intended to be limiting, and those skilled in the art, after having read the present specification, may make modifications to the present embodiment without creative contribution as required, but is protected by patent laws within the scope of the claims of the present application.
Claims (6)
1. A method for preparing lithium hexafluorophosphate, comprising the steps of:
(1) Uniformly mixing phosphorus pentachloride, triethylamine and a fluorinating agent under the protection of nitrogen, and then reacting for 3-5 hours at 5-10 ℃ to obtain a raw material liquid, wherein the fluorinating agent is used for converting the phosphorus pentachloride into phosphorus pentafluoride;
(2) Mixing 24 parts of lithium hydroxide, 37 parts of ammonium fluoride, 20-24 parts of pore-forming agent, 6-10 parts of combustion improver and 30-50 parts of binder dispersion liquid with the water content of 70-80%, uniformly stirring, and drying the mixed product to obtain a lithium fluoride mixture; in this step, the calcined product of the pore-forming agent is in a gaseous state under the reaction conditions; the pore-forming agent is starch or powdery cellulose; the adhesive dispersion liquid is prepared from an adhesive and deionized water, wherein the adhesive is sodium polyacrylate or gelatin;
(3) Calcining the lithium fluoride mixture to constant weight at 700-750 ℃ to obtain porous lithium fluoride, and cooling the porous lithium fluoride to room temperature for later use;
(4) Uniformly mixing porous lithium fluoride with raw material liquid under the protection of nitrogen, preserving heat at 5-15 ℃ for 60-80min, filtering and concentrating under reduced pressure to obtain crude lithium hexafluorophosphate, and purifying the crude lithium hexafluorophosphate to obtain lithium hexafluorophosphate;
the combustion improver in the step (2) of the preparation method of lithium hexafluorophosphate is bamboo charcoal particles or straw charcoal particles, and the straw charcoal particles are prepared according to the following steps: (1) Drying the straw at 70-85 ℃ until the water content is 0.6-1.0%, and then crushing the straw until the average particle size is 500-700 mu m to obtain straw powder; (2) Uniformly mixing straw powder with a washing liquid to obtain a straw powder dispersion liquid, heating the straw powder dispersion liquid to 280-320 ℃ in a closed environment, then preserving heat for 60-80min, and stopping heating to obtain a carbon particle dispersion liquid; (3) And carrying out suction filtration on the carbon particle dispersion liquid, and then cleaning and drying a suction filtration product to obtain straw carbon particles.
2. The method for producing lithium hexafluorophosphate according to claim 1, wherein in the step (2) of producing lithium hexafluorophosphate, 24 parts of lithium hydroxide, 37 parts of ammonium fluoride, 21-23 parts of a pore-forming agent, 7-9 parts of a combustion improver and 35-45 parts of a binder dispersion having a water content of 70-80% are mixed and stirred uniformly, and dried to obtain a lithium fluoride mixture.
3. The method for preparing lithium hexafluorophosphate according to claim 1, wherein the fluorinating agent in the step (1) is liquid hydrogen fluoride or triethylamine trihydrofluoride.
4. The method for preparing lithium hexafluorophosphate according to claim 1, wherein the washing liquid is deionized water or a surfactant solution having a water content of 80% -85%.
5. The preparation method of lithium hexafluorophosphate according to claim 1, wherein the porous lithium fluoride is prepared in a calcining device, the calcining device comprises a heating tank (1), an oven (2), a heating component (3), a mixing component (4) and a heat preservation pipe (5), the heating component (3) is used for heating the heating tank (1), the mixing component (4) is used for stirring raw materials of the porous lithium fluoride into a lithium fluoride mixture in the oven (2), the oven (2) is fixedly arranged on the heating tank (1), the oven (2) is communicated with the heating tank (1) through a feeding member (8), the feeding member (8) comprises a funnel (81) and a feeding pipe (82), one end of the funnel (81) is communicated with the oven (2), the other end of the feeding pipe (82) is communicated with the heating tank (1), one end of the feeding pipe (82) away from the funnel (81) is communicated with the heating tank (1), a valve (10) is arranged on the feeding pipe (82), two ends of the heating pipe (5) are respectively communicated with the heating tank (2), and the two ends of the heating pipe (5) are respectively wrapped around the oven (2).
6. The method for preparing lithium hexafluorophosphate according to claim 5, wherein the mixing component (4) comprises a motor (41), a rotating shaft (42), a helical blade (43) and a scraping plate (44), the motor (41) is fixedly arranged on the outer side of the oven (2), the output end of the motor (41) is coaxially connected with the rotating shaft (42), the helical blade (43) is coaxially connected with the rotating shaft (42), the rotating shaft (42) penetrates into the oven (2), and the scraping plate (44) is fixedly connected to the rotating shaft (42) and is attached to the inner side wall of the funnel (81).
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