CN116692822A - Preparation method of sodium difluorophosphate - Google Patents
Preparation method of sodium difluorophosphate Download PDFInfo
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- CN116692822A CN116692822A CN202310847643.9A CN202310847643A CN116692822A CN 116692822 A CN116692822 A CN 116692822A CN 202310847643 A CN202310847643 A CN 202310847643A CN 116692822 A CN116692822 A CN 116692822A
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- KBVUALKOHTZCGR-UHFFFAOYSA-M sodium;difluorophosphinate Chemical compound [Na+].[O-]P(F)(F)=O KBVUALKOHTZCGR-UHFFFAOYSA-M 0.000 title claims abstract description 66
- 238000002360 preparation method Methods 0.000 title claims abstract description 35
- -1 sodium hexafluorophosphate Chemical compound 0.000 claims abstract description 65
- 238000006243 chemical reaction Methods 0.000 claims abstract description 54
- 239000007788 liquid Substances 0.000 claims abstract description 49
- 239000007787 solid Substances 0.000 claims abstract description 48
- 238000000926 separation method Methods 0.000 claims abstract description 37
- 239000003960 organic solvent Substances 0.000 claims abstract description 32
- 150000002148 esters Chemical class 0.000 claims abstract description 30
- 239000000126 substance Substances 0.000 claims abstract description 19
- 238000000034 method Methods 0.000 claims abstract description 10
- 238000004519 manufacturing process Methods 0.000 claims abstract description 6
- 238000002156 mixing Methods 0.000 claims abstract description 5
- 238000001035 drying Methods 0.000 claims abstract description 4
- 238000005406 washing Methods 0.000 claims abstract description 4
- UQEAIHBTYFGYIE-UHFFFAOYSA-N hexamethyldisiloxane Chemical compound C[Si](C)(C)O[Si](C)(C)C UQEAIHBTYFGYIE-UHFFFAOYSA-N 0.000 claims description 51
- 239000007791 liquid phase Substances 0.000 claims description 43
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 29
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 claims description 24
- 239000006227 byproduct Substances 0.000 claims description 16
- 230000035484 reaction time Effects 0.000 claims description 9
- 239000012298 atmosphere Substances 0.000 claims description 8
- 230000001681 protective effect Effects 0.000 claims description 5
- 239000012670 alkaline solution Substances 0.000 claims description 3
- 239000011261 inert gas Substances 0.000 claims description 3
- 238000004821 distillation Methods 0.000 claims description 2
- 125000001153 fluoro group Chemical class F* 0.000 claims description 2
- 150000002632 lipids Chemical class 0.000 claims description 2
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 abstract description 7
- 229910001415 sodium ion Inorganic materials 0.000 abstract description 7
- 239000002000 Electrolyte additive Substances 0.000 abstract description 5
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 abstract description 2
- 229910000040 hydrogen fluoride Inorganic materials 0.000 abstract description 2
- 238000003786 synthesis reaction Methods 0.000 abstract description 2
- OBCUTHMOOONNBS-UHFFFAOYSA-N phosphorus pentafluoride Chemical compound FP(F)(F)(F)F OBCUTHMOOONNBS-UHFFFAOYSA-N 0.000 abstract 1
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 description 66
- 239000000203 mixture Substances 0.000 description 25
- 238000001914 filtration Methods 0.000 description 18
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 16
- 238000004064 recycling Methods 0.000 description 16
- 239000007789 gas Substances 0.000 description 11
- CTIKAHQFRQTTAY-UHFFFAOYSA-N fluoro(trimethyl)silane Chemical group C[Si](C)(C)F CTIKAHQFRQTTAY-UHFFFAOYSA-N 0.000 description 10
- 239000007790 solid phase Substances 0.000 description 10
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 9
- 239000011698 potassium fluoride Substances 0.000 description 9
- 239000000706 filtrate Substances 0.000 description 8
- 229910052757 nitrogen Inorganic materials 0.000 description 8
- 238000001291 vacuum drying Methods 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 6
- 239000002253 acid Substances 0.000 description 4
- 239000002994 raw material Substances 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 239000012299 nitrogen atmosphere Substances 0.000 description 2
- NROKBHXJSPEDAR-UHFFFAOYSA-M potassium fluoride Chemical compound [F-].[K+] NROKBHXJSPEDAR-UHFFFAOYSA-M 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 150000004673 fluoride salts Chemical class 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- IGILRSKEFZLPKG-UHFFFAOYSA-M lithium;difluorophosphinate Chemical compound [Li+].[O-]P(F)(F)=O IGILRSKEFZLPKG-UHFFFAOYSA-M 0.000 description 1
- 235000003270 potassium fluoride Nutrition 0.000 description 1
- 238000000634 powder X-ray diffraction Methods 0.000 description 1
- 238000001144 powder X-ray diffraction data Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/26—Phosphates
- C01B25/455—Phosphates containing halogen
-
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Inorganic Chemistry (AREA)
Abstract
The application discloses a preparation method of sodium difluorophosphate, and belongs to the technical field of chemical synthesis. The method comprises the following steps: mixing sodium hexafluorophosphate, methyl siloxane substances and an ester organic solvent for reaction, carrying out solid-liquid separation, washing the solid obtained after the solid-liquid separation, and drying to obtain sodium difluorophosphate. The method does not need hydrogen fluoride and phosphorus pentafluoride, has mild reaction conditions and low production cost, can prepare the sodium difluorophosphate with high purity and high yield, and is expected to be used as an electrolyte additive of a sodium ion battery.
