A nanoscale highly dispersed rhenium-based catalyst for the preparation of perfluorobutylethylene, its preparation method and application

Abstract

This invention belongs to the field of perfluorobutylethylene (PFB) preparation technology, and provides a nanoscale highly dispersed rhenium-based catalyst for the preparation of PFB, its preparation method, and its application. The invention involves calcining a porous oxide to obtain a support; mixing a rhenium source, water, and a pH adjuster to obtain a precursor solution; immersing the support in the precursor solution for electrostatic adsorption to obtain a supported rhenium precursor, which is then calcined to obtain a nanoscale highly dispersed rhenium-based catalyst; the rhenium loading in this rhenium-based catalyst is 0.1~1wt%; the particle size is 0.1~10nm. The catalyst prepared by this method can efficiently activate the bonding sites between perfluorobutyl iodine and ethylene molecules under mild conditions, and its highly dispersed active centers avoid agglomeration and deactivation. It also has the advantages of easy separation and recyclability, reducing separation and purification energy consumption and waste emissions, and effectively suppressing side reactions, making it suitable for continuous industrial production of PFB.

Description

Technical Field

[0001] This invention relates to the field of perfluorobutylethylene preparation technology, and in particular to a nanoscale highly dispersed rhenium-based catalyst for the preparation of perfluorobutylethylene, its preparation method and application. Background Technology

[0002] Perfluorobutylethylene (also known as nonafluoro-1-hexene, CF3-CF2-CF2-CF2-CH=CH2) is an important class of fluorinated olefin compounds with wide applications in functional polymers, surface treatment agents, and specialty fine chemicals. This compound can be used as a polymerization monomer to impart low surface energy, excellent chemical stability, and surface lubricity to polymer materials. It can also be used as a repellent, lubricant, detergent, solvent / refrigerant, or additive in the modification of fluorosilicone resins and fluorosilanes, thus occupying an important position in the fluorochemical and high-performance materials industries.

[0003] Currently, existing literature has explored the synthesis of perfluorobutylethylene to some extent, but significant limitations remain. For example, Szlavik et al. (Org. Lett., 2000) reported the synthesis of perfluorobutylethylene from perfluorobutyl iodide (also known as nonafluoro-4-iodobutane, CF3-CF2-CF2-CF2I) and trimethylsilyl ethylene via a two-step addition and elimination reaction under the action of an initiator, with an overall yield of only 62%. This method not only suffers from the difficulty in obtaining the raw material trimethylsilyl ethylene, but also requires solvents and additives such as tetrahydrofuran, dimethyl sulfoxide, and tetrabutylammonium fluoride, resulting in high separation energy consumption and large emissions of waste gas, wastewater, and solid waste. Furthermore, it is only suitable for small-scale batch operations and cannot meet the needs of continuous industrial production. Rabai et al. (J. Fluor. Chem., 2012) and Coutures et al. (J. Fluor. Chem., 1984) reported an addition-elimination process using perfluorobutyl iodine and ethylene as raw materials, achieving an overall yield of approximately 85%. However, specific process parameters and equipment configuration information were lacking, limiting its practical application. Furthermore, patent WO2002014247A3 discloses the synthesis of perfluorobutylethylene in a large bubble reactor using a strong base and a phase transfer catalyst in the presence of perfluorobutylethyl iodine, achieving a product content of over 95%. However, this process requires a continuous flow of quaternary ammonium salt catalysts, resulting in significant accumulation of waste gas, wastewater, and solid waste. Additionally, the reactor is bulky, requires high energy consumption for insulation, and has poor overall economic and environmental performance.

[0004] In summary, the current synthesis of perfluorobutylene mainly relies on two types of methods: one is a homogeneous catalyst system, the problem of which is that the catalyst is difficult to separate and recover, and the separation process brings additional energy consumption and pollution; the other is a free radical initiator-driven synthesis route, which often requires high temperature, strong solvents and additives, with harsh process conditions and many by-products. These shortcomings seriously restrict the efficient, green and large-scale production of perfluorobutylene.

[0005] Therefore, it is of great significance to develop a continuous synthesis process for preparing perfluorobutylethylene that features easy catalyst separation and recycling, while also ensuring low energy consumption and low emissions of waste gas, wastewater, and solid waste. Summary of the Invention

[0006] In view of this, the present invention provides a nanoscale highly dispersed rhenium-based catalyst for the preparation of perfluorobutylethylene, its preparation method and application, to solve the problems of numerous by-products, difficult catalyst separation, high energy consumption and large emissions of waste gas, wastewater, and solid waste in the existing perfluorobutylethylene synthesis process.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] This invention provides a method for preparing a nanoscale highly dispersed rhenium-based catalyst for the preparation of perfluorobutylethylene, comprising the following steps:

[0009] 1) The porous oxide is calcined to obtain a support;

[0010] 2) Mix the rhenium source, water, and pH adjuster to obtain a precursor solution;

[0011] 3) The support is immersed in the precursor solution for electrostatic adsorption to obtain a supported rhenium precursor, and then the supported rhenium precursor is calcined to obtain a nanoscale highly dispersed rhenium-based catalyst.

