CN117623857A - Purification method of electronic grade octafluoro-2-butene - Google Patents
Purification method of electronic grade octafluoro-2-butene Download PDFInfo
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- CN117623857A CN117623857A CN202210964045.5A CN202210964045A CN117623857A CN 117623857 A CN117623857 A CN 117623857A CN 202210964045 A CN202210964045 A CN 202210964045A CN 117623857 A CN117623857 A CN 117623857A
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- WSJULBMCKQTTIG-OWOJBTEDSA-N (e)-1,1,1,2,3,4,4,4-octafluorobut-2-ene Chemical compound FC(F)(F)C(/F)=C(\F)C(F)(F)F WSJULBMCKQTTIG-OWOJBTEDSA-N 0.000 title claims abstract description 94
- 238000000034 method Methods 0.000 title claims abstract description 30
- 238000000746 purification Methods 0.000 title claims abstract description 24
- 239000012535 impurity Substances 0.000 claims abstract description 56
- NUPBXTZOBYEVIR-UHFFFAOYSA-N 1,1,2,3,3,4,4-heptafluorobut-1-ene Chemical compound FC(F)C(F)(F)C(F)=C(F)F NUPBXTZOBYEVIR-UHFFFAOYSA-N 0.000 claims abstract description 43
- 238000000605 extraction Methods 0.000 claims abstract description 40
- -1 ester compounds Chemical class 0.000 claims abstract description 17
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 11
- WZCQDYGWGDYQNC-OWOJBTEDSA-N (e)-2-chloro-1,1,1,3,4,4,4-heptafluorobut-2-ene Chemical compound FC(F)(F)C(/F)=C(\Cl)C(F)(F)F WZCQDYGWGDYQNC-OWOJBTEDSA-N 0.000 claims abstract description 10
- 150000001335 aliphatic alkanes Chemical class 0.000 claims abstract description 8
- 150000001298 alcohols Chemical class 0.000 claims abstract description 5
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 claims description 66
- 239000000047 product Substances 0.000 claims description 36
- VZGDMQKNWNREIO-UHFFFAOYSA-N tetrachloromethane Chemical compound ClC(Cl)(Cl)Cl VZGDMQKNWNREIO-UHFFFAOYSA-N 0.000 claims description 20
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 17
- 239000012043 crude product Substances 0.000 claims description 17
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 12
- 239000013067 intermediate product Substances 0.000 claims description 12
- ZHNUHDYFZUAESO-UHFFFAOYSA-N Formamide Chemical compound NC=O ZHNUHDYFZUAESO-UHFFFAOYSA-N 0.000 claims description 10
- BLNWTWDBKNPDDJ-UHFFFAOYSA-N 1,1,1,2,3,4,4-heptafluorobut-2-ene Chemical compound FC(F)C(F)=C(F)C(F)(F)F BLNWTWDBKNPDDJ-UHFFFAOYSA-N 0.000 claims description 8
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 claims description 8
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 8
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 claims description 6
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 claims description 6
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 claims description 5
- FYDLLXJLGCDGFH-UHFFFAOYSA-N 1,3,3,3-tetrafluoro-2-(trifluoromethyl)prop-1-ene Chemical group FC=C(C(F)(F)F)C(F)(F)F FYDLLXJLGCDGFH-UHFFFAOYSA-N 0.000 claims description 4
- DLFVBJFMPXGRIB-UHFFFAOYSA-N Acetamide Chemical compound CC(N)=O DLFVBJFMPXGRIB-UHFFFAOYSA-N 0.000 claims description 4
- KXDAEFPNCMNJSK-UHFFFAOYSA-N Benzamide Chemical compound NC(=O)C1=CC=CC=C1 KXDAEFPNCMNJSK-UHFFFAOYSA-N 0.000 claims description 4
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 claims description 4
- 235000019441 ethanol Nutrition 0.000 claims description 4
- TZIHFWKZFHZASV-UHFFFAOYSA-N methyl formate Chemical compound COC=O TZIHFWKZFHZASV-UHFFFAOYSA-N 0.000 claims description 4
- KZNICNPSHKQLFF-UHFFFAOYSA-N succinimide Chemical compound O=C1CCC(=O)N1 KZNICNPSHKQLFF-UHFFFAOYSA-N 0.000 claims description 4
- 238000011084 recovery Methods 0.000 claims description 3
- 150000001408 amides Chemical class 0.000 claims description 2
- KVNRLNFWIYMESJ-UHFFFAOYSA-N butyronitrile Chemical compound CCCC#N KVNRLNFWIYMESJ-UHFFFAOYSA-N 0.000 claims description 2
- 150000002148 esters Chemical class 0.000 claims description 2
- ALBYIUDWACNRRB-UHFFFAOYSA-N hexanamide Chemical compound CCCCCC(N)=O ALBYIUDWACNRRB-UHFFFAOYSA-N 0.000 claims description 2
