CN111072447A - Method for reducing acidity and moisture in fluorine-containing alkane - Google Patents
Method for reducing acidity and moisture in fluorine-containing alkane Download PDFInfo
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- CN111072447A CN111072447A CN201811220105.2A CN201811220105A CN111072447A CN 111072447 A CN111072447 A CN 111072447A CN 201811220105 A CN201811220105 A CN 201811220105A CN 111072447 A CN111072447 A CN 111072447A
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- 150000001335 aliphatic alkanes Chemical class 0.000 title claims abstract description 76
- 229910052731 fluorine Inorganic materials 0.000 title claims abstract description 75
- 239000011737 fluorine Substances 0.000 title claims abstract description 75
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 title claims abstract description 74
- 238000000034 method Methods 0.000 title claims abstract description 36
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 59
- 238000005406 washing Methods 0.000 claims abstract description 39
- 239000003513 alkali Substances 0.000 claims abstract description 37
- 239000002808 molecular sieve Substances 0.000 claims abstract description 33
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 claims abstract description 33
- 239000007787 solid Substances 0.000 claims abstract description 20
- 238000004108 freeze drying Methods 0.000 claims abstract description 13
- 238000001035 drying Methods 0.000 claims abstract description 12
- 238000001179 sorption measurement Methods 0.000 claims abstract description 10
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 63
- NBVXSUQYWXRMNV-UHFFFAOYSA-N monofluoromethane Natural products FC NBVXSUQYWXRMNV-UHFFFAOYSA-N 0.000 claims description 45
- 239000012043 crude product Substances 0.000 claims description 38
- 235000011121 sodium hydroxide Nutrition 0.000 claims description 21
- 238000005507 spraying Methods 0.000 claims description 20
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 12
- 239000007788 liquid Substances 0.000 claims description 7
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 6
- 239000012670 alkaline solution Substances 0.000 claims description 6
- 239000007864 aqueous solution Substances 0.000 claims description 2
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims description 2
- 239000000920 calcium hydroxide Substances 0.000 claims description 2
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims description 2
- 239000002253 acid Substances 0.000 abstract description 9
- 239000000047 product Substances 0.000 description 26
- 239000003518 caustics Substances 0.000 description 8
- 239000003507 refrigerant Substances 0.000 description 7
- NPNPZTNLOVBDOC-UHFFFAOYSA-N 1,1-difluoroethane Chemical compound CC(F)F NPNPZTNLOVBDOC-UHFFFAOYSA-N 0.000 description 6
- XPDWGBQVDMORPB-UHFFFAOYSA-N Fluoroform Chemical compound FC(F)F XPDWGBQVDMORPB-UHFFFAOYSA-N 0.000 description 6
- -1 halothane hydrocarbon Chemical class 0.000 description 6
- MSSNHSVIGIHOJA-UHFFFAOYSA-N pentafluoropropane Chemical compound FC(F)CC(F)(F)F MSSNHSVIGIHOJA-UHFFFAOYSA-N 0.000 description 6
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 5
- 239000002826 coolant Substances 0.000 description 5
- 239000011780 sodium chloride Substances 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
- 238000012856 packing Methods 0.000 description 4
- 238000005057 refrigeration Methods 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- LVGUZGTVOIAKKC-UHFFFAOYSA-N 1,1,1,2-tetrafluoroethane Chemical compound FCC(F)(F)F LVGUZGTVOIAKKC-UHFFFAOYSA-N 0.000 description 3
- AFYPFACVUDMOHA-UHFFFAOYSA-N chlorotrifluoromethane Chemical compound FC(F)(F)Cl AFYPFACVUDMOHA-UHFFFAOYSA-N 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- LCGLNKUTAGEVQW-UHFFFAOYSA-N Dimethyl ether Chemical compound COC LCGLNKUTAGEVQW-UHFFFAOYSA-N 0.000 description 2
- 239000002585 base Substances 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 125000004122 cyclic group Chemical group 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 239000012467 final product Substances 0.000 description 2
- 125000001153 fluoro group Chemical group F* 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- ZRNSSRODJSSVEJ-UHFFFAOYSA-N 2-methylpentacosane Chemical compound CCCCCCCCCCCCCCCCCCCCCCCC(C)C ZRNSSRODJSSVEJ-UHFFFAOYSA-N 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 1
- 239000005977 Ethylene Substances 0.000 description 1
- 229910021536 Zeolite Inorganic materials 0.000 description 1
- 238000010669 acid-base reaction Methods 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 150000002170 ethers Chemical class 0.000 description 1
