Method for efficiently preparing perfluorotripropylamine

Abstract

The invention provides a method for efficiently preparing perfluorotripropylamine, and belongs to the field of organic fluorine compound preparation. A two-step strategy of'continuous gas phase pre-fluorination-electrochemical deep fluorination 'is adopted. Tripropylamine and F2 / N2 gas are catalyzed by gradient pore cobalt oxide at high temperature and normal pressure, rapid pre-fluorination is carried out, and crude PFTPA is recovered. And dissolving the crude PFTPA and anhydrous HF, carrying out deep fluorination by adopting an electrolytic bath, and then carrying out alkali washing, alcohol refluorination and rectification to obtain the perfluorotripropylamine. The method is high in process safety, excellent in environmental protection property, simplified in equipment and suitable for industrial production.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of organic fluorine compound preparation, and particularly relates to a method for efficiently preparing perfluorotripropylamine. BACKGROUND

[0002] Perfluorotripropylamine (C9F 21 N, CAS No. 338-83-0) is a colorless, transparent, non-volatile, highly chemically inert and thermally stable perfluorinated organic amine liquid. Its boiling point is about 125-135 DEG C, has very low surface tension, and has high resistance to strong acid, strong base and strong oxidizing agent. It has excellent dielectric properties and lubricity, is often used as a special fluorinated liquid in high-end fields such as electronics, instruments, semiconductors, data center cooling, and is used in the form of perfluorocarbon emulsion for blood replacement and tissue perfusion in the medical field.

[0003] At present, the mainstream preparation route includes:

[0004] Continuous gas phase fluorination method: tripropylamine vapor and F2 / N2 mixed gas are introduced into a tubular reactor filled with oxide catalyst (such as cobalt, nickel, aluminum) for rapid fluorination, and then washed with alkali, washed with water and purified by rectification to obtain crude product. By accurately controlling the volume fraction of fluorine gas (20-35%), the reaction temperature (180-280 DEG C) and the short residence time (5-10 seconds), the replacement of C-H bond can be maximized, the C-C bond rupture can be reduced, and the process safety can be improved. The purity of the typical crude product can reach 97-98%, and the yield is about 68-75%.

[0005] Electrochemical fluorination (ECF) method: this method uses anhydrous HF as a solvent, and tripropylamine is treated in an electrolytic cell with a voltage (6-13V) to ionize HF and generate highly active F- for step-by-step fluorination. The advantages include relatively simple equipment, mild operating conditions, and suitability for continuous production; but the purity of the crude product is usually only 65-70%, which needs subsequent alkali-alcohol washing and rectification purification. At present, this method is applied in many enterprises in China, and the purification process is continuously improved to improve the quality of the finished product.

[0006] Although the above two methods have their own advantages, there are still many deficiencies:

[0007] In the continuous gas phase method, the high activity of F2 brings the risk of explosion / corrosion, and the control of temperature gradient and C-C bond rupture depends on precise equipment and strict process;

[0008] Although the electrochemical method has lower equipment requirements, it has the problems of HF corrosion, high impurities and low purity, and needs to further improve the product quality in the post-treatment stage;

[0009] The purity, ratio, electrolysis voltage, current density, temperature and other parameters of the raw materials tripropylamine and anhydrous HF have a significant influence on the final purity and yield.

[0010] With the increasing requirements of application fields (such as electronic cooling, medical emulsion) on the purity of PFTPA, impurities (PFAS residues), environmental regulations (European PFAS ban, etc.), the industry urgently needs to develop a preparation scheme with high yield, high purity, low cost and environmental protection. SUMMARY

[0011] Therefore, the application provides an optimized preparation method of perfluoroamine.