- 150000002825 nitriles Chemical class 0.000 claims description 2
- PNJWIWWMYCMZRO-UHFFFAOYSA-N pent‐4‐en‐2‐one Natural products CC(=O)CC=C PNJWIWWMYCMZRO-UHFFFAOYSA-N 0.000 claims description 2
- QLNJFJADRCOGBJ-UHFFFAOYSA-N propionamide Chemical compound CCC(N)=O QLNJFJADRCOGBJ-UHFFFAOYSA-N 0.000 claims description 2
- 229940080818 propionamide Drugs 0.000 claims description 2
- FVSKHRXBFJPNKK-UHFFFAOYSA-N propionitrile Chemical compound CCC#N FVSKHRXBFJPNKK-UHFFFAOYSA-N 0.000 claims description 2
- 229960002317 succinimide Drugs 0.000 claims description 2
- 238000000895 extractive distillation Methods 0.000 description 23
- 239000007789 gas Substances 0.000 description 13
- 239000000203 mixture Substances 0.000 description 7
- 238000000926 separation method Methods 0.000 description 7
- 238000001179 sorption measurement Methods 0.000 description 6
- 239000012071 phase Substances 0.000 description 5
- 238000005292 vacuum distillation Methods 0.000 description 5
- 238000002360 preparation method Methods 0.000 description 4
- ZVJOQYFQSQJDDX-UHFFFAOYSA-N 1,1,2,3,3,4,4,4-octafluorobut-1-ene Chemical compound FC(F)=C(F)C(F)(F)C(F)(F)F ZVJOQYFQSQJDDX-UHFFFAOYSA-N 0.000 description 3
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 229910052731 fluorine Inorganic materials 0.000 description 3
- 239000011737 fluorine Substances 0.000 description 3
- 239000007791 liquid phase Substances 0.000 description 3
- 238000004064 recycling Methods 0.000 description 3
- 238000004088 simulation Methods 0.000 description 3
- 238000004364 calculation method Methods 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- NLOLSXYRJFEOTA-UHFFFAOYSA-N 1,1,1,4,4,4-hexafluorobut-2-ene Chemical compound FC(F)(F)C=CC(F)(F)F NLOLSXYRJFEOTA-UHFFFAOYSA-N 0.000 description 1
- GHQCCHWTDLTMJT-UHFFFAOYSA-N 3-(3-methoxybenzyl)-1h-pyrrolo[2,3-b]pyridine Chemical compound COC1=CC=CC(CC=2C3=CC=CN=C3NC=2)=C1 GHQCCHWTDLTMJT-UHFFFAOYSA-N 0.000 description 1
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 description 1
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 238000004587 chromatography analysis Methods 0.000 description 1
- DEZRYPDIMOWBDS-UHFFFAOYSA-N dcm dichloromethane Chemical compound ClCCl.ClCCl DEZRYPDIMOWBDS-UHFFFAOYSA-N 0.000 description 1
- 238000006704 dehydrohalogenation reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 239000012847 fine chemical Substances 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000004334 fluoridation Methods 0.000 description 1
- NBVXSUQYWXRMNV-UHFFFAOYSA-N fluoromethane Chemical compound FC NBVXSUQYWXRMNV-UHFFFAOYSA-N 0.000 description 1
- 229920002313 fluoropolymer Polymers 0.000 description 1
- 239000004811 fluoropolymer Substances 0.000 description 1
- 239000004088 foaming agent Substances 0.000 description 1
- 238000004508 fractional distillation Methods 0.000 description 1
- 239000008246 gaseous mixture Substances 0.000 description 1
- WMIYKQLTONQJES-UHFFFAOYSA-N hexafluoroethane Chemical compound FC(F)(F)C(F)(F)F WMIYKQLTONQJES-UHFFFAOYSA-N 0.000 description 1
- HCDGVLDPFQMKDK-UHFFFAOYSA-N hexafluoropropylene Chemical group FC(F)=C(F)C(F)(F)F HCDGVLDPFQMKDK-UHFFFAOYSA-N 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002808 molecular sieve Substances 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- QYSGYZVSCZSLHT-UHFFFAOYSA-N octafluoropropane Chemical compound FC(F)(F)C(F)(F)C(F)(F)F QYSGYZVSCZSLHT-UHFFFAOYSA-N 0.000 description 1
- 229960004065 perflutren Drugs 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000003507 refrigerant Substances 0.000 description 1
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- BFKJFAAPBSQJPD-UHFFFAOYSA-N tetrafluoroethene Chemical group FC(F)=C(F)F BFKJFAAPBSQJPD-UHFFFAOYSA-N 0.000 description 1
