Method and device for producing monochlorodifluoromethane by segmented method

Abstract

The invention provides a method and a device for producing monochlorodifluoromethane by a segmented method, and the method comprises the following steps: (1) catalyst reaction: introducing SbCl5 into a SbCl5 temporary storage tank, when liquid in the SbCl5 temporary storage tank overflows into a catalyst reaction kettle, adding AHF to generate a catalyst SbCl4F and HCl in the catalyst reaction kettle, when the liquid level of the catalyst reaction kettle reaches an overflow position and the liquid level of the catalyst temporary storage tank reaches a specified position, starting to pump a catalyst into the R22 reaction kettle; (2) fluorination reaction: starting chloroform fluorination reaction on the catalyst and chloroform in an R22 reaction kettle, introducing CHClF2 gas into a subsequent refining system for refining to obtain a CHClF2 product, and overflowing the used catalyst into a SbCl5 temporary storage tank; and (3) continuous operation of the reaction: when CHClF2 overflows into the SbCl5 temporary storage tank, stopping introducing the SbCl5, adjusting process parameters, and starting continuous operation of the system. The method provided by the invention avoids the problem of generation of waste hydrofluoric acid, shortens the retention time of organic matters in the reaction kettle, reduces the occurrence of side reactions, and relieves the environmental protection pressure of the system.

Description

Technical Field

[0001] The invention relates to a method and a device for producing chlorodifluoromethane by a segmented method, belonging to the field of refrigerants. Background Art

[0002] Difluorochloromethane is a colorless gas with a slightly sweet smell and low toxicity. It is often used as a refrigerant and aerosol insecticide propellant. The liquid phase method of producing difluorochloromethane (F22) using chloroform and AHF as raw materials has the following reaction principle: SbCl5+HFSbCl4F+HCl(1) SbCl4F+CHCl3SbCl5+CHCl2F(2) SbCl4F+CHCl2F→SbCl5+CHClF2(3) SbCl4F+CHClF2→SbCl5+CHF3(4) Among them, reactions (1) and (2) are fast reversible reactions, especially reaction (1), which can quickly reach equilibrium at room temperature. Reactions (3) and (4) react slowly. The reaction rate ratio of reactions (1) to (4) is about 150.0:7.0:1.0:0.037.

[0003] At present, R22 is produced by the reaction of chloroform and AHF, and its process flow is as follows: chloroform (CHCl3) and AHF undergo liquid-phase fluorination reaction in a fluorination reactor through the action of a catalyst to generate product R22, and at the same time generate monofluorodichloromethane (R21), trifluoromethane (R23) and by-product hydrogen chloride (HCl), which belongs to the "one-pot" reaction process; the reaction product, a small amount of catalyst and unreacted AHF and CHCl3 enter the reflux tower, and by using the principle of fractionation, a large amount of R21, CHCl3, HF and part of R22 return to the reactor, and the reaction gas mainly containing R22 and HCl and a small amount of HF, R21 and R23 enters the subsequent HCl distillation unit; using low Warm dry separation, in the HCl distillation tower, separate the light components HCl, R23 and the heavy components R22, R21, HF; the light components are made into 31% hydrochloric acid and non-condensable gas R23 (sent to the incineration system for treatment) through the falling film absorption tower; the heavy components are washed and separated in the aqueous acid tower to obtain about 12% aqueous acid (containing about 12% HF and about 0.3%~3% HCl) and HF-free crude products; the HF-free crude products are introduced into the alkali washer for washing and separation with NaOH, and the alkaline wastewater is discharged. The alkali-washed crude products are sent to the product refining system for treatment, and the R22 product and R21 intermediate are separated. R21 is sent to the fluorination reactor for further reaction. The aqueous acid containing hydrochloric acid is mainly used in the production of fluoride salts. The above one-pot method for producing difluorochloromethane has the following problems: (1) The above technology produces a repeated process of washing and drying organic matter; (2) There is a problem with the disposal of waste hydrofluoric acid. With the increasing demand for fluoride salt products, the use of this hydrofluoric acid is becoming less and less. At present, it is generally treated as waste acid, which puts great pressure on the environment and has high costs for waste acid treatment, and also causes serious waste of fluorine resources. Summary of the invention

[0004] The present invention provides a method and device for producing difluoromonochloromethane by a staged process, which avoids the repeated process of washing and drying organic matter, avoids the problem of waste hydrofluoric acid generation, shortens the residence time of organic matter in a reactor, reduces the occurrence of side reactions, reduces production material consumption, and alleviates the environmental protection pressure of the system.

