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PP-I-50GAS-PHASE HYDROFLUORINATION OF PERCHLOROETHYLENEINTO PENTAFLUOROETHANE: EXPERIMENT AND KINETICMODELINGReshetnikov S.I., Zirka A.A., Petrov R.V.Boreskov Institute of Catalysis SB RAS, Pr. Akademika Lavrentieva 5, Novosibirsk,630090, Russia, E-mail: reshet@catalysis.nsk.suUnder the Montreal Protocol On Substances That Deplete the Ozone Layer, themanufacture and consumption of ozone-depleting substances, such aschlorofluorocarbons, should be stopped within the next decade. This poses thechallenging problem of gaining more detailed insight into the synthesis ofnextgeneration, ethane-based Freons, such as pentafluoroethane (R-125). R-125 isobtained from perchloroethylene (PCE) in the presence of chromium-containingcatalysts on various supports. In particular, chromium–magnesium catalysts are usedfor this purpose [1–3].Here, we report the kinetics of PCE hydrofluorination into R-125 on a chromium–magnesium catalyst and discuss the reaction scheme taking into account formationof by-products.Kinetic regularities of the vapor-phase hydrofluorination of perchloroethylenewere studied at the total pressure of 0.4 MPa, temperature 330–390°C, contact time0.3–16 s and the molar ratio HF : PCE = 6–50.Based on the experimental data, the pathway of perchloroethylene fluorinationwith HF over a chromium-magnesium catalyst was identified. The process involvesseveral consecutive reactions for the formation of main fluorination products andparallel reactions for the formation of by-products. It was shown that the totalselectivity towards the main products decreases with the increase in temperature. Itindicates that activation energies for the formation of by-products are higher thanthose for the formation of main products. Kinetic constants and the activation energyof the PCE conversion was obtained on the assumption of the first order of thereaction rate. The PCE consumption rate under these conditions is satisfactorily describedby a first-order equation with respect to PCE.References[1]. US Patent 6165931, 2000.[2]. RF Patent 2179885, 2002.[3]. Zhul, Y., Fiedler, K., Rudiger, St., and Kemnitz, E., J. Catal., 2004, 219, 8.308