Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C17/00—Preparation of halogenated hydrocarbons
  • C07C17/26—Preparation of halogenated hydrocarbons by reactions involving an increase in the number of carbon atoms in the skeleton
  • C07C17/272—Preparation of halogenated hydrocarbons by reactions involving an increase in the number of carbon atoms in the skeleton by addition reactions
  • C07C17/275—Preparation of halogenated hydrocarbons by reactions involving an increase in the number of carbon atoms in the skeleton by addition reactions of hydrocarbons and 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
• • 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
  • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
  • B01J27/06—Halogens; Compounds thereof
  • B01J27/08—Halides
  • B01J27/10—Chlorides
• • 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
  • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
  • B01J27/06—Halogens; Compounds thereof
  • B01J27/08—Halides
  • B01J27/12—Fluorides
• • 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
  • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
  • B01J27/06—Halogens; Compounds thereof
  • B01J27/138—Halogens; Compounds thereof with alkaline earth metals, magnesium, beryllium, zinc, cadmium or mercury
• • 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
  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/19—Catalysts containing parts with different compositions
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07B—GENERAL METHODS OF ORGANIC CHEMISTRY; APPARATUS THEREFOR
  • C07B35/00—Reactions without formation or introduction of functional groups containing hetero atoms, involving a change in the type of bonding between two carbon atoms already directly linked
  • C07B35/06—Decomposition, e.g. elimination of halogens, water or hydrogen halides
• • 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
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C21/00—Acyclic unsaturated compounds containing halogen atoms
  • C07C21/02—Acyclic unsaturated compounds containing halogen atoms containing carbon-to-carbon double bonds
  • C07C21/18—Acyclic unsaturated compounds containing halogen atoms containing carbon-to-carbon double bonds containing fluorine

Definitions

• the present invention relates to the dehydrohalogenation of a halogen-containing compound.
• the present invention further relates to the dehydrochlorination of a hydrochlorofluorocarbon to a fluorinated olefin.
• Chlorine-containing compounds such as chlorofluorocarbons (CFCs) have been employed as refrigerants, foam blowing agents, cleaning agents, solvents, heat transfer media, sterilants, aerosol propellants, dielectrics, fire extinguishing agents, and power cycle working fluids.
• CFCs chlorofluorocarbons
• Conventional substitutes for CFCs include hydro fluorocarbons (HFCs); however, these compounds have been found to contribute to global warming. For these reasons, there is a worldwide effort to develop new compounds that are environmentally benign.
• fluorinated olefins including hydrofluoroolefins
• fluorinated olefins are potential replacements for HFCs and CFCs. They can be used in some of the aforementioned applications and can also be used as feedstock monomers to synthesize fluoropolymers and other macromolecular compounds.
• Various methods for producing certain fluorinated olefins are known, including those involving the dehydrochlorination of hydrochlorofluorocarbons. For example, US Patent Application No.
• 11/619,592 discloses a method for preparing 2,3,3,3-tetrafluoropropene (1234yf) via dehydrochlorination of 1,1,1,2-tetrafluoro-2-chloropropane (244bb) with the aid of a catalyst.
• the '592 application also teaches the use of a carbon- and/or metal-based catalyst for the conversion of 244bb to 1234yf.
• the conversion of 244bb could be as high as 98%, but has a selectivity for 1234yf of only 69% to 86%.
• a process for making a fluorinated olefin via dehydrochlorination of a hydrochlorofluorocarbon having at least one hydrogen atom and at least one chlorine atom on adjacent carbon atoms is carried out in the presence of a catalyst selected from the group consisting of (i) one or more metal halides, (ii) one or more halogenated metal oxides, (iii) one or more zero-valent metals/metal alloys, and (iv) a combination of two or more of the foregoing.
• Preferred fluorinated olefin products are the following: 2,3,3,3-tetrafluoropropene (1234yf), 1,3,3,3-tetrafluoropropene (trans/cis-1234ze), 1,2,3,3,3-pentafluoropropene (Z/E-1255ye), 1,1,3,3,3-pentafluoropropene (1225zc), and 1,1,2,3,3,3-hexafluoropropene (1216).
