CN113698270A - Process and system for stable production of difluoromethane - Google Patents
Process and system for stable production of difluoromethane Download PDFInfo
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- CN113698270A CN113698270A CN202110976052.2A CN202110976052A CN113698270A CN 113698270 A CN113698270 A CN 113698270A CN 202110976052 A CN202110976052 A CN 202110976052A CN 113698270 A CN113698270 A CN 113698270A
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- dichloromethane
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- hydrogen fluoride
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- RWRIWBAIICGTTQ-UHFFFAOYSA-N difluoromethane Chemical compound FCF RWRIWBAIICGTTQ-UHFFFAOYSA-N 0.000 title claims abstract description 66
- 238000000034 method Methods 0.000 title claims abstract description 41
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 30
- 230000008569 process Effects 0.000 title claims abstract description 23
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 claims abstract description 202
- 238000003682 fluorination reaction Methods 0.000 claims abstract description 54
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims abstract description 52
- 229910000040 hydrogen fluoride Inorganic materials 0.000 claims abstract description 52
- 239000003054 catalyst Substances 0.000 claims abstract description 42
- 239000007791 liquid phase Substances 0.000 claims abstract description 20
- VMPVEPPRYRXYNP-UHFFFAOYSA-I antimony(5+);pentachloride Chemical compound Cl[Sb](Cl)(Cl)(Cl)Cl VMPVEPPRYRXYNP-UHFFFAOYSA-I 0.000 claims abstract description 19
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 claims abstract description 16
- 230000006872 improvement Effects 0.000 claims abstract description 9
- 230000003197 catalytic effect Effects 0.000 claims abstract description 7
- 239000002994 raw material Substances 0.000 claims abstract description 6
- 239000006200 vaporizer Substances 0.000 claims description 26
- 238000006243 chemical reaction Methods 0.000 claims description 23
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims description 20
- 229910052801 chlorine Inorganic materials 0.000 claims description 20
- 239000000460 chlorine Substances 0.000 claims description 20
- 230000000694 effects Effects 0.000 abstract description 15
- 230000002035 prolonged effect Effects 0.000 abstract 1
- 238000010992 reflux Methods 0.000 description 13
- 229910021630 Antimony pentafluoride Inorganic materials 0.000 description 7
- DAMJCWMGELCIMI-UHFFFAOYSA-N benzyl n-(2-oxopyrrolidin-3-yl)carbamate Chemical compound C=1C=CC=CC=1COC(=O)NC1CCNC1=O DAMJCWMGELCIMI-UHFFFAOYSA-N 0.000 description 6
- VBVBHWZYQGJZLR-UHFFFAOYSA-I antimony pentafluoride Chemical compound F[Sb](F)(F)(F)F VBVBHWZYQGJZLR-UHFFFAOYSA-I 0.000 description 5
- 229910052787 antimony Inorganic materials 0.000 description 4
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 description 3
- 125000001153 fluoro group Chemical group F* 0.000 description 3
- 239000012071 phase Substances 0.000 description 3
- GUNJVIDCYZYFGV-UHFFFAOYSA-K Antimony trifluoride Inorganic materials F[Sb](F)F GUNJVIDCYZYFGV-UHFFFAOYSA-K 0.000 description 2
- XWCDCDSDNJVCLO-UHFFFAOYSA-N Chlorofluoromethane Chemical compound FCCl XWCDCDSDNJVCLO-UHFFFAOYSA-N 0.000 description 2
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 2
- DBUQEYQQFXCLAW-UHFFFAOYSA-N [Sb].ClF Chemical compound [Sb].ClF DBUQEYQQFXCLAW-UHFFFAOYSA-N 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 229910052731 fluorine Inorganic materials 0.000 description 2
- 239000011737 fluorine Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- VXNJSWAPZBCJCG-UHFFFAOYSA-I trichloro(difluoro)-$l^{5}-stibane Chemical compound F[Sb](F)(Cl)(Cl)Cl VXNJSWAPZBCJCG-UHFFFAOYSA-I 0.000 description 2
- BGJSXRVXTHVRSN-UHFFFAOYSA-N 1,3,5-trioxane Chemical compound C1OCOCO1 BGJSXRVXTHVRSN-UHFFFAOYSA-N 0.000 description 1
- OHMHBGPWCHTMQE-UHFFFAOYSA-N 2,2-dichloro-1,1,1-trifluoroethane Chemical compound FC(F)(F)C(Cl)Cl OHMHBGPWCHTMQE-UHFFFAOYSA-N 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 1
