USH1129H - Process for manufacture of 1,1,1,2-tetrafluoroethane - Google Patents
Process for manufacture of 1,1,1,2-tetrafluoroethane Download PDFInfo
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- USH1129H USH1129H US07/315,295 US31529589A USH1129H US H1129 H USH1129 H US H1129H US 31529589 A US31529589 A US 31529589A US H1129 H USH1129 H US H1129H
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- United States
- Prior art keywords
- chlorine
- trifluoroethane
- chloro
- catalyst
- hydrogen fluoride
- Prior art date
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- Abandoned
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- 238000004519 manufacturing process Methods 0.000 title claims abstract description 23
- 238000000034 method Methods 0.000 title claims abstract description 15
- 230000008569 process Effects 0.000 title claims abstract description 15
- LVGUZGTVOIAKKC-UHFFFAOYSA-N 1,1,1,2-tetrafluoroethane Chemical compound FCC(F)(F)F LVGUZGTVOIAKKC-UHFFFAOYSA-N 0.000 title claims abstract description 14
- 239000003054 catalyst Substances 0.000 claims abstract description 42
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims abstract description 27
- 229910000040 hydrogen fluoride Inorganic materials 0.000 claims abstract description 27
- CYXIKYKBLDZZNW-UHFFFAOYSA-N 2-Chloro-1,1,1-trifluoroethane Chemical compound FC(F)(F)CCl CYXIKYKBLDZZNW-UHFFFAOYSA-N 0.000 claims abstract description 25
- BFGKITSFLPAWGI-UHFFFAOYSA-N chromium(3+) Chemical compound [Cr+3] BFGKITSFLPAWGI-UHFFFAOYSA-N 0.000 claims abstract description 12
- 239000012808 vapor phase Substances 0.000 claims abstract description 7
- 239000000460 chlorine Substances 0.000 claims description 51
- 229910052801 chlorine Inorganic materials 0.000 claims description 27
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims description 22
- 239000000203 mixture Substances 0.000 claims description 15
- 230000006872 improvement Effects 0.000 claims description 3
- 238000006243 chemical reaction Methods 0.000 abstract description 29
- 230000000694 effects Effects 0.000 abstract description 11
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 abstract description 5
- 239000011651 chromium Substances 0.000 description 8
- 229910052736 halogen Inorganic materials 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 150000002367 halogens Chemical group 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- ZALMZWWJQXBYQA-UHFFFAOYSA-N [N].[Cl] Chemical compound [N].[Cl] ZALMZWWJQXBYQA-UHFFFAOYSA-N 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 4
- 229910052731 fluorine Inorganic materials 0.000 description 4
- 150000008282 halocarbons Chemical class 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 239000000376 reactant Substances 0.000 description 4
- -1 CHFClCHCl2 Chemical compound 0.000 description 3
- ZJULYDCRWUEPTK-UHFFFAOYSA-N dichloromethyl Chemical compound Cl[CH]Cl ZJULYDCRWUEPTK-UHFFFAOYSA-N 0.000 description 3
- 239000011737 fluorine Substances 0.000 description 3
- 239000011261 inert gas Substances 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 229910019830 Cr2 O3 Inorganic materials 0.000 description 2
- JNCMHMUGTWEVOZ-UHFFFAOYSA-N F[CH]F Chemical compound F[CH]F JNCMHMUGTWEVOZ-UHFFFAOYSA-N 0.000 description 2
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 229910052794 bromium Inorganic materials 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 150000001721 carbon Chemical group 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- 150000002222 fluorine compounds Chemical class 0.000 description 2
- 239000008188 pellet Substances 0.000 description 2
- 150000003254 radicals Chemical class 0.000 description 2
- 230000009257 reactivity Effects 0.000 description 2
- 229910021564 Chromium(III) fluoride Inorganic materials 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical class Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 1
