SYNTHESIS METHOD OF HEXAFLUOROPHOSPHATE

Abstract

The disclosure discloses a synthesis method of hexafluorophosphate, belonging to the technical field of chemical synthesis. The synthesis method of hexafluorophosphate is characterized by comprising the following steps: reacting a phosphorus pentahalide inert solvent solution obtained by dissolving phosphorus pentahalide into an inert solvent with an alkali metal fluoride salt hydrogen fluoride solution obtained by dissolving an alkali metal halide salt into anhydrous hydrogen fluoride in a reactor in a ratio to obtain a mixture consisting of hexafluorophosphate, hydrogen fluoride, the inert solvent and hydrogen halide, performing gas-liquid separation to remove a hydrogen halide gas, then heating and evaporating to recover hydrogen fluoride, finally performing solid-liquid separation to recover the inert solvent, and then drying the solid to obtain hexafluorophosphate. The synthesis method of the disclosure has the advantages of simple operation, good safety, high reaction yield, excellent product quality and the like, and can achieve continuous production.

Claims

1. A synthesis method of hexafluorophosphate, comprising the following steps: (1) dissolving phosphorus pentahalide into an inert solvent to obtain a phosphorus pentahalide inert solvent solution; (2) dissolving an alkali metal halide salt into anhydrous hydrogen fluoride to obtain an alkali metal fluoride salt hydrogen fluoride solution; (3) reacting the phosphorus pentahalide inert solvent solution with the alkali metal fluoride salt hydrogen fluoride solution in a reactor in a ratio to obtain a mixture consisting of hexafluorophosphate, hydrogen fluoride, the inert solvent and hydrogen halide; wherein, instep (3), a feeding ratio of the phosphorus pentahalide inert solvent solution to the alkali metal fluoride salt hydrogen fluoride solution in the reactor is as follows: a molar ratio of phosphorus contained in the phosphorus pentahalide inert solvent solution entering the reactor within unit time to alkali metal contained in the alkali metal fluoride salt hydrogen fluoride solution entering the reactor within unit time is 0.8-1.2:1; in step (3), the reaction temperature is −40 to 100° C.; (4) performing gas-liquid separation on the mixture consisting of hexafluorophosphate, hydrogen fluoride, the inert solvent and hydrogen halide obtained in step (3) to separate out a hydrogen halide gas, so as to obtain a mixture consisting of hexafluorophosphate, hydrogen fluoride and the inert solvent; (5) removing hydrogen fluoride from the mixture consisting of hexafluorophosphate, hydrogen fluoride and the inert solvent obtained in step (4) to obtain a mixture consisting of hexafluorophosphate and the inert solvent; and (6) performing solid-liquid separation on the mixture consisting of hexafluorophosphate and the inert solvent obtained in step (5), and then drying to obtain hexafluorophosphate.

2. The synthesis method of hexafluorophosphate according to claim 1, wherein the hexafluorophosphate is any one of lithium hexafluorophosphate, sodium hexafluorophosphate and potassium hexafluorophosphate.

3. The synthesis method of hexafluorophosphate according to claim 1, wherein in step (1), the phosphorus pentahalide is selected from one or two of phosphorus pentachloride and phosphorus pentabromide.

4. The synthesis method of hexafluorophosphate according to claim 1, wherein in step (1), the inert solvent is selected from one or more of: alkane solvents selected from C4-C10 straight, branched or cyclic alkanes; halogenated alkane solvents represented by the following general formula:
C.sub.nH.sub.(2n+2−m)X.sub.m wherein X=F, Cl and Br, n=1-10, m=1-4, the carbon chain of halogenated alkane is straight, branched or cyclic; aromatic solvents represented by the following general formula: R.sub.n ##STR00007## wherein substituent group R is H, or a C1-C6 straight, branched or cyclic alkyl substituent group, n=0-6, when multiple alkyl substituent groups are present in a phenyl ring, the alkyl substituent groups are the same or different; halogenated aromatic solvents represented by the following general formula:
R.sub.n X.sub.m ##STR00008## wherein substituent group R is H, or a C1-C6 straight, branched or cyclic alkyl substituent group, n=0-6, substituent group X=F, Cl and Br, m=0-6 and n+m≤6, when multiple alkyl and halogen atom substitutions are present in the phenyl ring, substituted alkyl and halogen atoms are the same or different.

5. The synthesis method of hexafluorophosphate according to claim 1, wherein in step (1), the amount of the inert solvent is as 1-20 times as the mass of phosphorus pentahalide.

6. The synthesis method of hexafluorophosphate according to claim 1, wherein in step (2), the alkali metal halide salt is represented by the following general formula:
MX
M=Li, Na and K
X=F, Cl and Br

7. The synthesis method of hexafluorophosphate according to claim 1, wherein in step (2), the amount of hydrogen fluoride is as 1-20 times as the mass of the alkali metal halide salt.

8. The synthesis method of hexafluorophosphate according to claim 1, wherein in step (2), the operation temperature for dissolving the alkali metal halide salt into anhydrous hydrogen fluoride to obtain the alkali metal fluoride salt hydrogen fluoride solution and the preservation temperature of the alkali metal fluoride salt hydrogen fluoride solution are −40 to 19° C.

