A preparation method of dichlorooctafluorobutane

Abstract

The present invention relates to the technical field of dichlorooctafluorobutane, specifically a preparation method of dichlorooctafluorobutane, comprising the following specific steps: S1: preparation of monohydrogen nickel potassium dichloride: its preparation method comprises the following steps: A: potassium chloride is dissolved in deionized water to obtain a potassium chloride solution, and the weight percentage concentration is 20 30%; B: nickel chloride is dissolved in deionized water to obtain a nickel chloride solution, and the weight percentage concentration is 50 80%; C: the nickel chloride solution obtained by B is added dropwise to the potassium chloride solution obtained by A, and potassium nickel trichloride solution is prepared by reaction. The present invention is low in raw material cost. 1,1,2-tetrafluoroethane reacts with catalyst monohydrogen nickel potassium dichloride under ultraviolet light to generate dichlorooctafluorobutane, so that the cost of making dichlorooctafluorobutane is low, the yield is high, and the waste content is small, it is easy to realize industrialization, and the application process of hexafluorobutadiene replacing traditional electronic etching agent carbon tetrafluoride can be effectively accelerated.

Description

Technical Field

[0001] The invention relates to the technical field of dichlorooctafluorobutane, in particular to a method for preparing dichlorooctafluorobutane. Background Art

[0002] Dichlorooctafluorobutane is a chemical substance with the chemical formula C₄Cl₂F₄ and a molecular weight of 270.94. It has a density of 1.719 g / mL, a melting point of -68°C, a boiling point of 63°C, and a refractive index of 1.313. Dichlorooctafluorobutane can be produced with a purity of up to 99% and exhibits high chemical stability. Dichlorooctafluorobutane is a basic raw material for the preparation of hexafluorobutadiene, hexafluorobutyne, and other materials. Hexafluorobutadiene is a new, environmentally friendly electronic etchant with excellent etching precision.

[0003] At present, the invention patent publication number CN113527033A discloses a method for preparing dichlorooctafluorobutane by photochlorination; the method for preparing dichlorooctafluorobutane by photochlorination of the invention promotes the reaction speed of the photochlorination process, reduces the progress of side reactions, and reduces the phenomenon that is difficult to separate by distillation due to the similar structure of by-product impurities. The high-purity product 2,3-dichlorooctafluorobutane can be obtained after further distillation and purification. At the same time, the reactant perfluorobutene itself is a solvent, and no additional solvent needs to be added, which significantly reduces the cost. However, the above method is to obtain the target product by reacting 2-perfluorobutene with chlorine, wherein the raw material cost is very expensive, the yield is low, there is a lot of waste, and the atom economy is not good. At the same time, the high cost restricts the application process of replacing traditional electronic etching agent carbon tetrafluoride with hexafluorobutadiene in my country. For this reason, we propose a method for preparing dichlorooctafluorobutane. Summary of the Invention

[0004] The object of the present invention is to provide a method for preparing dichlorooctafluorobutane, which has the advantages of low raw material cost, high yield and less waste, and solves the disadvantages of high raw material cost, low yield, large amount of waste and poor atom economy. At the same time, the high cost has restricted the application of hexafluorobutadiene to replace the traditional electronic etching agent carbon tetrafluoride in my country.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for preparing dichlorooctafluorobutane, wherein 1,1,1,2-tetrafluoroethane reacts with a catalyst of potassium dichloronickel hydrogen in a tubular reactor under ultraviolet light to produce dichlorooctafluorobutane, and the reaction equation is as follows:

[0006] 2CF3CH2F + 4Cl2 + KNiHCl2 ----- CF3CFCl-CFClCF3 + KNiCl3 + 5HCl

[0007] The catalyst can be reused by a hydrogenation activation method. The catalyst activation method is that the catalyst is activated under the action of hydrogen. The activation equation is:

[0008] KNiCl3+H2-----KNiHCl2+HCl

[0009] The method for preparing dichlorooctafluorobutane comprises the following specific steps:

[0010] S1: Preparation of potassium nickel monohydrogen dichloride: The preparation method comprises the following steps:

[0011] A: Dissolve potassium chloride in deionized water to obtain a potassium chloride solution with a weight percentage concentration of 20-30%;

[0012] B: dissolving nickel chloride in deionized water to obtain a nickel chloride solution with a concentration of 50-80% by weight;

[0013] C: The nickel chloride solution obtained in B is added dropwise to the potassium chloride solution obtained in A to react and prepare a nickel potassium chloride solution, and the nickel potassium chloride solution is evaporated to obtain nickel potassium chloride;

