Stabilization of supported Pd particles by the application of oxide coatings Original Research Article

The influence of an HfOx coating on the initial sintering rates of nearly monodisperse Pd model catalyst particles on silica was measured at well defined temperatures and residence times in the gas-phase.It was found that minute amounts of HfOx significantly retard the sintering of the Pd and at higher amounts the mean Pd size can even be maintained. Analysis of the Pd size distributions indicates an immobilization of the Pd particles and a growth by Ostwald ripening. The coated catalysts were extremely stable at reaction conditions and show only a negligible loss of activity in the hydrogenation of ethylene.