9. The synthesis method of hexafluorophosphate according to claim 1, wherein when the synthesized product is lithium hexafluorophosphate, the alkali metal halide salt is selected from one or more of lithium fluoride, lithium chloride and lithium bromide; when the synthesized product is sodium hexafluorophosphate, the alkali metal halide salt is selected from one or more of sodium fluoride, sodium chloride and sodium bromide; when the synthesized product is potassium hexafluorophosphate, the alkali metal halide salt is selected from one or more of potassium fluoride, potassium chloride and potassium bromide.

10. The synthesis method of hexafluorophosphate according to claim 1, wherein in step (3), the reactor is a microreactor.

11. The synthesis method of hexafluorophosphate according to claim 1, wherein in step (3), the feeding ratio of the phosphorus pentahalide inert solvent solution to the alkali metal fluoride salt hydrogen fluoride solution in the reactor is as follows: the molar ratio of phosphorus contained in the phosphorus pentahalide inert solvent solution entering the reactor within unit time to alkali metal contained in the alkali metal fluoride salt hydrogen fluoride solution entering the reactor within unit time is 0.8-1.2:1.

12. The synthesis method of hexafluorophosphate according to claim 1, wherein in step (3), the reaction temperature is −40 to 100° C.

13. The synthesis method of hexafluorophosphate according to claim 1, wherein in step (4), the operation temperature for gas-liquid separation is −40 to 19° C.

14. The synthesis method of hexafluorophosphate according to claim 1, wherein in step (5), the operation temperature for removing hydrogen fluoride is 20-100° C.

Description

DESCRIPTION OF THE DRAWINGS

[0076] FIG. 1 is a schematic diagram of a continuous synthesis flow process of hexafluorophosphate in the disclosure, which includes “kettle continuous-continuous flow-kettle continuous”.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0077] In combination with FIG. 1, the disclosure adopts the continuous reaction process “kettle continuous-continuous flow-kettle continuous” to synthesize lithium hexafluorophosphate. The specific flow process is as follows:

[0078] (1) preparation of a phosphorus pentahalide inert solvent solution adopts an AB two-line system, wherein the AB two lines operate in a cross manner. When a phosphorus pentahalide solution is prepared for the A line, the phosphorus pentahalide solution is fed for the B line. Conversely, when the phosphorus pentahalide solution is prepared for the B line, the phosphorus pentahalide solution is fed for the A line. As such, the continuous feeding of the phosphorus pentahalide inert solvent solution can be achieved.

[0079] (2) Preparation of an alkali metal fluoride salt hydrogen fluoride solution adopts an AB two-line system, wherein the AB two lines operate in a cross manner. When an alkali metal fluoride salt solution is prepared for the A line, the alkali metal fluoride salt solution is fed for the B line. Conversely, when the alkali metal fluoride salt solution is prepared for the B line, the alkali metal fluoride salt solution is fed for the A line. As such, the continuous feeding of the alkali metal fluoride salt hydrogen fluoride solution can be achieved; when the alkali metal fluoride salt uses an alkali metal chloride salt or an alkali metal bromide salt, the generated hydrogen halide gas enters a hydrogen halide treatment system.

[0080] (3) The phosphorus pentahalide inert solvent solution and the alkali metal fluoride salt hydrogen fluoride solution are input into a continuous-flow reactor for reaction in a ratio via a metering pump, parameter setting and adjustment are performed on a feeding ratio, a feeding speed, a reaction temperature, a retention time and the like according to process requirements, and continuous reaction, continuous feeding and continuous discharge are achieved.

[0081] (4) The mixture (III) at the outlet of the continuous-flow reactor is subjected to continuous gas-liquid separation to remove hydrogen halide to obtain the mixture (IV), the removed hydrogen halide gas enters the hydrogen halide treatment system.

[0082] (5) The mixture (IV) was subjected to collection and removal of hydrogen fluoride to obtain the mixture (V), the mixture (V) is subjected to solid-liquid separation to obtain hexafluorophosphate, the above operations adopt an AB two-line system, the AB two lines operate in a cross manner, when the mixture (IV) is collected for the A line, hydrogen fluoride is removed from the mixture (IV) for the B line to obtain the mixture (V), the mixture (V) is subjected to solid-liquid separation to obtain hexafluorophosphate; when the mixture (IV) is collected for the B line, hydrogen fluoride is removed from the mixture (IV) for the A line to obtain the mixture (V), the mixture (V) is subjected to solid-liquid separation to obtain hexafluorophosphate. As such, on one hand, a continuous gas-liquid separator is seamlessly connected, and on the other hand, continuous hydrogen fluoride removal and solid-liquid separation operations can be achieved so as to ensure the continuous and stable operation of the synthesis process; the removed hydrogen fluoride enters the hydrogen fluoride recovery system, and the inert solvent obtained from solid-liquid separation returns back to the preparation process of the phosphorus pentahalide inert solvent solution.

[0083] (6) Hexafluorophosphate is dried to obtain a hexafluorophosphate finished product, and the package process of the hexafluorophosphate finished product is carried out in a single line, continuous drying and continuous package devices are rationally matched according to actual capacity, thereby achieving the continuous drying and continuous packaging operations of hexafluorophosphate.

