Method and device for rectifying trifluoromethanesulfonyl fluoride

Abstract

The invention provides a method for rectifying trifluoromethanesulfonyl fluoride, which can be used for effectively purifying trifluoromethanesulfonyl fluoride feed gas containing impurity gases such as HF, CO2, SO2 and the like, and comprises the following steps of: obtaining an azeotrope of trifluoromethanesulfonyl fluoride and HF by using a conventional rectifying process, condensing the azeotrope, settling, splitting phases, and rectifying and purifying again, thereby obtaining the trifluoromethanesulfonyl fluoride. The problem that trifluoromethanesulfonyl fluoride and HF cannot be thoroughly separated through azeotropic distillation is solved. The invention also provides a rectification device of the trifluoromethanesulfonyl fluoride, the rectification device comprises a collecting tower, a light component removal tower, a heavy component removal tower, a settling separation tank and a finished product rectification tower which are connected in sequence, continuous rectification preparation of the high-purity trifluoromethanesulfonyl fluoride is realized, and the purity of the high-purity trifluoromethanesulfonyl fluoride is not less than 99.5%.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical preparation, and in particular relates to a distillation method and device for trifluoromethanesulfonyl fluoride. Background Art

[0002] Trifluoromethanesulfonyl fluoride is an important and indispensable intermediate product in the preparation of trifluoromethanesulfonic acid and bis(trifluoromethanesulfonyl)imide series products. As the strongest organic acid, trifluoromethanesulfonic acid has a wide range of applications, including the preparation of various trifluoromethanesulfonates, silicone greases, trifluoromethanesulfonic anhydride and other products. The bis(trifluoromethanesulfonyl)imide series is mainly used in the preparation of salts such as lithium bis(trifluoromethanesulfonyl)imide and sodium bis(trifluoromethanesulfonyl)imide, which are mostly used in lithium batteries, energy storage batteries and other fields. The purification process of a purification method of trifluoromethanesulfonyl fluoride in Chinese patent CN104387300A has problems such as HF azeotropy, and the purity is low, which affects the yield of the subsequent product preparation process.

[0003] The purification method of hydrogen fluoride in a trifluoromethanesulfonyl fluoride of Chinese patent CN114470866A also mentions that crude trifluoromethanesulfonyl fluoride liquid usually contains hydrogen fluoride impurities, and trifluoromethanesulfonyl fluoride and hydrogen fluoride can form azeotropes, and hydrogen fluoride cannot be removed cleanly by traditional distillation methods.Again, because the content of hydrogen fluoride contained in crude trifluoromethanesulfonyl fluoride liquid is higher, directly using adsorbent to adsorb hydrogen fluoride will cause the collapse of adsorbent.Therefore, it is particularly important to develop a purification method of hydrogen fluoride in a trifluoromethanesulfonyl fluoride.This method utilizes the effect between hydrogen fluoride and extraction agent, thereby changes the relative volatility between hydrogen fluoride and trifluoromethanesulfonyl fluoride, can remove most of hydrogen fluoride, is convenient to the carrying out of subsequent distillation process, and the cost of adding extraction agent is higher. Summary of the invention

[0004] The present invention also provides a trifluoromethanesulfonyl fluoride distillation method and device, which realize the continuous distillation preparation of high-purity trifluoromethanesulfonyl fluoride with a purity of not less than 99.5%.

[0005] The technical solution adopted by the present invention is:

[0006] A trifluoromethanesulfonyl fluoride distillation method comprises the following steps: crude trifluoromethanesulfonyl fluoride gas is passed into a collection tower for cooling and collection, the collection tower is cooled by liquid nitrogen, the obtained condensate is transported to a light removal tower by a delivery pump, the light impurities (CO2 and SO2) are discharged from the top of the tower after distillation in the light removal tower, the tower bottom liquid enters a de-weighting tower for distillation; the heavy impurities (HF) at the bottom of the de-weighting tower are recovered, and the output product at the top of the de-weighting tower enters a sedimentation separation tank for sedimentation separation; the lower layer liquid of the sedimentation separation tank is transferred to a finished product distillation tower for distillation, and the upper layer liquid of the sedimentation separation tank is transferred back to the de-weighting tower for distillation again; the liquid discharged from the top of the finished product distillation tower is returned to the sedimentation separation tank, and the finished product trifluoromethanesulfonyl fluoride is produced from the bottom of the tower by the bottom liquid of the finished product distillation tower. The purity of the trifluoromethanesulfonyl fluoride produced is not less than 99.5%.

