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WO1993024224A1 - Traitement de catalyseurs d'hydrogenation - Google Patents

Traitement de catalyseurs d'hydrogenation Download PDF

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Publication number
WO1993024224A1
WO1993024224A1 PCT/GB1993/001020 GB9301020W WO9324224A1 WO 1993024224 A1 WO1993024224 A1 WO 1993024224A1 GB 9301020 W GB9301020 W GB 9301020W WO 9324224 A1 WO9324224 A1 WO 9324224A1
Authority
WO
WIPO (PCT)
Prior art keywords
catalyst
oxygen
oxidising agent
hydrogenation
atmosphere
Prior art date
Application number
PCT/GB1993/001020
Other languages
English (en)
Inventor
Samuel David Jackson
Jenny O'kell
Peter Paul Clayton
Original Assignee
Imperial Chemical Industries Plc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB929211272A external-priority patent/GB9211272D0/en
Priority claimed from GB939301746A external-priority patent/GB9301746D0/en
Application filed by Imperial Chemical Industries Plc filed Critical Imperial Chemical Industries Plc
Publication of WO1993024224A1 publication Critical patent/WO1993024224A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C17/00—Preparation of halogenated hydrocarbons
    • C07C17/23—Preparation of halogenated hydrocarbons by dehalogenation
    • 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
    • B01J23/90—Regeneration or reactivation
    • B01J23/96—Regeneration or reactivation of catalysts comprising metals, oxides or hydroxides of the noble metals
    • 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
    • B01J38/00—Regeneration or reactivation of catalysts, in general
    • B01J38/04—Gas or vapour treating; Treating by using liquids vaporisable upon contacting spent catalyst
    • B01J38/12—Treating with free oxygen-containing gas
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C17/00—Preparation of halogenated hydrocarbons
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/584—Recycling of catalysts

