Preparation, characterization and application of platinum catalysts immobilized on clays
Clay-supported platinum catalysts were prepared by ion-exchange using cationic clays. The immobilized platinum cations were reduced by applying liquid- or gas-phase reduction procedures. The catalysts obtained were examined by X-ray diffractometry, and the results were compared with the diffractograms of the parent clays and that of a catalyst prepared by impregnation. The modifications in the diffractograms were used to estimate the fraction of metal migrated from the interlamellar space on the outer surface of the clay lamellae. The reaction rates and selectivities obtained in the hydrogenation of cinnamaldehyde and crotonaldehyde over these catalysts supported our interpretation related to the position of the metal particles.