METHOD OF PREPARING PERFLUOROALKANE OF ETHANE OR PROPANE SERIES Russian patent published in 2000 - IPC

FIELD: preparation of perfluoroalkanes (coolants). SUBSTANCE: fluorochloroalkane is made to react with fluorine at elevated temperature in aluminium- containing catalyst bed. Stock is α-hydro-ω- chloroperfluoroalkane, preferably 1-hydro-2- chlorotetrafluoroethane (in pure form or in azeotropic admixture with octafluorocyclobutane) or 1-hydro-3- chlororhexafluoropropane. Process is carried out in two successive reaction zones. In first zone, use is made of aluminium oxide modified with fluoride of metal selected from group IB or VIII B, namely nickel or silver fluoride at 100-300 C and in second zone, with aluminium oxide modified with fluoride of metal selected from group IIIA or VA, more specifically with antimony or aluminium fluoride. Crystalline aluminium oxide has specific surface of 2-5 sq.m/g and contains 1-8 wt.% of metal fluoride. 1.4-1.8 moles of fluoride are fed per 1 mole of organic stock. EFFECT: increased yield (up to 93-97 %) of perfluoroalkanes. 12 cl, 13 ex, 3 tbl