• a hydrochlorofluorocarbon having at least one hydrogen and at least one chlorine on adjacent carbons is dehydrochlorinated in the presence of a catalyst to form a product having a fluorinated olefin therein.
• Table 1 sets forth examples of fluorinated olefins and precursor hydrochlorofluorocarbons from which they can be obtained (i.e., hydrochlorofluorocarbon in left column and corresponding fluorinated olefin in the right column).
• selected catalysts are employed to enhance the selectivity and/or conversion of hydrochlorofluorocarbons to fluorinated olefins.
• the catalysts are more selective for the dehydrochlorination reaction, which produces fluorinated olefin, than for the competing dehydrofluorination side reaction, which produces the undesirable byproduct chlorine-containing olefin.
• the first class of catalysts is metal halides, preferably mono-, bi-, and tri-valent metal halides and their mixtures/combinations, and more preferably mono- and bi-valent metal halides and their mixtures/combinations.
• Component metals include, but are not limited to, Cr 3+ , Fe 3+ , Mg 2+ , Ca 2+ , Ni 2+ , Zn 2+ , Pd 2+ , Li + , Na + , K + , and Cs + .
• Component halogens include, but are not limited to, F-, Cl-, Br-, and I-.
• Examples of useful mono- or bi-valent metal halide include, but are not limited to, LiF, NaF, KF, CsF, MgF 2 , CaF 2 , LiCl, NaCl, KCl, and CsCl.
• the catalyst may be supported or unsupported.
• a preferred catalyst is a CsCl/MgF 2 combination.
• a particularly preferred catalyst is a CsCl/MgF 2 combination wherein CsCl is present in an amount of about 5.0 to about 50 wt % based on the total weight of the catalyst.
• the second class of catalysts is halogenated metal oxides, preferably halogenated mono-, bi-, and tri-valent metal oxides and their mixtures/combinations, and more preferably halogenated mono- and bi-valent metal oxides and their mixtures/combinations.
• Component metals include, but are not limited to, Cr 3+ , Fe 3+ , Mg 2+ , Ca 2+ , Ni 2+ , Zn 2+ , Pd 2+ , Li + , Na + , K + , and Cs + .
• Halogenation treatments can include any of those known in the prior art, particularly those that employ HF, F 2 , HCl, Cl 2 , HBr, Br 2 , HI, and I 2 as the halogenation source.
• useful halogenated mono- and bi-valent metal oxides include, but are not limited to, fluorinated or chlorinated MgO, fluorinated or chlorinated CaO, fluorinated or chlorinated Li 2 O, fluorinated or chlorinated Na 2 O, fluorinated or chlorinated K 2 O, and fluorinated or chlorinated Cs 2 O.
• the catalyst may be supported or unsupported.
• the third class of catalysts is neutral (i.e., zero valent) metals, metal alloys, and their mixtures.
• Useful metals include, but are not limited to, Pd, Pt, Rh, Fe, Co, Ni, Cu, Mo, Cr, Mn, and combinations of the foregoing as alloys or mixtures.
• the catalyst may be supported or unsupported.
• Useful examples of metal alloys include, but are not limited to, SS 316, Monel 400, Inconel 825, Inconel 600, and Inconel 625.
• the product mixture may also have unconverted hydrochlorofluorocarbon and hydrogen chloride.
• Enhanced or improved selectivity for the target product is an important feature of the present invention.
• the dehydrochlorination reaction is preferably carried out at a selectivity of at least about 50%, more preferably at least about 70%, and most preferably at least about 80%. Conversion is preferably about 25% or more and most preferably about 40% or more. Dehydrochlorination may be carried out at a temperature range of about 200°C to about
• reaction pressures may be used, such as superatmospheric, atmospheric, and subatmospheric. Atmospheric pressure is preferred.
• Dehydrochlorination may optionally be carried out in presence or absence of an oxidizing agent.
• oxidizing agents include, but are not limited to, oxygen and carbon dioxide.
• Use of an oxidizing agent can extend the life of the catalyst.
• the oxidizing agent can be pure or diluted with an inert gas such as nitrogen before being introduced into reactor.
