Method for co-producing 3,3,3-trifluoropropene and 2,3,3,3-tetrafluoropropene

Abstract

The present invention discloses a method for co-producing 3,3,3-trifluoropropene and 2,3,3,3-tetrafluoropropene. 1,1,1,3-tetrachloropropane, 1,1,1,2,3-pentachloropropane, and hydrogen fluoride are introduced into a first reactor and reacted over a first catalyst to obtain a reaction product from the first reactor. The reaction product from the first reactor is then rectified to obtain a 3,3,3-trifluoropropene product and a bottom product. The bottom product is mixed with hydrogen fluoride and introduced into a second reactor, where it is reacted over a second catalyst to obtain a reaction product from the second reactor. Hydrogen chloride is separated from the reaction product from the second reactor, which is then washed with water, washed with alkali, and dried to obtain the 2,3,3,3-tetrafluoropropene product. The present invention has the advantages of a simple process, high efficiency, high operational flexibility, low investment, and low energy consumption.

Description

[Technical Field]

[0001] The present invention relates to a method for producing fluorine-containing olefins, and more particularly to a method for co-producing 3,3,3-trifluoropropene and 2,3,3,3-tetrafluoropropene. [Background technology]

[0002] On September 15, 2021, China officially announced its support for the Kigali Amendment. The Kigali Amendment aims to globally regulate HFCs (third-generation refrigerants, mainly hydrofluorocarbons) and requires A5 countries, including China, to ban the production and consumption of HFCs in 2024. HFC reductions are scheduled to begin in 2029 and reach an 80% reduction by 2045. Therefore, there is an urgent need to develop and research green, efficient, and low-GWP refrigeration technologies.

[0003] Fourth-generation new refrigerants, primarily fluoroolefins (HFOs), have the advantages of zero ODP and extremely low GWP. A typical example is 2,3,3,3-tetrafluoropropene (HFO-1234yf, also known as R1234yf). HFO-1234yf has a boiling point of -29°C, zero ODP, a GWP of 4, and an atmospheric lifetime of 11 days, making it suitable for use as a replacement for HFC-134a in automotive air conditioning systems. There are three major industrially promising HFO-1234yf production methods: the 3,3,3-trifluoropropene method, the hexafluoropropene method, and the 1,1,2,3-tetrachloropropene (TCP) method. The 3,3,3-trifluoropropene method requires a long route, produces large amounts of wastewater, waste gas, and solid waste, and results in high product costs. The 1,1,2,3-tetrachloropropene method has fewer reaction steps and higher raw material utilization. The hexafluoropropene route is long and has a low overall yield. Other manufacturing processes are derived from intermediate raw materials from these three routes.

[0004] 3,3,3-Trifluoropropene (HFO-1243zf, also known as R1243zf) has a boiling point of -22°C, an ODP value of 0, a GWP value of 1, and an atmospheric lifetime of 7 days. R1243zf is primarily synthesized as a low-GWP refrigerant and a pharmaceutical intermediate. Depending on the primary starting material, its synthesis can be divided into 1,1,1,3-tetrachloropropane fluorination, trichloropropene (1,1,1-trichloropropene, 1,1,3-trichloro-1-propene) fluorination, trifluorochloromethane and ethylene addition, and carbene reaction. The 1,1,1,3-tetrachloropropane fluorination method is currently the most common method used in industrial production.

[0005] The investment in industrial equipment for producing HFO-1234yf and HFO-1243zf is high, and the operating costs are also high. However, the investment in general equipment for simultaneous production of HFO-1234yf and HFO-1243zf is low, so the production volume of the two products can be flexibly adjusted and the equipment operation is flexible. Therefore, the technology for simultaneous production of HFO-1234yf and HFO-1243zf has become a hot research topic.

[0006] For example, CN115322071A discloses a method for co-producing trifluoropropene and tetrafluoropropene using 1,1,1,2,3-pentafluoropropane as a raw material. This method uses 1,1,1,2,3-pentafluoropropane as a raw material and a metal ion-modified Mg-Al composite metal oxide as a catalyst, and the reaction is carried out in a fixed reactor. H2 is introduced during the reaction process, and the supply space velocity is set to 400-450 h2. -1The reaction temperature is 330-350°C, and the reaction pressure is atmospheric pressure. This invention provides a new method for producing fluorinated olefins, which simultaneously produces 3,3,3-trifluoropropene, 1,3,3,3-tetrafluoropropene, and 2,3,3,3-tetrafluoropropene in a one-step reaction. The drawbacks are that the main product is tetrafluoropropene, while trifluoropropene has low selectivity, which limits production flexibility. In addition, the addition of hydrogen makes subsequent separation difficult and increases costs. Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention addresses the shortcomings of the prior art by providing a method for co-producing HFO-1243zf and HFO-1234yf with a simple process, high yield, good selectivity, and low energy consumption. [Means for solving the problem]

