Confined-range alloy catalyst for synthesizing hexafluoro-1, 3-butadiene as well as preparation method and application of limited-range alloy catalyst

Abstract

The invention relates to a preparation method of a catalyst for synthesizing hexafluoro-1, 3-butadiene, in particular to a confinement alloy catalyst for synthesizing hexafluoro-1, 3-butadiene as well as a preparation method and application of the confinement alloy catalyst. The preparation method comprises the following steps: adding a silicon-based template, a solvent and a metal salt precursor into a hydrothermal kettle, carrying out hydrothermal treatment for a period of time, then carrying out centrifugal separation and drying on the obtained product, and finally putting the product into a muffle furnace for roasting to obtain the confinement alloy catalyst. The preparation method is simple in process and easy to repeat; the prepared confinement alloy catalyst is relatively long in service life, and has relatively high conversion rate and selectivity when being used for a reaction for preparing hexafluoro-1, 3-butadiene through continuous hydrogenation coupling of 1, 1, 2-trifluoro-1, 2, 2-trichloroethane.

Description

Technical Field

[0001] The invention relates to a method for preparing a catalyst for synthesizing hexafluoro-1,3-butadiene, in particular to a confined alloy catalyst for synthesizing hexafluoro-1,3-butadiene and a preparation method and application thereof. Background Art

[0002] Hexafluorobutadiene, also known as perfluorobutadiene, abbreviated as HFBD, has a molecular formula of C4F6. Hexafluorobutadiene is an important monomer of synthetic resins and fluorine-containing substances. It can also be used as an etching gas in the semiconductor industry, with the advantages of good selectivity and high precision. In addition, compared with traditional perfluoroalkane (PFCs) etching gases, hexafluorobutadiene can be used in high aspect ratio processes, and the pollution to the atmosphere and the environment is relatively small. With the rapid development of the semiconductor industry and the increasingly high environmental requirements in today's world, it has become a general trend to replace the widely used PFCs with relatively environmentally friendly materials. Generally speaking, electronic gases have high requirements for purity, and their impurity content is generally at the 10-6 level or even the 10-9 level.

[0003] The critical temperature of hexafluorobutadiene is 136.75°C, which is greater than 65°C. It is a low-pressure liquefied gas that is insoluble in water and has a wide combustion limit in air, making it prone to explosion. Hexafluorobutadiene contains two carbon-carbon double bonds and is prone to addition and polymerization reactions. Therefore, it can be used as a monomer for the preparation of perfluoropolymers in industry. In addition, hexafluorobutadiene can also react violently with oxidants, alkali metals, and strong alkali solutions.

[0004] Zhang Zhiyong et al. [Organofluorine Industry, 2016(4): 8-10.] Using 3,4-dichloro-hexafluoro-1-butene as an intermediate for dechlorination reaction, 3,4-dichloro-hexafluoro-1-butene was slowly added into the reactor in the presence of zinc powder, and the reaction temperature was controlled at 38-45 °C. The following reaction occurred to generate hexafluorobutadiene:

[0005] The method uses ethanol as solvent and excessive zinc powder, the selectivity of the reaction is greater than 96%, and the product yield is 94%. A Chinese invention with publication number CN106336342A provides a method for synthesizing hexafluorobutadiene using iodine and chlorine as raw materials. Iodine and chlorine are reacted at a reaction temperature of 55 to 70 °C to obtain iodine monochloride; in a metal complex ion solvent, chlorotrifluoroethylene and iodine monochloride are reacted at 20 to 60 °C and 0.1 to 1 MPa for 5 to 10 h to obtain 1,2-dichloro-2-iodo-1,1,2-trifluoroethane, which is purified by extraction and distillation; the purified 1,2-dichloro-2-iodo-1,1,2-trifluoroethane is reacted in a metal complex ion solvent with zinc as a catalyst at 10 to 40 °C for 7 to 20 h to obtain tetrachlorohexafluorobutane, and then tetrachlorohexafluorobutane and zinc are reacted at a molar ratio of 1:2.1 to 2.5 to obtain hexafluorobutadiene. The invention selects appropriate process conditions, and the yield and selectivity of hexafluorobutadiene can reach 95% and 99% respectively.