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 229910001515 alkali metal fluoride Inorganic materials 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- GUNJVIDCYZYFGV-UHFFFAOYSA-K antimony trifluoride Chemical class F[Sb](F)F GUNJVIDCYZYFGV-UHFFFAOYSA-K 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 239000000571 coke Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000006704 dehydrohalogenation reaction Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000012025 fluorinating agent Substances 0.000 description 1
- 238000004817 gas chromatography Methods 0.000 description 1
- 239000008246 gaseous mixture Substances 0.000 description 1
- 150000004820 halides Chemical class 0.000 description 1
- 125000005843 halogen group Chemical group 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 235000011167 hydrochloric acid Nutrition 0.000 description 1
- 229910001026 inconel Inorganic materials 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- SCTINZGZNJKWBN-UHFFFAOYSA-M mercury(1+);fluoride Chemical class [Hg]F SCTINZGZNJKWBN-UHFFFAOYSA-M 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000003380 propellant Substances 0.000 description 1
- 238000000197 pyrolysis Methods 0.000 description 1
- 239000003507 refrigerant Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000005201 scrubbing Methods 0.000 description 1
- REYHXKZHIMGNSE-UHFFFAOYSA-M silver monofluoride Chemical class [F-].[Ag+] REYHXKZHIMGNSE-UHFFFAOYSA-M 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- FTBATIJJKIIOTP-UHFFFAOYSA-K trifluorochromium Chemical compound F[Cr](F)F FTBATIJJKIIOTP-UHFFFAOYSA-K 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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
Definitions
- This invention relates to an improved process for the manufacture of 1,1,1,2-tetrafluoroethane by the vapor-phase reaction of 2-chloro-1,1,1-trifluoroethane with hydrogen fluoride in the presence of inorganic chromium (III) catalysts.
- fluorinated hydrocarbons are generally prepared by a halogen exchange reaction of halocarbons, such as chlorohydrocarbons or bromohydrocarbons--most usually chlorohydrocarbons, with inorganic fluorine compounds such as alkali metal fluorides, antimony fluorides, silver fluorides and mercury fluorides or with hydrogen fluoride in the presence of a catalyst.
- halocarbons such as chlorohydrocarbons or bromohydrocarbons--most usually chlorohydrocarbons
- inorganic fluorine compounds such as alkali metal fluorides, antimony fluorides, silver fluorides and mercury fluorides or with hydrogen fluoride in the presence of a catalyst.
- the product stream contained 18.2% CF 3 CH 2 F, 80% unreacted CH 3 CH 2 Cl, 1.65% of a mixture of CF 3 CHF 2 and CF 3 CH 3 and 0.12% CF 2 ⁇ CHCl.
- What is not disclosed in the above-cited Bell patent is that in the reaction of CF 3 CH 2 Cl with HF in the presence of a Cr (III) catalyst at elevated temperatures, with time, the ability of the Cr (III) catalyst to catalyze the halogen exchange reaction is drastically reduced, such that the process becomes useless as an industrial process in a very short time.
- the catalyst may become completely inactive in a period of from about 150 to 300 hours.
- an object of the present invention to provide an improved process for manufacturing 1,1,1,2-tetrafluoroethane by the vapor phase reaction of 2-chloro-1,1,1-trifluoroethane with hydrogen fluoride in the presence of an inorganic chromium (III) catalyst. It is a further object of the present invention to provide a process for manufacturing 1,1,1,2-tetrafluoroethane by the vapor phase reaction of 2-chloro-1,1,1-trifluoroethane with hydrogen fluoride in the presence of an inorganic chromium (III) catalyst wherein the activity of the chromium (III) catalyst is maintained.
- 1,1,1,2-tetrafluoroethane which comprises contacting, in the vapor phase at elevated temperatures, a mixture of 2-chloro-1,1,1-trifluoroethane and hydrogen fluoride with an inorganic chromium (III) catalyst, the improvement comprising co-feeding an effective amount of molecular chlorine with said mixture of 2-chloro-1,1,1-trifluoroethane and hydrogen fluoride.
