Trifluorochloroethane and process for its preparation

Abstract

The application provides a trifluoro-monochloroethane and a preparation method thereof. The preparation method comprises the following steps: S100, preparing a catalyst comprising a porous chromium-based material; S200, placing the catalyst obtained in S100 into a tubular reactor, and introducing gaseous dichlorodifluoroethane and hydrogen fluoride into the tubular reactor, and reacting under the conditions of a temperature of 250 DEG C to 300 DEG C and a pressure of 0.2 MPa to 0.6 MPa for more than 20 h to obtain a crude trifluoro-monochloroethane; and S300, refining the crude trifluoro-monochloroethane obtained in S200 to obtain a fine trifluoro-monochloroethane. The trifluoro-monochloroethane preparation method provided by the application has the advantages of low cost, simple process, continuous feeding and suitability for large-scale production.

Description

Technical Field

[0001] This invention relates to the technical field of chemical processes, and more specifically, to a trifluorochloroethane and its preparation method. Background Technology

[0002] 2-Chloro-1,1,1-trifluoroethane (R133a), or trifluorochloroethane for short, is a fluorinated intermediate with broad application prospects in many fields such as refrigeration, foam production, and fire-fighting equipment manufacturing. For example, trifluorochloroethane can be used to prepare HFC-134a refrigerant in air conditioning products, and also to prepare chemicals such as trifluoroethanol.

[0003] The existing technology (such as Chinese patent CN112441873B) describes a method for preparing trifluorochloroethane using difluorodichloroethane and hydrogen fluoride as raw materials. In this reaction process, a solid-phase chromium catalyst with high catalytic activity, which has undergone fluorination treatment, is generally selected.

[0004] The shortcoming of the existing technology is that the specific surface area of ​​solid chromium catalysts is limited, and they cannot fully contact the gaseous reaction raw materials, which leads to less than ideal catalytic efficiency and effect. Summary of the Invention

[0005] The problem addressed by this invention is how to provide a solid-phase chromium catalyst with a large specific surface area that can fully contact the gaseous reactants, thereby improving the catalytic efficiency and effect in the preparation of trifluorochloroethane and reducing the reaction cost.

[0006] To address the above problems, this invention provides a method for preparing trifluorochloroethane, the method comprising:

[0007] S100, a catalyst for preparing porous chromium-based materials;

[0008] S200: The catalyst obtained in S100 is placed in a tubular reactor, and gaseous dichlorodifluoroethane and hydrogen fluoride are introduced into the tubular reactor. The reaction is carried out for more than 20 hours under temperature conditions of 250℃ to 300℃ and pressure conditions of 0.2MPa to 0.6MPa to obtain crude trifluorochloroethane.

[0009] S300 is used to refine the crude trifluorochloroethane obtained from S200 to obtain refined trifluorochloroethane.

[0010] In any of the above technical solutions, in S200, the molar ratio of dichlorodifluoroethane to hydrogen fluoride is dichlorodifluoroethane:hydrogen fluoride = 1:(8-12).

[0011] In any of the above technical solutions, in S300, the refining process sequentially includes: removal of hydrogen chloride, phase separation, water washing, and alkali washing.

[0012] In any of the above technical solutions, in S300, after alkaline washing, the refining process sequentially includes: water removal, removal of light components, and distillation.

[0013] In any of the above technical solutions, S100 specifically includes:

[0014] S110. The activated carbon is subjected to acid washing, alkali washing and activation treatment in sequence to obtain modified activated carbon.

[0015] S120: A precursor is prepared using raw materials including modified activated carbon obtained from S110 and chromium trichloride.

[0016] S130: The precursor is subjected to calcination and fluorination treatment in sequence to obtain the catalyst.

[0017] In any of the above technical solutions, S110 specifically includes:

[0018] S111. After acid washing, the activated carbon is placed in hydrochloric acid and stirred to obtain the first acid-washed activated carbon.

