Method for cyclic application of co-production of 2,3,3,3-tetrafluoropropene and hydrogen chloride

Abstract

The present invention belongs to the technical field of preparation methods of refrigerants, and particularly relates to a method for co-producing 2,3,3,3-tetrafluoropropene and hydrogen chloride by cyclic reuse. The method for co-producing 2,3,3,3-tetrafluoropropene and hydrogen chloride by cyclic reuse is as follows: the raw materials are gasified and enter the first fluorination reactor; the mixture obtained at the outlet of the first fluorination reactor enters the hydrogen chloride I tower to separate hydrogen chloride, and the obtained mixture is introduced into the second fluorination reactor; the mixture obtained at the outlet of the second fluorination reactor enters the deacidification tower, and the mixture obtained at the bottom of the tower is returned to the inlet of the second fluorination reactor for cyclic reuse for multiple times; hydrogen chloride is obtained at the top of the deacidification tower; 2,3,3,3-tetrafluoropropene is obtained at the bottom of the tower. The method for co-producing 2,3,3,3-tetrafluoropropene and hydrogen chloride by cyclic reuse provided by the present invention has a closed-loop reaction in the whole system, co-produces 2,3,3,3-tetrafluoropropene and hydrogen chloride, has a high yield, and a simple process flow.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation methods of refrigerants, and particularly relates to a method for co-producing 2,3,3,3-tetrafluoropropene and hydrogen chloride by cyclic reuse. Background Art

[0002] 2,3,3,3-Tetrafluoropropene (HFO-1234yf), English name: 2,3,3,3-Tetrafluoropropylene, is a colorless gas. As a single-component refrigerant, it has excellent environmental parameters, ODP = 0, GWP = 4, boiling point of -29.5°C, and an atmospheric lifetime of 10 days. It can be used as a refrigerant, fire extinguishing agent, propellant, foaming agent, carrier fluid, polishing and grinding agent, and working fluid for power cycles.

[0003] 1,1,1,2-Tetrafluoroethane (HFC-134a) is currently the mainstream refrigerant for automotive air conditioners. However, it has a relatively high greenhouse effect (GWP = 1300) and a long atmospheric lifetime. Its large-scale use will cause global warming, and it has also entered the countdown stage. HFO-1234yf is considered the best alternative for the new generation of automotive refrigerants.

[0004] The synthesis technology of HFO-1234yf has attracted more and more attention. The existing synthesis technologies mainly have the following routes: (1) using monochloromethane and tetrafluoroethylene or monochlorodifluoromethane as raw materials; (2) using a mixture of HFC-236ea and HFC-245eb as raw materials; (3) using HCFC-225ca as raw materials; (4) using tetrafluoroethylene and trichlorofluoromethane as raw materials; (5) using HFC-1225ye as raw materials; (6) using hexafluoropropene as raw materials; (7) using 1,1,2,3-tetrachloropropene (TCP) as raw materials. However, the process routes most commonly used in industry are the hexafluoropropene method and the 1,1,2,3-tetrachloropropene method.

[0005] CN103534228A discloses a method for manufacturing 1234yf from TCP in three integrated steps: (a) R-1 hydrofluorination of TCP in the gas phase to form 1233xf; (b) R-2 hydrofluorination of either in the liquid phase or subsequently in the gas phase to form 244bb; and (c) R-3 dehydrochlorination of 244bb in the liquid or gas phase to prepare 1234yf. In the second and third steps of the synthesis route of this invention, liquid-phase fluorination is used, resulting in a large amount of waste alkali liquor, which is not conducive to industrial projects.

[0006] CN104151131B discloses a method for preparing 2,3,3,3-tetrafluoropropene. First, hydrogen fluoride and 1,1,2,3-tetrachloropropene are vaporized by heating and then introduced into a first reactor, where they react under the action of a type A catalyst to obtain a mixed product containing 2,3-dichloro-3,3-difluoropropene. Then, the mixed product containing 2,3-dichloro-3,3-difluoropropene is preheated and introduced into a second reactor, where it reacts under the action of a type B catalyst to obtain a mixed product containing 2,3,3,3-tetrafluoropropene. The impurities are separated to obtain the 2,3,3,3-tetrafluoropropene product. The two-step gas-phase method is adopted for synthesis, but the intermediate product is 2,3-dichloro-3,3-difluoropropene, and a chloride raw material, 1,1,2,3-tetrachloropropene, is used.

