Method for producing 2,3,3,3-tetrafluoropropene from 1,1,2,3,3,3-hexafluoropropylene

Abstract

Disclosed in the present invention is a method for producing 2,3,3,3-tetrafluoropropene from 1,1,2,3,3,3-hexafluoropropene, comprising: (a) introducing 1,1,2,3,3,3-hexafluoropropene and hydrogen into a first reactor for a catalytic reaction to obtain a first reaction product; (b) separating the first reaction product to obtain 1,1,1,2,3,3-hexafluoropropane; (c) introducing 1,1,1,2,3,3-hexafluoropropane into a second reactor for a catalytic reaction to obtain a second reaction product; (d) separating the second reaction product to obtain 1,2,3,3,3-pentafluoropropene; (e) introducing 1,2,3,3,3-pentafluoropropene and hydrogen into a third reactor for a catalytic reaction to obtain a third reaction product; (f) separating the third reaction product to obtain 1,1,1,2,3-pentafluoropropane; (g) introducing 1,1,1,2,3-pentafluoropropane into a fourth reactor for a catalytic reaction to obtain a fourth reaction product; and (h) separating the fourth reaction product to obtain a final product of 2,3,3,3-tetrafluoropropene. The present invention has the advantages of being simple in process, low in cost, high in efficiency, green, and environmentally friendly.

Description

A method for producing 2,3,3,3-tetrafluoropropylene from 1,1,2,3,3,3-hexafluoropropylene Technical Field

[0001] The present invention relates to a method for preparing fluorine-containing olefins, and in particular to a method for producing 2,3,3,3-tetrafluoropropylene from 1,1,2,3,3,3-hexafluoropropylene. Background Art

[0002] On September 15, 2021, China officially announced its accession to the Kigali Amendment. The Kigali Amendment aims to regulate HFCs (third-generation refrigerants, primarily hydrofluorocarbons) worldwide, requiring A5 countries, including China, to freeze HFC production and consumption in 2024, begin reducing HFCs in 2029, and achieve an 80% reduction by 2045. Therefore, the development and research of green, efficient, and low-GWP refrigeration technologies is urgent.

[0003] Fourth-generation refrigerants primarily refer to fluorinated olefins (HFOs), which boast advantages such as zero ODP and extremely low GWP. A representative product is 2,3,3,3-tetrafluoropropene (HFO-1234yf, also known as R1234yf). HFO-1234yf has a boiling point of -29°C, an ODP of 0, a GWP of 4, and an atmospheric lifetime of 11 days. It can be used as a refrigerant to replace HFC-134a in automotive air conditioning systems. Three main methods for the preparation of HFO-1234yf have promising industrial applications: the 3,3,3-trifluoropropene method, the hexafluoropropylene (HFP) method, and the 1,1,2,3-tetrachloropropene (TCP) method. The HFP method involves four steps: two hydrogenation steps and two dehydrofluorination steps. HFO-1234yf is readily available, produces few byproducts, and is a simple process, making it widely used in research and application.

[0004] For example, CN107011114A discloses a method for preparing HFO-1234yf from 1,1,2,3,3,3-hexafluoropropylene: (1) reacting HFP with hydrogen in the presence of a catalyst to produce 1,1,1,2,3,3-hexafluoropropane (HFC-236ea); (2) reacting HFC-236ea with an alkaline aqueous solution to obtain 1,2,3,3,3-pentafluoropropylene (HFO-1225ye); (3) HFO-1225ye is reacted with hydrogen in the presence of a catalyst to produce 1,1,1,2,3-pentafluoropropane (HFC-245eb); (4) HFC-245eb is purified to remove compounds having a boiling point that differs from that of HFO-1234yf by ±10°C; and (5) HFC-245eb is reacted with an alkaline aqueous solution and purified to obtain HFO-1234yf. Although the liquid phase dehydrofluorination method is easy to operate, it has a long operating cycle, high product energy consumption, and high investment costs.

