Palladium-potassium / nano-iron fluoride catalyst and its use for the synthesis of dodecafluorodihexane

Abstract

This invention discloses a palladium-potassium / nano-iron fluoride catalyst and its application in the synthesis of dodecylfluorodihydrohexane, aiming to solve the technical problems of cumbersome preparation processes, uneven dispersion of active components, and difficulty in controlling the preparation process in existing catalysts. The catalyst uses nano-iron fluoride as a support and palladium and potassium as active components. This catalyst exhibits excellent catalytic activity under relatively low reaction temperature and pressure conditions, and can efficiently catalyze the hydrogenation reaction of hexafluoropropylene dimer to produce dodecylfluorodihydrohexane, providing reliable technical support for the industrial-scale and efficient preparation of dodecylfluorodihydrohexane.

Description

Technical Field

[0001] This invention belongs to the field of compound preparation, specifically relating to palladium-potassium / nano-iron fluoride catalysts and their application in the synthesis of dodecafluorodihydrohexane. Background Technology

[0002] Dodecafluorodihydrohexane ((CF3)2CF–CHF–CHF–CF3) is an important intermediate in a class of fluorine-containing fine chemicals. This compound has a high fluorine content (containing 12 fluorine atoms), and the strong inductive effect of fluorine atoms significantly improves its physicochemical properties, giving it excellent characteristics such as high chemical stability, high hydrophobicity, low surface energy, and weak polarity. Simultaneously, its ozone depletion potential (ODP) is 0, making it a promising candidate for use as a refrigerant in next-generation electronic devices.

[0003] Currently, the synthesis of dodecafluorodihydrohexane mainly relies on the catalytic hydrogenation of hexafluoropropylene dimer ((CF3)2CF–CF=CF–CF3) as the core route, and related research often employs noble metal catalysts. For example, patent CN201010519726.8 discloses a hydrogenation catalyst with Pd as the main active component, one or more of La, Ce, Cu, Zn, or Ni as promoters, and activated carbon as the support, which can achieve high feed conversion and target product selectivity at relatively low temperatures and pressures. Patent CN202311458020.9 reports a method for preparing dodecafluorodihydrohexane by catalytic hydrogenation of hexafluoropropylene dimer, in which the catalyst uses Pd and Rh as dual active metals and is prepared by impregnating resin-based spherical activated carbon with organic ligands. Although it can achieve high conversion and selectivity, the catalyst preparation process is relatively complex. Patent CN109652819B discloses a method for preparing perfluorohexane, in which the catalyst used in the synthesis of dodecafluorodihydrohexane uses Rh or Rh / Pd as the main active component and Ni and / or Zn as auxiliary agents, supported on an activated carbon support, and the hydrogenation reaction has high conversion and selectivity. In addition, related literature (Journal of Process Engineering, 2024, 24 (2): 248; Catalysis Science & Technology, 2025, 15, 2919; Molecular Catalysis, 2024, 552: 113652) also reported that Pd is used as the active component, and strategies such as support structure regulation or auxiliary agent modification are used to improve the conversion and selectivity of the reaction.

[0004] Although existing technologies have been extensively studied in this hydrogenation system, problems such as insufficient selectivity or poor stability of the target product still exist, making it difficult to meet the needs of continuous and stable industrial production. Summary of the Invention

[0005] In view of the defects or deficiencies of the prior art, the present invention provides a palladium-potassium / nano-iron fluoride catalyst.

[0006] Therefore, the palladium-potassium / nano-iron fluoride catalyst provided by the present invention includes a support and an active component, wherein the support is nano-iron fluoride and the active component is palladium and potassium.

[0007] An alternative approach is to use the mass percentage loading of the active component as a reference, which is 0.1% to 20% based on the carrier mass.

[0008] An alternative is that the molar ratio of palladium to potassium is 1:(1~20).

[0009] An optional approach is that the catalyst preparation method includes: impregnating nano-sized iron fluoride in an aqueous solution containing palladium and potassium salts, then collecting the solid, and sequentially drying, calcining, and reducing the solid to obtain a palladium-potassium / iron fluoride catalyst; the calcination temperature is 200–350°C; the reduction is performed using hydrogen reduction or wet reduction; the hydrogen reduction includes a reduction reaction carried out at 150–300°C in the presence of hydrogen; the wet reduction includes a reduction reaction carried out at 20–100°C in the presence of a reducing agent, wherein the reducing agent is selected from one or more combinations of sodium borohydride, hydrazine hydrate, hydrogen, and alcohols.