[0014] D: directly hydrogenate the potassium nickel trichloride obtained in C with hydrogen to obtain potassium nickel monohydrogen dichloride;

[0015] S2: 17-27 kg of potassium nickel dichloride (nickel monohydrogenate) was loaded into six 40x6000 transparent quartz tubular reactors, with the catalyst potassium nickel dichloride filling volume being 27-34 liters, and the reactor temperature was raised to 180-250°C;

[0016] S3: N2 is introduced at a rate of 8-13 L / min to further dry the catalyst. After 4-6.5 hours, the temperature is raised to 230-270°C. Preheated 1,1,1,2-tetrafluoroethane is introduced from the upper part of the tubular reactor, and chlorine is introduced from the lower part of the tubular reactor.

[0017] S4: removing the reaction material from the bottom of the tubular reactor, washing it directly with water, drying it with molecular sieves, condensing it, collecting it by rectification, and sampling and analyzing it to obtain dichlorooctafluorobutane;

[0018] S5: When the conversion rate and yield of 1,1,1,2-tetrafluoroethane decrease, stop feeding and switch to hydrogen feeding. Maintain the temperature of the tubular reactor at 350-420°C, the hydrogen feeding rate at 340-380 L / min under standard conditions, and the pressure of the tubular reactor at 0.9 MPa. After 25-30 minutes, activation is completed.

[0019] S6: Prepare to switch the feeding. The feeding rate of 1,1,1,2-tetrafluoroethane is 170-190 liters / min under standard conditions, and the feeding rate of chlorine is 340-380 liters / min under standard conditions. Maintain the pressure of the tubular reactor at 0.08 MPa. The reaction materials are removed from the bottom of the tubular reactor, directly washed with water alkali, dried with molecular sieves, condensed, distilled, collected and sampled to obtain dichlorooctafluorobutane.

[0020] Preferably, the catalytic reaction temperature in the catalytic reaction equation is 150-250° C., the reaction pressure is 0.01-0.1 MPa, and the residence time is 10-20 seconds.

[0021] Preferably, the activation reaction temperature in the activation equation is 350-450° C., the reaction pressure is 0.1-0.8 MPa, and the residence time is 10-20 seconds.

[0022] Preferably, the ultraviolet light source in the catalytic reaction is a 110V 275W ultraviolet lamp source.

[0023] Preferably, the reaction temperature for preparing the potassium nickel trichloride solution in step S1 C is 50-80° C., the pressure is normal pressure, and the reaction time is 5-8 hours.

[0024] Preferably, in step S1 D, the molar ratio of potassium nickel trichloride to hydrogen is 1:1-1.2, the hydrogenation temperature is 350-450° C., the reaction pressure is 0.1-1 MPa, and the residence time is 10-20 seconds.

[0025] Preferably, the jacket of the quartz transparent tubular reactor in step S2 is heated by thermal oil.

[0026] Preferably, the feeding rate of 1,1,1,2-tetrafluoroethane in step S3 is 170-190 liters / min under standard conditions, the feeding rate of chlorine is 340-380 liters / min under standard conditions, and the pressure of the tubular reactor is maintained at 0.08 MPa.

[0027] Preferably, the molecular sieve drying temperature in step S4 is 200-350° C., and the drying time is 2-3.5 hours.

[0028] Preferably, the condensation temperature in step S4 is 62-63°C.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The present invention can generate dichlorooctafluorobutane by reacting 1,1,2-tetrafluoroethane, a low-cost raw material, with a catalyst of potassium dichloronickel under ultraviolet light. This reduces the cost of producing dichlorooctafluorobutane, increases the yield, and reduces the waste content. It is easy to industrialize the process and can effectively accelerate the application of hexafluorobutadiene in replacing carbon tetrafluoride, a traditional electronic etching agent.

