A method for separating and directional conversion of perfluorofunctional monomers by-produced acyl fluoride

Abstract

The application discloses a method for separating and directionally converting perfluorinated functional monomers by-produced acyl fluoride, and belongs to the technical field of fluorine-containing fine chemical resource utilization. The application passes the gas containing COF2 and CF3COF into a molecular sieve adsorption tower for adsorption and purification, and refines the COF2 and CF3COF; further, a double-path directional conversion is adopted: the obtained COF2 is passed into a fluidized bed filled with CsF and Al2O3 catalysts to react to generate CF3O gamma -CF2 ‑ Cs + Then, HFPO is passed in to synthesize CF3OCF2CF2COF; the obtained CF3COF is reacted with SO3 to generate CF3C(O)OSO2F; then, a Zn(OSO2F)2 catalyst is added and HFPO is passed in to react, and CF2=CFOCF2SO3H is obtained through a thin film evaporator; the obtained CF3OCF2CF2COF is loaded on SiO2 microspheres, irradiated through a microwave reactor, and PMVE is obtained through gas condensation. Through the double-path directional conversion, the application realizes the directional synthesis of the functional monomer containing ionic groups.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of fluorine-containing fine chemical resource utilization, and particularly relates to a method for separating and directionally converting perfluorinated functional monomers from by-product acyl fluoride. BACKGROUND

[0002] Hexafluoropropylene oxide (HFPO) is a key intermediate in the synthesis of fluorine-containing polymers, and is widely used in the preparation of polyperfluoroether oil, fluororubber and other high value-added materials. However, the oxidation reaction of hexafluoropropylene (HFP) in its industrial production produces a large amount of carbonyl fluoride (COF2, 15-25%) and perfluoroacetyl fluoride (CF3COF, 20-30%), which are difficult to directly utilize due to their chemical inertness. In traditional processes, they are treated by neutralization with lye, resulting in waste of fluorine resources and high-pollution emissions. At the same time, perfluorovinyl ether (such as PMVE, PEVE) is a special fluorine-containing monomer with high demand in the fields of medical materials and proton exchange membranes, but its synthesis usually relies on expensive purified monomers (such as tetrafluoroethylene), resulting in high cost.

[0003] The prior art proposes to treat COF2 and CF3COF by two-stage alkali washing, which can achieve harmlessness, but consumes 2 tons of NaOH and produces 1.5 tons of fluorine-containing waste per ton of HFPO, which is poor in economy and environmental protection. The prior art uses pure CF3COF to copolymerize with tetrafluoroethylene to prepare perfluoroether, but does not solve the problem of utilization of COF2, and requires high-pressure reaction conditions (5 MPa), which is high in energy consumption. The by-product utilization technology reported in Chinese patent CN101817728B realizes the mixed copolymerization of COF2 / CF3COF, but has the problems of single functionality of the product, which cannot meet the demand for functional monomers in high-end fields such as proton exchange membranes, and the problem of deactivation of the catalyst silver chloride by the COF2 hydrolysis product HF in the mixed system.

[0004] In summary, the prior art mainly has the following technical problems: 1. uncontrollable product generation: the forced mixing of raw materials leads to the coexistence of PMVE / PEVE / PPVE three components, and the boiling points of which are not much different, resulting in high cost of rectification separation; 2. easy poisoning of catalyst: silver chloride is easily deactivated by the COF2 hydrolysis product HF in the mixed system, with a service life of less than 100 hours; 3. relatively single synthesis product: the product is only the general type of enol ether PMVE and PEVE, which cannot meet the demand for functional monomers in high-end fields such as proton exchange membranes. SUMMARY

[0005] To solve the problems in the prior art, the present application proposes a method for separating and directionally converting perfluorinated functional monomers from by-product acyl fluoride.

[0006] The method of the present application specifically relates to a deep separation method of carbonyl fluoride (COF2) and perfluoroacetyl fluoride (CF3COF) by-produced in the production of hexafluoropropylene oxide (HFPO), and a process of respectively directing the conversion of the by-products into perfluoromethyl vinyl ether (PMVE) and a functional monomer containing a sulfonic acid group perfluorovinyl ether. The present application breaks through the product component locking effect caused by the copolymerization of the mixed by-products (COF2+CF3COF) by innovatively separating the mixed by-products (COF2+CF3COF) with high efficiency and copolymerizing with HFPO; develops a special catalyst system resistant to hydrogen fluoride poisoning, improves the service life of the catalyst, and reduces the production cost; and realizes the directional synthesis of the functional monomer containing an ionic group through double-path directional conversion.