[0012] To achieve this purpose, the application adopts the following technical solutions:

[0013] A method for efficiently preparing perfluorotripropylamine, comprising the following steps:

[0014] Step A: continuous gas phase fluorination pretreatment:

[0015] Tripropylamine 50-100 parts;

[0016] Fluorine gas (F2) and nitrogen mixed gas, F2 volume fraction 20-35%, molar ratio 10-16:1 (F2: tripropylamine) is passed in;

[0017] Catalyst: gradient porosity cobalt oxide 10-30 parts, particle size 2-5 mm;

[0018] The temperature of the tubular reactor is set, the reaction residence time is 5-10 seconds, and the pressure is maintained at normal pressure or 0-0.1 MPa;

[0019] The pure product is washed with 20 parts of KOH aqueous solution, then washed with 50 parts of deionized water, dried, and then low boiling impurities are removed by rectification to recover crude PFTPA;

[0020] Step B (electrochemical deep fluorination):

[0021] Dissolve the crude PFTPA and anhydrous HF in the electrolytic cell according to the mass ratio;

[0022] The electrolytic cell is set to 3-4 stages in series, the voltage of each stage is 6-13V, and the total current density is 0.025-0.033A / cm 2 ;

[0023] The temperature of the electrolytic cell is controlled in stages at -5 to 0℃, and the electrolysis time is 5-15 days;

[0024] After each stage of electrolysis, slowly release the gas, absorb the acidic gas in a reactor containing 5-15 parts of triethylamine, and then enter the condensation tower for treatment with chilled ethylene glycol solution;

[0025] Step C (post-treatment and purification):

[0026] After electrolysis, add 30-50 parts of NaHCO3 aqueous solution to the electrolyte and wash 3 times, then separate after standing and layering;

[0027] Alkaline fluorination of the organic phase with 30 parts of 30wt% KOH / ethanol solution for 30-60 minutes, neutralization of unreacted residues;

[0028] Finally, atmospheric distillation to a boiling point of 230-250°C to obtain PFTPA with a purity of ≥99%.

[0029] As a preferred embodiment of the present application, the molar ratio of F2: tripropylamine is 10-16:1.

[0030] As a preferred embodiment of the present application, the preparation method of the gradient-pore cobalt oxide is:

[0031] (1) Basic mesoporous pore formation: add cobalt oxide precursor and multi-walled carbon nanotubes to a cobalt nitrate solution with a concentration of 0.5-1M, with the multi-walled carbon nanotubes accounting for 0.5-1wt% of the mass of the cobalt oxide precursor, ultrasonically disperse, and then extrude 2-5mm cylindrical particles through an extruder, dry, and then pass argon through a tube furnace to calcine and remove the carbon nanotubes, forming 50-100nm initial mesoporous channels;

[0032] (2) Gradient modification and gas expansion: use a layer-by-layer impregnation method to gradient-dope the particles obtained in step (1), with the impregnation solution being a mixed solution of lanthanum nitrate and nickel nitrate, wherein the lanthanum nitrate concentration is 0.1-0.5M, the nickel nitrate concentration is 0.2-1M, and the inner layer concentration is higher than the outer layer; then place the particles in a high-pressure reaction kettle and pass in a mixed gas of carbon dioxide, trimethylboron, triethylphosphorus, and argon with a volume ratio of 1-3:0.4-1:0.2-0.5:7-10, under the conditions of a pressure of 0.1-0.2MPa and a temperature of 240-350°C for 2-5 hours, to form gradient pores and a boron-based and phosphorus-based functional group composite modification layer on the pore surface; thus obtaining the gradient-pore cobalt oxide.

[0033] As a preferred embodiment of the present application, the temperature of the tube reactor is 180-280°C.

[0034] As a preferred embodiment of the present application, the concentration of the KOH aqueous solution is 15-20wt%.

[0035] As a preferred embodiment of the present application, the mass ratio of crude PFTPA to anhydrous HF is 1:8-10.

[0036] As a preferred embodiment of the present application, the frozen ethylene hydride solution has a temperature of -30 to -40℃.

[0037] As a preferred embodiment of the present application, the NaHCO3 aqueous solution has a concentration of 3-5wt%.

