A method for preparing trans-1,1,1,4,4,4-hexafluoro-2-butene

Abstract

The present invention belongs to the field of fluorine chemical technology, and specifically relates to a method for preparing trans-1,1,1,4,4,4-hexafluoro-2-butene. The method for preparing trans-1,1,1,4,4,4-hexafluoro-2-butene comprises the following steps: reacting HF with a compound CF3CHClCH2CF x Cl 3‑x Under the action of a fluorination catalyst, a gas phase fluorination reaction occurs to prepare trans-1,1,1,4,4,4-hexafluoro-2-butene, wherein the compound CF3CHClCH2CF x Cl 3‑x wherein x=1, 2 or 3. The method for preparing trans-1,1,1,4,4,4-hexafluoro-2-butene of the present invention produces less three wastes, has high reaction selectivity, and has a long catalyst life, can effectively reduce production costs, and is conducive to large-scale industrial production.

Description

Technical Field

[0001] The invention belongs to the technical field of fluorine chemical industry, and particularly relates to a method for preparing trans-1,1,1,4,4,4-hexafluoro-2-butene. Background Art

[0002] 1,1,1,4,4,4-Hexafluoro-2-butene (HFO-1336mzz) exists in both cis and trans configurations. The trans form (E-HFO-1336mzz) has a boiling point of 7.5°C and is a colorless, odorless, non-flammable gas at room temperature and pressure. It exhibits favorable environmental properties (ODP = 0, GWP = 18, and an atmospheric lifetime of only 22 days), is highly safe, non-toxic, flame-retardant, oil-soluble, and has good material compatibility. As a newly developed gas, E-HFO-1336mzz exhibits similar excellent properties as an electrical insulator and arc-extinguishing medium, while also possessing a low GWP, meeting environmental requirements and promising applications in electrical insulation. E-HFO-1336mzz has a higher relative dielectric strength than SF6 and can be used as an insulating gas / arc-extinguishing medium in electrical equipment exceeding 1 kV. The HFO-1336mzz molecule carries six fluorine atoms on its two terminal methyl groups, which can be dissociated (e.g., forming negatively charged fluoride ions) to generate gas discharge and form precursor dielectric breakdown. Furthermore, compared to other new insulating gases (primarily fluorinated ketones and fluorinated nitriles), E-HFO-1336mzz has a short atmospheric lifetime and low toxicity.

[0003] DuPont CN102015592B reported the preparation of trans-1,1,1,4,4,4-hexafluoro-2-butene by reacting 1,1-dichloro-2,2,2-trifluoroethane with copper as raw materials. This route requires the use of chemical amounts of elemental copper, produces a lot of waste, and has low prospects for industrialization.

[0004] Chinese patent CN109553506B reports that under the action of Nx / MgF2 fluorination catalyst, N is the active component selected from one of Al, Cu, Zn or Co, 1,1,1,3-tetrachloro-4,4,4-trifluorobutane and HF are subjected to gas-phase fluorination reaction to synthesize trans-1,1,1,4,4,4-hexafluoro-2-butene. The reaction temperature is 200-300°C, the molar ratio of HF to 1,1,1,3-tetrachloro-4,4,4-trifluorobutane is 5-50:1, and the selectivity of trans-1,1,1,4,4,4-hexafluoro-2-butene is about 97.0%. Summary of the Invention

[0005] In response to the shortcomings and deficiencies of the prior art, the present invention provides a method for preparing trans-1,1,1,4,4,4-hexafluoro-2-butene. This method produces minimal waste, exhibits high reaction selectivity, and offers a long catalyst life, effectively reducing production costs and facilitating large-scale industrial production.

[0006] In order to achieve the above object, the present invention adopts the following technical scheme: a method for preparing trans-1,1,1,4,4,4-hexafluoro-2-butene, comprising the following steps:

[0007] HF and compound CF3CHClCH2CF x Cl 3-x Under the action of fluorination catalyst, gas phase fluorination reaction occurs to prepare trans-1,1,1,4,4,4-hexafluoro-2-butene, wherein the compound CF3CHClCH2CF x Cl 3-x where x=1, 2 or 3.

[0008] In the present invention, the operating pressure of the reaction is primarily controlled by the saturated vapor pressure of the reactants at the reaction temperature and is generally not strictly controlled. The reaction can be carried out at a pressure below, equal to, or above atmospheric pressure, preferably above atmospheric pressure. Furthermore, the reaction of the present invention can be operated batchwise or continuously, and the reaction itself has no significant requirements for the reaction mode.

[0009] Preferably, the HF and the compound CF3CHClCH2CF x Cl 3-x The molar ratio is (2-50):1, the reaction temperature is 240-320°C, and the residence time is 2s-20s.