[0012] There is no specific order requirement for steps 1) and 2).

[0013] The rhenium loading in the nanoscale highly dispersed rhenium-based catalyst is 0.1~1wt%;

[0014] The nanoscale highly dispersed rhenium-based catalyst has a particle size of 0.1~10 nm.

[0015] Preferably, the porous oxide in step 1) includes one or more of Al2O3, ZrO2 and TiO2; when the porous oxide is Al2O3, the isoelectric point of the support is 8-9; when the porous oxide is ZrO2, the isoelectric point of the support is 6-7; when the porous oxide is TiO2, the isoelectric point of the support is 5-6.

[0016] Preferably, the roasting temperature in step 1) is 400~800℃ and the time is 2~6h.

[0017] Preferably, the rhenium source in step 2) includes ammonium perrhenate and / or perrhenic acid; the pH adjuster includes one or more of nitric acid, formic acid, and acetic acid.

[0018] Preferably, the molar concentration of rhenium in the precursor solution in step 2) is 5~50 mmol / L; and the pH value of the precursor solution is 2~5.

[0019] Preferably, the mass-to-volume ratio of the carrier to the precursor solution in step 3) is 1g:10~50mL.

[0020] Preferably, the electrostatic adsorption time in step 3) is 6~24h; the heating rate of calcination in step 3) is 1~5℃ / min, the temperature is 300~600℃, and the time is 2~6h.

[0021] The present invention also provides a nanoscale highly dispersed rhenium-based catalyst prepared by the above-described method for preparing nanoscale highly dispersed rhenium-based catalysts for the preparation of perfluorobutylethylene.

[0022] This invention also provides an application of the above-mentioned nanoscale highly dispersed rhenium-based catalyst in the preparation of perfluorobutylethylene, wherein the method of application includes the following steps:

[0023] A nanoscale highly dispersed rhenium-based catalyst was mixed with perfluorobutyl iodine and ethylene and reacted to obtain perfluorobutylethylene.

[0024] Preferably, the mass ratio of the nanoscale highly dispersed rhenium-based catalyst to perfluorobutyl iodine is 1:10~100; and the molar ratio of perfluorobutyl iodine to ethylene is 0.5~1:1.

[0025] Preferably, the reaction is carried out in an inert atmosphere, at a temperature of 20-60°C, for a time of 1-6 hours.

[0026] As can be seen from the above technical solution, compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] 1. This invention utilizes an electrostatic adsorption method to prepare a nanoscale highly dispersed rhenium-based catalyst for the preparation of perfluorobutylethylene. Compared with the traditional impregnation method, this method achieves ReO4 production by controlling the pH value of the precursor solution and the charge (isoelectric point) of the support surface. -The directional adsorption of the precursor on the support surface improves the utilization rate and dispersion of the active component, avoiding the uneven distribution and local agglomeration problems that easily occur in the impregnation method. Furthermore, the catalyst obtained in this invention has a Re loading of 0.1~1wt%, offering advantages such as low active center usage and low cost. The active centers of this catalyst are highly dispersed on the support surface, forming nano- or even sub-nanometer-sized rhenium-oxygen species with a particle size of 0.1~10nm, avoiding agglomeration during drying and calcination. Therefore, this catalyst can maintain excellent stability and long-term catalytic activity.

[0028] 2. The nanoscale highly dispersed rhenium-based catalyst for preparing perfluorobutylethylene described in this invention is a solid heterogeneous catalyst. Its active component, rhenium, is firmly supported on the surface of a porous support. Therefore, when using this catalyst to prepare perfluorobutylethylene, physical separation of the catalyst and the reaction system can be achieved, avoiding the problem of catalyst separation and recovery in homogeneous catalysis processes, thereby significantly reducing the energy consumption and waste emissions in subsequent separation and purification.

[0029] 3. The nanoscale highly dispersed rhenium-based catalyst for preparing perfluorobutylethylene described in this invention has highly dispersed active centers and has a strong activation ability for ethylene. Therefore, when using this catalyst and perfluorobutyl iodine and ethylene as raw materials to prepare perfluorobutylethylene, the reaction can be carried out under mild conditions of 20~60℃ without high temperature and high pressure. This not only significantly reduces the risk of the perfluorobutylethylene synthesis process, but also improves the safety and controllability of the reaction.

[0030] 4. The nanoscale highly dispersed rhenium-based catalyst described in this invention achieves a high yield of up to 97% in the preparation of perfluorobutylethylene, with few byproducts, a simple and efficient process, and significant economic and green chemical advantages. It is suitable for continuous and industrial-scale production of perfluorobutylethylene. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0032] Figure 1 This is a transmission electron microscope (TEM) image of the nanoscale highly dispersed rhenium-based catalyst for preparing perfluorobutylethylene prepared in Example 3 of the present invention. Detailed Implementation

[0033] This invention provides a method for preparing a nanoscale highly dispersed rhenium-based catalyst for the preparation of perfluorobutylethylene, comprising the following steps:

[0034] 1) The porous oxide is calcined to obtain a support;

[0035] 2) Mix the rhenium source, water, and pH adjuster to obtain a precursor solution;

[0036] 3) The support is immersed in the precursor solution for electrostatic adsorption to obtain a supported rhenium precursor, and then the supported rhenium precursor is calcined to obtain a nanoscale highly dispersed rhenium-based catalyst.

