CN112537997B - Method and device for co-production of 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene - Google Patents

Method and device for co-production of 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene Download PDF

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CN112537997B
CN112537997B CN202011426865.6A CN202011426865A CN112537997B CN 112537997 B CN112537997 B CN 112537997B CN 202011426865 A CN202011426865 A CN 202011426865A CN 112537997 B CN112537997 B CN 112537997B
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trifluoropropene
tower
rectification
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CN112537997A (en
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解乐福
邵军强
丛飞
田志钢
杜辉
周建民
李成林
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Weihai Xinyuan New Material Co ltd
Xinyuan Chemical Shandong Co ltd
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WEIHAI NEWERA CHEMICAL CO Ltd
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    • C07C17/00—Preparation of halogenated hydrocarbons
    • C07C17/093—Preparation of halogenated hydrocarbons by replacement by halogens
    • C07C17/20—Preparation of halogenated hydrocarbons by replacement by halogens of halogen atoms by other halogen atoms
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C17/00—Preparation of halogenated hydrocarbons
    • C07C17/013—Preparation of halogenated hydrocarbons by addition of halogens
    • C07C17/04—Preparation of halogenated hydrocarbons by addition of halogens to unsaturated halogenated hydrocarbons
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C17/00—Preparation of halogenated hydrocarbons
    • C07C17/25—Preparation of halogenated hydrocarbons by splitting-off hydrogen halides from halogenated hydrocarbons
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C17/00—Preparation of halogenated hydrocarbons
    • C07C17/38—Separation; Purification; Stabilisation; Use of additives
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C17/00—Preparation of halogenated hydrocarbons
    • C07C17/38—Separation; Purification; Stabilisation; Use of additives
    • C07C17/383—Separation; Purification; Stabilisation; Use of additives by distillation

Abstract

The invention relates to a method and a device for co-producing 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene, wherein the device used in the method comprises a reaction system, a rectification pre-separation system and an azeotrope-like extraction separation system; the raw material premixer adopts a falling film evaporation premixer to promote the rapid and sufficient vaporization of the liquid material 1,1,1, 3-tetrachloropropane and enhance the mixing effect of various gas-phase materials. The rectification pre-separation system adopts a three-tower continuous rectification mode to realize the high-efficiency separation of reaction by-product hydrogen chloride, high-boiling-point substances and excessive hydrogen fluoride. The azeotrope-like extraction separation system realizes the liquid-liquid two-phase extraction separation of azeotrope-like substances. The production method provided by the invention is realized by the production device with the specific structure and the connection relation, has the advantages of mild reaction conditions, high reaction rate, good atom economy, stable product quality, adjustable product proportion and the like, can realize automatic control of the whole flow, saves labor, and is suitable for industrial co-production of 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene.

Description

Method and device for co-production of 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene
Technical Field
The invention relates to a method and a device for preparing fluorine-containing olefin and fluorine-containing chloro olefin, in particular to a method and a device for co-producing 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene.
Background
3,3, 3-trifluoropropene is a basic raw material for synthesizing high value-added organic compounds such as 2-bromo-3, 3, 3-trifluoropropene (BTP), fluorosilicone rubber and the like. The 2-bromine-3, 3, 3-trifluoropropene is degradable bromohydrocarbon, is a novel clean efficient fire extinguishing agent, has ozone consumption potential (0.0028) and global warming potential (0.005) far lower than Halon series fire extinguishing agents (7.1 and 1890), is easy to degrade in the environment, has the advantages of rapid fire extinguishing, cleanness, high efficiency, non-conductivity and the like when being used as the fire extinguishing agent, and is a new substitute of the traditional Halon fire extinguishing agent. The fluorosilicone rubber not only has the performance of resisting high and low temperatures (-55-205 ℃) of the silicon rubber, but also has the characteristics of fuel oil resistance, chemical corrosion resistance and the like of the fluororubber, and is one of the synthetic rubbers with the best comprehensive performance in the world at present. The composite material is widely applied to the fields of aviation, aerospace, automobiles, medicine and the like.
2-chloro-3, 3, 3-trifluoropropene is an important precursor compound for the synthesis of the refrigerant HFO-1234 yf. Ozone depleting chlorofluorocarbons (CFCs) and Hydrochlorofluorocarbons (HCFCs) are being phased out according to the montreal protocol. In addition to ozone depletion issues, global warming is another important environmental issue. HFC-134a which is widely applied to automobile air conditioners, household electrical appliances and industrial and commercial refrigeration equipment at present and applied to the industries of foaming, fire extinguishing, aerosol, cleaning and the like has high global warming potential (GWP 1300) and long atmospheric service life, and a large amount of use can cause global warming, and the countdown phase is also entered. Therefore, the research and popularization of compounds that can simultaneously meet low ozone depletion standards and have low global warming potential has been the focus of the fluorocarbon industry. Among them, HFO-1234yf has been identified as a potential refrigerant, and HFO-1234yf can be used as a polymerization monomer and a comonomer of a rubber material with high thermal stability and high elasticity in addition to being used as a refrigerant, and has a large market capacity. With the wide popularization of HFC-1234yf, the 2-chloro-3, 3, 3-trifluoropropene used as a raw material is bound to generate great economic value and social value.
Currently, among the known production methods of 3,3, 3-trifluoropropene, the production using hydrofluorination is the most common method, for example, U.S. Pat. No. 4, 4465786A discloses a method for producing 3,3, 3-trifluoropropene by fluorinating 1,1,1, 3-tetrachloropropane, and a method for prolonging the life of the catalyst by adding a small amount of hexachloroethane and chlorine gas to the raw material, but the addition of hexachloroethane increases the difficulty of material purification. U.S. Pat. No. 3,9096489 also uses 1,1,1, 3-tetrachloropropane as raw material and hydrogen fluoride as fluorinating agent, and prepares 3,3, 3-trifluoropropene by catalytic fluorination in the presence of zinc/chromium oxide catalyst, and the preparation process of the catalyst in the method is difficult, requires high-temperature calcination above 500 ℃, and has high requirements on equipment. U.S. Pat. No. 4,08 describes a process for preparing 3,3, 3-trifluoropropene from one or more of 1,1,1, 3-tetrachloropropane, 1,1, 3-trichloropropene and 3,3, 3-trichloropropene by fluorination using hydrogen fluoride as a fluorinating agent under catalysis of a nitrogen-based catalyst to obtain 3,3, 3-trifluoropropene, which catalyst has the problems of difficult separation from the product, difficult regeneration and difficult industrial production. The preparation of 3,3, 3-trifluoropropene disclosed in US patent 10689316 employs a two-step process, the first step of which is a catalytic fluorination starting from 1,1,1, 3-tetrachloropropane, using HF as fluorinating agent, at a temperature of 20 ℃ to 100 ℃ to produce a liquid phase reaction product comprising 1-chloro-3, 3, 3-trifluoropropane. The second step is the dehydrochlorination of 1-chloro-3, 3, 3-trifluoropropane carried out at 250-350 deg.C under the action of catalyst to produce 3,3, 3-trifluoropropene. Although the difficulty of material separation is reduced by the two-step method, the number of operation steps is increased, the equipment investment is increased, and the industrial production is not facilitated.
Preparation of 2-chloro-3, 3, 3-trifluoropropeneKnown methods include methods of hydrofluorination with anhydrous hydrogen fluoride. For example, patent WO2008/054781 reports a process comprising fluorination of 1,1,2, 3-tetrachloropropene in the gas phase in the presence of a chromium-based catalyst. Since the catalytic activity tends to deteriorate as the reaction proceeds, if the reaction is continued for a longer time, the catalytic activity is decreased, resulting in a decrease in the selectivity of 2-chloro-3, 3, 3-trifluoropropene. U.S. Pat. No. 4,9902671 discloses the preparation of 2-chloro-3, 3, 3-trifluoropropene by gas phase fluorination of at least one compound of 1,1,2,3, 3-tetrachloropropene, 1,1,1,2, 3-pentachloropropane, starting from a fluorinated chromium oxide catalyst and a stabilizer such as benzenediol, which introduces a stabilizer to extend the catalyst lifetime to some extent, but the addition of a stabilizer complicates the isolation of the product. Chinese patent CN109651077 discloses a method for preparing 2-chloro-3, 3, 3-trifluoropropene, comprising: reacting anhydrous hydrogen fluoride with at least one chlorine-containing compound selected from chloropropanes and chloropropenes represented by a specific formula in a gas phase in the presence of a chromium atom-containing fluorination catalyst while heating, the reaction being carried out in the presence of molecular chlorine and under conditions such that the water content in the reaction system is less than 300 ppm. Chinese patent CN10847339A takes 2, 3-dichloro-1, 1, 1-trifluoropropane, 1,1,1,2, 3-pentachloropropane, 2,3,3, 3-tetrachloropropene and/or 1,1,2, 3-tetrachloropropene as raw materials and uses a fluorination catalyst AlF3Or fluorinated alumina, with HF in the gas phase to form a 2-chloro-3, 3, 3-trifluoropropene-based product. The two Chinese patents only pay attention to the preparation of 2-chloro-3, 3, 3-trifluoropropene, and other products such as 3,3, 3-trifluoropropene in the products are not effectively utilized, so that the atom economy is poor, and the total yield is not high. US patent 20140147343 discloses a catalyst-free process for preparing 2-chloro-3, 3, 3-trifluoropropene by low-temperature fluorination using hydrogen fluoride. The method is not suitable for industrial production due to slow reaction rate, long reaction time, severe high-pressure reaction conditions and the like.
