JP3778298B2 - Method for producing hexafluoropropene - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a production method (especially a multistage production method) of hexafluoropropene which is industrially important as a monomer of a fluorine-containing polymer material.
[0002]
[Prior art]
As a method for producing hexafluoropropene, a method by thermal decomposition of tetrafluoroethylene is known. However, in this production method, perfluorobutene and perfluoroisobutene are inevitably by-produced in addition to the target hexafluoropropene. Perfluoroisobutene in these by-products is very toxic, and it is very expensive to decompose and remove it.
[0003]
As another method for obtaining hexafluoropropene, a production method for simultaneously obtaining tetrafluoroethylene and hexafluoropropene by thermal decomposition of chlorodifluoromethane is known. However, even in this case, as in the above-described method, the production of perfluoroisobutene is unavoidable, which is economically undesirable.
[0004]
Moreover, although each said manufacturing method is shown by US Patent 3873630, 2970176, 3459818, 2758138, 3306940, since all are pyrolyzed at high temperature, expensive metal materials Therefore, it is not economical in this respect.
[0005]
[Problems to be solved by the invention]
The object of the present invention is to produce hexafluoropropene, which is a useful monomer of a fluorine-containing polymer material, while producing no toxic perfluoroisobutene at all, eliminating the need for separation and detoxification equipment, and being economical. It is to provide a method that can be manufactured.
[0006]
[Means for Solving the Problems]
As a result of intensive studies on a method for producing hexafluoropropene in order to solve the above-mentioned problems, the present inventor can produce highly toxic perfluoroisobutene by producing hexafluoropropene in multiple stages by the production method described below. Since it was not generated at all, it was found that the device for separation and abatement was not necessary and it was economical, and the present invention was completed.
[0007]
That is, the present invention
General formula (1):
XCF₂CF₂CHClY
(However, in this general formula, X and Y are each a fluorine atom or a chlorine atom.)
The propane compound represented by
General formula (2):
XCF₂CF = CClY
(However, in this general formula, X and Y are the same as described above.)
A first step of obtaining a propene compound represented by:
A second step of fluorinating the propene compound with hydrofluoric anhydride in the presence of an antimony catalyst in the liquid phase to obtain 1,1,1,2,3,3-hexafluoro-3-chloropropane;
A third step of dehydrochlorinating 1,1,1,2,3,3-hexafluoro-3-chloropropane to obtain hexafluoropropene;
It relates to a multistage production method of hexafluoropropene having
[0008]
In the production method of the present invention, the first step, general formula (1): XCF₂CF₂A propane compound represented by CHClY (X and Y are each F or Cl) is dehydrofluorinated to give a general formula (2): XCF₂A process for obtaining a propene compound represented by CF = CClY (X and Y are the same as those in formula (1)) will be described.
[0009]
Raw material XCF₂CF₂Examples of propane compounds represented by CHClY (X and Y are F and Cl, respectively) include 1,1,1,2,2,3-hexafluoro-3-chloropropane (hereinafter referred to as HCFC-226ca), 1, 1,1,2,2-pentafluoro-3,3-dichloropropane (hereinafter referred to as HCFC-225ca), 1,1,2,2,3-pentafluoro-1,3-dichloropropane (hereinafter referred to as HCFC-225ca) HCFC-225cb), 1,1,2,2-tetrafluoro-1,3,3-trichloropropane (hereinafter referred to as HCFC-224ca) and the like.
[0010]
HCFC-226ca is obtained by fluorinating HCFC-225ca or 225cb with anhydrous hydrofluoric acid in the presence of a catalyst such as chromium. HCFC-225ca and HCFC-225cb are easily produced by reacting tetrafluoroethylene and fluorodichloromethane, and HCFC-224ca by reacting tetrafluoroethylene and chloroform in the presence of a Lewis acid catalyst such as aluminum chloride. Can be a raw material.
[0011]
(Dehydrofluoric acid in liquid phase)
The dehydrofluorination reaction from these compounds is KOH, NaOH, Ca (OH)₂It can be carried out with inorganic basic compounds such as alkali metal hydroxides and alkaline earth metal hydroxides, organic basic compounds such as amines, and alkali metal alkoxides. It is preferable to use a basic compound. As a solvent for the dehydrofluorination reaction, water, alcohols such as methanol, ethers such as dibutyl ether, and the like can be used, but water is preferably used as a solvent from the viewpoint of product recovery and economy. .
