A gas-phase preparation method of 1,1,1,4,4,4-hexafluoro-2-butyne

Abstract

The present invention discloses a gas-phase preparation method of 1,1,1,4,4,4-hexafluoro-2-butyne. Using a mixture of 2,3-dichloro-1,1,1,4,4,4-hexafluoro-2-butene and hydrogen as raw materials, under the action of a particulate catalyst, 1,1,1,4,4,4-hexafluoro-2-butyne is obtained through a one-step hydrodechlorination reaction. The catalyst includes a carbon carrier and an active phase in the form of hollow spheres supported on the carbon carrier. The active phase includes: a first metal selected from at least one of silver, copper, nickel, and cobalt; and a second metal selected from at least one of palladium, platinum, and rhodium. The present invention has the advantages of high product selectivity, high catalytic activity, obtaining the reaction product through a one-step reaction, and being suitable for industrial application, etc.

Description

Technical Field

[0001] The present invention relates to the synthesis of fluorinated alkynes, and particularly to a preparation method of 1,1,1,4,4,4-hexafluoro-2-butyne and a preparation method of a catalyst for preparing 1,1,1,4,4,4-hexafluoro-2-butyne. Background Art

[0002] 1,1,1,4,4,4-Hexafluoro-2-butyne (HFB), CAS No. 692-50-2, molecular formula CF3C≡CCF3, freezing point -117 °C, boiling point -24.6 °C, molecular weight 162.033, is soluble in acetone, acetonitrile, dichloromethane, trichlorofluoromethane, toluene, pentane, etc. Hexafluoro-2-butyne can be widely used as a fluorinated intermediate, such as for synthesizing compounds containing bis(trifluoromethyl) blocks, as an important monomer of fluoropolymers, etc., and can also be used in the fields of fluorinated electronic gases and fire extinguishing agents.

[0003] Currently, the synthesis routes of HFB mainly include the following several kinds:

[0004] 1. Liquid-phase dehalogenation process

[0005] (1) Using hexachlorobutadiene as a raw material, under the action of a fluorination reagent, it is fluorinated to 2,3-dichlorohexafluoro-2-butene (CFO-1316), and then hexaf luoro-2-butyne is prepared by liquid-phase zinc powder dechlorination;

[0006] (2) Using 1,1,1-trifluorotrichloroethane as a raw material, first gas-phase coupling generates 2,3-dichlorohexafluoro-2-butene (CFO-1316), and then hexaf luoro-2-butyne is prepared by metal dechlorination;

[0007] (3) Using carbon tetrachloride and dichlorotrifluoropropene as raw materials, CuCl2 as a catalyst, and acetonitrile as a solvent for liquid-phase telomerization to obtain CF3CCl2CHClCCl3, and this product is obtained by liquid-phase fluorination (SbCl5 catalyst) or gas-phase fluorination (Cr2O3 / Al2O3 catalyst) to obtain hexafluorochlorobutane, and then hexaf luoro-2-butyne is synthesized by alkali solution dehydrochlorination and zinc powder dechlorination.

[0008] The above liquid-phase dehalogenation process has the disadvantages of low yield and long time consumption.

[0009] 2. Liquid-phase dehydrohalogenation process

[0010] (1) Using hexachlorobutadiene and potassium fluoride as raw materials, first synthesize heptafluorobutene, and then obtain hexaf luoro-2-butyne by dehydrofluorination through molecular sieve or butyllithium. However, this method has high fluorination temperature, prominent solid waste problems, long reaction time, and is only suitable for laboratory research and cannot be applied industrially.

[0011] (2) Using hexafluoropropene and chloroform as raw materials, first telomerize to obtain CCl3CF2CHFCF3, then subject it to liquid-phase fluorination under the catalysis of SbCl5 to obtain CF3CF2CHFCF3, and finally dehydrofluorinate using Ni-Cu-Cr as a catalyst to obtain hexafluoro-2-butyne. However, this method has a long reaction route, a large amount of three wastes, and high costs, which is not conducive to industrial application.