Example 1

[0084] Lithium hexafluorophosphate was synthesized by using a microreactor as a continuous reactor, phosphorus pentachloride, lithium chloride and hydrogen fluoride as raw materials and toluene as an inert organic solvent. By combining with a process flowchart 1, the synthesis process was as follows:

[0085] (1) quantitative toluene was added into a phosphorus pentachloride toluene solution preparation kettle, a quantitative phosphorus pentachloride solid was added under the protection of nitrogen, the temperature was raised to 60-65° C. under the condition of stirring, and the temperature was reduced to 20-25° C. after the solid was completely dissolved, so as to obtain a phosphorus pentachloride toluene solution with a mass concentration of 25%, which was stored for later use under the protection of nitrogen. The phosphorus pentachloride toluene solution preparation kettle was divided into AB kettles which were used interchangeably.

[0086] (2) A quantitative anhydrous hydrogen fluoride liquid was added to a lithium fluoride hydrogen fluoride solution preparation kettle, the temperature was controlled at −10 to −5° C. under the protection of nitrogen, and then a quantitative lithium chloride solid was slowly added in batch and dissolved under the condition of stirring, so as to obtain a lithium fluoride hydrogen fluoride solution with a mass concentration of 20%, which was stored for later use at −10 to −5° C. under the protection of nitrogen; the hydrogen chloride gas generated in the preparation process entered a hydrogen chloride treatment system. The lithium fluoride hydrogen fluoride solution preparation kettle was divided into AB kettles which were used interchangeably.

[0087] (3) The phosphorus pentachloride toluene solution was continuously input into the microreactor at the speed of 500 g/min via a metering pump, the lithium fluoride hydrogen fluoride solution was continuously input into the microreactor at the speed of 77.85 g/min via the metering pump, the two materials were sufficiently mixed at the inlet of the microreactor and then reacted in the microreactor, the microreactor adopted step temperature control, wherein the maximum temperature in the middle of the microreactor was controlled at 60-65° C., and the temperature of the outlet of the microreactor was controlled at −15 to −10° C., and the materials stayed for about 80 seconds in the microreactor.

[0088] (4) The reaction solution flew out of the microreactor and then entered a continuous gas-liquid separator, wherein the temperature of the gas-liquid separator was controlled at −15 to −10° C., the gas separated from the gas-liquid separator entered the hydrogen chloride treatment system, the liquid separated from the gas-liquid separator entered a collection kettle, wherein the temperature of the collection kettle was controlled at 0-5° C. The collection kettle was divided into AB kettles which were used interchangeably.

[0089] (5) After the material in the collection kettle was completely collected, the temperature of the collection kettle was slowly raised to 40-45° C. so that hydrogen fluoride was removed by evaporation, the hydrogen fluoride steam entered a hydrogen fluoride recovery system, dry nitrogen was introduced after most of the hydrogen fluoride was removed to purge the materials for 2 hours at 40-45° C., the temperature of the collection kettle was reduced to 5-10° C. after purging was ended, then a lithium hexafluorophosphate wet solid was obtained by centrifugation, and centrifuge mother liquor was used as recovered toluene to return back to a toluene groove of a phosphorus pentachloride toluene solution preparation process.

[0090] (6) The lithium hexafluorophosphate wet solid entered a single-cone spiral belt dryer via a solid material delivery system to be dried at reduced pressure, and then packaged through an automatic passage machine after being qualified via detection.

[0091] The hydrogen chloride treatment system: the hydrogen chloride treatment system consists of a three-stage tandem condenser, a two-stage defluorination packing tower, a three-stage falling film absorber and a two-stage alkali spraying tower. In the three-stage tandem condenser, a −35 to −30° C. frozen liquid was introduced, and hydrogen fluoride entrained in hydrogen chloride was condensed and recovered; in the two-stage defluorination packing tower, a hydrogen fluoride adsorption filler was loaded in the tower to remove a small amount of residual hydrogen fluoride in hydrogen chloride subjected to condensation and defluorination; high-pure hydrogen chloride obtained by defluorination treatment was absorbed with water in the three-stage falling film absorber to obtain a hydrogen chloride solution with a concentration of 35-36%; after being deacidified by secondary alkali spraying, the tail gas met the standard to be discharged.

[0092] The hydrogen fluoride recovery system: the hydrogen fluoride recovery system consists of a three-stage tandem condenser, a three-stage falling film absorber, and a two-stage alkali spraying tower. In the three-stage tandem condenser, a −35 to −30° C. frozen liquid was introduced, most of the hydrogen fluoride was condensed and recovered; hydrogen fluoride left in the tail gas was absorbed with water in the three-stage falling film absorber to obtain a hydrofluoric acid solution with a concentration of 49±0.2%; after being deacidified by secondary alkali spraying, the tail gas met the standard to be discharged.

[0093] The synthesis of lithium hexafluorophosphate in this example spent 10 hours from starting feeding to stable debugging. Starting from the completion of debugging, timing was started and stable operation was carried out for 300 hours. The results are summarized as follows: a total of 2250 kg of phosphorus pentachloride and 458 kg of lithium chloride were consumed, resulting in 1630 kg of lithium hexafluorophosphate finished product with a yield of 99.3% and a purity of 99.85%.

