US2994723A - Manufacture of tetrafluoroethylene - Google Patents

Manufacture of tetrafluoroethylene Download PDF

Info

Publication number
US2994723A
US2994723A US828393A US82839359A US2994723A US 2994723 A US2994723 A US 2994723A US 828393 A US828393 A US 828393A US 82839359 A US82839359 A US 82839359A US 2994723 A US2994723 A US 2994723A
Authority
US
United States
Prior art keywords
water vapor
reaction
tetrafluoroethylene
temperature
mixture
Prior art date
Legal status (The legal status 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 status listed.)
Expired - Lifetime
Application number
US828393A
Other languages
English (en)
Inventor
Scherer Otto
Steimmetz Alfons
Kuhn Heinrich
Wetzel Walter
Grafen Karlheinz
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hoechst AG
Original Assignee
Hoechst AG
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
Application filed by Hoechst AG filed Critical Hoechst AG
Application granted granted Critical
Publication of US2994723A publication Critical patent/US2994723A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

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
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J19/0006—Controlling or regulating processes
    • B01J19/0013—Controlling the temperature of the process
    • 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
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00049—Controlling or regulating processes
    • B01J2219/00051—Controlling the temperature
    • B01J2219/00054—Controlling or regulating the heat exchange system
    • B01J2219/00056—Controlling or regulating the heat exchange system involving measured parameters
    • B01J2219/00058—Temperature measurement
    • B01J2219/00063—Temperature measurement of the reactants
    • 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
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00049—Controlling or regulating processes
    • B01J2219/00051—Controlling the temperature
    • B01J2219/00074—Controlling the temperature by indirect heating or cooling employing heat exchange fluids
    • B01J2219/00076—Controlling the temperature by indirect heating or cooling employing heat exchange fluids with heat exchange elements inside the reactor
    • B01J2219/00083—Coils
    • 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
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00049—Controlling or regulating processes
    • B01J2219/00051—Controlling the temperature
    • B01J2219/00157—Controlling the temperature by means of a burner
    • 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
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00049—Controlling or regulating processes
    • B01J2219/00051—Controlling the temperature
    • B01J2219/00159—Controlling the temperature controlling multiple zones along the direction of flow, e.g. pre-heating and after-cooling