- the present improved process for preparing CF 3 CH 2 F involves co-feeding an effective amount of Cl 2 to the reactant stream of 2-chloro-1,1,1-trifluoroethane (CF 3 CH 2 Cl) and HF in the presence of an inorganic Cr (III) catalyst to maintain catalyst activity.
- halogen exchange reactions particularly when the catalyst used is an inorganic Cr (III) catalyst, would also benefit from the present improvement.
- Other halocarbons which may be used may be of the general formula CA 3 CH 2 X where A is Br, Cl or F and X is Cl or Br.
- Such halocarbons include, among others, CCl 3 CH 2 Cl, CFCl 2 CH 2 Cl, CF 2 ClCH 2 Cl, CCl 3 CH 2 Br, CFCl 2 CH 2 Br, CF 2 ClCH 2 Br, CF 3 CH 2 Br, CCl 2 BrCH 2 Br, CBr 2 ClCH 2 Cl, CHCl 2 CHCl 2 , CHFClCHCl 2 , CHF 2 CHCl 2 and the like. The latter three rearrange during the course of the reaction.
- the amount of hydrogen fluoride to be used in the present process depends upon the haloethane starting material.
- the molar ratio of hydrogen fluoride to haloethane should, in general, be at least equal to the number of halogen radicals of the haloethane to be replaced by fluorine radicals.
- the reactant haloethane is CF 3 CH 2 Cl
- at least one mol of HF per mol of CF 3 CH 2 Cl is generally used.
- an excess of HF may be used such that, with CF 3 CH 2 Cl as a reactant, the ratio of hydrogen fluoride to CF 3 CH 2 Cl is preferably from about 2:1 to about 15:1, more preferably in the range of from about 3:1 to about 10:1.
- the inorganic chromium (III) catalysts used in the present process are well known in the art and can be prepared in a variety of ways. Such chromium (III) catalysts may be in the form of oxides, halides, oxyhalides and the like. The chromium (III) catalysts may be activated, for example, by heating in the presence of steam, an inert atmosphere or in the presence of hydrogen fluoride.
- the chromium (III) catalyst may be used in any convenient form, such as compressed into pellets, used in a fixed bed or, when in appropriate particle size, as fluidized beds or used on supports, such as carbon, alumina and the like.
- Suitable temperatures for the present process are in the range of from about 300° C. to about 450° C., preferably in the range of from about 325° C. to about 400° C.
- Contact time may be in the range of from about 2 seconds to about 150 seconds, preferably from about 15 seconds to about 120 seconds.
- Atmospheric or superatmospheric pressures may be used, but superatmospheric pressures are preferred.
- the concentration of chlorine in a chlorine-inert gas mixture may be any convenient amount and is not critical so long as at least some amount is present.
- effective amount is meant an amount of chlorine in the co-feed which extends the period of catalyst activity beyond what it would be without the chlorine co-feed.
- the amount of chlorine in the co-feed is in the range of from about 0.01 to about 1 mol percent of the 2-chloro-1,1,1-trifluoroethane in the reactant feed stream, preferably in the range of from about 0.03 to about 0.08, more preferably in the range of from about 0.06 to about 0.08 mol percent of the CF 3 CH 2 Cl in the feed stream.
- the chlorine co-feed should begin almost immediately after the feeds of hydrogen fluoride and 2-chloro-1,1,1-trifluoroethane into the reactor are started and maintained continuously.
- Chlorine introduced into the reaction to prolong catalyst activity may be added as pure chlorine gas or may be introduced as gaseous mixtures with an inert gas such as nitrogen, depending upon the scale of the reaction.
- an inert gas such as nitrogen
- chlorine is preferably added as pure chlorine gas while on a smaller scale, the amount of chlorine introduced may be more readily controlled if a chlorine-inert gas mixture is used.
- 1,1,1,2-tetrafluoroethane (CF 3 CH 2 F) is useful as a refrigerant and as a propellant, particularly since it is not expected to play any role in stratospheric ozone depletion.
- the catalyst bed was first dried by passing nitrogen gas through the reactor tube while the tube was heated to 330° C. at about 12 psig. Then hydrogen fluoride was introduced to saturate the catalyst bed.