Example 2

[0094] Sodium hexafluorophosphate was synthesized by using a microreactor as a continuous reactor, phosphorus pentachloride, sodium fluoride and hydrogen fluoride as raw materials and chlorobenzene as an inert organic solvent. By combining with a process flowchart 1, the synthesis process was as follows:

[0095] (1) quantitative chlorobenzene was added into a phosphorus pentachloride chlorobenzene solution preparation kettle, a quantitative phosphorus pentachloride solids was added under the protection of nitrogen, the temperature was raised to 50-55° C. under the condition of stirring, and the temperature was reduced to 10-15° C. after the solid was completely dissolved, so as to obtain a phosphorus pentachloride chlorobenzene solution with a mass concentration of 20%, which was stored for later use under the protection of nitrogen. The phosphorus pentachloride chlorobenzene solution preparation kettle was divided into AB kettles which were used interchangeably.

[0096] (2) A quantitative anhydrous hydrogen fluoride liquid was added to a sodium fluoride hydrogen fluoride solution preparation kettle, the temperature was controlled at 10-15° C. under the protection of nitrogen, and then a quantitative sodium chloride solid was slowly added in batch and dissolved under the condition of stirring, so as to obtain a sodium fluoride hydrogen fluoride solution with a mass concentration of 30%, which was stored for later use at 10-15° C. under the protection of nitrogen. The sodium fluoride hydrogen fluoride solution preparation kettle was divided into AB kettles which were used interchangeably.

[0097] (3) The phosphorus pentachloride chlorobenzene solution was continuously input into the microreactor at the speed of 550 g/min via a metering pump, the lithium fluoride hydrogen fluoride solution was continuously input into the microreactor at the speed of 73.94 g/min via the metering pump, the two materials were sufficiently mixed at the inlet of the microreactor and then reacted in the microreactor, the microreactor adopted step temperature control, wherein the maximum temperature in the middle of the microreactor was controlled at 70-75° C., and the temperature of the outlet of the microreactor was controlled at −10 to −5° C., and the materials stayed for about 70 seconds in the microreactor.

[0098] (4) The reaction solution flew out of the microreactor and then entered a continuous gas-liquid separator, wherein the temperature of the gas-liquid separator was controlled at −5 to 0° C., the gas separated from the gas-liquid separator entered the hydrogen chloride treatment system, the liquid separated from the gas-liquid separator entered a collection kettle, wherein the temperature of the collection kettle was controlled at −5 to 5° C. The collection kettle was divided into AB kettles which were used interchangeably.

[0099] (5) After the material in the collection kettle was completely collected, the temperature of the collection kettle was slowly raised to 50-55° C. so that hydrogen fluoride was removed by evaporation, the hydrogen fluoride steam entered a hydrogen fluoride recovery system, dry nitrogen was introduced after hydrogen fluoride was basically removed to purge the materials for 2 hours at 50-55° C., the temperature of the collection kettle was reduced to 25-25° C. after purging was ended, then a sodium hexafluorophosphate wet solid was obtained by centrifugation, and centrifuge mother liquor was used as recovered chlorobenzene to return back to a chlorobenzene groove of a phosphorus pentachloride chlorobenzene solution preparation process.

[0100] (6) The sodium hexafluorophosphate wet solid entered a single-cone spiral belt dryer via a solid material delivery system to be dried at reduced pressure, and then packaged through an automatic passage machine after being qualified via detection.

[0101] The hydrogen chloride treatment system: the hydrogen chloride treatment system consists of a three-stage tandem condenser, a two-stage defluorination packing tower, a three-stage falling film absorber and a two-stage alkali spraying tower. In the three-stage tandem condenser, a −35 to −30° C. frozen liquid was introduced, and hydrogen fluoride entrained in hydrogen chloride was condensed and recovered; in the two-stage defluorination packing tower, a hydrogen fluoride adsorption filler was loaded in the tower to remove a small amount of residual hydrogen fluoride in hydrogen chloride subjected to condensation and defluorination; high-pure hydrogen chloride obtained by defluorination treatment was absorbed with water in the three-stage falling film absorber to obtain a hydrogen chloride solution with a concentration of 35-36%; after being deacidified by secondary alkali spraying, the tail gas met the standard to be discharged.

[0102] The hydrogen fluoride recovery system: a three-stage tandem condenser, a three-stage falling film absorber and a two-stage alkali spraying tower. In the three-stage tandem condenser, a −35 to −30° C. frozen liquid was introduced, most of the hydrogen fluoride was condensed and recovered; residual hydrogen fluoride in the tail gas was absorbed with water in the three-stage falling film absorber to obtain a hydrofluoric acid solution with a concentration of 49±0.2%; after being deacidified by secondary alkali spraying, the tail gas met the standard to be discharged.

[0103] The synthesis of sodium hexafluorophosphate in this example spent 10 hours from starting feeding to stable debugging. Starting from the completion of debugging, timing was started and stable operation was carried out for 300 hours. The results are summarized as follows: a total of 1980 kg of phosphorus pentachloride and 399 kg of sodium fluoride were consumed, resulting in 1589 kg of sodium hexafluorophosphate finished product with a yield of 99.5% and a purity of 99.83%.