[0019] S112. The first acid-washed activated carbon obtained in S111 is placed in hydrofluoric acid, stirred to perform acid washing treatment again, then taken out and washed with water to obtain the second acid-washed activated carbon.

[0020] S113. Place the second acid-washed activated carbon obtained in S112 into ammonia water, stir to carry out alkaline washing treatment, and then take it out to obtain alkaline-washed activated carbon.

[0021] S114. The alkaline-washed activated carbon obtained in S113 is soaked in a 6wt% to 8wt% sodium alginate aqueous solution for 2h to 2.5h, then removed and dried to obtain modified activated carbon.

[0022] In any of the above technical solutions, in S111, the mass ratio of activated carbon to hydrochloric acid is activated carbon:hydrochloric acid aqueous solution = (40-50):100, and the concentration of hydrochloric acid is 36%.

[0023] In any of the above technical solutions, in S112, the mass ratio of the first acid-washed activated carbon to hydrofluoric acid is first acid-washed activated carbon: hydrofluoric acid = (30-40): 100.

[0024] In any of the above technical solutions, in S113, the mass ratio of the second acid-washed activated carbon to ammonia water is second acid-washed activated carbon: ammonia water = (30-40): 100.

[0025] In any of the above technical solutions, S120 specifically includes:

[0026] S121. According to the mass ratio of chitosan: nickel dichloride: cerium trichloride: chromium trichloride: anhydrous ethanol = (6-8): (4-6): (4-6): (10-20): 100, first weigh chitosan and dissolve it fully in 5% to 10% hydrochloric acid, then add nickel dichloride, cerium trichloride, chromium trichloride and anhydrous ethanol and continue to mix evenly to obtain the first mixture;

[0027] S122. Weigh the modified activated carbon obtained in S110 according to the mass ratio of modified activated carbon: chromium trichloride = (20-25): (10-20). Mix the modified activated carbon and the first mixture obtained in S121 evenly and let it stand for 12h to 18h at a temperature of 50℃ to 60℃ to obtain the second mixture.

[0028] S123. The second mixture is fed into the reactor, heated and pressurized to a temperature of 240°C to 250°C and a pressure of 7.5MPa to 8.5MPa, kept at the temperature and pressure for 2 to 2.5 hours, then depressurized and cooled, filtered, to obtain solids.

[0029] S124. Fill the solid material into the mold and press it into a block-shaped precursor.

[0030] In any of the above technical solutions, S130 specifically includes:

[0031] S131. The precursor is fed into a muffle furnace and calcined at a temperature of 300°C to 350°C for 4 to 6 hours.

[0032] S132. The precursor is fed into a tubular reactor and gaseous hydrogen fluoride is introduced. Fluorination is carried out at a temperature of 300°C to 350°C for 6 to 8 hours to obtain the catalyst.

[0033] The present invention also provides a trifluorochloroethane, which is obtained by the preparation method of any of the above technical solutions.

[0034] Beneficial effects

[0035] This invention provides a method for preparing trifluorochloroethane. The method first prepares a porous chromium-based catalyst. Then, the catalyst is placed in a tubular reactor, and gaseous dichlorodifluoroethane and hydrogen fluoride are introduced into the reactor. The reaction is carried out at a temperature of 250°C to 300°C and a pressure of 0.2 MPa to 0.6 MPa for more than 20 hours to obtain crude trifluorochloroethane. Finally, the crude trifluorochloroethane is purified to obtain refined trifluorochloroethane. This invention uses a special process to prepare a porous chromium-based material as a catalyst. The chromium-based catalyst components are uniformly distributed in the porous support material. Utilizing its porous structure and large specific surface area, it promotes full contact between the catalytically active components and the gaseous reactants, thereby improving the catalytic efficiency and effect of the reaction. This results in a low-cost, simple, continuously feedable, and large-scale trifluorochloroethane preparation process. Detailed Implementation

[0036] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, a detailed description of specific embodiments of the present invention will be provided below.

