Catalyst composition for synthesizing hexafluoropropylene dimer, preparation method of catalyst composition and synthesis method of hexafluoropropylene dimer

Abstract

The invention relates to a catalyst, in particular to a catalyst composition for synthesizing a hexafluoropropylene dimer, a preparation method of the catalyst composition and a synthesis method of the hexafluoropropylene dimer, the catalyst composition comprises a catalyst A and a carrier A, the carrier A is selected from at least one of activated aluminum oxide and fluorinated-aluminum oxide; the main catalytic component A is selected from at least one of nickel oxide, magnesium oxide, manganese oxide and calcium oxide; the co-catalysis component A is selected from at least one of zirconium oxide, praseodymium oxide, neodymium oxide, lanthanum oxide and cerium oxide; the carrier B is selected from at least one of activated carbon and graphite; the main catalytic component B is selected from at least one of cesium fluoride and rubidium fluoride; and the co-catalysis component B is selected from at least one of copper fluoride, potassium fluoride and iron trifluoride. Compared with the prior art, the defect that the conversion rate, the selectivity and the service life are difficult to reach the standard at the same time in the prior art is overcome. The catalyst system designed by the invention can realize excellent catalytic activity and very long catalyst life.

Description

Technical Field

[0001] The invention relates to a catalyst, in particular to a catalyst combination for synthesizing hexafluoropropylene dimer and a preparation method thereof, and a method for synthesizing hexafluoropropylene dimer. Background Art

[0002] Hexafluoropropylene dimer, abbreviated as HFPD, is generally obtained by dimerization of hexafluoropropylene. Since it contains a carbon-carbon double bond structure, it can easily undergo various chemical reactions to obtain fluorine-containing derivatives. It can be used as a pharmaceutical intermediate, fluorine surfactant, fire extinguishing agent substitute and solvent, etc.

[0003] Hexafluoropropylene dimer has multiple isomers, mainly perfluoro-4-methyl-2-pentene (both cis and trans isomers), perfluoro-2-methyl-2-pentene and other isomers. Currently, there are many research papers and patents published on the reaction of hexafluoropropylene dimerization.

[0004] Patent US4296265A uses CsF or KF as a catalyst, and the hexafluoropropylene gas is reacted at a temperature of 200-250°C to obtain a hexafluoropropylene dimer with a molar yield of 60-83% and a single-pass conversion rate of 60-76%. Patent US4377717 directly uses activated carbon as a catalyst, and passes the hexafluoropropylene gas through a heat-resistant tube filled with activated carbon particles at a temperature of 410-420°C to obtain a hexafluoropropylene dimer with a single-pass conversion rate of about 30% and a yield of 70-80%. The reaction temperature and reaction conditions of this method are very harsh, and the product yield and selectivity are not high.

[0005] It can be seen that the method for synthesizing hexafluoropropylene dimer compounds in the prior art mainly includes using various fluoroolefins as starting materials, using various catalysts to catalyze these raw materials to react, so as to obtain the target product. However, these prior art reaction processes all have serious defects, such as too complicated process steps, low target product yield, and difficulty in actual industrialization. In the reaction process, complex organic matter must be used (for example, the catalyst used in some prior art contains macromolecular crown ethers, organic impregnation liquid dimethyl sulfoxide, etc.), and industrial three wastes are easily generated in the reaction process. In addition, the catalyst used in the prior art often contains toxic components (for example, metallic chromium, etc.), the service life of the catalyst is short, and the catalytic activity is also unsatisfactory, and the raw material conversion rate and target product selectivity are often on the low side (these two indicators of the prior art are usually lower than 90%, and some are even lower than 70%).