- TXEYQDLBPFQVAA-UHFFFAOYSA-N tetrafluoromethane Chemical compound FC(F)(F)F TXEYQDLBPFQVAA-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention discloses a purification method and a device of electronic grade octafluoro-2-butene, wherein the purification method comprises the following steps: and (3) an extraction and rectification step: extracting and rectifying the crude octafluoro-2-butene product in the presence of an extracting agent, wherein the extracting agent is at least one selected from ester compounds, halogenated alkanes, amide compounds, nitrile compounds and alcohol compounds; a cryogenic rectification step; the crude octafluoro-2-butene product comprises at least one of 3-chloroheptafluoro-2-butene, 2, 3-dichloro-1, 4-hexafluoro-2-butene, octafluoro-2-butene dimer and heptafluorobutene impurities; after the extraction and rectification step, the removal rate of the heptafluorobutene impurities is more than or equal to 99 percent; after the extraction rectification step and the low-temperature rectification step, the electronic grade octafluoro-2-butene product with the purity more than or equal to 99.99 percent is obtained. The invention has the advantages of high product purity, low equipment cost, suitability for industrialized application and the like.
Description
Technical Field
The invention relates to the field of fluoridation, in particular to a method and a device for obtaining an electronic grade octafluoro-2-butene product by adopting the combination of extractive distillation and low-temperature distillation.
Background
Octafluoro-2-butene, abbreviated as 'C4F 8', is an important fluorine-containing fine chemical, has Ozone Depletion Potential (ODP) of 0 and low GWP, can be used as a polymerization monomer, and can also be applied to fields of refrigerants, foaming agents, thermodynamic cycle fluids, semiconductor etching gases, electric insulation gases, fire extinguishing agents and the like.
For the preparation method of octafluoro-2-butene, the prior art mainly adopts halogenated alkane dehydrohalogenation to obtain the preparation method of octafluoro-2-butene. The crude octafluoro-2-butene product obtained by the preparation method has the purity of 60% -90%, and contains 3-chloro heptafluoro-2-butene, 2, 3-dichloro-1, 4-hexafluoro-2-butene, octafluoro-2-butene dimer, and impurities such as heptafluoro-1-butene, heptafluoro-2-butene, heptafluoro-isobutylene and the like.
However, when octafluoro-2-butene is used as a semiconductor etching gas, the impurity content is very strict, and the impurity content must be strictly controlled at ppm or even ppb level. Therefore, the purification technology of octafluoro-2-butene is of remarkable significance for the application thereof in the field of electronic industry.
At present, few purification techniques for octafluoro-2-butene are reported.
Chinese patent CN213913041U discloses a fluorine-containing C4F8 electronic gas purifying apparatus, which comprises removing impurities by adsorption of a molecular sieve device, removing impurities by multiple adsorption of a first adsorption device, a second adsorption device and an nth adsorption device, and removing impurities by rectification, cold doubt and reboiling of a rectification device to obtain a high-purity fluorine-containing C4F8 electronic gas. However, the method has high equipment investment cost, and adopts a multi-stage adsorption process, so that the product loss is high and the yield is low.
Chinese patent CN102123780B discloses a method for recovering gaseous components comprising at least one fluorocarbon from a mixture of gaseous fluorocarbons by contacting a gaseous mixture of octafluorobutene or the like with a gas permeable separation medium comprising a non-porous fluoropolymer, thereby separating the two sets of gaseous components from each other, said separation medium comprising a diffusion membrane. The method can only realize the mutual separation of carbon tetrafluoride, tetrafluoroethylene, hexafluoroethane, hexafluoropropylene, octafluoropropane and octafluorobutene or C4F 8-isomer, and can not purify octafluorobutene products.