[0037] Unless otherwise specified, all reagents and raw materials used in this invention are commercially available. Experimental methods in the following examples that do not specify particular conditions should be performed according to conventional methods and conditions, or as selected in the product instructions.

[0038] This invention provides a method for preparing trifluorochloroethane, the method comprising:

[0039] S100, a catalyst for preparing porous chromium-based materials;

[0040] S200: The catalyst obtained in S100 is placed in a tubular reactor, and gaseous dichlorodifluoroethane and hydrogen fluoride are introduced into the tubular reactor. The reaction is carried out for more than 20 hours under temperature conditions of 250℃ to 300℃ and pressure conditions of 0.2MPa to 0.6MPa to obtain crude trifluorochloroethane.

[0041] S300 is used to refine the crude trifluorochloroethane obtained from S200 to obtain refined trifluorochloroethane.

[0042] Specifically, the dichlorodifluoroethane in this embodiment of the invention is 1,2-dichloro-1,1-difluoroethane (R132b), and the trifluorochloroethane in this embodiment of the invention is 2-chloro-1,1,1-trifluoroethane (R133a).

[0043] The reaction formula of this invention is as follows: CF2Cl-CH2Cl+HF→F3C-CH2Cl+HCl. To ensure the smooth progress of the above reaction, in S200, the molar ratio of dichlorodifluoroethane to hydrogen fluoride is dichlorodifluoroethane:hydrogen fluoride = 1:(8-12). Preferably, in S200, the molar ratio of dichlorodifluoroethane to hydrogen fluoride is dichlorodifluoroethane:hydrogen fluoride = 1:10.

[0044] It is understandable that after obtaining crude trifluorochloroethane, it needs to be purified to obtain refined trifluorochloroethane. Those skilled in the art can select and adjust the specific technical means for purifying trifluorochloroethane according to their actual needs and conventional experimental capabilities. For example, in S300, the purification process sequentially includes: removal of hydrogen chloride, phase separation, water washing, and alkaline washing. For example, in S300, after alkaline washing, the purification process sequentially includes: dehydration, removal of light components, and distillation.

[0045] To improve reaction efficiency, this invention uses a porous chromium-based material prepared from S100 as a catalyst in the above reaction. S100 specifically includes:

[0046] S110. The activated carbon is subjected to acid washing, alkali washing and activation treatment in sequence to obtain modified activated carbon.

[0047] S120: A precursor is prepared using raw materials including modified activated carbon obtained from S110 and chromium trichloride.

[0048] S130: The precursor is subjected to calcination and fluorination treatment in sequence to obtain the catalyst.

[0049] One of the purposes of using S110 to sequentially perform acid washing, alkali washing, and activation treatment on activated carbon is to remove impurities such as sulfur, phosphorus, and nitrogen from the activated carbon. To achieve this purpose, S110 specifically includes:

[0050] S111. After acid washing, the activated carbon is placed in hydrochloric acid and stirred to obtain the first acid-washed activated carbon.

[0051] S112. The first acid-washed activated carbon obtained in S111 is placed in hydrofluoric acid, stirred to perform acid washing treatment again, then taken out and washed with water to obtain the second acid-washed activated carbon.

[0052] S113. Place the second acid-washed activated carbon obtained in S112 into ammonia water, stir to carry out alkaline washing treatment, and then take it out to obtain alkaline-washed activated carbon.

[0053] S114. The alkaline-washed activated carbon obtained in S113 is soaked in a 6wt% to 8wt% sodium alginate aqueous solution for 2h to 2.5h, then removed and dried to obtain modified activated carbon.

[0054] Preferably, in S111, the mass ratio of activated carbon to hydrochloric acid is activated carbon:hydrochloric acid aqueous solution = (40-50):100, and the concentration of hydrochloric acid is 36%.

[0055] More preferably, in S111, the mass ratio of activated carbon to hydrochloric acid is activated carbon:hydrochloric acid aqueous solution = 45:100.

