TRANSIENT KINETICS FROM THE TAP REACTOR SYSTEM - APPLICATION TO THE OXIDATION OF PROPYLENE TO ACROLEIN

Transient kinetic data have been extracted by use of the Temporal Analysis of Products (TAP) reactor system. In the TAP reactor high resolution transient pulse experiments are performed under vacuum conditions. A rigorous model is developed and applied to the determination of Knudsen diffusivities from experiments with inert pulses. The model was applied to the catalytic oxidation of propylene over an industrial multicomponent bismuth molybdate catalyst. By fitting simulated curves to the experimentally observed response curves, kinetic parameters for the different elementary steps of the reaction were determined. It was shown that the adsorption of propylene is practically irreversible at reaction temperature and that CO2 and acrylic acid are formed in consecutive reactions from propylene via acrolein. From the values for the kinetic parameters it is proven that under industrial conditions the adsorption of propylene is rate determining. The surface coverage under typical conditions is shown to be quite low. The kinetic model is successfully used for the simulation of a steady state reactor operating under industrial conditions. (C) 1995 Academic Press, Inc.