- 241000695274 Processa Species 0.000 description 1
- FAPDDOBMIUGHIN-UHFFFAOYSA-K antimony trichloride Chemical compound Cl[Sb](Cl)Cl FAPDDOBMIUGHIN-UHFFFAOYSA-K 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 238000012824 chemical production Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 1
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 1
- 238000007327 hydrogenolysis reaction Methods 0.000 description 1
- 230000002779 inactivation Effects 0.000 description 1
- 230000002427 irreversible effect Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000001172 regenerating effect Effects 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- WFAQDDWJNRMULW-UHFFFAOYSA-I tetrachloro(fluoro)-$l^{5}-stibane Chemical compound F[Sb](Cl)(Cl)(Cl)Cl WFAQDDWJNRMULW-UHFFFAOYSA-I 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 239000012808 vapor phase Substances 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C17/00—Preparation of halogenated hydrocarbons
- C07C17/093—Preparation of halogenated hydrocarbons by replacement by halogens
- C07C17/20—Preparation of halogenated hydrocarbons by replacement by halogens of halogen atoms by other halogen atoms
- C07C17/202—Preparation of halogenated hydrocarbons by replacement by halogens of halogen atoms by other halogen atoms two or more compounds being involved in the reaction
- C07C17/206—Preparation of halogenated hydrocarbons by replacement by halogens of halogen atoms by other halogen atoms two or more compounds being involved in the reaction the other compound being HX
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/0006—Controlling or regulating processes
Abstract
The invention discloses a stable production process and a system of difluoromethane, wherein the process takes dichloromethane and hydrogen fluoride as raw materials to carry out liquid phase fluorination under the catalytic action of antimony pentachloride, and the liquid phase fluorination comprises the following improvement procedures: the improvement procedure comprises the steps of adding dichloromethane and anhydrous hydrogen fluoride into a reactor in proportion, stopping adding hydrogen fluoride and continuing to add dichloromethane into the reactor; and/or, adding chlorine gas during the liquid phase fluorination. The excessive addition of the dichloromethane avoids the over fluorination of the antimony pentachloride, and the addition of the chlorine gas keeps the activity of the catalyst, so that the running period of the stable production of the difluoromethane can be greatly prolonged.
Description
Technical Field
The invention belongs to the technical field of fluorine chemical production, and relates to a stable production process and system of difluoromethane.
Background
The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.
The synthesis process of difluoromethane mainly includes dichloromethane fluorination processA hydrochlorofluorocarbon hydrogenolysis reduction method, a formaldehyde fluorination method, a trioxane method, and the like. The dichloromethane fluorination method comprises a liquid phase method, a gas phase method and a segmented continuous fluorination method. Wherein, the liquid phase method mainly takes methylene chloride and anhydrous hydrogen fluoride as raw materials to carry out fluorination under the catalytic action of antimony pentachloride. In the reaction process, antimony pentachloride can react with hydrogen fluoride to generate antimony chlorofluoride (SbCl)5-nFnIn, SbCl4F has the strongest fluorination activity, and the dichloromethane can be separated into two steps (the first step is that the dichloromethane reacts with HF to generate monochloro-fluoro methane, and the second step is that the monochloro-fluoro methane continuously reacts with HF to generate difluoromethane) and SbCl4F, carrying out fluorination reaction to finally generate difluoromethane, and regenerating antimony pentachloride serving as a catalyst.