[0005] The technical solution adopted by the present invention is: A method for producing monochlorodifluoromethane by a staged process comprises the following steps: (1) Catalyst reaction: SbCl5 is introduced into the SbCl5 temporary storage tank. When the liquid in the SbCl5 temporary storage tank reaches a certain level, it overflows into the catalyst reactor. AHF is added to generate catalyst SbCl4F and HCl in the catalyst reactor. When the liquid level of the catalyst reactor reaches the overflow position, the catalyst overflows into the catalyst temporary storage tank. The trace HF and HCl in the catalyst temporary storage tank are recycled. When the liquid level of the catalyst temporary storage tank reaches the specified position, the catalyst is pumped to the R22 reactor. (2) Fluorination reaction: The catalyst and chloroform start to carry out chloroform fluorination reaction in the R22 reactor, and the generated reaction gas (CHClF2, carrying a small amount of CHCl2F and CHCl3) enters the R21 reflux tower, and after fractionation, CHClF2 and CHCl3 are refluxed into the reactor to continue to participate in the reaction. The CHClF2 gas is introduced into the subsequent refining system for refining to obtain the CHClF2 product, and the other part overflows into the SbCl5 temporary storage tank. The trace amount of CHCl3 and CHCl2F in the SbCl5 temporary storage tank is introduced into the R21 reflux tower for fractionation; (3) Continuous operation of the reaction: When material overflows from the R22 reactor into the SbCl5 temporary storage tank, stop introducing SbCl5, adjust the AHF delivery rate to the CHCl3 delivery rate (the mol ratio of AHF to CHCl3 is 2:1), adjust the R22 reactor temperature, R21 reflux tower temperature and pressure, catalyst reactor temperature, HF reflux tower temperature and pressure to the process setting range, and the system starts to run continuously.

[0006] Furthermore, preferably: the step (1) is specifically: (1.1) Antimony pentachloride is pumped into the SbCl5 temporary storage tank. When the liquid level reaches a certain level, SbCl5 begins to overflow into the catalyst reactor; (1.2) When SbCl5 begins to overflow into the catalyst reactor, open the HF reflux tower; (1.3) When the SbCl5 liquid level is higher than the outlet of the AHF feeding pipe, start the AHF delivery pump and add AHF according to the molar amount of SbCl5. When the liquid level of the catalyst reactor reaches the overflow position and the liquid level of the catalyst temporary storage tank reaches the specified position, start pumping the catalyst to the R22 reactor; (1.4) The catalyst overflowing into the catalyst temporary storage tank carries trace amounts of HF and HCl, which escape from the temporary storage tank and are introduced into the HF reflux tower for fractionation. HF refluxes into the catalyst reactor to continue participating in the reaction; (1.5) When the catalyst begins to overflow into the catalyst temporary storage tank, start to continuously introduce a small amount of chlorine gas into the bottom of the catalyst reactor to ensure that the trace amount of SbCl3 in SbCl5 is converted into SbCl5; (1.6) The HCl generated by the reaction carries a small amount of HF, which is fractionated in the HF reflux tower. The HF returns to the catalyst reactor to continue the reaction, and the HCl is sent to the HCl absorption system to produce a hydrochloric acid solution of a certain concentration.

[0007] Further, preferably: the step (2) is specifically: (2.1) When the catalyst begins to be pumped into the R22 reactor, start the R21 reflux tower and the R22 reactor heating system; (2.2) When the liquid level of the R22 reactor reaches 50%, chloroform is pumped into the R22 reactor to start the chloroform fluorination reaction. The R22 generated by the reaction carries a small amount of R21 and CHCl3. In the R21 reflux tower, R21 and CHCl3 are refluxed into the R22 reactor after fractionation to continue participating in the reaction; (2.3) The R22 gas discharged from the top of the R21 reflux tower is introduced into the R22 refining system (the R22 refining system in the original system) to produce R22 products and recover unreacted R21; (2.4) The SbCl5 that overflows into the SbCl5 temporary storage tank carries trace amounts of R21 and CHCl3, escapes from the temporary storage tank and is introduced into the R21 reflux tower for fractionation, and then returns to the R22 reactor to continue the reaction.