- a mixture of hydrogen fluoride and 2-chloro-1,1,1-trifluoroethane in a 3.8:1 molar ratio was fed to the catalyst bed.
- the contact time of this mixture with the catalyst was controlled by the feed rate at about 15 seconds.
- another feed of a chlorine-nitrogen mixture was started to provide about 0.3 mol % chlorine based on the 2-chloro-1,1,1-trifluoroethane feed.
- the production rate of 1,1,1,2-tetrafluoroethane was about 31 g per hour for 140 hours. Then the flow of chlorine-nitrogen was stopped, and almost immediately the production rate of 1,1,1,2-tetrafluoroethane began to drop such that, in the next 30 hours, the rate was about 21 g/hr or a drop in the production rate of about 32%.
- a feed of hydrogen fluoride/2-chloro-1,1,1-trifluoroethane was started at 330° C. and at about 160 psig to provide a contact time of about 112 seconds.
- the initial production rate of 1,1,1,2-tetrafluoroethane was 42 g/hr, but within 110 hours the production rate dropped to 3 g/hr or a drop in the production rate of almost 93%.
- Example 2 The equipment described in Example 1 was used.
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
An improved process is disclosed for the manufacture of 1,1,1,2-tetrafluoroethane by the vapor-phase reaction of 2-chloro-1,1,1-trifluoroethane with hydrogen fluoride in the presence of an inorganic chromium (III) catalyst which includes co-feeding molecular chlorine to extend catalyst activity.
Description
This invention relates to an improved process for the manufacture of 1,1,1,2-tetrafluoroethane by the vapor-phase reaction of 2-chloro-1,1,1-trifluoroethane with hydrogen fluoride in the presence of inorganic chromium (III) catalysts.
Industrially, fluorinated hydrocarbons are generally prepared by a halogen exchange reaction of halocarbons, such as chlorohydrocarbons or bromohydrocarbons--most usually chlorohydrocarbons, with inorganic fluorine compounds such as alkali metal fluorides, antimony fluorides, silver fluorides and mercury fluorides or with hydrogen fluoride in the presence of a catalyst.
As recognized in the art, the ease with which a halogen exchange reaction occurs depends primarily upon the particular manner in which the halogen atom to be exchanged for fluorine is attached to the carbon atom of the halocarbon. Thus, Hudlicky in Chemistry of Organic Fluoride Compounds, MacMillan Co., New York, NY (1962), pg. 98, points out the difficulty of converting the --CH2 Cl group to the --CH2 F group under various reaction conditions. Similarly, Sheppard and Sharts in Organic Fluorine Chemistry, W. A. Benjamin, Inc., New York, NY (1969), pp. 76-77, also teach that the Cl radical in the --CH2 Cl group is of very low reactivity and that, when reacted with fluorinating agents, rarely undergoes reaction to provide --CH2 F group.
Furthermore, it is known that fluoro-substitution on a carbon atom adjacent to the --CH2 Cl group reduces the reactivity of the Cl radical of the --CH2 Cl even more. Thus, with the above two unfavorable conditions, to prepare CF3 CH2 F by the vapor-phase reaction of CF3 CH2 Cl with HF requires rather drastic reaction conditions. Bell in U.S. Pat. No. 4,129,603 describes (column 3, lines 55-68) the reaction of CF3 CH2 Cl with HF with an HF to CF3 CH2 Cl ratio of 4:1, a reaction temperature of 350° C. and a contact time of 7 seconds continually over a period of 55 hours using a Cr2 O3 catalyst pretreated with HF. The product stream contained 18.2% CF3 CH2 F, 80% unreacted CH3 CH2 Cl, 1.65% of a mixture of CF3 CHF2 and CF3 CH3 and 0.12% CF2 ═CHCl. What is not disclosed in the above-cited Bell patent is that in the reaction of CF3 CH2 Cl with HF in the presence of a Cr (III) catalyst at elevated temperatures, with time, the ability of the Cr (III) catalyst to catalyze the halogen exchange reaction is drastically reduced, such that the process becomes useless as an industrial process in a very short time. Depending upon the reaction conditions, the catalyst may become completely inactive in a period of from about 150 to 300 hours.
