Classifications

• • 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
  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/22—Halogenating
  • B01J37/26—Fluorinating
• • 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
  • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
  • B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
  • B01J23/84—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
  • B01J23/85—Chromium, molybdenum or tungsten
  • B01J23/86—Chromium
  • B01J23/866—Nickel and chromium
• • 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
  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/02—Impregnation, coating or precipitation
  • B01J37/0201—Impregnation
  • B01J37/0207—Pretreatment of the support
• • 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
  • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
  • B01J21/02—Boron or aluminium; Oxides or hydroxides thereof
  • B01J21/04—Alumina
• • 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
  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J35/61—Surface area
  • B01J35/613—10-100 m2/g
• • 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
  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J35/63—Pore volume
  • B01J35/633—Pore volume less than 0.5 ml/g

Definitions

• the subject of the invention is a process for the preparation of fluorinated compounds, in particular the fluorinated compounds 1225ye and 1234yf.
• Hydrofluorocarbons (HFCs) and in particular hydrofluoroolefins, such as 2,3,3,3-tetrafluoro-1-propene (HFO 1234yf) are compounds known for their properties as refrigerants and heat-transfer fluids, extinguishers, propellants, foaming agents, blowing agents, gaseous dielectrics, polymerization medium or monomer, carrier fluids, abrasive agents, drying agents and fluids for power generation units.
• HFOs do not contain chlorine and therefore do not pose a problem for the ozone layer.
• WO2008 / 002499 discloses a process for producing a mixture of 2,3,3,3-tetrafluoro-1-propene (HFO 1234yf) and 1,3,3,3-tetrafluoro-1-propene (HFO 1234ze) by pyrolysis of 1,1,1,2,3-pentafluoropropane (HFC 245eb).
• the temperatures used are described as being 450 ° C. to 900 ° C., and in general 600 ° C. to 750 ° C., which are the temperatures used in the examples.
• the ratio of products 1234yf: 1234ze is about 1.3-1.4.
• WO 2008/002500 discloses a process for producing a mixture of 2,3,3,3-tetrafluoro-1-propene (HFO 1234yf) and 1, 3, 3-tetrafluoro-1-propene (HFO 1234ze) by catalytic conversion of 1, 1, 1, 2, 3-pentafluoropropane (HFC 245eb) on a dehydrofluorination catalyst.
• the preferred dehydrofluorination catalyst is fluorinated alumina or aluminum fluoride (oxyfluoride and aluminum fluoride), the catalyst used in the example being 1 Oxyfluoride. • " " " " " " JJOO • [_
• dehydrofluorination catalysts selected from oxides, fluorides and oxyfluorides of various metals, including chromium and nickel. No examples of these catalysts are given.
• the temperatures used are described as being from 200 ° C. to 500 ° C., and in general from 300 ° C. to 450 ° C., the highest conversions being obtained at 400 ° C. and more in the examples.
• the 1234yf: 1234ze product ratio is about 1.9-2.0.
• WO 2007/056194 describes the preparation of HFO by conversion of a compound of formula (I) CF 3 CHXCH 2 X into a compound of formula (II) CF 3 CZCHZ, in which formula X is independently Cl or F, and Z is independently H or F. It is indicated that the selectivity to certain compounds, such as in particular tetrafluoropropene, and more preferably still HFO-1234yf and / or HFO-1234ze, and at least 70%, preferably at least 80%.
• the reaction takes place in the gas phase, on a catalyst.
• the catalysts described in this application are catalysts, for example FeCl 3 , chromium oxyfluoride, Ni
• a preferred embodiment is the preparation of 1234yf by dehydrohalogenation of 245eb, especially on nickel-based catalyst, carbon or a combination thereof. The temperature indicated as appropriate is between
• Examples 1-16 of WO2007 / 056194 give several catalysts and temperature conditions for the reaction, with varying conversions and selectivities. At equal catalyst, the increase in temperature leads to an increase in conversion but accompanied by a concomitant decrease in selectivity, thus affecting yield in 1234yf.