[0007] The technical solution of the present application is as follows:

[0008] The present application provides a method for separating and directionally converting perfluoro functional monomers from by-product acyl fluoride, which comprises the following steps:

[0009] 1) Molecular sieve adsorption deep separation: the HFPO production crude fraction column light component gas containing COF2 and CF3COF is introduced into a molecular sieve adsorption tower for adsorption; after the adsorption is completed, N2 is switched to purge, wherein the gas components not adsorbed are condensed and liquefied below-30℃ and then rectified to obtain CF3COF, and the adsorption tower is heated to 100-150℃ for desorption to obtain COF2;

[0010] 2) Double-path directional conversion:

[0011] Path 1: the COF2 obtained in step 1) is introduced into a fluidized bed loaded with γ-Al2O3 catalyst together with CsF, and a reaction is carried out at 90-110℃ under normal pressure to generate CF3O - Cs + Then HFPO is introduced to synthesize CF3OCF2CF2COF;

[0012] Path 2: the CF3COF obtained in step 1) is reacted with SO3 at-20--5℃ to generate CF3C(O)OSO2F; then Zn(OSO2F)2 catalyst is added, and HFPO is introduced according to a mass ratio of Zn(OSO2F)2:HFPO of 1:1.05-1.25, a reaction is carried out, and CF2=CFOCF2SO3H is obtained by thin film evaporator purification;

[0013] 3) Microwave-assisted cleavage: the obtained CF3OCF2CF2COF is loaded on SiO2 microspheres, irradiated by a microwave reactor, and PMVE is obtained by condensation of the cleavage gas.

[0014] Further, the crude fraction column light component gas of the present application is the light component gas obtained by separating the HFPO synthesis gas obtained by gas phase oxidation of hexafluoropropylene through a crude fraction column, which contains 20-40% COF2 and 20-30% CF3COF in terms of mass percentage.

[0015] According to a preferred scheme of the present application, the molecular sieve in step 1) is a lithium ion modified X-type molecular sieve, the adsorption temperature is 50-60℃, the pressure is 1.0 MPa, the space velocity is 0.5-1.5 h -1 .

[0016] According to a preferred scheme of the present application, in step 2) path 1, the molar ratio of COF2 to CsF is 1:2, and the fluidized bed catalyst space velocity is 0.2-1.0 h -1 , CF3O - Cs + The molar ratio of HFPO is 1:1.05-1.25.

[0017] According to a preferred scheme of the present application, in step 2) path 2, the molar ratio of CF3COF to SO3 is 1:1.05; the reaction temperature in path 2 is 60-70℃, and the reaction time is 1-3h; the operating conditions of the thin film evaporator are: temperature 70-90℃, vacuum degree 30-80kPa, and the purity of the obtained CF2=CFOCF2SO3H is ≥95%.

[0018] According to a preferred scheme of the present application, in step 3), the particle size of the SiO2 microspheres is 100 μm, and the loading rate of CF3OCF2CF2COF is 25%-35%.

[0019] According to a preferred scheme of the present application, in step 3), the frequency of the microwave reactor irradiation is 2.45 GHz, the power is 8kW, and the irradiation time is 4-10min. Further, in step 3), the temperature of the microwave cracking is 70-90℃, and the purity of the obtained PMVE is ≥99.7%.

[0020] According to a preferred scheme of the present application, the amount of Zn(OSO2F)2 used in step 2) path 2 is 1.0-2.0 mol% of the total mass of the reactants. The purity of the CF2=CFOCF2SO3H obtained in step 2) path 2 is ≥95%.

[0021] Compared with the prior art, the present application has at least the following beneficial effects:

[0022] 1. Controllable synthesis product: high-efficiency separation of COF2 / CF3COF (purity >98%) is achieved by LiX molecular sieve adsorption, solving the problem of component interference in mixed copolymerization.

[0023] 2. Improve product diversity: develop a new type of perfluorosulfonic acid vinyl ether (CF2=CFOCF2SO3H) with a purity of ≥95%, which is suitable for proton exchange membrane synthesis.