It is reasonable to speculate that this drastic loss of catalyst activity is due to the rather high temperatures required to make this particular halogen exchange reaction proceed to a reasonable extent. Such elevated temperatures will increase dehydrohalogenation reactions, such as CF3 CH2 Cl to CF2 ═CHCl+HF, and even of the desired product, CF3 CH2 F to CF2 ═CHF+HF. These olefinic compounds can react, particularly on the catalyst surface, to form polymers, carbon or coke deposits which may make the catalyst surfaces unavailable for catalytic activity. Whatever the mechanism, in the reaction of CF3 CH2 Cl and HF over a Cr (III) catalyst at elevated temperatures, the catalyst will rapidly lose activity over a period of time; the higher the reaction temperature the faster will be the loss of activity.
Osaka et al. in British Patent 2,030,981 have recognized the above-discussed loss of activity of the chromium (III) catalyst in the halogen exchange reaction at high temperatures between CF3 CH2 Cl and HF. The patentees suggested introduction into the feed stream of from 0.002 to 0.05 mol O2 per mol of CF3 CH2 Cl to prolong the activity of the Cr (III) catalyst. While cofeeding of O2 with CF3 CH2 Cl prolongs the catalytic activity of Cr (III) catalysts, such modification cannot be used advantageously in an industrial process because of the additional problems it introduces. Among them are greatly increased formation of water in the reaction which increases the difficulty in isolating the desired product, and which greatly increases the corrosion in the condensed phase due to hydrofluoric and hydrochloric acids generated therefrom. Reaction of oxygen with various components of the reaction stream also introduces many undesirable oxygenated by-products.
It is, therefore, an object of the present invention to provide an improved process for manufacturing 1,1,1,2-tetrafluoroethane by the vapor phase reaction of 2-chloro-1,1,1-trifluoroethane with hydrogen fluoride in the presence of an inorganic chromium (III) catalyst. It is a further object of the present invention to provide a process for manufacturing 1,1,1,2-tetrafluoroethane by the vapor phase reaction of 2-chloro-1,1,1-trifluoroethane with hydrogen fluoride in the presence of an inorganic chromium (III) catalyst wherein the activity of the chromium (III) catalyst is maintained.
In a process for the manufacture of 1,1,1,2-tetrafluoroethane which comprises contacting, in the vapor phase at elevated temperatures, a mixture of 2-chloro-1,1,1-trifluoroethane and hydrogen fluoride with an inorganic chromium (III) catalyst, the improvement comprising co-feeding an effective amount of molecular chlorine with said mixture of 2-chloro-1,1,1-trifluoroethane and hydrogen fluoride.
The present improved process for preparing CF3 CH2 F involves co-feeding an effective amount of Cl2 to the reactant stream of 2-chloro-1,1,1-trifluoroethane (CF3 CH2 Cl) and HF in the presence of an inorganic Cr (III) catalyst to maintain catalyst activity.
While the present improved process is primarily applicable to the preparation of CF3 CH2 F from CF3 CH2 Cl, it is understood that other halogen exchange reactions, particularly when the catalyst used is an inorganic Cr (III) catalyst, would also benefit from the present improvement. Other halocarbons which may be used may be of the general formula CA3 CH2 X where A is Br, Cl or F and X is Cl or Br. Such halocarbons include, among others, CCl3 CH2 Cl, CFCl2 CH2 Cl, CF2 ClCH2 Cl, CCl3 CH2 Br, CFCl2 CH2 Br, CF2 ClCH2 Br, CF3 CH2 Br, CCl2 BrCH2 Br, CBr2 ClCH2 Cl, CHCl2 CHCl2, CHFClCHCl2, CHF2 CHCl2 and the like. The latter three rearrange during the course of the reaction.