[0006] In summary, the above-mentioned defects of the prior art and the growing demand for hexafluoropropylene dimer in the field form a huge contradiction, and people are eager to develop a new technology that can solve the above-mentioned problems. Summary of the invention

[0007] The purpose of the present invention is to provide a catalyst combination for the synthesis of hexafluoropropylene dimer and a preparation method thereof, and a method for synthesizing hexafluoropropylene dimer in order to solve at least one of the above problems, so as to solve the shortcomings of the prior art that the conversion rate, selectivity and life are difficult to achieve the target at the same time. In view of this problem to be solved urgently, the applicant has conducted a lot of in-depth research and unexpectedly found that the use of the catalyst system specially designed by the present invention can achieve excellent catalytic activity and a very long catalyst life. In addition, the catalyst of the present invention can be prepared by an extremely simple process, completely avoiding the use of toxic components, thereby solving safety-related problems.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] The first aspect of the present invention discloses a catalyst combination for the synthesis of hexafluoropropylene dimer, comprising catalyst A and catalyst B;

[0010] The catalyst A comprises:

[0011] Carrier A is at least one selected from activated alumina and fluorinated-alumina (surface-fluorinated alumina);

[0012] The main catalytic component A is at least one selected from nickel oxide, magnesium oxide, manganese oxide and calcium oxide;

[0013] The catalyst promoter component A is at least one selected from zirconium oxide, praseodymium oxide, neodymium oxide, lanthanum oxide and cerium oxide;

[0014] The catalyst B comprises:

[0015] Carrier B is at least one selected from activated carbon and graphite;

[0016] The main catalytic component B is selected from at least one of cesium fluoride and rubidium fluoride;

[0017] The co-catalyst component B is selected from at least one of copper fluoride, potassium fluoride and ferric trifluoride.

[0018] Preferably, the weight ratio of the main catalytic component A to the auxiliary catalytic component A is 1:0.05-0.5; the weight ratio of the carrier A to the total catalytic component A is 1:0.01-0.6, wherein the total catalytic component A includes the main catalytic component A and the auxiliary catalytic component A.

[0019] Preferably, the weight ratio of the main catalytic component B to the auxiliary catalytic component B is 1:0.05-0.5; the weight ratio of the carrier B to the total catalytic component B is 1:0.01-0.6, wherein the total catalytic component B includes the main catalytic component B and the auxiliary catalytic component B.

[0020] Preferably, the weight ratio of the catalyst A to the catalyst B is 1:0.5-3.

[0021] Preferably, the surface area of ​​the carrier A is 50-600m 2 / g, and the volume is 0.1-0.65mL / g.

[0022] Preferably, the surface area of ​​the carrier B is 50-1600m 2 / g, and the volume is 0.1-0.85mL / g.

[0023] The second aspect of the present invention discloses a method for preparing a catalyst combination for synthesizing hexafluoropropylene dimer as described above, comprising the following steps:

[0024] Step 1: preparing a precursor mixed liquid A in which a main catalytic component A precursor and a co-catalytic component A precursor are dissolved, and preparing a precursor mixed liquid B in which a main catalytic component B and a co-catalytic component B are dissolved;

[0025] Step 2: Mixing carrier A with precursor mixed solution A to form mixed material A, and mixing carrier B with precursor mixed solution B to form mixed material B;

[0026] Step 3: adding an alkaline solution to the mixed material A to cause precipitation, followed by filtering, drying and calcining to obtain a catalyst A;

[0027] Step 4: Heat and evaporate the mixed material B, then dry and calcine to obtain catalyst B.

[0028] More specific:

[0029] Catalyst A:

[0030] Step 1: preparing a precursor mixed solution A in which a main catalytic component A precursor and a co-catalytic component A precursor are dissolved;

[0031] Step 2: Mixing carrier A with precursor mixed solution A to form mixed material A;

[0032] Step 3: adding an alkaline solution to the mixed material A to cause precipitation, followed by filtering, drying and calcining to obtain a catalyst A;

[0033] Catalyst B:

[0034] Step 1: preparing a precursor mixed solution B in which a main catalytic component B and a co-catalytic component B are dissolved;

[0035] Step 2: Mixing carrier B with precursor mixed solution B to form mixed material B;

[0036] Step 3: heating and evaporating the mixed material B, followed by drying and calcining to obtain catalyst B.