[0056] Preferably, in S112, the mass ratio of the first pickled activated carbon to hydrofluoric acid is first pickled activated carbon: hydrofluoric acid = (30-40): 100.

[0057] More preferably, in S112, the mass ratio of the first acid-washed activated carbon to hydrofluoric acid is 35:100.

[0058] Preferably, in S113, the mass ratio of the second acid-washed activated carbon to ammonia is second acid-washed activated carbon: ammonia = (30-40): 100.

[0059] More preferably, in S113, the mass ratio of the second acid-washed activated carbon to ammonia water is 35:100.

[0060] Preferably, in S111, the temperature of the hydrochloric acid is 36°C to 40°C, and the stirring time for pickling is 1 hour to 1.5 hours.

[0061] Preferably, in S112, the volume concentration of hydrofluoric acid is 25% and the temperature is 25°C to 30°C, and the stirring time for re-acid washing is 0.5h to 1h.

[0062] Preferably, in S113, the ammonia water has a mass concentration of 26% and a temperature of 25°C to 30°C, and the time for stirring to carry out alkaline washing treatment is 1 hour to 1.5 hours.

[0063] The purpose of preparing the precursor using S120 is to load the chromium catalyst onto an activated carbon support, and then solidify the chromium catalyst onto the activated carbon support through calcination treatment in S130. Activated carbon is a porous material, and the uniformity of the chromium catalyst dispersion within the pores of the porous material has a crucial impact on the catalyst's catalytic efficiency and effect. Therefore, this invention promotes the uniform dispersion of the chromium catalyst within the pores of the porous material through the following steps S121 to S124. S120 specifically includes:

[0064] S121. According to the mass ratio of chitosan: nickel dichloride: cerium trichloride: chromium trichloride: anhydrous ethanol = (6-8): (4-6): (4-6): (10-20): 100, first weigh chitosan and dissolve it fully in 5% to 10% hydrochloric acid, then add nickel dichloride, cerium trichloride, chromium trichloride and anhydrous ethanol and continue to mix evenly to obtain the first mixture;

[0065] S122. Weigh the modified activated carbon obtained in S110 according to the mass ratio of modified activated carbon: chromium trichloride = (20-25): (10-20). Mix the modified activated carbon and the first mixture obtained in S121 evenly and let it stand for 12h to 18h at a temperature of 50℃ to 60℃ to obtain the second mixture.

[0066] S123. The second mixture is fed into the reactor, heated and pressurized to a temperature of 240°C to 250°C and a pressure of 7.5MPa to 8.5MPa, kept at the temperature and pressure for 2 to 2.5 hours, then depressurized and cooled, filtered, to obtain solids.

[0067] S124. Fill the solid material into the mold and press it into a block-shaped precursor.

[0068] Chromium trichloride is used as the functional component of the catalyst, and nickel dichloride and cerium trichloride are used in combination with chromium trichloride to improve its catalytic effect. The reason for using the above steps is that chitosan carries a positive charge; treating the functional component of the catalyst with chitosan can promote its uniform distribution in activated carbon treated with negatively charged sodium alginate. Chitosan has poor solubility in ethanol.

[0069] Therefore, the mixture was first dissolved in hydrochloric acid, and then nickel dichloride, cerium trichloride, chromium trichloride, and anhydrous ethanol were added and mixed thoroughly. Next, the first mixture containing chitosan and chromium trichloride was mixed thoroughly with modified activated carbon and allowed to stand and age under heating conditions to obtain a second mixture. Finally, the second mixture was subjected to heat and pressure treatment in a reaction vessel. Under temperature conditions of 240°C to 250°C and pressure conditions of 7.5 MPa to 8.5 MPa, the ethanol in the second mixture reached a supercritical state. This invention utilizes the interfacial characteristics of supercritical ethanol to ensure that sodium alginate, chitosan, and functional catalytic components, as organic matter, are uniformly distributed on the surface and in the pores of the modified activated carbon within the supercritical ethanol.