The amount of hydrogen fluoride to be used in the present process depends upon the haloethane starting material. The molar ratio of hydrogen fluoride to haloethane should, in general, be at least equal to the number of halogen radicals of the haloethane to be replaced by fluorine radicals. Thus, when the reactant haloethane is CF3 CH2 Cl, at least one mol of HF per mol of CF3 CH2 Cl is generally used. However, in order to enhance the exchange reaction and to minimize the formation of side products, an excess of HF may be used such that, with CF3 CH2 Cl as a reactant, the ratio of hydrogen fluoride to CF3 CH2 Cl is preferably from about 2:1 to about 15:1, more preferably in the range of from about 3:1 to about 10:1.
The inorganic chromium (III) catalysts used in the present process are well known in the art and can be prepared in a variety of ways. Such chromium (III) catalysts may be in the form of oxides, halides, oxyhalides and the like. The chromium (III) catalysts may be activated, for example, by heating in the presence of steam, an inert atmosphere or in the presence of hydrogen fluoride. The chromium (III) catalyst may be used in any convenient form, such as compressed into pellets, used in a fixed bed or, when in appropriate particle size, as fluidized beds or used on supports, such as carbon, alumina and the like.
Suitable temperatures for the present process are in the range of from about 300° C. to about 450° C., preferably in the range of from about 325° C. to about 400° C.
Contact time may be in the range of from about 2 seconds to about 150 seconds, preferably from about 15 seconds to about 120 seconds.
Atmospheric or superatmospheric pressures may be used, but superatmospheric pressures are preferred.
The concentration of chlorine in a chlorine-inert gas mixture may be any convenient amount and is not critical so long as at least some amount is present. By effective amount is meant an amount of chlorine in the co-feed which extends the period of catalyst activity beyond what it would be without the chlorine co-feed. Generally the amount of chlorine in the co-feed is in the range of from about 0.01 to about 1 mol percent of the 2-chloro-1,1,1-trifluoroethane in the reactant feed stream, preferably in the range of from about 0.03 to about 0.08, more preferably in the range of from about 0.06 to about 0.08 mol percent of the CF3 CH2 Cl in the feed stream. For maximum effect, the chlorine co-feed should begin almost immediately after the feeds of hydrogen fluoride and 2-chloro-1,1,1-trifluoroethane into the reactor are started and maintained continuously.
Chlorine introduced into the reaction to prolong catalyst activity may be added as pure chlorine gas or may be introduced as gaseous mixtures with an inert gas such as nitrogen, depending upon the scale of the reaction. For large scale production, chlorine is preferably added as pure chlorine gas while on a smaller scale, the amount of chlorine introduced may be more readily controlled if a chlorine-inert gas mixture is used.
The desired product of the instant invention, 1,1,1,2-tetrafluoroethane (CF3 CH2 F) is useful as a refrigerant and as a propellant, particularly since it is not expected to play any role in stratospheric ozone depletion.
An Inconel schedule 40 U-tube reactor (1"×6') containing a thermocouple in the reaction zone was charged with about 900 ml of 20% CrF3 on activated carbon as 1/4" catalyst pellets. The U-tube was placed in a molten salt bath and connected to a feed system for feeding nitrogen, hydrogen fluoride, a mixture of hydrogen fluoride, 2-chloro-1,1,1-trifluoroethane and a 3.4% chlorine-in-nitrogen mixture. The exit from the U-tube was connected to a pressure control valve which was followed by a scrubbing system. The reaction product stream was analyzed by gas chromatography.
The catalyst bed was first dried by passing nitrogen gas through the reactor tube while the tube was heated to 330° C. at about 12 psig. Then hydrogen fluoride was introduced to saturate the catalyst bed.
A mixture of hydrogen fluoride and 2-chloro-1,1,1-trifluoroethane in a 3.8:1 molar ratio was fed to the catalyst bed. The contact time of this mixture with the catalyst was controlled by the feed rate at about 15 seconds. Very shortly after the feed of hydrogen fluoride and 2-chloro-1,1,1-trifluoroethane was started, another feed of a chlorine-nitrogen mixture was started to provide about 0.3 mol % chlorine based on the 2-chloro-1,1,1-trifluoroethane feed.