[0007] CN102686543A discloses the catalytic gas-phase fluorination of 1230xa to 1234yf. The method includes: contacting 1,1,2,3-tetrachloropropene (1230xa) with hydrogen fluoride HF in the gas phase in the presence of a fluorination catalyst under conditions sufficient to produce a reaction mixture; separating the reaction mixture into a first stream including HCl and 2,2,2,3-tetrafluoropropene (1234yf) and a second stream including HF, 2-chloro-3,3,3-trifluoro-1-propene (1233xf), and 1,1,1,2,2-pentafluoropropane (245cb); and recycling at least a portion of the second stream at least partially back to the step.

[0008] CN101597209A discloses an integrated method for preparing 2,3,3,3-tetrafluoropropene, including: providing a starting composition including at least one compound having a structure selected from Formulas I, II, and III: CX2=CCl-CH2X (Formula I); CX3-CCl=CH2 (Formula II); CX3-CHCl-CH2X (Formula III); reacting the starting composition with a first fluorination reagent to generate a first intermediate composition including 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf) and a first chlorine-containing byproduct; contacting the first intermediate composition with a second fluorination reagent to generate a second intermediate composition including 2-chloro-1, ,1,2-tetrafluoropropane (HFC-244bb) and a second chlorine-containing byproduct; and catalytically dehydrochlorinating at least a portion of HFC-244bb to generate a reaction product including HFO-1234yf.

[0009] CN102001911A discloses a method for preparing 2,3,3,3-tetrafluoropropene. a In the presence of a fluorination catalyst, hydrogen fluoride, 1,1,1,2,2-pentachloropropane or 2,3,3,3-tetrachloropropene enter the first reactor for reaction; in the presence of a fluorination catalyst, 2-chloro-3,3,3-trifluoropropene, 2-chloro-1,1,1,2-tetrafluoropropane and 1,1,1,2,2-pentafluoropropane react with hydrogen fluoride in the second reactor; c The product stream from step a enters the first distillation column for separation, the overhead components are separated from the reaction system, and the bottom components enter the phase separator; d The lower layer components of the phase separator are recycled to the first reactor, and the upper layer light components of the phase separator and the product stream from step b enter the second distillation column for separation; e The bottom components of the second distillation column are recycled to the second reactor, and the overhead components enter the third distillation column for separation; f The bottom components of the third distillation column are recycled to the second reactor, and the overhead components are separated from the reaction system. Summary of the Invention

[0010] The technical problem to be solved by the present invention is to overcome the deficiencies existing in the prior art and provide a method for preparing 2,3,3,3-tetrafluoropropene and hydrogen chloride by recycling and co-producing. The entire system has a closed-loop reaction, recycling and utilization, few by-products, co-producing 2,3,3,3-tetrafluoropropene and hydrogen chloride, high yield, double benefits, and a simple process flow.

[0011] The method for preparing 2,3,3,3-tetrafluoropropene and hydrogen chloride by recycling and co-producing according to the present invention includes the following steps:

[0012] (1) The raw materials hydrogen fluoride, 1,1,1,2,3-pentachloropropane and 1,1,2,3-tetrachloropropene are vaporized and then enter the first fluorination reactor, and react under the action of catalyst A to obtain a mixture of 2,3-dichloro-3,3-difluoropropene, 2-chloro-3,3,3-trifluoropropene, 1,1,1,2,2-pentafluoropropane, hydrogen chloride and unreacted hydrogen fluoride;

[0013] (2) The mixture obtained at the outlet of the first fluorination reactor enters the hydrogen chloride I column. After separating hydrogen chloride, the obtained 2,3-dichloro-3,3-difluoropropene, 2-chloro-3,3,3-trifluoropropene, 1,1,1,2,2-pentafluoropropane and unreacted hydrogen fluoride are introduced into the second fluorination reactor, and react under the action of catalyst B to obtain 2,3,3,3-tetrafluoropropene, hydrogen chloride, unreacted 2-chloro-3,3,3-trifluoropropene, 1,1,1,2,2-pentafluoropropane and a hydrogen fluoride mixture;

[0014] (3) Feed the mixture obtained from the outlet of the second fluorination reactor into the deacidification column. A mixture of 2,3,3,3-tetrafluoropropene and hydrogen chloride is obtained at the top of the column, and a mixture of 2-chloro-3,3,3-trifluoropropene, 1,1,1,2,2-pentafluoropropane and hydrogen fluoride obtained at the bottom of the column is returned to the inlet of the second fluorination reactor and recycled multiple times.

