Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • 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
  • C07C17/202—Preparation of halogenated hydrocarbons by replacement by halogens of halogen atoms by other halogen atoms two or more compounds being involved in the reaction
  • C07C17/206—Preparation of halogenated hydrocarbons by replacement by halogens of halogen atoms by other halogen atoms two or more compounds being involved in the reaction the other compound being HX
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
  • B01J23/002—Mixed oxides other than spinels, e.g. perovskite
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
  • B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
  • B01J23/24—Chromium, molybdenum or tungsten
  • B01J23/26—Chromium
• • 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
  • C07C17/42—Use of additives, e.g. for stabilisation
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C19/00—Acyclic saturated compounds containing halogen atoms
  • C07C19/08—Acyclic saturated compounds containing halogen atoms containing fluorine
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2523/00—Constitutive chemical elements of heterogeneous catalysts

Definitions

• the present invention relates to a process for the production of 1,1,1 - trifluoroethane (HFC-143a).
• HFC-143a is used as a component of refrigerant mixtures replacing chlorofluorocarbons.
• Patent application EP-A-714 874 describes the manufacture of HFC-143a from 1,1-Difluoro-1-chloroethane (HCFC-142b) in the vapor phase with an HF / HCFC-142b molar ratio greater than 1.
• the European patent EP-B-714874 teaches that this ratio must be at least 1.3 to avoid the formation of by-products by decomposition of HCFC-142b.
• the invention therefore relates to a process for the production of 1,1,1-trifluoroethane (HFC-143a), according to which 1,1-Difluoro-1-chloroethane (HCFC-142b) is subjected to a vapor phase reaction with hydrogen fluoride (HF) in the presence of a hydrofluorination catalyst, process in which the molar ratio between HCFC-142b and HF introduced into the reaction in the vapor phase is greater than or equal to 1 and less than 1 3.
• HFC-143a 1,1,1-trifluoroethane
• HCFC-142b 1,1-Difluoro-1-chloroethane
• HF hydrogen fluoride
• the HF / HCFC-142b molar ratio is often greater than or equal to 1.02. Preferably, this molar ratio. is greater than or equal to 1.05.
• the HF / HCFCr • 142b molar ratio is often less than or equal to 1.25. Preferably, this molar ratio is less than or equal to 1.20.
• the temperature is generally greater than or equal to 100 ° C. Preferably, the temperature is greater than or equal to 150 ° C. In the process according to the invention, the temperature is generally less than or equal to 400 ° C. Preferably, the temperature is less than or equal to 250 ° C.
• the pressure is generally greater than or equal to 1 bar. Preferably, the pressure is greater than or equal to 5 bar. In the process according to the invention, the pressure is generally less than or equal to 30 bar. Preferably, the pressure is less than or equal to 15 bar.
• the contact time defined as the ratio between the volume of the catalyst divided by the flow rate of HF and HCFC-142b introduced into the reactor is generally greater than or equal to ls. Preferably, the contact time is greater than or equal to 10 s. In the process according to the invention, the contact time defined as the ratio between the volume of the catalyst divided by the flow rate of HF and HCFC-142b introduced into the reactor is generally less than or equal to 200 s. Preferably, the contact time is less than or equal to 50 s.
• the hydrofluorination catalyst can be chosen, for example, from supported or unsupported metal salts. Where appropriate, the support can be, for example, activated carbon.
• the hydrofluorination catalyst can advantageously comprise chromium oxide.
• the amorphous chromium oxide present, before any pre-fluorination treatment generally has a BET / N 2 specific surface of less than or equal to 600 m / g, preferably less than or equal to 400 m 2 / g.
• a particularly preferred catalyst for use in the process according to the invention contains chromium and magnesium. This catalyst can be obtained by a method according to which
• step (d) the dried pulp is subjected to a treatment with hydrogen fluoride at temperatures of 20 to 500 ° C; and the quantities of water-soluble chromium salt (LTI), magnesium hydroxide or magnesium oxide and optionally graphite are chosen in such a way that the dried paste obtained in step (c) contains 3, 5 to 26% by weight, preferably 4.5 to 23% by weight of chromium expressed in the form of Cr2O3, at least 25% by weight of magnesium expressed in the form of MgO and optionally graphite preferably in an amount of 5 to 40% by weight.
• LTI water-soluble chromium salt
• MgO magnesium hydroxide
• optionally graphite optionally graphite
• the molar ratio between HCFC-142b and HF introduced into the vapor phase reaction is greater than or equal to 1.3.
• such a ratio may be implemented greater than or equal to 2.
• the molar ratio between the HCFC-142b and the HF introduced into the reaction in the vapor phase is generally less than or equal to 10.
• this ratio is less than or equal to 5.
• the HCFC-142b used as starting material in the process according to the invention is commercially available. Alternatively, it can be obtained by hydrofluorination from vinylidene chloride or 1,1,1-trichloroethane or their mixtures.
• the stream of reactants introduced into the vapor phase reaction preferably consists essentially of HCFC-142b and hydrogen fluoride.
• Other compounds such as in particular 1,1-dichloro-1-fluoroethane may optionally be present in the stream of reactants introduced into the reaction in the vapor phase.
• the content of such compounds is less than 5 mol% relative to the sum of moles of compounds present in the reactant stream. A content of less than 1 mol% is more particularly preferred.
• the method according to the invention can be carried out in continuous or discontinuous mode.
• a continuous process is preferred.
• the process according to the invention can be implemented in any reactor suitable for carrying out a hydrofluorination process in the vapor phase.
• a tabular reactor made of materials resistant to presence of HF at reaction temperature and pressure, containing a fixed catalyst ht.
• the catalyst was dried for 1 hour at 150 ° C under a nitrogen sweep at a flow rate of 10N 2 / h.
• the catalyst was then fluorinated by an HF / N 2 mixture
• HCFC-142b and HF continuously.
• the HF / HCFC-142b ratio introduced was 1.1.
• the reaction pressure was 10 bar.
• a gas phase was recovered containing HFC-143a which was introduced into a washing column to remove the excess HF and the C1H produced by washing with an aqueous solution of OH.
• the gas leaving this wash analyzed by vapor phase chromatography.
• the conversion of HCFC-142b was 93.5% and the selectivity to HFC-143a was 99.5%.
• the reaction was continued for 600 h without loss of activity or selectivity.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Catalysts (AREA)
• Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)

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Publications (1)

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Citations (6)

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• 2003
  • 2003-03-07 FR FR0303027A patent/FR2852007B1/fr not_active Expired - Fee Related
• 2004
  • 2004-03-05 EP EP04717641A patent/EP1603854A1/fr not_active Withdrawn
  • 2004-03-05 US US10/548,338 patent/US20060189835A1/en not_active Abandoned
  • 2004-03-05 JP JP2006504638A patent/JP2006520762A/ja active Pending
  • 2004-03-05 CN CNB200480006213XA patent/CN100471828C/zh not_active Expired - Fee Related
  • 2004-03-05 WO PCT/EP2004/002499 patent/WO2004078684A1/fr not_active Ceased
  • 2004-03-05 KR KR1020057016592A patent/KR20050120634A/ko not_active Ceased

Patent Citations (6)

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