The inventor finds that the existing dichloromethane liquid phase fluorination method generally needs to replace the catalyst every year, the operation period is short, and the consumption of the catalyst is large in the actual production process. Therefore, how to stably produce difluoromethane, improve stable operation, reduce consumption, and ensure long-period stable operation of difluoromethane device is a problem that needs to be solved by those skilled in the art.
Disclosure of Invention
Under the condition of excessive hydrogen fluoride, antimony monofluorotetrachloride can continuously react with hydrogen fluoride to generate antimony difluorotrichloride SbCl3F2Antimony trifluoride SbCl2F3Antimony tetrafluoro monochloride SbClF4And antimony pentafluoride SbF5. The inventor combines the actual production with the theoretical research to find that the more fluorine atoms in the antimony chlorofluoride, the more stable the combination of fluorine and antimony, the difficult fluorination reaction of the fluorine atoms and dichloromethane, the poor catalytic activity, and the irreversible fluorination of the catalyst because the antimony pentachloride can not be regenerated because the fluorination reaction of the fluorine atoms and dichloromethane can not be carried out. Thus resulting in the need for periodic catalyst replacement.
In order to solve the defects of the prior art, the invention aims to provide a process and a system for stable production of difluoromethane, wherein the process can greatly improve the operation period of stable production of difluoromethane.
In order to achieve the purpose, the technical scheme of the invention is as follows:
on the one hand, the stable production process of difluoromethane uses dichloromethane and hydrogen fluoride as raw materials to carry out liquid phase fluorination under the catalytic action of antimony pentachloride, and the liquid phase fluorination comprises the following improved procedures:
the improvement procedure comprises the steps of adding dichloromethane and anhydrous hydrogen fluoride into a reactor in proportion, stopping adding hydrogen fluoride and continuing to add dichloromethane into the reactor;
and/or, adding chlorine gas during the liquid phase fluorination.
In actual production, after hydrogen fluoride and dichloromethane in a reaction kettle enter a reactor according to a feeding ratio, the hydrogen fluoride reacts or is heated to volatilize in an excessive dichloromethane environment. When the feeding of the reactor is stopped, after the addition of the hydrogen fluoride is stopped, the dichloromethane is continuously added to ensure the excessive dichloromethane in the reactor. The hydrogen fluoride can not be stored in the reaction kettle for a long time in a large amount, so that the over-fluorination of the antimony pentachloride is avoided.
In addition, antimony difluorotrichloride (SbCl)3F2) Is easy to decompose to generate antimony trichloride which has no catalytic action. The invention adds chlorine gas in the liquid phase fluorination process, so that the reaction system keeps the chlorine gas oxidation environment, and when antimony trichloride is generated, antimony pentachloride is immediately oxidized by the chlorine gas, thereby keeping the activity of the catalyst.
The excessive addition of dichloromethane avoids the over-fluorination of antimony pentachloride, and the addition of chlorine gas keeps the activity of the catalyst, thereby improving the stable operation and reducing the consumption.
In order to realize the process, on the other hand, the system for stably producing the difluoromethane comprises a reactor, wherein a feed inlet of the reactor is simultaneously connected with a dichloromethane source and a hydrogen fluoride source;
the reactor also comprises a chlorine pipeline which is communicated with the reactor and a chlorine source.
According to the invention, chlorine can be continuously added into the reactor through the addition of the chlorine pipeline, so that the influence of antimony trichloride on the activity of the catalyst is avoided.
The invention has the beneficial effects that:
1. the excessive addition of the dichloromethane prevents the transition fluorination of the catalyst, and the addition of the chlorine gas oxidizes the generated antimony trichloride to keep the activity of the catalyst, so that the control and the simple improvement of a pipeline are only carried out under the condition of not changing the main process, the long-period stable operation of the difluoromethane production process is improved to more than 3 years from the original operation for 1 year.
2. The method controls and adds the chlorine pipeline only by adding amount of the dichloromethane, has small improvement range of a main process system and low cost, and is easy to realize when being applied to enterprise production.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.