[0005] For example, CN101553453A, CN102026947A, and CN102267869A disclose the production of HFO-1234yf from hexafluoropropylene via a four-step reaction process: hydrogenation, dehydrofluorination, further hydrogenation, and dehydrofluorination. However, existing technologies suffer from numerous and complex steps, significant equipment investment, high separation costs, high energy consumption, and significant emissions of waste.

[0006] Summary of the Invention

[0007] In view of the deficiencies in the prior art, the present invention provides a method for producing 2,3,3,3-tetrafluoropropylene from 1,1,2,3,3,3-hexafluoropropylene, which has the advantages of simple process, high efficiency, low cost and environmental protection.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for producing 2,3,3,3-tetrafluoropropylene from 1,1,2,3,3,3-hexafluoropropylene, comprising the following steps:

[0009] (a) introducing 1,1,2,3,3,3-hexafluoropropylene and hydrogen into a first reactor, reacting them under the action of a first catalyst to obtain a first reaction product;

[0010] (b) passing the first reaction product into a first separation unit for separation to obtain 1,1,1,2,3,3-hexafluoropropane and unreacted hydrogen, and recycling the unreacted hydrogen to the first reactor;

[0011] (c) introducing the 1,1,1,2,3,3-hexafluoropropane obtained in step (b) into a second reactor and reacting in the presence of a second catalyst to obtain a second reaction product;

[0012] (d) passing the second reaction product into a second separation unit for separation to obtain 1,2,3,3,3-pentafluoropropene, hydrogen fluoride and unreacted 1,1,1,2,3,3-hexafluoropropane, and recycling the unreacted 1,1,1,2,3,3-hexafluoropropane to the second reactor;

[0013] (e) introducing the 1,2,3,3,3-pentafluoropropylene obtained in step (d) and hydrogen into a third reactor, reacting them under the action of a third catalyst to obtain a third reaction product;

[0014] (f) passing the third reaction product into a third separation unit for separation to obtain 1,1,1,2,3-pentafluoropropane and unreacted hydrogen, and recycling the unreacted hydrogen to the third reactor;

[0015] (g) introducing the 1,1,1,2,3-pentafluoropropane obtained in step (f) into a fourth reactor and reacting in the presence of a fourth catalyst to obtain a fourth reaction product;

[0016] (h) passing the fourth reaction product into a fourth separation unit for separation to obtain final products of 2,3,3,3-tetrafluoropropene, hydrogen fluoride and unreacted 1,1,1,2,3-pentafluoropropane, and recycling the unreacted 1,1,1,2,3-pentafluoropropane to the fourth reactor.

[0017] As a preferred embodiment of the present invention, the first catalyst has Pd and / or Pt as the main components, and one or more selected from Ni, Fe, Cu, and Al as auxiliary components. The main components and auxiliary components are loaded on a carrier, and the carrier is one or more of activated carbon, titanium dioxide, aluminum oxide, and silicon dioxide. The loading amount of the main component is 0.01 to 0.3 wt% (wt%, mass percentage), and the loading amount of the auxiliary component is 0.001 to 0.5 wt%.

[0018] As a preferred embodiment of the present invention, the second catalyst has chromium as the main component and one or more selected from Mg, Zn, Co, and Fe as auxiliary components. The main component and auxiliary components are loaded on γ-Al2O3 and / or AlF3 carriers, and the loading amount of chromium is 5 to 20 wt%, and the loading amount of the auxiliary components is 1 to 5 wt%.

[0019] As a preferred embodiment of the present invention, the third catalyst is composed of Pd and / or Pt as the main components and one or more selected from Ni, Au, and Al as auxiliary components. The main components and auxiliary components are loaded on a carrier, and the carrier is one or more of activated carbon, titanium dioxide, aluminum oxide, and silicon dioxide. The loading amount of the main component is 0.08 to 0.5 wt%, and the loading amount of the auxiliary component is 0.001 to 0.5 wt%.