[0012]
When the hydrofluoric acid reaction is performed using calcium hydroxide, an aqueous solution or a slurry formed by mixing water and calcium hydroxide may be used. Moreover, you may mix and use potassium hydroxide at this time. An advantage of using calcium hydroxide is that calcium fluoride produced by dehydrofluoric acid can be reused as a raw material for hydrofluoric acid.
[0013]
When the dehydrofluorination reaction is carried out in an aqueous solution, a phase transfer catalyst such as a quaternary ammonium salt, a phosphonium salt, or a crown ether can be used in order to make the reaction proceed smoothly.
[0014]
Examples of the cation of the quaternary ammonium salt include benzyltriethylammonium, trioctylmethylammonium, tricaprylmethylammonium, tetrabutylammonium and the like. Examples of the cation of the quaternary phosphonium salt include tetrabutylphosphonium and trioctylethylphosphonium. Although the anion which forms a salt with those cations is not limited, In general, a chlorine ion, a bromine ion, a hydrogen sulfate ion, etc. are mentioned. Examples of the crown ether include 18-crown-6 and dibenzo-18-crown-6. However, the above is merely an example and does not limit the type of phase transfer catalyst.
[0015]
These aqueous solutions can be reused by separating the fluoride produced after the reaction by a precipitation method, a filtration method or the like and then adding an alkali again.
[0016]
Although reaction temperature is not specifically limited, It can implement in 30-150 degreeC. For example, in the case of HCFC-226ca, which is a compound having a low boiling point, it can be carried out in a pressurized reaction vessel.
[0017]
(Dehydrofluoric acid in gas phase)
The hydrofluoric acid reaction may be a gas phase reaction using a metal oxide as a catalyst. The metal oxide may be an aqueous solution of Fe, Cr, Cu chloride, sulfate, nitrate, an alkali ammonia solution or alkali. The metal hydroxide obtained by adding metal hydroxide or adding urea and heating can be obtained by firing. In the case of chromium, it can be prepared by reducing hexavalent chromium.
[0018]
These metal oxides can be used alone, but may be a composite oxide or a mixed oxide of a plurality of metals selected from these metals (Fe, Cr, Cu).
[0019]
In the case of chromium oxide, it is possible to use a partially fluorinated oxide, and the fluorination can usually be carried out by fluorination treatment at 20 to 450 ° C., preferably 200 to 400 ° C. However, anhydrous hydrofluoric acid may be used, or heat treatment with fluorinated hydrocarbon can be used. The partially fluorinated chromium oxide can also be obtained by oxygenating a chromium trifluoride hydrate.
[0020]
These metal oxides may be granulated or compressed into pellets. These may be supported on a carrier not directly involved in the reaction, such as aluminum fluoride or silica gel. In order to prevent deterioration of the catalyst, oxygen, air, etc. may be circulated simultaneously with the raw materials.
[0021]
The dehydrofluorination reaction can also be a gas phase reaction using activated carbon as a catalyst. Although it does not limit about the kind of activated carbon, granular activated carbon, coconut shell activated carbon, etc. are used suitably.
[0022]
The reaction temperature for the gas phase reaction is preferably 200 to 600 ° C, more preferably 250 to 500 ° C.
[0023]
As a gas phase reaction method, a method using a fixed bed type flow reaction apparatus, a fluidized bed type flow reaction apparatus, or the like can be employed.
[0024]
In the production method of the present invention, the second step, general formula (2): XCF₂A propene compound represented by CF = CClY (X and Y are the same as those in formula (1)) is fluorinated with anhydrous hydrofluoric acid using antimony as a catalyst in a liquid phase, and 1,1,1,2,3, A method for obtaining 3-hexafluoro-3-chloropropane (hereinafter referred to as HCFC-226ea) will be described.
[0025]
In the present invention, it is particularly important to carry out the reaction by a liquid phase method using an antimony catalyst. As the antimony catalyst, antimony fluorinated chloride obtained by fluorinating antimony pentachloride and antimony trichloride can be used as the catalyst. When chlorine is present on the catalyst, it is represented by the general formula (2). Since chlorination of the propene compound may proceed and the selectivity of the reaction may be reduced, it is preferable to use fully fluorinated antimony pentafluoride and antimony trifluoride as a catalyst.