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is: Step (a) of introducing 1,1,1,3-tetrachloropropane (HCC-250fb), 1,1,1,2,3-pentachloropropane (HCC-240db), and hydrogen fluoride (HF) into a first reactor and reacting them under the action of a first catalyst to obtain a reaction product of the first reactor; Step (b) of introducing the reaction product of the first reactor into a first fractionator and separating it to obtain a first fractionator top component and a first fractionator bottom component; Step (c) of introducing the top fraction of the first fractionator into a second fractionator and separating it to obtain a 3,3,3-trifluoropropene product and hydrogen chloride (HCl), and introducing the bottom fraction of the first fractionator and hydrogen fluoride into a second reactor and reacting them with each other over a second catalyst to obtain a reaction product in the second reactor; Step (d) of introducing the reaction product of the second reactor into a third fractionator and separating it to obtain a third fractionator top component and a third fractionator bottom component; Step (e) of introducing the top fraction of the third fractionator into a fourth fractionator and separating it to obtain hydrogen chloride and a bottom fraction of the fourth fractionator; and step (f) of washing the bottom fraction of the fourth fractionator with water, washing with an alkali, and drying to obtain a 2,3,3,3-tetrafluoropropene product.

[0009] In a preferred embodiment of the present invention, the first catalyst is a supported metal catalyst, and the supported metal catalyst is at least one of CrCl3, SbCl3, SnCl4, TiCl4, and SbCl5 supported on a carrier, and the carrier is one of activated carbon, silica, alumina, and molecular sieve.

[0010] In a preferred embodiment of the present invention, the first catalyst is one of CrCl3 / C, SbCl3 / SiO2, SnCl4 / Al2O3, TiCl4 / molecular sieve, and SbCl5 / C.

[0011] In a preferred embodiment of the present invention, the second catalyst is a supported antimony-based catalyst or a supported chromium-based catalyst, and the content of antimony or chromium is 5 to 25% by mass.

[0012] In a preferred embodiment of the present invention, the second catalyst is one of SbCl5 / SiO2, Cr2O3 / Al2O3, CrCl3 / C, and SbCl5 / molecular sieve.

[0013] In a preferred embodiment of the present invention, in step (a), the molar ratio of the 1,1,1,3-tetrachloropropane to 1,1,1,2,3-pentachloropropane is 0.5 to 2:1, the molar ratio of the hydrogen fluoride to 1,1,1,2,3-pentachloropropane is 7.5 to 60:1, and the reaction is carried out at a temperature of 50 to 280°C and a pressure of 0.1 to 1.5 MPa.

[0014] In a preferred embodiment of the present invention, the amount of hydrogen fluoride used in step (c) is 3 to 10 times the number of moles of 1,1,1,2,3-pentachloropropane used in step (a), and the reaction is carried out at a temperature of 100 to 350°C and a pressure of 0.1 to 1.5 MPa.

[0015] In a preferred embodiment of the present invention, the first reactor and the second reactor are liquid-phase reactors or gas-phase fixed-bed reactors.

[0016] In a preferred embodiment of the present invention, the bottom fraction of the third fractionator obtained in step (d) is recycled to the first reactor to continue the reaction.

[0017] In the present invention, HFO-1243zf and HFO-1234yf are co-produced using two reactors. In the first reactor, the fluorination reaction of 1,1,1,3-tetrachloropropane and 1,1,1,2,3-pentachloropropane mainly occurs, and the main equation is as follows: CCl3CH2CH2Cl(HCC-250fb)+3HF→CF3CH=CH2(HFO-1243zf)+4HCl CCl3CHClCH2Cl(HCC-240db)+3HF→CF3CCl=CH2(HCFO-1233xf)+4HCl CCl3CHClCH2Cl(HCC-240db)+2HF→CF2ClCCl=CH2(HCFO-1232xf)+3HCl CF3CH=CH2(HFO-1243zf)+HF→CF3CHFCH3(HFC-254eb) CF3CCl=CH2(HCFC-1233xf)+HF→CF3CFClCH3(HCFC-244bb)

[0018] The boiling points of some of the materials of the present invention are as follows: [Table 0]