Example 3

[0104] Potassium hexafluorophosphate was synthesized by using a microreactor as a continuous reactor, phosphorus pentachloride, potassium chloride and hydrogen fluoride as raw materials and chloroform as an inert organic solvent. By combining with a process flowchart 1, the synthesis process was as follows:

[0105] (1) quantitative chloroform was added into a phosphorus pentachloride chloroform solution preparation kettle, a quantitative phosphorus pentachloride solid was added under the protection of nitrogen, the temperature was raised to 40-45° C. under the condition of stirring, the temperature was reduced to 20-25° C. after the solid was completely dissolved, so as to obtain a phosphorus pentachloride chloroform solution with a mass concentration of 30%, which was stored for later use under the protection of nitrogen. The phosphorus pentachloride chloroform solution preparation kettle was divided into AB kettles which were used interchangeably.

[0106] (2) A quantitative anhydrous hydrogen fluoride liquid was added to a potassium fluoride hydrogen fluoride solution preparation kettle, the temperature was controlled at −15 to −10° C. under the protection of nitrogen, and then a quantitative potassium chloride solid was slowly added in batch and dissolved under the condition of stirring, so as to obtain a potassium fluoride hydrogen fluoride solution with amass concentration of 35%, which was stored for later use at −15 to −10° C. under the protection of nitrogen; the hydrogen chloride gas generated in the preparation process entered a hydrogen chloride treatment system. The potassium fluoride hydrogen fluoride solution preparation kettle was divided into AB kettles which were used interchangeably.

[0107] (3) The phosphorus pentachloride chloroform solution was continuously input into the microreactor at the speed of 450 g/min via a metering pump, the potassium fluoride hydrogen fluoride solution was continuously input into the microreactor at the speed of 107.62 g/min via the metering pump, the two materials were sufficiently mixed at the inlet of the microreactor and then reacted in the microreactor, the microreactor adopted step temperature control, wherein the maximum temperature in the middle of the microreactor was controlled at 40-45° C., and the temperature of the outlet of the microreactor was controlled at −15 to −10° C., and the materials stayed for about 90 seconds in the microreactor.

[0108] (4) The reaction solution flew out of the mciroreactor and then entered a continuous gas-liquid separator, wherein the temperature of the gas-liquid separator was controlled at −10 to −5° C., the gas separated from the gas-liquid separator entered the hydrogen chloride treatment system, the liquid separated from the gas-liquid separator entered a collection kettle, wherein the temperature of the collection kettle was controlled at 0-5° C. The collection kettle was divided into AB kettles which were used interchangeably.

[0109] (5) After the material in the collection kettle was completely collected, the temperature of the collection kettle was slowly raised to 50-55° C. so that hydrogen fluoride was removed by evaporation, the hydrogen fluoride steam entered a hydrogen fluoride recovery system, the temperature of the collection kettle was reduced to 0-5° C. after removal of hydrogen fluoride was ended, the material was subjected to filter press to obtain a potassium hexafluorophosphate wet solid, and mother liquor after filter press was used as recovered chloroform to return back to a chloroform groove of a phosphorus pentachloride chloroform solution preparation process.

[0110] (6) The potassium hexafluorophosphate wet solid entered a single-cone spiral belt dryer via a solid material delivery system to be dried at reduced pressure, and then packaged through an automatic passage machine after being qualified via detection.

[0111] The hydrogen chloride treatment system: the hydrogen chloride treatment system consists of a three-stage tandem condenser, a two-stage defluorination packing tower, a three-stage falling film absorber and a two-stage alkali spraying tower. In the three-stage tandem condenser, a −35 to −30° C. frozen liquid was introduced, and hydrogen fluoride entrained in hydrogen chloride was condensed and recovered; in the two-stage defluorination packing tower, a hydrogen fluoride adsorption filler was loaded in the tower to remove a small amount of residual hydrogen fluoride in hydrogen chloride subjected to condensation and defluorination; high-pure hydrogen chloride obtained by defluorination treatment was absorbed with water in the three-stage falling film absorber to obtain a hydrogen chloride solution with a concentration of 35-36%; after being deacidified by secondary alkali spraying, the tail gas met the standard to be discharged.

[0112] The hydrogen fluoride recovery system: the hydrogen fluoride recovery system consists of a three-stage tandem condenser, a three-stage falling film absorber, and a two-stage alkali spraying tower. In the three-stage tandem condenser, a −35 to −30° C. frozen liquid was introduced, most of the hydrogen fluoride was condensed and recovered; hydrogen fluoride left in the tail gas was absorbed with water in the three-stage falling film absorber to obtain a hydrofluoric acid solution with a concentration of 49±0.2%; after being deacidified by secondary alkali spraying, the tail gas met the standard to be discharged.

[0113] The synthesis of potassium hexafluorophosphate in this example spent 10 hours from starting feeding to stable debugging. Starting from the completion of debugging, timing was started and stable operation was carried out for 300 hours. The results are summarized as follows: a total of 2430 kg of phosphorus pentachloride and 870 kg of potassium chloride were consumed, resulting in 2131 kg of potassium hexafluorophosphate finished product with a yield of 99.2% and a purity of 99.88%.