[0008] Further, preferably: the step (3) is specifically: (3.1) When the R22 reactor reaches the overflow level and begins to overflow into the SbCl5 temporary storage tank, stop delivering SbCl5 to the SbCl5 temporary storage tank; (3.2) When the R22 reactor reaches the overflow level and begins to overflow into the SbCl5 temporary storage tank, the AHF delivery rate is adjusted to the CHCl3 delivery rate (the mol ratio of AHF to CHCl3 is 2:1); (3.3) Adjust the R22 reactor temperature, R21 reflux tower temperature and pressure, catalyst reactor temperature, HF reflux tower temperature and pressure to the process setting range; (3.5) When the temperature, pressure, liquid level of the R22 reaction system, the temperature, pressure, liquid level of the catalyst reactor, and the flow rates of AHF, CHCl3, and Cl2 reach the set values, the system starts to run continuously.

[0009] Furthermore, preferably, in the step (3.2), the delivery amount is: the mol ratio of CHCl3 to AHF is 1:2.

[0010] Further, preferably: R22 reactor and SbCl5 temporary storage tank operating conditions: Operating pressure 0.8~1.7MPa, preferably 1.0~1.5MPa; The operating temperature is 60~120℃, preferably 60~70℃.

[0011] Furthermore, preferably: the operating conditions of the catalyst reactor and the catalyst temporary storage tank are: Operating pressure 0.1~1.0MPa, preferably 0.3~0.5MPa; Operating temperature 30~80℃, preferably 50~60℃; The weight content of SbCl5 in the catalyst is 0-20%, preferably 5-15%.

[0012] The present invention also provides a device for producing difluoromonochloromethane by a staged process, comprising: SbCl5 temporary storage tank, catalyst reactor, HF recovery tower, catalyst temporary storage tank, catalyst pump, static mixer, R22 reactor and R21 reflux tower; The overflow port of the SbCl5 temporary storage tank is communicated with the catalyst reactor, the overflow port of the catalyst reactor is communicated with the catalyst temporary storage tank, the catalyst reactor is communicated with the HF recovery tower, the bottom of the HF recovery tower is communicated with the catalyst reactor, the catalyst temporary storage tank is communicated with the static mixer through a catalyst pump, the catalyst temporary storage tank is communicated with the HF recovery tower, the static mixer is communicated with the R22 reactor, the overflow port of the R22 reactor is communicated with the SbCl5 temporary storage tank, the R22 reactor is communicated with the R21 reflux tower, and the SbCl5 temporary storage tank is communicated with the R21 reflux tower.

[0013] Beneficial effects of the present invention: 1. The present invention adopts a staged reaction to separate the catalyst generation reaction and the chloroform fluorination reaction, thereby avoiding the step of deacidification treatment of organic matter carrying HF and HCl, and avoiding the large-flow material circulation carrying organic matter during HCl treatment, which can greatly reduce the equipment specifications; The present invention separates the escape of HCl and R22, avoids the large-flow gas escape in the original production method, greatly reduces the amount of high-boiling substances carried by the gas escape, and greatly reduces the cooling load of the reflux tower.

[0014] 2. Reduce the residence time of organic matter in the reaction system, reduce the occurrence of side reactions (R23), and reduce production material consumption; 3. The present invention separates inorganic acid and organic matter, thus avoiding the repeated process of washing and drying the organic matter in the original production method; 4. The present invention separates inorganic acid and organic matter, avoiding the problem of the outlet of waste hydrofluoric acid produced as a by-product in the original production method and reducing the environmental pressure of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 It is a schematic diagram of the structure of the device of the present invention; In the figure, 1-static mixer, 2-R22 reactor, 3-R21 reflux tower, 4-SbCl5 temporary storage tank, 5-catalyst reactor, 6-HF recovery tower, 7-catalyst pump, 8-catalyst temporary storage tank. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] Example 1 like Figure 1 As shown, a device for producing difluoromonochloromethane by a staged process comprises: a SbCl5 temporary storage tank 4, a catalyst reactor 5, an HF recovery tower 6, a catalyst temporary storage tank 8, a catalyst pump 7, a static mixer 1, an R22 reactor 2 and an R21 reflux tower 3; The overflow port of the SbCl5 temporary storage tank 4 is communicated with the catalyst reactor 5, the overflow port of the catalyst reactor 5 is communicated with the catalyst temporary storage tank 8, the catalyst reactor 5 is communicated with the HF recovery tower 6, the bottom of the HF recovery tower 6 is connected to the catalyst reactor 5, the catalyst temporary storage tank 8 is communicated with the static mixer 1 through the catalyst pump 7, the catalyst temporary storage tank 8 is communicated with the HF recovery tower 6, the static mixer 1 is communicated with the R22 reactor 2, the overflow port of the R22 reactor 2 is communicated with the SbCl5 temporary storage tank 4, the R22 reactor 2 is communicated with the R21 reflux tower 3, and the SbCl5 temporary storage tank 4 is communicated with the R21 reflux tower 3.