Definitions

  • This invention relates to a process for the treatment of hydrogenation catalysts, in particular carbon supported hydrogenation catalysts which are useful, for example, in the hydrogenolysis (the replacement of halogen by hydrogen in saturated molecules) of chlorofluorocarbons and hydrochlorofluorocarbons and in the hydrogenation (addition of hydrogen across ethylenic double-bonds ) of halogenated hydrocarbons, (hereafter referred to collectively as "hydrogenation”) .
  • Hydrogenation catalysts are used, for example, in the hydrogenation of dichlorodifluoromethane and chlorodifluoromethane and in the hydrogenation of dichlorotetrafluoroethane and chlorotetrafluoroethane .
  • chlorofluorocarbons which are used on a large scale around the world, may be damaging the earth's protective ozone layer and there is now in place international agreement to ensure that their manufacture and use is restricted and eventually completely phased out.
  • Chlorofluorocarbons are used, for example, as refrigerants, as foam blowing agents, as cleaning solvents and as propellents for aerosol sprays in which the variety of applications is virtually unlimited. Consequently, much effort is being devoted to finding suitable replacements for chlorofluorocarbons which will perform satisfactorily in the many applications in which chlorofluorocarbons are used but which will not have the aforementioned damaging effect on the ozone layer.
  • Hydrofluorocarbons such as difluoromethane , also known as HFA 32, and 1 , 1 , 1 , 2-tetrafluoroethane , also known as HFA 134a, are of interest as replacements, in particular as replacements in refrigeration, air-conditioning and other applications.
  • a process for the treatment of a hydrogenation catalyst which comprises contacting the catalyst with an atmosphere comprising an oxygen-containing oxidising agent at elevated temperature .
  • the temperature should be at least 100°C, usually at least 150°C.
  • a hydrogenation catalyst obtainable by a process comprising contacting the catalyst with an atmosphere comprising an oxidising agent at elevated temperature .
  • the catalyst may be one which has been previously employed and consequently deactivated in a hydrogenation reaction, usually a vapour phase hydrogenation reaction, and particularly the hydrogenation of a halo (hydro ) fluorocarbon.
  • Hydrogenation catalysts are well known, and a variety have been proposed. Such catalysts typically comprise a Group Villa metal, for example nickel, rhodium, iridium, ruthenium, osmium, cobalt, palladium and platinum. Other metals have also been proposed, for example rhenium.
  • the preferred catalyst depends upon the particular hydrogenation reaction in which it is being employed but in general a particularly preferred catalyst comprises palladium. Such preferred catalysts may comprise only palladium or may comprise palladium and other metals which may be present as alloys with the palladium or as mixtures of metals.
  • the metal catalyst is typically carried on a suitable support, for example alumina, fluorinated alumina, silica, silicon carbide or carbon, in particular an active carbon. Any and all of these hydrogenation catalysts, particularly supported metal catalysts may be beneficially treated according to the present invention.
  • the process of the invention has particular utility for the treatment of carbon supported metal catalysts, the ( re )activation of which has hitherto :.aused particular difficulty due to the need to balance ( re )activation of the catalyst with avoiding destruction of the carbon support.
  • carbon supported metal catalysts may be ( re )activated with an oxygen-containing oxidising agent, without destruction of the carbon support, even at elevated temperatures at which burning of the carbon support would be expected .
  • a commonly employed and widely available carbon supported metal hydrogenation catalyst comprises palladium carried on an active carbon support.
  • a typical method involves impregnating the support with an aqueous solution of the salt of the metal, for example a halide, and thereafter drying the catalyst.
  • an "atmosphere comprising an oxidising agent” there is meant a gaseous composition which comprises an oxygen-containing oxidising agent, for example oxygen itself or a gaseous oxide, for example a gaseous oxide of nitrogen, especially nitrous oxide, N2O.
  • an oxygen-containing oxidising agent for example oxygen itself or a gaseous oxide, for example a gaseous oxide of nitrogen, especially nitrous oxide, N2O.
  • the atmosphere may also comprise other gaseous matter, for example the atmosphere may also comprise an inert diluent or other species which may in fact improve the performance of the treatment process.
  • the atmosphere may also comprise nitrogen, hydrogen and/or hydrogen chloride. we particularly prefer that the atmosphere comprises nitrogen in addition to the oxygen containing oxidising agent. It may also be beneficial to employ hydrogen chloride in combination with the oxygen-containing oxidising agent.
  • the composition of the atmosphere may vary over a wide range, the optimum composition in any particular application being dependent upon the particular catalyst being treated, it's degree of deactivation and the particular oxygen-containing oxidising agent and temperature employed.
  • the atmosphere will usually comprise at least 12 by volume, preferably at least 52 by volume, and more preferably at least 10Z by volume of the oxygen-containing oxidising agent.
  • the catalyst comprises palladium supported on an active carbon and the oxygen-containing oxidising agent comprises oxygen i * elf
  • the atmosphere comprises at least 15Z by volume of oxygen
  • the oxygen-containing oxidising agent comprises nitrous oxide
  • the atmosphere comprises at least 202 by volume of nitrous oxide, more preferably at least 302 by volume and especially at least 502 by volume.
  • Particularly preferred oxygen containing oxidising agents are oxygen and nitrous oxide, especially oxygen, and a particularly preferred atmosphere is air which may be diluted with, for example, nitrogen so as to dilute the oxygen.
  • oxygen-containing oxidising agent in particular oxygen or nitrous oxide depends upon the particular catalyst being treated, and in particular the specific metal and support being employed. Whilst the efficiency of the treatment process with any particular oxygen-containing oxidising agent may vary from one catalyst combination of metal and support to another, the skilled man may determine by routine trial and error the optimum oxygen containing oxidising agent and conditions to employ with any particular catalyst.
  • the catalyst may be purged with nitrogen both prior to and after the treatment with the atmosphere comprising an oxygen-containing oxidising agent in order to avoid the formation of any explosive mixtures of hydrogen and oxygen-containing oxidising agent.
  • the conditions under which the catalyst is purged with nitrogen are conveniently the same as those under which the catalyst treatment process is carried out.