• the level of oxidizing agent is generally from about 1% to about 10% by volume and preferably from about 2% to 5% by volume based on the volume of the organic feed.
• Regeneration of the catalyst may be accomplished by any means known in the art.
• One method is by passing oxygen or oxygen diluted with nitrogen over the catalyst at temperatures of about 200°C to about 600°C (preferably about 350°C to about 450°C) for about 0.5 hour to about 3 days followed by either halogenation treatment at temperatures of about 25°C to about 400°C (preferably about 200°C to about 350°C) for halogenated metal oxide catalysts and metal halide ones or reduction treatment at temperatures of about 100°C to about 600°C (preferably about 200°C to about 350°C) for metal catalysts.
• Dehydrochlorination is preferably carried out in a corrosion-resistant reaction vessel.
• corrosion-resistant materials are Hastelloy, Inconel, Monel and fluoropolymer linings.
• the vessel may have a fixed or a fluidized catalyst bed. If desired, inert gases such as nitrogen or argon may be employed in the reactor during operation.
• Example 1 244bb dehydrohalogenation over metal fluoride and fluorinated metal oxide catalysts
• a series of mono-, bi-, and tri-valent metal fluorides and fluorinated bi- and tri-valent metal oxides were used as dehydrohalogenation catalysts. Approximately 20 cc of catalyst pellets was used in a typical run. A mixture containing 97.2 wt. % 244bb and 2.0 wt. % 1233xf was passed through the catalyst bed at a rate of 6 g/h at a temperature that ranged from 200°C to 600°C. The temperatures at the bottom of catalyst bed and at the top of catalyst bed were measured.
• MgF 2 exhibited the best performance; it provided a conversion of 244bb above 50% and a selectivity to 1234yf above 85% after 8 h (hours) on stream.
• Example 2 244bb dehydrohalogenation over alkaline metal chloride-doped MgF 2 catalysts
• a series of alkaline metal chlorides were investigated as an additive to MgF 2 with a purpose of improving the selectivity to 1234yf.
• the results obtained over MgF 2 catalyst were also reported.
• Approximately 20 cc of catalyst pellets was used in a typical run.
• a mixture containing 97.2 wt. % 244bb and 2.0 wt. % 1233xf was passed through catalyst bed at a rate of 6 g/h (grams/hour) at a temperature that ranged from 470°C to 520°C. The temperatures at the bottom of catalyst bed and at the top of catalyst bed were measured.
• the MgF 2 provided a 244bb conversion of 53-55%, a 1234yf selectivity of 80-87%, and a 1233xf selectivity of 8-15%; the 10% LiCl/MgF 2 provided a 244bb conversion below 45%, a 1234yf selectivity of about 90%, and a 1233xf selectivity of about 5%; the 10% KCl/MgF 2 provided a 244bb conversion below 50%, a 1234yf selectivity of about 96%, and a 1233xf selectivity of about 1%; and the 10% CsCl/MgF 2 provided a 244bb conversion of 50-52%, a 1234yf selectivity of about 97%, and essentially no formation of 1233xf. CsCl exhibited the best results, while the 10% CsCVMgF 2 catalyst provided activity comparable to MgF 2 and the highest 1234yf selectivity while generating no 1233xf.
• the 12 wt% NiZMgF 2 catalyst provided a 1234yf selectivity of about 95% with a 1233xf selectivity of about 2%.
• a series of supported and unsupported metals as well as metal alloys were used as dehydrohalogenation catalysts. 20 cc of catalyst pellets or a 4 inch- long metal mesh roll was used in a typical run. A mixture containing 97.2 wt. % 244bb and 2.0 wt. % 1233xf was passed through a catalyst bed at a rate of 6 g/h at a temperature ranged from 420°C to 480°C. The temperatures at the top and bottom of the catalyst bed were measured. As shown in Table 6, all the metal and metal alloy catalysts were active and extremely selective for 244bb dehydrochlorination (1234yf selectivity > 95%) while generating no 1233xf. Compared to metal halide and/or halogenated metal oxide catalysts, the metal catalysts did not require as high an operating temperature.

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