[0020] As a preferred embodiment of the present invention, the fourth catalyst has chromium as the main component and one or more selected from Mg, Zn, In, and Ga as auxiliary components. The main component and auxiliary components are loaded on γ-Al2O3 and / or AlF3 carriers, and the loading amount of the chromium is 5 to 15 wt%, and the loading amount of the auxiliary components is 0.5 to 3 wt%.

[0021] As a preferred embodiment of the present invention, the molar ratio of 1,1,2,3,3,3-hexafluoropropylene to hydrogen in step (a) is 1:5-30, the reaction temperature is 80-200°C, the pressure is 0.1-1.5 MPa, and the space velocity is 300-2000h -1 .

[0022] As a preferred embodiment of the present invention, the reaction temperature in step (c) is 150-400°C, the pressure is 0.1-1.5 MPa, and the space velocity is 30-1000 h -1 .

[0023] As a preferred embodiment of the present invention, the molar ratio of 1,2,3,3,3-pentafluoropropylene to hydrogen in step (e) is 1:10-20, the reaction temperature is 80-200°C, the pressure is 0.1-1.5 MPa, and the space velocity is 300-2000h -1 .

[0024] As a preferred embodiment of the present invention, the reaction temperature in step (g) is 150-400°C, the pressure is 0.1-1.5 MPa, and the space velocity is 30-1000 h -1 .

[0025] As a preferred embodiment of the present invention, the first separation unit and the third separation unit adopt membrane separation; the second separation unit and the fourth separation unit adopt extractive distillation.

[0026] The present invention realizes the production of HFO-1234yf using HFP as raw material through four reactors. The first reactor mainly undergoes HFP hydrogenation reaction to obtain 1,1,1,2,3,3-hexafluoropropane (HFC-236ea), the second reactor mainly undergoes HFC-236ea defluorination reaction to obtain 1,2,3,3,3-pentafluoropropylene (HFO-1225ye), the third reactor mainly undergoes HFO-1225ye hydrogenation reaction to obtain 1,1,1,2,3-pentafluoropropane (HFC-245eb), and the fourth reactor mainly undergoes HFC-245eb defluorination reaction to obtain HFO-1234yf. The main equations are as follows: CF2=CFCF3(HFP)+H2→CF2HCHFCF3(HFC-236ea) CF2HCHFCF3(HFC-236ea)→CHF=CFCF3(HFO-1225ye)+HF CHF=CFCF3(HFO-1225ye)+H2→CH2FCHFCF3(HFC-245eb) CH2FCHFCF3(HFC-245eb)→CH2=CFCF3(HFO-1234yf)+HF

[0027] The boiling points of some substances in the present invention are as follows:

[0028] In the present invention, the first reactor can be a gas phase reactor, HFP and H2 are introduced into the first reactor to obtain a mixture containing HFC-236ea, H2, etc., and the mixture is introduced into the first separation unit; the first separation unit uses at least one membrane separator, H2 is separated from the top, H2 is returned to the first reactor for continued use, and HFC-236ea at the bottom is introduced into the second reactor; dehydrofluorination reaction is carried out in the second reactor to obtain a mixture containing HFO-1225ye, HF and HFC-236ea, and the mixture is introduced into the second separation unit; the second separation unit uses two or more extractive distillation towers, the extractant can be water, HF is first removed, and then the mixture of HFO-1225ye and HFC-236ea is separated, and HFC-236ea is returned from the bottom of the tower to the second reactor for continued reaction; HFO-1225ye is introduced into The third reactor undergoes a hydrogenation reaction with H2 in the third reactor to obtain a mixture containing HFC-245eb, H2, etc., and the mixture is passed into a third separation unit; the third separation unit uses at least one membrane separator to separate H2 at the top, which is returned to the third reactor for continued use, and the HFC-245eb at the bottom is passed into a fourth reactor; a dehydrofluorination reaction is carried out in the fourth reactor to obtain a mixture containing HFO-1234yf, HF and a small amount of HFC-245eb, and the mixture is passed into a fourth separation unit. The fourth separation unit uses two or more extractive distillation towers, and the extractant can be water. The HF is first removed, and then the mixture of HFO-1234yf and HFC-245eb is separated. The HFC-245eb is returned from the bottom of the tower to the fourth reactor for continued reaction, and the target product HFO-1234yf is obtained at the top.