[0070] One of the purposes of using S130 is to increase the strength of the precursor, which is pressed into a block shape, and solidify its structure through calcination. Furthermore, the temperature conditions of 300°C to 350°C allow sodium alginate and chitosan to carbonize. In particular, the relatively large amount of chitosan can form new carbonized pores in the modified activated carbon, increase the specific surface area of ​​the modified activated carbon, and promote full contact between the catalytic components and the gaseous reaction raw materials, thereby improving the catalytic efficiency and effect of the reaction.

[0071] Example 1

[0072] This embodiment provides a porous chromium-based catalyst, which is prepared as follows:

[0073] S1. According to the mass ratio of activated carbon to hydrochloric acid aqueous solution = 45:100, the activated carbon is placed in hydrochloric acid with a concentration of 36% and a temperature of 40°C and stirred for 1 hour to perform acid washing treatment. After that, it is taken out and washed with water to obtain the first acid-washed activated carbon.

[0074] S2. According to the mass ratio of first acid-washed activated carbon to hydrofluoric acid = 35:100, the first acid-washed activated carbon is placed in hydrofluoric acid with a volume concentration of 25% and a temperature of 30°C, stirred for 1 hour to perform acid washing again, then taken out and washed with water to obtain the second acid-washed activated carbon.

[0075] S3. According to the mass ratio of second acid-washed activated carbon to ammonia water = 35:100, the second acid-washed activated carbon is placed in ammonia water with a concentration of 26% and a temperature of 30°C, stirred for 1.5 hours to carry out alkaline washing treatment, and then taken out to obtain alkaline-washed activated carbon.

[0076] S4. Soak the alkaline-washed activated carbon in an 8 wt% sodium alginate aqueous solution for 2.5 h, then remove and dry to obtain modified activated carbon.

[0077] S5. According to the mass ratio of chitosan: nickel dichloride: cerium trichloride: chromium trichloride: anhydrous ethanol = 8:4:4:15:100, first weigh chitosan and dissolve it fully in 10% hydrochloric acid, then add nickel dichloride, cerium trichloride, chromium trichloride and anhydrous ethanol and continue to mix evenly to obtain the first mixture.

[0078] S6. Weigh the modified activated carbon according to the mass ratio of modified activated carbon to chromium trichloride = 20:15. Mix the modified activated carbon and the first mixture evenly and let it stand at 55°C for 12 hours to obtain the second mixture.

[0079] S7. The second mixture is fed into the reactor, heated and pressurized to a temperature of 247°C and a pressure of 7.5 MPa, kept at the temperature and pressure for 2 hours, then depressurized and cooled, filtered, and the solids are obtained.

[0080] S8. Fill the solid material into the mold and press it into a block-shaped precursor.

[0081] S9. The precursor is fed into a muffle furnace and calcined at 350°C for 5 hours.

[0082] S10. The precursor is fed into a tubular reactor and gaseous hydrogen fluoride is introduced. Fluorination is carried out at 300°C for 6 hours to obtain the catalyst.

[0083] The activated carbon used was coconut shell activated carbon purchased from Shandong Nanke Company. Testing showed that the specific surface area of ​​the catalyst prepared in Example 1 was 1280 m². 2 / g.

[0084] Example 2

[0085] This embodiment provides a porous chromium-based catalyst, which is prepared as follows:

[0086] S1. According to the mass ratio of activated carbon to hydrochloric acid aqueous solution = 45:100, the activated carbon is placed in hydrochloric acid with a concentration of 36% and a temperature of 40°C and stirred for 1 hour to perform acid washing treatment. After that, it is taken out and washed with water to obtain the first acid-washed activated carbon.

[0087] S2. According to the mass ratio of first acid-washed activated carbon to hydrofluoric acid = 35:100, the first acid-washed activated carbon is placed in hydrofluoric acid with a volume concentration of 25% and a temperature of 30°C, stirred for 1 hour to perform acid washing again, then taken out and washed with water to obtain the second acid-washed activated carbon.