[0019] Example 2 A method for producing monochlorodifluoromethane by a staged process comprises the following steps: (1) Catalyst reaction: (1.1) Antimony pentachloride is pumped into the SbCl5 temporary storage tank 4. When the liquid level reaches a certain level, SbCl5 begins to overflow into the catalyst reactor 5; (1.2) When SbCl5 begins to overflow into the catalyst reactor 5, the HF reflux tower is turned on; (1.3) When the SbCl5 liquid level is higher than the outlet of the AHF feeding pipe, start the AHF delivery pump and add AHF according to the molar amount of SbCl5. When the liquid level of the catalyst reactor reaches the overflow position and the liquid level of the catalyst temporary storage tank 8 reaches the specified position, start pumping the catalyst to the R22 reactor 2; (1.4) The catalyst overflowing into the catalyst temporary storage tank 8 carries trace amounts of HF and HCl, which escape from the temporary storage tank and are introduced into the HF reflux tower for fractionation. HF refluxes into the catalyst reactor 5 to continue to participate in the reaction; (1.5) When the catalyst begins to overflow into the catalyst temporary storage tank 8, a small amount of chlorine gas is continuously introduced into the bottom of the catalyst reactor 5 to ensure that a small amount of SbCl3 in SbCl5 is converted into SbCl5; (1.6) The HCl generated by the reaction carries a small amount of HF, which is fractionated in the HF reflux tower. The HF returns to the catalyst reactor to continue the reaction, and the HCl is sent to the HCl absorption system to produce a hydrochloric acid solution of a certain concentration.

[0020] (2) Fluorination reaction: (2.1) When the catalyst begins to be pumped into the R22 reactor 2, start the R21 reflux tower 3 and start the R22 reactor 2 heating system; (2.2) When the liquid level of R22 reactor 2 reaches 50%, chloroform is pumped into R22 reactor 2. Chloroform and catalyst are mixed in static mixer 1 and then enter R22 reactor 2 to start chloroform fluorination reaction. R22 generated by the reaction carries a small amount of R21 and CHCl3. In R21 reflux tower 3, R21 and CHCl3 are refluxed into R22 reactor 2 after fractionation to continue the reaction. (2.3) The R22 gas discharged from the top of the R21 reflux tower 3 is introduced into the R22 refining system (the R22 refining system in the original system) to produce R22 products and recover unreacted R21; (2.4) The SbCl5 that overflows into the SbCl5 temporary storage tank 4 carries trace amounts of R21 and CHCl3, escapes from the temporary storage tank and is introduced into the R21 reflux tower 3 for fractionation, and then returns to the R22 reactor 2 to continue the reaction.

[0021] (3) Continuous operation of the reaction: (3.1) When the R22 reactor reaches the overflow level and begins to overflow into the SbCl5 temporary storage tank 4, stop delivering SbCl5 to the SbCl5 temporary storage tank 4; (3.2) When the R22 reactor reaches the overflow level and begins to overflow into the SbCl5 temporary storage tank 4, the AHF delivery rate is adjusted to the delivery rate of CHCl3, and the molar ratio of CHCl3 to AHF is 1:2.

[0022] (3.3) Adjust the temperature of R22 reactor, the temperature and pressure of R21 reflux tower 3, the temperature of catalyst reactor 5, and the temperature and pressure of HF reflux tower to the process setting range; (3.5) When the temperature, pressure, liquid level of the R22 reaction system, the temperature, pressure, liquid level of the catalyst reactor 5, and the flow rates of AHF, CHCl3, and Cl2 reach the set values, the system starts to run continuously.