[0029] In the present invention, the first reactor is the HFP hydrogenation reaction, which is a highly exothermic reaction. The reaction temperature has a great influence on the activity of the catalyst and the selectivity of the product. The increase in reaction temperature helps to improve the activity of the catalyst. However, since HFP hydrogenation is relatively easy to carry out, the conversion rate of HFP and the selectivity of HFC-236ea can reach 100% at a lower temperature. Considering the industrial application value of the catalyst, while ensuring the high activity of the catalyst, the reaction temperature should be lowered as much as possible to reduce energy consumption. Therefore, the reaction temperature of the first reactor is preferably 80-200°C, and the reaction temperature is more preferably 90-150°C. As the space velocity increases, the contact time between the reactants and the catalyst bed decreases, and the activity of the catalyst decreases. To ensure the complete conversion of HFP, the space velocity is preferably 300-2000h -1 , more preferably 500 to 1000 hours -1The molar ratio of H2 to HFP has a great influence on the reaction. A low molar ratio results in a low concentration of H2 in the reaction system and low catalyst activity. An increase in the molar ratio of H2 to HFP will effectively prevent the occurrence of catalyst carbon deposition, improve the selectivity and stability of the catalyst, and gradually increase the activity of the catalyst. Considering that excess H2 can take away the heat of the reaction and prevent catalyst carbon deposition, the molar ratio of HFP to H2 is selected to be 1:5 to 30, preferably 1:10 to 20.

[0030] The second reactor is a gas-phase dehydrofluorination reaction with a high temperature and a high conversion rate of HFC-236ea, but a low selectivity of the target product. Based on the performance of the catalyst and the conversion rate and selectivity verification, the reaction temperature is preferably 150-400°C, more preferably 180-300°C.

[0031] The third reactor and the fourth reactor are respectively used for HFO-1225ye hydrogenation reaction and HFC-245eb HF removal reaction, which are similar to the reactions in the first and second reactors. The reaction temperature of the third reactor is preferably 80-200°C, more preferably 90-150°C; the space velocity is preferably 300-2000h -1 , more preferably 500 to 1000 hours -1 The reaction temperature of the fourth reactor is preferably 150-400°C, more preferably 180-300°C; the space velocity is preferably 30-1000h -1 , more preferably 100 to 800 hours -1 .

[0032] The first and third reactors of the present invention are loaded with a composite catalyst of Pd and / or Pt noble metals and an auxiliary metal. If the noble metal loading is too low, the catalytic activity is insufficient. There is an optimal balance between the noble metal content and the catalyst activity. The choice of carrier is crucial for the catalyst. The hydrogenation of HFP is relatively easy. Selecting activated carbon, titanium dioxide, aluminum oxide, or silicon dioxide as the carrier, and adding auxiliary metals such as Ni, Fe, Au, Cu, and Al help to increase the dispersion of the loaded catalytically active centers, Pd and Pt, thereby producing a highly active catalyst. Experiments have shown that the noble metal loading in the first reactor is 0.01-0.3%, and the auxiliary metal loading is 0.001-0.5%. The noble metal loading in the third reactor is 0.08-0.5%, and the auxiliary metal loading is 0.001-0.5%.