[0031] 2. The catalyst of the present invention can be reused by a hydrogenation activation method, which ensures the production efficiency of the product while facilitating its use by people and can reduce the waste of resources and the preparation cost of dichlorooctafluorobutane. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic diagram of the method steps of Comparative Example 1 of the present invention;

[0033] Figure 2 Schematic diagram of the method steps of Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0034] Example 1: In this example, dichlorooctafluorobutane is prepared by the following method, comprising the following steps:

[0035] S1: Preparation of potassium nickel monohydrogen dichloride: The preparation method comprises the following steps:

[0036] A: Dissolve potassium chloride in deionized water to obtain a potassium chloride solution with a weight percentage concentration of 20%;

[0037] B: dissolving nickel chloride in deionized water to obtain a nickel chloride solution having a weight percent concentration of 50%;

[0038] C: The nickel chloride solution obtained in B is added dropwise to the potassium chloride solution obtained in A to react and prepare a nickel potassium chloride solution. The reaction temperature of the nickel potassium chloride solution is 50°C, the pressure is normal pressure, and the reaction time is 5 hours. The nickel potassium chloride solution is evaporated to obtain nickel potassium chloride;

[0039] D: The potassium nickel trichloride obtained in C is directly subjected to hydrogenation reaction with hydrogen. The molar ratio of potassium nickel trichloride to hydrogen is 1:1, the hydrogenation temperature is 350°C, the reaction pressure is 0.1 MPa, and the residence time is 10 seconds to obtain potassium nickel dichloride monohydrogenate.

[0040] S2: 17 kg of potassium nickel monochloride (NiCl2) was loaded into six 40x6000 transparent quartz tubular reactors. The jacket of the transparent quartz tubular reactor was heated with thermal oil. The volume of the catalyst potassium nickel monochloride (NiCl2) was 27 L. The reactor was heated to 180°C. The ultraviolet light source for the catalytic reaction was a 110 V 275 W UV lamp.

[0041] S3: N2 was introduced at a rate of 8 L / min to further dry the catalyst. After 4 hours, the temperature was raised to 230°C. 1,1,1,2-tetrafluoroethane was preheated and introduced from the upper part of the tubular reactor at a feed rate of 170 L / min under standard conditions. Chlorine was introduced from the lower part of the tubular reactor at a feed rate of 340 L / min under standard conditions. The pressure of the tubular reactor was maintained at 0.08 MPa.

[0042] S4: The reaction material was removed from the bottom of the tubular reactor, washed directly with water, dried over molecular sieves, condensed, rectified, collected, and sampled for analysis. After 1 hour, dichlorooctafluorobutane with a purity of 99% was collected, the conversion rate of 1,1,1,2-tetrafluoroethane was 95.3%, and the yield was 90.4%;

[0043] S5: When the conversion rate and yield of 1,1,1,2-tetrafluoroethane decrease, stop feeding and switch to hydrogen feeding. Maintain the temperature of the tubular reactor at 350°C, the hydrogen feeding rate at standard conditions at 340 L / min, and the pressure of the tubular reactor at 0.9 MPa. After 25 minutes, activation is completed.

[0044] S6: Prepare to switch the feeding, the feeding rate of 1,1,1,2-tetrafluoroethane is 170 liters / min under standard conditions, the feeding rate of chlorine is 340 liters / min under standard conditions, and the pressure of the tubular reactor is maintained at 0.08 MPa. The reaction materials are removed from the bottom of the tubular reactor, directly washed with water alkali, dried with molecular sieves, condensed, distilled, collected and sampled. After 1 hour, dichlorooctafluorobutane with a purity of 99% is collected, the conversion rate of 1,1,1,2-tetrafluoroethane is 95.1%, and the yield is 90.2%.

[0045] It should be noted that the preparation principle of the method for preparing dichlorooctafluorobutane from third-generation refrigeration-grade tetrafluoroethane is: CF3CFH2 undergoes a catalytic chlorination coupling reaction with a catalyst by light to obtain CF3CFCl-CFClCF3, and the coupling agent used is KNiHCl2.

[0046] Example 2: In this example, dichlorooctafluorobutane is prepared by the following method, comprising the following steps:

[0047] S1: Preparation of potassium nickel monohydrogen dichloride: The preparation method comprises the following steps:

[0048] A: Dissolve potassium chloride in deionized water to obtain a potassium chloride solution with a weight percentage concentration of 30%;

[0049] B: dissolving nickel chloride in deionized water to obtain a nickel chloride solution having a concentration of 80% by weight;

[0050] C: adding the nickel chloride solution obtained in B dropwise to the potassium chloride solution obtained in A to react and prepare a nickel potassium chloride solution. The reaction temperature of the nickel potassium chloride solution is 80°C, the pressure is normal pressure, and the reaction time is 8 hours. The nickel potassium chloride solution is evaporated to obtain nickel potassium chloride.

[0051] D: The potassium nickel trichloride obtained in C is directly subjected to hydrogenation reaction with hydrogen. The molar ratio of potassium nickel trichloride to hydrogen is 1:1.2, the hydrogenation temperature is 450°C, the reaction pressure is 1 MPa, and the residence time is 20 seconds to obtain potassium nickel monohydrogen dichloride.

