Preparation method of 1, 1, 1, 4, 4, 4-hexafluoro-2-butene

Abstract

The invention discloses a preparation method of 1, 1, 1, 4, 4, 4-hexafluoro-2-butene, and belongs to the technical field of organic fluorine chemical industry. The composition is characterized in that a trifluoromethane raw material flow and a trifluoropropyne raw material flow are respectively introduced into a reactor in parts by weight, in the presence of a catalyst, a gas phase reaction is performed to generate a reaction product flow, the active component of the catalyst is composed of one or more of a group VIII metal and a group IB metal element, the carrier is multistage micro / mesoporous Cr2O3, and the active component of the catalyst is one or more of a group IB metal element and a group IB metal element. Adding reaction promoting gas in the reaction stage; the reaction product flow is fed into a separation system, the target product 1, 1, 1, 4, 4, 4-hexafluoro-2-butene is obtained through separation, and excessive trifluoromethane is separated and circularly fed into the initial reactor to serve as a reaction raw material. According to the arrangement of reaction raw materials, excessive trifluoromethane is selected to promote full conversion of trifluoropropyne, meanwhile, in a subsequent separation system, trifluoromethane is recycled and serves as the reaction raw materials to circularly enter an initial reactor, full utilization of the raw materials is promoted, and the production cost is effectively reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of organic fluorine chemical industry, and specifically relates to a preparation method for producing 1,1,1,4,4,4-hexafluoro-2-butene by reacting 3,3,3-trifluoropropyne and trifluoromethane as raw materials in the presence of a catalyst. Background Art

[0002] 1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336, R1336) is a hydrofluoroolefin (HFO)-like substance with zero ozone depletion potential (ODP) and extremely low greenhouse effect potential (GWP = 9.7), which has little impact on the environment. Because its performance is similar to that of CFC-11, HCFC-141b and HFC-245fa and other foaming agents, especially HCFC-141b, it is considered to be a new generation of green and environmentally friendly foaming agent and the ultimate green and environmentally friendly substitute for HCFC-141b and other foaming agent products. At present, HFO-1336 is mainly used in refrigerators, board polyurethane insulation material foaming agent, refrigerant and aerosol, etc. With the continuous deepening of its product application research, the application field is also expanding, and it can be expected that HFO-1336 has a broad market prospect.

[0003] Trifluoromethane (CHF3), also known as fluoroform, is a byproduct of the industrial preparation of difluorochloromethane (HCFC-22). Its content in the generated HCFC-22 is about 1.5~3wt%. The annual output in my country is as high as about 13,000~15,000 tons.

[0004] CHCl3+2HF→CHClF2+2HCl During the reaction, CHClF2 continues to fluorinate, producing a byproduct, CHF3. At present, trifluoromethane has been controlled for emission internationally and is used as a carbon trading object. The traditional treatment methods for trifluoromethane are mainly thermal incineration, plasma treatment and strong alkali decomposition. These methods not only fail to achieve economic benefits, but also consume a lot of energy, and have the disadvantages of high cost, high energy consumption and environmental pollution. Therefore, it is particularly important and critical to explore a method of using trifluoromethane as a raw material that is both environmentally friendly and sustainable.

[0005] There are two main methods for the synthesis of 3,3,3-trifluoropropyne:

[0006] (1) Liquid phase dehydrohalogenation

[0007] EP2143702 reported that in an ethanol solvent, 130.5 g of Z-1-chloro-3,3,3-trifluoropropene was reacted with 61.7 g of potassium hydroxide at 38° C. for 2.5 hours, and the conversion rate of Z-1-chloro-3,3,3-trifluoropropene was 99.2%, and the selectivity of 3,3,3-trifluoropropyne was 98.4%.

[0008] JP6032085 reported that in a potassium hydroxide aqueous solution, Z-1-chloro-3,3,3-trifluoropropene was reacted at 50°C for 2 hours with a reaction pressure not exceeding 0.2 MPa, and the yield of 3,3,3-trifluoropropyne was 85.9% and the purity was 97.5%.