Definitions

  • the reaction takes place with an increase in volume so that according to the principle of least constraint (Braun-Le Chatellier) the formation of tetrafluoroethylene is favored when the reaction is carried out under reduced pressure or in the presence of an inert gas, for example nitrogen or helium. It is known from the literature that by reducing the pressure to 0.5 atmosphere absolute the conversion of monochlorodifiuoromethane can be increased to 50% with a yield of tetrafiuoroethylene of about 90%.
  • the present invention is based on the unexpected observation that the monochlorodifiuoromethane conversion can be increased to about 65-70% with a 9094% yield of tetrafluoroethylene, calculated on the reacted monochlorodifiuoroethylene, by subjecting a mixture prepared from monochlorodifiuoromethane and, for example, 25 mol percent water vapor, to pyrolysis.
  • the monochlorodifluoromethane is not hydrolyzed by the water vapor at the relatively high temperatures employed, although it is known that halohydrocarbons containing fluorine are very sensitive to hydrolysis and that, more especially, monochlorodifiuoromethane not only undergoes pyrolysis with strongly diluted alkalies at room temperature, but also with water under conditions such as prevail in refrigerating apparatus (cf. Handbuch der K'ailtetechnik, volume IV, Die Kaltesch, Springer-Ver-lag, Berlin-Gottingen-Hei delberg, 1956, page 373, 345/48). 7
  • the proportion of water vapor in the starting mixture cannot, however, be increased at will at a given temperature and time of stay without the yield of tetrafiuoroethylene being reduced by splitting off of hydrogen fluoride; in other words the proportion of water vapor is not permitted to exceed a certain upper limit.
  • the process of this invention is carried out with the use of a reaction tube and the starting mixture contains Water vapor in a proportion of about 15-60 mol percent, preferably about 2030 mol percent, it is most advantageous to permit the starting mixture to stay in said reaction tube for a period of time of between about 0.05 and 0.8 second, preferably between about 0.1 and 0.4 second at a temperaure in the range of about 650 C. to 1,000 O, advantageously about 750 C. to 900 C. Under these conditions about 60-70% of the monochlorodifluoromethane used is converted and tetrafluoroethylene is obtained in a yield of about 94%, calculated on the mouochlorodifiuoromethane which underwent conversion.
  • the amount of heat necessary to produce the required reaction temperature can be supplied either by heating the mixture to undergo reaction by means of an appropriate heating device, or by heating the water vapor alone before it is mixed with the monochlorodifluoromethane to so high a temperature that, after the water vapor has been mixed with the monochlorodifluoromethane, the mixture obtained has the necessary reaction temperature.
  • the device comprises an inlet tube arranged concentrically within an enclosing tube which latter tube is surrounded by a jacket for heating the enclosing tube.
  • the reaction zone proper in this device has a slit-shaped cross-sectional area.
  • One wall of the reaction zone is heated while the opposing wall is cooled by the incoming gaseous starting material which is advantageously conducted in counter-current within and outside the reaction zone by means of a suitable device.
  • a suitable device i.e.
  • the water vapor is advantageously supplied by means of a dosing pump which transports the water to an evaption of the water vapor.
  • thermo-element It is also advantageous to preheat the gas to a temperature of about 350 C. to 600 C. by means of a preheater connected in series with the reaction device in order favorably to influence uniform temperature distribution in the reaction device.
  • This preheater may also be used to vaporize the water supplied by the dosing pump.
  • the temperature is advantageously measured with a thermo-element.
  • the reaction device provided with an annular slit may be lined with all the materials listed as being suitable in the aforesaid patent application, for example carbon, copper, copper-nickel alloys, silver, platinum, platinumiridium, platinum-rhodium or single or mixed sintered metal oxides, such as aluminum oxide, beryllium oxide or magnesium oxide or spinels, platinum being preferred.
  • the gases leaving the reactor are chilled in a cooler, "washed with water, dried, condensed and subjected to fractional distillation.
  • the oxyhydrogen flame burns in the cylindrical combustion chamber 1 which is conically tapered.
  • the mono chlorodifiuoromethane is supplied through inlet pipe 2, flows around reaction tube 3 which is concentrically surrounded by a jacket steel tube, and is sucked into said reaction tube 3 by the suction effect of the flame gases.
  • the temperature is measured by means of a thermo-element 4 at the inlet opening of the reaction tube, in other words at that place where the monochloro- 'difluoromethane comes into contact with the superheated water-vapor.
  • the lower end of reaction tube 3 around which water flows has a rubber connection to the steel tube.
  • the reaction products obtained are cooled to room temperature in the subsequent cooler 5.
  • the combustion chamber 1 is made of ceramic material, preferably quartz, and the reaction tube 3 is preferably made of highly sintered aluminum oxide shaped into a tube, or platinum.
  • the most favorable results are obtained using a mixture which contains a proportion of water vapor of between about 20 mol percent and 70 mol percent, preferably about 25 mol percent and 50 mol percent, and permitting said mixture to stay in the reaction tube for a period of time of between about 0.005 and 0.2 second, preferably about 0.01 and 0.1 second, at a temperature within the range of about 7004400 C., advantageously about 850 1100 C.
  • Example 1 reaction device as described in the aforesaid patent application, so that 7,655 grams per hour monochlorodifluoromethane were passed through the reaction device.
  • the inlet tube of the reaction device had a length of about 940 mm. and a diameter of 44 mm., and the jacket tube a diameter of 50 mm, so that the annular slit was 3 mm. wide.
  • the temperature was measured at the outside wall of the tube.
  • the medium time of stay of the gases in the reaction space was 0.2 second.
  • the products leaving the reaction device were chilled to about room temperature in a cooler with condensation and elimina- The hydrogen chloride split trap.
  • Example 2 In the reaction device shown in the accompanying drawing an oxyhydrogen flame was produced by introducing 23'0 liters/hour oxygen into 460 liters/hour hydrogen.
  • the water vapor-obtained had a temperature of 1400 C. at the inlet opening of the reaction tube.
  • the temperature was measured with the thermoelement 4.
  • the improvement which comprises pyrolyzing a gaseous mixture comprising difluoromonochloromethane and water vapor in a reaction zone having a cross-sectional area shaped as a slit, one side of said reaction zone being heated and its opposite side being cooled by the starting material which streams outside the reaction zone but along this opposite side, said water vapor being present in the gaseous starting mixture in an amount of about 15 to about 70 mole percent calculated upon the gaseous starting mixture.
  • reaction zone has a cross sectional area shaped as an endless slit.
  • a process for the manufacture of tetrafluoroethylene which comprises pyrolyzing a gaseous mixture consisting essentially of difluoromonochloromethane and water vapor in which the water vapor is contained in a proportion of between about 15 and about 70 mol percent calculated upon the gaseous mixture, at a temperature in the range of from about 650 C. to about 1400 C. within a period of about 0.005 to about 0.8 second.
  • a process for the manufacture of tetrafluoroethylene which comprises pyrolyzing a gaseous mixture consisting essentially of difluoromonochloromethane and water vapor in which the water vapor is contained in a proportion of between about 20 and about 40 mol percent calculated upon the gaseous mixture, at a temperature in the range from about 750 C. to about 1000 C. within a period of about 0.02 to about 0.4 second.
US828393A 1958-07-29 1959-07-20 Manufacture of tetrafluoroethylene Expired - Lifetime US2994723A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DEF0026279 1958-07-29

Publications (1)

Publication Number Publication Date
US2994723A true US2994723A (en) 1961-08-01

Family

ID=7091957

Family Applications (1)