• WO2008 / 030440 discloses a process comprising a first step of hydrogenating 1,2,3,3,3-pentafluoro-1-propene (1225ye) into 1, 1, 1, 2, 3-pentafluoropropane (245eb), which is then dehydrohalogenated to yield the desired product 2,3,3,3-tetrafluoro-1-propene (1234yf).
• the catalyst used in the dehydrohalogenation reaction is selected from the group consisting of aluminum fluoride; gamma alumina; fluorinated alumina; metal on alumina fluoride, - metal on fluorinated alumina; oxides, fluorides and oxyfluorides of magnesium, zinc and mixtures of magnesium and zinc and / or aluminum; lanthanum oxide and fluorinated lanthanum oxide; chromium oxides, chromium oxyfluorides, and cubic chromium trifluoride; carbon, acid-washed carbon, activated carbon, three-dimensional carbon materials; and metal compound supported on carbon; the metal being in the form of oxide, fluoride or oxyfluoride of at least one metal of the group consisting of sodium, potassium, rubidium, cesium, yttrium, lanthanum, cerium, praseodymium, neodymium, samarium, chromium, iron, cobalt , rhodium, nickel
• US-P-5396000 discloses the preparation of 1,1,1,2,3-pentafluoropropane by catalytic dehydrohalogenation of 1,1,1,2,3,3-hexafluoropropane (236ea) in
• the dehydrohalogenation catalyst is chromium III oxide or oxyfluoride, or carbon. Oxygen can be added to the stream of 1, 1, 1, 2, 3, 3-hexafluoropropane to maintain catalytic activity over time. The selectivities are high, but the conversion is not always very high.
• EP-A-974571 discloses a process for the dehydrofluorination of 1,1,1,3,3-pentafluoropropane to 1,1,1,3-tetrafluoro-2-propene.
• the invention thus provides a process for selective dehydrofluorination on a chromium-nickel mixed catalyst on an aluminum-based support.
• the mixed catalyst comprises an oxide, a halide or a chromium oxyhalide mixed with an oxide, a halide or a nickel oxyhalide, the mixed catalyst comprises a fluoride or a chromium oxyfluoride mixed with a fluoride or a nickel oxyfluoride.
• the aluminum-based support is an aluminum halide or oxyhalide.
• the aluminum-based support is a fluoride or an aluminum oxyfluoride.
• the catalyst comprises, by weight, from 0.5 to 20% of chromium and from 0.5 to 20% of nickel, these elements being present in a molar ratio between 0.5 and 5.
• the process is carried out in the gas phase, the process is carried out at a temperature of between 150 ° C.
• the process is carried out with a contact time of between 0 ° C. and 600 ° C. , 1 and 100 seconds, preferably between 1 and 50 seconds and advantageously between 2 and 20 seconds.
• the process is carried out in the presence of hydrogen, the molar ratio H 2/1, 1, 1, 2, 3-pentafluoropropane being between 0.3 and 30, especially between 0.5 and 20, preferably between 1 and 10.
• the invention further provides a use of a chromium-nickel mixed catalyst on an aluminum-based support as a selective dehydrofluorination reaction catalyst.
• the invention uses a mixed catalyst of chromium and nickel.
• This mixed catalyst contains both chromium and nickel.
• the molar ratio Cr: Ni, relative to the element metal, is generally between 0.5 and 5, for example between 0.7 and 2, especially close to 1.
• the catalyst may contain by weight from 0.5 to 20% of chromium and from 0.5 to 20% of nickel and, preferably, between 2 and 10% of each of the metals.
• the metal may be present in metallic form or in the form of derivatives, in particular oxide, halide or oxyhalide, these derivatives, in particular halide and oxyhalide, being obtained by activation of the catalytic metal.
• I 1 activation of the metal is not required, it is preferred.
• the support is based on aluminum.
• supports such as alumina, activated alumina or aluminum derivatives.