[0037] Preferably, it includes one or more of the following:

[0038] i) In step 1, the main catalytic component A precursor is a soluble salt of the metal element in the main catalytic component A, and the co-catalytic component A precursor is a soluble salt of the metal element in the co-catalytic component A;

[0039] ii) in step 3, the alkaline solution comprises aqueous ammonia; the drying is carried out at 100-130° C. for 8-12 hours; the calcination is carried out at 400-500° C. for 6-12 hours in a nitrogen atmosphere;

[0040] iii) In step 4, the drying is carried out at 100-130°C for 8-12 hours; and the calcination is carried out at 500-550°C for 2-5 hours.

[0041] The third aspect of the present invention discloses a method for synthesizing hexafluoropropylene dimer, using any of the above-mentioned catalyst combinations for synthesizing hexafluoropropylene dimer as a catalyst for the synthesis reaction;

[0042] The synthesis method comprises:

[0043] Hexafluoropropylene and a protective carrier gas are introduced into a reactor loaded with a catalyst combination to undergo a catalytic reaction and generate a hexafluoropropylene dimer;

[0044] The reactor is a tubular reactor or a shell-and-tube reactor;

[0045] The catalyst A is loaded on the upper part of the isothermal zone of the reactor, and the catalyst B is loaded on the lower part of the isothermal zone of the reactor.

[0046] Preferably, it includes one or more of the following:

[0047] i) the protective carrier gas is selected from one or more of nitrogen, helium, neon and argon;

[0048] ii) the molar ratio of hexafluoropropylene to protective carrier gas is 1:0.1-12;

[0049] iii) The total space velocity of the hexafluoropropylene and the protective carrier gas is 200-3000h -1 ;

[0050] iv) The temperature of the catalytic reaction is 220-420° C. and the pressure is 0.1-1.0 MPa.

[0051] The working principle of the present invention is:

[0052] The inventors have found that the reaction activity of catalyst A as a single catalytic reaction is weak, with a conversion rate of about 80-90%, but the selectivity is high, up to more than 98%, and the catalyst life is long; the reaction activity of catalyst B as a single catalytic reaction is strong, with a high conversion rate of up to 98%, but the selectivity is only about 80-90%, and the catalyst life is short; the inventors have further studied that through the joint action of the two catalysts, a good synergistic effect can be formed. In the early stage of the reaction process, more than 80% of the product is converted through catalyst A, and a high conversion rate and selectivity are obtained. The material in the later stage of the reaction can be converted into the remaining product through catalyst B, and a high selectivity is obtained. Through the coordination effect, a high conversion rate, high selectivity, and a long catalyst life are obtained, which can be used in industrial production.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] The catalyst combination of the present invention can be used to catalyze the preparation of hexafluoropropylene dimer by hexafluoropropylene catalytic synthesis reaction with extremely high catalytic activity, achieving the advantages of improved reaction yield, target product selectivity, easy control of catalytic reaction conditions, long catalyst life, etc.

[0055] The present invention provides a multi-active component supported catalyst combination, wherein the catalyst combination comprises two groups of catalysts of different types respectively loaded in an upper isothermal zone (catalyst A) and a lower isothermal zone (catalyst B) in a same tubular reactor, so that hexafluoropropylene undergoes a catalytic reaction through the catalyst reactor and generates hexafluoropropylene dimer. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 The conversion rate and selectivity of the catalyst combination in Application Example 1 after 600 hours of catalytic reaction.

[0057] Figure 2 This is the chromatographic analysis spectrum of the catalyst product of the catalyst combination in Application Example 1 after 600 hours of catalytic reaction. DETAILED DESCRIPTION

[0058] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0059] In the following description, unless otherwise specified, the reagents used are conventional commercially available products, and the methods used are well known in the art.

[0060] The catalyst combination described in this scheme is two groups of different supported catalysts respectively loaded in the upper part of the isothermal zone (catalyst A) and the lower part of the isothermal zone (catalyst B) in the same tubular reactor; the supported catalyst comprises a main catalytic component and a co-catalytic component supported on a carrier,

[0061] The carrier of catalyst A is selected from at least one of the following: activated alumina and fluorinated-alumina;

[0062] The main catalytic component is selected from at least one of the following: nickel oxide, magnesium oxide, manganese oxide, calcium oxide or a combination thereof; the co-catalytic component is selected from one or more of the following: zirconium oxide, praseodymium oxide, neodymium oxide, lanthanum oxide, cerium oxide or a combination thereof.