  • the temperature at which the process is effected is also dependent upon the particular catalyst being treated and it's degree of deactivation although in general we prefer that the temperature is at least 250°C. There is generally no benefit in using a temperature greater than about 400°C. Preferred temperatures depend upon the choice of oxygen- containing oxidising agent and the amount thereof present in the atmosphere. Where the oxygen-containing oxidising agent is oxygen itself or nitrous oxide, the temperature is preferably in the range from about 250°C to about 350°C. Where the catalyst comprises a carbon supported metal, in particular palladium supported upon an active carbon and the oxygen-containing oxidising agent is oxygen or nitrous oxide, the temperature is more preferably in the range from about 275°C to about 325°C.
  • the process is conveniently carried out at about atmospheric pressure, although superatmospheric or subatmospheric pressures may be employed if desired.
  • the flow rate of the atmosphere comprising an oxidising agent may be within a wide range depending to some extent upon the volume of the catalyst being treated. Typically, the flow rate will be in the range from about 0.001 to about 100 times, preferably from about 0.1 to about 10 times, the bed volume of the catalyst being treated per minute.
  • the preferred (re )activation time between the catalyst and the atmosphere comprising the oxidising agent that is the time for which the catalyst is exposed to the atmosphere, is dependent upon the composition of the atmosphere, the degree of any deactivation of the catalyst and the temperature and pressure at which the process is carried out.
  • the ( re )activation time will be in the range from a few minutes, say 1 to 5 minutes to a few days, say 2 to 3 days, and is typically in the range from about 10 minutes to about 2 days.
  • the ( re )activation time is preferably in the range from about 5 minutes to about 24 hours, whereas where the oxygen containing oxidising agent is nitrous oxide, the ( re )activation time is preferably in the range from about 10 minutes to about 2 hours.
  • the catalyst which has been treated according to the invention is particularly useful in the hydrogenolysis /hydrogenation of halofluorocarbons and halohydrofluorocarbons .
  • a process for the production of hydrohalofluorocarbons and/or hydrofluorocarbons which comprises contacting a halofluorocarbon or hydrohalofluorocarbon with hydrogen at elevated temperature in the presence of a hydrogenation catalyst which has been treated with an atmosphere comprising an oxygen-containing oxidising agent at elevated temperature.
  • halofluorocarbons and hydrohalofluorocarbons used as starting materials comprise at least one atom of chlorine or bromine and generally will be chlorofluorocarbons or hydrochlorofluorocarbons .
  • the chlorofluorocarbon or hydrochlorofluorocarbon will typically comprise 1, 2 or 3 carbon atoms although it may comprise more than 3, say up to 6, carbon atoms.
  • the (hydro )halofluorocarbon may be unsaturated or saturated, cyclic or acyclic and straight chain or branched chain, although the (hydro )halofluorocarbon will usually be a straight chain saturated acyclic compound, that is a linear (hydro )halofluoroalkane .
  • Particularly useful hydrogenation reactions in which a hydrogenation catalyst according to the invention may be employed include (a) the hydrogenation of a haloethane, in particular a chloroethane , having 4 fluorine atoms, for example 1,1-dichlorotetrafluoroethane, 1,2-dichlorotetrafluoroethane and chlorotetrafluoroethane to chlorotetrafluoroethane and/or tetrafluoroethane , in particular 1 ,1 , 1 , 2-tetrafluoroethane ; and (b) the hydrogenation of a compound of formula CF2 where X and Y are independently Cl, Br or H (but not both H) , to difluoromethane.
  • 300 ml of the deactivated catalyst (as example 1) was divided into 6 x 50 ml batches.
  • the procedure described below was carried out with a 50ml batch of the catalyst except that the temperature of regeneration in each example was as stated in Table 2.
  • the 50ml batch was charged to a 1" diameter
  • Inconel reactor enclosed in a furnace.
  • the activity of this deactivated catalyst was measured by passing 120ml /minute hydrogen and 60 ml/minute chlorodifluoromethane over the catalyst at a temperature of 300°C and atmospheric pressure
  • the deactivated catalyst (as example 1) was charged to a 1/2" diameter Inconel pressure microreactor enclosed in a furnace.
  • the activity of this deactivated catalyst was measured by passing 230ml /minute hydrogen and 115 ml/minute chlorodifluoromethane over the catalyst at a temperature of 300°C and 7.5 barg pressure (standard "tivity test conditions) .
  • the reactor off-gases were npled and the samples analysed by gas i. romatography .
  • Example 9 30ml of a fresh catalyst comprising 102 palladium supported on Norit RX3 extrudate active carbon was divided into two 15ml samples.
  • a first sample (example 9) was treated with air under the conditions of example 8.
  • the results are shown in Table 4, and demonstrate the beneficial effect of air treatment on the activity of the fresh catalyst.
  • the 15ml batch was charged to a 1/2" diameter Inconel reactor enclosed in a furnace. Air was passed over the catalyst at a flow rate of 25ml/minute, atmospheric pressure and the temperature stated in Table 5 for 16 hours. After this time the air was switched off and the activity of the catalyst monitored under the standard activity test conditions of example 8 ( 230ml /minute hydrogen, 115ml/minute chlorodifluoromethane , 300°C and 7.5 barg pressure. The results are shown in Table 5.
  • a deactivated catalyst (as example 1) was charged to a 1" diameter Inconel reactor tube enclosed in a furnace and the activity of the catalyst was measured by passing 90ml/minute hydrogen and 30ml/minute of a mixture of 1,1,1,2-tetrachlorodifluoroethane and
  • Example 17 The procedure of example 17 was repeated except that the catalyst was a fresh catalyst comprising 52 Pd carried on Grade 208c active carbon (supplied by Sutcliffe Speakman Ltd). The results are shown in Table 7.
  • the catalyst comprised 112 by weight palladium carried on a Grade 208c active carbon support (active carbon supplied by Sutcliffe Speakman Ltd), reactions were carried out in a 1 inch internal diameter Inconel tubular reactor and the oxygen-containing oxidising agent was Nitrous oxide .
  • the activity of a 30 ml sample of fresh catalyst in the hydrogenation of chlorodifluoromethane to difluoromethane was determined by charging the sample of catalyst to the reactor and feeding a gaseous mixture of 50ml/min hydrogen and 25ml/minute chlorodifluoromethane over the catalyst at 292°C.
  • the composition of the off-gas was determined by Gas Chromatograhy and the results are shown in Table 8.
  • the catalyst was then aged at about 300°C by prolonged exposure to the hydrogen and chlorodifluoromethane gaseous mixture described above until the activity of the catalyst fell below 152 conversion of chlorodifluoromethane .
  • the activity of e aged catalyst is also given in Table 9.
  • the aged catalyst was treated by passing nitrous oxide at 30ml/minute over the catalyst at 305°C for increasing time increments and its activity was determined after each time increment by passing a

