Catalyst and preparation method thereof, and preparation method of D2 structure hexafluoropropylene dimer

Abstract

The invention belongs to the field of fluorine chemical industry, and particularly relates to a catalyst and a preparation method thereof, and a preparation method of a D2 structure hexafluoropropylene dimer. The preparation method comprises the following steps: (1) preparing a porous phase transfer cocatalyst of which the surface is modified with silane groups; and 2) dispersing the porous phase transfer cocatalyst obtained in the step 1) into a solvent, and then adding a mixture of potassium fluoride and hydrofluoric acid to obtain the catalyst. According to the technology, the key problems of catalyst deactivation, low product selectivity and the like in a traditional process are solved, the characteristics of low temperature, high efficiency and green circulation better meet the modern chemical clean production requirements, and a technical guarantee is provided for large-scale application of the hexafluoropropylene dimer in the fields of high-end materials, electronic chemicals and the like.

Description

Technical Field

[0001] The invention belongs to the field of fluorine chemical industry, and particularly relates to a catalyst and a preparation method thereof, and a preparation method of a D2 structure hexafluoropropylene dimer. Background Art

[0002] Hexafluoropropylene dimer (HFPD) is an important raw material for fine chemicals, widely used in high-performance coatings, electronic materials, refrigerants, and surfactants. Currently, the main methods for preparing HFPD include gas-phase and liquid-phase methods. The reaction is shown below.

[0003]

[0004] Patent CN117504902A details the vapor phase process for preparing hexafluoropropylene dimer. Catalytic dimerization is carried out at high temperatures of 200-300°C. While its advantage lies in the ease of post-processing, it is limited by technical bottlenecks such as rapid catalyst deactivation and difficulty in regeneration.

[0005] Patent CN118496058A details a method for preparing perfluoro-4-methyl-2-pentene (D2) by the continuous isomerization of hexafluoropropylene dimer perfluoro-4-methyl-2-pentene (D1). While this continuous isomerization process from dimer D1 to D2 offers the advantages of room-temperature reaction and low equipment investment, it requires a two-step oligomerization and isomerization process, resulting in a complex process (reaction time >48 hours), frequent manual intervention, and a trimer impurity content of 8-12% in the product system, severely limiting product purity.

[0006] Existing technology systems generally face three major challenges: (1) the difficulty of balancing catalytic efficiency and selectivity: conventional catalysts have a significant trade-off between D2 selectivity (<85%) and conversion (<90%); (2) environmental friendliness defects: heavy metal catalyst residues lead to increased costs for waste treatment; (3) circular economy bottlenecks: catalyst activity decays by >40% after 3-5 consecutive uses, making it difficult to achieve industrial closed-loop production. Therefore, it is of great significance to develop a synthesis method that is efficient, selective, environmentally friendly, and recyclable. Summary of the Invention

[0007] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for preparing perfluoro-2-methyl-2-pentene.

[0008] To achieve the above object, the technical solution adopted by the present invention is:

[0009] A method for preparing a catalyst for preparing a D2 structure hexafluoropropylene dimer comprises the following steps:

[0010] 1) preparing a porous phase transfer co-catalyst modified with silane groups on its surface;

[0011] 2) The porous phase transfer co-catalyst obtained in step 1) is dispersed in a solvent and then a mixture of potassium fluoride and hydrofluoric acid is added to obtain a catalyst.

[0012] The specific steps of step 1) are: 11) immersing the porous support in a phase transfer compound solution, dispersing it evenly and then drying it to obtain a porous phase transfer co-catalyst loaded with the phase transfer compound; 12) adding a fluorinated organic silane to the porous phase transfer co-catalyst obtained in step 11) to obtain a porous phase transfer co-catalyst with a silane group modified on the surface.

[0013] The porous carrier is a porous carbon material.

[0014] The phase transfer compound is 1,2-bis(triethoxysilyl)ethane (BTEE). Preferably, the concentration of the phase transfer compound is 0.1-1M, preferably 0.5M.