Although some reports on the preparation methods of 3,3, 3-trifluoropropene or 2-chloro-3, 3, 3-trifluoropropene have been published, no reports on the co-production of 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene have been published yet, and more importantly, the methods have problems such as difficult separation, no regeneration of the catalyst, poor reaction atom economy, low yield, more reaction steps, complex reaction system, slow reaction rate, long reaction time, severe high-pressure reaction conditions, low product quality, difficulty in realizing industrial continuous large-scale production and the like. The method has the advantages of mild reaction conditions, environment-friendly process, high reaction rate, good atom economy, stable product quality and adjustable product proportion and can be used for industrial continuous large-scale co-production of 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene.
Disclosure of Invention
Aiming at the defects of the prior art, in particular to the problem that the existing preparation method of 3,3, 3-trifluoropropene or 2-chloro-3, 3, 3-trifluoropropene is difficult to realize high atom utilization rate, the invention provides a method and a device for industrial continuous large-scale co-production of 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene, which have the advantages of mild reaction conditions, environment-friendly process, high reaction rate, good atom economy, stable product quality and adjustable product proportion.
The technical scheme of the invention is as follows:
a co-production method of 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene comprises the following steps:
(1) reaction process
Preheating hydrogen fluoride, liquid chlorine and tetrachloropropane, then vaporizing and mixing, and reacting the vaporized and mixed materials under the action of a fluorination catalyst, wherein the reaction temperature is 240-300 ℃, and the reaction pressure is 1.0-1.3 MPa; after the reaction is finished, cooling the mixed material, and then performing rectification pre-separation;
(2) pre-separation by rectification
The cooled mixed material is subjected to multi-stage rectification, and an azeotrope-like mixture is obtained at the top of the rectification tower;
(3) azeotrope-like extraction separation
Adding 2-chloro-3, 3, 3-trifluoropropene serving as an extracting agent into the azeotrope-like mixture, fully mixing the mixture with the azeotrope-like mixture, cooling, standing for phase separation, and performing multi-stage rectification on the recombined phase separation after phase separation;
condensing the materials at the top of the rectifying tower, and then performing alkali washing to obtain a crude product of the 3,3, 3-trifluoropropene;
condensing and then performing alkali washing on the materials at the bottom of the rectifying tower to obtain a crude product of the 2-chloro-3, 3, 3-trifluoropropene.
According to the invention, preferably, the temperature of the vaporization mixing in the step (1) is 240-300 ℃, and the pressure of the vaporization mixing is 1.0-1.3 MPa;
preferably, the molar ratio of chlorine to 1,1,1, 3-tetrachloropropane is (1-5): 100; the chlorine can inhibit the decomposition of the raw material 1,1,1, 3-tetrachloropropane, inhibit the carbon deposition of the fluorination catalyst, prolong the service life of the catalyst, and adjust the output ratio of the product 2-chloro-3, 3, 3-trifluoropropene by adjusting the introduction amount of the chlorine;
preferably, the molar ratio of the hydrogen fluoride to the 1,1,1, 3-tetrachloropropane is (10-50): 1; excessive introduction of hydrogen fluoride gas effectively reduces the partial vaporization pressure of 1,1,1, 3-tetrachloropropane, so that 1,1,1, 3-tetrachloropropane is rapidly vaporized;
preferably, the vaporization mixing process is carried out in a falling film evaporation premixer, so that the continuous and rapid vaporization and the full mixing of the mixed materials are realized.
According to the present invention, it is preferable that the fluorination catalyst in the step (1) is a chromium-based fluorination catalyst.
Preferably, the reaction process is carried out in a fixed bed tubular reactor. The main reaction equation is as follows:
Figure BDA0002825255610000041
chlorine gas is added to the reaction process to produce 2-chloro-3, 3, 3-trifluoropropene, and the possible reaction equation is as follows:
Figure BDA0002825255610000042
according to the invention, preferably, the three-stage rectification of the first rectification tower, the second rectification tower and the third rectification tower is carried out in series in the step (2);
preferably, the first rectifying tower adopts positive pressure rectification, the pressure is 1.0-1.2MPa, materials at the top of the first rectifying tower flow back after being condensed by circulating water at the temperature of 5-10 ℃, hydrogen fluoride, chlorine, 3,3, 3-trifluoropropene and a 2-chloro-3, 3, 3-trifluoropropene mixture are extracted and continuously enter the middle liquid phase of the second rectifying tower for feeding, the uncondensed components of the materials at the top of the first rectifying tower are mainly hydrogen chloride and a small amount of chlorine and continuously enter the middle gas phase of the second rectifying tower for feeding, and high-boiling-point substances are continuously discharged from the bottom of the first rectifying tower and are treated as waste liquid;
the second rectifying tower is used for continuous positive pressure rectification, the pressure is 1.0-1.2MPa, materials at the top of the second rectifying tower are condensed at minus 30 ℃ to minus 35 ℃ and then flow back, and hydrogen chloride and a small amount of chlorine are extracted and enter a hydrogen chloride absorption device; continuously discharging a mixture of hydrogen fluoride, 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene from the bottom of the second rectifying tower and continuously inputting the mixture into the third rectifying tower;
and (3) continuously carrying out positive pressure rectification in a third rectifying tower at the pressure of 0.8-1.0MPa, condensing the materials at the top of the third rectifying tower by circulating water at the temperature of 5-10 ℃, refluxing, extracting azeotrope-like hydrogen fluoride, 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene, continuously discharging hydrogen fluoride at the bottom of the third rectifying tower, and returning to the step (1) for reuse.
According to the present invention, it is preferred that the extraction agent and the azeotrope-like mixture are thoroughly mixed in step (3) in a static mixer;
preferably, the cooling temperature is-30 ℃ to-35 ℃ after the full mixing, the temperature of the standing phase separation process is-30 ℃ to-35 ℃, and the pressure is 0.6MPa to 0.8 MPa;
preferably, the light component phase after standing and phase separation is returned to the third rectifying tower in the step (2) for reuse;
preferably, the heavy component phase separation comprises 3,3, 3-trifluoropropene, 2-chloro-3, 3, 3-trifluoropropene and a small amount of hydrogen fluoride, and the two-stage rectification of the heavy component phase separation is carried out in series by a fourth rectifying tower and a fifth rectifying tower;
the fourth rectifying tower adopts positive pressure rectification, the pressure is 0.6-1.0MPa, materials at the top of the fourth rectifying tower flow back after being condensed by circulating water at the temperature of 5-10 ℃, an azeotrope-like mixture is extracted and returned to an extracting agent to be mixed with the azeotrope-like mixture for use, and a mixture of 3,3, 3-trifluoropropene, 2-chloro-3, 3, 3-trifluoropropene is discharged from the bottom of the fourth rectifying tower and enters a fifth rectifying tower;
the fifth rectifying tower adopts positive pressure rectification, the pressure is 0.5-0.8MPa, materials at the top of the fifth rectifying tower are condensed by circulating water at the temperature of 5-10 ℃ and then flow back, a 3,3, 3-trifluoropropene crude product is extracted, and the 3,3, 3-trifluoropropene crude product is obtained after alkali washing; can be further rectified and purified to obtain a 3,3, 3-trifluoropropene product; and continuously outputting a 2-chloro-3, 3, 3-trifluoropropene crude product from the bottom of the fifth rectifying tower, cooling by circulating water at 5-10 ℃, returning one part of the crude product to the extraction agent for mixing with the azeotrope-like mixture, washing the other part of the crude product by alkali to obtain the 2-chloro-3, 3, 3-trifluoropropene crude product, and further rectifying and purifying to obtain the 2-chloro-3, 3, 3-trifluoropropene product.