[0038] Reaction mechanism

[0039] Gradient doping-gas expansion synergistic regulation mechanism: high concentration of La in the inner layer 3+ , Ni 2 Oxygen vacancy structure by lattice distortion induced Co3O4 formation, provide active sites for gas expansion; CO2 in the mixed gas preferentially etches the oxygen vacancy region, combined with the selective deposition of B and P species, forming a gradient pore from inside to outside (200→100nm) with gradually decreasing pore size, realizing mass transfer-reaction matching.

[0040] B-P-O modification layer electronic regulation mechanism: B and P atoms generated by decomposition of trimethylboron and triethylphosphorus combine with O on the pore surface to form a B-P-O ternary structure, which reduces the d-band center energy level of Co active sites through electron transfer, enhances the adsorption and activation ability of C-F bond, and reduces the bond dissociation energy from 120kJ / mol to 85kJ / mol.

[0041] In summary, the present application has the following advantages:

[0042] 1) The continuous gasification stage realizes efficient pre-fluorination, improving the overall raw material conversion rate.

[0043] 2) The electrochemical stage completely processes residual C-H bonds that are difficult to further fluorinate in the gas phase, improving purity and yield.

[0044] 3) The process combination disperses the demand for harsh conditions, improves safety, and reduces equipment investment and operating costs.

[0045] 4) The single-pass conversion rate and selectivity of perfluorotripropylamine are improved due to the gradient pore reducing mass transfer resistance and B-P modification enhancing active site utilization. Gradient porosity inhibits fluoride carbon deposition, B-P-O layer resists fluorine corrosion, and the service life of the catalyst is extended. DETAILED DESCRIPTION

[0046] The technical solutions of the present application will be further described below through specific embodiments. Those skilled in the art should understand that the specific embodiments are only to help understand the present application and should not be regarded as a specific limitation of the present application. If not specifically indicated, the technical means used in the following examples are conventional means well known to those skilled in the art, and the raw materials used are conventional commercial goods.

[0047] Example 1

[0048] Raw materials and parameters:

[0049] Tripropylamine: 50 g

[0050] Fluorine gas mixed with nitrogen gas (F2 volume fraction 20%), F2: tripropylamine molar ratio 10:1

[0051] Gradient-pore cobalt oxide catalyst: 10 g (particle size 2 mm)

[0052] Crude PFTPA: anhydrous HF mass ratio 1:8

[0053] NaHCO3 aqueous solution: 30 g (concentration 3 wt%)

[0054] Step A (continuous gas-phase fluorination pretreatment):

[0055] 50 g of tripropylamine was introduced into a tubular reactor while introducing a mixed gas with a F2 volume fraction of 20% (F2: tripropylamine molar ratio 10:1), and the catalyst was 10 g of gradient-pore cobalt oxide (particle size 2 mm).

[0056] The temperature of the tubular reactor was set to 180°C, the reaction residence time was 5 seconds, and the pressure was normal pressure (0 MPa).

[0057] The product was washed with 20 g of 15 wt% KOH aqueous solution, 50 g of deionized water, dried, and then rectified to remove low-boiling impurities to recover crude PFTPA.

[0058] Step B (electrochemical deep fluorination):

[0059] Crude PFTPA and anhydrous HF were dissolved in a 3-stage series electrolytic cell at a mass ratio of 1:8.

[0060] The voltage of each stage was 6 V, and the total current density was 0.025 A / cm 2 The temperature was controlled at -5°C, and the electrolysis time was 5 days.

[0061] The gas released by each stage was absorbed by a reaction kettle containing 5 g of triethylamine to remove acidic gas, and then treated by condensation with -40°C frozen ethyl hydrazine solution.

[0062] Step C (post-treatment and purification):

[0063] The electrolyte was washed with 30 g of 3 wt% NaHCO3 aqueous solution for 3 times, and the organic phase was separated after standing and layering.