[0007] Preferably, the cooling and collecting pressure is 0-0.010 MPa, and the temperature is controlled at -55--105°C; the operating pressure of the light-removing tower is 0.310-0.330 MPa, the exhaust temperature at the top of the tower is controlled at -8--15°C, and the bottom temperature is 11-21°C; the operating pressure of the heavy-removing tower is 0.190-0.210 MPa, the top temperature is 3-5°C, and the bottom temperature is 26-34°C.

[0008] Preferably, two sedimentation separation tanks are provided, which are used alternately in sedimentation and discharging states. In the sedimentation state, the temperature in the sedimentation separation tank is controlled to -20 to -30°C, which can ensure that trifluoromethanesulfonyl fluoride and HF are settled and layered in the liquid phase; in the discharging state, the jacket refrigerant can be closed, and the pressure in the sedimentation separation tank can be increased to 0.250 to 0.300 MPa to feed the finished product distillation tower. The sedimentation separation tank is 2 cubic meters in size, and the ratio of height to diameter is 2 to 3, which is convenient for sedimentation separation.

[0009] Preferably, the operating pressure of the finished product distillation tower is 0.190-0.210 MPa, the tower top temperature is 5-7°C, and the tower bottom temperature is 5-7°C.

[0010] Preferably, the light impurities include CO2 and SO2; and the heavy impurities include HF.

[0011] A special distillation device for trifluoromethanesulfonyl fluoride comprises a collecting tower, a light removal tower, a heavy removal tower, a sedimentation separation tank and a finished product distillation tower which are connected in sequence.

[0012] Preferably, the collecting tower is provided with a collecting tower crude product feed inlet, a collecting tower liquid return inlet, a tower bottom liquefied material storage area, a collecting tower bottom discharge port and a collecting tower top venting port, and a collecting tower top is provided with a condenser to condense the crude product gas using liquid nitrogen;

[0013] The lightness removal tower is provided with a tower body feed port, a tower bottom discharge port and a tower top exhaust port;

[0014] The deweighting tower is provided with a deweighting tower body feed inlet, a deweighting tower body return inlet, a deweighting tower top discharge inlet and a deweighting tower bottom discharge inlet;

[0015] The sedimentation separation tank is provided with a feed inlet at the top of the sedimentation separation tank and a discharge outlet at the bottom of the sedimentation separation tank;

[0016] The finished product distillation tower is provided with a finished product distillation tower body feed inlet, a finished product distillation tower top discharge outlet, and a finished product distillation tower bottom discharge outlet;

[0017] The bottom discharge port of the collecting tower is connected to the feed port of the light removal tower body, the bottom discharge port of the light removal tower is connected to the feed port of the heavy removal tower body, the return port of the heavy removal tower body is connected to the bottom discharge port of the sedimentation separation tank, the top discharge port of the heavy removal tower is connected to the feed port of the top of the sedimentation separation tank, the bottom discharge port of the sedimentation separation tank is connected to the feed port of the finished distillation tower body, and the top discharge port of the finished distillation tower is connected to the feed port of the top of the sedimentation separation tank.