[0052] S2: 6 40x6000 transparent quartz tubular reactors were filled with 27 kg of potassium nickel dichloride monohydrogenate. The jacket of the transparent quartz tubular reactor was heated with thermal oil. The volume of the catalyst potassium nickel dichloride monohydrogenate was 34 L. The reactor was heated to 250°C. The ultraviolet light source for the catalytic reaction was a 110 V 275 W ultraviolet lamp.

[0053] S3: N2 was introduced at a rate of 8 L / min to further dry the catalyst. After 6.5 hours, the temperature was raised to 270°C. 1,1,1,2-tetrafluoroethane was preheated and introduced from the upper part of the tubular reactor at a feed rate of 190 L / min under standard conditions. Chlorine was introduced from the lower part of the tubular reactor at a feed rate of 380 L / min under standard conditions. The pressure of the tubular reactor was maintained at 0.08 MPa.

[0054] S4: The reaction material was removed from the bottom of the tubular reactor, washed directly with water, dried over molecular sieves, condensed, rectified, collected, and sampled for analysis. After 1 hour, dichlorooctafluorobutane with a purity of 99% was collected, the conversion rate of 1,1,1,2-tetrafluoroethane was 94.5%, and the yield was 90.4%;

[0055] S5: When the conversion rate and yield of 1,1,1,2-tetrafluoroethane decrease, stop feeding and switch to hydrogen feeding. Maintain the temperature of the tubular reactor at 420°C, the hydrogen feeding rate at standard conditions at 380 L / min, and the pressure of the tubular reactor at 0.9 MPa. After 30 minutes, activation is completed.

[0056] S6: Prepare to switch the feeding, the feeding rate of 1,1,1,2-tetrafluoroethane is 190 liters / min under standard conditions, the feeding rate of chlorine is 380 liters / min under standard conditions, and the pressure of the tubular reactor is maintained at 0.08 MPa. The reaction materials are removed from the bottom of the tubular reactor, directly washed with water alkali, dried with molecular sieves, condensed, distilled, collected and sampled. After 1 hour, dichlorooctafluorobutane with a purity of 99% is collected, the conversion rate of 1,1,1,2-tetrafluoroethane is 94.4%, and the yield is 90.2%.

[0057] Example 3: In this example, dichlorooctafluorobutane is prepared by the following method, comprising the following steps:

[0058] S1: Preparation of potassium nickel monohydrogen dichloride: The preparation method comprises the following steps:

[0059] A: Dissolve potassium chloride in deionized water to obtain a potassium chloride solution with a weight percentage concentration of 25%;

[0060] B: dissolving nickel chloride in deionized water to obtain a nickel chloride solution having a weight percent concentration of 65%;

[0061] C: The nickel chloride solution obtained in B is added dropwise to the potassium chloride solution obtained in A to react and prepare a nickel potassium chloride solution. The reaction temperature of the nickel potassium chloride solution is 65°C, the pressure is normal pressure, and the reaction time is 6.5 hours. The nickel potassium chloride solution is evaporated to obtain nickel potassium chloride;

[0062] D: The potassium nickel trichloride obtained in C is directly subjected to hydrogenation reaction with hydrogen at a molar ratio of 1:1.1, a hydrogenation temperature of 400°C, a reaction pressure of 0.5 MPa, and a residence time of 15 seconds to obtain potassium nickel dichloride monohydrogenate;

[0063] S2: 27 kg of potassium nickel monochloride (NiCl2) was loaded into six 40x6000 transparent quartz tubular reactors. The jacket of the transparent quartz tubular reactor was heated with thermal oil. The volume of the catalyst potassium nickel monochloride (NiCl2) was 31 L. The reactor was heated to 215°C. The ultraviolet light source for the catalytic reaction was a 110 V 275 W UV lamp.

[0064] S3: N2 was introduced at a rate of 8 L / min to further dry the catalyst. After 5 hours, the temperature was raised to 255°C. 1,1,1,2-tetrafluoroethane was preheated and introduced from the upper part of the tubular reactor at a feed rate of 180 L / min under standard conditions. Chlorine was introduced from the lower part of the tubular reactor at a feed rate of 360 L / min under standard conditions. The pressure of the tubular reactor was maintained at 0.08 MPa.