• aluminum derivatives are in particular aluminum halides or oxyhalides, for example described in US-P-4902838, or obtained by the activation method described below.
• the catalyst may comprise chromium and nickel in a non-activated form or in activated form on a support which has undergone as I 1 activation of metal or not.
• the catalyst can be prepared from alumina (generally so-called activated alumina, this activated alumina is a high porosity alumina, and is distinct from the alumina having undergone the metal activation treatment).
• the alumina is converted into aluminum fluoride or a mixture of aluminum fluoride and alumina, by fluorination with air and hydrofluoric acid, the conversion rate of the alumina in aluminum fluoride depending essentially on the temperature at which the fluorination of the alumina is carried out (generally between 200 0 C and 450 0 C, preferably between 250 0 C and 400 0 C).
• the support is then impregnated with aqueous solutions of chromium and nickel salts or with aqueous solutions of chromic acid, nickel salt and methanol (used as a chromium reducing agent).
• chromium and nickel salts it is possible to use chlorides, or other salts such as, for example, oxalates, formates, acetates, nitrates and sulphates or nickel dichromate, provided that these salts are soluble in the amount of water that may be absorbed by the support.
• the catalyst can also be prepared by direct impregnation of alumina (which in general is activated) using the solutions of the chromium and nickel compounds mentioned above. In this case, the transformation of at least a portion (for example 70% or more) of the alumina into aluminum fluoride or aluminum oxyfluoride takes place during the step of activating the metal of the catalyst.
• the activated aluminas that can be used for catalyst preparation are well known, commercially available products. They are generally prepared by calcining alumina hydrates (aluminum hydroxides) at a temperature of between 300 ° C. and 800 ° C.
• the aluminas (activated or not) may contain significant contents (up to 1000 ppm) of sodium without affecting the catalytic performance.
• the catalyst is conditioned or activated, that is to say transformed into active constituents and stable (at the reaction conditions) by a prior operation called activation.
• This treatment can be carried out either "in situ” (in the dehydrofluorination reactor) or in a suitable apparatus designed to withstand the conditions of activation.
• This activation step generally comprises the following steps:
• a drying step is carried out at high temperature (250 ° C. to 450 ° C., preferably 300 ° C. to 350 ° C.), generally under a stream of nitrogen or air.
• This step may be optionally preceded, in a first step, by a first drying step at low temperature (100 ° C. to 150 ° C., preferably 110 ° C. to 120 ° C.) in the presence of air or nitrogen.
• the duration of the drying step can be between 1 and 50 hours.
• a fluorination step This fluorination step is carried out at low temperature (180 ° C. to 350 ° C.) using a mixture of hydrofluoric acid and nitrogen, controlling the HF content so that the temperature does not exceed 350 ° C. 0 C. the duration of the fluorination step can be between 1 and 50 hours.
• a finishing step under current of pure hydrofluoric acid or diluted with nitrogen at a temperature up to 450 ° C.
• the duration of the finishing step may be between 1 and
• the catalytic precursors for example nickel and chromium halides, chromate or nickel dichromate, chromium oxide
• the catalytic precursors for example nickel and chromium halides, chromate or nickel dichromate, chromium oxide
• the catalytic precursors are converted into corresponding fluorides and / or oxyfluorides, resulting in a release of water and / or hydrochloric acid.
• the chemical analysis of the elements chromium, nickel, fluorine, aluminum, oxygen
• Such a catalyst is described in EP-A-486333, in particular page 3, lines 11-48, Examples IA, 2A and 4A, passages to which it is referred.
• This catalyst is used herein as a fluorination catalyst, in a catalytic fluorination reaction of chloro-1-trifluoro- 2,2,2-ethane (133a) with HF gas to yield tetrafluoro-1,1,1 2-ethane (134a).
• the dehydrofluorination reaction is the reaction in which HF is removed from a starting compound, leading to the creation of a double bond in the final compound.
• the reaction considered is selective, in that the starting compound
• the starting fluorocarbon compounds are in particular those comprising a terminal trifluoromethyl group.
