Method for co-producing HFO-1234yf and HFO-1234ze

Abstract

The invention provides a method for co-producing HFO-1234yf and HFO-1234ze. The method comprises the following steps: (1) reacting dichloroethylene with trifluoromethane under the action of a first catalyst to prepare trifluorodichloropropane; (2) carrying out gas-phase dehydrochlorination reaction on the trifluorodichloropropane under the action of a second catalyst to generate trifluorochloropropene; and (3) the trifluorochloropropene and anhydrous hydrogen fluoride are subjected to a gas phase fluorination reaction under the action of a third catalyst, and HFO-1234yf and HFO-1234ze are generated. By optimizing a reaction path and a catalyst system, efficient co-production of HFO-1234yf and HFO-1234ze is realized, and the method has the advantages of mild reaction conditions, high product selectivity and the like, and is suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the fields of refrigerants, foaming agents, and fluorinated compounds, and in particular to a method for co-producing HFO-1234yf and HFO-1234ze. Background Technology

[0002] Hydrofluoroolefins (HFOs), as the fourth generation of refrigerants, have zero ozone depletion potential (ODP) and extremely low global warming potential (GWP). With the entry into force of the Kigali Amendment to the Montreal Protocol, the world is accelerating the phase-out of high-GWP hydrofluorocarbons (HFCs), making them an ideal alternative to HFCs, and market demand is surging.

[0003] Among them, 2,3,3,3-tetrafluoropropylene (HFO-1234yf) and 1,3,3,3-tetrafluoropropylene (HFO-1234ze) have wide applications in refrigeration, foaming, and aerosol propellants due to their excellent environmental performance and physicochemical properties.

[0004] Currently, there are various synthetic routes for HFO-1234yf and HFO-1234ze, but most suffer from problems such as expensive raw materials, cumbersome steps, and low selectivity. For example, the preparation process of HFO-1234yf often uses halopropanes or halopropylenes as raw materials. Honeywell International's route uses 1,1,1,2,3-pentachloropropane (HCC-240db) or 1,1,2,3-tetrachloropropene (HCO-1230xa) as raw materials and reacts with hydrogen fluoride. DuPont's disclosed HFO-1234yf synthesis technologies involve multiple steps using halopropylenes as raw materials, resulting in complex processes. Daikin Industries, Ltd. has developed a method using chlorinated alkanes or chlorinated olefins reacting with fluorinating agents at specific molar ratios. Zhejiang Sanmei Chemical Co., Ltd.'s patent CN109438170B discloses a method for preparing HFO-1234yf using 2-chloro-1,1-difluoroethylene and chlorofluoromethane as raw materials, but the raw material 2-chloro-1,1-difluoroethylene is expensive. Sinochem Modern Environmental Chemical (Xi'an) Co., Ltd.'s patent involves a method for preparing HFO-1234ze by reacting trifluoromethylacetylene with hydrogen fluoride, but the raw material is not readily available.

[0005] However, existing technologies have the following limitations: (1) High raw material costs, such as the expensive price of HCC-240db; (2) The production process is complex, and most of them require multiple reaction steps; 1,2-Dichloroethylene is a byproduct of the production process of 1,1-dichloroethylene (a VDC monomer, a raw material for the production of polyvinylidene fluoride (PVDC)), and trifluoromethane is a byproduct of the production process of difluorochloromethane (R22). Currently, these byproducts are disposed of by incineration.

[0006] In view of this, it is necessary to develop a co-production process that uses inexpensive raw materials, is simple in process, and has high selectivity. Summary of the Invention

[0007] This invention proposes a method for co-producing HFO-1234yf and HFO-1234ze, which solves the problems of high raw material costs and complex production processes in the prior art.

[0008] The technical solution of this invention is implemented as follows: A method for co-producing HFO-1234yf and HFO-1234ze includes: (1) Trifluorodichloropropane is prepared by reacting dichloroethylene with trifluoromethane in the presence of a first catalyst; (2) The trifluorodichloropropane undergoes a gas-phase dehydrochlorination reaction under the action of a second catalyst to produce trifluoromonochloropropene; (3) The trifluorochloropropene reacts with anhydrous hydrogen fluoride in the gas phase under the action of a third catalyst to produce 2,3,3,3-tetrafluoropropene (HFO-1234yf) and 1,3,3,3-tetrafluoropropene (HFO-1234ze).