[0024] 3. Improve reaction efficiency and energy consumption: The energy consumption of microwave cracking is only 35% of that of traditional processes, and the time can be shortened to up to 10% of that of traditional processes. DETAILED DESCRIPTION

[0025] The present invention will be further described and illustrated below in conjunction with specific embodiments. The embodiments are merely illustrative of the present disclosure and do not limit its scope. The technical features of the various embodiments of the present invention may be combined accordingly, provided that there is no conflict between them.

[0026] The following example is a specific implementation process of the present invention, describing the method of separating by-product acyl fluoride and directional conversion of perfluorofunctional monomers of the present invention:

[0027] 1. Molecular sieve adsorption depth separation

[0028] The HFPO synthesis gas from the upstream hexafluoropropylene gas-phase oxidation process is separated by a coarse fractionation tower, which is a common equipment in the process and is used to remove the entrained solvent and residual oxygen in the HFPO synthesis gas. The light component gas (COF2 20-40%, CF3COF 20-30%) obtained from the coarse fractionation tower enters a vertical LiX molecular sieve adsorption tower (diameter 1.2 m, loading capacity 800 kg) for adsorption. The tower temperature is controlled at 50-60°C, the pressure is 1.0 MPa, and the gas space velocity is 0.5-1.5 h-1. -1 , lasting for 30 min, the COF2 adsorption rate can reach more than 99%.

[0029] Switch to N2 purge at a flow rate of 15-30 m³ / h. The remaining gas not adsorbed during the adsorption phase enters the condenser and liquefies at temperatures below -30°C. CF3COF is then purified by distillation to a purity exceeding 98.5%. This breaks through the limitations of mixed copolymerization and achieves a separation efficiency exceeding 98%.

[0030] After discharging the unadsorbed components, continue N2 purging at a flow rate of 15~30m³ / h, raise the temperature to 100~150℃ for desorption, and the extracted COF2 has a purity greater than 99.2% and a dew point ≤-70℃.

[0031] 2. Dual-path directional conversion

[0032] Route 1: Preparation of PMVE precursor from COF2

[0033] COF2 and gaseous CsF were introduced into a fluidized bed reactor at a molar ratio of 1:2. The reactor contained a γ-Al2O3 catalyst bed. The reaction temperature was 90-110°C, the pressure was atmospheric pressure, and the catalyst space velocity was 0.2-1.0 h -1 , generating CF3O - Cs +, and HFPO (molar ratio Zn(OSO2F)2:HFPO = 1 : 1.05~1.25) was introduced, and the temperature was raised to 65°C, and the mixture was kept for 2h to obtain sulfonic acid monomer CF2=CFOCF2SO3H, with purity of more than 95%. The crude product was introduced into a thin film evaporator (temperature 70~90°C, vacuum degree 30~80 kPa) to remove dimer impurities. - Cs + :HFPO=1:1.05~1.25), and the PMVE precursor CF3OCF2CF2COF was synthesized, with selectivity of more than 90%.

[0034] Path 2: Preparation of sulfonic acid monomer from CF3COF

[0035] CF3COF and liquid SO3 were introduced into a porcelain sulfonation kettle at a molar ratio of 1:1.05, the temperature was controlled at -20~-5°C to prevent explosive polymerization, and the reaction time was 40 min to obtain perfluoroacetyl fluorosulfonate (CF3C(O)OSO2F), with yield of more than 98.1%.

[0036] 1.5 mol% of Zn(OSO2F)2 catalyst was added, and HFPO (molar ratio Zn(OSO2F)2:HFPO = 1 : 1.05~1.25) was introduced, and the temperature was raised to 65°C, and the mixture was kept for 2h to obtain sulfonic acid monomer CF2=CFOCF2SO3H, with purity of more than 95%. The crude product was introduced into a thin film evaporator (temperature 70~90°C, vacuum degree 30~80 kPa) to remove dimer impurities.

[0037] 3. Microwave-assisted directional cleavage section

[0038] The PMVE precursor was loaded on SiO2 microspheres (particle size 100μm, loading rate 30%) and introduced into a continuous microwave cleavage reactor (2.45GHz), and the speed through the microwave cavity was 0.8m / min, the microwave power was 300W, the irradiation time was 4~10min, and the temperature was 70~90°C.

