A method for efficiently preparing hexafluoro-2-butyne

Abstract

The present application relates to a kind of method for efficiently preparing hexafluoro-2-butynyl, first hexafluorobutadiene is vaporized, obtain hexafluorobutadiene gas, secondly supported catalyst is activated in nitrogen, then hexafluorobutadiene gas is carried out gas phase catalytic rearrangement using fixed bed reactor equipped with supported catalyst;Finally, the gas after rearrangement is removed by condenser Unreacted hexafluorobutadiene, obtain hexafluoro-2-butynyl.The present application reaction only needs one step, no by-product is generated, catalytic reaction yield is more than 80%, the conversion rate of whole process hexafluorobutadiene is >90%;After reaction, unreacted raw material can be directly reused, improve raw material utilization rate;The present application does not need to use solvent, also need not to carry out solvent and by-product separation and other operations, energy and material waste caused by separation process can be avoided.

Description

Technical Field

[0001] This invention relates to the field of chemical preparation technology, and specifically to a method for the efficient preparation of hexafluoro-2-butyne. Background Technology

[0002] Hexafluoro-2-butyne is an important fluorinated intermediate, serving as a raw material for the preparation of (Z)-hexafluoro-2-butene. It is also widely used in the synthesis of new materials such as trifluoromethyl bulk materials, yielding products with excellent properties, making it a promising fluorinated raw material. Hexafluoro-2-butyne is also an important fluorinated fine chemical raw material, used as a key intermediate in the synthesis of bis(trifluoromethyl) bulk materials, ODS substitutes, and as a monomer for fluorinated polymers, such as key intermediates in the synthesis of ortho-bis(trifluoromethyl)benzene rings or heterocycles. Furthermore, due to the unique structure of this fluorinated alkyne, hexafluoro-2-butyne possesses certain insulating properties, making it suitable as a fluorinated working fluid in the field of electrical insulation.

[0003] Currently, the preparation methods for hexafluoro-2-butyne involve complex reaction processes, often producing byproducts, resulting in low reaction yields, difficulties in product separation and purification, and resource waste. Patent CN 105348034A utilizes hexachlorobutadiene as a catalyst to synthesize hexafluoro-2-butyne through the action of cyclization, fluorination, and isomerization catalysts. However, this reaction route is lengthy and the product yield is low. Patent CN108530259A uses hexachlorobutadiene and a fluoride salt in an organic solvent to obtain the product. The gaseous reaction product is collected and then washed with water, alkali, and distilled to obtain hexafluoro-2-butyne. This demonstrates the complexity of subsequent product purification processes. Furthermore, the presence of organic solvents in this reaction complicates the chemical reaction and generates byproducts. Summary of the Invention

[0004] To address the problems of complex reaction processes, difficult product separation and purification, and low product conversion rates in existing technologies, this invention provides a technical solution for preparing hexafluoro-2-butyne with fewer reaction steps and higher conversion rates.

[0005] The technical solution adopted in this invention is: a method for efficiently preparing hexafluoro-2-butyne, comprising the following steps: raw material vaporization-catalyst activation-catalytic rearrangement-condensation separation to obtain the target product hexafluoro-2-butyne.

[0006] Step 1: Gasification of raw materials. Hexafluorobutadiene is vaporized to obtain hexafluorobutadiene gas;

[0007] Step 2: Catalyst activation, the supported catalyst is activated in nitrogen;

[0008] Step 3: Catalytic rearrangement. The hexafluorobutadiene gas obtained in Step 1 is subjected to gas-phase catalytic rearrangement under the action of a supported catalyst.

[0009] Step 4: Condensation and separation. The gas after the gas-phase catalytic rearrangement reaction in Step 3 is passed through a condenser to remove unreacted hexafluorobutadiene, yielding hexafluoro-2-butyne.

[0010] Preferably, the vaporization temperature in step 1 is 30℃~60℃, and the water content of the vaporized hexafluorobutadiene is <10pm; preferably, the loading process of the supported catalyst in step 2 is as follows:

[0011] a) Prepare a catalyst solution with a mass fraction of 60%–80%, wherein the catalyst is one or more of sodium fluoride, potassium fluoride, and cesium fluoride.

[0012] b) Immerse the molecular sieve in the catalyst solution and stir for 6 hours. The mass ratio of catalyst solution to molecular sieve is 1:0.1-0.3.

[0013] c) The impregnated molecular sieve loaded with catalyst is dried at 200°C for 8 hours, and then calcined at 500°C to 600°C for 12 hours under a nitrogen atmosphere; preferably, the catalyst support is a 3A, 4A, 5A, 13X, Y-type molecular sieve or alumina.