The production rate of 1,1,1,2-tetrafluoroethane was about 31 g per hour for 140 hours. Then the flow of chlorine-nitrogen was stopped, and almost immediately the production rate of 1,1,1,2-tetrafluoroethane began to drop such that, in the next 30 hours, the rate was about 21 g/hr or a drop in the production rate of about 32%.
Using the same equipment, catalyst and catalyst activation as described in Example 1, a feed of hydrogen fluoride/2-chloro-1,1,1-trifluoroethane was started at 330° C. and at about 160 psig to provide a contact time of about 112 seconds. The initial production rate of 1,1,1,2-tetrafluoroethane was 42 g/hr, but within 110 hours the production rate dropped to 3 g/hr or a drop in the production rate of almost 93%.
However, in a repeat of the above using a feed of hydrogen fluoride to 2-chloro-1,1,1-trifluoroethane of from 3.04 to 3.54 and chlorine-nitrogen co-feed to provide about 0.46 mol % chlorine, the production rate of 1,1,1,2-tetrafluoroethane remained at the level of 25-35 g/hr for 160 hours. Temporary interruption of the chlorine co-feed resulted in an immediate drop in the production rate. Resumption of chlorine co-feed maintained the production rate at about 20 g/hr for the next 90 hours. When the production rate dropped below 20 g/hr, the reaction temperature was incrementally raised over a 250-hour period to 395° C. to maintain the production rate at about 20 g/hr with chlorine co-feed.
The equipment described in Example 1 was used. The catalyst, used in about the same volume as in Example 1, was Cr2 O3 prepared by pyrolysis of (NH4)2 Cr2 O7.
After drying and hydrogen fluoride saturation of the catalyst, hydrogen fluoride and 1,1,1-trifluoro-2-chloroethane in about 11.3 molar ratio was fed into the reactor to provide a contact time of about 16 seconds with the catalyst bed at 350° C. and 12 psig pressure, and chlorine-nitrogen mixture was immediately started to provide about 1 mol % chlorine. Over a period of 315 hours, the production rate of 1,1,1,2-tetrafluoroethane was in the range of 8-15 g/hr.
Under the same conditions with this catalyst but without the chlorine co-feed, the production rate of 1,1,1,2-tetrafluoroethane would have decreased to about zero in 300 hours.
Claims (4)
1. In a process for the manufacture of 1,1,1,2-tetrafluoroethane which comprises contacting, in the vapor phase at elevated temperature, a mixture of hydrogen fluoride and 2-chloro-1,1,1-trifluoroethane with an inorganic chromium (III) catalyst, the improvement comprising co-feeding an effective amount of elemental chlorine with said mixture of hydrogen fluoride and 2-chloro-1,1,1-trifluoroethane.
2. The process of claim 1 wherein said temperature is from about 300° C. to about 450° C., said mixture of hydrogen fluoride and 1,1,1-trifluoro-2-chloroethane is in molar ratio of hydrogen fluoride to 2-chloro-1,1,1-trifluoroethane of from about 2:1 to about 15:1 and said chlorine co-fee is from about 0.01 to 1 mol % chlorine based on the amount of 2-chloro-1,1,1-trifluoroethane.
3. The process of claim 2 wherein said chlorine co-feed is from about 0.03 to about 0.08 mol % chlorine based on the said 2-chloro-1,1,1-trifluoroethane.