Description
Technical Field
The application relates to the technical field of chemical synthesis, in particular to a preparation method of sodium difluorophosphate.
Background
Sodium difluorophosphate is promising as an electrolyte additive for sodium ion batteries. With the increase of the specific gravity of the sodium ion battery in the new energy field and the rapid development of the sodium ion power battery in the new energy automobile field, the demand prospect of sodium difluorophosphate is greatly increased.
The lithium difluorophosphate in the prior art is industrially produced in large quantities, and has certain requirements. However, hydrogen fluoride is often required for preparation, and has extremely strong acidity, high risk, high requirements on corrosion-resistant equipment and high risk for workers.
In view of this, the present application has been made.
Disclosure of Invention
The application aims to provide a preparation method of sodium difluorophosphate, which does not need strong acid, and has mild reaction conditions and low production cost.
The application can be realized as follows:
the application provides a preparation method of sodium difluorophosphate, which comprises the following steps:
mixing sodium hexafluorophosphate, methyl siloxane substances and an ester organic solvent for reaction, carrying out solid-liquid separation, washing the solid obtained after the solid-liquid separation, and drying to obtain sodium difluorophosphate.
In alternative embodiments, the reaction conditions include at least one of the following features:
characteristic one: the reaction temperature is not more than 90 ℃;
and the second characteristic is: the reaction time is not less than 4 hours;
and (3) the following characteristics: the molar ratio of the sodium hexafluorophosphate to the methyl siloxane substance to the ester organic solvent is 1:2-3:3-5;
and four characteristics: the reaction is carried out under a protective atmosphere.
In an alternative embodiment, the reaction temperature is 80-90 ℃.
In an alternative embodiment, the reaction time is from 5 to 6 hours.
In an alternative embodiment, the methylsiloxane species comprises hexamethyldisiloxane.
In an alternative embodiment, the ester-based organic solvent comprises dimethyl carbonate.
In an alternative embodiment, the molar ratio of sodium hexafluorophosphate, methyl siloxane species, and ester organic solvent is 1:2.1:4.21.
In an alternative embodiment, the protective atmosphere is an inert gas atmosphere.
In an alternative embodiment, the gaseous by-products generated during the reaction are introduced into an alkaline solution and distilled to obtain a liquid phase and a fluoride salt; standing the liquid phase, and layering to obtain methyl siloxane substances and water.
In an alternative embodiment, the liquid obtained after the solid-liquid separation is distilled to recover the lipid organic solvent.
The beneficial effects of the application include:
the sodium difluorophosphate is prepared by taking sodium hexafluorophosphate and methyl siloxane substances as raw materials and reacting in a specific ester organic solvent. The solvent and byproducts in the reaction process can be fully recycled. The preparation method does not need strong acid, has mild reaction conditions and low production cost, and the prepared sodium difluorophosphate has higher purity and yield and is expected to be used as an electrolyte additive of a sodium ion battery.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a PXRD pattern of sodium difluorophosphate prepared in example 1;
FIG. 2 is a schematic illustration of sodium difluorophosphate prepared in example 1 19 F NMR chart;
FIG. 3 is a schematic representation of sodium difluorophosphate prepared in example 1 31 P NMR chart.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the embodiments of the present application will be clearly and completely described below. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
The preparation method of sodium difluorophosphate provided by the application is specifically described below.