The octafluoro-2-butene and heptafluorobutene impurities are similar in structure and similar in boiling point, and are difficult to separate by common rectification to obtain the electronic-grade octafluoro-2-butene. There is no report on the prior art. Therefore, the method for purifying the octafluoro-2-butene, which has higher product purity, higher purification efficiency and lower production cost, is very practical.
Disclosure of Invention
In order to solve the technical problems, the invention provides a method for purifying electronic-grade octafluoro-2-butene, which has high product purity, high purification efficiency and low equipment cost and is suitable for industrial application.
The invention aims at realizing the following technical scheme:
an extractive distillation method of octafluoro-2-butene, the extractive distillation method comprising:
and (3) an extraction and rectification step: extracting and rectifying the crude octafluoro-2-butene product in the presence of an extracting agent, wherein the extracting agent is at least one selected from ester compounds, halogenated alkanes, amide compounds, nitrile compounds and alcohol compounds;
a cryogenic rectification step;
the crude octafluoro-2-butene product comprises at least one of 3-chloroheptafluoro-2-butene, 2, 3-dichloro-1, 4-hexafluoro-2-butene, octafluoro-2-butene dimer and heptafluorobutene impurities;
after the extraction and rectification step, the removal rate of the heptafluorobutene impurities is more than or equal to 99 percent; after the extraction rectification step and the low-temperature rectification step, the electronic grade octafluoro-2-butene product with the purity more than or equal to 99.99 percent is obtained.
The removal rate of the invention represents the content change of the heptafluorobutene impurities in the composition before and after extraction, rectification and purification, and the removal rate eta is calculated by the following modes:
wherein c 1 The unit of the content of the impurities of the heptafluorobutenes before extractive distillation is ppm; c 2 The content of the heptafluorobutene impurities after extractive distillation is in ppm.
The crude octafluoro-2-butene product is prepared by adopting a catalytic reaction process, wherein the crude product contains at least one of 3-chloro heptafluoro-2-butene, 2, 3-dichloro-1, 4-hexafluoro-2-butene, octafluoro-2-butene dimer and heptafluorobutene impurities; the heptafluorobutene impurities comprise at least one of heptafluoro-1-butene, heptafluoro-2-butene and heptafluoroisobutylene.
The extractive distillation step can effectively remove the heptafluorobutene impurities in the octafluoro-2-butene crude product. The content of the heptafluorobutene impurities can be different in the extraction and rectification effects. Preferably, the content of heptafluorobutene impurities in the octafluoro-2-butene crude product is less than 60%; more preferably, the content of heptafluorobutene-based impurities is < 2%; most preferably, the content of the heptafluorobutene-based impurity is < 1%.
The invention relates to a method for purifying electronic grade octafluoro-2-butene, which comprises the following steps:
the ester compound is at least one selected from methyl formate, ethyl acetate and 3- (dimethylamino) ethyl acrylate;
the halogenated alkane is selected from at least one of dichloromethane, chloroform and carbon tetrachloride;
the amide compound is at least one selected from formamide, acetamide, propionamide, caproamide, N-dimethylformamide, N-dimethylacetamide, benzamide and succinimide;
the nitrile compound is at least one selected from acetonitrile, propionitrile and butyronitrile;
the alcohol compound is at least one selected from absolute ethyl alcohol, absolute methyl alcohol and isopropyl alcohol.
The extractant is at least one selected from a single compound, a mixture of two or more extractants, a mixture of extractants and other solvents.
Preferably, the extractant is a single compound selected from formamide, N-dimethylformamide, N-dimethylacetamide, acetonitrile or absolute ethanol.
As another preferable scheme, the extractant is an extractant mixture, and the mass ratio of the extractant is 1% -99%. Preferably, the mixed extractant is at least one selected from the group consisting of a mixed extractant of acetonitrile and absolute ethanol, a mixed extractant of absolute ethanol and carbon tetrachloride, and a mixed extractant of acetonitrile and carbon tetrachloride.
The ratio of the extractant to the crude octafluoro-2-butene product of the present invention is not particularly limited. Considering the factors of product yield, raw material cost and the like, the mass ratio of the extractant to the composition containing octafluoro-2-butene and heptafluorobutene impurities is preferably 0.5-100: 1, more preferably 0.5 to 38:1.
compared with the extractant mentioned in the prior art, the extractive distillation tower with the same tower plate number is adopted to remove the heptafluorobutene impurities more efficiently. Alternatively, the same removal rate of heptafluorobutene impurities is obtained, and the number of tower plates of the extractive distillation tower is smaller.