[0088] S3. According to the mass ratio of second acid-washed activated carbon to ammonia water = 35:100, the second acid-washed activated carbon is placed in ammonia water with a concentration of 26% and a temperature of 30°C, stirred for 1.5 hours to carry out alkaline washing treatment, and then taken out to obtain alkaline-washed activated carbon.

[0089] S4. Wash the alkaline activated carbon in deionized water, remove it and dry it to obtain modified activated carbon.

[0090] S5. Chromium trichloride and anhydrous ethanol are mixed evenly according to a mass ratio of 20:100 to obtain the first mixture.

[0091] S6. Weigh the modified activated carbon according to the mass ratio of modified activated carbon to chromium trichloride = 20:15. Mix the modified activated carbon and the first mixture evenly and let it stand at 55°C for 12 hours to obtain the second mixture.

[0092] S7. The second mixture is fed into the reactor, heated and pressurized to a temperature of 247°C and a pressure of 7.5 MPa, kept at the temperature and pressure for 2 hours, then depressurized and cooled, filtered, and the solids are obtained.

[0093] S8. Fill the solid material into the mold and press it into a block-shaped precursor.

[0094] S9. The precursor is fed into a muffle furnace and calcined at 350°C for 5 hours.

[0095] S10. The precursor is fed into a tubular reactor and gaseous hydrogen fluoride is introduced. Fluorination is carried out at 300°C for 6 hours to obtain the catalyst.

[0096] The specific surface area of ​​the catalyst prepared in Example 2 was found to be 1090 m². 2 / g.

[0097] Example 3

[0098] This embodiment provides a method for preparing trifluorochloroethane, as follows: The catalyst obtained in Example 1 is placed in a tubular reactor, and gaseous dichlorodifluoroethane and hydrogen fluoride are introduced into the reactor. The reaction is carried out at 290°C and 0.2 MPa for 24 hours to obtain crude trifluorochloroethane. Gas chromatography analysis shows that the content of trifluorochloroethane in the gas phase after the reaction is 93.8%.

[0099] Example 4

[0100] This embodiment provides a trifluorochloroethane, prepared in the same manner as in Example 3, except that the reaction time is 30 hours. Gas chromatography analysis revealed that the content of trifluorochloroethane in the gas phase after the reaction was 94.1%.

[0101] Example 5

[0102] This embodiment provides a trifluorochloroethane, prepared in the same manner as in Example 3, except that an equal weight of the catalyst obtained in Example 2 is used. Gas chromatography analysis revealed that the trifluorochloroethane content in the gas phase after the reaction was 90.5%.

[0103] Example 6

[0104] This embodiment provides a trifluorochloroethane, prepared in the same manner as in Example 3, except that it uses the same weight of catalyst obtained in Example 1. However, this catalyst underwent accelerated testing before use. The accelerated testing was performed as follows: the catalyst obtained in Example 1 was placed in a reaction vessel, and a mixture of ethanol and water vapor at 200°C was introduced at a 1:1 mass ratio. The mixture was then held at 1 MPa for 100 hours. Gas chromatography analysis showed that the trifluorochloroethane content in the gas phase after the reaction was 93.3%.

[0105] Example 7

[0106] This embodiment provides a trifluorochloroethane, prepared in the same manner as in Example 3, except that it uses the same weight of catalyst obtained in Example 1. However, this catalyst underwent accelerated testing before use. The accelerated testing was performed as follows: the catalyst obtained in Example 1 was placed in a reaction vessel, and a mixture of ethanol and water vapor at 200°C was introduced at a 1:1 mass ratio. The mixture was then held at 1 MPa for 200 hours. Gas chromatography analysis showed that the trifluorochloroethane content in the gas phase after the reaction was 93.2%.