[0037] There is no specific order requirement for steps 1) and 2).

[0038] The rhenium loading in the nanoscale highly dispersed rhenium-based catalyst is 0.1~1wt%, preferably 0.2~0.9wt%, more preferably 0.3~0.8wt%, and even more preferably 0.5~0.6wt%.

[0039] The nanoscale highly dispersed rhenium-based catalyst has a particle size of 0.1~10nm, preferably 0.5~7.6nm, more preferably 1.3~5.6nm, and even more preferably 3.5~4.7nm.

[0040] In this invention, the porous oxide in step 1) preferably includes one or more of Al2O3, ZrO2 and TiO2; when the porous oxide is Al2O3, the isoelectric point of the support is 8-9, preferably 8.5; when the porous oxide is ZrO2, the isoelectric point of the support is 6-7, preferably 6.3; when the porous oxide is TiO2, the isoelectric point of the support is 5-6, preferably 5.8.

[0041] In this invention, the pre-roasting operation is preferably included before the roasting in step 1); the pre-roasting temperature is preferably 400~800℃, more preferably 450~700℃, and even more preferably 500~600℃; the pre-roasting time is preferably 1~6h, more preferably 2~5h, and even more preferably 3~4h.

[0042] In this invention, the roasting temperature in step 1) is 400~800℃, preferably 500~750℃, more preferably 550~700℃, and even more preferably 600~650℃; the roasting time is 2~6h, preferably 3~5.5h, more preferably 3.5~4.5h, and even more preferably 4h.

[0043] In this invention, after the carrier described in step 1) is placed in the air, its surface will adsorb substances such as H2O, CO2 or volatile organic compounds from the air. This will affect its adsorption of active substances during the impregnation process, especially when impregnating with a low loading, this effect will be very obvious. Therefore, when preparing the catalyst by electrostatic adsorption, the water, carbonates and organic impurities adsorbed on the surface of the carrier will be removed in advance by pre-calcination and / or calcination treatment, restoring a clean hydroxyl environment on the surface of the carrier, thereby ensuring that the active metal components can be highly dispersed and uniformly anchored on the surface of the carrier.

[0044] In this invention, the rhenium source in step 2) preferably includes ammonium perrhenate and / or perrhenic acid; the pH adjuster preferably includes one or more of nitric acid, formic acid, and acetic acid.

[0045] In this invention, the molar concentration of rhenium in the precursor solution in step 2) is 5~50 mmol / L, preferably 5.57~49.7 mmol / L, more preferably 9.69~33.84 mmol / L, and even more preferably 11.2~17.9 mmol / L; the pH value of the precursor solution is 2~5, preferably 2.5~4.5, more preferably 3~4, and even more preferably 3.5.

[0046] In this invention, the mass-to-volume ratio of the carrier to the precursor solution in step 3) is 1g:10~50mL, preferably 1g:15~40mL, more preferably 1g:20~35mL, and even more preferably 1g:24~30mL.

[0047] In this invention, the electrostatic adsorption time in step 3) is 6~24h, preferably 7~20h, more preferably 7.5~15h, and more preferably 8h.

[0048] In this invention, the preferred principle of electrostatic adsorption in step 3) is as follows: when the support is placed in a solution, if the pH value of the solution is lower than the isoelectric point of the support and the surface of the support is positively charged, then the support easily adsorbs anions in the solution; conversely, if the pH value of the solution is higher than the isoelectric point of the support and the surface of the support is negatively charged, then the support easily adsorbs cations in the solution. In this invention, Re in the precursor solution exists as perrhenate anions. Therefore, by adjusting the pH value of the precursor solution to be lower than the isoelectric point of the corresponding support, electrostatic adsorption can be achieved. The advantage of preparing catalysts by electrostatic adsorption is that, through the anchoring effect of positive and negative charges, Re anions can be firmly adsorbed onto the surface of the support, thereby achieving high dispersibility.

[0049] In this invention, step 3) preferably includes filtration, washing, and drying operations before calcination; the washing solution preferably includes water and / or anhydrous ethanol; the drying temperature is preferably 80~120℃, more preferably 90~110℃, and even more preferably 100℃; the drying time is preferably 8~15h, more preferably 10~14h, and even more preferably 12h.

[0050] In this invention, the heating rate of calcination in step 3) is 1~5℃ / min, preferably 1.5~4.5℃ / min, more preferably 2~4℃ / min, and even more preferably 3~3.5℃ / min; the calcination temperature is 300~600℃, preferably 350~580℃, more preferably 400~550℃, and even more preferably 450~500℃; the calcination time is 2~6h, preferably 2.5~5.5h, more preferably 3~5h, and even more preferably 3.5~4h.

[0051] The present invention also provides a nanoscale highly dispersed rhenium-based catalyst prepared by the above-described method for preparing nanoscale highly dispersed rhenium-based catalysts for the preparation of perfluorobutylethylene.