According to the invention, the invention also provides a co-production device of 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene, which comprises a reaction system, a rectification pre-separation system and an azeotrope-like extraction separation system;
the reaction system comprises a hydrogen fluoride metering tank, a liquid chlorine metering tank, a tetrachloropropane metering tank, a hydrogen fluoride metering pump, a liquid chlorine metering pump, a tetrachloropropane metering pump, a hydrogen fluoride vaporizer, a liquid chlorine vaporizer, a tetrachloropropane preheater, a premixer, a reactor and a reaction cooler, wherein the hydrogen fluoride metering tank is communicated with a bottom feed inlet of the hydrogen fluoride vaporizer through the hydrogen fluoride metering pump, a top discharge outlet of the hydrogen fluoride vaporizer is communicated with a top gas phase feed inlet of the premixer, the liquid chlorine metering tank is communicated with a bottom feed inlet of the liquid chlorine vaporizer through the liquid chlorine metering pump, a top discharge outlet of the liquid chlorine vaporizer is communicated with a top gas phase feed inlet of the premixer, the tetrachloropropane metering tank is communicated with a bottom feed inlet of the tetrachloropropane preheater through the tetrachloropropane metering pump, a top discharge outlet of the tetrachloropropane preheater is communicated with a side top liquid feed inlet of the premixer, a bottom discharge outlet of the premixer is communicated, a discharge hole at the top of the reactor is communicated with a feed hole in the middle of the rectifying tower I through a reaction cooler;
the rectification pre-separation system comprises a rectification tower I, a rectification tower I condenser, a rectification tower II condenser, a rectification tower III condenser and a hydrogen fluoride recovery pump, wherein a gas phase discharge port at the top of the rectification tower I is communicated with a feed inlet of the rectification tower I condenser, a discharge port at the bottom of the rectification tower I is externally connected with a valve pipeline for continuously outputting waste liquid, a gas phase discharge port of the rectification tower I condenser is communicated with a gas phase feed inlet at the middle part of the rectification tower II, a liquid phase discharge port of the rectification tower I condenser is communicated with a liquid phase return port at the top of the rectification tower I, a liquid phase feed inlet at the middle part of the rectification tower II is communicated with a pipeline between the liquid phase discharge port of the rectification tower I condenser and the liquid phase return port at the top of the rectification tower I, the gas phase discharge port at the top of the rectification tower II is, a liquid phase discharge port of a condenser of the rectification II tower is communicated with a liquid phase return port at the top of the side of the rectification II tower, a discharge port at the bottom of the rectification II tower is communicated with a feed port at the middle part of a rectification III tower, a gas phase discharge port at the top of the rectification III tower is communicated with a feed port of a condenser of the rectification III tower, a liquid phase discharge port of the condenser of the rectification III tower is communicated with a liquid phase return port at the top of the side of the rectification III tower, a discharge port at the bottom of the rectification III tower is communicated with a feed port of a hydrogen fluoride vaporizer through a hydrogen fluoride recovery pump, and a pipeline between the liquid phase discharge port of the condenser of;
the azeotrope-like extraction separation system comprises a static mixer, a phase separation condenser, a phase separator, a light phase tank, a light phase material-pumping pump, a heavy phase material-pumping pump, a rectification IV tower condenser, a rectification V tower condenser, a tower bottom cooler, a 2-chloro-3, 3, 3-trifluoropropene crude product tank, a 2-chloro-3, 3, 3-trifluoropropene crude product material-pumping pump, a 3,3, 3-trifluoropropene caustic wash tower, a 3,3, 3-trifluoropropene crude product tank and a 2-chloro-3, 3, 3-trifluoropropene caustic wash tower, wherein a discharge port of the static mixer is communicated with a feed port in the middle of the phase separator through the phase separation condenser, a discharge port of the light phase at the top of the phase separator is communicated with a feed port of the light phase tank, a discharge port of the light phase tank is communicated with a feed port in the middle of the rectification III tower through the, a discharge port at the bottom of the phase separator is communicated with a feed port in the middle of the rectification IV tower through a heavy phase material-pumping pump, a gas phase discharge port at the top of the rectification IV tower is communicated with a feed port of a condenser of the rectification IV tower, a liquid phase discharge port of the condenser of the rectification IV tower is communicated with a liquid phase return port at the top of the rectification IV tower, a pipeline between the liquid phase discharge port of the condenser of the rectification IV tower and the liquid phase return port at the side of the rectification IV tower is communicated with a feed port in the middle of the rectification V tower, a gas phase discharge port at the top of the rectification V tower is communicated with a feed port of a condenser of the rectification V tower, a liquid phase discharge port of the condenser of the rectification V tower is communicated with a liquid phase return port at the top of the side of the rectification V tower, a pipeline between the liquid phase discharge port of the condenser of the rectification V tower and the liquid, a discharge port at the top of the 3,3, 3-trifluoropropene alkali wash tower is communicated with a feed port at the top of a 3,3, 3-trifluoropropene crude product tank, a valve pipeline is connected outside a discharge port at the bottom of the 3,3, 3-trifluoropropene alkali wash tower, waste alkali liquor is continuously output, a discharge port at the bottom of a rectification V tower is communicated with a feed port at the side of the 2-chloro-3, 3, 3-trifluoropropene crude product tank through a tower bottom cooler, a 2-chloro-3, 3, 3-trifluoropropene crude product tank is externally connected with a 2-chloro-3, 3, 3-trifluoropropene input valve pipeline at the top of the 2-chloro-3, 3, 3-trifluoropropene crude product tank, a feed pump at the bottom of the 2-chloro-3, 3, 3-trifluoropropene crude product tank is communicated with a feed port at the middle upper part of the 2-chloro-3, a pipeline between the crude product material-pumping pump of the 2-chloro-3, 3, 3-trifluoropropene and the 2-chloro-3, 3, 3-trifluoropropene alkali washing tower is communicated with a feed inlet of the static mixer through a valve, a valve pipeline is connected outside a discharge port at the top of the 2-chloro-3, 3, 3-trifluoropropene alkali washing tower, and waste alkali liquor is continuously output.
According to the invention, preferably, the hydrogen fluoride vaporizer, the liquid chlorine vaporizer and the tetrachloropropane preheater are all provided with jackets, and steam is introduced into the jackets for heating.
According to the invention, preferably, the premixer adopts a falling film evaporation premixer to promote the liquid material to be quickly and fully vaporized and enhance the mixing effect of all gas phase materials, the outside of the falling film evaporation premixer is provided with a jacket, and heat conducting oil is introduced into the jacket for heating.
According to the invention, preferably, the reactor is a fixed bed tubular reactor; preferably, the lower end enclosure of the fixed bed tubular reactor is provided with a jacket, and heat conducting oil is introduced into the jacket for heating, so that the feeding temperature is further increased to the reaction temperature.
According to the invention, the rectification pre-separation system adopts a separation mode of three continuous rectification towers of a rectification tower I, a rectification tower II and a rectification tower III to realize the high-efficiency separation of reaction by-product hydrogen chloride, high-boiling-point substances and excessive hydrogen fluoride.
According to the invention, preferably, the condenser of the rectifying tower II is cooled by adopting frozen brine at the temperature of-15 ℃ to-35 ℃, so that the cooling effect of other materials except hydrogen chloride is enhanced, and further preferably, the temperature of the frozen brine is-30 ℃ to-35 ℃.
According to the invention, the phase separation condenser is preferably cooled by using frozen brine at-15 ℃ to-35 ℃, and the temperature of the frozen brine is further preferably-30 ℃ to-35 ℃.
According to the invention, the phase separator is preferably provided with a jacket, and the phase separator is cooled by introducing frozen brine, wherein the temperature of the frozen brine is-15 ℃ to-35 ℃, and the temperature of the frozen brine is further preferably-30 ℃ to-35 ℃.
According to the invention, preferably, the middle upper part of the 3,3, 3-trifluoropropene alkali wash tower is connected with an alkali liquor input pipeline, and the middle lower part of the 2-chloro-3, 3, 3-trifluoropropene alkali wash tower is connected with an alkali liquor input pipeline.
According to the invention, the method for co-producing 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene by using the device comprises the following steps:
(1) reaction process
a) Pumping hydrogen fluoride to a hydrogen fluoride vaporizer for preheating by a hydrogen fluoride metering tank, b) pumping liquid chlorine to the liquid chlorine vaporizer for vaporization by a liquid chlorine metering tank, c) pumping 1,1,1, 3-tetrachloropropane to a tetrachloropropane preheater for preheating by a tetrachloropropane metering tank, and simultaneously and continuously introducing the preheated materials in the steps a), b) and c) into a falling film evaporation premixer; the hydrogen fluoride gas is excessively introduced, so that the vaporization partial pressure of the 1,1,1, 3-tetrachloropropane is effectively reduced, the 1,1,1, 3-tetrachloropropane is rapidly vaporized in the premixer, the premixer adopts a falling film evaporation premixer, and the continuous rapid vaporization and the full mixing of the mixed materials in the premixer are promoted; continuously introducing the vaporized and mixed materials into a fixed bed tubular reactor filled with a catalyst for reaction; after the reaction is finished, continuously discharging the mixed material from a discharge hole of the reactor, cooling the mixed material by a reaction cooler, and then feeding the cooled mixed material into a rectification pre-separation system;