The application provides a preparation method of sodium difluorophosphate, which mainly comprises the following steps: mixing sodium hexafluorophosphate, methyl siloxane substances and an ester organic solvent for reaction, carrying out solid-liquid separation, washing the solid obtained after the solid-liquid separation, and drying to obtain sodium difluorophosphate.
For reference, the reaction temperature of the sodium hexafluorophosphate, the methylsiloxane compound and the ester organic solvent does not exceed 90 ℃, and may be 90 ℃, 85 ℃,80 ℃, 75 ℃, 70 ℃, 65 ℃ or the like.
If the reaction temperature is higher than 90 ℃, the boiling point of part of the ester organic solvent is exceeded, which is unfavorable for the safety of the reaction.
In some preferred embodiments, the reaction temperature of the sodium hexafluorophosphate, the methylsiloxane species and the ester organic solvent is 80-90 ℃, such as 80 ℃, 81 ℃, 82 ℃, 83 ℃, 84 ℃, 85 ℃, 86 ℃, 87 ℃, 88 ℃, 89 ℃, or 90 ℃, etc., but may also be any other value in the range of 80-90 ℃.
The reaction time of the sodium hexafluorophosphate, the methyl siloxane substance and the ester organic solvent is not less than 4 hours, such as 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours or 8 hours, and the like, and can be other values within the range of not less than 4 hours.
If the reaction time is shorter than 4 hours, the reaction is unfavorable to completion, resulting in a decrease in yield.
In some preferred embodiments, the reaction time may be 5-6 hours, such as 5 hours, 5.5 hours, or 6 hours, and the like, and may be any other value within the range of 5-6 hours.
For reference, the molar ratio of sodium hexafluorophosphate, methylsiloxane species, and ester organic solvent may be 1:2-3:3-5, such as 1:2:3, 1:2:3.5, 1:2:4, 1:2:4.5, 1:2:5, 1:2.5:3, 1:2.5:3.5, 1:2.5:4, 1:2.5:4.5, 1:2.5:5, 1:3:3, 1:3:3.5, 1:3:4, 1:3:4.5, or 1:3:5, etc., and may be any other value within the range of 1:2-3:3-5.
If the molar ratio of sodium hexafluorophosphate to methyl siloxane is less than 1:2 (such as 1:1.5), incomplete reaction is easily caused; if the molar ratio of sodium hexafluorophosphate to methyl siloxane is greater than 1:3 (e.g., 1:3.5), the reaction is likely to be inhibited from proceeding due to excessive amounts of reactants. If the molar ratio of the sodium hexafluorophosphate to the ester organic solvent is less than 1:3 (such as 1:2.5), incomplete dissolution is easily caused, and the yield is reduced; if the molar ratio of the sodium hexafluorophosphate to the ester organic solvent is more than 1:5 (such as 1:5.5), the system is easily oversized, and the reaction time is prolonged.
In some embodiments, the molar ratio of sodium hexafluorophosphate, methyl siloxane species, and ester organic solvent is 1:2.1:4.21.
The above reaction is carried out under a protective atmosphere, which is illustratively a nitrogen atmosphere or an inert gas atmosphere, preferably a nitrogen atmosphere.
For reference, the methylsiloxanes may be hexamethyldisiloxane, and the ester organic solvent may be dimethyl carbonate.
In some embodiments, the sodium difluorophosphate is prepared by a process comprising: sodium hexafluorophosphate, hexamethyldisiloxane and dimethyl carbonate are mixed according to the molar ratio of 1:2.1:4.21, and reacting at 90 ℃ for 6 hours under the protection of nitrogen.
The reaction equation involved in this process includes:
in some embodiments, after the reaction of sodium hexafluorophosphate, methyl siloxane substances and ester organic solvents, the solid obtained by solid-liquid separation is mixed with ethyl acetate, and then filtered, distilled and dried to obtain the target product sodium difluorophosphate with high purity.
By mixing the solid phase with ethyl acetate, the ethyl acetate can dissolve impurities, but sodium difluorophosphate cannot be dissolved in the ethyl acetate, and the solid obtained by filtration is dried, so that the sodium difluorophosphate with high purity is obtained. And distilling the liquid obtained by filtering to obtain ethyl acetate, wherein the ethyl acetate can be recycled.