[0039] The cleavage gas was composed of PMVE 92.1% and CO2 6.5%, and PMVE product was obtained after condensation, with purity of more than 99.7%.

[0040] Example 1

[0041] 1. By-product separation

[0042] The HFPO production crude fraction column light component gas (containing COF230%, CF3COF 25%) was introduced into a vertical LiX molecular sieve adsorption column (diameter 1.2m, loading capacity 800kg). The column temperature was controlled at 55°C, the pressure was 1.0MPa, the airspeed was 1.0h -1 , and the COF2 adsorption rate reached 99.3% after 30 min of adsorption. The N2 purge (flow rate 20m³ / h) was switched, the temperature was raised to 120°C for desorption, and COF2 with purity of 99.5% and dew point of -72°C was collected. The column bottom gas was condensed and liquefied at -35°C, and CF3COF with purity of 98.7% was obtained by rectification.

[0043] 2. Directional conversion

[0044] Path 1 (PMVE synthesis):

[0045] COF2 and CsF were fed into a fluidized bed (γ-Al2O3 catalyst) at a molar ratio of 1:2 and reacted at 110°C under normal pressure (space velocity 0.5 h-1) to produce CF3O -1 - Cs + ; then HFPO was fed in (molar ratio 1:1.15) to obtain PMVE precursor CF3OCF2CF2COF with a selectivity of 91.2%.

[0046] Path 2 (sulfonic acid monomer synthesis):

[0047] CF3COF and liquid SO3 were fed at a ratio of 1:1.05 and reacted at -10°C for 40 min to obtain CF3C(O)OSO2F (yield 98.5%). 1.5 mol% Zn(OSO2F)2 catalyst was added, and HFPO was fed in (molar ratio 1:1.15) and reacted at 65°C for 2 h. The crude product was purified by a thin film evaporator (80°C, 50 kPa) to obtain CF2=CFOCF2SO3H with a purity of 95.2%.

[0048] 3. Microwave cracking

[0049] The PMVE precursor was loaded on SiO2 microspheres (loading rate 30%) and passed through a microwave reactor (2.45 GHz, 8 kW) at a speed of 0.8 m / min and irradiated for 6 min (85°C). After condensation of the cracking gas, PMVE with a purity of 99.7% and a yield of 94.1% was obtained.

[0050] Example 2

[0051] 1. By-product separation

[0052] As in Example 1, the adsorption tower was heated to 60°C, the desorption temperature was 150°C, and the N2 flow rate was 30 m3 / h. The purity of COF2 was 99.6%, and the purity of CF3COF was 99.0%.

[0053] 2. Directional conversion

[0054] Path 1: The ratio of HFPO was increased to 1:1.25, and the selectivity of PMVE precursor was 92.1%.

[0055] Path 2: The amount of catalyst Zn(OSO2F)2 was increased to 2.0 mol%, and the purity of sulfonic acid monomer was 96.3%.

[0056] 3. Microwave cracking

[0057] ​The irradiation time was extended to 10 min (70°C), and the PMVE purity was 99.6%, with dimer residue <0.1%.

[0058] Example 3

[0059] 1. By-product separation

[0060] The adsorption tower diameter was expanded to 1.5 m (loading capacity 1250 kg), with airspeed 1.5 h -1 , COF2adsorption rate 99.1%, separation efficiency 98.5%.

[0061] 2. Directional conversion

[0062] Path 1: using a fluidized bed with a diameter of 0.6 m, the PMVE precursor single batch yield reached 120 kg.

[0063] Path 2: 500 L enamel sulfonation kettle was used to feed CF3COF 200 kg, and the sulfonic acid monomer yield was 97.8%.

[0064] 3. Microwave cracking

[0065] The linear speed was increased to 1.0 m / min, and 1.2 tons of PMVE precursor could be processed per day, with energy consumption only 33% of the traditional process.

[0066] Comparative Example 1

[0067] The unseparated light component gas (COF230% + CF3COF 25%) was directly introduced into the polymerization kettle, AgCl catalyst (amount 1 mol%) was used, and HFPO was copolymerized under 5 MPa pressure. The product was analyzed by GC-MS, and PMVE was 45%, PEVE was 38%, and PPVE was 12% (three components coexist), the product needed to be separated by five-tower rectification, and the cost would increase by more than 300%; the catalyst was deactivated due to HF poisoning after 80 hours of operation, and the activity decreased by 82%.