[0006] In summary, at present, the current research is mainly focused on the synthesis of tetrahalogen hexafluorobutane intermediates. The raw materials required for the synthesis of tetrahalogen hexafluorobutane intermediates are low in price and have a high yield, but the preparation process is long. The intermediate will produce a large amount of zinc halide during the dehalogenation reaction, and the waste treatment process is also relatively complicated. Therefore, improving the reaction process, discovering a new reaction, and finding a faster synthesis method will be a focus of future research on hexafluorobutadiene. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene with a simple process and a preparation method and application thereof.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing a confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene, comprising the following steps: adding a silicon-based template, a solvent and a metal salt precursor to a hydrothermal kettle, hydrothermally treating for a period of time, then centrifuging and drying the obtained product, and finally placing it in a muffle furnace for calcination to obtain a confined alloy catalyst.

[0009] Another technical solution adopted by the present invention is: a confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene, which is prepared by using the above-mentioned preparation method of the confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene.

[0010] Another technical solution adopted by the present invention is: the application of the above-mentioned confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene in the reaction of continuous hydrogenation coupling of 1,1,2-trifluoro-1,2,2-trichloroethane (CF2ClCFCl2, CFC-113) to prepare hexafluoro-1,3-butadiene.

[0011] The beneficial effects of the present invention are as follows: the present invention provides a method for preparing a confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene for the continuous hydrogenation coupling of 1,1,2-trifluoro-1,2,2-trichloroethane, and the preparation method has a simple process and is easy to repeat; the prepared confined alloy catalyst has a long service life and has a high conversion rate and selectivity when used for the continuous hydrogenation coupling reaction of 1,1,2-trifluoro-1,2,2-trichloroethane to prepare hexafluoro-1,3-butadiene. DETAILED DESCRIPTION

[0012] In order to explain the technical content, achieved objectives and effects of the present invention in detail, the following is an explanation in conjunction with the implementation modes.

[0013] A method for preparing a confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene comprises the following steps: adding a silicon-based template, a solvent and a metal salt precursor into a hydrothermal kettle, performing hydrothermal treatment for a period of time, then centrifugally separating and drying the obtained product, and finally placing the product into a muffle furnace for calcination to obtain the confined alloy catalyst.

[0014] From the above description, it can be seen that the beneficial effects of the present invention are: the preparation method of the present invention is simple in process, easy to repeat, and suitable for large-scale preparation; the prepared confined alloy catalyst has excellent catalytic performance, is easy to regenerate, can be reused, has high economic benefits, and has excellent industrial application prospects.

[0015] Furthermore, the silicon-based template is any one of nano-SiO2, ZSM-5 molecular sieve, silicalite-1 molecular sieve and SBA-15 molecular sieve.

[0016] Preferably, the silicon-based template is SBA-15 molecular sieve or silicalite-1 molecular sieve.

[0017] Furthermore, the solvent is an alcohol / water mixed solvent, and the volume ratio of alcohol to water in the solvent is 10:1~1:1.

[0018] Preferably, the volume ratio of alcohol to water in the solvent is 5:1 to 2:1.

[0019] From the above description, it can be seen that the present invention adopts an alcohol / water-silicon-based template system, and utilizes the abundant hydroxyl groups on the alcohol to assist the silicon-based template to effectively complex and anchor metal ions, thereby enhancing the stability of the catalytic active center. Secondly, this anchoring effect can also increase the dispersion of the metal catalytic center, so that the catalyst has more catalytic active centers and improves the catalytic performance.

[0020] Furthermore, the alcohol is any one of methanol, ethanol, ethylene glycol and glycerol.