[0015] (4) Feed the mixture of 2,3,3,3-tetrafluoropropene and hydrogen chloride obtained at the top of the deacidification column into the hydrogen chloride II column. After separation, hydrogen chloride is obtained at the top of the column; 2,3,3,3-tetrafluoropropene and a small amount of acidic substances are obtained at the bottom of the column, and 2,3,3,3-tetrafluoropropene is obtained after post-treatment.

[0016] The reaction temperature of step (1) is 150 - 250 °C, preferably 200 - 230 °C, the residence time is 5 - 20 s, preferably 10 - 15 s, and the pressure is 0.5 - 0.9 MPa, preferably 0.7 - 0.8 MPa. In step (1), the first fluorination reactor is a shell-and-tube type or an adiabatic type, with the material being 16Mn or 316L, and the second fluorination reactor is a shell-and-tube type, with the material being Inconel600 or Hastally.

[0017] The catalyst A in step (1) is chromium and magnesium supported on alumina, with the chromium loading being 15 - 25 wt% and the magnesium loading being 1 - 3 wt%.

[0018] The molar ratio of hydrogen fluoride to the mixture of 1,1,1,2,3-pentachloropropane and 1,1,2,3-tetrachloropropene in step (1) is (5 - 7):1.

[0019] The top temperature of the hydrogen chloride I column in step (2) is -35 to -50 °C, and the pressure is 0.7 - 0.8 MPa.

[0020] The reaction temperature of the second fluorination reactor in step (2) is 350 - 450 °C, preferably 400 - 420 °C, the residence time is 20 - 50 s, preferably 35 - 40 s, and the pressure is 0.8 - 1.3 MPa, preferably 1.0 - 1.1 MPa. The second fluorination reactor in step (2) is a shell-and-tube type, with the material being Inconel600 or Hastally.

[0021] The catalyst B in step (2) is amorphous chromium oxide, which is prepared by the co-precipitation method.

[0022] The top temperature of the deacidification column in step (3) is 100 - 150 °C, and the pressure is 0.9 - 1.2 MPa.

[0023] The top temperature of the hydrogen chloride II column in step (4) is -35 to -50 °C, and the pressure is 0.7 - 0.8 MPa.

[0024] The post-treatment of step (4) is washing with water in a water washing tower, caustic washing in a caustic washing tower, and drying.

[0025] Specifically, the method for co-producing 2,3,3,3-tetrafluoropropene and hydrogen chloride by recycling and applying includes the following steps:

[0026] (1) Hydrogen fluoride, 1,1,1,2,3-pentachloropropane, and 1,1,2,3-tetrachloropropene as raw materials are vaporized and then enter the first fluorination reactor. The reaction temperature is 150 - 250 °C, the molar ratio of hydrogen fluoride to the mixture of 1,1,1,2,3-pentachloropropane and 1,1,2,3-tetrachloropropene is 5 - 7:1, the residence time is 5 - 20 s, the pressure is 0.5 - 0.9 MPa, and the catalyst is chromium and magnesium supported on alumina. The reaction yields 2,3-dichloro-3,3-difluoropropene (HCFO-1232xf), 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf), 1,1,1,2,2-pentafluoropropane (HFC-245cb), and a small amount of the product HFO-1234yf, a mixture of hydrogen chloride and unreacted hydrogen fluoride;