[0018] When the above device is in operation, the raw material gas is fed from the crude product feed port of the collecting tower, liquefied by the tower top condenser and stored in the liquefied material storage area at the bottom of the tower, and the liquid in the collecting tower is transported to the feed port of the light removal tower body and the liquid return port of the collecting tower by a low-temperature delivery pump; the liquefied raw material is preliminarily distilled in the light removal tower, and the light impurities are discharged from the top of the light removal tower to the tail gas treatment device for treatment, and the liquid qualified for light removal enters the heavy removal tower from the bottom discharge port of the light removal tower for distillation, and the HF heavy impurities are discharged from the bottom of the heavy removal tower. The crude trifluoromethanesulfonyl fluoride product is produced at the top of the heavy removal tower and enters the sedimentation separation tank from the feed port at the top of the sedimentation separation tank. The bottom discharge port of the sedimentation separation tank is respectively connected with the feed port of the finished product distillation tower body and the return port of the de-weighting tower body. The finished product-rich phase at the bottom of the sedimentation separation tank is separated to the finished product distillation tower, and the remaining HF-rich phase is separated and returned to the de-weighting tower. The liquid collected from the top discharge port of the finished product distillation tower is returned to the sedimentation separation tank for sedimentation separation. More than 99.5% of the trifluoromethanesulfonyl fluoride product is collected from the bottom discharge port of the finished product distillation tower.

[0019] Preferably, the light removal tower, heavy removal tower and finished product distillation tower are all provided with a condensing heat exchanger at the top of the tower, and a reboiler is provided at the bottom of the tower. The top condenser uses a refrigerant to cool and condense, and the bottom reboiler uses hot water to heat and reboil.

[0020] Preferably, a delivery pump is provided between the collecting tower and the light-removing tower, one end of the delivery pump is connected to the discharge port at the bottom of the collecting tower, and the other end is respectively connected to the liquid return port of the collecting tower and the feed port of the tower body of the light-removing tower; the liquid level of the collecting tower is interlocked with the delivery pump for control, and when the liquid level is higher than the set value, the liquefied crude product is delivered to the feed port of the tower body of the light-removing tower; when the liquid level is lower than the set value, the liquefied crude product is returned to the liquid return port of the collecting tower and enters the collection tower circulation.

[0021] Preferably, the light-removal tower, heavy-removal tower and finished product distillation tower are all packed towers.

[0022] The beneficial effects of the present invention are:

[0023] The process route of the invention is relatively simple, the process reliability is high, the continuous operability is strong, and the trifluoromethanesulfonyl fluoride product with a purity of more than 99.5% can be prepared. The high-purity product can effectively improve the yield of subsequent preparation of trifluoromethanesulfonic acid and bis(trifluoromethanesulfonyl)imide series products. The invention is simple to operate, can be continuously produced, improves product quality, and reduces product cost.

[0024] The trifluoromethanesulfonyl fluoride raw material gas of the present invention contains trifluoromethanesulfonyl fluoride and impurity gases such as HF, CO2, SO2, etc. The present invention uses a conventional distillation method to remove CO2, SO2 and part of HF, and then condenses and collects the azeotropic mixture of HF and trifluoromethanesulfonyl fluoride, and then allows the mixture to settle and separate phases, and then distills again, thereby effectively solving the problem that trifluoromethanesulfonyl fluoride and HF cannot be separated in the distillation separation. The distillation preparation method of trifluoromethanesulfonyl fluoride of the present invention effectively solves the problem that the trifluoromethanesulfonyl fluoride product and HF are azeotropic, and can produce high-purity trifluoromethanesulfonyl fluoride, which can effectively improve the quality and cost of subsequent products. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the structure of the trifluoromethanesulfonyl fluoride distillation device of the present invention.

[0026] In the attached drawings, 1-collecting tower, 2-light-removing tower, 3-heavy-removing tower, 4-sedimentation separation tank, 5-finished product distillation, and 6-transporting pump.

[0027] Figure 2 This is the nuclear magnetic resonance fluorine spectrum detection diagram of trifluoromethanesulfonyl fluoride, the finished product of Example 1. DETAILED DESCRIPTION

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the embodiments will be briefly introduced below. Obviously, the following description only describes some embodiments of the present invention. For ordinary technicians in this field, other embodiments can be obtained without creative work.