- 229960003132 halothane Drugs 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 230000036632 reaction speed Effects 0.000 description 1
- 238000010992 reflux Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 239000010457 zeolite Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C17/00—Preparation of halogenated hydrocarbons
- C07C17/38—Separation; Purification; Stabilisation; Use of additives
- C07C17/383—Separation; Purification; Stabilisation; Use of additives by distillation
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C17/00—Preparation of halogenated hydrocarbons
- C07C17/38—Separation; Purification; Stabilisation; Use of additives
- C07C17/389—Separation; Purification; Stabilisation; Use of additives by adsorption on solids
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention discloses a method for reducing acidity and moisture in fluorine-containing alkane, which removes the acidity and the moisture in the fluorine-containing alkane through five steps of water alkali washing, freeze drying, solid alkali drying for removing acid and water, rectification and molecular sieve adsorption for removing water. The method provided by the invention can remove the acidity of the fluorine-containing alkane product to below 1ppm and remove the water content to below 10 ppm.
Description
Technical Field
The invention relates to a method for reducing acidity and moisture in products, in particular to a method for reducing acidity and moisture in fluorine-containing alkane.
Background
The fluorine-containing alkane, abbreviated as 'HFC', is an alkane containing fluorine atoms, and can be used as a refrigerant to replace CFC and HCFC for the refrigeration performance is close to that of CFC and HCFC. For example, HFC-41, also known as "monofluoromethane", "methyl fluoride" and "R41", is a novel compound among HFCs, is a colorless gas, is flammable, is easily soluble in alcohols, ethers and the like, has an ODP value of 0 and a GWP value of only 92, is excellent in environmental performance, and is a new-generation ODS substitute having a low GWP value. HFC-41 is expected to be used as a refrigerant for a refrigeration place originally using HFC-23 and CFC-13 instead of HFC-23 and CFC-13 because of its refrigeration performance close to HFC-23 and CFC-13 in addition to being used as an electronic gas.
When HFC is used as refrigerant, its product quality must meet the national standard of specific refrigerant, for example, when HFC-134a is used for refrigeration, its product must meet the national standard of industrial HFC-134a (GB/T18826-2002). When HFC-41 is used as a refrigerant, at present, although no special HFC-41 refrigerant national standard exists, the purity, acidity and moisture content of the product have specific standards by taking industrial HFC-134a national standard (GB/T18826-2002) as reference.
The current HFC-41 product is generally used as a raw material for synthesizing downstream products, and the product has the following characteristics: (1) the product purity is generally only more than 99.0 percent, and the product contains impurities such as dimethyl ether, ethylene and the like which are difficult to separate; (2) the trace acidic substances are difficult to remove in the product collection and purification processes, and the acidity in the final product is too high; (3) HFC-41 has small molecular weight, the molecular diameter is close to water molecules, the water control difficulty is higher than that of other fluorine-containing alkanes, and the water content in the final product is overhigh.
In the case of HFC-41, it is necessary to control the acidity and moisture content to reasonable levels in order to enable HFC-41 to be used as a refrigerant. Therefore, it is important to develop a method for reducing the acidity and moisture in the product containing fluoroalkanes.
Disclosure of Invention
The invention aims to provide a method for reducing acidity and moisture in a fluorine-containing alkane product, which can ensure that the acidity in the fluorine-containing alkane product is less than 1ppm and the moisture content is less than 10 ppm.
In the art, to remove moisture from the product, a drying process may be used. To remove the acidity in the product, a compound capable of reacting with the acid may be added to remove the acid. However, it is not common to combine various processes and the order of combining the processes in order to simultaneously remove moisture and acidity from a product, and the combination and order of combining the processes capable of removing moisture and acidity therefrom are generally different for different types of products.