Preferably, the invention adopts an extraction rectifying tower with the theoretical plate number of 10-80 to carry out extraction rectifying on the crude product containing octafluoro-2-butene, so as to remove heptafluoro-butene impurities which are difficult to remove in the crude product of octafluoro-2-butene; more preferably, the theoretical plate number of the extractive distillation column is 15 to 25; most preferably, the theoretical plate number of the extractive distillation column is 18 to 23.
According to the invention, the heptafluorobutene impurities in the octafluoro-2-butene crude product are removed by extractive distillation, 3-chloroheptafluoro-2-butene, 2, 3-dichloro-1, 4-hexafluoro-2-butene and octafluoro-2-butene dimer impurities in the octafluoro-2-butene crude product are removed by low-temperature rectification, and the preparation of the electronic grade octafluoro-2-butene product is realized by a combined mode of extractive distillation and low-temperature rectification.
The order of the extractive distillation and the low-temperature distillation can be arbitrary, namely, the extractive distillation can be carried out firstly and then the low-temperature distillation can be carried out, and the extractive distillation can be carried out firstly and then the low-temperature distillation can be carried out. However, it is preferable to carry a small amount of the extractant in the extractive distillation product, followed by extractive distillation and then cryogenic distillation.
In a specific embodiment, the method for purifying electronic grade octafluoro-2-butene comprises:
firstly, purifying and rectifying the crude octafluoro-2-butene product by adopting an extraction rectifying tower with the theoretical plate number of 10-80 to obtain an intermediate product stream, wherein after the extraction rectifying, the heptafluorobutene impurities are less than or equal to 5ppm;
and removing 3-chloroheptafluoro-2-butene, 2, 3-dichloro-1, 4-hexafluoro-2-butene, octafluoro-2-butene dimer and carried extractant in the intermediate product stream by adopting a low-temperature rectifying tower to obtain an electronic grade octafluoro-2-butene product.
The temperature of the tower bottom of the extraction rectifying tower is 30-100 ℃, the temperature of the tower top is 10-50 ℃, and the pressure is 0-300 kpa; the temperature of the tower bottom of the low-temperature rectifying tower is 10-50 ℃, the temperature of the tower top is-10-30 ℃, and the pressure is 0-100 kpa. Preferably, the temperature of the tower bottom of the extraction rectifying tower is 45-80 ℃, the temperature of the tower top is 30-40 ℃, and the pressure is 0-100 kpa; the temperature of the tower bottom of the low-temperature rectifying tower is 25-40 ℃, the temperature of the tower top is-10-15 ℃, and the pressure is 30-100 kpa.
The invention also provides a purifying device of the octafluoro-2-butene, which comprises:
the extracting agent and the octafluoro-2-butene crude product are contacted in the extracting and rectifying tower to remove heptafluorobutene impurities, so that an intermediate product stream with the heptafluorobutene impurities less than or equal to 100ppm is obtained; the extractant is at least one selected from esters, halogenated alkanes, amides, nitriles and alcohols.
And (3) feeding the intermediate product stream into the low-temperature rectifying tower to remove the carried extractant, and 3-chloroheptafluoro-2-butene, 2, 3-dichloro-1, 4-hexafluoro-2-butene and octafluoro-2-butene dimer impurities in the octafluoro-2-butene crude product to obtain a high-purity hexafluoro-2-butene product with the purity of more than or equal to 99.99 percent.
The theoretical plate number of the extractive distillation column is 10-80, preferably 15-25.
Further, the purifying apparatus further includes: and the extractant recovery tower is connected with the tower kettle of the extraction rectifying tower and is used for recovering the extractant, and the recovered extractant can be recycled to the extraction rectifying tower for reuse.
In a preferred embodiment, the extractant is preferably at least one selected from formamide, N-dimethylformamide, N-dimethylacetamide, acetonitrile and absolute ethanol.
In another preferred embodiment, the extractant is preferably at least one selected from the group consisting of a mixed extractant of acetonitrile and absolute ethanol, a mixed extractant of absolute ethanol and carbon tetrachloride, and a mixed extractant of acetonitrile and carbon tetrachloride.
Compared with the prior art, the invention has the beneficial effects that:
the invention adopts a purifying mode of combining extractive distillation and low-temperature distillation, not only realizes high removal rate of heptafluorobutene impurities by using an extracting agent with higher relative volatility, but also can obtain octafluoro-2-butene products with higher purity by using less equipment cost, and the purity of the products can reach 99.99 percent.