[0033] The catalyst used in the second and fourth reactors of the present invention can be a catalyst known in the art containing chromium as the active component, with a carrier of γ-Al2O3 and / or AlF3, and one or more auxiliary metals selected from Mg, Zn, Co, Fe, In, and Ga added to increase the dispersion of the chromium. The catalyst can be prepared using conventional methods in the art, such as mixing nitrates of chromium and the auxiliary metal in a specific ratio to form a dilute solution of a certain concentration, adding a precipitant to react, followed by filtration, washing, drying, calcining, granulation, and tableting to form a precursor, which is then fluorinated to produce the catalyst. Catalyst pretreatment can be performed in other reactors.

[0034] Compared with the prior art, the present invention has the following advantages:

[0035] 1. Low cost. The membrane separation technology used in the present invention has high separation efficiency, no phase change, no chemical reaction, small size, low energy consumption and easy operation. In addition, the raw materials HFP and H2 are widely available, which significantly reduces the cost of raw materials in the production process.

[0036] 2. The process is simple and efficient. The four-step reaction of the present invention can all be completed in the gas phase. The reaction efficiency is improved by optimizing the reaction process, catalyst and material ratio, reaction temperature and pressure and other parameters. The reaction temperature and reaction pressure are relatively low, the reaction conditions are mild and easy to control, and the process is significantly simplified.

[0037] 3. Green and environmentally friendly, with less three wastes. The unreacted raw materials and intermediate products of the present invention can be recycled into the reactor to continue the reaction, which significantly reduces the discharge of three wastes. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] FIG1 is a process flow chart of the present invention.

[0039] As shown in the figure: 1 is the first reactor, 2 is the second reactor, 3 is the third reactor, 4 is the fourth reactor, 5 is the first membrane separator, 6-1 is the first extractive distillation tower, 6-2 is the second extractive distillation tower, 7 is the second membrane separator, 8-1 is the third extractive distillation tower, and 8-2 is the fourth extractive distillation tower. DETAILED DESCRIPTION

[0040] The process of the present invention is shown in Figure 1. Raw materials HFP and H2 are introduced into a first reactor 1 to obtain a mixture containing HFC-236ea and H2; the mixture is introduced into a first membrane separator 5, H2 is separated at the top, and H2 is returned to the first reactor 1 for continued use, and HFC-236ea at the bottom is introduced into a second reactor 2, where a dehydrofluorination reaction is carried out to obtain a mixture containing HFO-1225ye, HF and HFC-236ea, which is then introduced into a first extractive distillation tower 6-1; HF is separated at the bottom of the first extractive distillation tower 6-1, and a mixture of HFO-1225ye and HFC-236ea is separated at the top of the tower. The mixture of HFO-1225ye and HFC-236ea is introduced into a second extractive distillation tower 6-2; HFO-1225ye is obtained at the top of the second extractive distillation tower 6-2, and HFC-236ea is obtained at the bottom of the tower. HFC-236ea is returned to the second reactor 2 for continued reaction; HFO-1225ye is removed from the bottom of the first extractive distillation tower 6-1, and HFC-236ea is removed from the top of the tower. The HFC-245eb is passed into the third reactor 3, where it undergoes a hydrogenation reaction with H2 to obtain a mixture containing HFC-245eb and H2. The mixture is then passed into the second membrane separator 7. H2 is separated from the top of the second membrane separator 7 and returned to the third reactor 3 for further use. The HFC-245eb at the bottom is passed into the fourth reactor 4, where it undergoes a dehydrofluorination reaction to obtain a mixture containing HFO-1234yf, HF, and a small amount of HFC-245eb. The mixture is then passed into the third extractive distillation column 8-1. HF is separated from the bottom of the third extractive distillation column 8-1, and a mixture of HFO-1234yf and HFC-245eb is separated from the top. The mixture is then passed into the fourth extractive distillation column 8-2. The HFO-1234yf product is separated from the top of the fourth extractive distillation column 8-2, and HFC-245eb is obtained from the bottom. The HFC-245eb is then returned to the fourth reactor 4 for further reaction.

[0041] The following is a further clear and complete description of the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only part of the embodiments of the present invention, rather than all the embodiments.