[0010] Preferably, the compound CF3CHClCH2CF x Cl 3-x It is CF3CHClCH2CF2Cl.

[0011] More preferably, the HF and the compound CF3CHClCH2CF x Cl 3-x The molar ratio is (10-20):1, the reaction temperature is 280-300°C, and the residence time is 6s-10s.

[0012] Preferably, the fluorination catalyst is a supported catalyst having a composition of AB / MgF2, wherein A is an active component selected from one of Fe, Mn or Y; B is an active auxiliary selected from one of Sc, Gd or Ba; and MgF2 is active magnesium fluoride.

[0013] Preferably, the molar ratio of A, B and Mg in the fluorination catalyst is (0.5-1.5):(0.1-0.5):(8.0-9.4).

[0014] More preferably, the molar ratio of A, B and Mg in the fluorination catalyst is (1.0-1.2):(0.2-0.3):(8.5-8.8).

[0015] Preferably, the surface area of ​​MgF2 in the fluorination catalyst is 100 to 140 m 2 / g.

[0016] The present invention uses a composite supported catalyst, and an overall synergistic effect is formed between the active component, the active auxiliary agent, and the carrier. The active components Fe, Mn, or Y selected in the present invention provide active sites with moderate activity for the fluorination reaction, and can obtain excellent stability under the cooperation of the active auxiliary agent; the active auxiliary agent Sc, Gd, or Ba can not only disperse the active component, but also enhance the overall water resistance and sintering resistance of the catalyst; the carrier with a large specific surface area is conducive to the dispersion of the active component and the active auxiliary agent, maximizing the effect of the active component, and the active magnesium fluoride itself plays a regulating and supporting role on the catalyst. The synergistic effect of the active component, the active auxiliary agent, and the carrier can not only improve the selectivity of the reaction, but also further enhance the stability of the catalyst and extend its service life.

[0017] Preferably, the preparation method of the fluorination catalyst comprises the following steps:

[0018] S1. Preparation of active magnesium fluoride carrier MgF2: hydrofluoric acid is added dropwise to a 1,2-propylene glycol solution of Mg(NO3)2 under stirring for fluorination treatment, wherein the molar ratio of hydrofluoric acid to Mg(NO3)2 is 3-5:1. After the addition is completed, stirring is continued for 1-10 hours to obtain a liquid sol; the liquid sol is allowed to stand and age at 50-80°C for 12-48 hours to obtain a solid gel; the solid gel is dried at 120-140°C for 30 hours to obtain an active magnesium fluoride carrier MgF2;

[0019] S2. Preparation of supported catalyst AB / MgF2: The soluble salts of the active agent B and the active component A are respectively impregnated on the active magnesium fluoride support MgF2 by the impregnation method. Finally, the supported catalyst AB / MgF2 is obtained by drying at a temperature of 100°C to 150°C and calcining at a temperature of 250°C to 350°C.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The method for preparing trans-1,1,1,4,4,4-hexafluoro-2-butene of the present invention has the advantages of high catalytic activity and high product selectivity. At the same time, the catalyst has a long service life. After the reaction is continuously operated for 500 hours, the conversion rate of CF3CHClCH2CF2Cl can reach 100%, and the selectivity of E-HFO-1336mzz can be maintained at above 99.0%. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the hydrogen spectrum of trans-1,1,1,4,4,4-hexafluoro-2-butene prepared in Example 1 of the present invention.

[0023] Figure 2 This is the carbon spectrum of trans-1,1,1,4,4,4-hexafluoro-2-butene prepared in Example 1 of the present invention.

[0024] Figure 3 This is the fluorine spectrum of trans-1,1,1,4,4,4-hexafluoro-2-butene prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] In the Examples and Comparative Examples, the experimental methods used are conventional methods unless otherwise specified, and the materials and reagents used are commercially available unless otherwise specified.

[0027] Example 1

[0028] Add 0.85 mol of MgF2 active carrier into a beaker, and use the impregnation method to impregnate FeCl3·6H2O and Sc2(SO3)2·5H2O, the molar ratio of FeCl3·6H2O, Sc2(SO3)2·5H2O and MgF2 is 1.2:0.15:8.5, dry in an oven at 100°C for 20 hours, and calcine in a muffle furnace at 350°C-400°C-450°C in stages, maintaining each temperature section for 5 hours to prepare a supported catalyst 12Fe-3Sc / MgF2.