Example 4

[0114] Sodium hexafluorophosphate was synthesized by using a microreactor as a continuous reactor, phosphorus pentachloride, sodium chloride and hydrogen fluoride as raw materials and toluene as an inert organic solvent. By combining with a process flowchart 1, the synthesis process was as follows:

[0115] (1) quantitative m-dichlorobenzene was added into a phosphorus pentachloride m-dichlorobenzene solution preparation kettle, a quantitative phosphorus pentachloride solid was added under the protection of nitrogen, the temperature was raised to 70-75° C. under the condition of stirring, the temperature was reduced to 25-30° C. after the solid was completely dissolved, so as to obtain a phosphorus pentachloride m-dichlorobenzene solution with a mass concentration of 30%, which was stored for later use under the protection of nitrogen. The phosphorus pentachloride m-dichlorobenzene solution preparation kettle was divided into AB kettles which were used interchangeably.

[0116] (2) A quantitative anhydrous hydrogen fluoride liquid was added to a sodium fluoride hydrogen fluoride solution preparation kettle, the temperature was controlled at 0-5° C. under the protection of nitrogen, and then a quantitative sodium chloride solid was slowly added in batch and dissolved under the condition of stirring, so as to obtain a sodium fluoride hydrogen fluoride solution with a mass concentration of 25%, which was stored for later use at 0 to 5° C. under the protection of nitrogen; the hydrogen chloride gas generated in the preparation process entered a hydrogen chloride treatment system. The sodium fluoride hydrogen fluoride solution preparation kettle was divided into AB kettles which were used interchangeably.

[0117] (3) The phosphorus pentachloride m-dichlorobenzene solution was continuously input into the microreactor at the speed of 450 g/min via a metering pump, the sodium fluoride hydrogen fluoride solution was continuously input into the microreactor at the speed of 108.89 g/min via the metering pump, the two materials were sufficiently mixed at the inlet of the microreactor and then reacted in the microreactor, and the microreactor adopted step temperature control, wherein the maximum temperature in the middle of the microreactor was controlled at 30-35° C., and the temperature of the outlet of the microreactor was controlled at −5 to 0° C., and the materials stayed for about 90 seconds in the microreactor.

[0118] (4) The reaction solution flew out of the mciroreactor and then entered a continuous gas-liquid separator, wherein the temperature of the gas-liquid separator was controlled at −5 to 0° C., the gas separated from the gas-liquid separator entered the hydrogen chloride treatment system, and the liquid separated from the gas-liquid separator entered a collection kettle, wherein the temperature of the collection kettle was controlled at −5 to 0° C. The collection kettle was divided into AB kettles which were used interchangeably.

[0119] (5) After the material in the collection kettle was completely collected, the temperature of the collection kettle was slowly raised to 60-65° C., hydrogen fluoride was removed by evaporation, the hydrogen fluoride steam entered a hydrogen fluoride recovery system, dry nitrogen was introduced after most of the hydrogen fluoride was removed to purge the materials for 2 hours at 60-65° C., the temperature of the collection kettle was reduced to 15-20° C. after purging was ended, then a sodium hexafluorophosphate wet solid was obtained by centrifugation, and centrifuge mother liquor was used as recovered m-dichlorobenzene to return back to an m-dichlorobenzene groove of a phosphorus pentachloride m-dichlorobenzene solution preparation process.

[0120] (6) The sodium hexafluorophosphate wet solid entered a single-cone spiral belt dryer via a solid material delivery system to be dried at reduced pressure, and then packaged through an automatic passage machine after being qualified via detection.

[0121] The hydrogen chloride treatment system: the hydrogen chloride treatment system consists of a three-stage tandem condenser, a two-stage defluorination packing tower, a three-stage falling film absorber and a two-stage alkali spraying tower. In the three-stage tandem condenser, a −35 to −30° C. frozen liquid was introduced, and hydrogen fluoride entrained in hydrogen chloride was condensed and recovered; in the two-stage defluorination packing tower, a hydrogen fluoride adsorption filler was loaded in the tower to remove a small amount of residual hydrogen fluoride in hydrogen chloride subjected to condensation and defluorination; high-pure hydrogen chloride obtained by defluorination treatment was absorbed with water in the three-stage falling film absorber to obtain a hydrogen chloride solution with a concentration of 35-36%; after being deacidified by secondary alkali spraying, the tail gas met the standard to be discharged.

[0122] The hydrogen fluoride recovery system: the hydrogen fluoride recovery system consists of a three-stage tandem condenser, a three-stage falling film absorber, and a two-stage alkali spraying tower. In the three-stage tandem condenser, a −35 to −30° C. frozen liquid was introduced, most of the hydrogen fluoride was condensed and recovered; hydrogen fluoride left in the tail gas was absorbed with water in the three-stage falling film absorber to obtain a hydrofluoric acid solution with a concentration of 49±0.2%; after being deacidified by secondary alkali spraying, the tail gas met the standard to be discharged.

[0123] The synthesis of sodium hexafluorophosphate in this example spent 10 hours from starting feeding to stable debugging. Starting from the completion of debugging, timing was started and stable operation was carried out for 300 hours. The results are summarized as follows: a total of 2430 kg of phosphorus pentachloride and 682 kg of sodium chloride were consumed, resulting in 1942 kg of lithium hexafluorophosphate finished product with a yield of 99.1% and a purity of 99.90%.