In order to remove acidity and moisture in a halothane hydrocarbon product at the same time, the invention provides the following technical scheme:
a method of reducing acidity and moisture in a fluorine-containing alkane, the method comprising:
(1) carrying out water and alkali washing on the fluorine-containing alkane crude product to reduce the acidity of the fluorine-containing alkane crude product to below 5 ppm;
(2) freeze-drying the crude product of the fluorine-containing alkane obtained in the step (1) to reduce the water content in the crude product of the fluorine-containing alkane to below 2500 ppm;
(3) leading the crude product of the fluorine-containing alkane obtained in the step (2) to pass through a solid caustic soda dryer, so that the acidity of the crude product of the fluorine-containing alkane is reduced to below 1ppm, and the moisture content is reduced to below 800 ppm;
(4) rectifying the crude product of the fluorine-containing alkane obtained in the step (3) to obtain the crude product of the fluorine-containing alkane with the water content lower than 80 ppm;
(5) and (4) carrying out molecular sieve adsorption dewatering on the crude product of the fluorine-containing alkane obtained in the step (4) to obtain the fluorine-containing alkane with the water content lower than 10 ppm.
In the water alkali washing step, the acid in the fluorine-containing alkane crude product is subjected to a neutralization reaction with the alkali by adding the alkali liquor capable of chemically reacting with the acid, so as to remove the acid in the fluorine-containing alkane crude product.
The base used may be one commonly used in the art. As a preferred method, the alkaline wash is selected from aqueous solutions of sodium hydroxide and/or potassium hydroxide. The concentration of the alkaline solution can not only ensure that the acid in the fluorine-containing alkane crude product completely reacts, but also ensure that the dosage of the alkaline solution is too large, thus being not beneficial to environmental protection and cost economy. The mass concentration of the alkali wash liquid is preferably 2-5 wt%.
In order to promote the reaction of acid and alkali in the crude fluorine-containing alkane product and make the reaction complete, the invention preferably uses a spraying mode to carry out water-alkali washing. The aqueous caustic washing step may be carried out in a caustic tower, with the caustic wash liquid being added to the caustic tower in a cyclic spray by means of a spray means at the top of the caustic tower. After comprehensively considering the acid-base reaction speed, the completeness and the use amount of the alkaline solution, as a preferable mode, the spraying flow rate of the alkaline solution is 0.5-1.5 m3/h。
After the step of water alkali washing, the acidity of the crude product of the fluorine-containing alkane can be reduced to below 5 ppm.
The method provided by the invention can further remove free water in the fluorine-containing alkane crude product in the step of freeze drying. Generally, a freeze drying step is carried out, wherein the purity of the fluorine-containing alkane in the fluorine-containing alkane crude product is 80-95%, and the balance is mainly free water. After the step of freeze drying, the water content in the crude product containing the fluorine-containing alkane can be reduced to below 2500 ppm.
In the case of freeze-drying, as a preferable mode, the freeze-drying is performed in a spiral plate freeze-dryer and a tube freeze-dryer. The drying can be carried out by a spiral plate type freeze dryer firstly, a tubular type freeze dryer is carried out, or the drying can be carried out by the tubular type freeze dryer firstly and then the drying is carried out by the spiral plate type freeze dryer. Preferably, the freeze-dried powder is dried by a spiral plate freeze-dryer and then passes through a tubular freeze-dryer.
The cooling medium used in the spiral plate type freeze dryer and the tubular type freeze dryer can be low-temperature water or frozen saline water. The freeze drying temperature is preferably-20 to 0 ℃.
The air flow rate of the fluorine-containing alkane crude product entering a spiral plate type freeze dryer and a tubular freeze dryer is preferably 25-40 m3/h。
According to the method provided by the invention, after two steps of water alkali washing and freeze drying, the fluorine-containing alkane crude product is passed through a solid alkali dryer to further remove acidity and moisture content.
The solid caustic dryer is filled with a solid caustic, which is typically an inorganic caustic. Preferably, the solid base is at least one selected from the group consisting of solid sodium hydroxide, potassium hydroxide and calcium hydroxide.
After the crude product of the fluorine-containing alkane passes through the solid caustic soda dryer, the acidity of the crude product of the fluorine-containing alkane can be reduced to be below 1ppm, and the moisture content can be reduced to be below 800 ppm.