[0029] Device Embodiment

[0030] like Figure 1 As shown, a special distillation device for trifluoromethanesulfonyl fluoride comprises a collecting tower 1, a delivery pump 6, a light removal tower 2, a heavy removal tower 3, a sedimentation separation tank 4 (the size of the sedimentation separation tank is 2 cubic meters, and the ratio of height to diameter is 3) and a finished product distillation tower 5 which are connected in sequence; the light removal tower 2, the heavy removal tower 3 and the finished product distillation tower 5 are all packed towers, and a condensing heat exchanger is arranged at the top of the tower, and a reboiler is arranged at the bottom of the tower, the top condenser uses a refrigerant to cool and condense, and the bottom reboiler uses hot water to heat and reboil.

[0031] The collecting tower 1 is provided with a collecting tower crude product feed inlet, a collecting tower liquid return inlet, a tower bottom liquefied material storage area, a collecting tower bottom discharge port and a collecting tower top venting port. A condenser is provided on the collecting tower top to condense the crude product gas using liquid nitrogen; the de-lightening tower 2 is provided with a de-lightening tower body feed inlet, a de-lightening tower bottom discharge port and a de-lightening tower top exhaust port; a delivery pump 6 (CAM2 / 3 low-temperature shielded pump) is provided between the collecting tower 1 and the de-lightening tower 2, one end of the delivery pump 6 is connected to the collecting tower bottom discharge port, and the other end is respectively connected to the collecting tower liquid return port and the de-lightening tower body feed inlet; the collecting tower liquid level is interlocked with the delivery pump 6, and when the liquid level is higher than the set value, the liquefied crude product is delivered to the de-lightening tower body feed inlet; when the liquid level is lower than the set value, the liquefied crude product is returned to the collecting tower liquid return port and enters the collecting tower circulation. The bottom discharge port of the light removal tower is connected to the feed port of the heavy removal tower body. The heavy removal tower 3 is provided with a feed port of the heavy removal tower body, a return port of the heavy removal tower body, a top discharge port of the heavy removal tower and a bottom discharge port of the heavy removal tower; the sedimentation separation tank 4 is provided with a feed port at the top of the sedimentation separation tank and a bottom discharge port of the sedimentation separation tank; the return port of the heavy removal tower body is connected to the bottom discharge port of the sedimentation separation tank, and the top discharge port of the heavy removal tower is connected to the top feed port of the sedimentation separation tank; the finished product distillation tower 5 is provided with a feed port of the finished product distillation tower body, a top discharge port of the finished product distillation tower and a bottom discharge port of the finished product distillation tower; the bottom discharge port of the sedimentation separation tank is connected to the feed port of the finished product distillation tower body, and the top discharge port of the finished product distillation tower is connected to the feed port of the top of the sedimentation separation tank.

[0032] When the above device is in operation, the raw material gas is fed from the crude product feed port of the collecting tower, liquefied by the top condenser and stored in the liquefied material storage area at the bottom of the tower, and the liquid of the collecting tower 1 is transported to the feed port of the light removal tower body and the liquid return port of the collecting tower by a low-temperature delivery pump; the liquefied raw material is preliminarily distilled in the light removal tower 2, and the light impurities are discharged from the top of the light removal tower 2 to the tail gas treatment device for treatment, and the liquid qualified for light removal enters the heavy removal tower 3 from the bottom discharge port of the light removal tower for distillation, and the HF heavy impurities are discharged from the top of the heavy removal tower 3. The crude trifluoromethanesulfonyl fluoride product is produced at the top of the heavy removal tower 3 and enters the sedimentation separation tank 4 from the feed port at the top of the sedimentation separation tank. The bottom discharge port of the sedimentation separation tank is connected to the feed port of the finished product distillation tower body and the return port of the de-weighting tower body respectively. The product-rich phase at the bottom of the sedimentation separation tank 4 is separated to the finished product distillation tower 5, and the remaining HF-rich phase is separated and returned to the de-weighting tower 3. The liquid collected from the top discharge port of the finished product distillation tower is returned to the sedimentation separation tank 4 for sedimentation separation. More than 99.5% of the trifluoromethanesulfonyl fluoride product is collected from the bottom discharge port of the finished product distillation tower.

