US3183277A - Process for the manufacture of fluorethylenes - Google Patents

Process for the manufacture of fluorethylenes Download PDF

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Publication number
US3183277A
US3183277A US94864A US9486461A US3183277A US 3183277 A US3183277 A US 3183277A US 94864 A US94864 A US 94864A US 9486461 A US9486461 A US 9486461A US 3183277 A US3183277 A US 3183277A
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Prior art keywords
reaction
tube
reaction zone
slit
gas
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Expired - Lifetime
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US94864A
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English (en)
Inventor
Scherer Otto
Steinmetz Alfons
Kuhn Heinrich
Grafen Karlheinz
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Hoechst AG
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Hoechst AG
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    • 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
    • C07C17/263—Preparation of halogenated hydrocarbons by reactions involving an increase in the number of carbon atoms in the skeleton by condensation reactions
    • C07C17/269—Preparation of halogenated hydrocarbons by reactions involving an increase in the number of carbon atoms in the skeleton by condensation reactions of only 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
    • B01J12/00—Chemical processes in general for reacting gaseous media with gaseous media; Apparatus specially adapted therefor
    • B01J12/005—Chemical processes in general for reacting gaseous media with gaseous media; Apparatus specially adapted therefor carried out at high temperatures, e.g. by pyrolysis
    • 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
    • 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