[0023] In the present invention, the catalyst reaction and the chloroform fluorination reaction are separated, and the catalyst concentration is reduced, so the reaction pressure can be appropriately reduced and the reaction temperature can be appropriately increased. When the catalyst concentration is kept below 100% (the content of SbCl5 in the catalyst is greater than 0%, but not too high, because if it is too high, the circulation volume is large, which also affects the production capacity of the equipment), the production capacity of the equipment will be increased by increasing the reaction temperature, but the side reactions will also increase; increasing the reaction pressure has little effect on the production capacity, but will increase the occurrence of side reactions.

[0024] Operating conditions of R22 reactor and SbCl5 temporary storage tank 4: Operating pressure 0.8~1.7MPa, preferably 1.0~1.5MPa; The operating temperature is 60~120℃, preferably 60~70℃.

[0025] Operating conditions of catalyst reactor and catalyst temporary storage tank 8: Operating pressure 0.1~1.0MPa, preferably 0.3~0.5MPa; Operating temperature 30~80℃, preferably 50~60℃; In the present invention, the catalyst concentration is kept below 100%, that is, the content of SbCl5 in the catalyst is greater than 0%, but not too high. If it is too high, the circulation volume will be large, which will affect the production capacity of the equipment. The weight content of SbCl5 in the catalyst is 0-20%, preferably 5-15%. In the present invention, the SbCl5 content in the catalyst is 5%.

[0026] Comparative Example 1 One-pot process for producing difluorochloromethane. The specific process is shown in the background technology section. The specific process parameters are shown in Table 1.

[0027] Table 1 Comparison of consumption and by-product indicators of the "one-pot method" reaction process and the reaction process of the present invention (tons of R22 product) .

[0028] As can be seen from the above table, the method of the present invention not only effectively reduces the raw material consumption, especially the process water consumption, which is reduced by 26.98% compared with the one-pot method, but also reduces the non-condensable gas emission by 38.33%. There is no waste fluorine acid emission in the production process, which effectively reduces the environmental pressure.

[0029] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for producing difluorochloromethane by a staged process, characterized in that: The following steps are involved: (1) Catalyst reaction: SbCl5 is introduced into the SbCl5 temporary storage tank. When the liquid in the SbCl5 temporary storage tank reaches a certain liquid level, it overflows into the catalyst reactor. AHF is added to generate catalyst SbCl4F and HCl in the catalyst reactor. When the liquid level of the catalyst reactor reaches the overflow position, the catalyst overflows into the catalyst temporary storage tank. The trace HF and HCl in the catalyst temporary storage tank are recycled. When the liquid level of the catalyst temporary storage tank reaches a specified position, the catalyst is pumped to the R22 reactor; (2) Fluorination reaction: The catalyst and chloroform begin to carry out chloroform fluorination reaction in the R22 reactor, and the generated reaction gas enters the R21 reflux tower, and CHClF2 and CHCl3 are refluxed into the R22 reactor after fractionation to continue to participate in the reaction, and the CHClF2 gas is introduced into the subsequent refining system for refining to obtain a CHClF2 product, and another part overflows into the SbCl5 temporary storage tank, and trace amounts of CHCl3 and CHCl2F in the SbCl5 temporary storage tank are introduced into the R21 reflux tower for fractionation; (3) Continuous operation of the reaction: When material from the R22 reactor overflows into the SbCl5 temporary storage tank, the introduction of SbCl5 is stopped, the AHF delivery rate is adjusted to the delivery rate of CHCl3, the R22 reactor temperature, the R21 reflux tower temperature and pressure, the catalyst reactor temperature, and the HF reflux tower temperature and pressure are adjusted to the process setting range, and the system starts to run continuously.

2. The method for producing difluorochloromethane by a staged process according to claim 1, characterized in that: The step (1) is specifically as follows: (1.1) Antimony pentachloride is pumped into the SbCl5 temporary storage tank. When the liquid level reaches a certain level, SbCl5 begins to overflow into the catalyst reactor; (1.2) When SbCl5 begins to overflow into the catalyst reactor, open the HF reflux tower; (1.3) When the SbCl5 liquid level is higher than the outlet of the AHF feeding pipe, start the AHF delivery pump and add AHF according to the molar amount of SbCl5. When the liquid level of the catalyst reactor reaches the overflow position and the liquid level of the catalyst temporary storage tank reaches the specified position, start pumping the catalyst to the R22 reactor; (1.4) The catalyst overflowing into the catalyst temporary storage tank carries trace amounts of HF and HCl, which escape from the temporary storage tank and are introduced into the HF reflux tower for fractionation. HF refluxes into the catalyst reactor to continue participating in the reaction; (1.5) When the catalyst begins to overflow into the catalyst temporary storage tank, start to continuously introduce a small amount of chlorine gas into the bottom of the catalyst reactor to ensure that the trace amount of SbCl3 in SbCl5 is converted into SbCl5; (1.6) The HCl generated by the reaction carries a small amount of HF, which is fractionated in the HF reflux tower. The HF returns to the catalyst reactor to continue the reaction, and the HCl is sent to the HCl absorption system to produce a hydrochloric acid solution of a certain concentration.