[0021] Preferably, the alcohol is ethanol or ethylene glycol.

[0022] Furthermore, the metal salt precursor includes a first type of metal salt precursor, a second type of metal salt precursor and a third type of metal salt precursor; the metal in the first type of metal salt precursor is any one of the alkaline earth metals Ba, Sr, Ca and Mg, the metal in the second type of metal salt precursor is any one of the transition metals Co, Ni and Cu, and the metal in the third type of metal salt precursor is any one of the precious metals Ru, Pd and Pt.

[0023] Preferably, the metal in the first type of metal salt precursor is Ba or Sr, the metal in the second type of metal salt precursor is Co or Ni, and the metal in the third type of metal salt precursor is Pd.

[0024] From the above description, it can be seen that the present invention uses three types of metals, namely alkaline earth metals, transition metals and precious metals to prepare metal salt precursors. After the metal salt precursors of these three types of metals are anchored on a silicon-based template under hydrothermal conditions, the lattice doping of metal species is achieved through the two steps of crystallization and calcination, thereby increasing the number of active sites and obtaining better catalytic performance.

[0025] Furthermore, the first type of metal salt precursor and the second type of metal salt precursor are both nitrates or nitrate hydrates, and the third type of metal precursor is any one of RuCl3, (NH4)2PdCl4 and (NH4)2PtCl6.

[0026] Furthermore, the mass ratio of metal to silicon-based template in the first type of metal salt precursor is 1:20~1:4, the mass ratio of metal to silicon-based template in the second type of metal salt precursor is 1:50~1:10, and the mass ratio of metal to silicon-based template in the third type of metal precursor is 1:1000~1:100.

[0027] Preferably, the mass ratio of metal to silicon-based template in the first type of metal salt precursor is 1:10-1:7, the mass ratio of metal to silicon-based template in the second type of metal salt precursor is 1:25-1:12.5, and the mass ratio of metal to silicon-based template in the third type of metal precursor is 1:400-1:200.

[0028] Furthermore, the temperature of the hydrothermal treatment is 120~220 ℃, and the time is 3~24 h.

[0029] Preferably, the temperature of the hydrothermal treatment is 150-200 °C and the time is 8-18 h.

[0030] Furthermore, the centrifugal separation and drying step is specifically as follows: after obtaining a solid product by centrifugal separation, drying the solid product in a forced air drying oven at 120° C. for 12 h.

[0031] Furthermore, the calcination temperature is 350~650°C, and the calcination time is 2~12 h.

[0032] Preferably, the calcination temperature is 450-600°C and the calcination time is 4-6 h.

[0033] Another technical solution adopted by the present invention is: a confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene, which is prepared by using the above-mentioned preparation method of the confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene.

[0034] Another technical solution adopted by the present invention is: the application of the above-mentioned confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene in the reaction of preparing hexafluoro-1,3-butadiene by continuous hydrogenation coupling of 1,1,2-trifluoro-1,2,2-trichloroethane.

[0035] From the above description, it can be seen that the confined alloy catalyst of the present invention has a long life and has a high conversion rate and selectivity when used for the continuous hydrogenation coupling reaction of 1,1,2-trifluoro-1,2,2-trichloroethane to prepare hexafluoro-1,3-butadiene.

[0036] Embodiment 1 of the present invention is: a method for preparing a confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene, the steps are as follows: 20 g of SBA-15 molecular sieve was weighed and dispersed in 400 mL of ethanol / water mixed solvent, wherein the volume ratio of ethanol to water was 5:1. Then, 3.8 g of barium nitrate, 3.95 g of cobalt nitrate hexahydrate and 0.134 g of (NH4)2PdCl4 were added thereto. The obtained solution was transferred to a hydrothermal autoclave and hydrothermally crystallized at 150 °C for 8 h. The obtained product was then centrifuged and dried in a forced air drying oven at 120 °C for 12 h. Finally, it was placed in a muffle furnace and calcined at 450 °C for 4 h to obtain the confined alloy catalyst BaCoPd@SBA-15, which was recorded as S-1.