[0063] Catalyst B is a supported catalyst, comprising a main catalytic component and a co-catalytic component supported on a carrier, wherein the carrier is one or a combination of high specific surface area activated carbon and graphite, the main catalytic component is selected from: cesium fluoride, rubidium fluoride or a combination thereof; the co-catalyst component is selected from one or more of the following: copper fluoride, potassium fluoride, iron (III) fluoride or a combination thereof.

[0064] The weight ratio of the main catalytic component to the auxiliary catalytic component is 1:0.05 to 1:0.5, and the weight ratio of the weight of the carrier to the total weight of the main catalytic component and the auxiliary catalytic component is carrier: (main catalytic component + auxiliary catalytic component) = 1:0.01 to 1:0.6.

[0065] The catalyst A and catalyst B are used in a weight ratio of 1:0.5 to 1:3.

[0066] The surface area of ​​the catalyst A carrier is 50-600m 2 / g, pore volume is 0.1mL / g-0.65mL / g. Catalyst B carrier is a porous carrier with a specific surface area of ​​50-1600m 2 / g, and the specific pore volume is 0.1mL / g-0.85mL / g.

[0067] A method for synthesizing a supported catalyst comprises:

[0068] Step 1: providing one or more precursor solutions or precursor suspensions containing a main catalytic component and a co-catalytic component;

[0069] Step 2: mixing the precursor solution or the precursor suspension with the carrier to form a mixed material;

[0070] Step 3: Heat the mixed material until dry, and then calcine it to obtain a supported catalyst.

[0071] or, including:

[0072] Step 1: providing one or more precursor solutions or precursor suspensions containing a main catalytic component and a co-catalytic component;

[0073] Step 2: mixing the precursor solution or the precursor suspension with the carrier to form a mixed material;

[0074] Step 3: adding an alkali solution to the mixed material to precipitate the metal element, followed by filtering, drying and subsequently calcining to obtain a supported catalyst.

[0075] A method for preparing hexafluoropropylene dimer from hexafluoropropylene, in the presence of the above-mentioned supported catalyst, allows hexafluoropropylene to undergo a catalytic reaction and generate hexafluoropropylene dimer.

[0076] The reaction equation is as follows:

[0077]

[0078] Note: This reaction equation only represents the main hexafluoropropylene dimer component, does not include trace amounts of other types of isomers, and does not distinguish between cis- and trans-isomers and other structures.

[0079] Specifically, the method comprises introducing hexafluoropropylene and a protective carrier gas into a reactor containing the above-mentioned supported catalyst, so that the hexafluoropropylene undergoes a catalytic reaction and generates a hexafluoropropylene dimer;

[0080] The protective carrier gas is selected from one or more of the following: nitrogen, helium, neon, argon;

[0081] and the molar ratio of hexafluoropropylene to protective carrier gas is 1:0.1 to 1:12;

[0082] And the total space velocity of hexafluoropropylene and protective carrier gas is 200-3,000 hours -1 .

[0083] More preferably, the protective carrier gas is nitrogen, and the molar ratio of hexafluoropropylene to the protective carrier gas is 1:0.1 to 1:3.

[0084] The reaction temperature of the catalytic (rearrangement) reaction is 220-420° C.; the reaction pressure of the catalytic (rearrangement) reaction is 0.1-1.0 MPa; the catalytic (rearrangement) reaction is carried out in a reactor selected from the following: a tubular reactor, a shell-and-tube reactor.