[0019] In the present invention, the first reactor may be a liquid-phase reactor or a gas-phase reactor. 1,1,1,3-tetrachloropropane, 1,1,1,2,3-pentachloropropane, and hydrogen fluoride are introduced into the first reactor to obtain a mixture containing CFCH=CH (HFO-1243zf), CFCCl=CH (HCFO-1233xf), CFClCCl=CH (HCFO-1232xf), CFCHFCH (HFC-254eb), and CFCFClCH (HFC-244bb). The mixture is then fractionated according to the boiling points of each substance. The material from the first reactor is introduced into a first fractionator for separation, and HFO-1243zf and HCl are separated at the top of the column. Next, HFO-1243zf and HCl are separated in a second fractionator to obtain the target product, HFO-1243zf. The bottom material of the first fractionator is fed directly to the second reaction step.

[0020] In the second reactor of the present invention, the fluorination reaction of CF3CCl=CH2 mainly occurs, and the main equation is as follows: CF3CCl=CH2(HCFO-1233xf)+HF→CF3CF=CH2(HFO-1234yf)+HCl CF3CF=CH2(HFO-1234yf)+HF→CF3CF2CH3(HFC-245cb)+HCl

[0021] The material from the bottom of the first fractionator and HF are introduced into a second reactor, yielding a mixture containing CFCF=CH (HFO-1234yf), CFCFCH (HFC-245cb), and HCl. After fractionation according to the boiling points of each substance, the material from the second reactor is introduced into a third fractionator, where HFO-1234yf and HCl are separated at the top of the third fractionator. The bottom material is recycled to the first reactor for reaction. After HFO-1234yf and HCl are separated in a fourth fractionator, HCl is separated at the top, and crude HFO-1234yf is obtained at the bottom. This is then washed with water, washed with alkali, and dried as is customary in the art to yield the 2,3,3,3-tetrafluoropropene product.

[0022] The main raw materials in the present invention are 1,1,1,3-tetrachloropropane and 1,1,1,2,3-pentachloropropane. 1,1,1,3-tetrachloropropane and 1,1,1,2,3-pentachloropropane may be charged individually into the first reactor, or may be mixed and then charged into the first reactor. The mixture of 1,1,1,3-tetrachloropropane and 1,1,1,2,3-pentachloropropane may be produced by physically mixing 1,1,1,3-tetrachloropropane and 1,1,1,2,3-pentachloropropane, or by chlorinating the liquid phase of 1,1,1,3-tetrachloropropane. For example, a mixture of 1,1,1,3-tetrachloropropane and 1,1,1,2,3-pentachloropropane with different molar ratios may be obtained by controlling the conversion rate of 1,1,1,3-tetrachloropropane. [Effects of the Invention]

[0023] Compared with the prior art, the present invention has the following advantages: 1.High yield and excellent selectivity The overall conversion of the raw materials 1,1,1,3-tetrachloropropane and 1,1,1,2,3-pentachloropropane is above 96.8%, and the overall selectivity of the products 3,3,3-trifluoropropene and 2,3,3,3-tetrafluoropropene is above 98.2%. 2. The process is simple and low cost. The present invention improves reaction efficiency by optimizing parameters such as the reaction process, the catalyst and material ratio, reaction temperature, and reaction pressure. The reaction temperature and reaction pressure are relatively low, and the reaction conditions are mild and easy to control, greatly simplifying the production process and reducing energy consumption. The raw materials, 1,1,1,3-tetrachloropropane and 1,1,1,2,3-pentachloropropane, are inexpensive and easily available, further reducing production costs. 3. Green and environmentally friendly, with less waste air, waste water and solid waste. The unreacted raw materials and intermediate products of the present invention can be recycled to the reactor for continued reaction, significantly reducing the discharge of waste air, waste water and solid waste. 4. Low investment and flexible operation. One device can simultaneously produce two products, HFO-1243zf and HFO-1234yf, and the product ratio can be flexibly adjusted according to market needs, significantly reducing equipment investment. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a flow chart of the process of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] The process of the present invention is shown in Figure 1. A mixture of HCC-250fb and HCC-240db feedstock and HF are introduced into a first reactor 1 packed with a first catalyst and reacted. The resulting reaction product is introduced into a first fractionator 2, producing a first fractionator top component and a bottom liquid of the first fractionator containing unreacted feedstock and other heavy components. The top liquid of the first fractionator is introduced into a second fractionator 3, producing a 3,3,3-trifluoropropene product in the bottom liquid and hydrogen chloride at the top. The bottom liquid of the first fractionator and hydrogen fluoride are introduced into a mixer 4 and mixed before being introduced into a second reactor 5 packed with a second catalyst. The mixture is reacted by the action of the second catalyst to produce a reaction product of the second reactor. The reaction product of the second reactor is introduced into a third fractionator 6 and separated to produce a third fractionator top component and a third fractionator bottom component. The top fraction of the third fractionator is introduced into the fourth fractionator 7 for separation, with hydrogen chloride being obtained at the top and crude 2,3,3,3-tetrafluoropropene being obtained in the bottom of the fractionator. The crude 2,3,3,3-tetrafluoropropene is then washed with water, alkali, and dried to obtain the 2,3,3,3-tetrafluoropropene product. The HCl separated at the top of the second fractionator 3 and the top of the fourth fractionator 7 is sent to another device for use. The bottom fraction of the third fractionator is returned to the first reactor 1 for recycling.