[0037] Embodiment 2 of the present invention is: a method for preparing a confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene, the steps are as follows: 20 g of SiO2 was weighed and dispersed in 400 mL of a methanol / water mixed solvent, in which the volume ratio of methanol to water was 10:1. Then, 5.89 g of calcium nitrate tetrahydrate, 1.52 g of copper nitrate trihydrate and 0.041 g of RuCl3 were added thereto. The resulting solution was transferred to a hydrothermal autoclave and hydrothermally crystallized at 120 °C for 3 h. The product was then centrifuged and dried in a forced air drying oven at 120 °C for 12 h. Finally, it was placed in a muffle furnace and calcined at 350 °C for 2 h to obtain the confined alloy catalyst CaCuRu@SiO2, which was recorded as S-2.

[0038] Embodiment 3 of the present invention is: a method for preparing a confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene, the steps are as follows: 10 g of ZSM-5 molecular sieve was weighed and dispersed in 400 mL of a glycerol / water mixed solvent, wherein the volume ratio of glycerol to water was 1:1. Subsequently, 26.4 g of magnesium nitrate hexahydrate, 3.8 g of copper nitrate trihydrate and 0.227 g of (NH4)2PtCl6 were added thereto. The resulting solution was transferred to a hydrothermal autoclave and hydrothermally crystallized at 220 °C for 24 h. Subsequently, the product was centrifuged and dried in a forced air drying oven at 120 °C for 12 h. Finally, it was placed in a muffle furnace and calcined at 650 °C for 12 h to obtain the confined alloy catalyst MgCuPt@ZSM-5, which was recorded as S-3.

[0039] Embodiment 4 of the present invention is: a method for preparing a confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene, the steps are as follows: 20 g of silicalite-1 molecular sieve was weighed and dispersed in 400 mL of ethylene glycol / water mixed solvent, wherein the volume ratio of ethylene glycol to water was 2:1. Then, 6.9 g of strontium nitrate, 7.93 g of nickel nitrate hexahydrate and 0.267 g of (NH4)2PdCl4 were added thereto. The obtained solution was transferred to a hydrothermal autoclave and hydrothermally crystallized at 200 °C for 18 h. The obtained product was then centrifuged and dried in a forced air drying oven at 120 °C for 12 h. Finally, it was placed in a muffle furnace and calcined at 600 °C for 6 h to obtain the confined alloy catalyst SrNiPd@silicalite-1, recorded as S-4.

[0040] Embodiment 5 of the present invention is: a method for preparing a confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene, the steps are as follows: 20 g of SBA-15 molecular sieve was weighed and dispersed in 400 mL of ethanol / water mixed solvent, wherein the volume ratio of ethanol to water was 4:1. Then, 4.2 g of barium nitrate, 4.95 g of nickel nitrate hexahydrate and 0.16 g of (NH4)2PdCl4 were added thereto. The obtained solution was transferred to a hydrothermal autoclave and hydrothermally crystallized at 180 °C for 10 h. The obtained product was then centrifuged and dried in a forced air drying oven at 120 °C for 12 h. Finally, it was placed in a muffle furnace and calcined at 500 °C for 5 h to obtain the confined alloy catalyst BaNiPd@SBA-15, denoted as S-5.

[0041] Embodiment 6 of the present invention is: a method for preparing a confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene, the steps are as follows: 20 g of silicalite-1 molecular sieve was weighed and dispersed in 400 mL of ethanol / water mixed solvent, wherein the volume ratio of ethanol to water was 3:1. Then, 6.04 g of strontium nitrate, 6.58 g of cobalt nitrate hexahydrate and 0.214 g of (NH4)2PdCl4 were added thereto. The obtained solution was transferred to a hydrothermal autoclave and hydrothermally crystallized at 160 °C for 12 h. The obtained product was then centrifuged and dried in a forced air drying oven at 120 °C for 12 h. Finally, it was placed in a muffle furnace and calcined at 550 °C for 4 h to obtain the confined alloy catalyst SrCoPd@silicalite-1, recorded as S-6.