Definitions

  • tetrafiuorethylene by heating difluoromonochloromethane at a high temperature for a short time. For example, by passing difluorochloromethane at the rate of 180 grams per hour at 650 C. to 800 C. through a tube having a diameter of 8 mm. and a length of 700 mm., and which is open at both ends, tetrafiuorethylene is obtained at a conversion of 25 to 30 percent by weight calculated on the starting material used and in a yield of 90 percent by weight calculated on the starting material that undergoes reaction.
  • the tube used in the aforesaid pyrolysis process is made of graphite, silver or platinum.
  • the decrease in yield that occurs when the internal diameter of the tube exceeds a certain value, which is 7 within the range of about 20 to 30 mm., can be explained by the fact that, due to the altered conditions of flow, temperature distribution is not uniform within the reaction gas.
  • the favorable conditions necessary for heating all the molecules of the reaction gas as uniformly as possible cannot be ensured in a tube of large diameter, because the surface of the tube available for heating be comes too small relative to the volume of the tube, which increases with the diameter, and therefore, also, relative to the quantity of gas to be reacted.
  • the unsatisfactory conduction of heat is increased when the smooth tube is packed with fillers which divert the mixture in a direction perpendicular to the direction of flow, i.e. complicate dilfusion to the heated wall.
  • apparatus for the manufacture of chloride-containing fluor- 3,183,277 Patented May 11, 1955 ethylenes which comprises a tube having an internal diameter of 18 mm., heated over a length of cm.
  • the tube is packed, preferably with glass balls, and is provided with a central shaft into which thermo-elements are placed. It has been stated that 0.4 mol of substance can be passed per hour through that apparatus.
  • a comparison of the last-mentioned apparatus with the above-mentioned smooth tube which has an internal diameter of 8 mm. and through which about 2 mols of substance can be passed per hour clearly shows that the yield which may be obtained with the tube having an internal diameter of 18 mm. is considerably decreased in spite of the larger diameter and that the apparatus is consequently completely unsuitable for use in processes in which larger quantities, for example, quantities that are a hundred times the above-mentioned quantity, are to be passed through per unit of time.
  • the slitshaped cross-sectional area may be rectangular, elliptical or of another form; it may be partly or completely limited by straight lines, circles or other curved or bent lines and may in particular he recurrent in itself, that is to say endless, for example, have an annular form, all this provided that, according to the term slit, one dimension of the cross-sectional area is visibly greater than the other.
  • the proportion of the length to the width of the slit shall at least be 2:1 and is advantageously within the range of 10:1 to 1000:1. Greater proportions, for example, proportions of 10,000:l or 100,00021, are still suitable but the preparation of such slits is more difficult.
  • the endless slit may be defined geometrically (see the accompanying drawings) as follows:
  • the cross-sectional area of the reaction chamber is bounded by two lines recurrent in themselves, which do not intersecteach other and the distance between which is advantageously not more than 18 mm. and not less than 1.5 mm.
  • the radius of curvature of the boundary lines may be infinitely great in parts of the lines, and the boundary lines may partly be parallel.
  • the reaction chamber should have a length that is such that the time of sojourn in the heated reaction chamber is within the range of 0.01 to 2 seconds and preferably within the range of 0.1 to 0.8 second.
  • the splitting off of hydrogen halide having a higher molecular weight than hydrogen fluoride can be brought about at temperatures within the range of 500 to 1100 C., advantageously 650 to 800 C.
  • an inlet tube a is arranged concentrically within an enclosing tube b, which latter tube is surrounded by a jacket for heating the tube b.
  • the gas used as starting material is passed into the tube a and is deflected at the inner end of this tube so as to flow in the opposite direction through the reaction zone d between the inner tube a and the outer tube b.
  • Reaction zone a which has a slit-shaped cross-sectional area, is bounded by the external surface of the tube a and the internal surface of the tube 17.
  • the stream of gas flowing through the reaction zone is heated on the outside by the wall of the tube b and is cooled on the inside by the wall of the inlet tube a through which the gas is introduced, the tube b being heated by a heating element and the inner wall of the tube a being cooled by the incoming gas.
  • the cross-sectional area of the reaction zone d may have various forms, for example, it may be circular, elliptical or rectangular (see FIGURE 3), so that the reaction zone surrounds the inlet tube a like a ring, that is to say, the slit-shaped cross-sectional area of the zone is closed upon itself and endless.
  • the reaction zone may be arranged only on one side of the gas inlet tube. This form of apparatus is shown in FIGURES 4 and 5, and is especially suitable for carrying out the process of the invention on a large industrial scale, because of the space.
  • the considerably higher area outputs of tetrafiuorethylene obtained by the pyrolysis of difluoromonochloromethane at temperatures within the range of 650 C. to 900 C., and preferably 700 C. to 850 C., is illustrated by the fact that about 0.09 gram of tetrafluorethylene is obtained per hour per square centimeter of surface of a known reaction tube having a diameter of 8 mm., whereas about 0.82 gram of tetrafluorethylene is obtained per hour per square centimeter of surface of reaction tube in the process of the invention. In the latter case the area output is therefore about 900 percent greater.
  • the rate of output of the desired product in the process of the invention can be increased to any desired extent by enlarging the dimensions of the apparatus without reducing the quantity of starting material that undergoes conversion or the yield obtained.
  • An important advantage of the process of the invention is that very good conversions of starting material and yields are obtained without the use of a catalyst.
  • the process of the invention may be carried out in the presence of a catalytically active non-metal, metal, metal alloy or compound, for example, carbon, copper, a copper-nickel alloy, platinum, platinum-iridium, platinum-rhodium or single or mixed sintered metal oxides, such as aluminum oxide, beryllium oxide or magnesium oxide or spinels.
  • the catalyst may be disposed in the reaction zone in various ways.
  • the walls of the reaction zone may consist of the catalytic material or of silver or they may be lined therewith.
  • Metals or metal .alloys may be present in the reaction zone, for example, in the form of wire or wire netting. Particularly good yields of fluor-ethylenes can be obtained by carrying out the reaction in the presence of platinum or a platinum alloy.
  • Example 3 288 grams (1.7 mols) of 1,1-difluoro-1,2,2-trich1orethane were passed at 550 C. in the course of 1 hour through the reaction apparatus described in Example 1 (see FIGURES 1 and 2 of the accompanying drawings). From the quantity of hydrogen chloride that had been split off, which was determined by titration, it was found that 92 percent of the starting material had undergone conversion. The yield was percent calculated on the 1,1-difluoro-1,2,2-trichlorethane that underwent reaction.
  • 1,1-difluoro-1- chloroethane is pyrolyzed at a temperature of from 650 to 900 C. to form 1,1-difluoroethylene.
  • reaction zone is bounded by at least two opposing walls, one of which is heated and the other of which is cooled.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
US94864A 1958-02-06 1961-03-10 Process for the manufacture of fluorethylenes Expired - Lifetime US3183277A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DEF0024987 1958-02-06