Example 5

[0124] Lithium hexafluorophosphate was synthesized by using a microreactor as a continuous reactor, phosphorus pentachloride, lithium fluoride and hydrogen fluoride as raw materials and toluene as an inert organic solvent. By combining with a process flowchart 1, the synthesis process was as follows:

[0125] (1) quantitative dichloroethane was added into a phosphorus pentachloride dichloroethane solution preparation kettle, a quantitative phosphorus pentachloride solid was added under the protection of nitrogen, the temperature was raised to 60-65° C. under the condition of stirring, the temperature was reduced to 20-25° C. after the solid was completely dissolved, so as to obtain a phosphorus pentachloride dichloroethane solution with a mass concentration of 25%, which was stored for later use under the protection of nitrogen. The phosphorus pentachloride dichloroethane solution preparation kettle was divided into AB kettles which were used interchangeably.

[0126] (2) A quantitative anhydrous hydrogen fluoride liquid was added to a lithium fluoride hydrogen fluoride solution preparation kettle, the temperature was controlled at 5-10° C. under the protection of nitrogen, and then a quantitative lithium fluoride solid was slowly added in batch and dissolved under the condition of stirring, so as to obtain a lithium fluoride hydrogen fluoride solution with a mass concentration of 25%, which was stored for later use at 5-10° C. under the protection of nitrogen. The lithium fluoride hydrogen fluoride solution preparation kettle was divided into AB kettles which were used interchangeably.

[0127] (3) The phosphorus pentachloride dichloroethane solution was continuously input into the microreactor at the speed of 500 g/min via a metering pump, the lithium fluoride hydrogen fluoride solution was continuously input into the microreactor at the speed of 62.28 g/min via the metering pump, the two materials were sufficiently mixed at the inlet of the microreactor and then reacted in the microreactor, the microreactor adopted step temperature control, wherein the maximum temperature in the middle of the microreactor was controlled at 50-55° C., and the temperature of the outlet of the microreactor was controlled at 0-5° C., and the materials stayed for about 80 seconds in the microreactor.

[0128] (4) The reaction solution flew out of the mciroreactor and then entered a continuous gas-liquid separator, wherein the temperature of the gas-liquid separator was controlled at −20 to −15° C., the gas separated from the gas-liquid separator entered the hydrogen chloride treatment system, the liquid separated from the gas-liquid separator entered a collection kettle, wherein the temperature of the collection kettle was controlled at −5 to 5° C. The collection kettle was divided into AB kettles which were used interchangeably.

[0129] (5) After the material in the collection kettle was completely collected, the temperature of the collection kettle was slowly raised to 60-65° C., hydrogen fluoride was removed by evaporation, the hydrogen fluoride steam entered a hydrogen fluoride recovery system, after removal of the hydrogen fluoride was ended, the temperature of the collection kettle was reduced to 10-15° C., then a lithium hexafluorophosphate wet solid was obtained by centrifugation, and centrifuge mother liquor was used as recovered dichloroethane to return back to a dichloroethane groove of a phosphorus pentachloride dichloroethane solution preparation process.

[0130] (6) The lithium hexafluorophosphate wet solid entered a single-cone spiral belt dryer via a solid material delivery system to be dried at reduced pressure, and then packaged through an automatic passage machine after being qualified via detection.

[0131] The hydrogen chloride treatment system: the hydrogen chloride treatment system consists of a three-stage tandem condenser, a two-stage defluorination packing tower, a three-stage falling film absorber and a two-stage alkali spraying tower. In the three-stage tandem condenser, a −35 to −30° C. frozen liquid was introduced, and hydrogen fluoride entrained in hydrogen chloride was condensed and recovered; in the two-stage defluorination packing tower, a hydrogen fluoride adsorption filler was loaded in the tower to remove a small amount of residual hydrogen fluoride in hydrogen chloride subjected to condensation and defluorination; high-pure hydrogen chloride obtained by defluorination treatment was absorbed with water in the three-stage falling film absorber to obtain a hydrogen chloride solution with a concentration of 35-36%; after being deacidified by secondary alkali spraying, the tail gas met the standard to be discharged.

[0132] The hydrogen fluoride recovery system: the hydrogen fluoride recovery system consists of a three-stage tandem condenser, a three-stage falling film absorber, and a two-stage alkali spraying tower. In the three-stage tandem condenser, a −35 to −30° C. frozen liquid was introduced, most of the hydrogen fluoride was condensed and recovered; hydrogen fluoride left in the tail gas was absorbed with water in the three-stage falling film absorber to obtain a hydrofluoric acid solution with a concentration of 49±0.2%; after being deacidified by secondary alkali spraying, the tail gas met the standard to be discharged.

[0133] The synthesis of lithium hexafluorophosphate in this example spent 10 hours from starting feeding to stable debugging. Starting from the completion of debugging, timing was started and stable operation was carried out for 300 hours. The results are summarized as follows: a total of 2250 kg of phosphorus pentachloride and 280 kg of lithium fluoride were consumed, resulting in 1631 kg of lithium hexafluorophosphate finished product with a yield of 99.4% and a purity of 99.86%.