[0009] WO2016 / 132111 reported that in an autoclave, Z-1-chloro-3,3,3-trifluoropropene was reacted with a 40% mass percent concentration of KOH aqueous solution at 38°C for 5 hours, and the conversion of Z-1-chloro-3,3,3-trifluoropropene was 95.33%, and the selectivity of 3,3,3-trifluoropropyne was 99.8%. It was also reported that Z-1233zd (20.4 g) dissolved in methanol (19.2 g) was charged into a 100 mL autoclave equipped with a condenser connected to a sample bottle cooled by drying, the autoclave was stirred and heated to 38°C, and then a 40% KOH solution (43.8 g) was added by a syringe pump within 2 hours, the mixture was heated for another 3 hours, and the gaseous product was collected. The reaction results are as follows: the conversion rate of Z-1-chloro-3,3,3-trifluoropropene is 94.20%, and the selectivity of 3,3,3-trifluoropropyne is 99.7%.

[0010] US2014 / 343330 reported that potassium hydroxide (powder, 31.6 g) and phase transfer catalyst Aliquat 336 (chemical formula: C 25 H 54 ClN, 1.0 g) was dissolved in 42.0 g of tert-butyl alcohol, heated to reflux, and then E-1-chloro-3,3,3-trifluoropropene (19.0 g) dissolved in 17 mL of ether was added dropwise. After the addition, the mixture was stirred under reflux for another 1 to 2 hours to drive out the product. The product (9.2 g of clear liquid) was collected in a dry ice-acetone cold trap at -70 ° C through a water-cooled reflux condenser. The yield of 3,3,3-trifluoropropyne was 28.9% and the purity was 40.25%.

[0011] JP2018 / 90512 reported that in a 500ml SUS-316 reactor connected to a pressure gauge and a discharge valve, 16.80g (0.3 mol) of potassium hydroxide ground powder and 26.10g (0.2mol) of Z-1,3,3,3-tetrafluoropropene were introduced into the reactor and sealed, and the mixture was heated at 70°C for 9 hours while stirring with a magnetic stirrer. The final pressure of the reaction was 0.5MPa. After the reaction was completed, the take-out valve was opened, and the organic matter was liquefied into a cold trap (cooled with methanol + dry ice) and collected. The reaction results were: the conversion rate of Z-1,3,3,3-tetrafluoropropene was 64.5%, and the selectivity of 3,3,3-trifluoropropyne was 98.4%.

[0012] (2) Gas phase dehydrohalogenation

[0013] WO2010 / 95764 reported that in the presence of KF / C catalyst (30 g), 20 mL / min of E-1-chloro-3,3,3-trifluoropropene was introduced for reaction at a temperature of 400°C, a contact time (ratio of catalyst mass to feedstock flow rate) of 60.0 g-sec / mL, and a pressure of 0.1 MPa. After continuous operation for 2 h, the reaction results were: the conversion rate of E-1-chloro-3,3,3-trifluoropropene was 16.7%, and the selectivity of 3,3,3-trifluoropropyne was 83.2%

[0014] CN113004117B reports a method for synthesizing 3,3,3-trifluoropropyne with high conversion rate and high selectivity by using E-1-halogen-3,3,3-trifluoropropene or / and Z-1-halogen-3,3,3-trifluoropropene or / and 2-halogen-3,3,3-trifluoropropene (halogen = F or Cl or Br or I) as raw materials through gas phase dehydrohalogenation reaction, namely: in the presence of a catalyst, in a tubular reactor, E-1-halogen-3,3,3-trifluoropropene or / and Z-1-halogen-3,3,3-trifluoropropene or / and 2-halogen-3,3,3-trifluoropropene (halogen = F or Cl or Br or I) undergo gas phase dehydrohalogenation reaction to obtain 3,3,3-trifluoropropyne.

[0015] In summary, the preparation method of trifluoropropyne is mainly obtained by dehydrohalogenation reaction of E-1-halo-3,3,3-trifluoropropene or / and Z-1-halo-3,3,3-trifluoropropene or / and 2-halo-3,3,3-trifluoropropene (halogen = F or Cl or Br or I), mainly E-1-chloro-3,3,3-trifluoropropene or / and Z-1-chloro-3,3,3-trifluoropropene or / and 2-chloro-3,3,3-trifluoropropene. Z-1-chloro-3,3,3-trifluoropropene exists as an isomer in the production process of E-1-halo-3,3,3-trifluoropropene. 2-Chloro-3,3,3-trifluoropropene is an intermediate product in the production process of 2,3,3,3-tetrafluoropropene. E-1-chloro-3,3,3-trifluoropropene, Z-1-chloro-3,3,3-trifluoropropene and 2-chloro-3,3,3-trifluoropropene have all been industrially produced and are easily available.