[0085] Example 1

[0086] Catalyst A1: 100 g of aluminum chloride was dissolved in 1000 g of deionized water, and then 15 g of nickel nitrate and 1.5 g of zirconium nitrate were added to the aqueous solution, and a small amount of nitric acid was added to promote dissolution, and the mixture was stirred thoroughly to form a uniform mixture. Ammonia water was then added to the mixture to cause precipitation, and the resulting precipitate was filtered, and the resulting solid was dried at 110°C for 10 hours, and then transferred to a muffle furnace and calcined at 450°C in a nitrogen atmosphere for 8 hours. Catalyst A1 was obtained: nickel oxide-zirconium oxide / aluminum oxide catalyst, hereinafter referred to as catalyst A1, and its specific surface area was found to be 357 m 2 / g, and the pore volume is 0.35mL / g.

[0087] Catalyst B1: Dissolve 50 grams of cesium fluoride and rubidium fluoride in a mass ratio of 1:1 in 1000 grams of deionized water, then add 5 grams of copper fluoride to the aqueous solution, add a little nitric acid to promote dissolution, and stir thoroughly to form a uniform mixture. Then add 350 grams of activated carbon to the mixture, stir the resulting mixture containing activated carbon continuously, and heat it at 110°C while stirring until the water in the mixture is evaporated. The obtained solid is dried at 110°C for 10 hours, then transferred to a muffle furnace and calcined at 520°C for 3 hours. That is, a cesium fluoride-rubidium fluoride-copper fluoride activated carbon catalyst is obtained, which will be referred to as catalyst B1 below. Catalyst B1 is a porous carrier with a specific surface area of ​​1170m 2 / g, and the specific pore volume is 0.67mL / g.

[0088] Example 2

[0089] Catalyst A2: Dissolve 90 grams of aluminum chloride and 10 grams of aluminum fluoride in 1000 grams of deionized water. If they cannot be completely dissolved, they can be suspended in the solution; then add 10 grams of nickel nitrate, 3 grams of magnesium nitrate and 1.5 grams of neodymium nitrate to the aqueous solution, and add a little nitric acid to promote dissolution, and stir thoroughly to form a uniform mixture. Then add ammonia water to the mixture to precipitate. The resulting precipitate is filtered, and the resulting solid is dried at 120°C for 10 hours, then transferred to a muffle furnace and calcined at 550°C in a nitrogen atmosphere for 8 hours. Catalyst A2 is obtained: nickel oxide-magnesium-neodymium / fluorinated aluminum oxide catalyst, hereinafter referred to as catalyst A2. Analysis and testing show that its specific surface area is 407m 2 / g, and the pore volume is 0.33mL / g. .

[0090] Catalyst B2: Dissolve 50 grams of cesium fluoride in 1000 grams of deionized water, then add 5 grams of potassium fluoride to the aqueous solution, add a little nitric acid to promote dissolution, and stir thoroughly to form a uniform mixture or suspension. Then add 350 grams of graphite / activated carbon with a mass ratio of 2:5 to the mixture, and continue to stir the resulting mixture containing graphite / activated carbon, and heat it at 120°C while stirring until the water in the mixture is evaporated. The obtained solid is dried at 120°C for 10 hours, then transferred to a muffle furnace and calcined at 520°C for 3 hours. That is, a cesium fluoride-potassium fluoride / graphite-activated carbon catalyst is obtained, which will be referred to as catalyst B2 below. The catalyst B2 carrier is a porous carrier with a specific surface area of ​​870m 2 / g, and the specific pore volume is 0.56mL / g.

[0091] Application Example 1

[0092] During the reaction, a nickel tubular reactor with a diameter of 12 mm and a length of 350 mm was used, and a heating jacket was provided on the outside of the reactor. 5 g of catalyst A was filled in the upper part of the isothermal zone of the tubular reactor, and 5 g of catalyst B was filled in the lower part of the isothermal zone. First, the reaction was heated for 1000 hours. -1 Nitrogen was introduced into the reactor at a space velocity of 1.5 ℃, and the reactor was heated to 200°C for 2 hours to dry the catalyst. After drying, hexafluoropropylene and nitrogen were mixed in a molar ratio of 10:2 by a premixer-preheater to form a mixed gas, which was preheated to 250°C and then heated for 1000 hours. -1 The reaction was carried out at a temperature of 280°C and a pressure of 0.2 MPa in the reactor.