4. The process of claim 3 wherein said temperature is from about 325° C. to about 400° C., said mixture of hydrogen fluoride and 2-chloro-1,1,1-trifluoroethane is in molar ratio of hydrogen fluoride to 2-chloro-1,1,1-trifluoroethane of from about 3:1 to about 0.08 and said chlorine co-feed is from about 0.06 to about 0.08 mol % chlorine based on the said 2-chloro-1,1,1-trifluoroethane.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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US07/315,295 USH1129H (en) | 1989-02-24 | 1989-02-24 | Process for manufacture of 1,1,1,2-tetrafluoroethane |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US07/315,295 USH1129H (en) | 1989-02-24 | 1989-02-24 | Process for manufacture of 1,1,1,2-tetrafluoroethane |
Publications (1)
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USH1129H true USH1129H (en) | 1993-01-05 |
Family
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US07/315,295 Abandoned USH1129H (en) | 1989-02-24 | 1989-02-24 | Process for manufacture of 1,1,1,2-tetrafluoroethane |
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Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5705718A (en) * | 1993-10-13 | 1998-01-06 | Elf Atochem S.A. | Process for the purification of 1,1,1,2-tetrafluoroethane |
WO1998019981A1 (en) * | 1996-11-01 | 1998-05-14 | E.I. Du Pont De Nemours And Company | Manufacture of hexafluoroethane |
WO1999007470A1 (en) * | 1997-08-08 | 1999-02-18 | Alliedsignal Inc. | Fluorination catalysts and process for their preparation |
US5880049A (en) * | 1996-03-29 | 1999-03-09 | Elf Atochem S.A. | Regeneration of catalysts for gas phase fluorination |
US6242659B1 (en) | 1995-06-29 | 2001-06-05 | Elf Atochem, S.A. | Process for the manufacture of difluoromethane |
US20060036117A1 (en) * | 2004-08-10 | 2006-02-16 | Mitchel Cohn | Catalyst preparation processes, catalyst regeneration processes, halocarbon production processes, and halocarbon production systems |
US20090105510A1 (en) * | 2005-07-07 | 2009-04-23 | National Institute Of Advanced Industrial Science And Technology | Fluorination catalysts, method for their preparation, and method for producing fluorinated compounds using the catalysts |
-
1989
- 1989-02-24 US US07/315,295 patent/USH1129H/en not_active Abandoned
Non-Patent Citations (2)
Title |
---|
Hudlicky in Chemistry of Organic Fluoride Compounds, MacMillan Co., New York, NY (1962), p. 98. |
Sheppard and Sharts in Organic Fluorine Chemistry, W. A. Benjamin, Inc., New York, NY (1969), pp. 76-77. |
Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5705718A (en) * | 1993-10-13 | 1998-01-06 | Elf Atochem S.A. | Process for the purification of 1,1,1,2-tetrafluoroethane |
US6242659B1 (en) | 1995-06-29 | 2001-06-05 | Elf Atochem, S.A. | Process for the manufacture of difluoromethane |
US6639115B2 (en) | 1995-06-29 | 2003-10-28 | Atofina | Process for the manufacture of difluoromethane |
US5880049A (en) * | 1996-03-29 | 1999-03-09 | Elf Atochem S.A. | Regeneration of catalysts for gas phase fluorination |
WO1998019981A1 (en) * | 1996-11-01 | 1998-05-14 | E.I. Du Pont De Nemours And Company | Manufacture of hexafluoroethane |
WO1999007470A1 (en) * | 1997-08-08 | 1999-02-18 | Alliedsignal Inc. | Fluorination catalysts and process for their preparation |
US20060036117A1 (en) * | 2004-08-10 | 2006-02-16 | Mitchel Cohn | Catalyst preparation processes, catalyst regeneration processes, halocarbon production processes, and halocarbon production systems |
US20070282141A1 (en) * | 2004-08-10 | 2007-12-06 | Mitchel Cohn | Halocarbon production processes |
US20080058561A1 (en) * | 2004-08-10 | 2008-03-06 | Mitchel Cohn | Catalyst preparation processes, catalyst regeneration processes, halocarbon production processes, and halocarbon production systems |
US20090105510A1 (en) * | 2005-07-07 | 2009-04-23 | National Institute Of Advanced Industrial Science And Technology | Fluorination catalysts, method for their preparation, and method for producing fluorinated compounds using the catalysts |
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