[0052] This invention also provides an application of the above-mentioned nanoscale highly dispersed rhenium-based catalyst in the preparation of perfluorobutylethylene, wherein the method of application includes the following steps:

[0053] A nanoscale highly dispersed rhenium-based catalyst was mixed with perfluorobutyl iodine and ethylene and reacted to obtain perfluorobutylethylene.

[0054] In this invention, the mixing is preferably carried out by first mixing a nanoscale highly dispersed rhenium-based catalyst and perfluorobutyl iodine, and then adding ethylene under an inert atmosphere.

[0055] In this invention, the mass ratio of the nanoscale highly dispersed rhenium-based catalyst to perfluorobutyl iodine is 1:10~100, preferably 1:20~90, more preferably 1:30~60, and even more preferably 1:40~50; the molar ratio of perfluorobutyl iodine to ethylene is 0.5~1:1, preferably 0.6~0.9:1, and even more preferably 0.7~0.8:1.

[0056] In this invention, the reaction atmosphere is an inert atmosphere, and the gas in the inert atmosphere is preferably one or more of nitrogen, argon and helium; the reaction temperature is 20~60℃, preferably 30~55℃, more preferably 35~50℃, and even more preferably 40~45℃; the reaction time is 1~6h, preferably 1.5~5h, more preferably 2~4.5h, and even more preferably 3~4h.

[0057] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0058] Example 1

[0059] Preparation of nanoscale highly dispersed rhenium-based catalysts

[0060] 5.00 g of γ-Al₂O₃ was calcined at 500 °C for 4 h and then cooled for later use. Simultaneously, 0.45 g of ammonium perrhenate (NH₄ReO₄) was dissolved in 150 mL of deionized water, and the pH of the solution was adjusted to 3.5 with 0.01 mol / L dilute nitric acid to obtain a precursor solution (the molar concentration of rhenium in the precursor solution was 11.2 mmol / L). The calcined γ-Al₂O₃ (isoelectric point 8) was then... 5) Mix with the precursor solution, stir magnetically for 8 hours, then filter and separate, wash three times with deionized water, then wash three times with anhydrous ethanol, and then dry at 80℃ for 12 hours to obtain the supported rhenium precursor. Finally, heat the supported rhenium precursor to 450℃ in air at a heating rate of 2℃ / min and hold for 4 hours to obtain a nanoscale highly dispersed Re2O7 / γ-Al2O3 catalyst with an average particle size of 5.6nm, denoted as catalyst A.

[0061] Example 2

[0062] Preparation of nanoscale highly dispersed rhenium-based catalysts

[0063] 5.00 g of ZrO2 was calcined at 600 °C for 4 h and then cooled for later use. Simultaneously, 0.85 g of perrhenic acid (HReO4) was dissolved in 100 mL of deionized water, and the pH was adjusted to 2.5 with 0.1 mol / L dilute nitric acid to obtain a precursor solution (the molar concentration of rhenium in the precursor solution was 33.84 mmol / L). The calcined ZrO2 (isoelectric point 6.3) and... The precursor solutions were mixed and magnetically stirred for 8 hours, then filtered and separated. The mixture was washed three times with deionized water, followed by three times with anhydrous ethanol, and then dried at 100°C for 12 hours to obtain a supported rhenium precursor. Finally, the supported rhenium precursor was heated to 350°C in air at a heating rate of 3°C / min and held for 2 hours to obtain a nanoscale highly dispersed Re2O7 / ZrO2 catalyst with an average particle size of 3.5 nm, denoted as catalyst B.

[0064] Example 3

[0065] Preparation of nanoscale highly dispersed rhenium-based catalysts

[0066] 5.00 g of γ-Al₂O₃ was pre-calcined at 600 °C for 2 h, then calcined at 800 °C for 4 h, and cooled for later use. Simultaneously, 1.00 g of ammonium perrhenate (NH₄ReO₄) was dissolved in 75 mL of deionized water, and the pH of the solution was adjusted to 3.0 with 0.01 mol / L dilute nitric acid to obtain a precursor solution (the molar concentration of rhenium in the precursor solution was 49.7 mmol / L). The calcined γ-Al₂O₃ ( The rhenium precursor solution (with an isoelectric point of 8.5) was mixed with the precursor solution and magnetically stirred for 8 hours. Then, it was filtered and separated, washed three times with deionized water, followed by three times with anhydrous ethanol, and then dried at 100°C for 12 hours to obtain the supported rhenium precursor. Finally, the supported rhenium precursor was heated to 400°C in air at a heating rate of 1°C / min and held for 3 hours to obtain a nanoscale highly dispersed Re2O7 / γ-Al2O3 catalyst with an average particle size of 1.3 nm, denoted as catalyst C.