[0093] The catalyst combinations A1+B1, A2+B2, A1+B2, and A2+B1 were tested according to the above reaction process. The reaction results are shown in Table 1.

[0094] Table 1 Summary of catalytic reaction results

[0095] Catalyst combination used Conversion rate / % Selectivity / % Catalyst A1+B1 99.9 99.4 Catalyst A2+B2 99.5 98.8 Catalyst A1+B2 99.1 99.5 Catalyst A2+B1 99.2 99.3

[0096] The catalyst characterization results are cumulative calculated values ​​for 200 h.

[0097] Characterization of catalyst life:

[0098] Catalyst A1+B1 was used to carry out the catalytic reaction according to the steps given in Application Example 1, and the catalytic reaction was continued for 600 hours. The curve graph of the measured conversion rate and selectivity over time is shown in Figure 1 This solution can significantly reduce the content of hexafluoropropylene trimer, basically keeping it below 0.5%. Figure 2 As shown, it is a chromatographic analysis of the sampled products during the catalytic reaction, wherein the peaks at retention times 10.934 and 11.087 are both hexafluoropropylene dimer mixtures (including cis and trans isomers), and the peaks at retention times 12.555 and 13.482 are hexafluoropropylene trimer mixtures (including cis and trans isomers). It can be seen that the basic trimer content in the catalytic product is 0.35%, the dimer content is greater than 99.6%, and no hexafluoropropylene raw material is detected, indicating that the catalyst combination using this scheme has extremely high conversion rate and selectivity.

[0099] For catalyst A1+B1, after 600 hours of catalytic reaction, its cumulative conversion rate was 99.2% and the target product selectivity was 99.0%, which still maintained at an excellent level, indicating that its service life can reach at least 600 hours.

[0100] Comparative Example 1

[0101] The catalyst prepared in Example 3 of CN117504902 was used as the comparative example, with 10% cesium fluoride and 90% aluminum fluoride, and the reaction was carried out at 250°C for 5 hours. The conversion rate was 95.5%, the dimer selectivity was 88.7%, and the trimer was 10.8%; the reaction was continued for 100 hours, and the conversion rate was 75.5%, the dimer selectivity was 77.9%, and the trimer was 21.3% after sampling and analysis; it can be seen that the catalyst was obviously deactivated.

[0102] Example 3

[0103] This embodiment is basically the same as Embodiment 1, except that:

[0104] In catalyst A, the main catalytic component A is magnesium oxide and calcium oxide (prepared by magnesium nitrate and calcium nitrate), and the co-catalytic component A is praseodymium oxide, lanthanum oxide and cerium oxide (prepared by praseodymium nitrate, lanthanum nitrate and cerium nitrate).

[0105] In catalyst B, carrier B is a graphite / activated carbon mixture, main catalytic component B is cesium fluoride, and co-catalytic component B is potassium fluoride and ferric trifluoride.

[0106] Example 4

[0107] This embodiment is basically the same as Embodiment 1, except that:

[0108] In catalyst A, 100 g of aluminum chloride is dissolved in 1000 g of deionized water, and then 25 g of nickel nitrate and 3 g of zirconium nitrate are added to the aqueous solution, and a small amount of nitric acid is added to promote dissolution, and the mixture is stirred thoroughly to form a uniform mixture. Ammonia water is then added to the mixture to cause precipitation, and the resulting precipitate is filtered, and the resulting solid is dried at 100° C. for 12 hours, and then transferred to a muffle furnace and calcined at 500° C. for 6 hours in a nitrogen atmosphere. Catalyst A: nickel oxide-zirconium oxide / aluminum oxide catalyst is obtained.