[0064] The organic phase was refluxed with 30 g of 30 wt% KOH / ethanol solution for 30 minutes, and the residue was neutralized.

[0065] Normal pressure rectification was performed to a boiling point of 230°C to obtain perfluorotripropylamine (PFTPA) with a purity of ≥99%.

[0066] Gradient pore cobalt oxide preparation:

[0067] Basic mesoporous pore: cobalt oxide precursor plus 0.5wt% multi-walled carbon nanotubes, dispersed in 0.5M cobalt nitrate solution, extruded into 2mm particles, dried and calcined in argon to form 50nm mesopores.

[0068] Gradient modification: layer-by-layer impregnation of 0.1M lanthanum nitrate and 0.2M nickel nitrate (inner layer concentration higher than outer layer), mixed gas (CO2: trimethylboron: triethylphosphorus: argon = 1:0.4:0.2:7) introduced into the autoclave, 0.1MPa, 240℃ for 2 hours, forming gradient pores.

[0069] Example 2

[0070] Raw materials and parameters:

[0071] Tripropylamine: 65g

[0072] Fluorine gas and nitrogen mixed gas (F2 volume fraction 25%), F2: tripropylamine molar ratio 12:1

[0073] Gradient pore cobalt oxide catalyst: 17g (particle size 3mm)

[0074] Crude PFTPA and anhydrous HF mass ratio: 1:8.5

[0075] NaHCO3 aqueous solution: 35g (concentration 3.5wt%)

[0076] Step A:

[0077] Reactor temperature 210℃, residence time 7 seconds, pressure 0.03MPa, KOH aqueous solution concentration 17wt%, the rest same as Example 1.

[0078] Step B:

[0079] 4-stage electrolytic cell (first 3 stages), voltage per stage 8V, total current density 0.027A / cm 2 , temperature -3℃, electrolysis time 8 days.

[0080] Acid gas absorption with 8g triethylamine, frozen hydrazine solution temperature -37℃.

[0081] Step C:

[0082] Reflux time 40 minutes, rectification boiling point 238℃, the rest same as Example 1.

[0083] Gradient pore cobalt oxide preparation:

[0084] Multi-walled carbon nanotubes accounted for 0.7wt%, cobalt nitrate solution concentration 0.7M, mesopores 70nm after calcination.

[0085] The impregnation solution is 0.3M lanthanum nitrate and 0.5M nickel nitrate, the mixed gas ratio is 1.5:0.6:0.3:8, the pressure is 0.15MPa, the temperature is 280℃, and the holding time is 3 hours, to form a gradient pore.

[0086] Example 3

[0087] Raw materials and parameters:

[0088] Tripropylamine: 85g

[0089] Fluorine gas mixed with nitrogen gas (F2volume fraction 30%), F2: tripropylamine molar ratio 14:1

[0090] Gradient-pore cobalt oxide catalyst: 24g (particle size 4mm)

[0091] Crude PFTPA and anhydrous HF mass ratio: 1:9.5

[0092] NaHCO3aqueous solution: 45g (concentration 4.5wt%)

[0093] Step A:

[0094] Reactor temperature 250℃, residence time 8 seconds, pressure 0.07MPa, KOH aqueous solution concentration 18wt%.

[0095] Step B:

[0096] 4-stage series electrolytic cell, each stage voltage 11V, total current density 0.031A / cm 2 , temperature -2℃, electrolysis time 12 days.

[0097] Acid gas absorption uses 12g triethylamine, and the refrigerated hydrazine solution temperature is -33℃.

[0098] Step C:

[0099] Reflux time 50 minutes, rectification boiling point 245℃.

[0100] Gradient-pore cobalt oxide preparation:

[0101] Multi-walled carbon nanotube proportion 0.8wt%, cobalt nitrate solution concentration 0.8M, mesopore 85nm after calcination.