(2) pre-separation by rectification
Continuously feeding the cooled mixed material from a middle feeding hole of a rectifying tower I, rectifying at positive pressure, condensing the tower top material by circulating water at 5-10 ℃ in a rectifying tower I condenser, refluxing, extracting a mixture of hydrogen fluoride, chlorine, 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene, continuously introducing the mixture into a middle liquid phase feeding hole of a rectifying tower II, continuously introducing uncondensed components of the rectifying tower I condenser, which are mainly hydrogen chloride and a small amount of chlorine, into a middle gas phase feeding hole of the rectifying tower II, continuously discharging high-boiling-point substances at the bottom of the rectifying tower I, taking the high-boiling-point substances as waste liquid, and transferring and burning the waste liquid; continuous positive pressure rectification is carried out in a rectification II tower, materials at the top of the tower flow back after being condensed by frozen saline water at the temperature of minus 30 ℃ to minus 35 ℃ in a rectification II tower condenser, and hydrogen chloride and a small amount of chlorine are extracted and enter a hydrogen chloride absorption device; continuously discharging a mixture of hydrogen fluoride, 3,3, 3-trifluoropropene, 2-chloro-3, 3, 3-trifluoropropene and the like from the bottom of a rectification II tower, continuously inputting the mixture into a rectification III tower, rectifying at positive pressure, condensing the materials at the top of the tower by circulating water at 5-10 ℃ in a condenser of the rectification III tower, refluxing, extracting an azeotrope-like mixture, entering an azeotrope-like extraction separation system, continuously discharging hydrogen fluoride from the bottom of the rectification III tower, and pumping the hydrogen fluoride to a hydrogen fluoride vaporizer for use by a hydrogen fluoride recovery pump;
(3) azeotrope-like extraction separation
Introducing an azeotrope-like mixture extracted from the top of a rectifying tower III into a static mixer, pumping a certain amount of 2-chloro-3, 3, 3-trifluoropropene into the static mixer from a crude product tank of the 2-chloro-3, 3, 3-trifluoropropene, fully mixing the 2-chloro-3, 3, 3-trifluoropropene as an extractant with the azeotrope-like mixture, cooling by a phase separation condenser with frozen brine at-30 to-35 ℃, then entering a phase separator for standing and phase separation, introducing the frozen brine at-30 to-35 ℃ into a jacket of the phase separator for cooling and maintaining a certain positive pressure, discharging a light component phase from the upper part of the phase separator after the phase separation is completed, entering a light phase tank, pumping the light phase into a rectifying tower III by a light phase material-pumping pump for applying, wherein the recombination phase separation comprises the 3,3, 3-trifluoropropene and the 2-chloro-3, 3, 3-trifluoropropene and a small amount of hydrogen fluoride are discharged from the bottom of a phase separator, and are pumped to a rectification IV tower through a heavy phase material pump, the rectification IV tower is subjected to positive pressure rectification, the materials at the tower top are condensed by circulating water at the temperature of 5-10 ℃ in a rectification IV tower condenser and then flow back, the extracted azeotrope-like mixture is introduced into a static mixer for application, the mixture of 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene discharged from the tower bottom of the rectification IV tower enters a rectification V tower, the mixture is subjected to positive pressure rectification, the materials at the tower top are condensed by the circulating water at the temperature of 5-10 ℃ in a rectification V tower condenser and then flow back, the extracted 3,3, 3-trifluoropropene crude product is continuously introduced into a 3, 3-trifluoropropene alkali washing tower for alkali washing, the 2-chloro-3, 3, 3-trifluoropropene crude product is continuously output from the tower bottom of the rectification V tower, the 2-chloro-, 3, 3-trifluoropropene crude product tank;
feeding a 3,3, 3-trifluoropropene crude product from a feed inlet at the middle lower part of a 3,3, 3-trifluoropropene alkali wash tower, feeding alkali liquor from a feed inlet at the middle upper part of the 3,3, 3-trifluoropropene alkali wash tower, wherein positive pressure exists in the alkali wash tower, 3,3, 3-trifluoropropene is fully alkali washed, discharging from a discharge outlet at the top of the 3,3, 3-trifluoropropene alkali wash tower, feeding the discharged material into a 3,3, 3-trifluoropropene crude product tank, further rectifying and purifying to obtain a 3,3, 3-trifluoropropene product, and continuously discharging waste alkali liquor from the bottom of the 3,3, 3-trifluoropropene alkali wash tower for transfer treatment; pumping part of the 2-chloro-3, 3, 3-trifluoropropene crude product in the 2-chloro-3, 3, 3-trifluoropropene crude product tank to a static mixer for mixing and extracting, and washing the other part with alkali; feeding 2-chloro-3, 3, 3-trifluoropropene from a feed inlet at the middle upper part of a 2-chloro-3, 3, 3-trifluoropropene alkali wash tower, feeding alkali liquor from a feed inlet at the middle lower part of the 2-chloro-3, 3, 3-trifluoropropene alkali wash tower, and feeding positive pressure in the alkali wash tower to fully alkali wash the 2-chloro-3, 3, 3-trifluoropropene from a discharge outlet at the bottom of the 2-chloro-3, 3, 3-trifluoropropene alkali wash tower, further rectifying and purifying to obtain a 2-chloro-3, 3, 3-trifluoropropene product, and continuously discharging waste alkali liquor from the top of the 2-chloro-3, 3, 3-trifluoropropene alkali wash tower for transfer treatment.
According to the invention, preferably, the temperature in the falling film evaporation premixer in the step (1) is 240-300 ℃, and the working pressure is 1.0-1.3 MPa;
preferably, the molar ratio of the chlorine gas to the 1,1,1, 3-tetrachloropropane is (1-5): 100, the chlorine gas inhibits the decomposition of the raw material 1,1,1, 3-tetrachloropropane, inhibits the carbon deposition of the fluorination catalyst, prolongs the service life of the catalyst, and the output ratio of the product 2-chloro-3, 3, 3-trifluoropropene can be regulated and controlled by regulating the introduction amount of liquid chlorine;
preferably, the molar ratio of the hydrogen fluoride to the 1,1,1, 3-tetrachloropropane is (10-50): 1, the hydrogen fluoride is excessive, the partial pressure of vaporization of the 1,1,1, 3-tetrachloropropane is reduced, the 1,1,1, 3-tetrachloropropane is ensured to be rapidly vaporized, and the hydrogen fluoride and the chlorine are fully mixed;
preferably, the reaction temperature is 240-300 ℃, and the reaction pressure is 1.0-1.3 MPa.
According to the invention, preferably, the working pressure of the rectification I tower and the rectification II tower in the step (2) is 1.0-1.2MPa, and the working pressure of the rectification III tower is 0.8-1.0 MPa.
According to the invention, the azeotrope-like mixture described in step (2) comprises hydrogen fluoride, 3,3, 3-trifluoropropene, 2-chloro-3, 3, 3-trifluoropropene.
According to the invention, preferably, the working pressure of the phase separator in the step (3) is 0.6-0.8MPa, the working pressure of the rectification IV tower is 0.6-1.0MPa, the working pressure of the rectification V tower is 0.5-0.8MPa, the working pressure of the 3,3, 3-trifluoropropene alkali washing tower is 0.6-0.8MPa, and the working pressure of the 2-chloro-3, 3, 3-trifluoropropene alkali washing tower is 0.4-0.6 MPa; the alkali liquor is 5-15 wt% potassium hydroxide aqueous solution.
The invention has not been described in detail, but is processed according to the conventional technology in the field.
The invention has the beneficial effects that:
1. the premixer of the invention adopts a falling film evaporation premixer to promote the rapid and sufficient vaporization of the liquid material 1,1,1, 3-tetrachloropropane and enhance the mixing effect of various gas-phase materials.
2. The rectification pre-separation system adopts a three-tower continuous rectification mode to realize the high-efficiency separation of reaction by-product hydrogen chloride, high-boiling-point substances and excessive hydrogen fluoride.
3. The invention utilizes the principle that liquid 2-chloro-3, 3, 3-trifluoropropene is mutually soluble with liquid 3,3, 3-trifluoropropene and is not soluble with liquid hydrogen fluoride, adopts 2-chloro-3, 3, 3-trifluoropropene which is one of reaction products as an extracting agent, dissolves 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene in an azeotrope-like mixture, and realizes the liquid-liquid two-phase extraction separation of the azeotrope-like mixture.
4. The production method provided by the invention is realized by the production device with the specific structure and the connection relation, has the advantages of mild reaction conditions, high reaction rate, good atom economy, stable product quality, adjustable product proportion and the like, can realize automatic control of the whole flow, saves labor, and is suitable for industrial co-production of 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene.
Drawings
FIG. 1 is a schematic diagram of a co-production apparatus of 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene according to the present invention.
Wherein: 1. hydrogen fluoride metering tank, 2, liquid chlorine metering tank, 3, tetrachloropropane metering tank, 4, hydrogen fluoride metering pump, 5, liquid chlorine metering pump, 6, tetrachloropropane metering pump, 7, hydrogen fluoride vaporizer, 8, liquid chlorine vaporizer, 9, tetrachloropropane preheater, 10, premixer, 11, reactor, 12, reaction cooler, 13, rectification column I, 14, rectification column I condenser, 15, rectification column II, 16, rectification column II condenser, 17, rectification column III, 18, rectification column III condenser, 19, hydrogen fluoride recovery pump, 20, static mixer, 21, phase separation condenser, 22, phase separator, 23, light phase tank, 24, light phase feed pump, 25, heavy phase feed pump, 26, rectification column IV, 27, rectification column IV condenser, 28, bottom rectification column V, 29, rectification column V condenser, 30, cooler, 31, 2-chloro-3, 3, 3-trifluoropropene crude product tank, 32, 2-chloro-3, 3, 3-trifluoropropene crude product feeding pump, 33, 3,3, 3-trifluoropropene caustic wash tower, 34, 3,3, 3-trifluoropropene crude product tank and 35, 2-chloro-3, 3, 3-trifluoropropene caustic wash tower.
Detailed Description
For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.