[0026]
The pentavalent antimony halide (for example, antimony pentafluoride) and the trivalent antimony halide (for example, antimony trifluoride) can be used alone or in combination.
[0027]
In the present invention, a solvent is not particularly required, but anhydrous HF, which is a reactant, can be used as a solvent. A reaction solvent can be used as necessary, and any solvent can be used as long as it is inert to the catalyst. Examples thereof include perfluoro compounds such as perfluorohexane, perfluorodecalin, and perfluorotributylamine.
[0028]
When antimony pentafluoride is used as a catalyst and anhydrous HF is used as a reaction solvent, since the corrosiveness is strong, the concentration of the antimony catalyst may be limited depending on the material of the reaction vessel. In the case of a reaction vessel made of a fluororesin, the concentration of the catalyst is not limited, but in the case of a reaction vessel such as Hastelloy C22 which is a corrosion resistant material, the catalyst concentration is limited. When only antimony pentafluoride is used as a catalyst, 1 mol% or less, more preferably 0.5 mol% or less with respect to anhydrous HF is preferable in terms of corrosion.
[0029]
When antimony pentafluoride and antimony trifluoride are mixed and used, the mixing molar ratio is antimony pentafluoride / antimony trifluoride ≦ 2, more preferably antimony pentafluoride / antimony trifluoride ≦ 1, The concentration of the mixed antimony pentafluoride is preferably 10 mol% or less, more preferably 3 mol% or less with respect to anhydrous HF, in view of corrosion.
[0030]
When only antimony trifluoride is used as a catalyst and anhydrous HF is used as a reaction solvent, the concentration of the catalyst is not limited because the corrosivity is very small.
[0031]
In order to avoid the corrosive problem, the propene compound represented by the general formula (2) and anhydrous HF are charged into antimony pentafluoride, and the produced HCFC-226ea and unreacted anhydrous HF or / and the general formula A reaction form in which the propene compound represented by (2) is extracted out of the reaction system and anhydrous HF does not accumulate in the reaction system can be employed in the present invention.
[0032]
The reaction temperature is not particularly limited, but is 25 to 150 ° C, more preferably 40 to 100 ° C.
[0033]
The reaction pressure is not particularly limited, but from atmospheric pressure to 50 kg / cm.²G, more preferably from atmospheric pressure to 30 kg / cm²G can be adopted.
[0034]
Although the molar ratio of the propene compound represented by the general formula (2) and anhydrous HF can be arbitrarily changed, in order to increase the selectivity of the reaction, HF / propene compound = 4 or more is preferable. In this case, unreacted HF may come out of the reaction system together with HCFC-226ea, but even at this time, HF can be recycled to the reaction system after separation.
[0035]
As a form of reaction, a batch method in which a reaction is performed after supplying necessary raw materials and a product is recovered, a semi-batch method in which one raw material is continuously charged and a product is continuously extracted, or A method of continuously charging raw materials and continuously extracting products and the like can be employed.
[0036]
In the production method of the present invention, a method for obtaining hexafluoropropene by dehydrochlorinating 1,1,1,2,3,3-hexafluoro-3-chloropropane (HCFC-226ea), which is the third stage, will be described. .
[0037]
(Dehydrochlorination in liquid phase)
The dehydrochlorination reaction from HCFC-226ea is KOH, NaOH, Ca (OH)₂It can be carried out with inorganic basic compounds such as alkali metal hydroxides, alkaline earth metal hydroxides, etc., organic basic compounds such as amines, alkali metal alkoxides, etc. It is preferable to use the basic compound. As the solvent for the dehydrochlorination reaction, water, alcohols such as methanol, ethers such as dibutyl ether, and the like can be used. From the viewpoint of product recovery and economy, water is preferably used as the solvent.
[0038]
When the dehydrochlorination reaction is performed using calcium hydroxide, an aqueous solution or a slurry formed by mixing water and calcium hydroxide may be used. At this time, a mixture with potassium hydroxide or sodium hydroxide may be used.
[0039]
When the dehydrochlorination reaction is carried out in an aqueous solution, a phase transfer catalyst such as a quaternary ammonium salt, a phosphonium salt, or a crown ether can be used in order to make the reaction proceed smoothly.