[0042] Embodiment 7 of the present invention is: a method for preparing a confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene, the steps are as follows: 20 g of SBA-15 molecular sieve was weighed and dispersed in 400 mL of ethanol / water mixed solvent, wherein the volume ratio of ethanol to water was 2:1. Then, 3.8 g of barium nitrate, 7.93 g of nickel nitrate hexahydrate and 0.187 g of (NH4)2PdCl4 were added thereto. The obtained solution was transferred to a hydrothermal autoclave and hydrothermally crystallized at 200 °C for 16 h. The obtained product was then centrifuged and dried in a forced air drying oven at 120 °C for 12 h. Finally, it was placed in a muffle furnace and calcined at 600 °C for 5 h to obtain the confined alloy catalyst BaNiPd@SBA-15, which was recorded as S-7.

[0043] Embodiment 8 of the present invention is: a method for preparing a confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene, the steps are as follows: 20 g of silicalite-1 molecular sieve was weighed and dispersed in 400 mL of ethylene glycol / water mixed solvent, wherein the volume ratio of ethylene glycol to water was 3:1. Then, 4.83 g of strontium nitrate, 7.9 g of cobalt nitrate hexahydrate and 0.16 g of (NH4)2PdCl4 were added thereto. The obtained solution was transferred to a hydrothermal autoclave and hydrothermally crystallized at 190 °C for 8 h. The obtained product was then centrifuged and dried in a forced air drying oven at 120 °C for 12 h. Finally, it was placed in a muffle furnace and calcined at 500 °C for 6 h to obtain the confined alloy catalyst SrCoPd@silicalite-1, recorded as S-8.

[0044] Embodiment 9 of the present invention provides 8 confined alloy catalysts synthesized by the preparation methods of embodiments 1 to 8 respectively.

[0045] Embodiment 10 of the present invention is: Application of a confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene in the reaction of continuous hydrogenation coupling of 1,1,2-trifluoro-1,2,2-trichloroethane to prepare hexafluoro-1,3-butadiene, the steps are as follows: The confined alloy catalysts synthesized in Examples 1 to 8 were used in the continuous hydrogenation coupling reaction of 1,1,2-trifluoro-1,2,2-trichloroethane (CF2ClCFCl2, CFC-113) to prepare hexafluoro-1,3-butadiene, and the catalyst activity evaluation was carried out in a fixed bed reactor at atmospheric pressure.

[0046] The reaction for preparing hexafluoro-1,3-butadiene is as follows: the reaction tube of the tubular reactor is a stainless steel tube with an inner diameter of 20 mm and a length of 1000 mm. 10 ml of catalyst particles are measured and loaded into the tubular reactor. The catalyst particle size is 20-40 mesh. After the catalyst is loaded, 50 mL / min of N2 is introduced and the temperature is raised to 300 °C for dehydration and activation for 2 h. After the dehydration and activation are completed, the temperature is raised to 500 °C, and then a mixed gas of CFC-113 and H2 is introduced. The volume ratio of CFC-113 to H2 is 1:8, and the catalytic reaction space velocity is 700 h -1 The reaction pressure is normal pressure. The tail gas generated by the reaction is washed with alkali, washed with water, dried, and then analyzed and detected online by gas chromatography.

[0047] Table 1 lists the catalysts prepared in Examples 1 to 8 according to the above process conditions (i.e., normal pressure, 500 °C reaction temperature, 700 h -1 The catalyst activity test results of the reaction for 30 h at 37 °C (1.3 °F) were taken as indicators, with the conversion rate of CFC-113 and the selectivity of hexafluoro-1,3-butadiene as the indicators.