[0012] 3. Fe complex-catalyzed dehalogenation process

[0013] K.A. Thoreson et al. (Kristen A. Thoreson, Kristopher McNeill. Vicinal dichlorine elimination at dichloroalkenes promoted by a well-defined iron(0) complex[J]. Dalton Transactions, 2011, (40): 1646-1648. DOI: 10.1039 / c0dt01532f) found that under the action of an Fe complex (SiP3(dmpm)Fe), CFO-1316 can directly react to obtain hexafluoro-2-butyne, and the yield can reach 83%. However, the synthesis of this Fe complex is difficult, remaining at the research stage and unable to achieve industrial application.

[0014] 4. Gas-solid phase catalytic hydrogenation dechlorination process

[0015] Currently, in the process of preparing hexafluoro-2-butyne by hydrogenation dechlorination of CFO-1316, most are mentioned as by-products in the process of hydrogenation dechlorination of CFO-1316 to prepare HFO-1336.

[0016] Only the DuPont patent CN102264674B discloses a method for preparing hexafluoro-2-butyne by hydrogenation dechlorination of CFO-1316 under the catalysis of K-Cu-Ni / CaF2. The conversion rate of the raw material CFO-1316 is 38%, and the highest selectivity of hexafluoro-2-butyne is 80%. The rest of the by-products are 1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336) and 2-chloro-1,1,1,4,4,4-hexafluoro-2-butene (HCFO-1326). Although the selectivity of the reported catalyst reaches 80%, the conversion rate is only 38%, that is, the catalytic activity is low, and the raw material used is pure CFO-1316, and the tolerance of the catalyst to impurities in the raw material is not disclosed.

[0017] 2,3-Dichloro-1,1,1,4,4,4-hexafluoro-2-butene (CFO-1316), as a by-product in the production process of fluorochemical products, is highly toxic and belongs to the substances restricted in production and emission in China. It is difficult to treat, and currently it is mainly disposed of by incineration as hazardous waste.

[0018] If low-purity CFO-1316 can be directly resource-converted into 1,1,1,4,4,4-hexafluoro-2-butyne with high economic value without purification, it will not only solve the problem of by-product treatment but also improve the economic benefits of enterprises. At present, there is little research on the one-step gas-phase preparation process of HFB using CFO-1316 as the raw material, and there are many problems such as low catalyst activity, low product selectivity, and unclear catalyst stability, and it is even more impossible to directly convert the mixture containing CFO-1316 into high-value HFB. Summary of the Invention

[0019] In order to solve the above technical problems, the present invention provides a method for preparing 1,1,1,4,4,4-hexafluoro-2-butyne by one step, which has good catalytic activity, good anti-impurity interference performance, high selectivity, less amount of three wastes, and is suitable for industrial application.

[0020] The object of the present invention is achieved by the following technical solutions:

[0021] A gas-phase preparation method of 1,1,1,4,4,4-hexafluoro-2-butyne, using a mixture containing 2,3-dichloro-1,1,1,4,4,4-hexafluoro-2-butene and hydrogen as raw materials, and obtaining 1,1,1,4,4,4-hexafluoro-2-butyne through a one-step hydrodechlorination reaction under the action of a particulate catalyst; the catalyst includes a carbon carrier and an active phase in the form of a hollow sphere supported on the carbon carrier, and the active phase includes:

[0022] A first metal, the first metal is selected from at least one of silver, copper, nickel, and cobalt, preferably copper and nickel;

[0023] A second metal, the second metal is selected from at least one of palladium, platinum, and rhodium, preferably palladium and platinum.

[0024] In the present invention, the reduction potential of the first metal is lower than that of the second metal, which is conducive to the displacement reaction between the zero-valent first metal and the second metal ion solution, and is more conducive to the formation of the hollow spherical active phase.

[0025] In the catalyst of the present invention, the mass percentage content of the first metal is 0.2-10.0%, the mass percentage content of the second metal is 0.1-5.0%, and the rest is the carrier.

[0026] Preferably, in the catalyst, the mass percentage of the first metal is 0.2 - 6.0%, the mass percentage of the second metal is 0.5 - 2.0%, and the balance is the carrier.