In addition, after the reaction of sodium hexafluorophosphate, methyl siloxane substance and ester organic solvent, the liquid obtained by solid-liquid separation can be distilled to recover the ester organic solvent.
In the solid-liquid separation process, the sodium difluorophosphate is a solid phase (white solid) which is not mixed with a liquid phase, the liquid phase is an ester organic solvent, and the liquid phase is distilled to obtain the ester organic solvent, and the ester organic solvent can be recycled.
In the reaction process of sodium hexafluorophosphate, methyl siloxane substances and ester organic solvents, gas byproducts are generated, and in some embodiments, the gas byproducts generated in the reaction process can be introduced into an alkaline solution for distillation to obtain a liquid phase and fluorine salt; and standing the liquid phase, and layering to obtain the methyl siloxane substance and water.
Taking sodium hexafluorophosphate, hexamethyldisiloxane and dimethyl carbonate as an example, in the reaction process, the generated gas byproduct is trimethylfluorosilane, and the trimethylfluorosilane is introduced into a potassium hydroxide solution and distilled to obtain a mixture (liquid phase) of hexamethyldisiloxane and water and potassium fluoride (solid residue); standing the liquid phase, layering, wherein the upper layer is hexamethyldisiloxane, and the lower layer is water. The obtained hexamethyldisiloxane can be recycled.
On the premise of bearing, the sodium difluorophosphate is prepared by taking sodium hexafluorophosphate and methyl siloxane substances as raw materials and reacting in a specific ester organic solvent at the reaction temperature of not more than 90 ℃, and the solvent and byproducts in the reaction process can be fully recycled. The preparation method does not need strong acid, has mild reaction conditions and low production cost, and the prepared sodium difluorophosphate has higher purity (not lower than 97%) and yield (not lower than 86%) and is expected to be used as an electrolyte additive of a sodium ion battery.
The features and capabilities of the present application are described in further detail below in connection with the examples.
Example 1
The embodiment provides a preparation method of sodium difluorophosphate, which comprises the following steps:
sodium hexafluorophosphate, hexamethyldisiloxane and dimethyl carbonate are mixed according to the molar ratio of 1:2.1:4.21, and reacting for 6 hours under the condition of 90 ℃ under the protection of nitrogen.
After the reaction, the mixture was cooled to room temperature, and then solid-liquid separation was performed.
And (3) distilling the liquid phase obtained by solid-liquid separation, and recovering to obtain dimethyl carbonate (for recycling).
The solid phase (sodium difluorophosphate white solid) obtained by solid-liquid separation was washed with ethyl acetate, concentrated, and filtered to obtain a filtrate and a solid. The solid obtained by filtration is dried in a vacuum drying oven at 80 ℃ to obtain sodium difluorophosphate. The liquid obtained by filtration is distilled to obtain ethyl acetate (which can be recycled).
And (3) introducing a gas byproduct (trimethylfluorosilane) generated in the reaction process into a potassium hydroxide solution, and distilling to obtain a liquid phase and a solid residue. Wherein the solid residue is KF, and the liquid phase is a mixture of hexamethyldisiloxane and water. And (3) standing and layering a liquid phase (a mixture of hexamethyldisiloxane and water), wherein the upper layer is hexamethyldisiloxane, the lower layer is water, and the hexamethyldisiloxane is used for recycling.
The yield of the sodium difluorophosphate prepared by the preparation method is 96% and the purity is 98%. The PXRD diagram of the sodium difluorophosphate, 19 F NMR chart 31 The P NMR charts are shown in fig. 1 to 3 in this order. F1 on the abscissa in fig. 2 and 3 represents the chemical shift.
Example 2
The embodiment provides a preparation method of sodium difluorophosphate, which comprises the following steps:
sodium hexafluorophosphate, hexamethyldisiloxane and dimethyl carbonate are mixed according to the molar ratio of 1:2.1:3, and reacting for 6h under the condition of 90 ℃ under the protection of nitrogen.
After the reaction, the mixture was cooled to room temperature, and then solid-liquid separation was performed.
And (3) distilling the liquid phase obtained by solid-liquid separation, and recovering to obtain dimethyl carbonate (for recycling).
The solid phase (sodium difluorophosphate white solid) obtained by solid-liquid separation was washed with ethyl acetate, concentrated, and filtered to obtain a filtrate and a solid. The solid obtained by filtration is dried in a vacuum drying oven at 80 ℃ to obtain sodium difluorophosphate. The liquid obtained by filtration is distilled to obtain ethyl acetate (which can be recycled).