The method provided by the invention uses a rectification mode in the step (4) to further remove the water in the fluorine-containing alkane crude product. The fluorine-containing alkane can be collected by a return pipe, and part of water is retained in heavy components in the tower kettle in the form of high-boiling-point substances.
In order to remove the water in the fluorine-containing alkane crude product, a low-temperature and high-pressure rectification mode is adopted. As a preferable mode, the rectification temperature is 10-40 ℃. In a preferred embodiment, the distillation pressure is 0.5 to 3.0 MPa.
After the rectification step, the water content in the fluorine-containing alkane crude product can be reduced to be below 80 ppm.
The method provided by the invention finally carries out molecular sieve adsorption dewatering so as to further remove water in the fluorine-containing alkane crude product.
The molecular sieve used is preferably at least one selected from the group consisting of a 3A type molecular sieve, a 4A type molecular sieve and an XH type molecular sieve from the viewpoint of improving the moisture adsorption effect and efficiency. Namely: the zeolite can be one selected from 3A type molecular sieve, 4A type molecular sieve and XH type molecular sieve, can be two selected from 3A type molecular sieve, 4A type molecular sieve and XH type molecular sieve, and can be three selected from 3A type molecular sieve, 4A type molecular sieve and XH type molecular sieve.
In order to improve the water adsorption effect and efficiency, the 3A type molecular sieve, the 4A type molecular sieve and the XH type molecular sieve can be modified according to the common method in the field.
In the molecular sieve adsorption step, in order to remove the water content in the crude fluorine-containing alkane as much as possible, as a preferred mode, the crude fluorine-containing alkane is subjected to molecular sieve adsorption water removal in a circulating mode, namely: the crude product containing the fluorine alkane is circularly dried in a dryer filled with a molecular sieve. The cycle drying time is determined according to the water removal effect, and is generally 1 to 3 hours.
The method provided by the invention can effectively remove acidity and moisture in the fluorine-containing alkane crude product after water-alkali washing, freeze drying, solid-alkali drying for removing acid and water, rectification and molecular sieve adsorption for removing water, so as to obtain the fluorine-containing alkane product with the acidity less than 1ppm and the moisture content less than 10 ppm. Furthermore, the purity of the obtained fluorine-containing alkane product is generally over 99.99 percent.
The method provided by the invention is suitable for removing acidity and moisture in the fluorine-containing alkane crude product. The fluorine-containing alkane is the fluorine-containing alkane in the technical field and is an alkane containing fluorine atoms in molecules.
The method provided by the invention is particularly suitable for removing acidity and moisture in C1-C3 fluorine-containing alkane crude products. Is particularly suitable for removing acidity and moisture in monofluoromethane.
When the method of the present invention is used to remove acidity and moisture from monofluoromethane, the monofluoromethane may be prepared from methanol and HF as raw materials.
Detailed Description
The present invention is further illustrated by the following examples, which are not intended to limit the invention to these embodiments. It will be appreciated by those skilled in the art that the present invention encompasses all alternatives, modifications and equivalents as may be included within the scope of the claims.
Example 1
A crude fluoromethane was used, wherein: the purity of monofluoromethane was about 85%, the moisture content was about 0.3%, and the acidity was about 10 ppm.
The 800L water alkali washing tower is provided with 3 water alkali washing towers, polypropylene ring packing is arranged in the water alkali washing tower, and a spraying device is arranged at the top of the tower. The freeze dryer adopts frozen saline water with the temperature of-12 to-10 ℃ as a cooling medium. The solid caustic soda dryer is filled with cylindrical caustic soda blocks. The rectification pressure of the rectification tower is about 2.0MPa, and the rectification temperature is about 20 ℃.