Application Number Title Priority Date Filing Date
US828393A Expired - Lifetime US2994723A (en) 1958-07-29 1959-07-20 Manufacture of tetrafluoroethylene

Country Status (4)

Country Link
US (1) US2994723A (fr)
DE (1) DE1073475B (fr)
FR (1) FR1241770A (fr)
GB (1) GB904022A (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3284169A (en) * 1962-02-21 1966-11-08 Thiokol Chemical Corp Reactor equipment for the production of tetrafluoroethylene
US3306940A (en) * 1960-09-28 1967-02-28 Du Pont Process for the manufacture of perfluoroolefins
US3308174A (en) * 1962-01-24 1967-03-07 Ici Ltd Production of tetrafluoroethylene
US3338980A (en) * 1962-09-20 1967-08-29 Montedison Spa Process for the preparation of fluorolefines by pyrolysis
US3489807A (en) * 1968-02-09 1970-01-13 Haruo Shingu Process for the production of fluorinated olefinic compounds
US4849554A (en) * 1987-04-10 1989-07-18 Imperial Chemical Industries Plc Production of tetrafluoroethylene and hexafluoropropylene
EP2826766A4 (fr) * 2012-03-14 2015-09-16 Asahi Glass Co Ltd Procédé de production de 2,3,3,3-tétrafluoropropène

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3446858A (en) * 1963-03-30 1969-05-27 Daikin Ind Ltd Process for the manufacture of hexafluoropropene
US3354233A (en) * 1963-10-01 1967-11-21 Allied Chem Production of tetrafluoroethylene
KR100523561B1 (ko) * 2002-10-23 2005-10-25 한국과학기술연구원 테트라플루오로에틸렌과 헥사플루오로프로필렌의 동시제조방법

Citations (1)

* 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

Patent Citations (1)

* 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

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3306940A (en) * 1960-09-28 1967-02-28 Du Pont Process for the manufacture of perfluoroolefins
US3308174A (en) * 1962-01-24 1967-03-07 Ici Ltd Production of tetrafluoroethylene
US3284169A (en) * 1962-02-21 1966-11-08 Thiokol Chemical Corp Reactor equipment for the production of tetrafluoroethylene
US3338980A (en) * 1962-09-20 1967-08-29 Montedison Spa Process for the preparation of fluorolefines by pyrolysis
US3489807A (en) * 1968-02-09 1970-01-13 Haruo Shingu Process for the production of fluorinated olefinic compounds
US4849554A (en) * 1987-04-10 1989-07-18 Imperial Chemical Industries Plc Production of tetrafluoroethylene and hexafluoropropylene
EP2826766A4 (fr) * 2012-03-14 2015-09-16 Asahi Glass Co Ltd Procédé de production de 2,3,3,3-tétrafluoropropène

Also Published As

Publication number Publication date
FR1241770A (fr) 1960-09-23
GB904022A (en) 1962-08-22
DE1073475B (de) 1960-01-21

Similar Documents

Publication Publication Date Title
US4849554A (en) Production of tetrafluoroethylene and hexafluoropropylene
US2994723A (en) Manufacture of tetrafluoroethylene
US2758138A (en) Pyrolysis process for making perfluoropropene from tetrafluoroethylene
Fisher et al. Apparatus for the Preparation of Ketene by the Pyrolysis of Acetic Anhydride
Fawcett et al. Cyanogen fluoride: synthesis and properties
US3188356A (en) Method for producing vinylidene fluoride
US2614906A (en) In the method of making finely divided silica, the production of a combustible mixture comprising chloro silicon hydrides
US2617836A (en) Production of olefinic c4f8
GB902682A (en) Process for the manufacture of fluorethylenes
US4053529A (en) Process for the manufacture of vinylidene fluoride
Steunenberg et al. Pyrolysis of fluorocarbons1
US3308174A (en) Production of tetrafluoroethylene
JPS6157528A (ja) ハロアルカンの熱分解脱塩酸方法およびこれに使用する開始剤
US3894097A (en) Process for the preparation of hexafluoroisobutylene
US1677363A (en) Process of treating methane gas
US2759983A (en) Pyrolysis process for preparing hexafluoropropene from tetrafluoroethylene polymer
Buxton et al. 733. Organic fluorides. Part XIII. The high-temperature dimerisation of chlorotrifluoroethylene
US2395826A (en) Preparation of chlorofluorosilanes
US2992280A (en) Preparation of fluoroform
US2902521A (en) Process for the production of fluorocarbons
GB575672A (en) Improvements in and relating to methods of preparing tetrachloroethylene and chlorosilanes
US2811485A (en) Process for chlorinating dimethyl ether
US2725284A (en) Apparatus for reacting dense chlorinating vapor with a solid
US3158657A (en) Co-pyrolysis method for the preparation of fluoroaromatic compounds
US1315544A (en) Ration