[0068] Comparative Example 2

[0069] The PMVE precursor CF3OCF2CF2COF obtained in Example 1 was placed in a tube furnace and cracked at 160°C for 2 hours, and the cracking gas composition was PMVE 68.2%, CO2 28.5%, and dimer 3.3%; after condensation, the PMVE purity was only 85.3%, and needed to be purified by secondary rectification; the energy consumption was 2.9 times that of microwave cracking, and the time was 12 times longer.

[0070] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it cannot be understood as a limitation to the patent scope of the present application. For ordinary skilled in the art, several modifications and improvements can be made without departing from the concept of the present application, which shall all fall into the protection scope of the present application.

Claims

1. A method for separating and directing the conversion of perfluorinated functional monomers with by-product acyl fluorides, characterized in that, Comprise the following steps: 1) Molecular sieve adsorption depth separation: the COF2 and CF3COF containing crude fraction column light component gas into the molecular sieve adsorption tower adsorption, after adsorption is completed, switch N2purge, wherein the gas components not adsorbed are condensed and liquefied below-30 DEG C, and then rectified to obtain CF3COF, the adsorption tower is heated to 100~150 DEG C desorption, and COF2 is obtained; the crude fraction column light component gas is the light component gas obtained by separating the HFPO synthesis gas obtained by vapor phase oxidation of hexafluoropropylene by a crude fraction column, containing 20~40% COF2 and 20~30% CF3COF by mass percentage; the molecular sieve is lithium ion modified X type molecular sieve; 2) Double path directional conversion: Path 1: The COF2 obtained in step 1) is passed with CsF into a reactor packed with Path 2: CF3COF obtained in step 1) is reacted with SO3 at-20~-5 DEG C to generate CF3C(O)OSO2F; then Zn(OSO2F)2 catalyst is added, and HFPO is passed in according to the mass ratio of Zn(OSO2F)2:HFPO of 1:1.05~1.25, and CF2=CFOCF2SO3H is obtained by reaction and thin film evaporator purification; - a fluidized bed of AI2O3 catalyst, 90-110°C, atmospheric pressure, to form CF3O - Cs + HFPO is then passed in, to synthesize CF3OCF2CF2COF; 3) Microwave assisted cleavage: the obtained CF3OCF2CF2COF is loaded on SiO2 microspheres, and irradiated by a microwave reactor, and PMVE is obtained by condensing the cleavage gas. In step 2) path 2, the molar ratio of CF3COF to SO3 is 1:1.05; the reaction temperature in path 2 is 60-70 DEG C, and the reaction time is 1-3h; the operating conditions of the thin film evaporator are: temperature 70~90 DEG C, vacuum degree 30~80 kPa, and the purity of the obtained CF2=CFOCF2SO3H is ≥95%.

2. The method of claim 1, wherein, The adsorption temperature in step 1) is 50-60°C, the pressure is 1.0 MPa, and the space velocity is 0.5-1.5 h -1 .

3. The method of claim 1, wherein, Step 2) in Path 1, the molar ratio of COF2to CsF is 1:2, the fluidized bed catalyst space velocity is 0.2~1.0 h -1 , CF3O - Cs + The molar ratio of Cs to HFPO is 1:1.05~1.

25.

4. The method of claim 1, wherein, In step 3), the frequency of microwave reactor irradiation is 2.45 GHz, the power is 8kW, and the irradiation time is 4-10min.

5. The method of claim 1, wherein, In step 3), the particle size of the SiO2microspheres is 100 In step 3), the temperature of microwave cleavage is 70~90 DEG C, and the purity of the obtained PMVE is ≥99.7%. m, the loading of CF3OCF2CF2COF is 25%-35%.

6. The method of claim 1, wherein, The amount of Zn(OSO2F)2 used in step 2) path 2 is 1.0~2.0 mol% of the total mass of the reactants.

7. The method of claim 1, wherein, The purity of CF2=CFOCF2SO3H obtained in step 2) path 2 is ≥95%.

8. The method of claim 1, wherein, ​ 9. The method of claim 1, wherein, ​