[0042] Example 1

[0043] First, 200ml of Pd-Ni / C catalyst (the mass percentage of Pd is 0.01% and the mass percentage of Ni is 0.001%) is loaded into the first reactor, 300ml of Cr-Mg / γ-Al2O3 catalyst (the mass percentage of Cr is 5% and the mass percentage of Mg is 1%) is loaded into the second reactor, 200ml of Pd-Ni / C catalyst (the mass percentage of Pd is 0.08% and the mass percentage of Ni is 0.001%) is loaded into the third reactor, and 300ml of Cr-Mg / γ-Al2O3 catalyst (the mass percentage of Cr is 5% and the mass percentage of Mg is 0.5%) is loaded into the fourth reactor.

[0044] Next, heat the first reactor to 80°C, the second reactor to 150°C, the third reactor to 80°C, and the fourth reactor to 150°C. The heating rate for all four reactors was 1°C / min from room temperature to 80°C, and 0.5°C / min above 80°C. After heating, dry the reactors with nitrogen for 2 hours.

[0045] Then the feeding reaction was started, HFP and H2 were mixed and introduced, and the reaction conditions of each reactor were shown in Table 1.

[0046] The mixtures at the outlets of the first reactor, the second reactor, the third reactor and the fourth reactor were sampled and analyzed by gas chromatography. The organic matter compositions thereof are shown in Table 2.

[0047] Table 1 Reaction conditions of each reactor in Example 1

[0048] Table 2 Composition of each reactor outlet in Example 1

[0049] Example 2

[0050] First, 200ml of Pd-Fe / TiO2 catalyst (the mass percentage of Pd is 0.1% and the mass percentage of Fe is 0.01%) is loaded into the first reactor, 300ml of Cr-Zn / AlF3 catalyst (the mass percentage of Cr is 10% and the mass percentage of Zn is 2%) is loaded into the second reactor, 200ml of Pd-Fe / TiO2 catalyst (the mass percentage of Pd is 0.2% and the mass percentage of Ni is 0.01%) is loaded into the third reactor, and 300ml of Cr-Zn / AlF3 catalyst (the mass percentage of Cr is 8% and the mass percentage of Zn is 1%) is loaded into the fourth reactor.

[0051] Next, heat the first reactor to 100°C, the second reactor to 200°C, the third reactor to 100°C, and the fourth reactor to 200°C. The heating rate for all four reactors was 1°C / min from room temperature to 150°C, and 0.5°C / min above 150°C. After heating all four reactors, dry them with nitrogen for 2 hours.

[0052] Then, the feeding reaction was started, and hexafluoropropylene and H2 were mixed and introduced. The reaction conditions of each reactor are shown in Table 3.

[0053] The mixtures at the outlets of the first reactor, the second reactor, the third reactor and the fourth reactor were sampled and analyzed by gas chromatography. The organic matter compositions thereof are shown in Table 4.

[0054] Table 3 Reaction conditions of each reactor in Example 2

[0055] Table 4 Reactor outlet composition in Example 2

[0056] Example 3

[0057] First, 200ml of Pd-Cu / Al2O3 catalyst (the mass percentage of Pd is 0.3% and the mass percentage of Cu is 0.1%) is loaded into the first reactor, 300ml of Cr-Co / γ-Al2O3 catalyst (the mass percentage of Cr is 15% and the mass percentage of Co is 4%) is loaded into the second reactor, 200ml of Pd-Au / Al2O3 catalyst (the mass percentage of Pd is 0.5% and the mass percentage of Au is 0.1%) is loaded into the third reactor, and 300ml of Cr-In / γ-Al2O3 catalyst (the mass percentage of Cr is 12% and the mass percentage of In is 2%) is loaded into the fourth reactor.