[0027] (2) The mixture obtained at the outlet of the first fluorination reactor enters the hydrogen chloride I tower. The top temperature of the tower is -35 - -50 °C, the pressure is 0.7 - 0.8 MPa. After separating hydrogen chloride, the mixture containing 2,3-dichloro-3,3-difluoropropene, 2-chloro-3,3,3-trifluoropropene, 1,1,1,2,2-pentafluoropropane, and unreacted hydrogen fluoride is introduced into the second fluorination reactor. The reaction temperature is 350 - 450 °C, the residence time is 20 - 50 s, the pressure is 0.8 - 1.3 MPa, and the catalyst is amorphous chromium oxide. The reaction yields a mixture containing 2,3,3,3-tetrafluoropropene, hydrogen chloride, unreacted 2-chloro-3,3,3-trifluoropropene, 1,1, ,2,2-pentafluoropropane, and hydrogen fluoride;

[0028] (3) The mixture obtained at the outlet of the second fluorination reactor enters the deacidification tower. The top temperature of the tower is 100 - 150 °C, the pressure is 0.9 - 1.2 MPa. 2,3,3,3-tetrafluoropropene and hydrogen chloride are obtained at the top of the tower, and 2-chloro-3,3,3-trifluoropropene, 1,1,1,2,2-pentafluoropropane, and hydrogen fluoride are obtained at the bottom of the tower, which are returned to the inlet of the second fluorination reactor and recycled multiple times;

[0029] (4) The mixture obtained at the top of the deacidification tower in step (3) enters the hydrogen chloride II tower for separation. The top temperature of the tower is -35 - -50 °C, the pressure is 0.7 - 0.8 MPa. Hydrogen chloride is obtained at the top of the tower; 2,3,3,3-tetrafluoropropene and a small amount of acidic substances are obtained at the bottom of the tower. After passing through a water washing tower, a caustic washing tower, and drying, the product 2,3,3,3-tetrafluoropropene (HFO-1234yf) is obtained.

[0030] In the above steps, after the first fluorination reactor and the second fluorination reactor are filled with the catalyst, they are both heated up and HF is introduced for fluorination, and then the above reactions are carried out.

[0031] The reaction equations for the co-production of 2,3,3,3-tetrafluoropropene and hydrogen chloride by recycling and reuse in the present invention are as follows:

[0032]

[0033]

[0034]

[0035]

[0036]

[0037]

[0038] In the first fluorination reactor of step (1) of the present invention, the addition and fluoro-chloro exchange reaction of TCP and 1,1,1,2,3-pentachloropropane first occur to generate organic compounds such as HCFO-1232xf, HCFO-1233xf, and HFC-245cb. Under the action of an alumina-supported chromium and magnesium catalyst, the conversion rates of TCP and 1,1,1,2,3-pentachloropropane are nearly 100%. The activity of the catalyst is adjusted according to the chromium content loaded. The activity is good in the initial stage of the reaction, and the amount of HCFO-1232xf generated is small, while the contents of HCFO-1233xf and HFC-245cb are large. The reaction needs to control the temperature and molar ratio to prevent the catalyst from being deactivated due to rapid carbon deposition while ensuring the conversion rate. The preferred reaction temperature is 200-230 °C, the molar ratio of hydrogen fluoride to 1,1,1,2,3-pentachloropropane and 1,1,2,3-tetrachloropropene is 5-7:1, the residence time is 10-15 s, and the pressure is 0.7-0.8 MPa.

[0039] In the second fluorination reactor of step (2) of the present invention, a fluoro-chloro exchange reaction and a dehydrofluorination reaction occur. The reaction of HCFO-1233xf and hydrogen fluoride to form HFO-1234yf is a reversible reaction. The reaction of HFC-245fa to remove HF to form HFO-1234yf needs to be carried out at a high temperature. The catalyst is selected as amorphous chromium oxide with a high specific surface area and pore volume. The preferred reaction temperature is 350-450 °C, the residence time is 20-50 s, and the pressure is 0.8-1.3 MPa.

