METATHESIS OF 1-ALKENES IN THE LIQUID-PHASE OVER A RE2O7/GAMMA-AL2O3 CATALYST .2. KINETICS OF DEACTIVATION

The present study deals with the methodology for the optimal design of a catalytic reactor for the metathesis of alkenes over a deactivating Re2O7/gamma-Al2O3 catalyst. First of all the kinetics of the reaction, excluding deactivation, was modelled. It was shown that a model in which product desorption or interconversion of the alkene/carbene complex is rate-determining describes the experimental data best. This model was extended to include catalyst deactivation. Apparent activation energies of 22.5 kJ/mol and 12 kJ/mol were found for the metathesis of 1-octene and the deactivation reaction, respectively. Constant conversion in the reactor, despite deactivation, can be obtained by operating the reactor isothermally at equilibrium conversion or by means of temperature programming. These two modes of operation could be simulated with the model. Evaluation showed, that when the total amount of 1-octene converted per catalyst cycle is taken as the criterion, the temperature-programmed mode of operation is the one to be preferred.