[0027] The active phase in the catalyst of the present invention is a hollow structure, which is beneficial to the adsorption and diffusion of reactants and the desorption of products. At present, the active phases of hydrodechlorination catalysts are mostly non-hollow types. When reactants pass through the solid catalyst bed, they will diffuse from the catalyst surface into the catalyst interior. Since the interior of the catalyst active phase is a non-hollow structure, it takes a longer time for the reactants that enter the catalyst interior to react and the products to escape from the catalyst interior, increasing the residence time of the products and causing the products to be further hydrogenated to form by-products. The catalyst with a hollow structure is not only beneficial to the adsorption and diffusion of reactants, but also the products can easily escape after the reactants enter the catalyst interior for reaction, shortening the residence time of the products in the catalyst bed, and thus improving the selectivity of the products.

[0028] The excellent catalytic activity and high selectivity of the catalyst of the present invention enable it to tolerate the influence of other fluorochlorohydrocarbon impurities in the 2,3-dichloro-1,1,1,4,4,4-hexafluoro-2-butene mixture. When the mass percentage of 2,3-dichloro-1,1,1,4,4,4-hexafluoro-2-butene in the mixture is ≥60%, based on 2,3-dichloro-1,1,1,4,4,4-hexafluoro-2-butene, its raw material conversion rate and product selectivity are equivalent to those of the raw material conversion rate and product selectivity when 100% content of 2,3-dichloro-1,1,1,4,4,4-hexafluoro-2-butene is used as the raw material gas.

[0029] Therefore, the mass percentage of 2,3-dichloro-1,1,1,4,4,4-hexafluoro-2-butene in the 2,3-dichloro-1,1,1,4,4,4-hexafluoro-2-butene mixture of the present invention is ≥60%, preferably ≥70% by mass.

[0030] Furthermore, the 2,3-dichloro-1,1,1,4,4,4-hexafluoro-2-butene mixture includes at least one of 1,1,1-trichlorotrifluoroethane, 1,1-difluoro-1,2,2-trichloroethane, and 2,2-difluorotetrachloroethane.

[0031] In the process of one-step gas-phase preparation of 1,1,1,4,4,4-hexafluoro-2-butyne of the present invention, the molar ratio of 2,3-dichloro-1,1,1,4,4,4-hexafluoro-2-butene to hydrogen in the 2,3-dichloro-1,1,1,4,4,4-hexafluoro-2-butene mixture is 1:1.2 - 5, preferably 1:1.2 - 3.

[0032] The reaction temperature is 250 to 450 °C, the reaction pressure is atmospheric pressure to 1.0 MPa, and the raw material space velocity is 20 to 1500 h -1 Preferably, the reaction temperature is 250 to 380 °C, the reaction pressure is atmospheric pressure to 0.7 MPa, and the raw material space velocity is 120 to 1200 h -1 .

[0033] The present invention also provides a method for preparing a catalyst for preparing 1,1,1,4,4,4-hexafluoro-2-butyne. The catalyst is prepared by an electrochemical replacement method, which specifically includes the following steps:

[0034] A1. The impregnation, drying and reduction steps of the first metal soluble salt solution on the carbon support. The obtained carbon support loaded with the first metal is ultrasonically dispersed in water or ethylene glycol to form a slurry;

[0035] A2. While stirring, the soluble salt solution of the second metal is added dropwise to the slurry. After the addition is complete, the reaction continues for 2 to 3 hours;

[0036] A3. Filter, wash the filter cake with deoxygenated deionized water and ethanol until neutral and then dry to obtain the catalyst.

[0037] In step A1, the carbon support is activated carbon pretreated with a 2% to 70 wt% nitric acid solution or sodium hydroxide solution, which can clean the surface of the carbon support, remove metal oxides, and reduce the negative impact of these substances on the catalytic reaction, such as avoiding the formation of Fe2O3 to form Fe 3+ from affecting the catalyst. Preferably, the activated carbon is pretreated with a 5% to 30 wt% nitric acid solution or sodium hydroxide solution.