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

Abstract

L'invention concerne un procédé de traitement d'un catalyseur d'hydrogénation, plus particulièrement un catalyseur métallique à support carbone. Ledit procédé consiste à mettre le catalyseur en contact avec une atmosphère comprenant un agent d'oxydation contenant de l'oxygène, en particulier de l'oxygène ou de l'oxyde azoté. L'invention se rapporte également à un procédé de production d'hydrohalofluorocarbones et/ou d'hydrofluorocarbones qui consiste à mettre un halofluorocarbone ou un hydrohalofluorocarbone avec de l'hydrogène, à une température élevée, en présence d'un catalyseur d'hydrogénation préalablement traité avec une atmosphère comprenant un agent d'oxydation contenant de l'oxygène. Le catalyseur peut être un catalyseur neuf ou ayant été désactivé après avoir été utilisé dans l'hydrogènolyse d'un halofluorocarbone ou d'un hydrohalofluorocarbone.
PCT/GB1993/001020 1992-05-28 1993-05-19 Traitement de catalyseurs d'hydrogenation WO1993024224A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GB929211272A GB9211272D0 (en) 1992-05-28 1992-05-28 Treatment of catalysts
GB9211272.1 1992-05-28
GB9301746.5 1993-01-29
GB939301746A GB9301746D0 (en) 1993-01-29 1993-01-29 Treatment of hydrogenation catalysts

Publications (1)

Publication Number Publication Date
WO1993024224A1 true WO1993024224A1 (fr) 1993-12-09

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1993/001020 WO1993024224A1 (fr) 1992-05-28 1993-05-19 Traitement de catalyseurs d'hydrogenation

Country Status (1)

Country Link
WO (1) WO1993024224A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5679876A (en) * 1995-05-10 1997-10-21 Elf Atochem S.A. Purification of pentafluoroethane

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2028202A1 (de) * 1969-06-10 1970-12-17 Atlantic Richfield Company, New York, N.Y, (V.St,A.) Verfahren zur Regenerierung von Katalysatoren
FR2061890A5 (en) * 1969-10-01 1971-06-25 Inst Kataliza Sibirs Palladium oxide catalysed hydrogenation ofsulpholene
US4346019A (en) * 1981-06-22 1982-08-24 Air Products And Chemicals, Inc. Stabilization and regeneration of activated carbon supported palladium chloride catalysts in the oxidation of vinyl halides
EP0212602A1 (fr) * 1985-08-29 1987-03-04 Bayer Ag Procédé de régénération de catalyseurs pour la réduction en phase gazeuse de composés nitrés aromatiques
EP0258137A1 (fr) * 1986-08-25 1988-03-02 Institut Français du Pétrole Procédé de régénération d'un catalyseur d'hydroconversion d'hydrocarbures
WO1991017824A1 (fr) * 1990-05-22 1991-11-28 E.I. Du Pont De Nemours And Company Activation de catalyseurs de metaux precieux destines a l'hydrodeshalogenation des hydrocarbures substitues par halogene et contenant du fluor et au moins un autre halogene

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2028202A1 (de) * 1969-06-10 1970-12-17 Atlantic Richfield Company, New York, N.Y, (V.St,A.) Verfahren zur Regenerierung von Katalysatoren
FR2061890A5 (en) * 1969-10-01 1971-06-25 Inst Kataliza Sibirs Palladium oxide catalysed hydrogenation ofsulpholene
US4346019A (en) * 1981-06-22 1982-08-24 Air Products And Chemicals, Inc. Stabilization and regeneration of activated carbon supported palladium chloride catalysts in the oxidation of vinyl halides
EP0212602A1 (fr) * 1985-08-29 1987-03-04 Bayer Ag Procédé de régénération de catalyseurs pour la réduction en phase gazeuse de composés nitrés aromatiques
EP0258137A1 (fr) * 1986-08-25 1988-03-02 Institut Français du Pétrole Procédé de régénération d'un catalyseur d'hydroconversion d'hydrocarbures
WO1991017824A1 (fr) * 1990-05-22 1991-11-28 E.I. Du Pont De Nemours And Company Activation de catalyseurs de metaux precieux destines a l'hydrodeshalogenation des hydrocarbures substitues par halogene et contenant du fluor et au moins un autre halogene

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5679876A (en) * 1995-05-10 1997-10-21 Elf Atochem S.A. Purification of pentafluoroethane

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