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CN-121988244-A - Device and method for preparing 1-chloro-1, 1-difluoroethane

CN121988244ACN 121988244 ACN121988244 ACN 121988244ACN-121988244-A

Abstract

The invention discloses a device and a method for preparing 1-chloro-1, 1-difluoroethane, wherein the device comprises a reactor, a1, 1-difluoroethane feed inlet and a multi-stage chlorine feed inlet are arranged on the reactor, the 1, 1-difluoroethane feed inlet is arranged at the top of the reactor, the multi-stage chlorine feed inlet is respectively arranged at the top and the side wall of the reactor, and a gas outlet is arranged at the bottom of the reactor. The method for preparing the 1-chloro-1, 1-difluoroethane is realized by the device, and the preparation method is a thermal chlorination method. According to the invention, the 1-chloro-1, 1-difluoroethane reactor is skillfully designed, and the multistage chlorine feed inlet is arranged on the reactor, so that chlorine is added in stages, the temperature in the reactor is effectively controlled, the reaction process is controlled, and the generation of byproducts is reduced. The device for preparing the 1-chloro-1, 1-difluoroethane has the advantages of simple structure, high mass and heat transfer efficiency, high raw material utilization rate, high yield of target products and the like, and can realize industrial continuous production.

Inventors

  • ZHANG WANHONG
  • HUANG MINGXING
  • LI HONGFENG
  • XU XIAOBO
  • WANG ZONGLING
  • Lv Chanjun

Assignees

  • 浙江巨化技术中心有限公司

Dates

Publication Date
20260508
Application Date
20241104

Claims (17)

  1. 1. The device for preparing the 1-chloro-1, 1-difluoroethane is characterized by comprising a reactor, wherein a1, 1-difluoroethane feed inlet and a multi-stage chlorine feed inlet are arranged on the reactor, the 1, 1-difluoroethane feed inlet is arranged at the top of the reactor, the multi-stage chlorine feed inlet is respectively arranged at the top of the reactor and on the side wall of the reactor, and a gas outlet is arranged at the bottom of the reactor.
  2. 2. The apparatus of claim 1, wherein the number of the multi-stage chlorine feed inlets is 2 to 4, wherein one chlorine feed inlet is located at the top of the reactor and the remaining chlorine feed inlets are located on the side wall of the reactor.
  3. 3. The apparatus of claim 1 wherein the number of said multi-stage chlorine feed inlets is 2, including a primary chlorine feed inlet at the top of the reactor and a secondary chlorine feed inlet at the side wall of the reactor.
  4. 4. The apparatus of claim 1 wherein the number of said multi-stage chlorine feed inlets is 3 and comprises a primary chlorine feed inlet at the top of the reactor, a secondary chlorine feed inlet at the side wall of the reactor and a tertiary chlorine feed inlet.
  5. 5. The apparatus of claim 1 wherein the chlorine feed openings in the side wall of the reactor are equally spaced along the side wall of the reactor.
  6. 6. The apparatus of claim 1 wherein the chlorine feed to the side wall of the reactor is disposed on the same side of the side wall of the reactor.
  7. 7. The apparatus of claim 1, wherein the reactor is a tubular reactor, including a straight tube reactor, a spiral tube reactor, or a shell-and-tube reactor.
  8. 8. The apparatus of claim 7, wherein the length-to-diameter ratio of the tubular reactor is 400-2500:1.
  9. 9. The apparatus of claim 8, wherein the tubular reactor is a spiral tubular reactor having an aspect ratio of 500-2000:1.
  10. 10. The apparatus of claim 1, wherein the reactor is made of one of glass, nickel, ceramic, stainless steel, hastelloy, inconel or silicon carbide.
  11. 11. A process for the preparation of 1-chloro-1, 1-difluoroethane, carried out using the apparatus according to any one of claims 1 to 10, comprising the steps of: (1) Preheating 1, 1-difluoroethane, introducing the 1, 1-difluoroethane from a1, 1-difluoroethane feed inlet at the top of the reactor, introducing chlorine from a multi-stage chlorine feed inlet at the top of the reactor and on the side wall of the reactor, and reacting to obtain a reaction mixture; (2) The reaction mixed gas enters a cooler from the outlet at the bottom of the reactor to be cooled, and is rectified after alkali absorption, defoaming and drying to obtain the 1-chloro-1, 1-difluoroethane.
  12. 12. The preparation method of claim 11, wherein the molar ratio of the chlorine amount introduced into the chlorine gas feed inlet at the top of the reactor to the chlorine amount introduced into each chlorine gas feed inlet on the side wall of the reactor is 1:0.5-1.
  13. 13. The process according to claim 11 or 12, wherein the molar ratio of 1, 1-difluoroethane to total chlorine entering the reactor is 1:0.5 to 1.2.
  14. 14. The method according to claim 11, wherein the preheating temperature of the 1, 1-difluoroethane and the chlorine gas is 50-250 ℃.
  15. 15. The method according to claim 11, wherein the temperature of the reactor is 250-500 ℃ and the pressure is 0-1 mpa.
  16. 16. The method according to claim 11, wherein the reactor is a spiral tube reactor, the number of the multi-stage chlorine gas feed inlets is 2, the multi-stage chlorine gas feed inlets are respectively positioned at the top of the reactor and the middle part of the side wall of the reactor, the length-diameter ratio of the spiral tube reactor is 700-1000:1, the feed ratio of the primary chlorine gas to the secondary chlorine gas is 1:0.8-1, the molar ratio of the 1, 1-difluoroethane to the total chlorine gas entering the reactor is 1:0.8-1.2, the preheating temperature is 150-170 ℃, the temperature of the spiral tube reactor is 350-430 ℃, and the pressure is 0.3-0.5 MPa.
  17. 17. The process of claim 16 wherein the spiral tube reactor has an aspect ratio of 1000:1, the primary to secondary chlorine feed ratio is 1:1, the molar ratio of 1, 1-difluoroethane to total chlorine entering the reactor is 1:1, the preheat temperature is 170 ℃, the spiral tube reactor temperature is 400 ℃, and the pressure is 0.3 MPa.