FIG. 1 is a schematic structural view of a system for the stable production of difluoromethane in example 1 of the present invention;
FIG. 2 is a schematic structural view of a system for the stable production of difluoromethane in example 2 of the present invention;
the system comprises a fluorination reactor 1, a reflux tower 2, a dichloromethane vaporizer 3, a HF vaporizer 4, a chlorine compressor 5, a dichloromethane pump 6, an HF pump 7, an HF pump 8 and a catalyst pump.
Detailed Description
It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
The process is based on the volume of a fluorination reactor being 4-10 m3The process for producing difluoromethane.
In view of the problem that the stable operation period is short in the conventional liquid phase fluorination method for producing dichloromethane, the invention provides a stable production process and system for difluoromethane.
The invention provides a typical embodiment of a stable production process of difluoromethane, which takes dichloromethane and hydrogen fluoride as raw materials to carry out liquid phase fluorination under the catalysis of antimony pentachloride, wherein the liquid phase fluorination comprises the following improved procedures:
the improvement procedure comprises the steps of adding dichloromethane and hydrogen fluoride into a reactor in proportion, stopping adding anhydrous hydrogen fluoride, and continuing to add dichloromethane into the reactor;
and/or, adding chlorine gas during the liquid phase fluorination.
According to the invention, when the feeding of the reactor is stopped, the dichloromethane is continuously added after the hydrogen fluoride is stopped, so that the excessive dichloromethane in the reactor is ensured. The hydrogen fluoride can not be stored in the reaction kettle for a long time in a large amount, so that the over-fluorination of the antimony pentachloride is avoided.
The invention adds chlorine gas in the liquid phase fluorination process, so that the reaction system keeps the chlorine gas oxidation environment, and when antimony trichloride is generated, antimony pentachloride is immediately oxidized by the chlorine gas, thereby keeping the activity of the catalyst. The reaction formula is as follows: cl2+SbCl3→SbCl5。
In some examples of the embodiment, the mass ratio of dichloromethane to hydrogen fluoride fed into the reactor during the reaction is 1.85-2.2: 1.
In some examples of this embodiment, the hydrogen fluoride addition is stopped and the addition of dichloromethane to the reactor is continued in an amount of 400 to 600 kg. The aim is to finish the reaction of the redundant hydrogen fluoride in the reactor and prevent the redundant hydrogen fluoride from reacting with the antimony pentachloride catalyst to cause over fluorination and inactivation.
In some examples of this embodiment, the chlorine gas is added at a rate of 4 to 5 kg/h.
Through productionIt was found that even though the time for maintaining the activity of the catalyst can be increased by the above-described manner, there is still a problem that the conversion rate is decreased, and thus in some examples of this embodiment, the catalyst is replenished when the conversion rate is less than 95%. This is due to the fact that after a long reaction time, a small portion of the antimony pentachloride is converted into antimony tetrafluoro monochloride SbClF4And antimony pentafluoride SbF5Resulting in a decrease in catalyst activity, and thus when the conversion is less than 95%, it is shown that antimony tetrafluoro monochloride SbClF4And antimony pentafluoride SbF5Starts to increase and starts to affect the conversion rate, so that the catalyst is replenished at this time, the activity of the catalyst can be maintained smoothly, and stable production can be further achieved.
In some examples of this embodiment, the liquid phase fluorination pressure is 1.1 to 1.3MPa and the temperature is 85 to 95 ℃.
In order to realize the process, the invention provides a system for stably producing difluoromethane, which comprises a reactor, wherein a feed inlet of the reactor is simultaneously connected with a dichloromethane source and a hydrogen fluoride source;
the reactor also comprises a chlorine pipeline which is communicated with the reactor and a chlorine source.
According to the invention, chlorine can be continuously added into the reactor through the addition of the chlorine pipeline, so that the influence of antimony trichloride on the activity of the catalyst is avoided.