[0040]
Examples of the cation of the quaternary ammonium salt include benzyltriethylammonium, trioctylmethylammonium, tricaprylmethylammonium, tetrabutylammonium and the like. Examples of the cation of the quaternary phosphonium salt include tetrabutylphosphonium and trioctylethylphosphonium. The anions that form salts with these cations are not limited, but generally include chloride ions, bromine ions, hydrogen sulfate ions, and the like. Examples of the crown ether include 18-crown-6, dibenzo-18-crown-6 and the like. However, the above is merely an example and does not limit the type of phase transfer catalyst.
[0041]
These aqueous solutions can be reused by separating the chloride produced after the reaction by precipitation, filtration, etc., and then adding alkali again.
[0042]
Although reaction temperature is not specifically limited, It can implement in the range of 30-150 degreeC, and can also be implemented in a pressurized reaction container.
[0043]
(Dehydrochlorination in gas phase)
The dehydrochlorination reaction can also be a gas phase reaction using a metal oxide as a catalyst. As the metal oxide, an aqueous solution of Fe, Co, Ni, Cr, Cu chloride, sulfate, nitrate, or an alkaline ammonia solution Alternatively, it can be obtained by adding an alkali metal hydroxide or adding urea and calcining a metal hydroxide obtained by heating. In the case of chromium, it can be prepared by reducing hexavalent chromium.
[0044]
These metal oxides can be used alone, but may be a composite oxide or a mixed oxide of a plurality of metals selected from these metals (Fe, Co, Ni, Cr, Cu).
[0045]
In the case of chromium oxide, it is also possible to use a partially fluorinated oxide, and the fluorination can usually be carried out by fluorination treatment at 20 to 450 ° C., preferably 200 to 400 ° C. However, anhydrous hydrofluoric acid may be used, or heat treatment with fluorinated hydrocarbon can be used. The partially fluorinated chromium oxide can also be obtained by oxygenating a chromium trifluoride hydrate.
[0046]
These metal oxides may be granulated or compressed into pellets. These may be supported on a carrier not directly involved in the reaction, such as aluminum fluoride or silica gel. In order to prevent deterioration of the catalyst, oxygen, air, etc. may be circulated simultaneously with the raw materials.
[0047]
The dehydrochlorination reaction can be performed by a gas phase reaction using activated carbon as a catalyst. Although it does not limit about the kind of activated carbon, granular activated carbon, coconut shell activated carbon, etc. are used suitably.
[0048]
The reaction temperature of the gas phase reaction is preferably 200 to 600 ° C, more preferably 250 to 500 ° C.
[0049]
As a gas phase reaction method, a method using a fixed bed type flow reaction apparatus, a fluidized bed type flow reaction apparatus, or the like can be employed.
[0050]
[Effects of the invention]
According to the present invention, by a multi-step process of dehydrofluoric acid of the propane compound of the general formula (1), fluorination of the propene compound of the general formula (2) by this dehydrofluorination, Since no highly toxic perfluoroisobutene is produced, it is possible to produce hexafluoropropene, which is a useful monomer of a fluorine-containing polymer material, while having the economy of eliminating the need for separation and detoxification equipment.
[0051]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples.
[0052]
(Dehydrofluoric acid)
Example 1
In a 200 ml glass reaction vessel equipped with a dropping funnel and condenser, 40.7 g of 1,1,1,2,2-pentafluoro-3,3-dichloropropane (HCFC-225ca) and 0.5 g of tetrabutylammonium bromide were added. Charged and stirred at room temperature.
[0053]
From an addition funnel, an aqueous solution in which 16.8 g of potassium hydroxide was dissolved in 50 ml of water was added dropwise so that the reaction temperature was maintained at 30 ° C.
[0054]
After completion of the dropwise addition, the reaction was continued for further 2 hours, and then the organic layer was separated and analyzed by gas chromatography. The conversion of HCFC-225ca was 100%, and 1,1,1,2-tetrafluoro- 3,3-Dichloropropene was produced with a selectivity of 98%. When the organic layer was dried with calcium chloride and distilled, 1,1,1,2-tetrafluoro-3,3-dichloropropene had a boiling point of 46 ° C.
[0055]
Example 2
In a 200 ml glass reaction vessel equipped with a condenser, 40.7 g of 1,1,2,2,3-pentafluoro-1,3-dichloropropane (HCFC-225cb), 0.5 g of methyltrioctylammonium chloride, 16.8 potassium hydroxide An aqueous solution in which g was dissolved in 50 ml of water was charged.