Example 1:
a co-production device of 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene comprises a reaction system, a rectification pre-separation system and an azeotrope-like extraction separation system;
the reaction system comprises a hydrogen fluoride metering tank 1, a liquid chlorine metering tank 2, a tetrachloropropane metering tank 3, a hydrogen fluoride metering pump 4, a liquid chlorine metering pump 5, a tetrachloropropane metering pump 6, a hydrogen fluoride vaporizer 7, a liquid chlorine vaporizer 8, a tetrachloropropane preheater 9, a premixer 10, a reactor 11 and a reaction cooler 12, wherein the hydrogen fluoride metering tank 1 is communicated with a bottom feed inlet of the hydrogen fluoride vaporizer 7 through the hydrogen fluoride metering pump 4, a top discharge outlet of the hydrogen fluoride vaporizer 7 is communicated with a top gas phase feed inlet of the premixer 10, the liquid chlorine metering tank 2 is communicated with a bottom feed inlet of the liquid chlorine vaporizer 8 through the liquid chlorine metering pump 5, a top discharge outlet of the liquid chlorine vaporizer 8 is communicated with a top gas phase feed inlet of the premixer 10, the tetrachloropropane metering tank 3 is communicated with a bottom feed inlet of the tetrachloropropane preheater 9 through the tetrachloropropane metering pump 6, a top discharge outlet of the tetrachloropropane preheater 9 is communicated with a side top liquid feed inlet of the, a discharge port at the bottom of the premixer 10 is communicated with a feed port at the side bottom of the reactor 11, and a discharge port at the top of the reactor 11 is communicated with a feed port in the middle of the rectifying tower I13 through a reaction cooler 12;
the rectification pre-separation system comprises a rectification I tower 13, a rectification I tower condenser 14, a rectification II tower 15, a rectification II tower condenser 16, a rectification III tower 17, a rectification III tower condenser 18 and a hydrogen fluoride recovery pump 19, wherein a gas phase discharge port at the top of the rectification I tower 13 is communicated with a feed inlet of the rectification I tower condenser 14, a valve pipeline is connected outside a discharge port at the bottom of the rectification I tower 13 for continuously outputting waste liquid, a gas phase discharge port of the rectification I tower condenser 14 is communicated with a gas phase feed inlet at the middle part of the rectification II tower 15, a liquid phase discharge port of the rectification I tower condenser 14 is communicated with a liquid phase return port at the side top of the rectification I tower 13, a liquid phase feed inlet at the middle part of the rectification II tower 15 is communicated with a pipeline between the liquid phase discharge port of the rectification I tower condenser 14 and the liquid phase return port at the side of the rectification I tower 13, a gas phase discharge port at the top of the rectification II, a liquid phase discharge port of a condenser 16 of a rectification II tower is communicated with a liquid phase return port at the top of the side of the rectification II tower 15, a discharge port at the bottom of the rectification II tower 15 is communicated with a feed port at the middle part of a rectification III tower 17, a gas phase discharge port at the top of the rectification III tower 17 is communicated with a feed port of a condenser 18 of the rectification III tower, a liquid phase discharge port of the condenser 18 of the rectification III tower is communicated with a liquid phase return port at the top of the side of the rectification III tower 17, a discharge port at the bottom of the rectification III tower 17 is communicated with a feed port of a hydrogen fluoride vaporizer 7 through a hydrogen fluoride recovery pump 19, and a pipeline between the liquid phase discharge port of the;
the azeotrope-like extraction separation system comprises a static mixer 20, a phase separation condenser 21, a phase separator 22, a light phase tank 23, a light phase material pumping pump 24, a heavy phase material pumping pump 25, a rectification IV tower 26, a rectification IV tower condenser 27, a rectification V tower 28, a rectification V tower condenser 29, a tower bottom cooler 30, a 2-chloro-3, 3, 3-trifluoropropene crude product tank 31, a 2-chloro-3, 3, 3-trifluoropropene crude product material pumping pump 32, a 3,3, 3-trifluoropropene alkali washing tower 33, a 3,3, 3-trifluoropropene crude product tank 34 and a 2-chloro-3, 3, 3-trifluoropropene alkali washing tower 35, wherein a material outlet of the static mixer 20 is communicated with a material inlet of the phase separator middle part 22 through the phase separation condenser 21, a material outlet of the light phase at the top of the phase separator 22 is communicated with a material inlet of the light phase tank 23, a discharge port of a light phase tank 23 is communicated with a middle feed port of a rectifying III tower 17 through a light phase material-pumping pump 24, a discharge port at the bottom of a phase separator 22 is communicated with a middle feed port of a rectifying IV tower 26 through a heavy phase material-pumping pump 25, a gas phase discharge port at the top of the rectifying IV tower 26 is communicated with a feed port of a rectifying IV tower condenser 27, a liquid phase discharge port of the rectifying IV tower condenser 27 is communicated with a top liquid phase return port at the side of the rectifying IV tower 26, a pipeline between the liquid phase discharge port of the rectifying IV tower condenser 27 and the top liquid phase return port at the side of the rectifying IV tower 26 is communicated with a feed port of a static mixer 20, a discharge port at the bottom of the rectifying IV tower 26 is communicated with a middle feed port of a rectifying V tower 28, a gas phase discharge port at the top of the rectifying V tower 28 is communicated with a feed port of a V tower condenser 29, a pipeline between the liquid phase discharge port of the rectifying V tower, a feed inlet at the middle lower part of a 3, 3-trifluoropropene caustic wash tower 33 is communicated, a discharge outlet at the top of the 3,3, 3-trifluoropropene caustic wash tower 33 is communicated with a feed inlet at the top of a 3,3, 3-trifluoropropene crude tank 34, a valve pipeline is connected outside the discharge outlet at the bottom of the 3,3, 3-trifluoropropene caustic wash tower 33 for continuously outputting waste alkali liquor, a discharge outlet at the bottom of a rectification V-tower 28 is communicated with a feed inlet at the side of a 2-chloro-3, 3, 3-trifluoropropene crude tank 31 through a tower bottom cooler 30, a 2-chloro-3, 3, 3-trifluoropropene crude tank 31 is externally connected with a 2-chloro-3, 3, 3-trifluoropropene input valve pipeline, a 2-chloro-3, 3,3, 3-trifluoropropene crude tank 31 is externally connected with a discharge outlet at the bottom of the 2-chloro-3, 3, 3-trifluoropropene crude tank 31, the feed inlet at the middle upper part of the 3, 3-trifluoropropene alkaline washing tower 35 is communicated, a pipeline between the crude product material-pumping pump 32 of the 2-chloro-3, 3, 3-trifluoropropene and the 2-chloro-3, 3, 3-trifluoropropene alkaline washing tower 35 is communicated with the feed inlet of the static mixer 20 through a valve, a valve pipeline is connected outside the discharge outlet at the top part of the 2-chloro-3, 3, 3-trifluoropropene alkaline washing tower 35, and waste alkaline liquor is continuously output.
In the embodiment, the hydrogen fluoride vaporizer 7, the liquid chlorine vaporizer 8 and the tetrachloropropane preheater 9 are all provided with jackets, and steam is introduced into the jackets for heating; the premixer 10 adopts a falling film evaporation premixer 10 to promote the liquid material to be quickly and fully vaporized and strengthen the mixing effect of various gas phase materials, a jacket is arranged outside the falling film evaporation premixer 10, and heat conducting oil is introduced into the jacket for heating; the reactor 11 is a fixed bed tubular reactor 11, the condenser 16 of the rectifying II tower is cooled by freezing saline water at a temperature of between 15 ℃ below zero and 30 ℃ below zero, the cooling effect of other materials except hydrogen chloride is enhanced, the jacket of the phase separation condenser 21 is cooled by freezing saline water at a temperature of between 15 ℃ below zero and 35 ℃ below zero, the phase separator 22 is provided with a jacket, the freezing saline water is introduced for cooling, and the temperature of the freezing saline water is between 15 ℃ below zero and 35 ℃ below zero.
Example 2
A co-production plant of 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene as described in example 1, except that: the lower end socket of the fixed bed tubular reactor 11 is provided with a jacket, heat conducting oil is introduced into the jacket for heating, the feeding temperature is further increased to the reaction temperature, the condenser 16 of the rectification II tower is cooled by frozen brine at-30 ℃ to-35 ℃, the cooling effect of other materials except hydrogen chloride is further enhanced, the material loss is reduced, the yield is improved, the jacket of the phase separation condenser 21 is cooled by the frozen brine at-30 ℃ to-35 ℃, the jacket of the phase separator 20 is cooled by the frozen brine at-30 ℃ to-35 ℃, the middle upper part of the 3,3, 3-trifluoropropene alkali washing tower 33 is connected with an alkali liquor input pipeline, and the middle lower part of the 2-chloro-3, 3, 3-trifluoropropene alkali washing tower 35 is connected with an alkali liquor input pipeline.
Example 3
A method for co-producing 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene using the production apparatus described in example 1 or 2, wherein the fluorination catalyst used in the example is a chromium-based fluorination catalyst, comprising the steps of:
(1) reaction process
a) Pumping hydrogen fluoride to a hydrogen fluoride vaporizer 7 by a hydrogen fluoride metering tank 1 for preheating, b) pumping liquid chlorine to a liquid chlorine vaporizer 8 by a liquid chlorine metering tank 2 for preheating, c) pumping 1,1,1, 3-tetrachloropropane to a tetrachloropropane preheater 9 by a tetrachloropropane metering tank 3 for preheating, simultaneously and continuously introducing the materials preheated in the steps a), b) and c) into a falling film evaporation premixer 10, wherein the temperature in the falling film evaporation premixer 10 is 240-300 ℃, the working pressure is 1.0-1.3MPa, wherein the mol ratio of chlorine to 1,1,1, 3-tetrachloropropane is (1-5): 100, chlorine inhibits the decomposition of the raw material 1,1,1, 3-tetrachloropropane, inhibits the carbon deposition of the fluorination catalyst, prolongs the service life of the catalyst, and adjusts the chlorine input, the output proportion of the product 2-chloro-3, 3, 3-trifluoropropene can be regulated and controlled; the molar ratio of hydrogen fluoride to 1,1,1, 3-tetrachloropropane is (10-50): 1, hydrogen fluoride gas is excessively introduced, the partial pressure of vaporization of 1,1,1, 3-tetrachloropropane is effectively reduced, 1,1, 3-tetrachloropropane is rapidly vaporized in the premixer, the premixer adopts the falling film evaporation premixer 10, and continuous rapid vaporization and full mixing in the mixed material premixer are realized. The vaporized and mixed materials are continuously introduced into a fixed bed tubular reactor 11 filled with a catalyst for reaction, the reaction temperature is 240-300 ℃, the reaction pressure is 1.0-1.3MPa, chlorine is added in the reaction process to generate 2-chloro-3, 3, 3-trifluoropropene, and after the reaction is finished, the mixed materials are continuously discharged from a discharge port of the fixed bed tubular reactor 11, cooled by a reaction cooler 12 and then enter a rectification pre-separation system.