[0102] The impregnation solution is 0.4M lanthanum nitrate and 0.8M nickel nitrate, the mixed gas ratio is 2.5:0.8:0.4:9, the pressure is 0.18MPa, the temperature is 320℃, and the holding time is 4 hours.

[0103] Example 4

[0104] Raw materials and parameters:

[0105] Tripropylamine: 100g

[0106] Fluorine gas mixed with nitrogen gas (F2 volume fraction 35%), F2: tripropylamine molar ratio 16:1

[0107] Gradient pore cobalt oxide catalyst: 30 g (particle size 5 mm)

[0108] Crude PFTPA and anhydrous HF mass ratio: 1:10

[0109] NaHCO3 aqueous solution: 50 g (concentration 5 wt%)

[0110] Step A:

[0111] Reactor temperature 280°C, residence time 10 seconds, pressure 0.1 MPa, KOH aqueous solution concentration 20 wt%.

[0112] Step B:

[0113] 4-stage series electrolytic cell, each stage voltage 13 V, total current density 0.033 A / cm 2 , temperature 0°C, electrolysis time 15 days.

[0114] Acid gas absorption with 15 g triethylamine, frozen hydrazine solution temperature -30°C.

[0115] Step C:

[0116] Reflux time 60 minutes, rectification boiling point 250°C.

[0117] Gradient pore cobalt oxide preparation:

[0118] Multi-walled carbon nanotube proportion 1 wt%, cobalt nitrate solution concentration 1 M, mesopore 100 nm after calcination.

[0119] Impregnation solution 0.5 M lanthanum nitrate, 1 M nickel nitrate, mixed gas ratio 3:1:0.5:10, 0.2 MPa, 350°C for 5 hours.

[0120] Comparative Example 1

[0121] Raw materials and parameters:

[0122] Tripropylamine: 50 g

[0123] Fluorine gas mixed with nitrogen gas (F2 volume fraction 20%), F2: tripropylamine molar ratio 10:1

[0124] Cobalt oxide catalyst: 10 g (particle size 2 mm)

[0125] Crude PFTPA and anhydrous HF mass ratio: 1:8

[0126] NaHCO3 aqueous solution: 30 g (concentration 3 wt%)

[0127] Step A (continuous gas phase fluorination pretreatment) :

[0128] 50 g of tripropylamine was fed into a tubular reactor while a mixed gas of F2 with a volume fraction of 20% (F2: tripropylamine molar ratio of 10:1) was fed in, and the catalyst was 10 g of gradient-pore cobalt oxide (particle size of 2 mm).

[0129] The temperature of the tubular reactor was set to 180°C, the reaction residence time was 5 seconds, and the pressure was normal pressure (0 MPa).

[0130] The product was washed with 20 g of 15 wt% KOH aqueous solution, washed with 50 g of deionized water, dried, and then rectified to remove low-boiling impurities, and crude PFTPA was recovered.

[0131] Step B (electrochemical deep fluorination) :

[0132] The crude PFTPA was dissolved in a 3-stage series electrolytic cell in a mass ratio of 1:8 with anhydrous HF.

[0133] The voltage of each stage was 6 V, and the total current density was 0.025 A / cm 2 , the temperature was controlled at -5°C, and the electrolysis time was 5 days.

[0134] The gas released by each stage was absorbed by a reaction kettle containing 5 g of triethylamine to remove acidic gas, and then treated by condensation with -40°C frozen ethyl hydrazine solution.

[0135] Step C (post-treatment and purification) :

[0136] The electrolyte was washed with 30 g of 3 wt% NaHCO3 aqueous solution 3 times, and after standing and layering, the organic phase was separated.

[0137] The organic phase was refluxed with 30 g of 30 wt% KOH / ethanol solution for 30 minutes, and the residue was neutralized.

[0138] Normal pressure rectification was performed to a boiling point of 230°C, and pure perfluorotripropylamine (PFTPA) with a purity of ≥99% was obtained.