[0056]
The reaction was carried out at 55 ° C. with stirring, and after the reaction for 10 hours, analysis was carried out in the same manner as above. As a result, the conversion of HCFC-225cb was 15%, Dichloropropene was produced with a selectivity of 98%.
[0057]
Example 3
An aqueous solution and tetrabutylammonium bromide in which 16.8 g of potassium hydroxide is dissolved in 50 ml of water in a 200 ml glass reaction vessel equipped with a dropping funnel and a condenser
 0.5 g was charged and stirred at 40 ° C.
[0058]
From the dropping funnel, 43.9 g of 1,1,2,2-tetrafluoro-1,3,3-trichloropropane (HCFC-224ca) was added dropwise so that the reaction temperature was kept at 40 ° C.
[0059]
After completion of the dropwise addition, the reaction was continued for further 4 hours, and then the organic layer was separated and analyzed by gas chromatography. The conversion of HCFC-224ca was 99% and the desired 1,1,2-trifluoro- The selectivity for 1,3,3-trichloropropene was 96%.
[0060]
Example 4
An SUS316 autoclave was charged with an aqueous solution prepared by dissolving 16.8 g of potassium hydroxide in 50 ml of water and 0.5 g of tetrabutylammonium bromide, and cooled to −20 ° C.
[0061]
After cooling, 37.3 g of 1,1,1,2,2,3-hexafluoro-3-chloropropane (HCFC-226ca) was charged into an autoclave and returned to room temperature. Stirring was started, and the temperature inside the reactor was kept at 80 ° C. for 8 hours. After completion of the reaction, the product was recovered in a trap cooled to -70 ° C under atmospheric pressure first and then under reduced pressure.
[0062]
The recovered organic matter was analyzed by gas chromatography. As a result, the conversion of HCFC-226ca was 20%, and the selectivity for the desired 1,1,1,2-tetrafluoro-3-chloropropene-2 was 96%. there were.
[0063]
Example 5
Chromium hydroxide prepared from an aqueous chromium nitrate solution and aqueous ammonia was filtered off, washed with water, dried at 100 ° C., and molded into a cylindrical shape having a diameter of 3 mm and a height of 3 mm using a tableting molding machine.
[0064]
The catalyst thus obtained was charged into a Hastelloy C reaction tube before the reaction, and heated and held at 400 ° C. for 1 hour in a nitrogen stream. Thereafter, the temperature was lowered to 200 ° C., hydrofluoric acid was supplied, and the mixture was treated for 1 hour to be activated.
[0065]
A catalyst (20 g) prepared as described above was filled in a Hastelloy C reaction tube having an inner diameter of 2 cm and a length of 40 cm, and heated to 350 ° C. in an electric furnace while flowing nitrogen gas. Nitrogen was changed to HCFC-225ca (57 cc / min) and accompanied by oxygen (3 cc / min) and circulated through the reaction tube.
[0066]
The reaction tube outlet gas was washed with water, dried over calcium chloride, and analyzed by gas chromatography. One hour after the start of the reaction, the conversion of HCFC-225ca was 70%, and the selectivity for the desired 1,1,1,2-tetrafluoro-3,3-dichloropropene-2 was 85%.
[0067]
Example 6
The reaction was performed in the same manner as in Example 5 except that the copper oxide-chromia composite oxide was used as the catalyst. One hour after the start of the reaction, the conversion of HCFC-225ca was 52%, and the selectivity for the desired 1,1,1,2-tetrafluoro-3,3-dichloropropene-2 was 83%.
[0068]
Example 7
The reaction was carried out in the same manner as in Example 1 except that iron oxide was used as the catalyst. One hour after the start of the reaction, the conversion of HCFC-225ca was 33%, and the selectivity for the desired 1,1,1,2-tetrafluoro-3,3-dichloropropene-2 was 86%.
[0069]
(Fluorination)
Example 8
SbF in Hastelloy C22 autoclave with internal volume of 200ml_Five 2.0g was charged. After cooling the autoclave to −30 ° C., 50 g of anhydrous HF and 20 g of 1,1,1,2-tetrafluoro-3,3-dichloropropene obtained in Example 1 above were charged, and then returned to room temperature with stirring. The reaction was continued at 80 ° C. for 10 hours. While removing HCl generated at this time, the reaction pressure was 12 kg / cm.²Kept.