[0029] 5 mL of the catalyst prepared in the above steps was measured and loaded into the reaction tube. After the reaction temperature stabilized at 280°C, HF and CF3CHClCH2CF2Cl were introduced respectively. The contact time was 6 s and the molar ratio of HF to CF3CHClCH2CF2Cl was 20:1. The reaction was run for 24 h. The reaction product was washed with HF, collected at -10°C and dried, and then analyzed by gas chromatography.

[0030] The conversion rate of CF3CHClCH2CF2Cl is 100%, and the selectivity of E-HFO-1336mzz is 99.7% (100% means almost equivalent to 100%).

[0031] The NMR data of the trans-1,1,1,4,4,4-hexafluoro-2-butene (99.0%) sample obtained by distillation are as follows:

[0032] 1H NMR (500MHz,CDCl3)δ6.41(m,2H), see attached Figure 1 ;

[0033] 13C NMR 126.7 (qq, J = 36.8, 6 Hz), 121.3 (q, J = 268.5 Hz), see Appendix Figure 2 ;

[0034] 19F NMR (470.0MHz,CDCl3)δ-66.9(s,CF3), see attached Figure 3 .

[0035] Example 2

[0036] Add 0.88 mol of MgF2 active carrier into a beaker, and use the impregnation method to impregnate MnPO4·H2O and Gd(NO3)3·6H2O. The molar ratio of MnPO4·H2O, Gd(NO3)3·6H2O and MgF2 is 1.0:0.2:8.8. Dry in an oven at 100°C for 20 hours, and calcine in a muffle furnace at 350°C-400°C-450°C in stages, maintaining each temperature section for 5 hours to prepare the catalyst 10Mn-2Gd / MgF2.

[0037] 5 mL of the catalyst prepared in the above steps was measured and loaded into the reaction tube. After the reaction temperature stabilized at 300°C, HF and CF3CHClCH2CF2Cl were introduced respectively. The contact time was 10 s, and the molar ratio of HF to CF3CHClCH2CF2Cl was 20:1. The reaction was run for 24 h. The reaction product was washed with HF, collected at -10°C and dried, and then analyzed by gas chromatography.

[0038] Example 3

[0039] Add 0.08 mol of MgF2 active carrier into a beaker, and use the impregnation method to impregnate Y(NO3)3·6H2O and BaCl2·2H2O, the molar ratio of Y(NO3)3·6H2O, BaCl2·2H2O and MgF2 is 1.5:0.1:8.0, dry in an oven at 100°C for 20 hours, and calcine in a muffle furnace at 350°C-400°C-450°C in stages, maintaining each temperature section for 5 hours to prepare a supported catalyst 15Y-Ba / MgF2.

[0040] 5 mL of the catalyst prepared in the above steps was measured and loaded into the reaction tube. After the reaction temperature stabilized at 320°C, HF and CF3CHClCH2CF2Cl were introduced respectively. The contact time was 20 s, and the molar ratio of HF to CF3CHClCH2CF2Cl was 20:1. The reaction was run for 24 h. The reaction product was washed with HF, collected at -10°C and dried, and then analyzed by gas chromatography.

[0041] Examples 4-5

[0042] Compared with Example 1, the difference between Examples 4 and 5 is that the compound CF3CHClCH2CF x Cl 3-x Here x is 1 or 3.

[0043] For other raw materials and preparation methods, refer to Example 1.

[0044] Examples 6 to 9

[0045] Compared with Example 1, Examples 6 to 9 differ in that different catalyst compositions are used. The specific parameters are shown in Table 1 below.

[0046] For other raw materials and preparation methods, refer to Example 1.

[0047] Table 1

[0048] Group AB / Mg Example 6 Fe-Gd / Mg Example 7 Mn-Ba / Mg Example 8 Y-Sc / Mg Example 9 Fe-Ba / Mg

[0049] Examples 10 to 15

[0050] The difference between Examples 10 to 15 and Example 1 is that different reaction conditions are selected. The specific parameters are shown in Table 2 below.

[0051] For other raw materials and preparation methods, refer to Example 1.

[0052] Table 2

[0053]

[0054] Comparative Examples 1 to 3

[0055] The difference between Comparative Examples 1 to 3 and Example 1 is that different catalyst components are selected. The specific parameters are shown in Table 3.

[0056] For other raw materials and preparation methods, refer to Example 1.

[0057] Table 3

[0058]

[0059]

[0060] Comparative Examples 4 to 7

[0061] Comparative Examples 4 to 7 are different from Example 1 in that the molar ratios of A, B, and Mg in the selected catalysts are different. The specific parameters are shown in Table 4.

[0062] For other raw materials and preparation methods, refer to Example 1.