[0040] The main reasons for catalyst deactivation are carbon deposition and poisoning, which lead to a decrease in the specific surface area and micropores of the catalyst. Carbon deposition can restore the catalyst activity through regeneration methods. However, trace poisons such as arsenic and sulfur in the raw materials can cause permanent deactivation of the catalyst. The impregnation method is selected for the preparation of the catalyst in the first fluorination reactor. The alumina support is impregnated in a chromium and magnesium solution of a certain concentration, dried, calcined, and fluorinated with HF after reaching a certain loading amount to obtain the catalyst. The catalyst used in the second fluorination reactor can be prepared by the co-precipitation method known in the art. Chromium and other auxiliary salts react with the precipitant to form a solid suspension of hydroxides, which is filtered, washed, roller-milled, dried, granulated, calcined, tableted, and fluorinated to obtain the catalyst. The first fluorination reactor is of the shell-and-tube type or adiabatic type, with a material of 16Mn or 316L. After HF is completely vaporized, the corrosion of the reactor is reduced, and the reactor can maintain a service life of more than 4 years. Since it is a strongly exothermic reaction, the shell-and-tube reactor type is preferred. However, the production capacity is low. If high production capacity is pursued, the adiabatic type can be considered, and the fluorination regeneration cycle is long. The second fluorination reactor is of the shell-and-tube type, and the catalyst can be effectively utilized. The material of the reactor can be selected from acid-resistant corrosion materials such as Inconel600 or Hastally, and it can maintain a service life of more than 10 years.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] (1) By using the method of cyclic reuse and co-production of 2,3,3,3-tetrafluoropropene and hydrogen chloride of the present invention, hydrogen chloride and 2,3,3,3-tetrafluoropropene are co-produced simultaneously, and the preparation yield is high.

[0043] (2) In the method for preparing 2,3,3,3-tetrafluoropropene and hydrogen chloride of the present invention, the cyclic reuse method is adopted throughout the process. TCP and 1,1,1,2,3-pentachloropropane do not need to be separated and are directly mixed for reaction, with a conversion rate of 100%, and the process flow is simple.

[0044] (3) In the method for preparing 2,3,3,3-tetrafluoropropene and hydrogen chloride by cyclic reuse of the present invention, after the high-temperature reaction in the second fluorination reactor, under the catalyst B and reaction conditions, the target product has a high yield and few by-products.

[0045] (4) In the method for preparing 2,3,3,3-tetrafluoropropene and hydrogen chloride by cyclic reuse of the present invention, the material at the outlet of the second fluorination reactor directly enters the deacidification tower. After separating heavy components such as HCFO-1233xf, HFC-245cb, and HF, it then enters the hydrogen chloride II tower to separate and obtain HCl and the product HFO-1234yf, reducing the energy consumption of separation. Description of the Drawings

[0046] Figure 1Process flow diagram of the method for co-producing 2,3,3,3-tetrafluoropropene and hydrogen chloride by recycling in the present invention;

[0047] In the figure: 1. First fluorination reactor; 2. Hydrogen chloride I tower; 3. Second fluorination reactor; 4. Deacidification tower; 5. Hydrogen chloride II tower; 6. Water washing tower; 7. Alkali washing tower; 8. Drying tower. Specific embodiments

[0048] The present invention will be further described in detail below in conjunction with embodiments, but the present invention is not limited to the following embodiments.

[0049] As Figure 1 shown, raw materials HF, TCP and 1,1,1,2,3-pentachloropropane enter the first fluorination reactor for reaction. The reactor outlet containing HCFO-1232xf, HCFO-1233xf, HFC-245cb, HCl and HF logistics enters the HCl I tower. HCl is separated at the top of the tower, and the tower bottom containing HCFO-1232xf, HCFO-1233xf, HFC-245cb and HF logistics enters the second fluorination reactor. The reactor outlet containing HFO-1234yf, HCFO-1233xf, HFC-245cb, HCl and a small amount of HF logistics enters the deacidification tower. The tower bottom obtains a logistics containing HCFO-1233xf, HFC-245cb and a small amount of HF, which is returned to the second fluorination reactor. The logistics containing HFO-1234yf and HCl at the top of the tower enters the HCl II tower. HCl is obtained at the top of the tower, and the tower bottom logistics enters the water washing tower, alkali washing tower and drying tower to obtain the product HFO-1234yf.