Description

Device and method for preparing 1-chloro-1, 1-difluoroethane Technical Field The invention relates to the field of organic synthesis, in particular to a device and a method for preparing 1-chloro-1, 1-difluoroethane. Background 1, 1-Difluoro-1-chloroethane has a molecular formula of CClF 2CH3, HCFC-142b for short, and R142b for common name. Is colorless gas at normal temperature, has slightly aromatic flavor, is easily dissolved in oil and water, and has boiling point of-9.2 ℃ (101.31 kPa). HCFC-142b is an important organic intermediate, can be used for producing vinylidene fluoride monomer (VDF) and then producing polyvinylidene fluoride (PVDF) resin, and PVDF is a high polymer material with good comprehensive properties, and is widely applied to the fields of electronic appliances, aerospace, acoustic equipment, medical appliances, optical instruments and the like. The synthesis of HCFC-142b mainly comprises three methods, namely a direct fluoro method, a vinylidene chloride addition fluorination method and a1, 1-difluoroethane photochlorination method. (1) Direct fluorination process The direct fluoridation method uses 1, 1-trichloroethane as raw material, and makes them directly undergo the fluoridation reaction with hydrogen fluoride under a certain condition. The reaction equation is as follows: CH3CCl3+HF→CH3CFCl2+HCl CH3CFCl2+HF→CH3CF2Cl+HCl Patent CN1030746a discloses and reports that 1, 1-difluoro-1-chloroethane is prepared by liquid phase fluorination reaction using 1, 1-trichloroethane or 1, 1-dichloro-1-fluoroethane and hydrofluoric acid as raw materials and perfluoro alkyl sulfonic acid (trifluoromethane sulfonic acid) as catalyst. With this catalyst, the conversion of 1, 1-trichloroethane as a raw material was 98.5%, and the selectivity of 1, 1-difluoro-1-chloroethane was 64.4%. In the method, the 1, 1-trichloroethane is very active in self-group trichloromethyl, and even without a catalyst, the fluoro reaction can occur, so that the reaction degree is difficult to control. If no catalyst is used in the reaction, the required reaction temperature is higher, excessive hydrogen fluoride can cause excessive byproducts in the reaction products, and too little hydrogen fluoride can cause the reduction of the reaction rate and the extension of the reaction time. (2) Vinylidene chloride addition fluorination process The vinylidene chloride addition fluorination process is a process for obtaining 1, 1-difluoro-1-chloroethane by using 1, 1-dichloroethylene (VDC) and hydrogen fluoride as raw materials and performing addition fluorination reaction under certain conditions. The equation is as follows: CH2＝CCl2+HF→CH3CCl2F CH3CCl2F+HF→CH3CF2Cl+HCl Patent CN1171837C discloses a method for preparing R124b by a one-step liquid phase reaction by taking VDC and hydrogen fluoride as raw materials and SnCl 4、CF3(CF2)3 COF as a catalyst, wherein the selectivity of R142b reaches 95.2%, but the heat release is severe in the experimental process, and the utilization rate of the hydrogen fluoride is low. US5159126a discloses a process for the preparation of 1-chloro-1, 1-difluoroethane starting from VDC and hydrogen fluoride, tin tetrachloride as catalyst to synthesize HCFC-142b in the liquid phase, and the mixture of VDC-and HF is heated to 60 ℃ in an autoclave to yield HCFC-141b at a mass fraction of 64.8%, HCFC-142b at 26.7%, HFC-143a at 2.1%, 1-trichloroethane at 0.8% and oligomers at 1.4%, unreacted VDC at 4.2%, respectively. CN1927790a discloses a method for producing 1-chloro-1, 1-difluoroethane by using vinylidene chloride and hydrogen fluoride as raw materials, VDC and hydrogen fluoride as raw materials and SnCl 4 as catalysts to make liquid phase reaction, and adopting a cyclic reaction rectification mode to complete synthesis and separation of difluoromonochloroethane in the same equipment. (3) 1, 1-Difluoroethane photochlorination process The 1, 1-difluoroethane photochlorination method is to take 1, 1-difluoroethane and chlorine as raw materials, and react under ultraviolet light to obtain 1-chloro-1, 1-difluoroethane. The equation is as follows: CH3CHF2+Cl2→CH3CF2Cl+HCl CN101456788B discloses a method for preparing difluorochloroethane by photocatalysis, which comprises (1) gasifying liquid chlorine and difluoroethane in a gasifier, mixing in the mixer, lining polytetrafluoroethylene on the inner wall of the mixer, filling porcelain on the upper part of the mixer, (2) introducing the mixed gas into a photocatalysis reactor, wherein the pressure in the photocatalysis reactor is 0.1-0.12MPa, the temperature is 80-100 ℃, the molar flow-rate ratio of the chlorine to the difluoroethane is 1:1 in the introduced gas, the flow rate of the mixed gas of the chlorine and the difluoroethane in the photocatalysis reactor is 0.085-0.09m/s, the reaction time is 85-105s, and (3) carrying out water washing and alkali washing on the reacted gas to absorb unreacted chlorine and hydrogen chloride generated by the reaction,