[0015] The fluorinated organic silane is a fluorinated alkyl polyether modified polysiloxane; preferably, the mass volume ratio of the porous phase transfer co-catalyst to the fluorinated organic silane is 1 g: (0.1-2) ml; preferably 1 g / 0.5 mL.

[0016] The specific steps of step 2) are:

[0017] Under nitrogen protection, potassium fluoride was slowly added to a 40% hydrofluoric acid solution cooled in an ice bath at a molar ratio of KF:HF = 1:1, and stirred continuously until completely dissolved to obtain solution A;

[0018] Controlling the reaction temperature to <10°C; ultrasonically dispersing a porous phase transfer catalyst modified with silane groups in a water / alcohol mixture, and adding triethylamine to obtain a solution B; preferably, the volume ratio of water / alcohol is 1:6; preferably, the mass volume ratio of the porous phase transfer catalyst modified with silane groups to the triethylamine is 1g:(0.1-2)ml; preferably, 1g / 1mL;

[0019] Subsequently, solution A and solution B are mixed, stirred for 5 hours, and then the solvent is removed by reduced pressure distillation. After washing and vacuum drying, composite catalyst particles are obtained; preferably, the volume ratio of the solution A to the solution B is 1:(0.6-0.8).

[0020] The present invention also includes a catalyst for preparing D2 structure hexafluoropropylene dimer obtained by the preparation method.

[0021] The present invention also includes a method for preparing a D2 structure hexafluoropropylene dimer, comprising the following steps: adding the catalyst and an organic solvent into a reactor, cooling the reactor, starting stirring, and then introducing hexafluoropropylene into the reactor; after the reaction is completed, opening the reactor, separating the lower layer liquid, and obtaining the target product, the D2 structure hexafluoropropylene dimer.

[0022] The reaction temperature is -5 to 20°C, and the reaction pressure is normal pressure.

[0023] The organic solvent is acetonitrile, diethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether. Compared with the prior art, the present invention has the following beneficial effects:

[0024] This method, through an innovative catalytic system design, achieves efficient, single-step dimerization of hexafluoropropylene under mild conditions (–5 to 20°C). Its key breakthroughs are: ① The catalyst system utilizes composite components with readily available raw materials and a simple preparation process, ensuring high activity (conversion rate ≥90%) and high selectivity (product purity ≥95%). ② The reaction process breaks through the traditional limitations of high temperature and high pressure and can be completed at room temperature, significantly reducing energy consumption (saving over 30% compared to traditional processes) and avoiding byproduct formation (trimer content is undetectable). ③ Industrial application offers significant advantages, reducing production costs by approximately 25% through a shortened reaction pathway (single-step dimerization), simplified post-processing, and catalyst recycling (activity retention >90% after 10 cycles).

[0025] This technology not only solves key problems such as catalyst deactivation and low product selectivity in traditional processes, but its "low temperature, high efficiency and green cycle" characteristics are more in line with the needs of modern chemical clean production, and provide technical support for the large-scale application of hexafluoropropylene dimer in high-end materials, electronic chemicals and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the catalyst for preparing D2 structure hexafluoropropylene dimer.

[0027] Figure 2 This is the infrared image of perfluoro-4-methyl-2-pentene (D2); DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and the best embodiments.

[0029] Example 1

[0030] Preparation method of catalyst for preparing D2 structure hexafluoropropylene dimer ( Figure 1 Flowchart shown), comprising the following steps:

[0031] 1) preparing a porous phase transfer co-catalyst modified with silane groups on its surface;

[0032] 11) Preparation of porous phase transfer co-catalyst: soak the commercially available porous carbon material in dilute hydrochloric acid (1 M) for 12 hours to remove impurities, wash with deionized water until neutral, and dry at 120°C.