[0107] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for preparing trifluorochloroethane, characterized in that, The preparation method includes: S100, a catalyst for preparing porous chromium-based materials; S200: The catalyst obtained in S100 is placed in a tubular reactor, and gaseous dichlorodifluoroethane and hydrogen fluoride are introduced into the tubular reactor. The reaction is carried out for more than 20 hours under temperature conditions of 250°C to 300°C and pressure conditions of 0.2MPa to 0.6MPa to obtain crude trifluorochloroethane. S300: The crude trifluorochloroethane obtained in S200 is purified to obtain refined trifluorochloroethane. S100 specifically includes: S110. The activated carbon is subjected to acid washing, alkali washing and activation treatment in sequence to obtain modified activated carbon. S121. According to the mass ratio of chitosan: nickel dichloride: cerium trichloride: chromium trichloride: anhydrous ethanol = (6-8): (4-6): (4-6): (10-20): 100, first weigh the chitosan and dissolve it fully in 5% to 10% hydrochloric acid, then add the nickel dichloride, the cerium trichloride, the chromium trichloride and the anhydrous ethanol and continue to mix evenly to obtain the first mixture; S122. Weigh the modified activated carbon obtained in S110 according to the mass ratio of modified activated carbon: chromium trichloride = (20-25): (10-20). Mix the modified activated carbon and the first mixture obtained in S121 evenly and let it stand at a temperature of 50°C to 60°C for 12h to 18h to obtain the second mixture. S123. The second mixture is fed into a reactor, heated and pressurized to a temperature of 240°C to 250°C and a pressure of 7.5MPa to 8.5MPa, kept at the temperature and pressure for 2 to 2.5 hours, then depressurized and cooled, filtered, to obtain solids. S124. The solid material is filled into a mold and pressed into a block-shaped precursor. S130. The precursor is subjected to calcination and fluorination treatment in sequence to obtain the catalyst.

2. The preparation method according to claim 1, characterized in that, In S200, the molar ratio of dichlorodifluoroethane to hydrogen fluoride is dichlorodifluoroethane:hydrogen fluoride = 1:(8-12).

3. The preparation method according to claim 1, characterized in that, In S300, the refining process sequentially includes: removal of hydrogen chloride, phase separation, water washing, and alkali washing.

4. The preparation method according to claim 3, characterized in that, In S300, after the alkaline washing, the refining process further includes: water removal, removal of light components, and distillation.

5. The preparation method according to claim 1, characterized in that, S110 specifically includes: S111. The activated carbon is placed in hydrochloric acid and stirred to perform the acid washing treatment, then taken out and washed with water to obtain the first acid-washed activated carbon. S112. The first acid-washed activated carbon obtained in S111 is placed in hydrofluoric acid, stirred to perform the acid washing treatment again, then taken out and washed with water to obtain the second acid-washed activated carbon. S113. Place the second acid-washed activated carbon obtained in S112 into ammonia water, stir to carry out the alkaline washing treatment, and then take it out to obtain alkaline-washed activated carbon. S114. The alkaline-washed activated carbon obtained in S113 is soaked in a 6wt% to 8wt% sodium alginate aqueous solution for 2h to 2.5h, then removed and dried to obtain the modified activated carbon.

6. The preparation method according to claim 5, characterized in that, In S111, the mass ratio of activated carbon to hydrochloric acid is activated carbon:hydrochloric acid aqueous solution = (40-50):100, and the concentration of hydrochloric acid is 36%. In S112, the mass ratio of the first acid-washed activated carbon to the hydrofluoric acid is first acid-washed activated carbon: hydrofluoric acid = (30-40): 100; In S113, the mass ratio of the second acid-washed activated carbon to the ammonia water is second acid-washed activated carbon: ammonia water = (30-40):

100.

7. The preparation method according to claim 1, characterized in that, S130 specifically includes: S131. The precursor is fed into a muffle furnace and calcined at a temperature of 300°C to 350°C for 4 to 6 hours. S132. The precursor is fed into a tubular reactor and gaseous hydrogen fluoride is introduced. The fluorination treatment is carried out at a temperature of 300°C to 350°C for 6 to 8 hours to obtain the catalyst.