Global and non-local coupling in oscillating heterogeneous catalytic reactions: The oxidation of CO on zeolite supported palladium

The role of global and non-local coupling involving mass and heat transfer in oscillating heterogeneous catalytic systems under normal pressure condit ions is studied for the oxidation of CO on zeolite supported palladium. Two catalysts with sufficiently different dynamic properties, i.e., different amplitudes and frequencies of the oscillations, were used in model experime nts of coupled oscillators in a reactor operated as a continuous stirred ta nk. Global coupling through the gas phase was identified to play the domina nt role in synchronizing a catalyst bed consisting of oscillators with diff erent properties. In addition, non-local coupling by diffusion within the p orous support has to be considered. Global coupling can also be achieved vi a heat transfer in the case of a support with high thermal conductivity.