[0058] Next, heat the first reactor to 150°C, the second reactor to 300°C, the third reactor to 150°C, and the fourth reactor to 300°C. The heating rate for all four reactors was 1°C / min from room temperature to 150°C, and 0.5°C / min above 150°C. After heating all four reactors, dry them with nitrogen for 2 hours.

[0059] Then, the feeding reaction was started, and hexafluoropropylene and H2 were mixed and introduced. The reaction conditions of each reactor are shown in Table 5.

[0060] The mixtures at the outlets of the first reactor, the second reactor, the third reactor and the fourth reactor were sampled and analyzed by gas chromatography. The organic matter compositions thereof are shown in Table 6.

[0061] Table 5 Reaction conditions of each reactor in Example 3

[0062] Table 6 Composition of each reactor outlet in Example 3

[0063] Example 4

[0064] First, 200ml of Pt-Al / SiO2 catalyst (the mass percentage of Pt is 0.2%, and the mass percentage of Al is 0.5%) is loaded into the first reactor, 300ml of Cr-Fe / AlF3 catalyst (the mass percentage of Cr is 20%, and the mass percentage of Fe is 5%) is loaded into the second reactor, 200ml of Pt-Al / SiO2 catalyst (the mass percentage of Pt is 0.3%, and the mass percentage of Al is 0.5%) is loaded into the third reactor, and 300ml of Cr-Ga / AlF3 catalyst (the mass percentage of Cr is 15%, and the mass percentage of Ga is 3%) is loaded into the fourth reactor.

[0065] Next, heat the first reactor to 200°C, the second to 400°C, the third to 200°C, and the fourth to 400°C. The heating rate for all four reactors was 1°C / min from room temperature to 150°C, and 0.5°C / min above 150°C. After heating all four reactors, dry them with nitrogen for 2 hours.

[0066] Then, the feeding reaction was started, and hexafluoropropylene and H2 were mixed and introduced. The reaction conditions of each reactor are shown in Table 7.

[0067] The mixtures at the outlets of the first reactor, the second reactor, the third reactor and the fourth reactor were sampled and analyzed by gas chromatography. The organic matter compositions thereof are shown in Table 8.

[0068] Table 7 Reaction conditions of each reactor in Example 4

[0069] Table 8 Composition of each reactor outlet in Example 4

Claims

1. A method for producing 2,3,3,3-tetrafluoropropene from 1,1,2,3,3,3-hexafluoropropene, characterized in that, Comprising the following steps: (a) Introduce 1,1,2,3,3,3-hexafluoropropene and hydrogen into a first reactor, and react under the action of a first catalyst to obtain a first reaction product; (b) Introduce the first reaction product into a first separation unit for separation to obtain 1,1,1,2,3,3-hexafluoropropane and unreacted hydrogen, and recycle the unreacted hydrogen to the first reactor; (c) Introduce the 1,1,1,2,3,3-hexafluoropropane obtained in step (b) into a second reactor, and react under the action of a second catalyst to obtain a second reaction product; (d) Introduce the second reaction product into a second separation unit for separation to obtain 1,2,3,3,3-pentafluoropropene, hydrogen fluoride and unreacted 1,1,1,2,3,3-hexafluoropropane, and recycle the unreacted 1,1,1,2,3,3-hexafluoropropane to the second reactor; (e) Introduce the 1,2,3,3,3-pentafluoropropene and hydrogen obtained in step (d) into a third reactor, and react under the action of a third catalyst to obtain a third reaction product; (f) Introduce the third reaction product into a third separation unit for separation to obtain 1,1,1,2,3-pentafluoropropane and unreacted hydrogen, and recycle the unreacted hydrogen to the third reactor; (g) Introduce the 1,1,1,2,3-pentafluoropropane obtained in step (f) into a fourth reactor, and react under the action of a fourth catalyst to obtain a fourth reaction product; (h) Introduce the fourth reaction product into a fourth separation unit for separation to obtain the final product 2,3,3,3-tetrafluoropropene, hydrogen fluoride and unreacted 1,1,1,2,3-pentafluoropropane, and recycle the unreacted 1,1,1,2,3-pentafluoropropane to the fourth reactor.