Drawings
FIG. 1 is a schematic diagram of an apparatus for purifying electronic grade octafluoro-2-butene according to example 3 of the present invention.
Detailed Description
The invention will be further illustrated with reference to the following specific examples, without limiting the invention to these specific embodiments. It will be appreciated by those skilled in the art that the invention encompasses all alternatives, modifications and equivalents as may be included within the scope of the claims.
The invention adopts an extraction rectification technology to separate and purify the crude octafluoro-2-butene containing heptafluorobutene impurities. Extractive distillation techniques are accomplished by varying the relative volatilities of octafluoro-2-butene and the near azeotrope. When the relative volatilities deviate from 1 and the greater the deviation, it is indicated that octafluoro-2-butene and near azeotrope are more easily separated; if the relative volatility is equal to 1, separation of octafluoro-2-butene and near azeotrope is not possible by ordinary fractional distillation separation.
The concept of relative volatility is proposed in engineering calculations in order to seek to represent the gas-liquid equilibrium relationship in a simple way. The volatility of the components in the solution is a function of temperature, so the concept of relative volatility is introduced. The ratio of the volatility of the volatile component to the volatility of the less volatile component in the solution, referred to as the relative volatility, is denoted by alpha AB Or alpha, the calculation formula is as follows:
α AB ＝(y A /x A )/(y B /x B )
wherein y is A Is the mass fraction of volatile components in the gas phase; y is B Is the mass fraction of the components which are difficult to volatilize in the gas phase; x is x A Is the mass fraction of volatile components in the liquid phase; x is x B Is the mass fraction of the components which are difficult to volatilize in the liquid phase.
When the extractant with the relative volatility more than 1 is adopted, the gas phase mass fraction of the octafluoro-2-butene is increased, and during extractive distillation, the octafluoro-2-butene in the gas phase is continuously concentrated at the top of the tower along with the increase of the tower height, so that the octafluoro-2-butene product without heptafluorobutene impurities is obtained.
The method comprises the steps of adopting an extractant with the relative volatility less than 1, increasing the mass fraction of a liquid phase of octafluoro-2-butene, concentrating octafluoro-2-butene in a gas phase in a tower kettle along with the reduction of the tower height during extraction and rectification, obtaining an electronic grade octafluoro-2-butene product at the tower top, obtaining a mixture of octafluoro-2-butene with small approximate azeotrope content and the extractant at the tower kettle, recycling the extractant through an extractant recycling tower, and recycling the recycled extractant to the extraction and rectification tower for repeated use.
Respectively adding different extractants into the crude octafluoro-2-butene product containing heptafluorobutene impurities, and calculating the relative volatilities of the octafluoro-2-butene and the heptafluorobutene impurities by utilizing the gas-liquid balance measurement results, wherein the results are shown in the following table 1:
TABLE 1 relative volatilities of octafluoro-2-butene and heptafluorobutene with different extractants
| Extraction agent | Relative volatility |
| Without any means for | 1.20 |
| Absolute ethyl alcohol | 2.58 |
| N, N-dimethylformamide | 1.45 |
| Anhydrous methanol | 1.85 |
| Acetonitrile | 2.18 |
| Dichloromethane (dichloromethane) | 1.31 |
| Cyclohexane | 1.28 |
| Carbon tetrachloride | 1.39 |
| Acetic acid ethyl ester | 0.91 |
| Acetonitrile, absolute ethanol=2:1 | 2.83 |
| Acetonitrile, absolute methanol=2:1 | 1.95 |
| Acetonitrile, carbon tetrachloride=2:1 | 2.08 |
Generally, when the relative volatility is greater than 1, the greater the relative volatility of octafluoro-2-butene and heptafluorobutene impurities, the greater the removal rate of heptafluorobutene impurities during extractive distillation.
Example 1
The embodiment provides a purification method of electronic grade octafluoro-2-butene, comprising the following steps:
s1, an extraction and rectification step: extracting and rectifying the crude octafluoro-2-butene product containing 6380ppm of heptafluoro-2-butene and heptafluoro-isobutylene by adopting an extraction and rectification tower with a theoretical plate number of 15 to obtain an intermediate product stream, wherein the mass ratio of an extracting agent to the crude octafluoro-2-butene product is 2:1, a step of;
the rectification parameters of the extraction rectification tower are as follows: the temperature of the tower bottom is 66 ℃, the temperature of the tower top is 35 ℃, and the pressure is 50kpa;
s2, a low-temperature rectification step: separating the intermediate product stream in a low-temperature rectifying tower to remove other impurities and carried extractant and obtain an electronic-grade octafluoro-2-butene product; the rectification parameters of the low-temperature rectification tower are as follows: the number of the tower plates is 15, the temperature of the tower bottom is 30 ℃, the temperature of the tower top is 10 ℃, and the pressure is 55kPa.