And (3) introducing a gas byproduct (trimethylfluorosilane) generated in the reaction process into a potassium hydroxide solution, and distilling to obtain a liquid phase and a solid residue. Wherein the solid residue is KF, and the liquid phase is a mixture of hexamethyldisiloxane and water. And (3) standing and layering a liquid phase (a mixture of hexamethyldisiloxane and water), wherein the upper layer is hexamethyldisiloxane, the lower layer is water, and the hexamethyldisiloxane is used for recycling.
The yield of the sodium difluorophosphate prepared by the preparation method is 90% and the purity is 98%.
Example 3
The embodiment provides a preparation method of sodium difluorophosphate, which comprises the following steps:
sodium hexafluorophosphate, hexamethyldisiloxane and dimethyl carbonate are mixed according to the molar ratio of 1:2.1:5, and reacting for 6 hours under the condition of 90 ℃ under the protection of nitrogen.
After the reaction, the mixture was cooled to room temperature, and then solid-liquid separation was performed.
And (3) distilling the liquid phase obtained by solid-liquid separation, and recovering to obtain dimethyl carbonate (for recycling).
The solid phase (sodium difluorophosphate white solid) obtained by solid-liquid separation was washed with ethyl acetate, concentrated, and filtered to obtain a filtrate and a solid. The solid obtained by filtration is dried in a vacuum drying oven at 80 ℃ to obtain sodium difluorophosphate. The liquid obtained by filtration is distilled to obtain ethyl acetate (which can be recycled).
And (3) introducing a gas byproduct (trimethylfluorosilane) generated in the reaction process into a potassium hydroxide solution, and distilling to obtain a liquid phase and a solid residue. Wherein the solid residue is KF, and the liquid phase is a mixture of hexamethyldisiloxane and water. And (3) standing and layering a liquid phase (a mixture of hexamethyldisiloxane and water), wherein the upper layer is hexamethyldisiloxane, the lower layer is water, and the hexamethyldisiloxane is used for recycling.
The yield of the sodium difluorophosphate prepared by the preparation method is 93 percent and the purity is 98 percent.
Example 4
The embodiment provides a preparation method of sodium difluorophosphate, which comprises the following steps:
sodium hexafluorophosphate, hexamethyldisiloxane and dimethyl carbonate are mixed according to the molar ratio of 1:3:3, and reacting for 6h under the condition of 90 ℃ under the protection of nitrogen.
After the reaction, the mixture was cooled to room temperature, and then solid-liquid separation was performed.
And (3) distilling the liquid phase obtained by solid-liquid separation, and recovering to obtain dimethyl carbonate (for recycling).
The solid phase (sodium difluorophosphate white solid) obtained by solid-liquid separation was washed with ethyl acetate, concentrated, and filtered to obtain a filtrate and a solid. The solid obtained by filtration is dried in a vacuum drying oven at 80 ℃ to obtain sodium difluorophosphate. The liquid obtained by filtration is distilled to obtain ethyl acetate (which can be recycled).
And (3) introducing a gas byproduct (trimethylfluorosilane) generated in the reaction process into a potassium hydroxide solution, and distilling to obtain a liquid phase and a solid residue. Wherein the solid residue is KF, and the liquid phase is a mixture of hexamethyldisiloxane and water. And (3) standing and layering a liquid phase (a mixture of hexamethyldisiloxane and water), wherein the upper layer is hexamethyldisiloxane, the lower layer is water, and the hexamethyldisiloxane is used for recycling.
The yield of the sodium difluorophosphate prepared by the preparation method is 92% and the purity is 97%.
Example 5
The embodiment provides a preparation method of sodium difluorophosphate, which comprises the following steps:
sodium hexafluorophosphate, hexamethyldisiloxane and dimethyl carbonate are mixed according to the molar ratio of 1:3:5, and reacting for 6 hours under the condition of 90 ℃ under the protection of nitrogen.
After the reaction, the mixture was cooled to room temperature, and then solid-liquid separation was performed.
And (3) distilling the liquid phase obtained by solid-liquid separation, and recovering to obtain dimethyl carbonate (for recycling).