[0033] A phase transfer compound (1,2-bis(triethoxysilyl)ethane) was dissolved in ethanol to prepare a 0.5 M solution. The pretreated porous carbon material was immersed in the solution and ultrasonicated for 30 minutes to promote dispersion. The material was heated and stirred for 12 hours, then centrifuged and dried under vacuum at 60°C for 6 hours to obtain a porous phase transfer co-catalyst.

[0034] 12) 1 g of the obtained porous phase transfer co-catalyst was ultrasonically dispersed in a toluene solution, 0.5 mL of fluorinated organosilane (fluoroalkyl polyether-modified polysiloxane) was added, the mixture was stirred at 80° C. for 6 hours, centrifuged, and vacuum-dried at 60° C. for 6 hours to obtain a surface-modified porous phase transfer co-catalyst.

[0035] 2) dispersing the surface-modified porous phase transfer co-catalyst obtained in step 1) in a solvent, and then adding a mixture of potassium fluoride and hydrofluoric acid to obtain a catalyst.

[0036] Specifically, the method comprises the following steps: under nitrogen protection, potassium fluoride (KF) is slowly added to a 40% hydrofluoric acid solution cooled in an ice bath at a molar ratio of KF:HF = 1:1, and continuously stirred until completely dissolved to obtain solution A. The reaction temperature is controlled to be <10°C to avoid decomposition caused by severe exotherm.

[0037] 1 g of surface-modified porous phase transfer catalyst was ultrasonically dispersed in a water / alcohol mixture (1:6), and 1 mL of triethylamine was added to obtain solution B.

[0038] Solution A and solution B were mixed in a mass ratio of 1:1, stirred for 5 hours, and then the solvent was removed by reduced pressure distillation. The composite catalyst particles were obtained after washing and vacuum drying.

[0039] Example 2

[0040] The difference between Example 2 and Example 1 is the amount of potassium bifluoride loaded on the porous carrier. Solution A and Solution B were mixed at a mass ratio of 1:0.8, stirred for 5 hours, and then the solvent was removed by vacuum distillation. The composite catalyst particles were obtained after washing and vacuum drying.

[0041] Example 3

[0042] The difference between Example 3 and Example 1 is the amount of potassium bifluoride loaded on the porous carrier. Solution A and Solution B were mixed at a mass ratio of 1:0.6, stirred for 5 hours, and then the solvent was removed by vacuum distillation. The composite catalyst particles were obtained after washing and vacuum drying.

[0043] Example 4

[0044] The difference between Example 4 and Example 1 is the amount of potassium bifluoride loaded on the porous carrier. Solution A and Solution B were mixed in a mass ratio of 1:2, stirred for 5 hours, and then the solvent was removed by vacuum distillation. The composite catalyst particles were obtained after washing and vacuum drying.

[0045] Comparative Example 1

[0046] The difference between Comparative Example 1 and Example 1 is that the surface of the porous support only contains a porous phase transfer promoter, which specifically includes the following steps: soaking the commercially available porous carbon material in dilute hydrochloric acid (1M) for 12 hours to remove impurities, washing with deionized water until neutral, and drying at 120°C.

[0047] A phase transfer compound (1,2-bis(triethoxysilyl)ethane) was dissolved in ethanol to prepare a 0.5 M solution. The pretreated porous carbon material was immersed in the solution and ultrasonicated for 30 minutes to promote dispersion. The material was heated and stirred for 12 hours, then centrifuged and dried under vacuum at 60°C for 6 hours to obtain a porous phase transfer co-catalyst.

[0048] Comparative Example 2

[0049] The difference between Comparative Example 2 and Example 1 is that the surface of the porous carrier contains only potassium bifluoride, and specifically includes the following steps:

[0050] 1) Preparing a porous carbon material with a surface modified with silane groups; soaking the commercially available porous carbon material in dilute hydrochloric acid (1 M) for 12 hours to remove impurities, washing with deionized water until neutral, and drying at 120°C.