Extracting and rectifying by respectively adopting absolute ethyl alcohol, acetonitrile, a mixed extractant of acetonitrile and absolute ethyl alcohol and a mixed extractant of acetonitrile and carbon tetrachloride, collecting gas at the top of an extraction rectifying tower and octafluoro-2-butene products at the top of a low-temperature rectifying tower for gas chromatographic analysis, and calculating to obtain the removal rate of heptafluoro-2-butene impurities, wherein the results are shown in the following table 2:
TABLE 2 influence of different extractants on product purity
Example 2
The separation method of the embodiment adopts simulation evaluation: carrying out extractive distillation on an octafluoro-2-butene crude product containing heptafluoro-2-butene impurities, setting the temperature of the top of the tower to 35 ℃, setting the pressure to 50kpa, taking a mixed extractant of acetonitrile and absolute ethyl alcohol as an extractant as examples, wherein the content of heptafluoro-2-butene in the crude product is 6380ppm, the temperature of the bottom of a low-temperature rectifying tower is 30 ℃, the temperature of the top of the tower is 10 ℃, the pressure is 55kpa, changing the theoretical plate number of the extractive rectifying tower, and examining the influence of the theoretical plate number on the purification result, wherein the result is shown in the following table 3:
TABLE 3 influence of different theoretical plate numbers on the purity of the product
Note that: the rectification yield was calculated as 95%.
Example 3
The present embodiment provides a purification apparatus for electronic grade octafluoro-2-butene, as shown in fig. 1, the extraction and purification apparatus includes:
the method comprises the steps that an extraction rectifying tower T1, a theoretical plate number is 15, an octafluoro-2-butene crude product and an extractant 10 (the relative volatility is more than 1) enter the extraction rectifying tower T1 for separation, an intermediate product flow 11 is obtained at the top of the extraction rectifying tower, and an extractant 12 containing impurities is arranged at the bottom of the extraction rectifying tower;
a low-temperature rectifying tower T2, wherein the intermediate product flow 11 is separated in the low-temperature rectifying tower T2 to remove low-boiling-point substance impurities 13, an electronic-grade octafluoro-2-butene product 16 is obtained at the top of the low-temperature rectifying tower T3, and high-boiling-point substance impurities 14 in the crude product flow out of the tower kettle;
the extractant recovery tower T4 has a theoretical plate number of 10, the tower top is provided with heptafluorobutene impurities 17, and the extractant 15 recovered by the tower bottom is returned to the extraction rectifying tower T1 for use.
Example 4
The rectification parameters of the extraction rectification column in this embodiment are: the temperature of the tower top is 35 ℃, the temperature of the tower bottom is 65 ℃, the pressure is 52kpa, the theoretical plate number is 15, the mixed extractant of acetonitrile and absolute ethyl alcohol is taken as an extractant for example, the content of the heptafluorobutene impurities in the octafluoro-2-butene crude product is changed, the influence of the heptafluorobutene impurities on the purification result is examined by adopting simulation evaluation, and the result is shown in the following table 4:
TABLE 4 influence of different impurity contents on purification results
Example 5
The rectification parameters of the extraction rectification column in this embodiment are: the temperature of the tower top is 35 ℃, the temperature of the tower bottom is 65 ℃, the pressure is 52kpa, the theoretical plate number is 15, a mixed extractant of acetonitrile and absolute ethyl alcohol (acetonitrile: absolute ethyl alcohol=2:1) is used as the extractant, and the content of heptafluoro-2-butene in the crude product is 6380ppm; the effect of different tray numbers on the purification result was examined by simulation evaluation using the temperature of the bottom of the cryogenic rectification column at 30℃and the temperature of the top of the column at 10℃and the pressure at 55kpa, and the results are shown in Table 5 below.