2. The method for producing 2,3,3,3-tetrafluoropropene from 1,1,2,3,3,3-hexafluoropropene according to claim 1, characterized in that, The first catalyst has Pd and / or Pt as the main component, and one or more selected from Ni, Fe, Cu, and Al as the auxiliary component. The main component and the auxiliary component are supported on a carrier, and the carrier is one or several of activated carbon, titanium dioxide, alumina, and silica. The loading amount of the main component is 0.01 - 0.3 wt%, and the loading amount of the auxiliary component is 0.001 - 0.5 wt%.

3. The method for producing 2,3,3,3-tetrafluoropropene from 1,1,2,3,3,3-hexafluoropropene according to claim 1, characterized in that, The second catalyst has chromium as the main component, and one or more selected from Mg, Zn, Co, and Fe as the auxiliary component. The main component and the auxiliary component are supported on a γ-Al2O3 and / or AlF3 carrier. The loading amount of chromium is 5 - 20 wt%, and the loading amount of the auxiliary component is 1 - 5 wt%.

4. The method for producing 2,3,3,3-tetrafluoropropene from 1,1,2,3,3,3-hexafluoropropene according to claim 1, characterized in that, The third catalyst has Pd and / or Pt as the main component, and one or more selected from Ni, Au, and Al as the auxiliary component. The main component and the auxiliary component are supported on a carrier, and the carrier is one or more of activated carbon, titanium dioxide, alumina, and silica. The loading amount of the main component is 0.08 - 0.5 wt%, and the loading amount of the auxiliary component is 0.001 - 0.5 wt%.

5. The method for producing 2,3,3,3-tetrafluoropropene from 1,1,2,3,3,3-hexafluoropropene according to claim 1, characterized in that, The fourth catalyst described above has chromium as the main component and one or more selected from Mg, Zn, In, and Ga as auxiliary components. The main component and the auxiliary components are supported on a γ-Al2O3 and / or AlF3 carrier. The loading amount of chromium is 5-15 wt%, and the loading amount of the auxiliary components is 0.5-3 wt%.

6. The method for producing 2,3,3,3-tetrafluoropropene from 1,1,2,3,3,3-hexafluoropropene according to claim 1, characterized in that, The molar ratio of 1,1,2,3,3,3-hexafluoropropene to hydrogen described in step (a) is 1:5 to 30, the reaction temperature is 80 to 200 °C, the pressure is 0.1 to 1.5 MPa, and the space velocity is 300 to 2000 h -1 .

7. The method for producing 2,3,3,3-tetrafluoropropene from 1,1,2,3,3,3-hexafluoropropene according to claim 1, characterized in that, The temperature of the reaction described in step (c) is 150 to 400 °C, the pressure is 0.1 to 1.5 MPa, and the space velocity is 30 to 1000 h -1 .

8. The method for producing 2,3,3,3-tetrafluoropropene from 1,1,2,3,3,3-hexafluoropropene according to claim 1, characterized in that, In step (e), the molar ratio of 1,2,3,3,3-pentafluoropropene to hydrogen is 1:10 to 20, the reaction temperature is 80 to 200 °C, the pressure is 0.1 to 1.5 MPa, and the space velocity is 300 to 2000 h -1 .

9. The method for producing 2,3,3,3-tetrafluoropropene from 1,1,2,3,3,3-hexafluoropropene according to claim 1, characterized in that, The temperature of the reaction described in step (g) is 150 to 400 °C, the pressure is 0.1 to 1.5 MPa, and the space velocity is 30 to 1000 h -1 .

10. The method for producing 2,3,3,3-tetrafluoropropene from 1,1,2,3,3,3-hexafluoropropene according to claim 1, characterized in that, The first separation unit and the third separation unit use membrane separation; the second separation unit and the fourth separation unit use extractive distillation.

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