[0026] The technical solutions of the present invention will be described more clearly and completely below with reference to the embodiments. It is clear that the described embodiments are only a part of the embodiments of the present invention, and are not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without any creative work fall within the scope of protection of the present invention.

[0027] Example 1 The raw material mixture of HCC-250fb and HCC-240db and HF were introduced into the first reactor (liquid-phase reactor) filled with the first catalyst CrCl3 / C. The temperature and pressure were set to react under the action of the first catalyst. The reaction product was introduced into the first fractionator and separated. The product from the bottom of the first fractionator was mixed with HF and then introduced into the second reactor (liquid-phase reactor) filled with the second catalyst SbCl5 / SiO2 (Sb loading: 5 wt%) to react. The temperature and pressure were set to react under the action of the second catalyst. The reaction product was introduced into the third fractionator and separated. The reaction parameters for the first and second reactors are shown in Table 1, and the composition of organic matter at the outlet was shown in Table 2.

[0028] Example 2 The raw material mixture of HCC-250fb and HCC-240db and HF were introduced into the first reactor (gas-phase fixed-bed reactor) packed with the first catalyst SbCl3 / SiO2. The temperature and pressure were set to allow the first catalyst to react with each other. The reaction product was introduced into the first fractionator and separated. The bottom product of the first fractionator was mixed with HF and then introduced into the second reactor (liquid-phase reactor) packed with the second catalyst Cr2O3 / Al2O3 (Cr loading: 10 wt%) to allow the second catalyst to react with each other. The temperature and pressure were set to allow the second catalyst to react with each other. The reaction product was introduced into the third fractionator and separated. The reaction parameters of the first and second reactors are shown in Table 1, and the composition of organic matter at the outlet was shown in Table 2.

[0029] Example 3 The raw material mixture of HCC-250fb and HCC-240db and HF were introduced into the first reactor (liquid-phase reactor) packed with the first catalyst SnCl4 / Al2O3. The temperature and pressure were set to react under the action of the first catalyst. The reaction product was introduced into the first fractionator and separated. The product from the bottom of the first fractionator was mixed with HF and then introduced into the second reactor (gas-phase fixed-bed reactor) packed with the second catalyst CrCl3 / activated carbon (Cr loading: 15 wt%) to react. The temperature and pressure were set to react under the action of the second catalyst. The reaction product was introduced into the third fractionator and separated. The reaction parameters for the first and second reactors are shown in Table 1, and the composition of organic matter at the outlet was shown in Table 2.

[0030] Example 4 The raw material mixture of HCC-250fb and HCC-240db and HF were introduced into the first reactor (gas-phase fixed-bed reactor) filled with the first catalyst TiCl4. The temperature and pressure were set to react under the action of the first catalyst, and the reaction product was introduced into the first fractionator and separated. The bottom product of the first fractionator was mixed with HF, and then introduced into the second reactor (gas-phase fixed-bed reactor) filled with the second catalyst SbCl5 / molecular sieve (Sb loading: 20 wt%) to react there. The temperature and pressure were set to react under the action of the second catalyst, and the reaction product was introduced into the third fractionator and separated there. The reaction parameters of the first and second reactors are shown in Table 1, and the composition of organic matter at the outlet is shown in Table 2.

[0031] Example 5 The raw material mixture of HCC-250fb and HCC-240db and HF were introduced into the first reactor (gas-phase fixed-bed reactor) packed with the first catalyst SbCl5. The temperature and pressure were set to allow the first catalyst to react with each other. The reaction product was introduced into the first fractionator and separated. The bottom product of the first fractionator was mixed with HF and then introduced into the second reactor (gas-phase fixed-bed reactor) packed with the second catalyst Cr2O3 / alumina (Cr loading: 25 wt%) to allow the second catalyst to react with each other. The temperature and pressure were set to allow the second catalyst to react with each other. The reaction product was introduced into the third fractionator and separated. The reaction parameters for the first and second reactors are shown in Table 1, and the composition of organic matter at the outlet was shown in Table 2.