Adding 500kg of NaOH solution with the mass concentration of 3% into an alkaline washing tower in a circulating spraying mode through an alkaline washing tower top spraying device, and adjusting the spraying flow of alkaline washing liquid to be 0.8m3Stabilization of the condensed oneThe mixed gas of the crude fluoromethane product is 25m3The gas velocity is sequentially passed through a water alkali washing tower, a freeze dryer and a solid alkali dryer, and then is compressed, condensed and collected to enter a rectifying tower, and the monofluoromethane with the purity of 99.98 percent is collected by a return pipe of the rectifying tower. And finally, introducing the monofluoromethane into an XH type molecular sieve for circulating drying for 2 hours to obtain a monofluoromethane product with 5ppm of water and 0.2ppm of acidity.
Example 2
A crude fluoromethane was used, wherein: the purity of monofluoromethane was about 90%, the moisture content was about 0.2%, and the acidity was about 8 ppm.
The 800L water alkali washing tower is provided with 3 water alkali washing towers, polypropylene ring packing is arranged in the water alkali washing tower, and a spraying device is arranged at the top of the tower. The freeze dryer adopts frozen saline water with the temperature of-10 to 0 ℃ as a cooling medium. The solid caustic soda dryer is filled with cylindrical caustic soda blocks. The rectification pressure of the rectification tower is about 2.0MPa, and the rectification temperature is about 25 ℃.
Adding 500kg of NaOH solution with the mass concentration of 3% into an alkaline washing tower in a circulating spraying mode through an alkaline washing tower top spraying device, and adjusting the spraying flow of alkaline washing liquid to be 1.5m3The reaction is stabilized, and the condensed crude product of the monofluoromethane mixed gas is 40m3The gas velocity is sequentially passed through a water alkali washing tower, a freeze dryer and a solid alkali dryer, and then is compressed, condensed and collected to enter a rectifying tower, and the monofluoromethane with the purity of 99.98 percent is collected by a return pipe of the rectifying tower. And finally, introducing the monofluoromethane into an XH type molecular sieve for circulating drying for 3 hours to obtain a monofluoromethane product with 8ppm of water and 0.7ppm of acidity.
Example 3
Crude difluoroethane was used, wherein: the difluoroethane had a purity of about 85%, a moisture content of about 0.4%, and an acidity of about 15 ppm.
The 800L water alkali washing tower is provided with 3 water alkali washing towers, polypropylene ring packing is arranged in the water alkali washing tower, and a spraying device is arranged at the top of the tower. The freeze dryer adopts frozen saline water with the temperature of-10 to 0 ℃ as a cooling medium. The solid caustic soda dryer is filled with cylindrical caustic soda blocks. The rectification pressure of the rectification tower is about 1.0MPa, and the rectification temperature is about 35 ℃.
Adding 500kg of NaOH solution with the mass concentration of 3% into an alkaline washing tower in a circulating spraying mode through an alkaline washing tower top spraying device,the spraying flow of the alkaline washing liquid is adjusted to be 1.2m3The reaction is stabilized, and the condensed crude difluoroethane mixed gas is cooled to 35m3The gas velocity is sequentially passed through a water alkali washing tower, a freeze dryer and a solid alkali dryer, and then is compressed, condensed and collected to enter a rectifying tower, and difluoroethane with the purity of 99.98 percent is collected by a return pipe of the rectifying tower. And finally, introducing the difluoroethane into an XH type molecular sieve for circulating drying for 3 hours to obtain a difluoroethane product with 5ppm of water and 0.4ppm of acidity.
Example 4
The crude pentafluoropropane used, wherein: the pentafluoropropane had a purity of about 95%, a moisture content of about 0.3%, and an acidity of about 12 ppm.
The 800L water alkali washing tower is provided with 3 water alkali washing towers, polypropylene ring packing is arranged in the water alkali washing tower, and a spraying device is arranged at the top of the tower. The freeze dryer adopts frozen saline water with the temperature of-10 to 0 ℃ as a cooling medium. The solid caustic soda dryer is filled with cylindrical caustic soda blocks. The rectification pressure of the rectification tower is about 0.6MPa, and the rectification temperature is about 35 ℃.