[0038] In step A1, the impregnation time is 2 to 5 hours. After impregnation, drying treatment is carried out, and the drying temperature is 90 to 120 °C; after drying, reduction is carried out in an atmosphere of a hydrogen-nitrogen mixed gas. The ratio of hydrogen to nitrogen in the hydrogen-nitrogen mixed gas is arbitrary. Preferably, the molar ratio of hydrogen to nitrogen is 3:1, the reduction temperature is 350 to 400 °C, and the reduction time is 2 h.

[0039] In step A2, magnetic stirring is started to keep the slurry in a stirred state. An appropriate amount of deoxygenated deionized water is added to the soluble salt solution of the second metal and then transferred to a dropping funnel, and the soluble salt solution of the second metal is added dropwise to the slurry. After the addition is complete, the system is sealed and stirring continues for 2 to 3 hours to ensure complete reaction.

[0040] In step A3, suction filtration is carried out. After washing the filter cake to neutral, it is placed in an oven at 90 to 120 °C and dried for 5 to 12 hours to obtain the catalyst.

[0041] The catalyst prepared by the present invention is used in gas-solid phase reactions, so a carbon carrier needs to be used to make the catalyst in particulate form. To match the reactor, it is preferred to screen the prepared catalyst to obtain catalysts with different mesh numbers to match reactors of different specifications.

[0042] The first metal soluble salt in the present invention is selected from the chloride, nitrate, sulfate or organic salt of the first metal, such as copper chloride, copper nitrate, copper sulfate, nickel chloride, nickel nitrate, nickel sulfate, nickel acetate, silver nitrate or silver acetate;

[0043] The second metal soluble salt in the present invention is selected from the chloride or nitrate of the second metal, such as the chloride or hydrochloride of palladium or platinum, ammonium chloroplatinate, the chloride (hydrated) or hydrochloride or nitrate or ammonium salt of rhodium.

[0044] Considering the availability of raw materials, the first metal soluble salt in the present invention is preferably the chloride or nitrate of copper or nickel, or the nitrate of silver, and other copper / nickel / silver-containing salts can also be used in the present invention.

[0045] The second metal soluble salt in the present invention is preferably the chloride or nitrate of palladium / platinum, the chloride (hydrated) or nitrate of rhodium, and other palladium / platinum / rhodium-containing salts can also be used in the present invention.

[0046] The catalyst of the present invention is prepared by an electrochemical replacement method, so that the atomic deposition of the second metal precursor occurs on the outer surface of the catalyst cluster, the atomic dissolution of the first metal occurs inside the catalyst cluster, and a hollow spherical active phase structure is formed by using the potential difference between the first metal and the second metal. As shown in the appendix Figure 1 The active phase formation process is as follows:

[0047] a) In redox, the surface atoms of the first metal tend to be oxidized on the crystal plane with the highest surface free energy (such as the {110} crystal plane), and the first metal is oxidized and dissolved into the solution after oxidation;

[0048] b) While the first metal (in the oxidized state) is dissolved into the solution, the electrons released by it are quickly transferred to the surface of the metal particles, and the electrons are captured by the second metal ions in the solution. The second metal ions are reduced on the outer surface of the first metal particles and deposited on the crystal plane with lower surface free energy (such as the {111} crystal plane);

[0049] c) As the first metal atoms are continuously oxidized and leave and the second metal ions are continuously reduced and deposited, voids are generated due to the position difference between oxidation and deposition;

[0050] d) The second metal particles deposited on the outer layer can effectively protect the first metal particles immediately below them from being oxidized, so the formed tiny voids will serve as the main sites for redox reactions.

[0051] With the continuous deposition and mass transfer of the second metal on the surface, at the end of the reaction, the voids gradually disappear and close, thus forming an active phase with a hollow structure.

[0052] The thickness of the outer layer of the active phase and the void size are related not only to the loading of the first metal but also to the stoichiometric ratio between the first metal and the second metal. For example, if the first metal is Ag and the second metal is Pt 4+ , for every 4 Ag atoms dissolved, 1 Pt 4+ ion is reduced, and a Pt-Ag shell layer with a thinner wall will be formed.