[0014] Preferably, in step 2, the loading of the supported catalyst is 1% to 30%, and the catalyst space velocity is 60 to 200 h⁻¹; preferably, in step 3, the reaction pressure of the fixed-bed reactor is 0 to 0.5 MPa, and the reaction temperature is 100 to 200 °C; preferably, in step 3, the condensation temperature of the condenser is -5 to 0 °C. Within this temperature range, the product can be effectively separated to obtain a high-purity product, hexafluoro-2-butyne, and the unreacted liquid hexafluorobutadiene can be returned to the system to participate in the reaction.

[0015] The beneficial effects of this invention are as follows:

[0016] (1) The reaction steps of this invention are simple, requiring only one catalytic rearrangement step to obtain the target product hexafluoro-2-butyne.

[0017] (2) The catalytic reaction yield of the present invention is above 80%, and the conversion rate of hexafluorobutadiene in the whole process is >90%;

[0018] (3) After the reaction is completed, the unreacted raw materials can be directly reused, thereby improving the utilization rate of raw materials;

[0019] (4) This invention does not require the use of solvents, the reaction is simple, no by-products are generated, and there is no need to perform operations such as solvent and by-product separation, which can avoid the waste of energy and materials caused by the separation process. Attached Figure Description

[0020] Figure 1 This is a process flow diagram of the catalytic reaction.

[0021] Figure 2 The mass spectrum of the product is hexafluoro-2-butyne. Detailed Implementation

[0022] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0023] like Figure 1 As shown, the present invention provides a method for the efficient preparation of hexafluoro-2-butyne, which mainly involves the vaporization of raw materials, activation of catalyst, catalytic rearrangement, and condensation separation to obtain the target product hexafluoro-2-butyne. Unreacted hexafluorobutadiene is vaporized and reused.

[0024] Specifically, the following steps are included:

[0025] Step 1: Gasification of raw materials. Hexafluorobutadiene is vaporized to obtain hexafluorobutadiene gas;

[0026] Step 2: Catalyst activation, the supported catalyst is activated in nitrogen;

[0027] Step 3: Catalytic rearrangement. The hexafluorobutadiene gas obtained in Step 1 is subjected to gas-phase catalytic rearrangement under the action of a supported catalyst.

[0028] Step 4: Condensation and separation. The gas after the catalytic rearrangement reaction in Step 3 is passed through a condenser to remove unreacted hexafluorobutadiene, yielding hexafluoro-2-butyne.

[0029] The reaction equation is: CF2=CFCF=CF2→CF3C≡CCF3.

[0030] Example 1

[0031] Step 1: Vaporize hexafluorobutadiene at a temperature of 45°C. The water content of the vaporized hexafluorobutadiene should be less than 10 μm.

[0032] Step 2: The catalyst is supported on 5A molecular sieve with 10% cesium fluoride and activated at 500℃ for 12h;

[0033] Step 3: The vaporized hexafluorobutadiene is subjected to gas-phase catalytic rearrangement in a fixed-bed reactor equipped with a supported catalyst. The catalyst space velocity is 150 h⁻¹, the reaction pressure of the fixed-bed reactor is 0.1 MPa, and the reaction temperature is 150 °C.

[0034] Step 4: The gas obtained from the catalytic reaction in Step 3 is passed into a condenser to remove unreacted hexafluorobutadiene. The temperature of the condenser is -5 to 0°C, yielding hexafluoro-2-butyne gas. Based on the above steps, the catalytic reaction yield is 90%, and the hexafluorobutadiene conversion rate is 99%.

[0035] Comparative Example 1

[0036] Based on Example 1, the main technical difference between Comparative Example 1 and Example 1 is that the supported catalyst was used directly without activation, resulting in a catalytic reaction yield of 50% and a hexafluorobutadiene conversion rate of 60%. It can be seen that the activated supported catalyst can improve the catalytic reaction yield and hexafluorobutadiene conversion rate.

[0037] Comparative Example 2

[0038] Based on Example 1, the main technical difference between Comparative Example 1 and Example 1 is that the catalytic time of the supported catalyst is set in multiple ways, and the catalytic reaction yield and hexafluorobutadiene conversion rate are tested, as shown in Table 1.

[0039] Table 1 Activation time of supported catalysts

[0040] Nitrogen atmosphere activation time (h) 0 4 8 12 16 20 24 Reaction yield (%) 50 75 85 92 90 90 90 Conversion rate (%) 60 93 99 99 99 99 99

[0041] Based on the table above, we can conclude that as the activation time of the supported catalyst is extended, the catalytic reaction yield increases in the range of 4 to 12 hours, but after 12 hours, the catalytic reaction yield no longer increases; the conversion rate of hexafluorobutadiene remains above 90%, but as the activation time of the supported catalyst is extended, the conversion rate does not increase significantly.

[0042] Example 2

[0043] Step 1: Vaporize hexafluorobutadiene at a temperature of 45°C. The water content of the vaporized hexafluorobutadiene should be less than 10 μm.