[0109] Catalyst B: Dissolve 50 grams of cesium fluoride and rubidium fluoride in a mass ratio of 1:1 in 1000 grams of deionized water, then add 10 grams of copper fluoride to the aqueous solution, add a little nitric acid to promote dissolution, and stir thoroughly to form a uniform mixture. Then add 400 grams of activated carbon to the mixture, stir the resulting mixture containing activated carbon continuously, and heat it at 110°C while stirring until the water in the mixture is evaporated. The obtained solid is dried at 130°C for 8 hours, then transferred to a muffle furnace and calcined at 550°C for 2 hours. That is, a cesium fluoride-rubidium fluoride-copper fluoride activated carbon catalyst is obtained.

[0110] Example 5

[0111] This embodiment is basically the same as Embodiment 1, except that:

[0112] In catalyst A, 100 g of aluminum chloride is dissolved in 1000 g of deionized water, and then 40 g of nickel nitrate and 10 g of zirconium nitrate are added to the aqueous solution, and a small amount of nitric acid is added to promote dissolution, and the mixture is stirred thoroughly to form a uniform mixture. Ammonia water is then added to the mixture to cause precipitation, and the resulting precipitate is filtered, and the resulting solid is dried at 130° C. for 8 hours, and then transferred to a muffle furnace and calcined at 400° C. for 12 hours in a nitrogen atmosphere. Catalyst A: nickel oxide-zirconium oxide / aluminum oxide catalyst is obtained.

[0113] Catalyst B: Dissolve 50 grams of cesium fluoride and rubidium fluoride in a mass ratio of 1:1 in 1000 grams of deionized water, then add 20 grams of copper fluoride to the aqueous solution, add a little nitric acid to promote dissolution, and stir thoroughly to form a uniform mixture. Then add 300 grams of activated carbon to the mixture, stir the resulting mixture containing activated carbon continuously, and heat it at 110°C while stirring until the water in the mixture is evaporated. The obtained solid is dried at 100°C for 12 hours, then transferred to a muffle furnace and calcined at 500°C for 5 hours. That is, a cesium fluoride-rubidium fluoride-copper fluoride activated carbon catalyst is obtained.

[0114] Application Example 2

[0115] This application example is basically the same as application example 1, except that the protective carrier gas used is a mixture of helium and argon, the molar ratio of hexafluoropropylene to the protective carrier gas is 10:12, and the total air velocity is 2000h -1 .

[0116] Application Example 3

[0117] This application example is basically the same as application example 1, except that the protective carrier gas used is neon, the molar ratio of hexafluoropropylene to protective carrier gas is 10:6, and the total air velocity is 3000h -1 .

[0118] Application Example 4

[0119] This application example is basically the same as application example 1, except that the molar ratio of hexafluoropropylene to protective carrier gas is 10:1, and the total air velocity is 200 h -1 .

[0120] Application Example 5

[0121] This application example is basically the same as application example 1, except that the temperature of the catalytic reaction is 220° C. and the pressure is 0.6 MPa.

[0122] Application Example 6

[0123] This application example is basically the same as application example 1, except that the temperature of the catalytic reaction is 320° C. and the pressure is 0.1 MPa.

[0124] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

[0125] It should also be noted that, although several catalysts for dimerization reactions have been reported in the prior art, all catalysts reported in the prior art are different from the catalysts of the present application, or the dimerization reactions reported are dimerization reactions of perfluorinated or fluorinated reaction raw materials that are completely different from those of the present application; it is well known in the art that catalysts and / or process conditions suitable for dimerization reactions of other specific different reaction raw materials cannot be simply used for the catalytic dimerization reaction of the reaction raw materials of the present invention.

Claims

1. A catalyst combination for the synthesis of hexafluoropropylene dimer, characterized in that: comprising catalyst A and catalyst B; The catalyst A comprises: Carrier A is at least one selected from activated alumina and fluorinated alumina; The main catalytic component A is at least one selected from nickel oxide, magnesium oxide, manganese oxide and calcium oxide; The catalyst promoter component A is at least one selected from zirconium oxide, praseodymium oxide, neodymium oxide, lanthanum oxide and cerium oxide; The catalyst B comprises: Carrier B is at least one selected from activated carbon and graphite; The main catalytic component B is selected from at least one of cesium fluoride and rubidium fluoride; The co-catalyst component B is selected from at least one of copper fluoride, potassium fluoride and ferric trifluoride.