Example 6

[0134] Potassium hexafluorophosphate was synthesized by using a microreactor as a continuous reactor, phosphorus pentachloride, potassium bromide and hydrogen fluoride as raw materials and methylcyclohexane as an inert organic solvent. By combining with a process flowchart 1, the synthesis process was as follows:

[0135] (1) quantitative methylcyclohexane was added into a phosphorus pentachloride methylcyclohexane solution preparation kettle, a quantitative phosphorus pentachloride solid was added under the protection of nitrogen, the temperature was raised to 30-35° C. under the condition of stirring, a phosphorus pentachloride methylcyclohexane solution with a mass concentration of 15% was obtained after the solid was completely dissolved, which was stored for later use under the protection of nitrogen. The phosphorus pentachloride methylcyclohexane solution preparation kettle was divided into AB kettles which were used interchangeably.

[0136] (2) A quantitative anhydrous hydrogen fluoride liquid was added to a potassium fluoride hydrogen fluoride solution preparation kettle, the temperature was controlled at −5 to 0° C. under the protection of nitrogen, and then a quantitative potassium bromide solid was slowly added in batch and dissolved under the condition of stirring, so as to obtain a potassium fluoride hydrogen fluoride solution with amass concentration of 40%, which was stored for later use at −5 to 0° C. under the protection of nitrogen; the hydrogen bromide gas generated in the preparation process entered a hydrogen bromide treatment system. The potassium fluoride hydrogen fluoride solution preparation kettle was divided into AB kettles which were used interchangeably.

[0137] (3) The phosphorus pentachloride methylcyclohexane solution was continuously input into the microreactor at the speed of 600 g/min via a metering pump, the potassium fluoride hydrogen fluoride solution was continuously input into the microreactor at the speed of 30.37 g/min via the metering pump, the two materials were sufficiently mixed at the inlet of the microreactor and then reacted in the microreactor, and the microreactor adopted step temperature control, wherein the maximum temperature in the middle of the microreactor was controlled at 80-85° C., and the temperature of the outlet of the microreactor was controlled at −10 to −5° C., and the materials stayed for about 60 seconds in the microreactor.

[0138] (4) The reaction solution flew out of the mciroreactor and then entered a continuous gas-liquid separator, wherein the temperature of the gas-liquid separator was controlled at −10 to −5° C., the gas separated from the gas-liquid separator entered the hydrogen bromide treatment system, and the liquid separated from the gas-liquid separator entered a collection kettle, wherein the temperature of the collection kettle was controlled at −5 to 5° C. The collection kettle was divided into AB kettles which were used interchangeably.

[0139] (5) After the material in the collection kettle was completely collected, the temperature of the collection kettle was slowly raised to 70-75° C., hydrogen fluoride was removed by evaporation, the hydrogen fluoride steam entered a hydrogen fluoride recovery system, the temperature of the collection kettle was reduced to 20-25° C. after removal of hydrogen fluoride was ended, then a potassium hexafluorophosphate wet solid was obtained by filter pressing, and mother liquor obtained after filter pressing was used as recovered methylcyclohexane to return back to a methylcyclohexane groove of a phosphorus pentachloride methylcyclohexane solution preparation process.

[0140] (6) The potassium hexafluorophosphate wet solid entered a single-cone spiral belt dryer via a solid material delivery system to be dried at reduced pressure, and then packaged through an automatic passage machine after being qualified via detection.

[0141] The hydrogen bromide treatment system: the hydrogen bromide treatment system consists of a three-stage tandem condenser, a two-stage defluorination packing tower, a three-stage falling film absorber and a two-stage alkali spraying tower. In the three-stage tandem condenser, a −35 to −30° C. frozen liquid was introduced, and hydrogen fluoride entrained in hydrogen bromide was condensed and recovered; in the two-stage defluorination packing tower, a hydrogen fluoride adsorption filler was loaded in the tower to remove a small amount of residual hydrogen fluoride in hydrogen bromide after condensation and defluorination; high-pure hydrogen bromide obtained by defluorination treatment was absorbed with water in the three-stage falling film absorber to obtain a hydrogen bromide solution with a concentration of 46-48%; after being deacidified by secondary alkali spraying, the tail gas met the standard to be discharged.

[0142] The hydrogen fluoride recovery system: the hydrogen fluoride recovery system consists of a three-stage tandem condenser, a three-stage falling film absorber, and a two-stage alkali spraying tower. In the three-stage tandem condenser, a −35 to −30° C. frozen liquid was introduced, most of the hydrogen fluoride was condensed and recovered; hydrogen fluoride left in the tail gas was absorbed with water in the three-stage falling film absorber to obtain a hydrofluoric acid solution with a concentration of 49±0.2%; after being deacidified by secondary alkali spraying, the tail gas met the standard to be discharged.

[0143] The synthesis of potassium hexafluorophosphate in this example spent 10 hours from starting feeding to stable debugging. Starting from the completion of debugging, timing was started and stable operation was carried out for 300 hours. The results are summarized as follows: a total of 1620 kg of phosphorus pentachloride and 448 kg of potassium bromide were consumed, resulting in 688 kg of potassium hexafluorophosphate finished product with a yield of 99.3% and a purity of 99.84%.