1070-4272/04/7711-1847C2004 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 77, No. 11, 2004, pp. 1847!1853. Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 11,
2004, pp. 1865!1871.
Original Russian Text Copyright + 2004 by Pashkevich, Shelopin, Mukhortov, Petrov, Alekseev, Asovich.
AND POLYMERIC MATERIALS
Synthesis of Perfluoroalkanes by High-Temperature Reaction
of Graphite with Fluorine in a Fluidized Bed
D. S. Pashkevich, G. G. Shelopin, D. A. Mukhortov,
V. B. Petrov, Yu. I. Alekseev, and V. S. Asovich
Prikladnaya Khimiya Russian Scientific Center, St. Petersburg, Russia
Received July 23, 2004
Abstract-Synthesis of lower perfluoroalkanes (tetrafluoromethane, hexafluoroethane, octafluoropropane,
decafluorobutane) by high-temperature reaction of graphite with fluorine in a fluidized bed was studied.
Tetrafluoromethane, hexafluoroethane, octafluoro-
propane, and decafluorobutane are widely used in the
modern industry as ozone-friendly refrigerants, pro-
pellants, dielectrics, and gas-phase fluorine carriers for
semiconductor industry . The annual world con-
sumption of these substances reaches several thousand
tons; therefore, development of efficient processes for
their production is an urgent problem.
There exist several procedures for preparing these
compounds. Tetrafluoromethane is prepared from the
elements in the inverse wave of filtration combustion
of graphite in fluorine, using a fixed graphite bed .
The feasibility parameters of this process are high.
Hexafluoroethane can be prepared by catalytic fluo-
rination of fluorochloroethanes with HF . The raw
materials for these process destroy the ozone layer,
and their production should be stopped. The process
has also other drawbacks: large amount of hydrogen
chloride waste and the necessity of regeneration and
utilization of the environmentally hazardous chromi-
um magnesium fluoride catalyst.
Octafluoropropane is produced by fluorination of
hexafluoropropylene with cobalt trifluoride . The
production of hexafluoropropene also involves ozone-
decomposing substances . Furthermore, processes
involving cobalt trifluoride as fluorinating agent have
low productive capacity.
Decafluorobutane can be prepared by electrochem-
ical fluorination of tributylamine in an HF solution
. However, the yield and productive capacity of the
process are poor.
At the same time, it is known that all the above
perfluorocarbons and solid carbon polyfluoride (CF
are formed by high-temperature reaction of carbon
C(s) + F
(g) 6 (CF
(s) + CF
(g) + C
(g) + C
(g) +... (1)
The boiling points of tetrafluoromethane, hexafluo-
roethane, octafluoropropane, and decafluorobutane are
3128, 378, 337, and 32oC, respectively. In industrial
implementation of reaction (1), separation of the prod-
ucts by distillation seems to involve no serious prob-
lems. Thus, commercial mastering of carbon fluorina-
tion will allow several different processes to be com-
bined in a single process involving simple and cheap
raw materials, with an efficient distillation system.
Published data on the composition of gaseous prod-
ucts of carbon fluorination are contradictory. How-
ever, most of the authors indicate that the major
product is tetrafluoromethane. As an efficient process
for tetrafluoromethane production has been commer-
cially mastered , development of the process based
on carbon fluorination is appropriate only if higher
fluoroalkanes will be obtained in a yield comparable
with that of CF
Moissan was the first to perform the reaction of
carbon with fluorine ; he found that amorphous
carbon forms ignite in fluorine even at room temper-
ature, whereas graphite and diamond are resistant to
fluorine at normal temperature. Ruff reported in 1934
 that at 420oC graphite reacts with fluorine to form
a solid compound, carbon polyfluoride (C
also found that at 4603700oC the reaction occurs with
explosion, and at temperatures above 700oC graphite
burns in fluorine to form fluorocarbons, mainly tetra-