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CN-121990872-A - Method for simultaneously preparing vinylidene fluoride and fluoroethylene

CN121990872ACN 121990872 ACN121990872 ACN 121990872ACN-121990872-A

Abstract

The invention discloses a method for preparing vinylidene fluoride and vinyl fluoride simultaneously, which comprises the steps of reacting difluoroethane under the action of a catalyst and oxidizing gas to prepare the vinylidene fluoride and the vinyl fluoride, wherein the catalyst comprises an active component and a carrier compound, the active component comprises an active component A or an active component B, the active component A is selected from at least one of molybdenum salt, lanthanum salt, nickel salt, chromium salt, vanadium salt, platinum salt or palladium salt, and the active component B is selected from at least one of sodium salt, potassium salt, cesium salt, magnesium salt or calcium salt. The method takes difluoroethane as a raw material, and the vinylidene fluoride and the fluoroethylene are prepared simultaneously by reacting under the action of a catalyst and oxidizing gas.

Inventors

  • WANG JUNXING
  • LIU WUCAN
  • YU WANJIN
  • LI LING
  • ZHANG DI
  • CHENG MING
  • ZHANG JIANJUN

Assignees

  • 浙江蓝天环保高科技股份有限公司
  • 中化蓝天集团有限公司

Dates

Publication Date
20260508
Application Date
20241105

Claims (10)

  1. 1. A method for preparing vinylidene fluoride and vinyl fluoride simultaneously is characterized by comprising the steps of reacting difluoroethane under the action of a catalyst and oxidizing gas to prepare the vinylidene fluoride and the vinyl fluoride, wherein the catalyst comprises an active component and a carrier compound, and the active component comprises an active component A or the active component comprises an active component A and an active component B; The active component A is at least one of molybdenum salt, lanthanum salt, nickel salt, chromium salt, vanadium salt, platinum salt or palladium salt; the active component B is at least one selected from sodium salt, potassium salt, cesium salt, magnesium salt or calcium salt.
  2. 2. The method for simultaneously preparing vinylidene fluoride and vinyl fluoride by catalytic dehydrogenation of difluoroethane according to claim 1, wherein the total loading of active components in the catalyst is 0.1% -30%, the loading of active component A in the catalyst is 0.1% -25%, and the loading of active component B in the catalyst is 0% -5%.
  3. 3. The method for simultaneously preparing vinylidene fluoride and vinyl fluoride by catalytic dehydrogenation of difluoroethane according to claim 1, wherein the total loading of active components in the catalyst is 1% -10%, the loading of active component A in the catalyst is 1% -6%, and the loading of active component B in the catalyst is 0% -5%.
  4. 4. The method for the catalytic dehydrogenation of difluoroethane to simultaneously produce vinylidene fluoride and vinyl fluoride according to claim 1, wherein the oxidizing gas is at least one selected from the group consisting of oxygen, carbon dioxide and nitrous oxide.
  5. 5. The method for the catalytic dehydrogenation of difluoroethane to simultaneously produce vinylidene fluoride and vinyl fluoride according to claim 1, wherein the support compound is selected from at least one of titanium oxide, silicon carbide, boron nitride or molecular sieves.
  6. 6. The method for preparing vinylidene fluoride and vinyl fluoride simultaneously by catalytic dehydrogenation of difluoroethane according to any one of claims 1 to 5, wherein the catalyst is prepared by immersing a carrier compound in a soluble salt containing an active ingredient, drying, calcining and tabletting.
  7. 7. The method for preparing vinylidene fluoride and vinyl fluoride simultaneously by catalytic dehydrogenation of difluoroethane according to claim 6, wherein the soluble salt of the active component A is selected from the group consisting of chloride, nitrate, ammonium or sodium salts of molybdenum, lanthanum, nickel, chromium, vanadium, platinum or palladium, and the soluble salt of the active component B is selected from the group consisting of chloride, sulfate or nitrate salts of sodium, potassium, cesium, magnesium or calcium.
  8. 8. The method for simultaneously preparing vinylidene fluoride and vinyl fluoride by catalytic dehydrogenation of difluoroethane according to claim 6, wherein the calcination temperature is 300-800 ℃, and the tabletting is carried out under a pressure of 10-25 mpa.
  9. 9. A process for the simultaneous preparation of vinylidene fluoride and vinyl fluoride by catalytic dehydrogenation of difluoroethane according to any one of claims 1 to 5, characterized in that it comprises mixing as co-feed gas for the reaction a mixture comprising difluoroethane, an oxidizing gas and an inert gas, at a gas hourly space velocity of 500 to 20000mL/g cat h and at a temperature of 300 to 800 ℃.
  10. 10. The method for simultaneously preparing vinylidene fluoride and vinyl fluoride by catalytic dehydrogenation of difluoroethane according to claim 9, wherein the ratio of oxygen in the co-feed is 1.0% -35.0%, the partial pressure is controlled to be 0.01-2.0MPa, the ratio of nitrogen is controlled to be 20.0% -95.0%, preferably 40.0% -90.0%, and the partial pressure of difluoroethane is controlled to be 0.01-2.0MPa.