[0051] 1 g of the obtained porous carbon material was dispersed in a toluene solution by ultrasonication, 0.5 mL of fluorinated organosilane (fluoroalkyl polyether-modified polysiloxane) was added, the mixture was stirred at 80°C for 6 hours, and then centrifuged and dried in vacuo at 60°C for 6 hours to obtain a surface-modified porous carbon material;

[0052] 2) The surface-modified porous carbon material obtained in step 1) is dispersed in a solvent, and then a mixture of potassium fluoride and hydrofluoric acid is added to obtain a catalyst.

[0053] Specifically, the method comprises the following steps: under nitrogen protection, potassium fluoride (KF) is slowly added to a 40% hydrofluoric acid solution cooled in an ice bath at a molar ratio of KF:HF = 1:1, and continuously stirred until completely dissolved to obtain solution A. The reaction temperature is controlled to be <10°C to avoid decomposition caused by severe exotherm.

[0054] 1 g of surface-modified porous carbon material was ultrasonically dispersed in a water / alcohol mixture (1:6), and 1 mL of triethylamine was added to obtain solution B.

[0055] Solution A and solution B were mixed in a mass ratio of 1:1, stirred for 5 hours, and then the solvent was removed by reduced pressure distillation. The composite catalyst particles were obtained after washing and vacuum drying.

[0056] The catalysts obtained in Examples 1-4 and Comparative Examples 1-2 were used to prepare D2 structure hexafluoropropylene dimer, specifically comprising the following steps:

[0057] 50g of composite catalyst and diethylene glycol dimethyl ether (20L) were added to a 50L reactor, the reactor was cooled to -5°C, 50g of hexafluoropropylene was introduced into the reactor after stirring was started, and the reaction system was kept at -5-20°C by a circulating cooling vehicle. After the reaction was completed, stirring was continued for 30 minutes, and then the reactor was opened and the lower layer liquid was separated to obtain the target product hexafluoropropylene dimer (perfluoro-2-methyl-2-pentene, D2, infrared Figure 2 shown).

[0058] The final yield of the composite catalyst prepared in Example 1 was 90.1%, and the selectivity was 95%.

[0059] The final yield of the composite catalyst prepared in Example 2 was 88.3% and the selectivity was 76.2%.

[0060] The final yield of the composite catalyst prepared in Example 3 was 86.3% and the selectivity was 83.1%.

[0061] The final yield of the composite catalyst prepared in Example 4 was 86.3% and the selectivity was 88.5%.

[0062] The final yield of the composite catalyst prepared in Comparative Example 1 was 52.3%, and the selectivity was 33.8%.

[0063] The final yield of the composite catalyst prepared in Comparative Example 2 was 89.1%, and the selectivity was 52.5%.

[0064] The catalyst from Example 1 was filtered, washed, recovered, and reintroduced into the acetonitrile reaction system. The catalyst performance degradation curve during repeated use was recorded. The initial conversion rate of the catalyst was 90.1%, with a selectivity of 95%. The 10th cycle maintained a yield of 89.2%, with a selectivity of 92.8%.

[0065] In summary, this method, through an innovative catalytic system design, achieves efficient, single-step dimerization of hexafluoropropylene under mild conditions (–5–20°C). Its key breakthroughs are: ① The catalyst system utilizes composite components with readily available raw materials and a simple preparation process, ensuring high activity (conversion rate ≥90%) and high selectivity (product purity ≥95%). ② The reaction process, breaking through the traditional limitations of high temperature and high pressure, can be completed at room temperature, significantly reducing energy consumption (saving over 30% compared to traditional processes) and avoiding byproduct formation (trimer content is undetectable). ③ The advantages of industrial application are significant, reducing production costs by approximately 25% through a shortened reaction pathway (single-step dimerization), simplified post-processing, and catalyst recycling (activity retention >90% after 10 cycles).