Some examples of this embodiment include a catalyst makeup line that communicates between the reactor and the catalyst source. A small amount of catalyst can be added into the reactor, thereby ensuring the stability of the activity of the catalyst.
Some examples of this embodiment include a methylene chloride vaporizer, an inlet of the methylene chloride vaporizer connected to a methylene chloride source, and an outlet of the methylene chloride vaporizer connected to a feed inlet of the reactor. The methylene dichloride is preheated by the methylene dichloride vaporizer, so that the temperature rise time in the reactor is reduced, and the reaction efficiency is improved.
In one or more embodiments, the outlet of the catalyst make-up line is connected to the inlet of the methylene chloride vaporizer. The catalyst is preheated by the dichloromethane vaporizer, so that the temperature fluctuation of the reactor in the catalyst replenishing process is prevented, and the influence on the reaction stability is avoided.
Some examples of this embodiment include a hydrogen fluoride vaporizer having an inlet connected to a source of hydrogen fluoride and an outlet connected to the feed inlet of the reactor. The hydrogen fluoride is preheated by the hydrogen fluoride vaporizer, so that the temperature rise time in the reactor is reduced, and the reaction efficiency is increased. In addition, the outlet of the catalyst replenishing pipeline is connected with the inlet of the dichloromethane vaporizer instead of the hydrogen fluoride vaporizer, and the reason is that the catalyst is antimony pentachloride which is easy to react with hydrogen fluoride and generate antimony pentafluoride more easily, so that the catalytic activity of the catalyst is influenced, and hydrogen fluoride in the hydrogen fluoride vaporizer is easy to remain, and if the hydrogen fluoride vaporizer passes through the hydrogen fluoride vaporizer, the hydrogen fluoride is easy to react with the remaining hydrogen fluoride, so that the activity of the replenished catalyst is influenced.
Some examples of this embodiment include a reflux column having a vapor phase outlet connected to a reflux column inlet and a bottom outlet connected to a recycle inlet of the reactor. The generated hydrogen chloride is separated from a small amount of unreacted hydrogen fluoride through the reflux tower, and the hydrogen fluoride is recycled, so that the consumption of the hydrogen fluoride is reduced.
In order to make the technical solutions of the present invention more clearly understood by those skilled in the art, the technical solutions of the present invention will be described in detail below with reference to specific embodiments.
The fluorination reactor used in the following examples had a volume of 10m3In the production process, the feeding amount is equal to the discharging amount, and the volume of the material in the fluorination reactor is kept to be one half of the volume of the fluorination reactor.
Example 1
A system for stably producing difluoromethane is shown in figure 1 and comprises a fluorination reactor 1 and a reflux tower 2, wherein the reflux tower 2 is arranged at the top of the fluorination reactor 1, a gas phase outlet of the fluorination reactor 1 is connected with an inlet of the reflux tower 2, and a tower bottom outlet of the reflux tower 2 is connected with a circulating inlet of the fluorination reactor 1.
The inlet of the fluorination reactor 1 is connected with a chlorine pipeline, a dichloromethane pipeline and a hydrogen fluoride pipeline. The chlorine pipeline is provided with a chlorine compressor 5. The methylene chloride line is provided with a methylene chloride pump 6 and a methylene chloride vaporizer 3 in this order in the flow direction. The hydrogen fluoride line is provided with an HF pump 7 and an HF vaporizer 4 in this order in the flow direction of the fluid.
The process comprises the following steps: dichloromethane and anhydrous hydrogen fluoride are respectively metered by a delivery pump according to the proportion of 1.85-2.2: 1, are heated and then enter a fluorination reactor together for reaction (the reaction pressure is 1.2MPa, the temperature is 90 ℃), and chlorine is supplemented by a diaphragm compressor according to 4-5 kg per hour to maintain the oxidation environment in the fluorination reactor.