[0048] Table 1

[0049] It can be seen from the activity results in Table 1 that when the confined alloy catalyst provided by the method of the present invention is used for the continuous hydrogenation coupling reaction of 1,1,2-trifluoro-1,2,2-trichloroethane to prepare hexafluoro-1,3-butadiene, it has a high conversion rate and selectivity, and the catalyst life is long.

[0050] In summary, the preparation method of the confined alloy catalyst provided by the present invention has the following advantages: 1) Using an alcohol / water-silicon-based template system, the alcohol has abundant hydroxyl groups, which can assist the silicon-based template in effectively complexing and anchoring metal ions. This anchoring effect can not only enhance the stability of the catalytic active center, but also improve the dispersion of the metal catalytic center, thereby improving the catalytic performance.

[0051] 2) Three specific metals are anchored on the silicon-based template under hydrothermal conditions, and then the lattice doping of metal species is achieved through crystallization and calcination to increase the number of active sites and thus obtain better catalytic performance.

[0052] 3) The catalyst prepared by the present invention is easy to prepare repeatedly and is suitable for scaled-up preparation. The catalyst is easy to regenerate and can be reused, has high economic benefits, and has excellent industrial application prospects.

[0053] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the specification of the present invention, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing a confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene, characterized in that: The method comprises the following steps: adding a silicon-based template, a solvent and a metal salt precursor into a hydrothermal kettle, subjecting the product to hydrothermal treatment for a period of time, then subjecting the obtained product to centrifugal separation and drying, and finally placing the product into a muffle furnace for calcination to obtain a confined alloy catalyst.

2. The method for preparing a confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene according to claim 1, characterized in that: The silicon-based template is any one of nano-SiO2, ZSM-5 molecular sieve, silicalite-1 molecular sieve and SBA-15 molecular sieve.

3. The method for preparing a confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene according to claim 1, characterized in that: The solvent is an alcohol / water mixed solvent, and the volume ratio of alcohol to water in the solvent is 10:1 to 1:

1.

4. The method for preparing a confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene according to claim 1, characterized in that: The metal salt precursor includes a first type of metal salt precursor, a second type of metal salt precursor and a third type of metal salt precursor; the metal in the first type of metal salt precursor is any one of the alkaline earth metals Ba, Sr, Ca and Mg, the metal in the second type of metal salt precursor is any one of the transition metals Co, Ni and Cu, and the metal in the third type of metal salt precursor is any one of the precious metals Ru, Pd and Pt.

5. The method for preparing a confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene according to claim 4, characterized in that: The first type of metal salt precursor and the second type of metal salt precursor are both nitrates or nitrate hydrates, and the third type of metal precursor is any one of RuCl3, (NH4)2PdCl4 and (NH4)2PtCl6.

6. The method for preparing a confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene according to claim 4, characterized in that: The mass ratio of metal to silicon-based template in the first type of metal salt precursor is 1:20-1:4, the mass ratio of metal to silicon-based template in the second type of metal salt precursor is 1:50-1:10, and the mass ratio of metal to silicon-based template in the third type of metal precursor is 1:1000-1:

100.

7. The method for preparing a confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene according to claim 1, characterized in that: The temperature of the hydrothermal treatment is 120-220°C, and the time is 3-24 hours.

8. The method for preparing a confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene according to claim 1, characterized in that: The calcination temperature is 350-650°C and the calcination time is 2-12 h.

9. A confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene, characterized in that: The catalyst is prepared by the method for preparing a confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene as described in any one of claims 1 to 8.

10. Use of the confined alloy catalyst for the synthesis of hexafluoro-1,3-butadiene as claimed in claim 9 in the reaction of preparing hexafluoro-1,3-butadiene by continuous hydrogenation coupling of 1,1,2-trifluoro-1,2,2-trichloroethane.

Images