[0009] In some embodiments, the molar ratio of dichloroethylene to trifluoromethane is 1:(1~3).

[0010] In some embodiments, the dichloroethylene and trifluoromethane are byproducts generated during the production processes of VDC and R22, respectively.

[0011] In some embodiments, step (1) yields 1,1,1-trifluoro-2,3-dichloropropane (HCFC-243db).

[0012] In some embodiments, the first catalyst is a transition metal complex catalyst or a cesium fluoride catalyst; the transition metal complex catalyst is adopted... Pd / Cu or Us / Cu The bimetallic system has a metal ratio of Pd:Cu≈ 1:1~10 or Ni:Cu≈ 1~3:1 (molar ratio). The ligands used are nitrogen-containing organic ligands or phosphorus-based ligands. The preferred support is TiO2 or composite metal oxide, such as CeO2-Al2O3.

[0013] In some embodiments, the amount of the first catalyst is 0.5% to 2% of the total weight of the raw materials; the total weight of the raw materials is the total weight of dichloroethylene and trifluoromethane.

[0014] In some embodiments, the reaction temperature of step (1) is 150~300℃, the reaction pressure is 1~3MPa, and the reaction time is 2~6h.

[0015] In some embodiments, the second catalyst is fluorinated chromium oxide or fluorinated aluminum oxide.

[0016] In some embodiments, the reaction temperature in step (2) is 250~400℃, the pressure is 0.1~0.5MPa, and the space velocity is 500~1500h. -1 .

[0017] In some embodiments, step (2) yields 3,3,3-trifluoro-1-chloropropene (HCFO-1233zd) and 3,3,3-trifluoro-2-chloropropene (HCFO-1233xf).

[0018] In some embodiments, the molar ratio of anhydrous hydrogen fluoride to trifluorochloropropylene is (2~5):1.

[0019] In some embodiments, the third catalyst is a Fe-Mo-Mg-F catalyst, wherein the molar ratio of Fe, Mo, and Mg is (3~4):(0.5~1):(5~7).

[0020] In some embodiments, the reaction temperature in step (3) is 280~450℃, the pressure is 0.5~2MPa, and the space velocity is 800~2000h. -1 .

[0021] In some embodiments, the steps (1), (2) or (3) further include separating and purifying the reaction products, recycling unreacted reactants, and recovering or incinerating byproducts.

[0022] The reaction equation of this invention is as follows: CHCl=CHCl + CHF 3 → CF 3 CHClCH 2 Cl When the reaction temperature is too high, the following side reactions may occur: CHCl=CHCl + CHF 3 → CHF 2 CHClCHClF The boiling point of the by-reaction product is lower than that of the main reaction product. It is separated and removed by distillation to obtain HCFC-243db. CF 3 CHClCH 2 Cl → CF 3 CH=CHCl+ HCl CF 3 CHClCH 2 Cl → CF 3 CCl=CH 2 + HCl When the reaction temperature is too low, the following side reactions may occur: CF 3 CHClCH 2 Cl → CF 3 CCl 2 CH 3 The boiling point of the by-reaction products is higher than that of the main reaction products; Hydrogen chloride and byproducts were removed by distillation to obtain HCFO-1233zd and HCFO-1233xf. CF 3 CH=CHCl+ HF → CF 3 CH=CHF+HCl CF 3 CCl=CH 2 + HF → CF 3 CF=CH 2 + HCl Hydrogen chloride and byproducts are removed by distillation, and hydrogen fluoride is separated and recovered. The products HFO-1234yf and HFO-1234ze are obtained by deacidification, drying and distillation.

[0023] Compared with the prior art, the present invention has the following advantages: (1) This invention achieves efficient co-production of HFO-1234yf and HFO-1234ze by optimizing the reaction path and catalyst system, and has the advantages of mild reaction conditions and high product selectivity, making it suitable for industrial production.