3. The method for producing difluorochloromethane by a staged process according to claim 1, characterized in that: The step (2) is specifically as follows: (2.1) When the catalyst begins to be pumped into the R22 reactor, start the R21 reflux tower and the R22 reactor heating system; (2.2) When the liquid level of the R22 reactor reaches 50%, chloroform is pumped into the R22 reactor to start the chloroform fluorination reaction. The R22 generated by the reaction carries a small amount of R21 and CHCl3. In the R21 reflux tower, R21 and CHCl3 are refluxed into the R22 reactor after fractionation and continue to participate in the reaction; (2.3) The R22 gas discharged from the top of the R21 reflux tower is introduced into the R22 refining system to produce R22 products and recover unreacted R21; (2.4) The SbCl5 that overflows into the SbCl5 temporary storage tank carries trace amounts of R21 and CHCl3, escapes from the temporary storage tank and is introduced into the R21 reflux tower for fractionation, and then returns to the R22 reactor to continue the reaction.

4. The method for producing chlorodifluoromethane by a staged process according to claim 1, characterized in that: The step (3) is specifically as follows: (3.1) When the R22 reactor reaches the overflow level and begins to overflow into the SbCl5 temporary storage tank, stop delivering SbCl5 to the SbCl5 temporary storage tank; (3.2) When the R22 reactor reaches the overflow level and begins to overflow into the SbCl5 temporary storage tank, adjust the AHF delivery rate to the CHCl3 delivery rate; (3.3) Adjust the R22 reactor temperature, R21 reflux tower temperature and pressure, catalyst reactor temperature, HF reflux tower temperature and pressure to the process setting range; (3.5) When the temperature, pressure, liquid level of the R22 reaction system, the temperature, pressure, liquid level of the catalyst reactor, and the flow rates of AHF, CHCl3, and Cl2 reach the set values, the system starts to run continuously.

5. The method for producing chlorodifluoromethane by a staged process according to claim 4, characterized in that: In the step (3.2), the delivery amount is: the molar ratio of CHCl3 to AHF is 1:

2.

6. A method for producing chlorodifluoromethane by a staged process according to any one of claims 1 to 5, characterized in that: Operating conditions of R22 reactor and SbCl5 temporary storage tank: Operating pressure 0.8~1.7MPa; Operating temperature 60~120℃; The operating conditions of the catalyst reactor and catalyst temporary storage tank are: Operating pressure 0.1~1.0MPa; Operating temperature 30~80℃; SbCl5 weight content in the catalyst: 0~20%.

7. The method for producing chlorodifluoromethane by a staged process according to claim 6, characterized in that: Operating conditions of R22 reactor and SbCl5 temporary storage tank: Operating pressure 1.0~1.5MPa; Operating temperature 60~70℃; The operating conditions of the catalyst reactor and catalyst temporary storage tank are: Operating pressure 0.3~0.5MPa; Operating temperature 50~60℃; SbCl5 weight content in the catalyst: 5~15%.

8. A device for producing difluoromonochloromethane by a staged process, characterized in that: include: SbCl5 temporary storage tank, catalyst reactor, HF recovery tower, catalyst temporary storage tank, catalyst pump, static mixer, R22 reactor and R21 reflux tower; The overflow port of the SbCl5 temporary storage tank is communicated with the catalyst reactor, the overflow port of the catalyst reactor is communicated with the catalyst temporary storage tank, the catalyst reactor is communicated with the HF recovery tower, the bottom of the HF recovery tower is communicated with the catalyst reactor, the catalyst temporary storage tank is communicated with the static mixer through a catalyst pump, the catalyst temporary storage tank is communicated with the HF recovery tower, the static mixer is communicated with the R22 reactor, the overflow port of the R22 reactor is communicated with the SbCl5 temporary storage tank, the R22 reactor is communicated with the R21 reflux tower, and the SbCl5 temporary storage tank is communicated with the R21 reflux tower.

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