[0044] Step 2: The catalyst is made of alumina supported with 5% potassium fluoride and activated at 550℃ for 12h;

[0045] Step 3: The vaporized hexafluorobutadiene is subjected to gas-phase catalytic rearrangement in a fixed-bed reactor equipped with a supported catalyst. The catalyst space velocity is 80 h⁻¹, the reaction pressure of the fixed-bed reactor is 0.1 MPa, and the reaction temperature is 180 °C.

[0046] Step 4: The gas obtained from the catalytic reaction in Step 3 is passed into a condenser to remove unreacted hexafluorobutadiene. The temperature of the condenser is -5 to 0°C, yielding hexafluoro-2-butyne gas. Based on the above steps, the catalytic reaction yield is 92%, and the hexafluorobutadiene conversion rate is 99%.

[0047] Example 3

[0048] Step 1: Vaporize hexafluorobutadiene at a temperature of 45°C. The water content of the vaporized hexafluorobutadiene should be less than 10 μm.

[0049] Step 2: The catalyst is 5A supported with 5% potassium fluoride and activated at 600℃ for 8 hours;

[0050] Step 3: The vaporized hexafluorobutadiene was subjected to gas-phase catalytic rearrangement in a fixed-bed reactor equipped with a supported catalyst. The catalyst space velocity was 60 h⁻¹, the reaction pressure of the fixed-bed reactor was 0.1 MPa, and the reaction temperature was 100 °C.

[0051] Step 4: The gas obtained from the catalytic reaction in Step 3 is passed into a condenser to remove unreacted hexafluorobutadiene. The temperature of the condenser is -5 to 0°C, yielding hexafluoro-2-butyne gas. Based on the above steps, the catalytic reaction yield is 85%, and the hexafluorobutadiene conversion rate is 99%.

[0052] Example 4

[0053] Step 1: Vaporize hexafluorobutadiene at a temperature of 45°C. The water content of the vaporized hexafluorobutadiene should be less than 10 μm.

[0054] Step 2: The catalyst is 4A supported with 5% potassium fluoride and 10% cesium fluoride, and activated at 550℃ for 8 hours;

[0055] Step 3: The vaporized hexafluorobutadiene was subjected to gas-phase catalytic rearrangement in a fixed-bed reactor equipped with a supported catalyst. The catalyst space velocity was 60 h⁻¹, the reaction pressure of the fixed-bed reactor was 0.1 MPa, and the reaction temperature was 100 °C.

[0056] Step 4: The gas obtained from the catalytic reaction in Step 3 is passed into a condenser to remove unreacted hexafluorobutadiene. The temperature of the condenser is -5 to 0°C, yielding hexafluoro-2-butyne gas. Based on the above steps, the catalytic reaction yield is 90%, and the hexafluorobutadiene conversion rate is 99%.

[0057] Mass spectra of hexafluoro-2-butyne products from Examples 1-4 and accompanying diagrams Figure 1 Therefore, only the mass spectrometry chromatogram of the product hexafluoro-2-butyne from Example 1 is shown in the accompanying drawings.

[0058] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing hexafluoro-2-butyne, characterized in that: Includes the following steps, Step 1: Gasification of raw materials. Hexafluorobutadiene is vaporized to obtain hexafluorobutadiene gas; Step 2: Catalyst activation, the supported catalyst is activated in nitrogen; Step 3: Catalytic rearrangement. The hexafluorobutadiene gas obtained in Step 1 undergoes gas-phase catalytic rearrangement under the action of a supported catalyst. Step 4: Condensation and separation. The gas after the gas-phase catalytic rearrangement reaction in Step 3 is passed through a condenser to remove unreacted hexafluorobutadiene, yielding hexafluoro-2-butyne. The loading process of the supported catalyst in step 2 is as follows: a) Prepare a catalyst solution with a mass fraction of 60%–80%, wherein the catalyst is one or more of sodium fluoride, potassium fluoride, and cesium fluoride. b) Immerse the catalyst support in the catalyst solution and stir for 6 hours. The mass ratio of catalyst solution to catalyst support is 1:0.1~0.

3. c) The molecular sieve with impregnated catalyst is dried at 200℃ for 8h, and then calcined at 500℃~600℃ for 12h under nitrogen atmosphere; The catalyst support is a 3A, 4A, 5A, 13X, Y-type molecular sieve or alumina; The supported catalyst has a loading of 1% to 30% and a space velocity of 60 h⁻¹ to 200 h⁻¹.

2. The method for preparing hexafluoro-2-butyne according to claim 1, characterized in that: The vaporization temperature in step 1 is 30℃~60℃, and the water content of the vaporized hexafluorobutadiene is <10pm.

3. The method for preparing hexafluoro-2-butyne according to claim 1, characterized in that: In step 3, the reaction pressure of the gas-phase catalytic rearrangement is 0 MPa to 0.5 MPa, and the reaction temperature is 100℃ to 200℃.

4. The method for preparing hexafluoro-2-butyne according to claim 1, characterized in that: In step 3, the condensation temperature of the condenser is -5℃ to 0℃.

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