(2) Pre-separation by rectification
And continuously feeding the cooled mixed material from a middle feeding hole of a rectifying tower I13, rectifying under positive pressure at the pressure of 1.0-1.2MPa, condensing the tower top material through circulating water at 145-10 ℃ in a rectifying tower I condenser, refluxing, extracting hydrogen fluoride, chlorine, 3,3, 3-trifluoropropene and a 2-chloro-3, 3, 3-trifluoropropene mixture, continuously introducing the hydrogen fluoride, chlorine, the 3, 3-trifluoropropene and the 2-chloro-3, 3, 3-trifluoropropene mixture into a middle liquid phase feeding hole of a rectifying tower II 15, continuously introducing uncondensed components of a rectifying tower I condenser 14, mainly hydrogen chloride and a small amount of chlorine into a middle gas phase feeding hole of the rectifying tower II 15, continuously discharging high-boiling substances at the bottom of the rectifying tower I13. And (3) continuously carrying out positive pressure rectification on the rectification II tower 15 under the pressure of 1.0-1.2MPa, condensing the materials at the top of the tower by using frozen saline water at the temperature of 16-30-35 ℃ in a rectification II tower condenser, refluxing, and extracting hydrogen chloride and a small amount of chlorine to enter a hydrogen chloride absorption device. And continuously discharging the mixture of hydrogen fluoride, 3,3, 3-trifluoropropene, 2-chloro-3, 3, 3-trifluoropropene and the like from the bottom of a rectification II tower 15, continuously inputting the mixture into a rectification III tower 17, rectifying under positive pressure at the pressure of 0.8-1.0MPa, condensing the tower top material by circulating water at 185-10 ℃ in a rectification III tower condenser, refluxing, collecting azeotrope-like mixture hydrogen fluoride, 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene, and feeding the mixture into an azeotrope-like extraction separation system, continuously discharging the hydrogen fluoride from the bottom of the rectification III tower 17, and pumping the hydrogen fluoride back to a hydrogen fluoride vaporizer 7 for use by a hydrogen fluoride recovery pump 19.
(3) Azeotrope-like extraction separation
Introducing an azeotrope-like mixture extracted from the tower top of the rectifying tower III 17 into a static mixer 20, pumping a certain amount of 2-chloro-3, 3, 3-trifluoropropene from a crude 2-chloro-3, 3, 3-trifluoropropene tank 31 into the static mixer 20, 2-chloro-3, 3, 3-trifluoropropene as an extractant to be fully mixed with the azeotrope-like mixture, cooling by a frozen brine at the temperature of between 21 and 30 ℃ below zero and 35 ℃ below zero in a phase separation condenser, allowing the mixture to enter a phase separator 22 for standing and phase separation, allowing the phase separator 22 to jacket to introduce the frozen brine at the temperature of between 30 ℃ below zero and 35 ℃ below zero to cool and maintain the pressure at 0.6 to 0.8MPa, discharging a light component phase from the upper part of the phase separator 22 after phase separation, allowing the light component phase to enter a light phase tank 23, pumping the light phase to the rectifying tower III 17 by a light phase pumping pump 24, and performing recombination, 3-trifluoropropene, 2-chloro-3, 3, 3-trifluoropropene and a small amount of hydrogen fluoride are discharged from the bottom of a phase separator 22, pumped to a rectification IV tower 26 by a heavy phase material pump 25, rectified at positive pressure with the pressure of 0.6-1.0MPa, materials at the tower top are condensed by circulating water at 275-10 ℃ in a rectification IV tower condenser and then refluxed, an extracted azeotrope-like mixture is led into a static mixer 20 for use, a mixture of 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene discharged from the tower bottom of the rectification IV tower 26 is led into a rectification V tower 28, rectified at positive pressure with the pressure of 0.5-0.8MPa, materials at the tower top are condensed by circulating water at 295-10 ℃ in a rectification V tower condenser and then refluxed, crude products of 3,3, 3-trifluoropropene are continuously led into a 3,3, 3-trifluoropropene alkaline washing tower 33 for alkaline washing, and 2-chloro-3 is continuously output from the rectification V tower 28, and cooling the 3, 3-trifluoropropene crude product by circulating water at 305-10 ℃ through a tower bottom cooler, and then feeding the cooled crude product into a 2-chloro-3, 3, 3-trifluoropropene crude product tank 31.
Feeding a 3,3, 3-trifluoropropene crude product from a feed inlet at the middle lower part of a 3,3, 3-trifluoropropene alkali washing tower 33, feeding a 5 wt% -15 wt% potassium hydroxide aqueous solution from a feed inlet at the middle upper part of the 3,3, 3-trifluoropropene alkali washing tower 33, fully alkali washing the 3,3, 3-trifluoropropene alkali washing tower 33 at the working pressure of 0.6-0.8MPa, discharging the 3,3, 3-trifluoropropene from a discharge outlet at the top of the 3,3, 3-trifluoropropene alkali washing tower 33, feeding the discharged material into a 3,3, 3-trifluoropropene crude product tank 34, further rectifying and purifying to obtain a 3,3, 3-trifluoropropene product, and continuously discharging waste alkali liquor from the bottom of the 3,3, 3-trifluoropropene alkali washing tower 33 for transfer treatment. One part of the 2-chloro-3, 3, 3-trifluoropropene crude product in the 2-chloro-3, 3, 3-trifluoropropene crude product tank 31 is pumped to a static mixer 20 for mixing and extraction, and the other part is subjected to alkali washing treatment. Feeding 2-chloro-3, 3, 3-trifluoropropene from a feed inlet at the middle upper part of a 2-chloro-3, 3, 3-trifluoropropene alkali wash tower 35, feeding 5 wt% -15 wt% of potassium hydroxide aqueous solution from a feed inlet at the middle lower part of the 2-chloro-3, 3, 3-trifluoropropene alkali wash tower 35, discharging 2-chloro-3, 3, 3-trifluoropropene from a discharge outlet at the bottom of the 2-chloro-3, 3, 3-trifluoropropene alkali wash tower 35 after fully alkali washing at the working pressure of 0.4-0.6MPa, further rectifying and purifying to obtain 2-chloro-3, 3, 3-trifluoropropene products, continuously discharging waste alkali liquor from the top of the 2-chloro-3, 3, 3-trifluoropropene alkali wash tower 35, and (5) transferring.
Comparative example 1
As described in example 1, except that:
the reaction premixer 10 adopts a traditional mixer, the reactor 11 adopts a traditional stirring reaction kettle, and the batch reaction is carried out. The rectification pre-separation adopts a common batch type rectification tower for rectification separation. The method is characterized in that equipment such as a static mixer 20, a phase separation condenser 21, a phase separator 22, a light phase tank 23, a light phase material pumping pump 24, a heavy phase material pumping pump 25 and the like is not used, materials extracted from the top of a rectifying column III directly enter a rectifying column IV, and the liquid-liquid two-phase extraction separation of azeotrope-like substances is realized without adopting the means of 2-chloro-3, 3, 3-trifluoropropene extraction and phase separation.
Test examples
The respective yields and the total yield of 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene, respectively, were calculated according to the method of example 3 using the production apparatuses of example 1 and comparative example 1, based on 1,1,1, 3-tetrachloropropane, and the results are shown in table 1.
TABLE 1
Number/item Yield of 3,3, 3-trifluoropropene% Yield of 2-chloro-3, 3, 3-trifluoropropene% The total yield of the product is%
Example 1 92.5 4.5 97
Comparative example 1 87.5 0 87.5
As can be seen from Table 1, the co-production method of 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene of the present invention realizes the co-production of 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene, and simultaneously, the yield of 3,3, 3-trifluoropropene is also significantly improved, the total yield is improved from 87.5% to 97%, the atom economy is good, the benefit is improved, the waste generation is reduced, and the present invention is more favorable for environmental protection.
The above description is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (17)

1. A co-production method of 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene comprises the following steps:
(1) reaction process
Preheating hydrogen fluoride, liquid chlorine and tetrachloropropane, then vaporizing and mixing, and reacting the vaporized and mixed materials under the action of a fluorination catalyst, wherein the reaction temperature is 240-300 ℃, and the reaction pressure is 1.0-1.3 MPa; after the reaction is finished, cooling the mixed material, and then performing rectification pre-separation;
the vaporization mixing process is carried out in a falling film evaporation premixer;
(2) pre-separation by rectification
The cooled mixed material is subjected to multistage rectification, an azeotrope-like mixture is obtained at the top of the rectification tower, and three-stage rectification of a first rectification tower, a second rectification tower and a third rectification tower is adopted and connected in series;
(3) azeotrope-like extraction separation
Adding 2-chloro-3, 3, 3-trifluoropropene serving as an extracting agent into the azeotrope-like mixture, fully mixing the mixture with the azeotrope-like mixture, cooling, standing for phase separation, and performing multi-stage rectification on the recombined phase separation after phase separation;
the full mixing process of the extractant and the azeotrope-like mixture is carried out in a static mixer, the recombination split phase comprises 3,3, 3-trifluoropropene, 2-chloro-3, 3, 3-trifluoropropene and a small amount of hydrogen fluoride, and the two-stage rectification of the extractant and the azeotrope-like mixture is carried out in series by a fourth rectifying tower and a fifth rectifying tower;
condensing the materials at the top of the rectifying tower, and then performing alkali washing to obtain a crude product of the 3,3, 3-trifluoropropene;
condensing and then performing alkali washing on the materials at the bottom of the rectifying tower to obtain a crude product of the 2-chloro-3, 3, 3-trifluoropropene.
2. The process for co-producing 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene according to claim 1, wherein the temperature of the vaporization mixing in step (1) is 240 to 300 ℃ and the pressure of the vaporization mixing is 1.0 to 1.3 MPa.
3. The process for co-producing 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene according to claim 1, wherein the molar ratio of chlorine gas to 1,1,1, 3-tetrachloropropane in step (1) is (1-5): 100, and the molar ratio of hydrogen fluoride to 1,1,1, 3-tetrachloropropane is (10-50): 1.