[0010] Alternatively, the palladium salt may be one or any combination of palladium chloride, palladium nitrate, and palladium acetate, and the potassium salt may be one or any combination of potassium chloride and potassium nitrate.

[0011] Alternatively, the impregnation method may be one or a combination of equal volume impregnation, excessive impregnation, and precipitation impregnation.

[0012] This invention also provides the application of the above-mentioned catalyst in the hydrogenation of hexafluoropropylene dimer to synthesize dodecafluorodihydrohexane. Optionally, the molar ratio of hydrogen to hexafluoropropylene dimer is (2–8):1. The synthesis reaction temperature is 50–250°C, and the feed space velocity is 5–100 h⁻¹. -1 The amount of catalyst used in the synthesis process is 2-4g.

[0013] The catalyst preparation process of this invention is safe and efficient, solving the problems of complex catalyst preparation processes, uneven dispersion of active components, and uncontrollable preparation processes in the prior art.

[0014] This invention provides a catalyst for the hydrogenation synthesis of dodecyl dihydrohexane using hexafluoropropylene dimer as a raw material. The catalyst can operate continuously for 100 hours, maintaining a hexafluoropropylene dimer conversion rate of over 90% and a dodecyl dihydrohexane selectivity of over 95%. Attached Figure Description

[0015] Figure 1 This is the GC-MS spectrum of the reactant hexafluoropropylene dimer.

[0016] Figure 2 This is the GC-MS spectrum of the product, dodecafluorodihydrohexane. Detailed Implementation

[0017] Unless otherwise specified, the terminology used herein is based on the understanding of those skilled in the art. It should be noted that, based on the carrier preparation scheme of this invention, those skilled in the art can optimize the selection of, but not limited to, specific reactants, the ratio of reactants in each step, temperature and duration, drying temperature and calcination temperature involved in the method of this invention to achieve the relevant effects of the carrier of this invention.

[0018] The nano-iron fluoride described in this invention is the nano-iron fluoride disclosed in patent ZL201611178343.2, and the preparation method of the nano-iron fluoride disclosed therein is as follows:

[0019] (1) Mix the iron source, complexing agent and polyol, and reflux at 30℃~80℃ for more than 6 hours to obtain reaction solution A; the iron source is one or any combination of ferric nitrate, ferric chloride, ferric sulfate and ferric acetate; the polyol is one or any combination of ethylene glycol, diethylene glycol, 1,3-propanediol, 1,2-propanediol and glycerol; the complexing agent is one or any combination of polyethylene glycol, polyvinylpyrrolidone, cyclodextrin, citric acid, cyclodextrin, polyvinyl alcohol and ethylene oxide, and the mass ratio of iron source to complexing agent is 1:0.5~10; (2) Under stirring, the fluorinating reagent is added to the reaction solution A for fluorination treatment. After the addition is complete, the mixture is refluxed and stirred at 140℃~200℃ for more than 6 hours to obtain a suspension. The fluorinating reagent is one of the components of hydrogen fluoride and ammonium fluoride aqueous solution. The concentration of the fluorinating reagent is 20wt.%~90wt.%, and the molar ratio of the fluorinating reagent to the iron source is 3~6:1. (3) After the suspension is allowed to stand at 100℃~160℃ for 24 hours, it is washed and filtered to obtain a solid. (4) Finally, the solid was calcined at 200℃~350℃ for more than 4 hours to obtain nano-iron fluoride.

[0020] The catalyst performance testing method in the following examples is as follows: 3g of the catalyst described in this invention is transferred into a fixed-bed tubular reactor. After the catalyst bed temperature reaches the reaction temperature, hexafluoropropylene dimer (organic material) and hydrogen are introduced. The flow rates of raw material hydrogen and hexafluoropropylene dimer are set according to the experimental conditions. After running for 8 hours, the product is washed with water and alkali and then analyzed by gas chromatography. The conversion rate of hexafluoropropylene dimer and the selectivity of the target product are calculated by the area normalization method. The catalyst lifetime is tested by extending the reaction time.

[0021] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention. The raw materials and reagents used in the following embodiments are all commercially available products.

[0022] Example 1: Preparation of 0.5Pd-2.0K-Cl / ferric fluoride-H2-200 catalyst Weigh 0.045 g of palladium chloride and 0.2 g of potassium chloride, dissolve them in 5 mL of aqueous solution, and add 5 g of nano-iron fluoride (the Fe / F molar ratio in the raw material for preparing nano-iron fluoride is 1 / 2) to the above impregnation solution. Impregnate in excess and let stand overnight. Dry in an oven at 120 ℃ for 12 h, calcine in a muffle furnace at 250 ℃ for 6 h, and then reduce by hydrogen at 200 ℃ for 6 h under a pure hydrogen atmosphere to obtain 0.5Pd-2.0K-Cl / iron fluoride-H2-200 catalyst.