Example 2
A system for stably producing difluoromethane is shown in figure 2 and comprises a fluorination reactor 1 and a reflux tower 2, wherein the reflux tower 2 is arranged at the top of the fluorination reactor 1, a gas phase outlet of the fluorination reactor 1 is connected with an inlet of the reflux tower 2, and a tower bottom outlet of the reflux tower 2 is connected with a circulating inlet of the fluorination reactor 1.
The inlet of the fluorination reactor 1 is connected with a chlorine pipeline, a dichloromethane pipeline and a hydrogen fluoride pipeline. The chlorine pipeline is provided with a chlorine compressor 5. The methylene chloride line is provided with a methylene chloride pump 6 and a methylene chloride vaporizer 3 in this order in the flow direction. The inlet of the dichloromethane vaporizer 3 is also connected with a catalyst replenishing pipeline, and a catalyst pump 8 is arranged on the catalyst replenishing pipeline. The hydrogen fluoride line is provided with an HF pump 7 and an HF vaporizer 4 in this order in the flow direction of the fluid.
In the process, raw materials of dichloromethane and hydrogen fluoride respectively pass through a dichloromethane pump and an HF pump, then respectively enter a dichloromethane vaporizer and an HF vaporizer, finally enter a fluorination reactor for reaction (the reaction pressure is 1.2MPa, the temperature is 90 ℃), process gas with heavy components separated out by a reflux tower enters a rear system, and chlorine gas is constantly supplemented by a chlorine gas compressor to maintain the oxidation environment in the fluorination reactor; when the activity of the catalyst is found to be poor (the conversion rate in the reactor is less than 95 percent), starting a catalyst pump, and quantitatively adding 500kg of antimony pentachloride catalyst to maintain the activity of the catalyst in the kettle; when the system was shut down, 500kg of dichloromethane was added to maintain an excess to prevent over-fluorination.
The production process of the embodiment can increase the original stabilization time from 1 year to more than 3 years, and simultaneously the conversion rate can be kept more than 97 percent.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A stable production process of difluoromethane uses dichloromethane and hydrogen fluoride as raw materials to carry out liquid phase fluorination under the catalytic action of antimony pentachloride, and is characterized in that the liquid phase fluorination comprises the following improvement procedures:
the improvement procedure comprises the steps of adding dichloromethane and hydrogen fluoride into a reactor in proportion, stopping adding anhydrous hydrogen fluoride, and continuing to add dichloromethane into the reactor;
and/or, adding chlorine gas during the liquid phase fluorination.
2. The process for the stable production of difluoromethane as claimed in claim 1, wherein the feed ratio of dichloromethane and hydrogen fluoride into the reactor is 1.85-2.2: 1.
3. A process for the stable production of difluoromethane according to claim 1, wherein the addition of hydrogen fluoride is stopped and the addition of dichloromethane is continued in an amount of 500kg to the reactor.
4. A process for the stable production of difluoromethane as claimed in claim 1, wherein the rate of addition of chlorine is 4-5 kg/h.
5. A process for the stable production of difluoromethane according to claim 1, wherein the catalyst is replenished when the conversion is less than 95%.
6. The process for the stable production of difluoromethane as claimed in claim 1, wherein the pressure of liquid phase fluorination is 1.1-1.3 MPa and the temperature is 85-95 ℃.
7. A system for stably producing difluoromethane comprises a reactor, wherein a feed inlet of the reactor is simultaneously connected with a dichloromethane source and a hydrogen fluoride source;
the device is characterized by also comprising a chlorine pipeline which is communicated with the reactor and a chlorine source.
8. A system for the stable production of difluoromethane according to claim 7, comprising a catalyst make-up line communicating between the reactor and the source of catalyst.
9. A system for the stable production of difluoromethane as claimed in claim 7, comprising a dichloromethane vaporizer, wherein the inlet of the dichloromethane vaporizer is connected to a dichloromethane source, and the outlet of the dichloromethane vaporizer is connected to the feed inlet of the reactor.
10. A system for the stable production of difluoromethane as in claim 9, wherein the outlet of said catalyst make-up line is connected to the inlet of a methylene chloride vaporizer.
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