[0033] Method Embodiment

[0034] Example 1

[0035] like Figure 1As shown, a method for preparing trifluoromethanesulfonyl fluoride by distillation, using a trifluoromethanesulfonyl fluoride distillation device in the device embodiment, the volume fractions of the components of the crude trifluoromethanesulfonyl fluoride gas are 40% trifluoromethanesulfonyl fluoride, 45% HF, 7% CO2, 5% SO2, and 3% others; the crude gas is fed into a collecting tower 1 through a crude product feed port of the collecting tower for condensation and collection, and the tail gas is discharged at the vent port at the top of the collecting tower, the tail gas discharge temperature is controlled to -55°C, and the pressure of the collecting tower is controlled to 0.01MPa;

[0036] The condensate is pumped into the feed port of the de-lightness tower through a low-temperature shielded pump and enters the de-lightness tower 2. The operating pressure of the de-lightness tower 2 is 0.320MPa. The exhaust is discharged from the exhaust port at the top of the de-lightness tower. The exhaust temperature is controlled at -11°C and the tower kettle temperature is 21°C.

[0037] The condensate enters the de-weighting tower 3 from the bottom outlet of the de-weighting tower through the feed port of the de-weighting tower body. The operating pressure of the de-weighting tower 3 is 0.200MPa, the top temperature is 3°C, and the heavy discharge temperature of the bottom is 34°C.

[0038] The gas from the top of the de-weighting tower 3 enters the settling separation tank 4 from the discharge port at the top of the de-weighting tower through the feed port at the top of the settling separation tank. There are two settling separation tanks 4, which are used alternately in the discharge and settling states. The pressure in the discharge state is controlled at 0.300 MPa. The temperature in the settling separation tank 4 is controlled at -20°C.

[0039] The operating pressure of the finished product distillation tower 5 is 0.210MPa, the bottom product collection temperature is 6.7°C, the tower top collection temperature is 6.2°C, the bottom trifluoromethanesulfonyl fluoride finished product index is 99.80%, the continuous operation product yield of the device is 98.9%, and the product composition is shown in Table 1 and Figure 1 .

[0040] Table 1 Detection index of finished product distillation bis(trifluoromethanesulfonyl fluoride)

[0041] Serial number name index 1 Trifluoromethanesulfonyl fluoride 99.80％ 2 HF 0.2％ 3 <![CDATA[CO2]]> Not detected 4 <![CDATA[SO2]]> Not detected

[0042] Example 2

[0043] like Figure 1 As shown, a method for preparing trifluoromethanesulfonyl fluoride by distillation, using a trifluoromethanesulfonyl fluoride distillation device in the device embodiment, the volume fractions of the components of the crude trifluoromethanesulfonyl fluoride gas are 50% trifluoromethanesulfonyl fluoride, 35% HF, 6% CO2, 6% SO2, and 3% others; the crude gas is fed into a collecting tower 1 through a crude product feed port of the collecting tower for condensation and collection, and the tail gas is discharged at a vent port at the top of the collecting tower, the tail gas discharge temperature is controlled to -85°C, and the pressure of the collecting tower 1 is controlled to 0.001MPa;

[0044] The condensate is pumped into the feed port of the de-lightness tower through a low-temperature shielded pump and enters the de-lightness tower 2. The operating pressure of the de-lightness tower 2 is 0.310MPa. The exhaust is discharged from the exhaust port at the top of the de-lightness tower. The exhaust temperature is controlled at -8°C and the tower kettle temperature is 11°C.

[0045] The condensate enters the de-weighting tower 3 from the bottom discharge port of the de-weighting tower through the feed port of the de-weighting tower body. The operating pressure of the de-weighting tower 3 is 0.210MPa, the tower top temperature is 5°C, and the tower bottom discharge temperature is 31°C.

[0046] The gas from the top of the de-weighting tower 3 enters the settling separation tank 4 from the discharge port at the top of the de-weighting tower through the feed port at the top of the settling separation tank. There are two settling separation tanks 4, which are used alternately in the discharge and settling states. The pressure in the discharge state is controlled at 0.285MPa. The temperature in the settling separation tank 4 is controlled at -30°C.