[0065] S4: The reaction material was removed from the bottom of the tubular reactor, washed directly with water, dried over molecular sieves, condensed, rectified, collected, and sampled for analysis. After 1 hour, dichlorooctafluorobutane with a purity of 99% was collected, the conversion rate of 1,1,1,2-tetrafluoroethane was 96%, and the yield was 92%;

[0066] S5: When the conversion rate and yield of 1,1,1,2-tetrafluoroethane decrease, stop feeding and switch to hydrogen feeding. Maintain the temperature of the tubular reactor at 380°C, the hydrogen feeding rate at standard conditions at 360 L / min, and the pressure of the tubular reactor at 0.9 MPa. After 28 minutes, activation is completed.

[0067] S6: Prepare to switch the feeding, the feeding rate of 1,1,1,2-tetrafluoroethane is 180 liters / min under standard conditions, the feeding rate of chlorine is 360 liters / min under standard conditions, and the pressure of the tubular reactor is maintained at 0.08 MPa. The reaction materials are removed from the bottom of the tubular reactor, directly washed with water alkali, dried with molecular sieves, condensed, distilled, collected and sampled. After 1 hour, dichlorooctafluorobutane with a purity of 99% is collected, the conversion rate of 1,1,1,2-tetrafluoroethane is 95.8%, and the yield is 91.9%.

[0068] Comparative Example 1, compared with Example 1, dichlorooctafluorobutane was prepared by reacting 2-perfluorobutene with chlorine.

[0069] The preparation method comprises the following contents:

[0070] Perfluorobutene and chlorine are introduced into a reactor with a molar ratio of chlorine to perfluorobutene of 1-5:1. A photochlorination reaction is carried out under a light environment. The reaction temperature is -20-100°C, the reaction pressure is 10-800kPa, and the reaction residence time is 10-100s. After the reaction is completed, the material is discharged, and the product 2,3-dichlorooctafluorobutane is obtained after alkali washing, drying, and distillation purification.

[0071] Comparative Example 2, compared with Example 1, according to the literature Chemistry letters (1991)(10), 1825-6 describes a method for preparing dichlorooctafluorobutane, using dichlorotetrafluoroethane as a raw material to react and prepare dichlorooctafluorobutane.

[0072] For application performance verification, the products prepared in Examples 1 to 3 of the present invention and the products prepared in Comparative Examples 1 to 2 were subjected to gas chromatography to detect the content of the finished products. The measured yields and selectivities of dichlorooctafluorobutane are shown in Table 1.

[0073] Table 1 is the yield and selectivity analysis of dichlorooctafluorobutane prepared in Examples 1-3 and Comparative Examples 1-2

[0074] Dichlorooctafluorobutane yield / % Dichlorooctafluorobutane selectivity / % Example 1 99.1 99.2 Example 2 99 99.1 Example 3 98.9 99.02 Comparative Example 1 98.6 98.2 Comparative Example 2 89.01 90.21

[0075] As can be seen from Table 1, the dichlorooctafluorobutane prepared in Examples 1 to 3 has excellent yield and selectivity compared with the dichlorooctafluorobutane prepared in Comparative Examples 1 and 2.

[0076] The waste content and product cost of the products prepared in Examples 1 to 3 of the present invention were compared with those of the products prepared in Comparative Examples 1 to 2, and the waste content and product cost of the products were divided into ten stages from low to high. The first to ten stages were replaced by scores of 1 to 10, where scores of 1 to 3 were low, 4 to 6 were average, 7 to 8 were high, and 9 to 10 were very high. The measured waste content and product cost of dichlorooctafluorobutane are shown in Table 2.

[0077] Table 2 is an analysis of the content and total cost of dichlorooctafluorobutane prepared in Examples 1-3 and Comparative Examples 1-2.

[0078] Waste content Product Cost Example 1 1 1 Example 2 1 1 Example 3 1 1 Comparative Example 1 1 7 Comparative Example 2 2 4