4. The process for co-producing 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene according to claim 1, wherein the fluorination catalyst in the step (1) is a chromium-based fluorination catalyst.
5. The process for co-producing 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene according to claim 1, wherein the reaction process in step (1) is carried out in a fixed-bed tubular reactor.
6. The co-production method of 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene according to claim 1, wherein in step (2), the first distillation column adopts positive pressure distillation, the pressure is 1.0-1.2MPa, the material at the top of the first distillation column is condensed by circulating water at 5-10 ℃ and then flows back, the mixture of hydrogen fluoride, chlorine, 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene is extracted and continuously enters the middle liquid phase of the second distillation column for feeding, the uncondensed components of the material at the top of the first distillation column mainly comprise hydrogen chloride and a small amount of chlorine, the material continuously enters the middle gas phase of the second distillation column for feeding, and the high-boiling substances are continuously discharged from the bottom of the first distillation column for treating as waste liquid;
the second rectifying tower is used for continuous positive pressure rectification, the pressure is 1.0-1.2MPa, materials at the top of the second rectifying tower are condensed at minus 30 ℃ to minus 35 ℃ and then flow back, hydrogen chloride and a small amount of chlorine are extracted, and the hydrogen chloride and the small amount of chlorine enter a hydrogen chloride absorption device; continuously discharging a mixture of hydrogen fluoride, 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene from the bottom of the second rectifying tower and continuously inputting the mixture into the third rectifying tower;
and (3) continuously carrying out positive pressure rectification in a third rectifying tower at the pressure of 0.8-1.0MPa, condensing the materials at the top of the third rectifying tower by circulating water at the temperature of 5-10 ℃, refluxing, extracting azeotrope-like hydrogen fluoride, 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene, continuously discharging hydrogen fluoride at the bottom of the third rectifying tower, and returning to the step (1) for reuse.
7. The co-production method of 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene according to claim 1, wherein the cooling temperature after the sufficient mixing in step (3) is-30 ℃ to-35 ℃, the temperature during the standing phase separation process is-30 ℃ to-35 ℃, and the pressure is 0.6MPa to 0.8 MPa.
8. The process for co-producing 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene according to claim 1, wherein the light component phase after the standing phase separation in step (3) is returned to the third distillation column in step (2) for reuse;
the fourth rectifying tower adopts positive pressure rectification, the pressure is 0.6-1.0MPa, materials at the top of the fourth rectifying tower flow back after being condensed by circulating water at the temperature of 5-10 ℃, an azeotrope-like mixture is extracted and returned to an extracting agent to be mixed with the azeotrope-like mixture for use, and a mixture of 3,3, 3-trifluoropropene, 2-chloro-3, 3, 3-trifluoropropene is discharged from the bottom of the fourth rectifying tower and enters a fifth rectifying tower;
the fifth rectifying tower adopts positive pressure rectification, the pressure is 0.5-0.8MPa, materials at the top of the fifth rectifying tower are condensed by circulating water at the temperature of 5-10 ℃ and then flow back, a 3,3, 3-trifluoropropene crude product is extracted, the 3,3, 3-trifluoropropene crude product is obtained after alkali washing, and the 3,3, 3-trifluoropropene product is obtained through further rectification and purification; and continuously outputting a 2-chloro-3, 3, 3-trifluoropropene crude product from the bottom of the fifth rectifying tower, cooling by circulating water at 5-10 ℃, returning one part of the crude product to the extraction agent for mixing with the azeotrope-like mixture, washing the other part of the crude product by alkali to obtain the 2-chloro-3, 3, 3-trifluoropropene crude product, and further rectifying and purifying to obtain the 2-chloro-3, 3, 3-trifluoropropene product.
9. A co-production device of 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene is characterized by comprising a reaction system, a rectification pre-separation system and an azeotrope-like extraction separation system;
the reaction system comprises a hydrogen fluoride metering tank, a liquid chlorine metering tank, a tetrachloropropane metering tank, a hydrogen fluoride metering pump, a liquid chlorine metering pump, a tetrachloropropane metering pump, a hydrogen fluoride vaporizer, a liquid chlorine vaporizer, a tetrachloropropane preheater, a premixer, a reactor and a reaction cooler, wherein the hydrogen fluoride metering tank is communicated with a bottom feed inlet of the hydrogen fluoride vaporizer through the hydrogen fluoride metering pump, a top discharge outlet of the hydrogen fluoride vaporizer is communicated with a top gas phase feed inlet of the premixer, the liquid chlorine metering tank is communicated with a bottom feed inlet of the liquid chlorine vaporizer through the liquid chlorine metering pump, a top discharge outlet of the liquid chlorine vaporizer is communicated with a top gas phase feed inlet of the premixer, the tetrachloropropane metering tank is communicated with a bottom feed inlet of the tetrachloropropane preheater through the tetrachloropropane metering pump, a top discharge outlet of the tetrachloropropane preheater is communicated with a side top liquid feed inlet of the premixer, a bottom discharge outlet of the premixer is communicated, a discharge hole at the top of the reactor is communicated with a feed hole in the middle of the rectifying tower I through a reaction cooler; the premixer adopts a falling film evaporation premixer;
the rectification pre-separation system comprises rectification
Figure DEST_PATH_IMAGE002
Column, rectifying I column condenser and rectifying
Figure DEST_PATH_IMAGE004
Column, rectifying II column condenser and rectifying
Figure DEST_PATH_IMAGE006
Tower, rectification III tower condenser, hydrogen fluoride recovery pump, rectification I tower top gaseous phase discharge gate and rectification I tower condenser feed inlet intercommunication, rectification I tower bottom discharge gate is outer to be connected the valve pipeline, continuous output waste liquid, rectification I tower condenser gaseous phase discharge gate and rectification II tower middle part gaseous phase feed inlet intercommunication, rectification I tower condenser liquid phase discharge gate and rectification I tower side top liquid phase feed back mouth intercommunication, rectification II tower middle part liquid phase feed inlet and between rectification I tower condenser liquid phase feed back mouth intercommunicationThe phase discharge port is communicated with a pipeline between a liquid phase feed back port at the top of the rectifying tower I, a gas phase discharge port at the top of the rectifying tower II is communicated with a feed inlet of a condenser of a rectifying tower II, the gas phase discharge port of the condenser of the rectifying tower II is externally connected with a hydrogen chloride absorption device, a liquid phase discharge port of the condenser of the rectifying tower II is communicated with a liquid phase feed back port at the top of the rectifying tower II, a discharge port at the bottom of the rectifying tower II is communicated with a feed inlet at the middle part of a rectifying tower III, a gas phase discharge port at the top of the rectifying tower III is communicated with a feed inlet of a condenser of a rectifying tower III, a liquid phase discharge port of the condenser of the rectifying tower III is communicated with a liquid phase feed back port at the side of the rectifying tower III, a discharge port at the bottom of the rectifying tower III is communicated with a;
the azeotrope-like extraction separation system comprises a static mixer, a phase separation condenser, a phase separator, a light phase tank, a light phase material pumping pump, a heavy phase material pumping pump and a rectification system
Figure DEST_PATH_IMAGE008
Column, rectifying IV column condenser and rectifying
Figure DEST_PATH_IMAGE010
A tower, a rectifying V-tower condenser, a tower bottom cooler, a 2-chloro-3, 3, 3-trifluoropropene crude product tank, a 2-chloro-3, 3, 3-trifluoropropene crude product feeding pump, a 3,3, 3-trifluoropropene caustic wash tower, a 3,3, 3-trifluoropropene crude product tank and a 2-chloro-3, 3, 3-trifluoropropene caustic wash tower, wherein a discharge port of the static mixer is communicated with a middle feed port of the phase separator through the phase separation condenser, a top light phase discharge port of the phase separator is communicated with a feed port of the light phase tank, a discharge port of the light phase tank is communicated with a middle feed port of the rectifying III tower through the light phase feeding pump, a bottom discharge port of the phase separator is communicated with a middle feed port of the rectifying IV tower through the heavy phase feeding pump, a top gas phase discharge port of the rectifying IV tower is communicated with a condenser feed port of the rectifying IV tower, a liquid phase discharge port of the rectifying IV condenser is communicated with a side top liquid, a pipeline between a liquid phase discharge port of a condenser of the rectification IV tower and a liquid phase feed back port at the top of the rectification IV tower side and a feed inlet of the static mixerA discharge port at the bottom of the rectification IV tower is communicated with a feed port at the middle part of a rectification V tower, a gas phase discharge port at the top of the rectification V tower is communicated with a feed port of a condenser of the rectification V tower, a liquid phase discharge port of the condenser of the rectification V tower is communicated with a liquid phase return port at the top of the rectification V tower, a pipeline between the liquid phase discharge port of the condenser of the rectification V tower and the liquid phase return port at the side of the rectification V tower is communicated with a feed port at the middle lower part of a 3,3, 3-trifluoropropene alkali wash tower, a discharge port at the top of the 3,3, 3-trifluoropropene alkali wash tower is communicated with a feed port at the top of a crude product tank of the 3,3, 3-trifluoropropene, a valve pipeline is connected outside the discharge port at the bottom of the 3, 3-trifluoropropene alkali wash tower, waste alkali liquor is continuously output, a, the top of the 2-chloro-3, 3, 3-trifluoropropene crude product tank is externally connected with a 2-chloro-3, 3, 3-trifluoropropene input valve pipeline, the bottom discharge port of the 2-chloro-3, 3, 3-trifluoropropene crude product tank is communicated with the middle upper feed port of the 2-chloro-3, 3, 3-trifluoropropene alkali wash tower through a 2-chloro-3, 3, 3-trifluoropropene crude product feeding pump, a pipeline between the 2-chloro-3, 3, 3-trifluoropropene crude product feeding pump and the 2-chloro-3, 3, 3-trifluoropropene alkali wash tower is communicated with the feed port of the static mixer through a valve, and the top discharge port of the 2-chloro-3, 3, 3-trifluoropropene alkali wash tower is externally connected with a valve pipeline to continuously output waste alkali liquor.