[0023] Example 2: Preparation of 0.5Pd-2.0KN / ferric fluoride-H2-200 catalyst Weigh 0.066 g of palladium nitrate and 0.27 g of potassium nitrate, dissolve them in 5 mL of aqueous solution, and add 5 g of nano-iron fluoride (the Fe / F molar ratio in the raw material for preparing nano-iron fluoride is 1 / 2) to the above impregnation solution. Impregnate in excess and let stand overnight. Dry in an oven at 120 ℃ for 12 h, calcine in a muffle furnace at 200 ℃ for 6 h, and then reduce by hydrogen at 200 ℃ for 6 h under a pure hydrogen atmosphere to obtain 0.5Pd-2.0KN / iron fluoride-H2-200 catalyst.

[0024] Example 3: Preparation of 0.5Pd-OAC-2.0K-Cl / ferric fluoride-H2-200 catalyst Weigh 0.056 g of palladium acetate and 0.2 g of potassium chloride, dissolve them in 5 mL of aqueous solution, and add 5 g of nano-iron fluoride (the Fe / F molar ratio in the raw material for preparing nano-iron fluoride is 1 / 2) to the above impregnation solution. Impregnate in excess and let stand overnight. Dry in an oven at 120 ℃ for 12 h, calcine in a muffle furnace at 250 ℃ for 6 h, and then reduce by hydrogen at 250 ℃ for 6 h under a pure hydrogen atmosphere to obtain 0.5Pd-OAC-2.0K-Cl / iron fluoride-H2-200 catalyst.

[0025] Example 4: Preparation of 0.3Pd-Cl-1.0K-Cl / ferric fluoride-H2-200 catalyst Weigh 0.026 g of palladium chloride and 0.1 g of potassium chloride, dissolve them in 5 mL of aqueous solution, add 5 g of nano-iron fluoride (the Fe / F molar ratio in the raw material for preparing nano-iron fluoride is 1 / 2) to the above impregnation solution, impregnate with an equal volume and let stand overnight, dry in an oven at 120 °C for 12 h, calcine in a muffle furnace at 350 °C for 3 h, and then reduce by hydrogen at 300 °C for 6 h under a pure hydrogen atmosphere to obtain 0.3Pd-Cl-1.0K-Cl / iron fluoride-H2-200 catalyst.

[0026] Example 5: Preparation of 0.5Pd-2.0K-Cl / ferric fluoride-H2-150 catalyst Weigh 0.045 g of palladium chloride and 0.2 g of potassium chloride, dissolve them in 5 mL of aqueous solution, and add 5 g of nano-iron fluoride (the Fe / F molar ratio in the raw material for preparing nano-iron fluoride is 1 / 3) to the above impregnation solution. Impregnate in excess and let stand overnight. Dry in an oven at 120 ℃ for 12 h, calcine in a muffle furnace at 250 ℃ for 6 h, and then reduce by hydrogen at 150 ℃ for 8 h under a pure hydrogen atmosphere to obtain 0.5Pd-2.0K-Cl / iron fluoride-H2-150 catalyst.

[0027] Example 6: Preparation of 0.5Pd-2.0K-Cl / ferric fluoride-hydrazine hydrate catalyst Weigh 0.045 g of palladium chloride and 0.2 g of potassium chloride, dissolve them in 5 mL of aqueous solution, and add 5 g of nano-iron fluoride (the Fe / F molar ratio in the raw material for preparing nano-iron fluoride is 1 / 3) to the above impregnation solution. Impregnate in excess and let stand overnight. Dry in an oven at 120 ℃ for 12 h, calcine in a muffle furnace at 250 ℃ for 6 h, and then use a wet reduction method to add the above solid compound to 30 mL of 30% hydrazine hydrate solution and reduce at 50 ℃ for 3 h to obtain 0.5Pd-2.0K-Cl / iron fluoride-hydrazine hydrate catalyst.

[0028] Comparative Example 1: Preparation of 0.5Pd-2.0K-Cl / ferric fluoride-commercial-H2-200 catalyst Weigh 0.045 g of palladium chloride and 0.2 g of potassium chloride, dissolve them in 5 mL of aqueous solution, add 5 g of commercial ferric fluoride (purchased from Shaanxi Didu Pharmaceutical Chemical Co., Ltd.) to the above impregnation solution, impregnate in excess and let stand overnight, dry in an oven at 120 ℃ for 12 h, calcine in a muffle furnace at 250 ℃ for 6 h, and then reduce by hydrogen at 200 ℃ for 6 h under a pure hydrogen atmosphere to obtain 0.5Pd-Cl / ferric fluoride-commercial-H2-200 catalyst.