[0139] Comparative Example 2

[0140] Raw materials and parameters:

[0141] Tripropylamine: 50 g

[0142] Fluorine gas and nitrogen mixed gas (F2 volume fraction of 20%), F2: tripropylamine molar ratio of 10:1

[0143] Gradient-pore cobalt oxide catalyst: 10 g (particle size of 2 mm)

[0144] Mass ratio of crude PFTPA to anhydrous HF: 1:8

[0145] NaHCO3 aqueous solution: 30g (concentration 3wt%)

[0146] Step A (continuous gas phase fluorination pretreatment):

[0147] 50g of tripropylamine was introduced into a tubular reactor, and at the same time, a mixed gas with a volume fraction of 20% of F2 (the molar ratio of F2 to tripropylamine was 10:1) was introduced. The catalyst was 10g of gradient porous cobalt oxide (particle size 2mm).

[0148] The temperature of the tubular reactor was set at 180° C., the reaction residence time was 5 seconds, and the pressure was normal pressure (0 MPa).

[0149] The product was alkaline washed with 20 g of 15 wt% KOH aqueous solution and 50 g of deionized water, dried and then distilled to remove low-boiling impurities to recover crude PFTPA.

[0150] Step B (electrochemical deep fluorination):

[0151] Crude PFTPA and anhydrous HF were dissolved in a three-stage series electrolytic cell at a mass ratio of 1:8.

[0152] Each level voltage is 6V, and the total current density is 0.025A / cm 2 , the temperature was controlled at -5°C and the electrolysis time was 5 days.

[0153] The gas released at each stage passes through a reactor containing 5g of triethylamine to absorb the acidic gas, and is then condensed with -40℃ frozen ethylhydrazine liquid.

[0154] Step C (post-treatment and purification):

[0155] The electrolyte was washed three times with 30 g of 3 wt% NaHCO 3 aqueous solution, and the organic phase was separated after standing and stratification.

[0156] The organic phase was refluxed with 30 g of 30 wt% KOH / ethanol solution for 30 minutes to neutralize the residue.

[0157] Distill at atmospheric pressure to a boiling point of 230°C to obtain perfluorotripropylamine (PFTPA) with a purity of ≥99%.

[0158] Preparation of gradient porosity cobalt oxide:

[0159] Basic mesopore formation: Cobalt oxide precursor is added with 0.5wt% multi-walled carbon nanotubes, dispersed in 0.5M cobalt nitrate solution, extruded into 2mm particles, dried and calcined in argon to form 50nm mesopores.

[0160] Gradient modification: 0.1M lanthanum nitrate and 0.2M nickel nitrate were impregnated layer by layer (the concentration of the inner layer was higher than that of the outer layer), and a mixed gas (CO2: triethyl phosphine: argon = 1:0.2:7) was introduced into the autoclave at 0.1MPa and 240℃ for 2 hours to form gradient pores.

[0161] Comparative Example 3

[0162] Raw materials and parameters:

[0163] Tripropylamine: 50 g

[0164] Fluorine gas mixed with nitrogen gas (F2volume fraction 20%), F2: tripropylamine molar ratio 10:1

[0165] Gradient-pore cobalt oxide catalyst: 10 g (particle size 2 mm)

[0166] Crude PFTPA: anhydrous HF mass ratio 1:8

[0167] NaHCO3aqueous solution: 30 g (concentration 3 wt%)

[0168] Step A (continuous gas-phase fluorination pretreatment):

[0169] 50 g of tripropylamine was introduced into a tubular reactor while introducing a mixed gas with a F2volume fraction of 20% (F2: tripropylamine molar ratio 10:1), and the catalyst was 10 g of gradient-pore cobalt oxide (particle size 2 mm).

[0170] The temperature of the tubular reactor was set to 180°C, the reaction residence time was 5 seconds, and the pressure was atmospheric pressure (0 MPa).

[0171] The product was washed with 20 g of 15 wt% KOH aqueous solution, 50 g of deionized water, dried, and then rectified to remove low-boiling impurities to recover crude PFTPA.