[0047] The operating pressure of the finished product distillation tower 5 is 0.200 MPa, the bottom product collection temperature is 6.2°C, the top collection temperature is 6.0°C, the bottom trifluoromethanesulfonyl fluoride finished product index is 99.83%, the continuous operation product yield of the device is 98.8%, and the product composition is shown in Table 2.

[0048] Table 2 Detection index of finished product distillation bis(trifluoromethanesulfonyl fluoride)

[0049] Serial number name index 1 Trifluoromethanesulfonyl fluoride 99.83％ 2 HF 0.17％ 3 <![CDATA[CO2]]> Not detected 4 <![CDATA[SO2]]> Not detected

[0050] Example 3

[0051] like Figure 1 As shown, a method for preparing trifluoromethanesulfonyl fluoride by distillation, using a trifluoromethanesulfonyl fluoride distillation device in the device embodiment, the volume fractions of the components of the crude trifluoromethanesulfonyl fluoride gas are 55% trifluoromethanesulfonyl fluoride, 30% HF, 6% CO2, 6% SO2, and 3% others; the crude gas is fed into a collecting tower 1 through a crude product feed port of the collecting tower for condensation and collection, and the tail gas is discharged at a vent port at the top of the collecting tower, the tail gas discharge temperature is controlled to -105°C, and the pressure of the collecting tower 1 is controlled to 0.001MPa;

[0052] The condensate is pumped into the feed port of the de-lightness tower through a low-temperature shielded pump and enters the de-lightness tower 2. The operating pressure of the de-lightness tower 2 is 0.330MPa. The exhaust is discharged from the exhaust port at the top of the de-lightness tower. The exhaust temperature is controlled at -15°C and the tower kettle temperature is 18°C.

[0053] The condensate enters the de-weighting tower 3 from the bottom discharge port of the de-weighting tower through the feed port of the de-weighting tower body. The operating pressure of the de-weighting tower 3 is 0.190MPa, the tower top temperature is 4.5℃, and the tower bottom discharge temperature is 26℃.

[0054] The gas from the top of the de-weighting tower enters the settling separation tank 4 from the discharge port at the top of the de-weighting tower through the feed port at the top of the settling separation tank. There are two settling separation tanks 4, which are used alternately in the discharge and settling states. The pressure in the discharge state is controlled at 0.250 MPa. The temperature in the settling separation tank 4 is controlled at -25°C.

[0055] The operating pressure of the finished product distillation tower 5 is 0.190 MPa, the bottom product collection temperature is 5.2°C, the top collection temperature is 5°C, the bottom trifluoromethanesulfonyl fluoride finished product index is 99.85%, the continuous operation product yield of the device is 98.9%, and the product composition is shown in Table 3.

[0056] Table 3 Detection index of finished product distillation bis(trifluoromethanesulfonyl fluoride)

[0057] Serial number name index 1 Trifluoromethanesulfonyl fluoride 99.85％ 2 HF 0.15％ 3 <![CDATA[CO2]]> Not detected 4 <![CDATA[SO2]]> Not detected

[0058] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A rectification method for trifluoromethanesulfonyl fluoride, characterized in that: The following steps are involved: The crude trifluoromethanesulfonyl fluoride gas is cooled and collected, and the obtained condensate is transported to a light-removal tower. After distillation in the light-removal tower, the light impurities are discharged from the top of the tower, and the bottom liquid enters a heavy-removal tower for distillation; the heavy impurities at the bottom of the heavy-removal tower are recovered, and the output product at the top of the heavy-removal tower enters a sedimentation separation tank for sedimentation separation; the lower layer of the liquid in the sedimentation separation tank is transferred to a finished product distillation tower for distillation, and the upper layer of the liquid in the sedimentation separation tank is transferred back to the heavy-removal tower for re-distillation; the liquid discharged from the top of the finished product distillation tower is returned to the sedimentation separation tank, and the bottom liquid of the finished product distillation tower produces finished trifluoromethanesulfonyl fluoride from the bottom of the tower.