2. A catalyst combination for the synthesis of hexafluoropropylene dimer according to claim 1, characterized in that: The weight ratio of the main catalytic component A to the auxiliary catalytic component A is 1:0.05-0.5; the weight ratio of the carrier A to the total catalytic component A is 1:0.01-0.6, wherein the total catalytic component A includes the main catalytic component A and the auxiliary catalytic component A.

3. The catalyst combination for the synthesis of hexafluoropropylene dimer according to claim 1, characterized in that: The weight ratio of the main catalytic component B to the auxiliary catalytic component B is 1:0.05-0.5; the weight ratio of the carrier B to the total catalytic component B is 1:0.01-0.6, wherein the total catalytic component B includes the main catalytic component B and the auxiliary catalytic component B.

4. The catalyst combination for the synthesis of hexafluoropropylene dimer according to claim 1, characterized in that: The weight ratio of the catalyst A to the catalyst B is 1:0.5-3.

5. The catalyst combination for the synthesis of hexafluoropropylene dimer according to claim 1, characterized in that: The surface area of ​​the carrier A is 50-600m 2 / g, and the volume is 0.1-0.65mL / g.

6. The catalyst combination for the synthesis of hexafluoropropylene dimer according to claim 1, characterized in that: The surface area of ​​the carrier B is 50-1600m 2 / g, and the volume is 0.1-0.85mL / g.

7. A method for preparing a catalyst combination for the synthesis of hexafluoropropylene dimer according to any one of claims 1 to 6, characterized in that: The steps include: Step 1: preparing a precursor mixed liquid A in which a main catalytic component A precursor and a co-catalytic component A precursor are dissolved, and preparing a precursor mixed liquid B in which a main catalytic component B and a co-catalytic component B are dissolved; Step 2: Mixing carrier A with precursor mixed solution A to form mixed material A, and mixing carrier B with precursor mixed solution B to form mixed material B; Step 3: adding an alkali solution to the mixed material A to cause precipitation, followed by filtering, drying and calcining to obtain a catalyst A; Step 4: Heat and evaporate the mixed material B, then dry and calcine to obtain catalyst B.

8. The method for preparing a catalyst combination for the synthesis of hexafluoropropylene dimer according to claim 7, characterized in that: Include one or more of the following: i) In step 1, the main catalytic component A precursor is a soluble salt of the metal element in the main catalytic component A, and the co-catalytic component A precursor is a soluble salt of the metal element in the co-catalytic component A; ii) in step 3, the alkaline solution comprises aqueous ammonia; the drying is carried out at 100-130° C. for 8-12 h; the calcination is carried out at 400-500° C. for 6-12 h in a nitrogen atmosphere; iii) In step 4, the drying is carried out at 100-130°C for 8-12 hours; and the calcination is carried out at 500-550°C for 2-5 hours.

9. A method for synthesizing hexafluoropropylene dimer, characterized in that: Using the catalyst combination for the synthesis of hexafluoropropylene dimer as described in any one of claims 1 to 6 as a catalyst for the synthesis reaction; The synthesis method comprises: Hexafluoropropylene and a protective carrier gas are introduced into a reactor loaded with a catalyst combination to undergo a catalytic reaction and generate a hexafluoropropylene dimer; The reactor is a tubular reactor or a shell-and-tube reactor; The catalyst A is loaded on the upper part of the isothermal zone of the reactor, and the catalyst B is loaded on the lower part of the isothermal zone of the reactor.

10. The method for synthesizing hexafluoropropylene dimer according to claim 9, characterized in that: Include one or more of the following: i) the protective carrier gas is selected from one or more of nitrogen, helium, neon and argon; ii) the molar ratio of hexafluoropropylene to protective carrier gas is 1:0.1-12; iii) The total space velocity of the hexafluoropropylene and the protective carrier gas is 200-3000h -1 ; iv) The temperature of the catalytic reaction is 220-420° C. and the pressure is 0.1-1.0 MPa.

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