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US (1) US3183277A (fr)
DE (1) DE1068695B (fr)
FR (1) FR1216649A (fr)
GB (1) GB902682A (fr)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4351805A (en) * 1981-04-06 1982-09-28 International Business Machines Corporation Single gas flow elevated pressure reactor
US4721575A (en) * 1986-04-03 1988-01-26 Vertech Treatment Systems, Inc. Method and apparatus for controlled chemical reactions
US4869833A (en) * 1986-04-03 1989-09-26 Vertech Treatment Systems, Inc. Method and apparatus for controlled chemical reactions
US5024818A (en) * 1990-10-09 1991-06-18 General Motors Corporation Apparatus for forming carbon fibers
US5413773A (en) * 1990-10-09 1995-05-09 General Motors Corporation Method for forming carbon filters
WO2002006193A3 (fr) * 2000-07-14 2002-07-25 Du Pont Synthese d'olefines perfluorees
FR2937033A1 (fr) * 2008-10-13 2010-04-16 Arkema France Procede de preparation de fluorure de vinylidene.
US20150368169A1 (en) * 2007-07-06 2015-12-24 Honeywell International Inc. Preparation of fluorinated olefins via catalytic dehydrohalogenation of halogenated hydrocarbons

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1068695B (de) * 1958-02-06 1959-11-12 Farbwerke Hoechst Aktiengesellschaft vormals Meister Lucius 6. Brüning, Frankfurt/M Verfahren zur Herstellung von Fluoräthylenen
BE627531A (fr) * 1962-01-24
US3337645A (en) * 1963-04-05 1967-08-22 Mobil Oil Corp Catalytic conversion of fluorocarbons
SK285692B6 (sk) * 2002-11-26 2007-06-07 Novácke Chemické Závody, Akciová Spoločnosť Zariadenie tvaru dvoch súosových stojatých valcovpre podmienky chemických technológií a spôsob jeho využitia

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2551573A (en) * 1945-11-30 1951-05-08 Du Pont Pyrolysis of chloro-fluoro alkanes
US2566807A (en) * 1947-04-23 1951-09-04 American Cyanamid Co Method of preparing chlorofluoroethylenes
US2763532A (en) * 1950-12-18 1956-09-18 Union Oil Co Process for hydrogen cyanide production
FR1216649A (fr) * 1958-02-06 1960-04-26 Hoechst Ag Procédé de préparation d'éthylènes fluorés

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2551573A (en) * 1945-11-30 1951-05-08 Du Pont Pyrolysis of chloro-fluoro alkanes
US2566807A (en) * 1947-04-23 1951-09-04 American Cyanamid Co Method of preparing chlorofluoroethylenes
US2763532A (en) * 1950-12-18 1956-09-18 Union Oil Co Process for hydrogen cyanide production
FR1216649A (fr) * 1958-02-06 1960-04-26 Hoechst Ag Procédé de préparation d'éthylènes fluorés

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4351805A (en) * 1981-04-06 1982-09-28 International Business Machines Corporation Single gas flow elevated pressure reactor
US4721575A (en) * 1986-04-03 1988-01-26 Vertech Treatment Systems, Inc. Method and apparatus for controlled chemical reactions
US4869833A (en) * 1986-04-03 1989-09-26 Vertech Treatment Systems, Inc. Method and apparatus for controlled chemical reactions
US5024818A (en) * 1990-10-09 1991-06-18 General Motors Corporation Apparatus for forming carbon fibers
US5413773A (en) * 1990-10-09 1995-05-09 General Motors Corporation Method for forming carbon filters
WO2002006193A3 (fr) * 2000-07-14 2002-07-25 Du Pont Synthese d'olefines perfluorees
US7271301B2 (en) 2000-07-14 2007-09-18 E.I. Du Pont De Nemours And Company Synthesis of perfluoroolefins
US20150368169A1 (en) * 2007-07-06 2015-12-24 Honeywell International Inc. Preparation of fluorinated olefins via catalytic dehydrohalogenation of halogenated hydrocarbons
US10807925B2 (en) * 2007-07-06 2020-10-20 Honeywell International Inc. Preparation of fluorinated olefins via catalytic dehydrohalogenation of halogenated hydrocarbons
FR2937033A1 (fr) * 2008-10-13 2010-04-16 Arkema France Procede de preparation de fluorure de vinylidene.
WO2010043792A1 (fr) * 2008-10-13 2010-04-22 Arkema France Procede de preparation de fluorure de vinylidene
US8350101B2 (en) 2008-10-13 2013-01-08 Arkema France Method for preparing vinylidene fluoride

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Publication number Publication date
GB902682A (en) 1962-08-09
FR1216649A (fr) 1960-04-26
DE1068695B (de) 1959-11-12

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