• the dehydrofluorination reaction is generally carried out in the gas phase.
• the catalyst may be present in any suitable form, for example in the form of a fixed or fluidized bed, preferably in a fixed bed.
• the direction of flow can be from top to bottom or from bottom to top.
• the temperature may be between 150 ° C. and 600 ° C., preferably between 300 and 500 ° C. and advantageously between 300 and 400 ° C.
• the pressure may be atmospheric, or lower or higher, than this atmospheric pressure.
• the contact time (ratio between the volume of catalyst and the total flow of the charge) is generally between
• 0.1 and 100 seconds preferably between 1 and 50 seconds, in particular for 236ea and advantageously between 2 and 20 seconds, in particular for 245eb.
• a diluent gas nitrogen, helium or argon
• Hydrogen can also be injected, for example continuously, or discontinuously.
• the molar ratio H 2 / 245eb may vary within wide measures, including 'between 0.3 and
• the reaction is carried out in a reactor dedicated to reactions involving halogens.
• reactors are known to those skilled in the art, and may include interior coatings based for example on Hastelloy®, Inconel®, monel® or fluoropolymers.
• the reactor may also include heat exchange means, if necessary.
• the supply of reagents can in general be continuous, or can be stepped if necessary.
• reaction product in particular containing the desired 1234yf or 1225ye, HF and any by-products and unreacted starting materials, is separated in a conventional manner. Any unreacted reagents are advantageously recycled in the process.
• the conversion is more than 50%, preferably more than 70% and advantageously more than 80%.
• the selectivity is very high, in general of more than 80%, preferably more than 90% and advantageously more than 95%.
• the yield is generally greater than 80%.
• the conversion ratio is the% of the reacted starting material (mole number of reacted starting material / mole number of feedstock introduced);
• the desired product selectivity is the ratio of the number of moles of desired product formed to the number of moles of product that has reacted;
• the desired product yield is the ratio of the number of moles of desired product formed to the number of mole products introduced, the yield of the desired product can still be defined as the product of conversion and selectivity.
• the contact time is the inverse of the space velocity WH (or GHSV in English)
• the space velocity is the ratio between the total volumetric flow on the volume of the catalytic bed, under normal conditions of temperature and pressure.
• the catalyst used is a Ni-Cr / AlF 3 catalyst prepared as follows.
• a support obtained in a previous step are placed by fluorination of alumina.
• GRACE HSA fixed bed around 280 0 C with air and hydrofluoric acid (volume concentration of 5 to 10% of this acid in air).
• the starting GRACE HSA alumina has the following physicochemical characteristics: shape: beads 0.5-2 mm in diameter BET surface: 220 m 2 / g pore volume: 1.3 cm 3 / g
• 500 g of impregnated solid are loaded into a tubular reactor in inconel.
• the catalyst is first dried under nitrogen sweep at low temperature and then up to 320 0 C, at atmospheric pressure. It is then fluorinated in the presence of a hydrofluoric acid / nitrogen mixture (concentration by volume of 5 to 10% of this acid in nitrogen) at 320 ° C. and then up to 390 ° C.
• the feed of HF is then cut.
• the nitrogen sweep is maintained for 15 minutes at 390 ° C. and the catalyst is then cooled to 60 ° C. under a nitrogen sweep.
• the characteristics of the catalyst after activation are the following: BET surface: 40 m 2 / g - porous volume: 0.4 cm 3 / g chemical composition: Al: 25% "P: 58%” Cr: 5.3% "Ni: 6.4% Example 2. Dehydrofluorination of 245eb.
• a reactor with a volume of 25 cm 3 , containing 10 g of catalyst of Example 1 in the form of a fixed bed is used.
• the pressure is of an atmosphere.

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• 2008
  • 2008-03-28 FR FR0801729A patent/FR2929273B1/fr not_active Expired - Fee Related
• 2009
  • 2009-03-27 EP EP09724301.8A patent/EP2271605B1/fr active Active
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