Adding 500kg of NaOH solution with the mass concentration of 3% into an alkaline washing tower in a circulating spraying mode through an alkaline washing tower top spraying device, and adjusting the spraying flow of alkaline washing liquid to be 1.5m3The condensed crude pentafluoropropane mixed gas is stabilized at a volume of 40m3The gas velocity/h sequentially passes through a water alkali washing tower, a freeze dryer and a solid alkali dryer, then is compressed, condensed and collected to enter a rectifying tower, and a reflux pipe of the rectifying tower collects pentafluoropropane with the purity of 99.98%. And finally, enabling the pentafluoropropane to enter an XH type molecular sieve for cyclic drying for 3 hours to obtain a pentafluoropropane product with 8ppm of moisture and 0.8ppm of acidity.
Claims (12)
1. A method for reducing acidity and moisture in a fluorine-containing alkane, the method comprising:
(1) carrying out water and alkali washing on the fluorine-containing alkane crude product to reduce the acidity of the fluorine-containing alkane crude product to below 5 ppm;
(2) freeze-drying the crude product of the fluorine-containing alkane obtained in the step (1) to reduce the water content in the crude product of the fluorine-containing alkane to below 2500 ppm;
(3) leading the crude product of the fluorine-containing alkane obtained in the step (2) to pass through a solid caustic soda dryer, so that the acidity of the crude product of the fluorine-containing alkane is reduced to below 1ppm, and the moisture content is reduced to below 800 ppm;
(4) rectifying the crude product of the fluorine-containing alkane obtained in the step (3) to obtain the crude product of the fluorine-containing alkane with the water content lower than 80 ppm;
(5) and (4) carrying out molecular sieve adsorption dewatering on the crude product of the fluorine-containing alkane obtained in the step (4) to obtain the fluorine-containing alkane with the water content lower than 10 ppm.
2. The method for reducing acidity and moisture in fluorine-containing alkane according to claim 1, wherein in the step (1), the water and alkali washing is carried out in a spraying manner, and the spraying flow rate of the alkali washing liquid is 0.5-1.5 m 3/h.
3. The method for reducing acidity and moisture in fluorine-containing alkane according to claim 2, wherein the alkaline solution is selected from an aqueous solution of sodium hydroxide and/or potassium hydroxide, and the concentration of the alkaline solution is 2 to 5 wt%.
4. The method for reducing acidity and moisture in fluorine-containing alkane according to claim 1, wherein in the step (2), the freeze-drying is performed in a spiral plate freeze-dryer and a tubular freeze-dryer at a freeze-drying temperature of-20 to 0 ℃.
5. The method for reducing acidity and moisture in fluorine-containing alkane according to claim 4, wherein in the step (2), the air velocity flow of the crude fluorine-containing alkane obtained in the step (1) entering the spiral plate type freeze dryer and the tubular type freeze dryer is 25-40 m3/h。
6. The method for reducing acidity and moisture in a fluorine-containing alkane according to claim 1, wherein in the step (3), the solid caustic soda dryer is filled with a solid caustic soda selected from at least one of solid sodium hydroxide, potassium hydroxide and calcium hydroxide.
7. The method for reducing acidity and moisture in fluorine-containing alkane according to claim 1, wherein in the step (4), the rectification temperature is 10 to 40 ℃ and the rectification pressure is 0.5 to 3.0 MPa.
8. The method for reducing acidity and moisture in a fluorine-containing alkane according to claim 1, wherein in the step (5), the molecular sieve is at least one selected from the group consisting of a 3A type molecular sieve, a 4A type molecular sieve and an XH type molecular sieve.
9. The method for reducing acidity and moisture in fluorine-containing alkane according to claim 8, wherein in the step (5), the crude fluorine-containing alkane obtained in the step (4) is subjected to molecular sieve adsorption water removal in a circulating manner, and the circulating drying time is 1-3 hours.
10. The method of reducing acidity and moisture in a fluorine-containing alkane according to claim 1, wherein the fluorine-containing alkane is a C1-C3 fluorine-containing alkane.
11. The method of reducing acidity and moisture in a fluorine-containing alkane according to claim 10, wherein the fluorine-containing alkane is monofluoromethane.
12. The method of reducing acidity and moisture in a fluoroalkane of claim 11, wherein the monofluoromethane is produced from methanol and HF.
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| CN111995492A (en) * | 2020-09-26 | 2020-11-27 | 安徽金禾实业股份有限公司 | Method for recovering solvent dichloromethane in acesulfame potassium production |
Citations (4)
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