[0024] (2) This invention uses by-products generated during the production of VDC and R22 as raw materials, turning waste into treasure and being environmentally friendly. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1 Step 1: Add 3000g of 1,2-dichloroethylene and 4333.5g of trifluoromethane (molar ratio 1:2) to the reactor, and add cesium fluoride catalyst (1% of the total weight of the raw materials). React at 200℃ and 2MPa for 4 hours.

[0027] After the reaction, the main product HCFC-243db was obtained by distillation.

[0028] Step 2: The HCFC-243db obtained in Step 1 was subjected to a gas-phase dechlorination reaction at 300℃, 0.3MPa and space velocity of 1000h under the action of fluorinated chromium oxide catalyst.

[0029] After the reaction, HCFO-1233zd and HCFO-1233xf were obtained by distillation, and byproducts were removed.

[0030] Step 3: The mixture of HCFO-1233zd and HCFO-1233xf obtained in Step 2 was reacted with anhydrous hydrogen fluoride (molar ratio 1:2) in the presence of Fe-Mo-Mg-F catalyst (Fe:Mo:Mg=3.5:0.75:6) at 350℃, 1MPa and space velocity 1500h.

[0031] After the reaction, HFO-1234yf and HFO-1234ze were separated by distillation, and the unreacted material was recovered.

[0032] intermediate and product yields . Example 2

[0033] Step 1: Add 3000g of 1,2-dichloroethylene and 5416.8g of trifluoromethane (molar ratio 1:2.5) to the reactor, and add a transition metal complex catalyst (Ni / Cu, molar ratio Ni:Cu = 2:1, phosphorus-based ligand, support CeO2-Al2O3) (0.5% of the total mass of raw materials). React at 150℃ and 1MPa for 6 hours.

[0034] After the reaction, the main product HCFC-243db was obtained by distillation.

[0035] Step 2: The HCFC-243db obtained in Step 1 was subjected to a gas-phase dechlorination reaction at 250℃, 0.1MPa and space velocity of 500h under the action of alumina fluoride catalyst.

[0036] After the reaction, HCFO-1233zd and HCFO-1233xf were obtained by distillation, and byproducts were removed.

[0037] Step 3: The mixture of HCFO-1233zd and HCFO-1233xf obtained in Step 2 was reacted with anhydrous hydrogen fluoride (molar ratio 1:2.5) in the presence of Fe-Mo-Mg-F catalyst (Fe:Mo:Mg=3:0.5:5) at 280℃, 0.5MPa and space velocity 800h.

[0038] After the reaction, HFO-1234yf and HFO-1234ze were separated by distillation, and the unreacted material was recovered.

[0039] intermediate and product yields . Example 3

[0040] Step 1: Add 3000g of 1,2-dichloroethylene and 6500.2g of trifluoromethane (molar ratio 1:3) to the reactor, and add cesium fluoride catalyst (2% of the total weight of the raw materials). React at 300℃ and 3MPa for 2 hours.

[0041] After the reaction, the main product HCFC-243db was obtained by distillation.

[0042] Step 2: The HCFC-243db obtained in Step 1 was subjected to a gas-phase dechlorination reaction at 400℃, 0.5MPa and space velocity of 1500h under the action of fluorinated chromium oxide catalyst.

[0043] After the reaction, HCFO-1233zd and HCFO-1233xf were obtained by distillation, and byproducts were removed.

[0044] Step 3: The mixture of HCFO-1233zd and HCFO-1233xf obtained in Step 2 was reacted with anhydrous hydrogen fluoride (molar ratio 1:3) under the action of Fe-Mo-Mg-F catalyst (Fe:Mo:Mg=4:1:7) at 450℃, 2MPa and space velocity 2000h.

[0045] After the reaction, HFO-1234yf and HFO-1234ze were separated by distillation, and the unreacted material was recovered.

[0046] intermediate and product yields .

[0047] Example 4 Step 1: Add 3000g of 1,2-dichloroethylene and 5416.8g of trifluoromethane (molar ratio 1:2.5) to the reactor, and add a transition metal complex catalyst (Pd / Cu, molar ratio Pd:Cu = 1:5, nitrogen-containing organic ligand, supported by TiO2) (2% of the total mass of raw materials). React at 250℃ and 3MPa for 3 hours.

