Parameter estimation in a fixed-bed reactor operating under unsteady state: Oxychlorination of ethylene

During the oxychlorination of ethylene, the composition of the catalyst, cu pric chloride, is subject to change, and hence estimation of rate parameter s considering the unsteady-state situation is more reliable than assuming s teady state. In the present work, nonisothermal experimental data are colle cted in an unsteady-state fixed-bed reactor by changing the inlet temperatu re using a temperature-programmed preheater. The rate parameters are estima ted by developing an unsteady-state model which takes into account not only the reaction temperature and gas-phase conversions but also changes in the solid-phase composition in the catalyst, bed. The rate parameters estimate d in this study. are found to be different from the steady-state values rep orted in the literature. The disagreement in the rate parameters has been e xplained in terms of the properties associated with the solid phase. The mo st significant feature of this work is that the rate-temperature behavior,, calculated using the present rate constants, corresponds closely with that derived from independent catalyst composition studies reported in the lite rature, thus indirectly validating the parameters estimated in this work.