[0032] [Table 1]

[0033] [Table 2] [Explanation of symbols]

[0034] 1. First reactor 2. First rectification tower 3. Second rectification tower 4 mixer 5. Second Reactor 6. Third rectification tower 7 Fourth rectification tower

Claims

1. A method for co-producing 3,3,3-trifluoropropene and 2,3,3,3-tetrafluoropropene, comprising: Step (a) of introducing 1,1,1,3-tetrachloropropane, 1,1,1,2,3-pentachloropropane, and hydrogen fluoride into a first reactor and reacting them under the action of a first catalyst to obtain a reaction product in the first reactor; Step (b) of introducing the reaction product of the first reactor into a first fractionator and separating it to obtain a first fractionator top component and a first fractionator bottom component; Step (c) of introducing the top fraction of the first fractionator into a second fractionator and separating them to obtain a 3,3,3-trifluoropropene product and hydrogen chloride, and introducing the bottom fraction of the first fractionator and hydrogen fluoride into a second reactor and reacting them with each other over a second catalyst to obtain a reaction product in the second reactor; Step (d) of introducing the reaction product of the second reactor into a third fractionator and separating it to obtain a third fractionator top component and a third fractionator bottom component; Step (e) of introducing the top fraction of the third fractionator into a fourth fractionator and separating it to obtain hydrogen chloride and a bottom fraction of the fourth fractionator; and step (f) washing the bottom fraction of the fourth rectification column with water, washing with an alkali, and drying to obtain a 2,3,3,3-tetrafluoropropene product.

2. The first catalyst is a supported metal catalyst, and the supported metal catalyst is CrCl ３ , SbCl ３ , SnCl ４ , TiCl ４ , SbCl ５ 2. The method for co-producing 3,3,3-trifluoropropene and 2,3,3,3-tetrafluoropropene according to claim 1, wherein at least one of the above is supported on a carrier, and the carrier is one of activated carbon, silica, alumina, and molecular sieve.

3. The first catalyst is CrCl ３ / C, SbCl ３ / SiO ２ , SnCl ４ / Al ２ O ３ , TiCl ４ / Molecular sieve, SbCl ５ 3. The method for co-producing 3,3,3-trifluoropropene and 2,3,3,3-tetrafluoropropene according to claim 2, wherein the fluorocarbon is one of the following:

4. 2. The method for co-producing 3,3,3-trifluoropropene and 2,3,3,3-tetrafluoropropene according to claim 1, wherein the second catalyst is a supported antimony-based catalyst or a supported chromium-based catalyst, and the content of antimony or chromium is 5 to 25% by mass.

5. The second catalyst is SbCl ５ / SiO ２ , Cr ２ O ３ / Al ２ O ３ , CrCl ３ / C, SbCl ５ 5. The method for co-producing 3,3,3-trifluoropropene and 2,3,3,3-tetrafluoropropene according to claim 4, wherein the catalyst is one of the following: a molecular sieve;

6. 2. The method for co-producing 3,3,3-trifluoropropene and 2,3,3,3-tetrafluoropropene according to claim 1, wherein in step (a), the molar ratio of 1,1,1,3-tetrachloropropane to 1,1,1,2,3-pentachloropropane is 0.5 to 2:1, the molar ratio of hydrogen fluoride to 1,1,1,2,3-pentachloropropane is 7.5 to 60:1, and the reaction is carried out at a temperature of 50 to 280° C. and a pressure of 0.1 to 1.5 MPa.

7. 2. The method for co-producing 3,3,3-trifluoropropene and 2,3,3,3-tetrafluoropropene according to claim 1, wherein the amount of hydrogen fluoride in step (c) is 3 to 10 times the number of moles of 1,1,1,2,3-pentachloropropane in step (a), and the reaction is carried out at a temperature of 100 to 350°C and a pressure of 0.1 to 1.5 MPa.

8. 2. The method for co-producing 3,3,3-trifluoropropene and 2,3,3,3-tetrafluoropropene according to claim 1, wherein the first reactor and the second reactor are liquid-phase reactors or gas-phase fixed-bed reactors.

9. The method for co-producing 3,3,3-trifluoropropene and 2,3,3,3-tetrafluoropropene according to claim 1, characterized in that the bottom fraction of the third fractionator obtained in step (d) is recycled to the first reactor to continue the reaction.

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