[0029] Performance testing: The catalysts prepared in the examples and comparative examples were used in the hydrogenation of hexafluoropropylene dimer to synthesize dodecafluorodihydrohexane. The final reaction mixture was tested, in which... Figure 1 The GC-MS spectrum of the hexafluoropropylene dimer used in the catalyst performance testing method prepared in Example 1 is shown below. The mass spectrometry results and their peak assignments are as follows: there is an ion peak at m / z = 69 for fragment -CF3 group, m / z = 93 for fragment -C=C-CF3, m / z = 131 for fragment -CF=CF-CF3, and m / z = 181 for fragment (CF3)2CF–C-, which confirms that the compound is the hexafluoropropylene dimer used in the reaction. Figure 2 This is the GC-MS spectrum of dodecafluorodihydrohexane, the product prepared by the catalyst performance testing method in Example 1. Figure 2 As can be seen, m / z = 69 is the ion peak of the fragment -CF3 group, m / z = 133 is the ion peak of the fragment -CHF-CHF-CF3, and m / z = 145 is the ion peak of the fragment -C-CHF-CHF-CF3, confirming that the compound is the reaction product dodecafluorodihydrohexane. The catalyst evaluation results are shown in Table 1. The results show that the comparative catalyst has a low conversion rate of the reactants and low selectivity for the target product, which is not conducive to further separation and purification.

[0030] Table 1

[0031] The stability of the catalysts in Example 1 and Comparative Example 1 was further tested at a reaction temperature of 100°C and a volume hourly space velocity of 20 h⁻¹. -1 The H2 / organic phase molar ratio was 3, and the results are shown in Table 2. The catalyst performance remained stable within the first 100 hours of reaction evaluation. The catalyst activity increased with reaction time, and both the feed conversion rate and the target product selectivity remained within a stable range. In contrast, the catalyst in Comparative Example 1 began to deactivate after 20 hours of reaction, and this deactivation continued unabated until the reaction reached 100 hours, at which point the catalyst activity dropped to approximately 12%, and the target product selectivity was approximately 54%.

[0032] Table 2

Claims

1. A palladium-potassium / nano-iron fluoride catalyst, characterized in that, The catalyst comprises a support and an active component, wherein the support is nano-iron fluoride and the active component is palladium and potassium.

2. The palladium-potassium / nano-iron fluoride catalyst according to claim 1, characterized in that, Based on the carrier mass, the mass percentage loading of the active component is 0.1% to 20%.

3. The palladium-potassium / nano-iron fluoride catalyst according to claim 1, characterized in that, The molar ratio of palladium to potassium is 1:(1~20).

4. The palladium-potassium / nano-iron fluoride catalyst according to claim 1, characterized in that, The catalyst preparation method includes: impregnating nano-iron fluoride in an aqueous solution containing palladium and potassium salts, then collecting the solid, and successively drying, calcining and reducing the solid to obtain a palladium-potassium / iron fluoride catalyst; The roasting temperature is 200–350°C; The reduction is performed using hydrogen reduction or wet reduction; the hydrogen reduction includes a reduction reaction at 150–300°C in the presence of hydrogen; the wet reduction includes a reduction reaction at 20–100°C in the presence of a reducing agent, wherein the reducing agent is selected from one or more combinations of sodium borohydride, hydrazine hydrate, hydrogen, and alcohols.

5. The palladium-potassium / nano-iron fluoride catalyst according to claim 4, characterized in that, The palladium salt is one or any combination of palladium chloride, palladium nitrate and palladium acetate, and the potassium salt is one or any combination of potassium chloride and potassium nitrate.

6. The palladium-potassium / nano-iron fluoride catalyst according to claim 4, characterized in that, The impregnation method adopts one or any combination of equal volume impregnation, excessive impregnation, and precipitation impregnation.

7. The application of the catalyst of claim 1 in the hydrogenation of hexafluoropropylene dimer to synthesize dodecafluorodihydrohexane.

8. The application according to claim 4, characterized in that, The molar ratio of raw material hydrogen to hexafluoropropylene dimer is (2-8):

1.

9. The application according to claim 4, characterized in that, The synthesis reaction temperature is 50–250℃, and the feed space velocity is 5–100 h⁻¹. -1 .

10. The application according to claim 4, characterized in that, The amount of catalyst used is 2-4g.

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