[0172] Step B (electrochemical deep fluorination):

[0173] Crude PFTPA and anhydrous HF were dissolved in a 3-stage series electrolytic cell at a mass ratio of 1:8.

[0174] The voltage of each stage was 6 V, and the total current density was 0.025 A / cm 2 The temperature was controlled at -5°C, and the electrolysis time was 5 days.

[0175] The gas released from each stage was absorbed by a reaction kettle containing 5 g of triethylamine to remove acidic gas, and then treated by condensation with ethylamine liquid at -40°C.

[0176] Step C (post-treatment and purification):

[0177] The electrolyte was washed with 30 g of 3 wt% NaHCO3aqueous solution for 3 times, and the organic phase was separated after standing and layering.

[0178] The organic phase was refluxed with 30 g of 30 wt% KOH / ethanol solution for 30 minutes, and the residue was neutralized.

[0179] Normal pressure rectification to boiling point 230°C, purity ≥99% perfluorotripropylamine (PFTPA) is obtained.

[0180] Gradient pore cobalt oxide preparation:

[0181] Basic mesoporous pore: cobalt oxide precursor + 0.5wt% multi-walled carbon nanotubes, dispersed in 0.5M cobalt nitrate solution, extruded into 2mm particles, dried and calcined with argon to form 50nm mesopores.

[0182] Gradient modification: layer-by-layer impregnation of 0.1M lanthanum nitrate, 0.2M nickel nitrate (inner layer concentration higher than outer layer), mixed gas (CO2: trimethylboron: argon = 1:0.4:7) is introduced into the autoclave, 0.1MPa, 240°C for 2 hours, forming gradient pores.

[0183] Test method:

[0184] 1. GC-MS analysis (content and impurity analysis)

[0185] Instrument and conditions: gas chromatography-mass spectrometry (such as Agilent 7250 GC-QTOF or conventional GC-MS)

[0186] Sample pretreatment: direct injection or extraction and concentration with dichloromethane

[0187] Quantitative basis: determine the relationship between PFTPA peak area and mass concentration by standard curve; detection limit and quantitative limit refer to PFAS standard method of SJTU laboratory

[0188] Purpose: quantify target product content and evaluate non-PFTPA impurities (such as partially fluorinated or unreacted substances)

[0189] 2. 19 F-NMR structure confirmation and purity verification

[0190] Instrument: desktop 19 FNMR (Thermo Scientific picoSpin-45 / 80)

[0191] Standard and conditions: take 30-40μL sample, add 1% v / v hexafluorobenzene as internal standard, 90° pulse, sampling time 1000ms, cycle delay 10s

[0192] Purpose: confirm perfluoro structure; detect signals outside δ ~ -200…-150ppm caused by residual C-H

[0193] Test results:

[0194]

[0195]

[0196] The content described in the specification is merely a list of forms of the inventive concept, and the protection scope of the present application should not be regarded as being limited to the specific forms stated in the embodiments.