[0016] At present, there are many methods for preparing 1,1,1,4,4,4-hexafluoro-2-butene, mainly including hexafluoro-2-butyne, copolymerization of trichloromethane and hexafluoropropylene, CFC-113 coupling, fluorination and dechlorination route, synthesis by polymerization of carbon tetrachloride and ethylene and fluorination and dechlorination route, HFC-347mef dehydrofluorination, HCFC-123 coupling and synthesis by polymerization of carbon tetrachloride and trifluoropropylene and other industrial routes.

[0017] Using hexafluoro-2-butyne hydrogenation as raw material, Pd or Lindlar catalyst catalytic hydrogenation can selectively generate (Z)-1,1,1,4,4,4-hexafluoro-2-butene. Aromatic amine, quinoline or pyridine and other toxic solvents are usually added to the reaction system to modify the catalyst. CN102892738A found that the use of 5% Pd catalyst loaded on calcium carbonate poisoned by 3.5% lead has a good catalytic hydrogenation effect. This route is simple and suitable for industrial production. However, its main problem is that the reaction raw material hexafluoro-2-butyne is difficult to prepare and the cost is high.

[0018] Chinese patent CN102892738A reports that through thermal addition reaction, the CH bond of CHCl3 is inserted into hexafluoropropylene to form CCl3CF2CHFCF3, which is then subjected to HF fluorination, hydrogenation and HF removal steps to finally obtain hexafluoro-2-butyne, and then hexafluoro-2-butyne is selectively hydrogenated to form 1,1,1,4,4,4-hexafluoro-2-butene. This route has complicated steps and low yield.

[0019] Chinese patent CN102884030A utilizes a similar reaction method, where CCl4 reacts with 3,3,3-trifluoropropylene, and the target product can be prepared through three steps.

[0020] Patent US2011 / 01288350 found that CFC-113a (CCl3CF3) was mixed with 1,2-dichloroethylene, placed in a high-pressure reactor under the action of an iron catalyst and 3-butyl phosphate, and reacted for a certain period of time to obtain the intermediate product CF3CCl2CHClCHCl2. It was then chlorinated to obtain CF3CCl2CCl2CCl3, fluorinated with HF to obtain CF3CCl2CCl2CCF3, and hydrogenated with a Cu / AC catalyst at 300~350℃ to form 1,1,1,4,4,4-hexafluoro-2-butene.

[0021] Using the most basic raw materials CCl4 and CH2=CH2 through polymerization reaction, Chinese patent CN102892736A found that the product is CCl3CH2CH2Cl (HCC-250), and the de-HCl product CCl3CH=CH2 is then polymerized with CCl4 to obtain CCl3CHClCH2CCl3. After HF fluorination, the product is 1,1,1,4,4,4-hexafluoro-2-butene.

[0022] Chinese patent CN102015592A uses HCFC-123 (CF3CHCl2) as raw material, mixes with metallic copper and methylamine or ethylamine, etc. and puts into a reactor, reacts at 60°C for about 10 hours, and the target product 1,1,1,4,4,4-hexafluoro-2-butene can be collected in the product. The reaction is an intermittent reaction, which takes a long time, has a long industrial production cycle, and the cost of the metallic copper consumed is also high.

[0023] In order to overcome the shortcomings of the prior art, the present invention aims to provide a method for preparing 1,1,1,4,4,4-hexafluoro-2-butene which has a simple process, few steps and is easy to industrialize. Summary of the invention

[0024] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a method for preparing 1,1,1,4,4,4-hexafluoro-2-butene.

[0025] The technical solution adopted by the present invention to solve the technical problem is: a method for preparing 1,1,1,4,4,4-hexafluoro-2-butene, characterized in that the catalyst is prepared by an impregnation method and the catalyst is pretreated by fluorination before use.

[0026] Specifically, trifluoromethane raw material flow and trifluoropropyne raw material flow are respectively introduced into the reactor, and in the presence of a catalyst, a gas phase reaction is carried out to generate a reaction product flow, the carrier is multi-stage micro / mesoporous Cr2O3, and a reaction promoting gas is added during the reaction stage; the reaction product flow is sent to a separation system to separate and obtain the target product 1,1,1,4,4,4-hexafluoro-2-butene, and excess trifluoromethane is separated and recycled into the initial reactor as a reaction raw material.

[0027] The active component of the catalyst is composed of one or more of Group VIII metals and Group IB metal elements.