Description

Method for simultaneously preparing vinylidene fluoride and fluoroethylene Technical Field The invention relates to a preparation method of fluorine-containing olefin, in particular to a method for simultaneously preparing vinylidene fluoride and fluoroethylene. Background Vinylidene fluoride (VDF) is the main raw material of polyvinylidene fluoride (PVDF). PVDF is widely used in the fields of aerospace, high-end paint, new energy, environmental protection, medical treatment, scientific research and the like. PVDF has the characteristics of ageing resistance and easy processing, and has the chemical stability of high-strength fluorine resin and the easy processing of general resin in nature. In lithium batteries, PVDF is applied to a positive electrode binder and separator coating, and porous films, gels, separators, etc. made of PVDF resin are also applied to lithium secondary batteries, and this application has become one of the most rapidly growing markets for PVDF. At present, the preparation of vinylidene fluoride is not few, and patent (CN 114471653B) discloses that a Pt-deposited hollow carbon nitride microsphere catalyst can be used for preparing vinylidene fluoride by catalytic cracking of 1, 1-difluoro-chloroethane (HCFC-142B), and has low reaction temperature and simple operation. Patent (CN 111905779A) discloses that a catalyst based on BaF 2 is prepared by a hydrothermal method, and a large amount of alkaline earth, transition and lanthanide metals are introduced as cocatalysts to obtain different conversion rates of HCFC-142b and vinylidene fluoride selectivity. Patent (CN 113649032B) shows that the specific surface area of the alkaline earth metal fluoride catalyst can be greatly increased by combining a hydrothermal method and a coprecipitation method, so that the selectivity of vinylidene fluoride is improved. In the industrial production field, 1-difluoro chloroethane is mainly used as a raw material to prepare vinylidene fluoride by high-temperature pyrolysis of HCl, and the reaction is as follows, CH 3CF2Cl→CH2＝CF2 +HCl. At present, the conversion rate of the process and the selectivity of the vinylidene fluoride are ideal, the byproducts are few, the process production is flexible, a manufacturer can select a cracking process according to the own technical advantages, and the equipment is relatively simple and easy to maintain. However, the preparation of feedstock 142b requires an additional two steps of reacting acetylene with hydrogen fluoride to produce 1, 1-difluoroethane (HFC-152 a), followed by photochlorination of 152a to 142b as follows: C2H2+2HF→CH3CHF2(152a) CH3CHF2+Cl2→CF2ClCH3(142b)+HCl although the process is commonly used at present, the overall process is complex, the energy consumption is high, the production cost is high, the investment is also high, the service life of a cracking tube used in the cracking process is short, carbon is easy to form in the tube for coking, and the process has obvious limitation. In summary, the production and preparation of vinylidene fluoride are both from HCFC-142b, and the preparation of vinylidene fluoride monomer by catalytic dehydrogenation of R152a has higher energy efficiency, the route can save an independent process route of chlorination reaction, avoid using chlorine with extremely high danger, block the emission of highly corrosive byproduct HCl from the source, the catalyst is not easy to accumulate carbon in the reaction process, and the complicated steps of periodic decoking of cracking tubes are eliminated, and the process route is relatively simple. Unfortunately, the results of thermodynamic calculations indicate that R152a cannot be directly subjected to high temperature cracking dehydrogenation, and therefore, the reaction path of this reaction must be redesigned in order to achieve direct production of vinylidene fluoride from R152a, and on that basis, highly efficient catalytic R152a dehydrogenation catalysts have been developed and prepared. Disclosure of Invention The invention aims to provide a method for simultaneously preparing vinylidene fluoride and fluoroethylene, which takes difluoroethane as a raw material and simultaneously prepares the vinylidene fluoride and the fluoroethylene by reaction under the action of a catalyst and oxidizing gas. The technical scheme of the invention is as follows: A method for preparing vinylidene fluoride and vinyl fluoride simultaneously comprises the steps of reacting difluoroethane under the action of a catalyst and oxidizing gas to obtain the vinylidene fluoride and the vinyl fluoride, wherein the catalyst comprises an active component and a carrier compound, and the active component comprises an active component A or the active component comprises an active component A and an active component B; The active component A is at least one of molybdenum salt, lanthanum salt, nickel salt, chromium salt, vanadium salt, platinum salt or palladium salt; the active component B is at