Claims

1. A method for efficiently preparing perfluorotripropylamine, characterized in that: The steps include: Step A: Continuous gas phase fluorination pretreatment: 50–100 parts by mass of tripropylamine; A mixture of fluorine and nitrogen, with a fluorine volume fraction of 20-35%, is introduced at a molar ratio of fluorine to tripropylamine of 10-16:1; The catalyst is 10–30 parts by mass of gradient porosity cobalt oxide with a particle size of 2–5 mm; Set the temperature of the tubular reactor, the reaction residence time is 5–10 seconds, and the pressure is maintained at atmospheric pressure or 0–0.1 MPa; The net product was washed with 20 parts by mass of KOH aqueous solution, then washed with 50 parts by mass of deionized water, dried, and then distilled to remove low-boiling impurities to recover crude PFTPA; Step B: Electrochemical deep fluorination: Dissolve crude PFTPA and anhydrous HF in an electrolytic cell; The electrolytic cell is set to 3–4 stages in series, with a voltage of 6–13 V per stage and a total current density of 0.025–0.033 A / cm 2 ; The electrolytic cell temperature is controlled in stages between -5 and 0°C, and the electrolysis time is 5–15 days; After each stage of electrolysis, the gas is slowly released and passed through a reactor containing 5-15 parts by mass of triethylamine to absorb the acidic gas, and then enters a condensation tower to be treated with refrigerated ethylhydrazine solution; Step C post-processing and purification: After the electrolysis is completed, 30–50 parts by mass of NaHCO3 aqueous solution is added to the electrolyte to wash three times, and the electrolyte is allowed to stand for stratification before separation; The organic phase was alkali-refluorinated by reflux with 30 parts of 30 wt% KOH / ethanol solution for 30–60 minutes to neutralize the unreacted residue; Finally, it was distilled at atmospheric pressure to a boiling point of 230–250°C to obtain PFTPA with a purity of ≥99%; The gradient porosity cobalt oxide is prepared by ultrasonically dispersing a cobalt oxide precursor, multi-walled carbon nanotubes, and a cobalt nitrate solution, drying and calcining the solution, and then immersing the solution in a mixed solution of lanthanum nitrate and nickel nitrate. The solution is then placed in a high-pressure reactor and heated by introducing a mixed gas of carbon dioxide, trimethylboron, triethylphosphine, and argon.

2. The method for efficiently preparing perfluorotripropylamine according to claim 1, wherein: The molar ratio of fluorine gas to tripropylamine is 10-16:

1.

3. The method for efficiently preparing perfluorotripropylamine according to claim 1, wherein: The preparation method of the gradient porosity cobalt oxide: (1) Basic mesoporous pore formation: a cobalt oxide precursor and multi-walled carbon nanotubes are added to a cobalt nitrate solution with a concentration of 0.5-1 M, wherein the multi-walled carbon nanotubes account for 0.5-1 wt% of the mass of the cobalt oxide precursor. After ultrasonic dispersion, 2-5 mm cylindrical particles are extruded through an extruder. After drying, argon gas is introduced into a tube furnace and calcined to remove the carbon nanotubes, forming an initial mesoporous channel of 50-100 nm. (2) Gradient modification and gas pore expansion: The particles obtained in step (1) are gradient doped by a layer-by-layer impregnation method, wherein the impregnation solution is a mixed solution of lanthanum nitrate and nickel nitrate, wherein the concentration of lanthanum nitrate is 0.1-0.5M, the concentration of nickel nitrate is 0.2-1M, and the concentration of the inner layer is higher than that of the outer layer; the particles are then placed in a high-pressure reactor, and a mixed gas of carbon dioxide, trimethyl boron, triethyl phosphine and argon with a volume ratio of 1-3:0.4-1:0.2-0.5:7-10 is introduced, and the mixture is kept warm for 2-5 hours at a pressure of 0.1-0.2MPa and a temperature of 240-350°C to form gradient pores, and a composite modification layer of boron-based and phosphorus-based functional groups is formed on the surface of the pores; the gradient porous cobalt oxide is obtained.

4. The method for efficiently preparing perfluorotripropylamine according to claim 1, wherein: The tubular reactor temperature was 180-280°C.

5. The method for efficiently preparing perfluorotripropylamine according to claim 1, wherein: The concentration of the KOH aqueous solution is 15-20 wt%.

6. The method for efficiently preparing perfluorotripropylamine according to claim 1, wherein: The mass ratio of the crude PFTPA to anhydrous HF is 1:8-10.

7. The method for efficiently preparing perfluorotripropylamine according to claim 1, wherein: The temperature of the frozen ethylhydrazine solution is -30 to -40°C.

8. The method for efficiently preparing perfluorotripropylamine according to claim 1, wherein: The concentration of the NaHCO 3 aqueous solution is 3-5 wt %.

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