[0028] Specifically, the active component of the catalyst is one or more of Fe, Co, Ni, Pd, Pt, Cu, Ag, Au, and K.

[0029] The above metal elements have good catalytic activity, can promote the reaction of trifluoromethane and trifluoropropyne, and improve the reaction rate and conversion rate. Transition metals such as Fe and Ni can provide active sites, which are helpful for the adsorption and activation of reactants, thereby accelerating the reaction.

[0030] Specifically, the raw materials of the catalyst active components are preferably chlorides, carbonates, nitrates, acetates and sulfates corresponding to the active component metals.

[0031] Salts are easily dissolved and dispersed on the carrier during the impregnation process, which can achieve uniform loading of active components and improve the activity and stability of the catalyst. For example, chlorides and nitrates can be decomposed into corresponding metal oxides during heat treatment to form active sites, while carbonates and acetates can provide buffering effects and adjust the surface properties of the catalyst.

[0032] Specifically, the reaction temperature is 200°C to 400°C.

[0033] Specifically, the reaction residence time is 1s to 10s.

[0034] Specifically, the molar ratio of trifluoromethane to trifluoropropyne is 1-3:1.

[0035] Excess trifluoromethane can provide sufficient reactants to drive the reaction toward the direction of generating the target product. At the same time, in the subsequent separation system, trifluoromethane is recovered and recycled, reducing the cost of raw materials.

[0036] Specifically, the reaction promoting gas is CO2.

[0037] CO2 can reduce carbon deposits on the catalyst surface, keep the active sites of the catalyst clean, and improve the stability and anti-carbon deposition ability of the catalyst.

[0038] Specifically, the molar ratio of the reaction promoting gas to trifluoropropyne is 0.01-0.1:1.

[0039] Specifically, the reaction is continuously carried out in a fixed bed reactor, which can provide stable reaction conditions, facilitate the control of reaction parameters, ensure the stability of product quality, and meet the needs of industrial production.

[0040] Specifically, the catalyst is prepared by an impregnation method, and the catalyst needs to be pre-treated by fluorination before use.

[0041] The impregnation method can make the active components evenly distributed on the carrier, thereby improving the activity and selectivity of the catalyst; the fluorination pretreatment can improve the surface properties of the catalyst and enhance its catalytic performance; the catalyst pretreated by fluorination can better adsorb and activate the reactants, improve the conversion rate and selectivity of the reaction, and also help to improve the stability and life of the catalyst.

[0042] Compared with the prior art, the carbon dioxide-based multi-arm polycarbonate composition of the present invention has the following beneficial effects:

[0043] 1. Provide a new route for preparing 1,1,1,4,4,4-hexafluoro-2-butene.

[0044] 2. Trifluoromethane raw material is one of the high-boiling components in the industrial production of the company's product difluorochloromethane. It is low-cost and easy to obtain.

[0045] 3. The method for preparing 1,1,1,4,4,4-hexafluoro-2-butene provided by the present invention has the advantages of low raw material cost, less three wastes, high conversion rate, high product purity, and easy to achieve reaction conditions.

[0046] 4. For the setting of reaction raw materials, trifluoromethane is selected in excess to promote the full conversion of trifluoropropyne. At the same time, in the subsequent separation system, trifluoromethane is recovered and used as a reaction raw material and circulated into the initial reactor, which promotes the full utilization of raw materials and effectively reduces production costs.

[0047] 5. By adding reaction-promoting gas during the reaction stage, carbon deposits are not easily generated on the catalyst surface, thereby effectively improving the catalyst's stability, anti-carbon deposition ability, and trichloroethylene conversion rate. DETAILED DESCRIPTION

[0048] The present invention is described in detail below by way of examples. Unless otherwise specified, all raw materials used are commercially available.

[0049] Catalyst preparation:

[0050] The catalyst is prepared by an impregnation method, and the specific preparation method is as follows: the active component metal salt is added to deionized water and stirred to dissolve to obtain a metal salt solution, i.e., an impregnation solution; the carrier is impregnated in the impregnation solution at room temperature for 10 to 24 hours, and then filtered and placed in a drying oven, and dried at 100 to 120° C. for 10 to 24 hours to obtain a catalyst precursor, and the obtained precursor is calcined in an inert gas atmosphere at 500° C. to 800° C. for 10 to 24 hours to obtain a catalyst. The inert gas is preferably nitrogen, argon or helium.