The solid phase (sodium difluorophosphate white solid) obtained by solid-liquid separation was washed with ethyl acetate, concentrated, and filtered to obtain a filtrate and a solid. The solid obtained by filtration is dried in a vacuum drying oven at 80 ℃ to obtain sodium difluorophosphate. The liquid obtained by filtration is distilled to obtain ethyl acetate (which can be recycled).
And (3) introducing a gas byproduct (trimethylfluorosilane) generated in the reaction process into a potassium hydroxide solution, and distilling to obtain a liquid phase and a solid residue. Wherein the solid residue is KF, and the liquid phase is a mixture of hexamethyldisiloxane and water. And (3) standing and layering a liquid phase (a mixture of hexamethyldisiloxane and water), wherein the upper layer is hexamethyldisiloxane, the lower layer is water, and the hexamethyldisiloxane is used for recycling.
The yield of the sodium difluorophosphate prepared by the preparation method is 93 percent and the purity is 98 percent.
Example 6
The embodiment provides a preparation method of sodium difluorophosphate, which comprises the following steps:
sodium hexafluorophosphate, hexamethyldisiloxane and dimethyl carbonate are mixed according to the molar ratio of 1:2.1:4.21, and reacting for 6 hours under the condition of 80 ℃ under the protection of nitrogen.
After the reaction, the mixture was cooled to room temperature, and then solid-liquid separation was performed.
And (3) distilling the liquid phase obtained by solid-liquid separation, and recovering to obtain dimethyl carbonate (for recycling).
The solid phase (sodium difluorophosphate white solid) obtained by solid-liquid separation was washed with ethyl acetate, concentrated, and filtered to obtain a filtrate and a solid. The solid obtained by filtration is dried in a vacuum drying oven at 80 ℃ to obtain sodium difluorophosphate. The liquid obtained by filtration is distilled to obtain ethyl acetate (which can be recycled).
And (3) introducing a gas byproduct (trimethylfluorosilane) generated in the reaction process into a potassium hydroxide solution, and distilling to obtain a liquid phase and a solid residue. Wherein the solid residue is KF, and the liquid phase is a mixture of hexamethyldisiloxane and water. And (3) standing and layering a liquid phase (a mixture of hexamethyldisiloxane and water), wherein the upper layer is hexamethyldisiloxane, the lower layer is water, and the hexamethyldisiloxane is used for recycling.
The yield of the sodium difluorophosphate prepared by the preparation method is 87% and the purity is 98%.
Example 7
The embodiment provides a preparation method of sodium difluorophosphate, which comprises the following steps:
sodium hexafluorophosphate, hexamethyldisiloxane and dimethyl carbonate are mixed according to the molar ratio of 1:2.1:4.21, and reacting for 5h under the condition of 85 ℃ under the protection of nitrogen.
After the reaction, the mixture was cooled to room temperature, and then solid-liquid separation was performed.
And (3) distilling the liquid phase obtained by solid-liquid separation, and recovering to obtain dimethyl carbonate (for recycling).
The solid phase (sodium difluorophosphate white solid) obtained by solid-liquid separation was washed with ethyl acetate, concentrated, and filtered to obtain a filtrate and a solid. The solid obtained by filtration is dried in a vacuum drying oven at 80 ℃ to obtain sodium difluorophosphate. The liquid obtained by filtration is distilled to obtain ethyl acetate (which can be recycled).
And (3) introducing a gas byproduct (trimethylfluorosilane) generated in the reaction process into a potassium hydroxide solution, and distilling to obtain a liquid phase and a solid residue. Wherein the solid residue is KF, and the liquid phase is a mixture of hexamethyldisiloxane and water. And (3) standing and layering a liquid phase (a mixture of hexamethyldisiloxane and water), wherein the upper layer is hexamethyldisiloxane, the lower layer is water, and the hexamethyldisiloxane is used for recycling.
The yield of the sodium difluorophosphate prepared by the preparation method is 86% and the purity is 97%.
Example 8
The embodiment provides a preparation method of sodium difluorophosphate, which comprises the following steps:
sodium hexafluorophosphate, hexamethyldisiloxane and dimethyl carbonate are mixed according to the molar ratio of 1:2.1:4.21, and reacting for 6 hours under the protection of argon at 90 ℃.
After the reaction, the mixture was cooled to room temperature, and then solid-liquid separation was performed.
And (3) distilling the liquid phase obtained by solid-liquid separation, and recovering to obtain dimethyl carbonate (for recycling).