[0067] The distribution of active sites of catalyst C prepared in Example 3 was tested using a JEOL JEM-2100 transmission electron microscope. The specific testing procedure was as follows: catalyst C (1 mg) was dispersed in anhydrous ethanol (1 mL) and sonicated for 10 min under a 100 W ultrasonic probe (20 Hz). Then, it was dropped onto a 300-mesh carbon-coated copper grid and allowed to dry naturally for 12 h. Afterwards, images were acquired using a 200 kV transmission electron microscope, and the dispersion state and particle size distribution of Re species in the catalyst were observed using high-angle annular dark-field scanning (HAADF-STEM) mode. The results are as follows: Figure 1 As shown, from Figure 1 As can be seen, a large number of dark-colored nanoparticles are uniformly distributed on the catalyst surface, with particle sizes mainly concentrated in the range of 0.5~2 nm and an average particle size of 1.3 nm. No obvious agglomeration or large particle deposition was observed, indicating that rhenium species are highly dispersed on the support surface. This result shows that the electrostatic adsorption method used in this invention can achieve directional adsorption and uniform anchoring of Re species by controlling the solution pH and the surface charge of the support, thereby effectively avoiding the metal agglomeration phenomenon commonly seen in traditional impregnation methods. The highly dispersed nanoscale active centers significantly improve the utilization rate and reaction stability of rhenium, providing a structural basis for the efficient conversion of perfluorobutyl iodine and ethylene under mild conditions, and verifying the feasibility and superiority of the preparation method of this invention.

[0068] Example 4

[0069] Preparation of nanoscale highly dispersed rhenium-based catalysts

[0070] 5.00 g of TiO2 was pre-calcined at 700 °C for 5 h, then calcined at 700 °C for 4 h, and cooled for later use. Simultaneously, 0.07 g of perrhenic acid (HReO4) was dissolved in 50 mL of deionized water, and the pH of the solution was adjusted to 4.0 with 0.01 mol / L dilute nitric acid to obtain a precursor solution (the molar concentration of rhenium in the precursor solution was 5.57 mmol / L). The calcined TiO2 (isoelectric point...) The rhenium precursor (5.8) was mixed with the precursor solution and magnetically stirred for 8 hours. Then, it was filtered and separated, washed three times with deionized water, followed by three times with anhydrous ethanol, and then dried at 100°C for 12 hours to obtain the supported rhenium precursor. Finally, the supported rhenium precursor was heated to 500°C in air at a heating rate of 4°C / min and held for 5 hours to obtain a nanoscale highly dispersed Re2O7 / TiO2 catalyst with an average particle size of 0.5 nm, denoted as catalyst D.

[0071] Example 5

[0072] Preparation of nanoscale highly dispersed rhenium-based catalysts

[0073] 5.00 g of TiO2 was pre-calcined at 400 °C for 6 h, then calcined at 400 °C for 4 h, and cooled for later use. Simultaneously, 0.90 g of perrhenic acid (HReO4) was dissolved in 200 mL of deionized water, and the pH of the solution was adjusted to 2.0 with 0.1 mol / L dilute nitric acid to obtain a precursor solution (the molar concentration of rhenium in the precursor solution was 17.9 mmol / L). The calcined TiO2 (isoelectric point...) The rhenium precursor solution (5.8) was mixed with the precursor solution and magnetically stirred for 8 hours. Then, it was filtered and separated, washed three times with deionized water, followed by three times with anhydrous ethanol, and then dried at 80°C for 12 hours to obtain the supported rhenium precursor. Finally, the supported rhenium precursor was heated to 600°C in air at a heating rate of 5°C / min and held for 6 hours to obtain a nanoscale highly dispersed Re2O7 / TiO2 catalyst with an average particle size of 7.6 nm, denoted as catalyst E.

[0074] Example 6

[0075] Preparation of nanoscale highly dispersed rhenium-based catalysts

[0076] 5.00 g of ZrO2 was pre-calcined at 800 °C for 4 h, then calcined at 500 °C for 4 h, and cooled for later use. Simultaneously, 0.65 g of ammonium perrhenate (NH4ReO4) was dissolved in 120 mL of deionized water, and the pH of the solution was adjusted to 5.0 with 0.01 mol / L dilute nitric acid to obtain a precursor solution (the molar concentration of rhenium in the precursor solution was 9.69 mmol / L). The calcined ZrO2 (etc.) The rhenium precursor (with an electrical point of 6.3) was mixed with the precursor solution and magnetically stirred for 8 hours. Then, it was filtered and separated, washed three times with deionized water, followed by three times with anhydrous ethanol, and then dried at 120°C for 12 hours to obtain the supported rhenium precursor. Finally, the supported rhenium precursor was heated to 300°C in air at a heating rate of 3°C / min and held for 3 hours to obtain a nanoscale highly dispersed Re2O7 / ZrO2 catalyst with an average particle size of 4.7 nm, denoted as catalyst F.