[0051] Catalyst activation:

[0052] The catalyst is pretreated by fluorination before use, preferably by HF treatment. The specific pretreatment method is to place the catalyst in a catalyst reactor, and introduce a HF-inert gas mixture with a molar ratio of 1 to 20:1, or a mixed gas with a molar ratio of 5 to 10:1. Inert gas: nitrogen, helium, argon mixed with HF. The fluorination pretreatment temperature is 180°C to 380°C, and the fluorination treatment time is 60h to 180h.

[0053] Example 1

[0054] Catalyst preparation: Dissolve 5g of ferric chloride and add it to 100g of multi-level micro / mesoporous Cr2O3 carrier. After immersion for 24 hours, filter and place in a drying oven. Dry at 120°C for 24 hours to obtain a catalyst precursor. The obtained precursor is calcined at 800°C in an inert gas atmosphere for 24 hours to prepare the catalyst used. Place the catalyst in a fixed bed reactor and continuously introduce a mixed gas of HF and N2 to treat the catalyst to obtain a composite fluoride 5Fe / Cr loaded with iron ions. x F y .

[0055] Take 60mL of catalyst 5Fe / Cr x Fy The mixture was transferred to a fixed-bed tubular reactor, first charged with carbon dioxide, heated to 200°C and dried for 2 hours, then trifluoromethane was introduced, and then trifluoropropyne was introduced. The molar ratio of trifluoropropyne to trifluoroiodomethane and carbon dioxide was 1:3:0.1. The residence time was 10 seconds. Excess trifluoromethane was purified and recycled into the initial reactor as a reaction raw material. The target product 1,1,1,4,4,4-hexafluoro-2-butene was found to have a purity of 99.5% and a yield of 85.7% by gas chromatography.

[0056] Embodiments 2 to 10

[0057] 1,1,1,4,4,4-hexafluoro-2-butene was synthesized by the same method as in Example 1, except that the catalyst loading element, reaction temperature, molar ratio of trifluoropropyne to trifluoromethane and carbon dioxide and residence time were changed.

[0058] Table 1 .

[0059] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing 1,1,1,4,4,4-hexafluoro-2-butene, characterized in that: A trifluoromethane raw material flow and a trifluoropropyne raw material flow are respectively introduced into the reactor, and in the presence of a catalyst, a gas phase reaction is performed to generate a reaction product flow, the carrier is a multi-stage micro / mesoporous Cr2O3, and a reaction promoting gas is added during the reaction stage; the reaction product flow is sent to a separation system to separate and obtain the target product 1,1,1,4,4,4-hexafluoro-2-butene, and excess trifluoromethane is separated and circulated into the initial reactor as a reaction raw material.

2. The method for preparing 1,1,1,4,4,4-hexafluoro-2-butene according to claim 1, characterized in that: The active component of the catalyst is one or more of Fe, Co, Ni, Pd, Pt, Cu, Ag, Au, and K.

3. A method for preparing 1,1,1,4,4,4-hexafluoro-2-butene according to claim 1, characterized in that: The raw materials of the catalyst active components are preferably chlorides, carbonates, nitrates, acetates and sulfates corresponding to the active component metals.

4. A method for preparing 1,1,1,4,4,4-hexafluoro-2-butene according to claim 1, characterized in that: The reaction temperature is 200°C to 400°C.

5. The method for preparing 1,1,1,4,4,4-hexafluoro-2-butene according to claim 1, characterized in that: The reaction residence time is 1s to 10s.

6. The method for preparing 1,1,1,4,4,4-hexafluoro-2-butene according to claim 1, characterized in that: The molar ratio of trifluoromethane to trifluoropropyne is 1-3:

1.

7. The method for preparing 1,1,1,4,4,4-hexafluoro-2-butene according to claim 1, characterized in that: The reaction promoting gas is CO2.

8. The method for preparing 1,1,1,4,4,4-hexafluoro-2-butene according to claim 1, characterized in that: The molar ratio of the reaction promoting gas to trifluoropropyne is 0.01-0.1:

1.

9. The method for preparing 1,1,1,4,4,4-hexafluoro-2-butene according to claim 1, characterized in that: The reaction is carried out continuously in a fixed bed reactor.

10. The method for preparing 1,1,1,4,4,4-hexafluoro-2-butene according to claim 1, characterized in that: The catalyst is prepared by an impregnation method and needs to be pre-treated by fluorination before use.