[0050] The method for co-producing 2,3,3,3-tetrafluoropropene and hydrogen chloride by recycling includes the following steps:

[0051] (1) Hydrogen fluoride, 1,1,1,2,3-pentachloropropane and 1,1,2,3-tetrachloropropene are vaporized and enter the first fluorination reactor. The reaction temperature is 150-250 °C, the molar ratio of hydrogen fluoride to the mixture of 1,1,1,2,3-pentachloropropane and 1,1,2,3-tetrachloropropene is 5-7:1, the residence time is 5-20 s, the pressure is 0.5-0.9 MPa, and the catalyst is chromium and magnesium supported on alumina. The reaction obtains 2,3-dichloro-3,3-difluoropropene (HCFO-1232xf), 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf), 1,1,1,2,2-pentafluoropropane (HFC-245cb), and a small amount of the product HFO-1234yf, a mixture of hydrogen chloride and unreacted hydrogen fluoride;

[0052] (2) Feed the mixture obtained at the outlet of the first fluorination reactor into the hydrogen chloride I tower. The top temperature of the tower is -35 to -50 °C, and the pressure is 0.7 - 0.8 MPa. After separating hydrogen chloride, feed the mixture containing 2,3-dichloro-3,3-difluoropropene, 2-chloro-3,3,3-trifluoropropene, 1,1,1,2,2-pentafluoropropane, and unreacted hydrogen fluoride into the second fluorination reactor. The reaction temperature is 350 - 450 °C, the residence time is 20 - 50 s, the pressure is 0.8 - 1.3 MPa, and the catalyst is amorphous chromium oxide. The reaction yields a mixture containing 2,3,3,3-tetrafluoropropene, hydrogen chloride, unreacted 2-chloro-3,3,3-trifluoropropene, 1,1,1,2,2-pentafluoropropane, and hydrogen fluoride;

[0053] (3) Feed the mixture obtained at the outlet of the second fluorination reactor into the deacidification tower. The top temperature of the tower is 100 - 150 °C, and the pressure is 0.9 - 1.2 MPa. 2,3,3,3-tetrafluoropropene and hydrogen chloride are obtained at the top of the tower, and 2-chloro-3,3,3-trifluoropropene, 1,1,1,2,2-pentafluoropropane, and hydrogen fluoride are obtained at the bottom of the tower, which are returned to the inlet of the second fluorination reactor and recycled multiple times;

[0054] (4) Feed the mixture obtained at the top of the deacidification tower in step (3) into the hydrogen chloride II tower for separation. The top temperature of the tower is -35 to -50 °C, and the pressure is 0.7 - 0.8 MPa. Hydrogen chloride is obtained at the top of the tower; 2,3,3,3-tetrafluoropropene and a small amount of acidic substances are obtained at the bottom of the tower. After passing through a water washing tower, an alkali washing tower, and drying, the product 2,3,3,3-tetrafluoropropene (HFO-1234yf) is obtained.

[0055] Example 1

[0056] Using the above steps, the process parameters for continuous recycling and the organic matter content at the outlets of the first fluorination reactor and the second fluorination reactor are shown in Table 1. The first fluorination reactor is filled with 20 ml of alumina-supported chromium and magnesium, the chromium loading is 15 wt%, the magnesium loading is 3 wt%, heated to 380 °C, and HF is introduced for fluorination. The HF flow rate is 20 ml / min, and the moisture content at the reactor outlet is <50 ppm; the second fluorination reactor is filled with 50 ml of chromium oxide, heated to 400 °C, and HF is introduced for fluorination. The HF flow rate is 50 ml / min, and the moisture content at the reactor outlet is <50 ppm.

[0057] Control the top temperature of the hydrogen chloride I tower at -35 to -50 °C and the pressure at 0.7 - 0.8 MPa, control the top temperature of the deacidification tower at 100 - 150 °C and the pressure at 0.9 - 1.2 MPa, and control the top temperature of the hydrogen chloride II tower at -35 to -50 °C and the pressure at 0.7 - 0.8 MPa. Specific adjustments for each recycling can be made according to the material composition at the outlet of the fluorination reactor.