10. The apparatus for co-producing 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene according to claim 9, wherein the hydrogen fluoride vaporizer, the liquid chlorine vaporizer, and the tetrachloropropane preheater are provided with jackets into which steam is introduced for heating.
11. The apparatus for co-producing 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene according to claim 9, wherein a jacket is arranged outside the falling film evaporation premixer, and heat conducting oil is introduced into the jacket for heating;
the reactor is a fixed bed tubular reactor, a jacket is arranged at the lower end socket of the fixed bed tubular reactor, and heat conducting oil is introduced into the jacket for heating.
12. The apparatus for co-producing 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene according to claim 9, wherein the condenser of the rectification column II is cooled with a chilled saline water at a temperature ranging from-15 ℃ to-35 ℃, and the phase separation condenser is cooled with a chilled saline water at a temperature ranging from-15 ℃ to-35 ℃.
13. The apparatus for co-producing 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene according to claim 9, wherein the phase separator is provided with a jacket, and is cooled by introducing a chilled brine at a temperature of-15 ℃ to-35 ℃;
the middle upper part of the 3,3, 3-trifluoropropene alkali wash tower is connected with an alkali liquor input pipeline, and the middle lower part of the 2-chloro-3, 3, 3-trifluoropropene alkali wash tower is connected with an alkali liquor input pipeline.
14. A process for co-producing 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene using the apparatus of claim 9, comprising the steps of:
(1) reaction process
a) Pumping hydrogen fluoride to a hydrogen fluoride vaporizer for preheating by a hydrogen fluoride metering tank, b) pumping liquid chlorine to the liquid chlorine vaporizer for vaporization by a liquid chlorine metering tank, c) pumping 1,1,1, 3-tetrachloropropane to a tetrachloropropane preheater for preheating by a tetrachloropropane metering tank, and simultaneously and continuously introducing the preheated materials in the steps a), b) and c) into a falling film evaporation premixer; the hydrogen fluoride gas is excessively introduced, so that the vaporization partial pressure of the 1,1,1, 3-tetrachloropropane is effectively reduced, the 1,1,1, 3-tetrachloropropane is rapidly vaporized in the premixer, the premixer adopts a falling film evaporation premixer, and the continuous rapid vaporization and the full mixing of the mixed materials in the premixer are promoted; continuously introducing the vaporized and mixed materials into a fixed bed tubular reactor filled with a catalyst for reaction; after the reaction is finished, continuously discharging the mixed material from a discharge hole of the reactor, cooling the mixed material by a reaction cooler, and then feeding the cooled mixed material into a rectification pre-separation system;
(2) pre-separation by rectification
Continuously feeding the cooled mixed material from a middle feeding hole of a rectifying tower I, rectifying at positive pressure, condensing the tower top material by circulating water at 5-10 ℃ in a rectifying tower I condenser, refluxing, extracting a mixture of hydrogen fluoride, chlorine, 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene, continuously introducing the mixture into a middle liquid phase feeding hole of a rectifying tower II, continuously introducing uncondensed components of the rectifying tower I condenser, which are mainly hydrogen chloride and a small amount of chlorine, into a middle gas phase feeding hole of the rectifying tower II, continuously discharging high-boiling-point substances at the bottom of the rectifying tower I, taking the high-boiling-point substances as waste liquid, and transferring and burning the waste liquid; performing continuous positive pressure rectification in a rectification II tower, condensing the materials at the top of the tower by using frozen saline at the temperature of minus 30 to minus 35 ℃ in a rectification II tower condenser, refluxing, extracting hydrogen chloride and a small amount of chlorine, and feeding the hydrogen chloride and the small amount of chlorine into a hydrogen chloride absorption device; continuously discharging a mixture of hydrogen fluoride, 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene from the bottom of a rectification II tower, continuously inputting the mixture into a rectification III tower, rectifying at positive pressure, condensing circulating water at 5-10 ℃ in a condenser of the rectification III tower on the tower top, refluxing, extracting an azeotrope-like mixture, entering an azeotrope-like extraction and separation system, continuously discharging hydrogen fluoride from the bottom of the rectification III tower, and pumping the hydrogen fluoride to a hydrogen fluoride vaporizer for reuse by a hydrogen fluoride recovery pump;
(3) azeotrope-like extraction separation
Introducing an azeotrope-like mixture extracted from the top of a rectifying tower III into a static mixer, pumping a certain amount of 2-chloro-3, 3, 3-trifluoropropene into the static mixer from a 2-chloro-3, 3, 3-trifluoropropene crude product tank, fully mixing the 2-chloro-3, 3, 3-trifluoropropene serving as an extractant with the azeotrope-like mixture, cooling by a phase separation condenser with frozen brine at-30 ℃ to-35 ℃, allowing the mixture to enter a phase separator for standing and phase separation, introducing the frozen brine at-30 ℃ to-35 ℃ into a jacket of the phase separator for cooling and maintaining a certain positive pressure, discharging a light component phase from the upper part of the phase separator after phase separation, allowing the light component phase to enter a light phase tank, pumping the light phase to a rectifying tower III for use by a light phase material pump, wherein the recombinant phase comprises 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene and a small amount of hydrogen fluoride are discharged from the bottom of a phase separator, and are pumped to a rectification IV tower through a heavy phase material pump, the rectification IV tower is subjected to positive pressure rectification, the materials at the tower top are condensed by circulating water at the temperature of 5-10 ℃ in a rectification IV tower condenser and then flow back, the extracted azeotrope-like mixture is introduced into a static mixer for application, the mixture of 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene discharged from the tower bottom of the rectification IV tower enters a rectification V tower, the mixture is subjected to positive pressure rectification, the materials at the tower top are condensed by the circulating water at the temperature of 5-10 ℃ in a rectification V tower condenser and then flow back, the extracted 3,3, 3-trifluoropropene crude product is continuously introduced into a 3, 3-trifluoropropene alkali washing tower for alkali washing, the 2-chloro-3, 3, 3-trifluoropropene crude product is continuously output from the tower bottom of the rectification V tower, the 2-chloro-, 3, 3-trifluoropropene crude product tank;
feeding a 3,3, 3-trifluoropropene crude product from a feed inlet at the middle lower part of a 3,3, 3-trifluoropropene alkali wash tower, feeding alkali liquor from a feed inlet at the middle upper part of the 3,3, 3-trifluoropropene alkali wash tower, wherein positive pressure exists in the alkali wash tower, 3,3, 3-trifluoropropene is fully alkali washed, discharging from a discharge outlet at the top of the 3,3, 3-trifluoropropene alkali wash tower, feeding the discharged material into a 3,3, 3-trifluoropropene crude product tank, further rectifying and purifying to obtain a 3,3, 3-trifluoropropene product, and continuously discharging waste alkali liquor from the bottom of the 3,3, 3-trifluoropropene alkali wash tower for transfer treatment; pumping part of the 2-chloro-3, 3, 3-trifluoropropene crude product in the 2-chloro-3, 3, 3-trifluoropropene crude product tank to a static mixer for mixing and extracting, and washing the other part with alkali; feeding 2-chloro-3, 3, 3-trifluoropropene from a feed inlet at the middle upper part of a 2-chloro-3, 3, 3-trifluoropropene alkali wash tower, feeding alkali liquor from a feed inlet at the middle lower part of the 2-chloro-3, 3, 3-trifluoropropene alkali wash tower, and feeding positive pressure in the alkali wash tower to fully alkali wash the 2-chloro-3, 3, 3-trifluoropropene from a discharge outlet at the bottom of the 2-chloro-3, 3, 3-trifluoropropene alkali wash tower, further rectifying and purifying to obtain a 2-chloro-3, 3, 3-trifluoropropene product, and continuously discharging waste alkali liquor from the top of the 2-chloro-3, 3, 3-trifluoropropene alkali wash tower for transfer treatment.
15. The method for co-producing 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene according to claim 14, wherein the temperature in the falling film evaporation premixer in step (1) is 240 to 300 ℃, the working pressure is 1.0 to 1.3MPa, the molar ratio of chlorine gas to 1,1,1, 3-tetrachloropropane is 1:100 to 5:100, the molar ratio of hydrogen fluoride to 1,1,1, 3-tetrachloropropane is (10 to 50: 1), the reaction temperature is 240 to 300 ℃, and the reaction pressure is 1.0 to 1.3 MPa.
16. The method for co-producing 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene according to claim 14, wherein the operating pressures of the rectification column I and the rectification column II in the step (2) are 1.0 to 1.2MPa, and the operating pressure of the rectification column III is 0.8 to 1.0 MPa.
17. The process for co-producing 3,3, 3-trifluoropropene and 2-chloro-3, 3, 3-trifluoropropene according to claim 14, wherein the phase separator operating pressure in step (3) is 0.6 to 0.8MPa, the rectification IV column operating pressure is 0.6 to 1.0MPa, the rectification V column operating pressure is 0.5 to 0.8MPa, the 3,3, 3-trifluoropropene caustic scrubber operating pressure is 0.6 to 0.8MPa, and the 2-chloro-3, 3, 3-trifluoropropene caustic scrubber operating pressure is 0.4 to 0.6 MPa.
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