[0053] Compared with the prior art, the beneficial effects of the present invention include:

[0054] 1. The catalyst with a hollow active phase adopted in the present invention realizes the one-step preparation of hexafluoro-2-butyne from 2,3-dichloro-1,1,1,4,4,4-hexafluoro-2-butene, with a simple process, high product selectivity, and less three wastes.

[0055] 2. The highly active hollow active phase catalyst of the present invention can tolerate the influence of fluorochlorohydrocarbon impurities in the mixture containing 2,3-dichloro-1,1,1,4,4,4-hexafluoro-2-butene. The mixture can be directly converted into economically valuable products without rectification and purification, greatly reducing equipment investment, having good economic benefits, and having industrial application prospects. Description of the Drawings

[0056] Figure 1 is a schematic diagram of the formation process of the hollow active phase catalyst prepared by the electrochemical replacement method of the present invention; Figure 1 In it, the small balls represent the first metal, the large balls represent the second metal, and the gray represents the first metal or the second metal in the oxidized state.

[0057] Figure 2 is the TEM characterization diagram of the hollow active phase catalyst obtained in Example 3 of the present invention.

[0058] Figure 3 is the TEM characterization diagram of the non-hollow catalyst obtained in Comparative Example 1 of the present invention. Detailed Embodiments

[0059] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited to these specific embodiments. Those skilled in the art should recognize that the present invention covers all alternative solutions, improvement solutions, and equivalent solutions that may be included within the scope of the claims.

[0060] Example 1

[0061] S1. Weigh 3.0 g of Ni(NO3)2·6H2O and add 80.0 mL of distilled water to dilute it evenly. Then add 20 g of high-quality activated carbon carrier pretreated with 5% nitric acid, impregnate for more than 2 h, and then dry at 110 °C for 4 h. Perform temperature-raising reduction treatment under a hydrogen-nitrogen mixed gas (nitrogen: hydrogen = 3:1) atmosphere, with a reduction temperature of 400 °C and a reduction time of 2 h to obtain a carbon carrier loaded with Ni. Disperse the carbon carrier loaded with Ni in distilled water and ultrasonically disperse it to form a slurry;

[0062] S2. Add 80.0 mL of deoxygenated deionized water to 6.1 mL of hydrochloric acid solution of palladium chloride (concentration: 0.033 g Pd / mL), and transfer it to a pear-shaped funnel;

[0063] S3. Place the slurry of the carbon carrier loaded with Ni on a magnetic stirring table and stir at a certain rate. Drop the hydrochloric acid solution of palladium chloride in the pear-shaped funnel into the slurry; after dropping, seal the system and continue stirring for 3 h to complete the reaction;

[0064] S4. Perform suction filtration, wash the filter cake with deoxygenated deionized water and ethanol in sequence until it is neutral, and then place it in a vacuum drying oven and dry at 100 °C for 5 h to obtain the Pd-Ni / AC catalyst, denoted as Cat 1.

[0065] Example 2

[0066] S1. Weigh 1.57 g of AgNO3 and add 80.0 mL of distilled water to dilute it evenly. Then add 20 g of high-quality activated carbon carrier pretreated with 5% nitric acid, impregnate for more than 2 h, and then dry at 110 °C for 4 h. Perform temperature-raising reduction treatment under a hydrogen-nitrogen mixed gas (nitrogen: hydrogen = 3:1) atmosphere, with a reduction temperature of 350 °C and a reduction time of 2 h to obtain a carbon carrier loaded with Ag. Disperse the carbon carrier loaded with Ag in distilled water and ultrasonically disperse it to form a slurry;

[0067] The operations of S2 - S4 are the same as those in Example 1 to prepare the Pd-Ag / AC catalyst, denoted as Cat 2.