[0070]
The reaction product was collected from the autoclave in a trap cooled to −70 ° C. while removing HF with a washing tower and an alkaline water tower. The collected organic matter was analyzed by gas chromatography.
[0071]
As a result of the analysis, the conversion of 1,1,1,2-tetrafluoro-3,3-dichloropropene was 99%, 1,1,1,2,3,3-hexafluoro-3-chloropropane (HCFC-226ea). ) Was 99.9% or more.
[0072]
Example 9
In Example 8, the catalyst was SbF_FiveInstead of SbF_Five 5.4g and SbF_Three 8.9 g was charged and reacted in the same manner.
[0073]
As a result of the same analysis, the conversion of 1,1,1,2-tetrafluoro-3,3-dichloropropene was 99%, 1,1,1,2,3,3-hexafluoro-3-chloropropane (HCFC The selectivity of -226ea) was almost 99% or more.
[0074]
Example Ten
SbCl in SUS316 autoclave with PTFE inner tube with internal volume of 500ml_Five60g was charged. After cooling the autoclave to −30 ° C., 250 g of anhydrous HF was charged, the temperature was returned to room temperature, and then heated to 80 ° C. with stirring. At this time, while removing the generated HCl out of the system, the reaction pressure was 12 kg / cm2.²Kept.
[0075]
After the generation of hydrochloric acid ceased, 1,1,1,2-tetrafluoro-3,3-dichloropropene obtained in Example 1 was charged at 100 g / Hr at 80 ° C. At this time, while removing the generated HCl out of the system, the reaction pressure was 12 kg / cm2.²Kept. After 3 hours, charging of 1,1,1,2-tetrafluoro-3,3-dichloropropene was stopped, and the reaction was further continued at 80 ° C. for 3 hours.
[0076]
The reaction product was collected in a trap cooled to −70 ° C. while removing HF with a washing tower and an alkaline water tower. The collected organic matter was analyzed by gas chromatography.
[0077]
As a result of the analysis, the conversion of 1,1,1,2-tetrafluoro-3,3-dichloropropene was 99%, and 1,1,1,2,3,3-hexafluoro-3-chloropropane (HCFC) The selectivity for -226ea) was 95%. The main by-product was 1,1,1,2,3-trifluoro-3,3-dichloropropane.
[0078]
In a reaction vessel in which the catalyst remained, 200 g of anhydrous HF was charged, and similarly, 300 g of 1,1,1,2-tetrafluoro-3,3-dichloropropene was charged and reacted. As a result of analyzing the product by gas chromatography, the conversion of 1,1,1,2-tetrafluoro-3,3-dichloropropene was 99%, and 1,1,1,2,3,3-hexa The selectivity for fluoro-3-chloropropane (HCFC-226ea) was 96%.
[0079]
Example 11
In Example 8, the raw material was changed to 1,1,2-trifluoro-1,3,3-trichloropropene obtained in Example 3 above, and the same reaction was carried out. As a result, 1,1,2-trifluoro-1 The conversion of 1,3,3-trichloropropene was 99%, and the selectivity for 1,1,1,2,3,3-hexafluoro-3-chloropropane (HCFC-226ea) was 98%.
[0080]
Example 12
In Example 8, the raw material was changed to 1,1,2,3-tetrafluoro-1,3-dichloropropene obtained in Example 2 above, and the same reaction was performed. As a result, 1,1,2,3-tetrafluoro was obtained. The conversion of -1,3-dichloropropene was 99%, and the selectivity of 1,1,1,2,3,3-hexafluoro-3-chloropropane (HCFC-226ea) was 97%.
[0081]
(Dehydrochloric acid)
Example 13
A 200 ml glass reaction vessel equipped with a gas inlet tube, a condenser cooled to -5 ° C., and a trap at −70 ° C. for collecting the gas that escapes from the top of the condenser, 16.8 g of potassium hydroxide in 50 ml of water Aqueous solution and 0.5 g of tetrabutylammonium bromide were charged and stirred at 0 ° C.
[0082]
37.3 g of 1,1,1,2,3,3-hexafluoro-3-chloropropane (HCFC-226ea) (boiling point: 18-19 ° C.) obtained in Example 8 above from the gas inlet tube, the reaction temperature was 0 ° C. It was charged in a gas state so as to keep it. At this time, the amount of hexafluoropropene generated was released from the reaction system, and the amount charged was adjusted so that HCFC-226ea trying to escape from the reaction system together with hexafluoropropene was refluxed by a condenser.