[0058] Table 1 Process parameters for cyclic application and organic matter content at the outlets of the first and second fluorination reactors

[0059]

[0060]

[0061] Example 2

[0062] Using the above steps, the process parameters for continuous application and the organic matter content at the outlets of the first and second fluorination reactors are shown in Table 2. The first fluorination reactor is filled with 20 ml of alumina supported chromium and magnesium, with a chromium loading of 20 wt% and a magnesium loading of 3 wt%. It is heated to 380 °C and HF is introduced for fluorination. The HF flow rate is 20 ml / min, and the moisture content at the reactor outlet is < 50 ppm. The second fluorination reactor is filled with 50 ml of chromium oxide, heated to 400 °C, and HF is introduced for fluorination. The HF flow rate is 50 ml / min, and the moisture content at the reactor outlet is < 50 ppm.

[0063] The top temperature of the hydrogen chloride I tower is controlled at -35 to -50 °C, and the pressure is 0.7 - 0.8 MPa. The top temperature of the deacidification tower is controlled at 100 to 150 °C, and the pressure is 0.9 - 1.2 MPa. The top temperature of the hydrogen chloride II tower is controlled at -35 to -50 °C, and the pressure is 0.7 - 0.8 MPa. Specific adjustments can be made for each application according to the material composition at the outlet of the fluorination reactor.

[0064] Table 2 Process parameters for cyclic application and organic matter content at the outlets of the first and second fluorination reactors

[0065]

[0066] Example 3

[0067] Using the above steps, the process parameters for continuous application and the organic matter content at the outlets of the first and second fluorination reactors are shown in Table 3. The first fluorination reactor is filled with 20 ml of alumina supported chromium and magnesium, with a chromium loading of 25 wt% and a magnesium loading of 2 wt%. It is heated to 380 °C and HF is introduced for fluorination. The HF flow rate is 20 ml / min, and the moisture content at the reactor outlet is < 50 ppm. The second fluorination reactor is filled with 50 ml of chromium oxide, heated to 400 °C, and HF is introduced for fluorination. The HF flow rate is 50 ml / min, and the moisture content at the reactor outlet is < 50 ppm.

[0068] The control of the top temperature of the hydrogen chloride column I is -35 to -50 °C, and the pressure is 0.7 - 0.8 MPa. The control of the top temperature of the deacidification column is 100 to 150 °C, and the pressure is 0.9 - 1.2 MPa. The control of the top temperature of the hydrogen chloride column II is -35 to -50 °C, and the pressure is 0.7 - 0.8 MPa. Specific corresponding adjustments can be made for each application according to the material composition at the outlet of the fluorination reactor.

[0069] Table 3 Process parameters for recycling and the organic matter content at the outlets of the first and second fluorination reactors

[0070]

[0071] Example 4

[0072] Using the above steps, the process parameters for continuous recycling and the organic matter content at the outlets of the first and second fluorination reactors are shown in Table 4. The first fluorination reactor is filled with 20 ml of alumina supported chromium and magnesium, the chromium loading is 20 wt%, and the magnesium loading is 2 wt%. It is heated to 380 °C and HF is introduced for fluorination. The HF flow rate is 20 ml / min, and the moisture content at the reactor outlet is < 50 ppm. The second fluorination reactor is filled with 50 ml of chromium oxide, heated to 400 °C, and HF is introduced for fluorination. The HF flow rate is 50 ml / min, and the moisture content at the reactor outlet is < 50 ppm.

[0073] The control of the top temperature of the hydrogen chloride column I is -35 to -50 °C, and the pressure is 0.7 - 0.8 MPa. The control of the top temperature of the deacidification column is 100 to 150 °C, and the pressure is 0.9 - 1.2 MPa. The control of the top temperature of the hydrogen chloride column II is -35 to -50 °C, and the pressure is 0.7 - 0.8 MPa. Specific corresponding adjustments can be made for each application according to the material composition at the outlet of the fluorination reactor.

[0074] Table 4 Process parameters for recycling and the organic matter content at the outlets of the first and second fluorination reactors

[0075]

[0076]

[0077] Through the above examples and the method of co-producing 2,3,3,3-tetrafluoropropene and hydrogen chloride by recycling, it can be seen that the material conversion rate of the present invention is 100%. There is no waste or separation phenomenon in the process flow. At the same time, high-yield hydrogen chloride and the product 2,3,3,3-tetrafluoropropene are obtained. The yield is high, the energy consumption is low, and the double benefits are increased, expanding its market application.