[0079] As can be seen from Table 2, the waste content and product cost of the dichlorooctafluorobutane prepared in Examples 1-3 are lower than those of the products prepared in Comparative Examples 1-2.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing dichlorooctafluorobutane, characterized in that: In a tubular reactor, 1,1,1,2-tetrafluoroethane reacts with the catalyst potassium dichloronickel hydrogen under ultraviolet light to produce dichlorooctafluorobutane. The reaction equation is as follows: 2CF3CH2F + 3Cl2 + KNiHCl2 ----- CF3CFCl-CFClCF3 + KNiCl3 + 3HCl + H2 The catalyst can be reused by a hydrogenation activation method. The catalyst activation method is that the catalyst is activated under the action of hydrogen. The activation equation is: KNiCl3+H2-----KNiHCl2+HCl The method for preparing dichlorooctafluorobutane comprises the following specific steps: S1: Preparation of potassium nickel monohydrogen dichloride: The preparation method comprises the following steps: A: Dissolve potassium chloride in deionized water to obtain a potassium chloride solution with a weight percentage concentration of 20-30%; B: dissolving nickel chloride in deionized water to obtain a nickel chloride solution with a concentration of 50-80% by weight; C: The nickel chloride solution obtained in B is added dropwise to the potassium chloride solution obtained in A to react and prepare a nickel potassium chloride solution, and the nickel potassium chloride solution is evaporated to obtain nickel potassium chloride; D: directly hydrogenate the potassium nickel trichloride obtained in C with hydrogen to obtain potassium nickel monohydrogen dichloride; S2: 17-27 kg of potassium nickel dichloride (nickel monohydrogenate) was loaded into six 40x6000 transparent quartz tubular reactors, with the catalyst potassium nickel dichloride filling volume being 27-34 liters, and the reactor temperature was raised to 180-250°C; S3: N2 is introduced at a rate of 8-13 L / min to further dry the catalyst. After 4-6.5 hours, the temperature is raised to 230-270°C. Preheated 1,1,1,2-tetrafluoroethane is introduced from the upper part of the tubular reactor, and chlorine is introduced from the lower part of the tubular reactor. S4: removing the reaction material from the bottom of the tubular reactor, washing it directly with water, drying it with molecular sieves, condensing it, collecting it by rectification, and sampling and analyzing it to obtain dichlorooctafluorobutane; S5: When the conversion rate and yield of 1,1,1,2-tetrafluoroethane decrease, stop feeding and switch to hydrogen feeding. Maintain the temperature of the tubular reactor at 350-420°C, the hydrogen feeding rate at 340-380 L / min under standard conditions, and the pressure of the tubular reactor at 0.9 MPa. After 25-30 minutes, activation is completed. S6: Prepare to switch the feeding. The feeding rate of 1,1,1,2-tetrafluoroethane is 170-190 liters / min under standard conditions, and the feeding rate of chlorine is 340-380 liters / min under standard conditions. Maintain the pressure of the tubular reactor at 0.08 MPa. The reaction materials are removed from the bottom of the tubular reactor, directly washed with water alkali, dried with molecular sieves, condensed, distilled, collected and sampled to obtain dichlorooctafluorobutane.

2. The method for preparing dichlorooctafluorobutane according to claim 1, wherein: The catalytic reaction temperature in the catalytic reaction equation is 150-250° C., the reaction pressure is 0.01-0.1 MPa, and the residence time is 10-20 seconds.

3. The method for preparing dichlorooctafluorobutane according to claim 1, wherein: The activation reaction temperature in the activation equation is 350-450° C., the reaction pressure is 0.1-0.8 MPa, and the residence time is 10-20 seconds.

4. The method for preparing dichlorooctafluorobutane according to claim 1, wherein: The ultraviolet light source in the catalytic reaction is a 110V 275W ultraviolet lamp source.

5. The method for preparing dichlorooctafluorobutane according to claim 1, wherein: The reaction temperature for preparing the potassium nickel trichloride solution in step S1 C is 50-80° C., the pressure is normal pressure, and the reaction time is 5-8 hours.

6. The method for preparing dichlorooctafluorobutane according to claim 1, wherein: In step S1 D, the molar ratio of potassium nickel trichloride to hydrogen is 1:1-1.2, the hydrogenation temperature is 350-450° C., the reaction pressure is 0.1-1 MPa, and the residence time is 10-20 seconds.

7. The method for preparing dichlorooctafluorobutane according to claim 1, wherein: The jacket of the quartz transparent tubular reactor in step S2 is heated by thermal oil.

8. The method for preparing dichlorooctafluorobutane according to claim 1, wherein: In step S3, the feeding rate of 1,1,1,2-tetrafluoroethane is 170-190 liters / min under standard conditions, the feeding rate of chlorine is 340-380 liters / min under standard conditions, and the pressure of the tubular reactor is maintained at 0.08 MPa.

9. The method for preparing dichlorooctafluorobutane according to claim 1, wherein: The molecular sieve drying temperature in step S4 is 200-350° C., and the drying time is 2-3.5 hours.

10. The method for preparing dichlorooctafluorobutane according to claim 1, wherein: The condensation temperature in step S4 is 62-63°C.

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