TABLE 5 influence of different theoretical plate numbers on purification results
| Theoretical plate number of low-temperature rectifying tower | Product purity/% | Impurity removal rate/% |
| 10 | 99.89 | 99.59 |
| 15 | 99.95 | 99.92 |
| 20 | 99.99 | 99.99 |
Claims (10)
1. A method for purifying electronic grade octafluoro-2-butene is characterized in that: the purification method comprises the following steps:
and (3) an extraction and rectification step: extracting and rectifying the crude octafluoro-2-butene product in the presence of an extracting agent, wherein the extracting agent is at least one selected from ester compounds, halogenated alkanes, amide compounds, nitrile compounds and alcohol compounds;
a cryogenic rectification step;
the crude octafluoro-2-butene product comprises at least one of 3-chloroheptafluoro-2-butene, 2, 3-dichloro-1, 4-hexafluoro-2-butene, octafluoro-2-butene dimer and heptafluorobutene impurities; after the extraction and rectification step, the removal rate of the heptafluorobutene impurities is more than or equal to 99 percent.
2. The method for purifying electronic grade octafluoro-2-butene according to claim 1, characterized in that: the heptafluorobutene impurities comprise at least one of heptafluoro-1-butene, heptafluoro-2-butene and heptafluoroisobutylene.
3. The method for purifying electronic grade octafluoro-2-butene according to claim 1, characterized in that:
the ester compound is at least one selected from methyl formate, ethyl acetate and 3- (dimethylamino) ethyl acrylate;
the halogenated alkane is selected from at least one of dichloromethane, chloroform and carbon tetrachloride;
the amide compound is at least one selected from formamide, acetamide, propionamide, caproamide, N-dimethylformamide, N-dimethylacetamide, benzamide and succinimide;
the nitrile compound is at least one selected from acetonitrile, propionitrile and butyronitrile;
the alcohol compound is at least one selected from absolute ethyl alcohol, absolute methyl alcohol and isopropyl alcohol.
4. The method for purifying electronic grade octafluoro-2-butene according to claim 1, characterized in that: the extractant is a mixed extractant of acetonitrile and carbon tetrachloride, and the mass ratio of acetonitrile is 1% -99%.
5. The method for purifying electronic grade octafluoro-2-butene according to any of claims 1 to 4, characterized in that: the mass ratio of the extractant to the crude product containing octafluoro-2-butene is 0.5-100: 1.
6. the method for purifying electronic grade octafluoro-2-butene according to any of claims 1 to 4, characterized in that: the purification method specifically comprises the following steps:
firstly, purifying and rectifying the crude octafluoro-2-butene product by adopting an extraction rectifying tower with the theoretical plate number of 10-80 to obtain an intermediate product stream, wherein the concentration of heptafluorobutene impurities is less than or equal to 100ppm after the extraction rectifying;
and removing 3-chloroheptafluoro-2-butene, 2, 3-dichloro-1, 4-hexafluoro-2-butene, octafluoro-2-butene dimer and carried extractant in the intermediate product stream by adopting a low-temperature rectifying tower to obtain an electronic grade octafluoro-2-butene product.
7. The method for purifying electronic grade octafluoro-2-butene according to claim 6, characterized in that: the temperature of the tower bottom of the extraction rectifying tower is 30-100 ℃, the temperature of the tower top is 5-60 ℃ and the pressure is 0-300 kPa; the temperature of the tower bottom of the low-temperature rectifying tower is 10-50 ℃, the temperature of the tower top is-10-30 ℃, and the pressure is 0-100 kpa.
8. The utility model provides a purification device of electron level octafluoro-2-butene which characterized in that: the purification device comprises:
the method comprises the steps of (1) an extraction rectifying tower, wherein an extractant contacts with a crude octafluoro-2-butene product in the extraction rectifying tower to remove heptafluorobutene impurities, so as to obtain an intermediate product stream with the heptafluorobutene impurities less than or equal to 100ppm; the extractant is at least one selected from esters, halogenated alkanes, amides, nitriles and alcohols;
and (3) the intermediate product flow enters the low-temperature rectifying tower, 3-chloroheptafluoro-2-butene, 2, 3-dichloro-1, 4-hexafluoro-2-butene, octafluoro-2-butene dimer impurities and a carried extractant in the octafluoro-2-butene crude product are removed, and an electronic grade octafluoro-2-butene product with the purity of more than or equal to 99.99% is obtained.
9. The purification apparatus for electronic grade octafluoro-2-butene as claimed in claim 8, wherein: the purification device further comprises: and the extractant recovery tower is connected with the tower kettle of the extraction rectifying tower and is used for recovering the extractant.
10. The purification device of electronic grade octafluoro-2-butene according to claim 8 or 9, characterized in that: the extractant is at least one selected from formamide, N-dimethylformamide, N-dimethylacetamide, acetonitrile and absolute ethyl alcohol.
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