2. A special distillation method of trifluoromethanesulfonyl fluoride according to claim 1, characterized in that: The cooling and collecting pressure is 0~0.010MPa, and the temperature is controlled at -55~-105℃; the operating pressure of the light-removing tower is 0.310~0.330MPa, the exhaust temperature at the top of the tower is controlled at -8~-15℃, and the bottom temperature is 11~21℃; the operating pressure of the heavy-removing tower is 0.190~0.210MPa, the top temperature is 3~5℃, and the bottom temperature is 26~34℃.

3. A special distillation method of trifluoromethanesulfonyl fluoride according to claim 1, characterized in that: There are two sedimentation separation tanks, which are used alternately in sedimentation and discharging states. In the sedimentation state, the temperature in the sedimentation separation tank is controlled at -20~-30℃; in the discharging state, the jacket refrigerant is closed to increase the pressure in the sedimentation separation tank to 0.250~0.300MPa.

4. A special distillation method of trifluoromethanesulfonyl fluoride according to claim 1, characterized in that: The operating pressure of the finished product distillation tower is 0.190-0.210 MPa, the top temperature is 5-7°C, and the bottom temperature is 5-7°C.

5. A special distillation method of trifluoromethanesulfonyl fluoride according to claim 1, characterized in that: Light impurities include CO2 and SO2; heavy impurities include HF.

6. A special distillation device for trifluoromethanesulfonyl fluoride, used in the distillation method of trifluoromethanesulfonyl fluoride according to any one of claims 1 to 5, characterized in that: It includes a collecting tower, a light removal tower, a heavy removal tower, a sedimentation separation tank and a finished product distillation tower which are connected in sequence.

7. A rectification device for trifluoromethanesulfonyl fluoride according to claim 6, characterized in that: The collecting tower is provided with a collecting tower crude product feed inlet, a collecting tower liquid return inlet, a tower bottom liquefied material storage area, a collecting tower bottom discharge port and a collecting tower top venting port. The collecting tower top is provided with a condenser to condense the crude product gas using liquid nitrogen. The lightness removal tower is provided with a tower body feed port, a tower bottom discharge port and a tower top exhaust port; The deweighting tower is provided with a deweighting tower body feed inlet, a deweighting tower body return inlet, a deweighting tower top discharge inlet and a deweighting tower bottom discharge inlet; The sedimentation separation tank is provided with a feed inlet at the top of the sedimentation separation tank and a discharge outlet at the bottom of the sedimentation separation tank; The finished product distillation tower is provided with a finished product distillation tower body feed inlet, a finished product distillation tower top discharge port and a finished product distillation tower bottom discharge port; The bottom discharge port of the collecting tower is connected to the feed port of the light removal tower body, the bottom discharge port of the light removal tower is connected to the feed port of the heavy removal tower body, the return port of the heavy removal tower body is connected to the bottom discharge port of the sedimentation separation tank, the top discharge port of the heavy removal tower is connected to the feed port of the top of the sedimentation separation tank, the bottom discharge port of the sedimentation separation tank is connected to the feed port of the finished distillation tower body, and the top discharge port of the finished distillation tower is connected to the feed port of the top of the sedimentation separation tank.

8. A rectification device for trifluoromethanesulfonyl fluoride according to claim 6, characterized in that: The light-removal tower, heavy-removal tower and finished product distillation tower are all provided with a condensing heat exchanger at the top and a reboiler at the bottom.

9. A rectification device for trifluoromethanesulfonyl fluoride according to claim 6, characterized in that: A delivery pump is arranged between the collecting tower and the light-removing tower, one end of the delivery pump is connected to the discharge port at the bottom of the collecting tower, and the other end is respectively connected to the liquid return port of the collecting tower and the feed port of the tower body of the light-removing tower; the liquid level of the collecting tower is interlocked with the delivery pump for control, and when the liquid level is higher than the set value, the liquefied crude product is delivered to the feed port of the tower body of the light-removing tower; when the liquid level is lower than the set value, the liquefied crude product is returned to the liquid return port of the collecting tower and enters the collection tower circulation.

10. A rectification device for trifluoromethanesulfonyl fluoride according to claim 6, characterized in that: The light-removal tower, heavy-removal tower and finished product distillation tower are all packed towers.

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