[0083]
After completion of the charging, the reaction was further continued at 10 ° C. for 2 hours, and then the reaction was completed. At this time, there was no organic matter in the reactor. When the organic layer in the trap was analyzed by gas chromatography, the conversion of HCFC-226ea was 98%, and the desired hexafluoropropene was produced at a selectivity of 99%.
[0084]
Example 14
A Hastelloy C reaction tube with an inner diameter of 2 cm and a length of 40 cm was filled with 10 g of coconut shell activated carbon (Yacoal M, manufactured by Taihei Chemical Co., Ltd.) and heated at 400 ° C. for 2 hours in an electric furnace while nitrogen gas was circulated. .
[0085]
Nitrogen was changed to HCFC-226ea (100 cc / min) obtained in Example 8 above, and then circulated through the reaction tube. The reaction tube outlet gas was washed with water, dried with calcium chloride, and then analyzed by gas chromatography. One hour after the start of the reaction, the conversion of HCFC-226ea was 15%, and the selectivity for the desired hexafluoropropene was 98%. Unreacted HCFC-226ea could be reused after recovery.

Claims (18)

General formula (1):
XCF ₂ CF ₂ CHClY
(However, in this general formula, X and Y are each a fluorine atom or a chlorine atom.)
The propane compound represented by
General formula (2):
XCF ₂ CF = CClY
(However, in this general formula, X and Y are the same as described above.)
A first step of obtaining a propene compound represented by:
A second step of fluorinating the propene compound with hydrofluoric anhydride in the presence of an antimony catalyst in the liquid phase to obtain 1,1,1,2,3,3-hexafluoro-3-chloropropane;
A process for producing hexafluoropropene, comprising a third step of dehydrochlorinating 1,1,1,2,3,3-hexafluoro-3-chloropropane to obtain hexafluoropropene. The production method according to claim 1, wherein the dehydrofluorination in the first step is performed with an alkaline aqueous solution. The production method according to claim 2, wherein the dehydrofluorination is performed with an alkaline aqueous solution in the presence of a phase transfer catalyst. The production method according to claim 2 or 3, wherein the aqueous alkaline solution is an aqueous solution of KOH, NaOH, or Ca (OH) ₂ . The production method according to claim 4, wherein the dehydrofluorination is performed with a slurry formed of calcium hydroxide and water. The production method according to claim 1, wherein the dehydrofluorination in the first step is performed by a gas phase reaction using at least one of chromium, iron and copper as a catalyst. The production method according to claim 1, wherein the hydrofluoric acid in the first step is performed by a gas phase reaction using an activated carbon catalyst. The production method according to claim 1, wherein the antimony catalyst of the fluorination reaction in the second step is pentavalent antimony halide, trivalent antimony halide, or a mixture thereof. The production method according to claim 8, wherein the antimony catalyst is a mixture of antimony pentafluoride and antimony trifluoride. The production method according to claim 8, wherein the antimony catalyst is antimony pentafluoride. The production method according to claim 1, wherein the fluorination reaction in the second step is performed using anhydrous hydrofluoric acid as a solvent. The production method according to claim 1, wherein the dehydrochlorination in the third step is performed with an alkaline aqueous solution. 13. The production method according to claim 12, wherein dehydrochlorination is performed with an alkaline aqueous solution in the presence of a phase transfer catalyst. 14. The production method according to claim 12 or 13, wherein the alkaline aqueous solution is an aqueous solution of KOH, NaOH or Ca (OH) ₂ . 15. The production method according to claim 14, wherein the dehydrochlorination is performed with a slurry formed of calcium hydroxide and water. The production method according to claim 1, wherein dehydrochlorination in the third step is performed in a gas phase using at least one of chromium, nickel, iron, cobalt and copper as a catalyst. The production method according to claim 1, wherein the dehydrochlorination in the third step is performed in a gas phase using activated carbon as a catalyst. The compound represented by the general formula (1) is 1,1,1,2,2,3-hexafluoro-3-chloropropane, 1,1,1,2,2-pentafluoro-3,3-dichloropropane. The production according to claim 1, which is 1,1,2,2,3-pentafluoro-1,3-dichloropropane or 1,1,2,2-tetrafluoro-1,3,3-trichloropropane. Method.