[0077] The Re content of the catalysts prepared in Examples 1-6 above was tested. The Re content in the catalysts was measured using inductively coupled plasma optical emission spectrometry (ICP-OES) on an Agilent 5110 instrument. The specific steps are as follows:

[0078] Accurately weigh 50.00 mg of catalyst and place it in a 10 mL polytetrafluoroethylene (PTFE) digestion vessel. Add 5 mL of aqua regia and 1 mL of 30% hydrogen peroxide. Then, microwave digest at 100 °C until the catalyst is completely dissolved and a clear solution is formed. After cooling to room temperature, transfer the solution to a volumetric flask and dilute to 50.0 mL with deionized water to obtain the test solution. Subsequently, using 1000 mg / L standard Re solution, prepare standard solutions with mass concentrations of 1, 2, 5, 10, and 20 mg / L through serial dilution. The blank solution is the same acid solution used for sample dissolution (i.e., the aforementioned mixture of aqua regia and hydrogen peroxide) and is used for ICP-OES testing, with the influence of the method blank subtracted during the test. A calibration curve was established by selecting appropriate Re analysis lines (with the concentration of the standard solution on the x-axis and the corresponding instrument response value on the y-axis). The prepared test solution was then quantitatively measured based on this curve. The Re concentration corresponding to the test solution was found from the calibration curve based on the instrument response value of the test solution. Finally, the Re content in the catalyst was calculated using the following formula. The results are shown in Table 1.

[0079]

[0080] In the formula, w(Re,%) is the Re content in the sample, and C meas The Re concentration (mg / L) of the sample solution, C blank, where Re is the concentration of the blank solution (mg / L), V is the final volume (L), f is the dilution factor, and m is the sample mass (g).

[0081] Table 1 Re content in the catalyst

[0082]

[0083] As shown in Table 1, the Re-based catalysts prepared by electrostatic adsorption in this invention have Re contents ranging from 0.1% to 1%. This not only reduces the cost of using the precious metal Re, but also avoids the problem of uneven metal distribution or excessive deposition common in traditional impregnation methods due to the high dispersion of Re on the support surface (particle size of about 0.5 to 5 nm). It can maintain excellent catalytic activity and stability even at low loading and avoid agglomeration and deactivation.

[0084] Example 7

[0085] Preparation of perfluorobutylethylene

[0086] 1.00 g of catalyst A and 30 g of perfluorobutyl iodine were added to a 300 mL high-pressure reactor. After the air in the reactor was purged with N2, ethylene was introduced into the reactor. The molar ratio of perfluorobutyl iodine to ethylene was 0.9. The reactor was then sealed and heated to 30 °C for 3 h to obtain perfluorobutylethylene.

[0087] Example 8

[0088] Preparation of perfluorobutylethylene

[0089] 1.00 g of catalyst A and 50 g of perfluorobutyl iodine were added to a 300 mL high-pressure reactor. After the air in the reactor was purged with N2, ethylene was introduced into the reactor. The molar ratio of perfluorobutyl iodine to ethylene was 0.6. The reactor was then sealed and heated to 60 °C for 4 h to obtain perfluorobutylethylene.

[0090] Example 9

[0091] Preparation of perfluorobutylethylene

[0092] 1.00 g of catalyst A and 60 g of perfluorobutyl iodine were added to a 300 mL high-pressure reactor. After the air in the reactor was purged with N2, ethylene was introduced into the reactor. The molar ratio of perfluorobutyl iodine to ethylene was 0.8. The reactor was then sealed and heated to 50 °C for 6 h to obtain perfluorobutylethylene.

[0093] Example 10

[0094] Preparation of perfluorobutylethylene

[0095] 1.00 g of catalyst A and 60 g of perfluorobutyl iodine were added to a 300 mL high-pressure reactor. After the air in the reactor was purged with N2, ethylene was introduced into the reactor. The molar ratio of perfluorobutyl iodine to ethylene was 0.7. The reactor was then sealed and heated to 40 °C for 2 h to obtain perfluorobutylethylene.

[0096] Example 11

[0097] Preparation of perfluorobutylethylene

[0098] 1.00 g of catalyst A and 40 g of perfluorobutyl iodine were added to a 300 mL high-pressure reactor. After the air in the reactor was purged with N2, ethylene was introduced into the reactor. The molar ratio of perfluorobutyl iodine to ethylene was 0.5. The reactor was then sealed and heated to 20 °C for 5 h to obtain perfluorobutylethylene.

[0099] Example 12

[0100] Preparation of perfluorobutylethylene

[0101] 1.00 g of catalyst A and 20 g of perfluorobutyl iodine were added to a 300 mL high-pressure reactor. After the air in the reactor was purged with N2, ethylene was introduced into the reactor. The molar ratio of perfluorobutyl iodine to ethylene was 0.7. The reactor was then sealed and heated to 30 °C for 2 h to obtain perfluorobutylethylene.

[0102] Example 13

[0103] Preparation of perfluorobutylethylene

[0104] 1.00 g of catalyst A and 10 g of perfluorobutyl iodine were added to a 300 mL high-pressure reactor. After the air in the reactor was purged with N2, ethylene was introduced into the reactor. The molar ratio of perfluorobutyl iodine to ethylene was 0.9. The reactor was then sealed and heated to 40 °C for 3 h to obtain perfluorobutylethylene.

[0105] Example 14

[0106] Preparation of perfluorobutylethylene

[0107] 1.00 g of catalyst A and 90 g of perfluorobutyl iodine were added to a 300 mL high-pressure reactor. After the air in the reactor was purged with N2, ethylene was introduced into the reactor. The molar ratio of perfluorobutyl iodine to ethylene was 1.0. The reactor was then sealed and heated to 50 °C for 4 h to obtain perfluorobutylethylene.

