Kinetic study of the gas-phase hydrofluorination of tetrachloroethylene into pentafluoroethane over a Cr-Mg catalyst

The influence of the tetrachloroethylene (TCE) hydrofluorination reaction conditions (temperature and residence time) on the activity of the Cr-Mg catalyst and pentafluoroethane selectivity has been experimentally studied. It has been established that the process proceeds via a complex parallel-consecutive mechanism that includes, along with hydrogen fluoride (HF) molecule addition at the double bond and consecutive substitution of fluorine for chlorine, the disproportionation reaction resulting in the formation of by-products. A kinetic model of the process has been proposed and its parameters, such as rate constants and activation energies, have been determined. The model allows predicting the composition of the target and intermediate products and by-products in wide ranges of residence times and reaction temperatures (300–400°C).