[0048] After the reaction, the main product HCFC-243db was obtained by distillation.

[0049] Step 2: The HCFC-243db obtained in Step 1 was subjected to a gas-phase dechlorination reaction at 350℃, 0.4MPa and space velocity of 800h under the action of fluorinated chromium oxide catalyst.

[0050] After the reaction, HCFO-1233zd and HCFO-1233xf were obtained by distillation, and byproducts were removed.

[0051] Step 3: The mixture of HCFO-1233zd and HCFO-1233xf obtained in Step 2 was reacted with anhydrous hydrogen fluoride (molar ratio 1:2.5) in the presence of a Fe-Mo-Mg-F catalyst (Fe:Mo:Mg=3.5:1.5:5.5) at 400℃, 1.5MPa and space velocity 1200h.

[0052] After the reaction, HFO-1234yf and HFO-1234ze were separated by distillation, and the unreacted material was recovered.

[0053] intermediate and product yields .

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A process for the co-production of HFO-1234yf and HFO-1234ze, characterized in that, The method comprises: (1) reacting dichloroethylene with trifluoromethane under the action of a first catalyst to prepare trifluorodichloropropane; (2) performing gas-phase dehydrochlorination reaction on the trifluorodichloropropane under the action of a second catalyst to generate trifluoromonochloropropene; (3) performing gas-phase fluorination reaction on the trifluoromonochloropropene with anhydrous hydrogen fluoride under the action of a third catalyst to generate 2,3,3,3-tetrafluoropropene (HFO-1234yf) and 1,3,3,3-tetrafluoropropene (HFO-1234ze).

2. A process for the co-production of HFO-1234yf and HFO-1234ze according to claim 1, characterized in that, The molar ratio of the dichloroethylene to the trifluoromethane is 1:(1-3).

3. A process for the co-production of HFO-1234yf and HFO-1234ze according to claim 1, characterized in that, The first catalyst is a transition metal complex catalyst or cesium fluoride catalyst; the transition metal complex catalyst is a bimetallic system of Pd / Cu or Ni / Cu, the metal ratio is Pd:Cu ≈ 1:1-10 or Ni:Cu ≈ 1-3:1 (molar ratio), the ligand used is selected from nitrogen-containing organic ligand or phosphorus-based ligand, and the carrier is preferably TiO2 or a composite metal oxide.

4. The process for the co-production of HFO-1234yf and HFO-1234ze according to claim 1, characterized in that, The amount of the first catalyst is 0.5%-2% of the total weight of the raw materials; the total weight of the raw materials is the total weight of the dichloroethylene and the trifluoromethane.

5. The process for the co-production of HFO-1234yf and HFO-1234ze according to claim 1, characterized in that, The reaction temperature of step (1) is 150-300°C, the reaction pressure is 1-3 MPa, and the reaction time is 2-6 h.

6. The process for the co-production of HFO-1234yf and HFO-1234ze according to claim 1, characterized in that, The second catalyst is fluorinated chromium oxide or fluorinated aluminum oxide.

7. The process for the co-production of HFO-1234yf and HFO-1234ze according to claim 1, characterized in that, The step (2) has a reaction temperature of 250-400℃, a pressure of 0.1-0.5 MPa, and a space velocity of 500-1500 h -1 .

8. The process for the co-production of HFO-1234yf and HFO-1234ze according to claim 1, characterized in that, The molar ratio of the anhydrous hydrogen fluoride to the trifluoromonochloropropene is (2-5):

1.

9. The process for the co-production of HFO-1234yf and HFO-1234ze according to claim 1, characterized in that, The third catalyst is a Fe-Mo-Mg-F catalyst, and the molar ratio of Fe, Mo and Mg is (3-4):(0.5-1):(5-7).

10. The process for the co-production of HFO-1234yf and HFO-1234ze according to claim 1, characterized in that, The step (3) reaction temperature is: 280~450℃, pressure is: 0.5~2MPa, airspeed is 800~2000h -1 ; The method of steps (1), (2) or (3) further comprises recycling the unreacted reaction substances, recovering or incinerating the by-products after the reaction products are separated and refined.