[0108] Example 15

[0109] Preparation of perfluorobutylethylene

[0110] 1.00 g of catalyst A and 100 g of perfluorobutyl iodine were added to a 300 mL high-pressure reactor. After the air in the reactor was purged with N2, ethylene was introduced into the reactor. The molar ratio of perfluorobutyl iodine to ethylene was 0.8. The reactor was then sealed and heated to 60 °C for 1 h to obtain perfluorobutylethylene.

[0111] Comparative Example 1

[0112] Preparation of perfluorobutylethylene

[0113] The only difference between Comparative Example 1 and Example 9 is that no catalyst is added.

[0114] Comparative Example 2

[0115] Preparation of perfluorobutylethylene

[0116] The only difference between Comparative Example 2 and Example 9 is that the reaction temperature is 90°C.

[0117] Comparative Example 3

[0118] Preparation of perfluorobutylethylene

[0119] The only difference between Comparative Example 3 and Example 9 is that the reaction temperature is 0°C.

[0120] Comparative Example 4

[0121] Preparation of perfluorobutylethylene

[0122] The only difference between Comparative Example 4 and Example 9 is that the catalyst is a Re2O7 / Al2O3 catalyst, which is prepared by an equal-volume impregnation method. Specifically, 5.00 g of γ-Al2O3 is calcined at 500°C for 4 hours in air, and the resulting support is cooled for later use. The pore volume of the support is pre-measured to be 0.85 mL / g using nitrogen adsorption. 0.036 g of ammonium perrhenate is weighed and dissolved in 4.25 mL of deionized water without pH adjustment or ionic strength control to obtain the impregnation solution. The impregnation solution is added dropwise to the above support under stirring, mixing thoroughly until completely wetted (equal-volume impregnation), and allowed to stand for 2 hours for aging. Subsequently, it is dried at 110°C for 12 hours, and after drying, it is subjected to an air atmosphere at 5°C·min. -1 The temperature was raised to 400℃, held for 3 hours, and then cooled to obtain the Re2O7 / γ-Al2O3 catalyst, which was designated as the comparative catalyst C-IM.

[0123] The perfluorobutylethylene prepared in Examples 7-15 and Comparative Examples 1-4 was qualitatively and quantitatively analyzed using gas chromatography-mass spectrometry (GC-MS). The GC-MS system was equipped with an FID detector and an MS detector, and the chromatographic column was an Agilent GC-Pro column with a length of 50 m. The conversion rates of perfluorobutyl iodine and the selectivity of perfluorobutylethylene in Examples 7-15 and Comparative Examples 1-4 are calculated using the following formulas:

[0124] Conversion rate of perfluorobutyl iodide = [n(residual amount of perfluorobutyl iodide) / n(input amount of perfluorobutyl iodide)] × 100%;

[0125] Selectivity of perfluorobutylethylene = {n(perfluorobutylethylene) / [n(perfluorobutyl iodine input) - n(perfluorobutyl iodine residue)]} × 100%;

[0126] In the formula, n is the amount of substance, and the results are shown in Table 2.

[0127] Table 2. Conversion rate of perfluorobutyl iodine and selectivity and yield of perfluorobutylethylene

[0128]

[0129] As shown in Table 2, under the action of the nanoscale highly dispersed rhenium-based catalyst described in this invention, the conversion rate of perfluorobutyl iodine exceeds 90%, and the selectivity of perfluorobutylethylene exceeds 90%. Furthermore, comparing the detection data in Examples 7-15 and Comparative Examples 1-4, it can be seen that the reaction temperature and the type of catalyst both affect the conversion rate of perfluorobutyl iodine and the selectivity and yield of perfluorobutylethylene.

[0130] In Comparative Example 1, the conversion rate of perfluorobutyl iodine was only 2%, and the selectivity of the perfluorobutylethylene product was only 63%. In contrast, the conversion rates of perfluorobutyl iodine and the selectivity of perfluorobutylethylene in Examples 7-15 both exceeded 90%. This indicates that it is difficult to obtain the perfluorobutylethylene product without the use of a catalyst.

[0131] In Comparative Example 2, the conversion rate of perfluorobutyl iodine was 100%, and the selectivity of the perfluorobutylethylene product was 74%, indicating that when the reaction temperature is higher than 60℃, the reactants will react into other byproducts.

[0132] In Comparative Example 3, the conversion rate of perfluorobutyl iodine was only 13%, indicating that when the reaction temperature is below 20℃, the catalyst activity is low and the reaction raw materials cannot be effectively converted.