[0066] This technology not only solves key problems such as catalyst deactivation and low product selectivity in traditional processes, but its "low temperature, high efficiency and green cycle" characteristics are more in line with the needs of modern chemical clean production, and provide technical support for the large-scale application of hexafluoropropylene dimer in high-end materials, electronic chemicals and other fields.

[0067] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a catalyst for preparing D2 structure hexafluoropropylene dimer, characterized in that: The steps include: 1) preparing a porous phase transfer co-catalyst modified with silane groups on its surface; 2) The porous phase transfer co-catalyst obtained in step 1) is dispersed in a solvent and then a mixture of potassium fluoride and hydrofluoric acid is added to obtain a catalyst.

2. The method for preparing a catalyst for preparing D2 structure hexafluoropropylene dimer according to claim 1, characterized in that: The specific steps of step 1) are: 11) immersing the porous support in a phase transfer compound solution, dispersing the porous support evenly, and then drying the porous support to obtain a porous phase transfer co-catalyst loaded with the phase transfer compound; 12) Adding fluorinated organic silane to the porous phase transfer co-catalyst obtained in step 11) to obtain a porous phase transfer co-catalyst with a surface modified with silane groups.

3. The method for preparing a catalyst for preparing D2 structure hexafluoropropylene dimer according to claim 2, characterized in that: The porous carrier is a porous carbon material.

4. The method for preparing a catalyst for preparing D2 structure hexafluoropropylene dimer according to claim 2, characterized in that: The phase transfer compound is 1,2-bis(triethoxysilyl)ethane BTEE. Preferably, the concentration of the phase transfer compound is 0.1-1M, preferably 0.5M.

5. The method for preparing a catalyst for preparing D2 structure hexafluoropropylene dimer according to claim 2, characterized in that: The fluorinated organic silane is a fluorinated alkyl polyether modified polysiloxane; preferably, the mass volume ratio of the porous phase transfer co-catalyst to the fluorinated organic silane is 1 g: (0.1-2) ml; preferably 1 g / 0.5 mL.

6. The method for preparing a catalyst for preparing D2 structure hexafluoropropylene dimer according to claim 1, characterized in that: The specific steps of step 2) are: Under nitrogen protection, potassium fluoride was slowly added to a 40% hydrofluoric acid solution cooled in an ice bath at a molar ratio of KF:HF = 1:1, and stirred continuously until completely dissolved to obtain solution A; Controlling the reaction temperature to <10°C; ultrasonically dispersing a porous phase transfer catalyst having a surface modified silane group in a mixture of water and alcohol, and adding triethylamine to obtain a solution B; preferably, the volume ratio of water to alcohol is 1:6; preferably, the mass volume ratio of the porous phase transfer catalyst having a surface modified silane group to the triethylamine is 1g:(0.1-2)ml; preferably, 1g / 1mL; Subsequently, solution A and solution B are mixed, stirred for 5 hours, and then the solvent is removed by reduced pressure distillation. After washing and vacuum drying, composite catalyst particles are obtained; preferably, the volume ratio of the solution A to the solution B is 1:(0.6-0.8).

7. A catalyst for preparing hexafluoropropylene dimer with D2 structure obtained by the preparation method according to any one of claims 1 to 6.

8. A method for preparing a D2 structure hexafluoropropylene dimer, characterized in that: The method comprises the following steps: adding the catalyst according to claim 7 and an organic solvent into a reactor, cooling the reactor, starting stirring, and introducing hexafluoropropylene into the reactor; after the reaction is completed, opening the reactor, separating the lower layer liquid, and obtaining the target product D2 structure hexafluoropropylene dimer.

9. A method for preparing a D2 structure hexafluoropropylene dimer, characterized in that: The reaction temperature is -5 to 20°C, and the reaction pressure is normal pressure.

10. The method for preparing a D2 structure hexafluoropropylene dimer according to claim 8, wherein: The organic solvents are acetonitrile, diethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether.

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