[0068] Example 3

[0069] S1. Weigh 1.5 g of Cu(NO3)2·3H2O and add 80.0 mL of distilled water to dilute it evenly. Then add 20 g of high-quality activated carbon carrier pretreated with 5% nitric acid, impregnate for more than 2 h, and then dry at 110 °C for 4 h. Perform temperature-raising reduction treatment under a hydrogen-nitrogen mixed gas (nitrogen: hydrogen = 3:1) atmosphere, with a reduction temperature of 350 °C and a reduction time of 2 h to obtain a carbon carrier loaded with Cu. Disperse the carbon carrier loaded with Cu in distilled water and ultrasonically disperse it to form a slurry;

[0070] S2. Add 80.0 mL of deoxygenated deionized water to 0.4 g of rhodium(III) chloride hydrate (Rh 38.5% - 42.5%), and transfer it to a pear-shaped funnel.

[0071] The operations of S3 - S4 are the same as those in Example 1 to prepare the Rh - Cu / AC catalyst, denoted as Cat 3.

[0072] Example 4

[0073] S1. Weigh 1.9 g of AgNO3 and add 80.0 mL of distilled water to dilute it evenly. Add 20 g of high-quality activated carbon support pretreated with 5% nitric acid, impregnate for more than 2 h, then dry at 110 °C for 4 h, and perform temperature-rising reduction treatment under a hydrogen-nitrogen mixed gas (nitrogen:hydrogen = 3:1) atmosphere. The reduction temperature is 350 °C and the reduction time is 2 h to obtain the carbon support loaded with Ni. Disperse the carbon support loaded with Ni in distilled water and perform ultrasonic dispersion to form a slurry.

[0074] S2. Add 80.0 mL of deoxygenated deionized water to 7.9 g of hydrochloric acid solution of platinum chloride (Pt 3.8%), and transfer it to a pear-shaped funnel.

[0075] The operations of S3 - S4 are the same as those in Example 1 to prepare the Pt - Ag / AC catalyst, denoted as Cat 4.

[0076] Example 5

[0077] S1. Weigh 0.6 g of Cu(NO3)2·3H2O and add 80.0 mL of distilled water to dilute it evenly. Add 20 g of high-quality activated carbon support pretreated with 5% nitric acid, impregnate for more than 2 h, then dry at 110 °C for 4 h, and perform temperature-rising reduction treatment under a hydrogen-nitrogen mixed gas (nitrogen:hydrogen = 3:1) atmosphere. The reduction temperature is 350 °C and the reduction time is 2 h to obtain the carbon support loaded with Cu. Disperse the carbon support loaded with Cu in distilled water and perform ultrasonic dispersion to form a slurry.

[0078] S2. Add 80.0 mL of deoxygenated deionized water to 5.2 g of hydrochloric acid solution of platinum chloride (Pt 3.8%), and transfer it to a pear-shaped funnel.

[0079] The operations of S3 - S4 are the same as those in Example 1 to prepare the Pt - Cu / AC catalyst, denoted as Cat 5.

[0080] Comparative Example 1

[0081] Weigh 3.0 g of Ni(NO3)2·6H2O and add it to 6.1 ml of a palladium source solution (with a concentration of 0.033 g Pd / mL). Add 80.0 ml of distilled water and dilute evenly. Take 20 g of coconut shell activated carbon pretreated with 5% nitric acid, add it to the above solution, impregnate for more than 2 h, and then dry at 110 °C for 4 h. Pass a nitrogen-hydrogen mixed gas (nitrogen:hydrogen = 3:1) for temperature-raising reduction treatment. The reduction temperature is 400 °C and the reduction time is 2 h to obtain the Pd-Ni / AC catalyst, denoted as catalyst Cat D1.

[0082] Comparative Example 2

[0083] Weigh 0.4 g of rhodium(III) chloride hydrate (Rh 38.5% - 42.5%), add 80.0 ml of distilled water and dilute evenly. Take 20 g of coconut shell activated carbon pretreated with 5% nitric acid, add it to the above solution, impregnate for more than 2 h, and then dry at 110 °C for 4 h. Pass a nitrogen-hydrogen mixed gas (nitrogen:hydrogen = 3:1) for temperature-raising reduction treatment. The reduction temperature is 400 °C and the reduction time is 2 h to obtain the Rh / AC catalyst, denoted as catalyst Cat D2.