[0133] In Comparative Example 4, the catalyst prepared using the traditional impregnation method was used to prepare perfluorobutylethylene. The final conversion rate of perfluorobutyl iodine was 12%, and the selectivity of the perfluorobutylethylene product was 39%. In the traditional impregnation method, the adsorption of the metal precursor mainly relies on capillary wetting and physical adsorption. The high ionic strength and uncontrollable pH of the solution easily lead to uneven distribution of metal species on the support surface or migration and aggregation during drying and calcination, resulting in larger particles and low utilization of active sites. In contrast, this invention achieves directional electrostatic adsorption of Re ions on the support surface by adjusting the solution pH to give the support surface an opposite charge to the rhenium precursor. This allows the metal species to be uniformly anchored to the surface hydroxyl sites at the molecular level. This method can achieve precise control of the metal loading during the adsorption stage, significantly improving the dispersion of active centers. The particle size of the obtained Re species can be stably maintained in the range of 0.1~10 nm, and the structure remains stable during calcination without aggregation. Therefore, the catalyst prepared by this invention exhibits higher activity and selectivity under the same metal loading, and has comprehensive advantages such as low active center usage, high stability and excellent long-term recycling performance, which can significantly improve the conversion rate of perfluorobutyl iodine and the selectivity and yield of perfluorobutylethylene products.

[0134] In summary, this invention provides a nanoscale highly dispersed rhenium-based catalyst prepared by electrostatic adsorption, achieving the efficient conversion of perfluorobutyl iodine and ethylene to perfluorobutylethylene. The method of this invention anchors Re species in a highly dispersed manner on the surface of a porous oxide support, forming stable nanoscale or even sub-nanometer-scale active centers. These centers can efficiently activate the molecular bonding sites of perfluorobutyl iodine and ethylene under mild conditions, thereby achieving selective conversion via a non-radical pathway. Simultaneously, the highly dispersed active centers of the catalyst prevent agglomeration and deactivation, ensuring the long-term stability of the reaction process and effectively suppressing side reactions. By optimizing the Re loading, feed ratio, and reaction temperature, this invention achieves a high yield of up to 97% and a high selectivity of up to 98% for the target product, perfluorobutylethylene. The process described in this invention not only overcomes the difficulties in separation and severe waste emissions associated with homogeneous catalysis but also avoids the harsh reaction conditions and byproduct accumulation inherent in radical routes, demonstrating broad application prospects in the green and efficient synthesis of perfluorobutylethylene.

[0135] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. The application of a nanoscale highly dispersed rhenium-based catalyst in the preparation of perfluorobutylethylene, characterized in that, The method of application includes the following steps: A nanoscale highly dispersed rhenium-based catalyst was mixed with perfluorobutyl iodine and ethylene and reacted to obtain perfluorobutylethylene. The mass ratio of the nanoscale highly dispersed rhenium-based catalyst to perfluorobutyl iodine is 1:10~100; The molar ratio of perfluorobutyl iodine to ethylene is 0.5~1:1; The reaction is carried out in an inert atmosphere, at a temperature of 20-60°C, for a time of 1-6 hours. The preparation method of the nanoscale highly dispersed rhenium-based catalyst includes the following steps: 1) The porous oxide is calcined to obtain a support; 2) Mix the rhenium source, water, and pH adjuster to obtain a precursor solution; 3) The support is immersed in the precursor solution for electrostatic adsorption to obtain a supported rhenium precursor, and then the supported rhenium precursor is calcined to obtain a nanoscale highly dispersed rhenium-based catalyst. There is no specific order requirement for steps 1) and 2). The rhenium loading in the nanoscale highly dispersed rhenium-based catalyst is 0.1~1wt%; The nanoscale highly dispersed rhenium-based catalyst has a particle size of 0.1~10 nm.

2. The application of the nanoscale highly dispersed rhenium-based catalyst according to claim 1 in the preparation of perfluorobutylethylene, characterized in that, The porous oxide mentioned in step 1) includes one or more of Al2O3, ZrO2 and TiO2; When the porous oxide is Al2O3, the isoelectric point of the support is 8-9; When the porous oxide is ZrO2, the isoelectric point of the support is 6~7; When the porous oxide is TiO2, the isoelectric point of the support is 5 to 6.

3. The application of the nanoscale highly dispersed rhenium-based catalyst according to claim 2 in the preparation of perfluorobutylethylene, characterized in that, The roasting temperature in step 1) is 400~800℃ and the time is 2~6h.

4. The application of a nanoscale highly dispersed rhenium-based catalyst according to any one of claims 1 to 3 in the preparation of perfluorobutylethylene, characterized in that, The rhenium source mentioned in step 2) includes ammonium perrhenate and / or perrhenic acid; The pH adjuster includes one or more of nitric acid, formic acid, and acetic acid.

5. The application of the nanoscale highly dispersed rhenium-based catalyst according to claim 4 in the preparation of perfluorobutylethylene, characterized in that, The molar concentration of rhenium in the precursor solution described in step 2) is 5~50 mmol / L; The pH value of the precursor solution is 2-5.

6. The application of the nanoscale highly dispersed rhenium-based catalyst according to claim 5 in the preparation of perfluorobutylethylene, characterized in that, The mass-to-volume ratio of the carrier to the precursor solution in step 3) is 1g:10~50mL.

7. The application of the nanoscale highly dispersed rhenium-based catalyst according to claim 6 in the preparation of perfluorobutylethylene, characterized in that, The electrostatic adsorption time described in step 3) is 6~24h; The calcination process described in step 3) involves a heating rate of 1~5℃ / min, a temperature of 300~600℃, and a time of 2~6h.

Images