[0078] Certainly, the above content is only a preferred embodiment of the present invention and cannot be considered as limiting the scope of the embodiments of the present invention. The present invention is not limited to the above examples either. Equivalent changes and improvements made by those of ordinary skill in the art within the essence of the present invention shall fall within the scope covered by the patent of the present invention.

Claims

1. A method for co-producing 2,3,3,3-tetrafluoropropene and hydrogen chloride by cyclic application, characterized in that: It includes the following steps: (1) Raw materials hydrogen fluoride, 1,1,1,2,3-pentachloropropane and 1,1,2,3-tetrachloropropene are vaporized and then enter the first fluorination reactor, and react under the action of catalyst A to obtain a mixture of 2,3-dichloro-3,3-difluoropropene, 2-chloro-3,3,3-trifluoropropene, 1,1,1,2,2-pentafluoropropane, hydrogen chloride and unreacted hydrogen fluoride; catalyst A is alumina supported chromium and magnesium, the chromium loading is 15-25 wt%, and the magnesium loading is 1-3 wt%; (2) The mixture obtained at the outlet of the first fluorination reactor enters the hydrogen chloride I tower. After separating hydrogen chloride, the obtained 2,3-dichloro-3,3-difluoropropene, 2-chloro-3,3,3-trifluoropropene, 1,1,1,2,2-pentafluoropropane and unreacted hydrogen fluoride are introduced into the second fluorination reactor and react under the action of catalyst B to obtain a mixture of 2,3,3,3-tetrafluoropropene, hydrogen chloride, unreacted 2-chloro-3,3,3-trifluoropropene, 1,1,1,2,2-pentafluoropropane and hydrogen fluoride; catalyst B is amorphous chromium oxide; The top temperature of the hydrogen chloride I tower is -35 to -50 °C, and the pressure is 0.7 - 0.8 MPa; the reaction temperature of the second fluorination reactor is 350 - 450 °C, the residence time is 20 - 50 s, and the pressure is 0.8 - 1.3 MPa; (3) The mixture obtained at the outlet of the second fluorination reactor enters the deacidification tower. A mixture of 2,3,3,3-tetrafluoropropene and hydrogen chloride is obtained at the top of the tower, and the mixture of 2-chloro-3,3,3-trifluoropropene, 1,1,1,2,2-pentafluoropropane and hydrogen fluoride obtained at the bottom of the tower is returned to the inlet of the second fluorination reactor and recycled multiple times; (4) The mixture of 2,3,3,3-tetrafluoropropene and hydrogen chloride obtained at the top of the deacidification tower enters the hydrogen chloride II tower. After separation, hydrogen chloride is obtained at the top of the tower; 2,3,3,3-tetrafluoropropene and a small amount of acidic substances are obtained at the bottom of the tower, and 2,3,3,3-tetrafluoropropene is obtained after post-treatment.

2. The method for co-producing 2,3,3,3-tetrafluoropropene and hydrogen chloride by cyclic application according to claim 1, characterized in that: The reaction temperature of step (1) is 150 - 250 °C, the residence time is 5 - 20 s, and the pressure is 0.5 - 0.9 MPa.

3. The method for co-producing 2,3,3,3-tetrafluoropropene and hydrogen chloride by cyclic application according to claim 1, characterized in that: The molar ratio of hydrogen fluoride to the mixture of 1,1,1,2,3-pentachloropropane and 1,1,2,3-tetrachloropropene in step (1) is (5 - 7):

1.

4. The method for co-producing 2,3,3,3-tetrafluoropropene and hydrogen chloride by cyclic application according to claim 1, wherein: The top temperature of the deacidification tower in step (3) is 100 - 150 °C, and the pressure is 0.9 - 1.2 MPa.

5. The method for co-producing 2,3,3,3-tetrafluoropropene and hydrogen chloride by cyclic application according to claim 1, characterized in that: The top temperature of the hydrogen chloride II tower in step (4) is -35 to -50 °C, and the pressure is 0.7 - 0.8 MPa.

6. The method for co-producing 2,3,3,3-tetrafluoropropene and hydrogen chloride by cyclic application according to claim 1, characterized in that: The post-treatment in step (4) is washing with water in a water washing tower, washing with alkali in an alkali washing tower, and drying.

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