[0084] Comparative Example 3

[0085] Weigh 8.5 g of K2CO3·1.5H2O, 3.8 g of Cu(NO3)2·3H2O, and 9.9 g of Ni(NO3)2·6H2O, add 80.0 ml of distilled water to dissolve, add 20 g of CaO solid powder, stir for 600 minutes, filter, dry, add a binder and extrude into pellets, and dry in an oven at 110 °C for 12 h to obtain a catalyst precursor. Crush and screen the catalyst precursor to 80 - 40 mesh, load it into a reaction tube, treat it with N2 at 110 °C for 2 h, raise the temperature to 350 °C within 2 h, and calcine at 350 °C for 2 h; naturally cool to 200 °C, pass HF and treat it at 200 °C for 1.5 h, raise the temperature to 300 °C within 2 h, treat it at 300 °C for 1 h, raise the temperature to 360 °C within 1 h, and continue to activate at 360 °C for 2 h to obtain the K-Cu-Ni / CaF2 catalyst, denoted as catalyst Cat D3.

[0086] Example 6

[0087] This example provides a method for the one-step preparation of 1,1,1,4,4,4-hexafluoro-2-butyne by hydrodechlorination of 2,3-dichloro-1,1,1,4,4,4-hexafluoro-2-butene, specifically as follows:

[0088] 10.0 g of the catalysts (70 nm - 100 nm) of Examples 1 - 5 and Comparative Examples 1 - 2 were respectively loaded into an Inconel 600 alloy reactor with an inner diameter of 10 mm and a length of 500 mm. Nitrogen gas (flow rate 30 mL / min) was introduced and the reaction furnace temperature was gradually increased to 300 °C. After the temperature was reached, the nitrogen gas introduction was stopped and replaced with a mixture of 2,3 - dichloro - 1,1,1,4,4,4 - hexafluoro - 2 - butene and hydrogen. The content of 2,3 - dichloro - 1,1,1,4,4,4 - hexafluoro - 2 - butene in the mixture of 2,3 - dichloro - 1,1,1,4,4,4 - hexafluoro - 2 - butene was 70% - 100%, and the mixture contained 1,1,1 - trichlorotrifluoroethane, 1,1 - difluoro - 1,2,2 - trichloroethane, and 2,2 - difluorotetrachloroethane. Based on the actual content of 2,3 - dichloro - 1,1,1,4,4,4 - hexafluoro - 2 - butene, the raw material ratio V H2 :V CFO-1316 = 2:1, the reaction temperature was 250 - 380 °C, the operating pressure was atmospheric pressure, and the raw material space velocity was 300 - 1200 h -1 . The reaction products were analyzed by gas chromatography, and the results are shown in Table 1:

[0089] Table 1 Reaction evaluation results of different catalysts

[0090]

[0091] From the catalyst activity evaluation results in Table 1, it can be seen that the catalyst of the present invention has excellent performance. Through one - step catalytic hydrogenation reaction, 1,1,1,4,4,4 - hexafluoro - 2 - butyne can be obtained with high selectivity. The catalyst of Comparative Example 1 did not form a hollow structure, and the diffusion time of the product 1,1,1,4,4,4 - hexafluoro - 2 - butyne inside the catalyst particles was relatively long, and further hydrogenation produced 1,1,1,4,4,4 - hexafluoro - 2 - butene. Therefore, the main products were partial hydrogenation products HFO - 1336 and HCFO - 1326, and the selectivity of the target product HFB was relatively low. The catalyst of Comparative Example 2 had too high hydrogenation activity. Although CFO - 1316 participated in the reaction and was converted, the product was mainly the fully hydrogenated product 1,1,1,4,4,4 - hexafluorobutane.

[0092] Comparing the catalysts of Example 3 in mixtures with different CFO - 1316 contents, they had comparable raw material conversion rates and product selectivities. It can be seen that the catalyst of the present invention has the advantages of directional selective catalysis for hydrogenation and excellent anti - poisoning performance.