[0063] Table 4

[0064] Group AB / Mg AB / Mg molar ratio Comparative Example 4 <![CDATA[Fe-Sc / MgF2]]> 0：0.3：9.7 Comparative Example 5 <![CDATA[Fe-Sc / MgF2]]> 0.2：0.5：9.3 Comparative Example 6 <![CDATA[Fe-Sc / MgF2]]> 1.5：0：8.5 Comparative Example 7 <![CDATA[Fe-Sc / MgF2]]> 2.0：1.5：6.5

[0065] Comparative Examples 8 to 11

[0066] Comparative Examples 8 to 9 are different from Example 1 in that the residence times of HF and 2,4-dichloro-1,1,1,4,4-pentafluorobutane are different;

[0067] Comparative Examples 10 to 11 differ from Example 1 in that different molar ratios of HF and 2,4-dichloro-1,1,1,4,4-pentafluorobutane are used. The specific parameters are shown in Table 5.

[0068] For other raw materials and preparation methods, refer to Example 1.

[0069] Table 5

[0070]

[0071] Test Example 1: Conversion rate and selectivity determination

[0072] The selectivity and raw material conversion data of E-HFO-1336mzz prepared by the preparation methods of Examples 1 to 15 and Comparative Examples 1 to 11 are shown in Table 6.

[0073] Table 6 Conversion rate and selectivity data results of each sample

[0074]

[0075]

[0076] Test Example 2: Catalyst Service Life Test

[0077] A certain amount of the catalyst prepared in Example 1 was measured and loaded into the reaction tube. After the reaction temperature was stabilized at 280° C., CF3CHClCH2CF2Cl and HF were continuously pumped into the reactor by metering pumps. The feed rate of CF3CHClCH2CF2Cl was 15.3 g / h, the feed rate of HF was 20 g / h, and the contact time was 10 s. The reaction product was washed with water to remove acid and dried, and then analyzed by gas chromatography. The reaction results are shown in Table 7.

[0078] As shown in Table 7, after 500 h of continuous operation, the conversion rate of CF3CHClCH2CF2Cl is 100%, and the selectivity of E-HFO-1336mzz can be maintained above 99%. This proves that the fluorination catalyst prepared by the present invention has a long service life and is suitable for long-term use.

[0079] Table 7

[0080]

[0081]

[0082] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A method for preparing trans-1,1,1,4,4,4-hexafluoro-2-butene, characterized in that: The following steps are involved: HF and compound CF3CHClCH2CF x Cl 3-x Under the action of fluorination catalyst, gas phase fluorination reaction occurs to prepare trans-1,1,1,4,4,4-hexafluoro-2-butene, wherein the compound CF3CHClCH2CF x Cl 3-x where x = 1, 2, or 3; The HF and compound CF3CHClCH2CF x Cl 3-x The molar ratio is (10-20):1, and the residence time is 6s-10s; The fluorination catalyst is a supported catalyst having a composition of AB / MgF2, wherein A is an active component selected from one of Fe, Mn or Y; B is an active auxiliary selected from one of Sc, Gd or Ba; MgF2 is active magnesium fluoride; and the molar ratio of A, B and Mg in the fluorination catalyst is (0.5-1.5):(0.1-0.5):(8.0-9.4).

2. The method for preparing trans-1,1,1,4,4,4-hexafluoro-2-butene according to claim 1, wherein: The reaction temperature is 240°C to 320°C.

3. The method for preparing trans-1,1,1,4,4,4-hexafluoro-2-butene according to claim 1, wherein: The compound CF3CHClCH2CF x Cl 3-x It is CF3CHClCH2CF2Cl.

4. The method for preparing trans-1,1,1,4,4,4-hexafluoro-2-butene according to claim 2, wherein: The reaction temperature is 280-300°C.

5. The method for preparing trans-1,1,1,4,4,4-hexafluoro-2-butene according to claim 1, wherein: The molar ratio of A, B and Mg in the fluorination catalyst is (1.0-1.2): (0.2-0.3): (8.5-8.8).

6. The method for preparing trans-1,1,1,4,4,4-hexafluoro-2-butene according to claim 1, wherein: The surface area of ​​MgF2 in the fluorination catalyst is 100 to 140 m 2 / g.

7. The method for preparing trans-1,1,1,4,4,4-hexafluoro-2-butene according to claim 5, wherein: The preparation method of the fluorination catalyst comprises the following steps: first preparing an active magnesium fluoride carrier MgF2, then using an impregnation method to impregnate the soluble salts of an active auxiliary agent B and an active component A on the active magnesium fluoride carrier, respectively, and finally drying at a temperature of 100°C to 150°C and calcining at a temperature of 250°C to 350°C to prepare a supported catalyst AB / MgF2.

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