The solid phase (sodium difluorophosphate white solid) obtained by solid-liquid separation was washed with ethyl acetate, concentrated, and filtered to obtain a filtrate and a solid. The solid obtained by filtration is dried in a vacuum drying oven at 80 ℃ to obtain sodium difluorophosphate. The liquid obtained by filtration is distilled to obtain ethyl acetate (which can be recycled).
And (3) introducing a gas byproduct (trimethylfluorosilane) generated in the reaction process into a potassium hydroxide solution, and distilling to obtain a liquid phase and a solid residue. Wherein the solid residue is KF, and the liquid phase is a mixture of hexamethyldisiloxane and water. And (3) standing and layering a liquid phase (a mixture of hexamethyldisiloxane and water), wherein the upper layer is hexamethyldisiloxane, the lower layer is water, and the hexamethyldisiloxane is used for recycling.
The yield of the sodium difluorophosphate prepared by the preparation method is 93 percent and the purity is 98 percent.
Comparative example 1
The difference between this comparative example and example 1 is that: the reaction time of sodium hexafluorophosphate, hexamethyldisiloxane and dimethyl carbonate was 3h.
The yield of the sodium difluorophosphate prepared by the preparation method is 71% and the purity is 95%.
Comparative example 2
The difference between this comparative example and example 1 is that: sodium hexafluorophosphate, hexamethyldisiloxane and dimethyl carbonate in a molar ratio of 1:2.1:6.
the yield of the sodium difluorophosphate prepared by the preparation method is 65% and the purity is 94%.
Comparative example 3
The difference between this comparative example and example 1 is that: sodium hexafluorophosphate, hexamethyldisiloxane and dimethyl carbonate in a molar ratio of 1:1.5:4.21.
the yield of the sodium difluorophosphate prepared by the preparation method is 67% and the purity is 96%.
In summary, the sodium difluorophosphate is prepared by taking sodium hexafluorophosphate and methyl siloxane substances as raw materials and reacting in a specific ester organic solvent at the reaction temperature of not more than 90 ℃, and the solvent and byproducts in the reaction process can be fully recycled. The preparation method does not need strong acid, has mild reaction conditions and low production cost, and the molar ratio of the sodium hexafluorophosphate, the methyl siloxane substances and the ester organic solvent is within the range of 1:2-3:3-5, so that the prepared sodium difluorophosphate has higher purity (not lower than 97%) and yield (not lower than 86%), and is expected to be used as an electrolyte additive of a sodium ion battery.
The above is only a preferred embodiment of the present application, and is not intended to limit the present application, but various modifications and variations can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.
Claims (10)
1. A method for preparing sodium difluorophosphate, comprising the steps of:
mixing sodium hexafluorophosphate, methyl siloxane substances and an ester organic solvent for reaction, carrying out solid-liquid separation, washing the solid obtained after the solid-liquid separation, and drying to obtain sodium difluorophosphate.
2. The method of claim 1, wherein the reaction conditions include at least one of the following characteristics:
characteristic one: the reaction temperature is not more than 90 ℃;
and the second characteristic is: the reaction time is not less than 4 hours;
and (3) the following characteristics: the molar ratio of the sodium hexafluorophosphate to the methyl siloxane substance to the ester organic solvent is 1:2-3:3-5;
and four characteristics: the reaction is carried out under a protective atmosphere.
3. The preparation process according to claim 1 or 2, wherein the reaction temperature is 80-90 ℃.
4. The preparation method according to claim 1 or 2, wherein the reaction time is 5 to 6 hours.
5. The method of preparation according to claim 1 or 2, wherein the methylsiloxanes comprise hexamethyldisiloxane.
6. The production method according to claim 1 or 2, wherein the ester-based organic solvent comprises dimethyl carbonate.
7. The preparation method according to claim 1 or 2, wherein the molar ratio of the sodium hexafluorophosphate, the methylsiloxane-based substance and the ester-based organic solvent is 1:2.1:4.21.
8. The method according to claim 2, wherein the protective atmosphere is an inert gas atmosphere.
9. The method according to claim 1, wherein the gaseous by-product produced during the reaction is introduced into an alkaline solution and distilled to obtain a liquid phase and a fluorine salt; and standing the liquid phase, and layering to obtain the methyl siloxane substance and water.
10. The process according to claim 1, wherein the lipid organic solvent is recovered by subjecting the liquid obtained after the solid-liquid separation to distillation treatment.
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