Claims

1. A gas-phase preparation method of 1,1,1,4,4,4-hexafluoro-2-butyne, characterized in that: Using a mixture of 2,3-dichloro-1,1,1,4,4,4-hexafluoro-2-butene and hydrogen as raw materials, under the action of a particulate catalyst, 1,1,1,4,4,4-hexafluoro-2-butyne is obtained through a one-step hydrodechlorination reaction; the catalyst includes a carbon carrier and an active phase in the form of hollow spheres supported on the carbon carrier, and the active phase includes: A first metal selected from at least one of silver, copper, nickel, and cobalt; A second metal selected from at least one of palladium, platinum, and rhodium; The reduction potential of the first metal is lower than that of the second metal; The catalyst is prepared by an electrochemical replacement method, which specifically includes the following steps: A1. The steps of impregnation, drying, and reduction of the first metal soluble salt solution on the carbon carrier, and the obtained carbon carrier loaded with the first metal is ultrasonically dispersed in water or ethylene glycol to form a slurry; A2. While stirring, a soluble salt solution of the second metal is dropped into the slurry, and after dropping, the reaction continues for 2 to 3 hours; A3. Filter, and the filter cake is washed with deoxygenated deionized water and ethanol until neutral and then dried to obtain the catalyst; In the mixture of 2,3-dichloro-1,1,1,4,4,4-hexafluoro-2-butene, the mass percentage content of 2,3-dichloro-1,1,1,4,4,4-hexafluoro-2-butene ≥ 60%.

2. The gas-phase preparation method of 1,1,1,4,4,4-hexafluoro-2-butyne according to claim 1, characterized in that: In the catalyst, the mass percentage content of the first metal is 0.2 to 10.0%, the mass percentage content of the second metal is 0.1 to 5.0%, and the rest is the carrier.

3. The gas-phase preparation method of 1,1,1,4,4,4-hexafluoro-2-butyne according to claim 2, characterized in that: In the catalyst, the mass percentage content of the first metal is 0.2 to 6.0%, the mass percentage content of the second metal is 0.5 to 2.0%, and the rest is the carrier.

4. The gas-phase preparation method of 1,1,1,4,4,4-hexafluoro-2-butyne according to claim 1, characterized in that: In the mixture of 2,3-dichloro-1,1,1,4,4,4-hexafluoro-2-butene, the mass percentage content of 2,3-dichloro-1,1,1,4,4,4-hexafluoro-2-butene ≥ 70%.

5. The gas-phase preparation method of 1,1,1,4,4,4-hexafluoro-2-butyne according to claim 4, characterized in that: The mixture of 2,3-dichloro-1,1,1,4,4,4-hexafluoro-2-butene includes at least one of 1,1,1-trichlorotrifluoroethane, 1,1-difluoro-1,2,2-trichloroethane, and 2,2-difluorotetrachloroethane.

6. The gas-phase preparation method of 1,1,1,4,4,4-hexafluoro-2-butyne according to claim 1, characterized in that: The molar ratio of 2,3-dichloro-1,1,1,4,4,4-hexafluoro-2-butene to hydrogen in the mixture of 2,3-dichloro-1,1,1,4,4,4-hexafluoro-2-butene is 1:1.2 to 5.

7. The gas-phase preparation method of 1,1,1,4,4,4-hexafluoro-2-butyne according to claim 1, characterized in that: The reaction temperature is 250 to 450 °C, the reaction pressure is atmospheric pressure to 1.0 MPa, and the feed space velocity is 20 to 1500 h -1 .

8. The gas-phase preparation method of 1,1,1,4,4,4-hexafluoro-2-butyne according to claim 1, characterized in that: The carbon carrier is activated carbon pretreated with a 2% to 70 wt% nitric acid solution or sodium hydroxide solution.

9. The gas-phase preparation method of 1,1,1,4,4,4-hexafluoro-2-butyne according to claim 1, characterized in that: The first metal soluble salt is selected from the chloride, nitrate, sulfate, or organic salt of the first metal; the second metal soluble salt is selected from the chloride or nitrate of the second metal.

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