THE EFFECT OF MO ON THE CATALYTIC AND SURFACE-PROPERTIES OF RH-MO ZRO2 CATALYSTS/

A series of Rh-Mo/ZrO2 catalysts with fixed Rh and different Mo loadin gs were prepared and characterized by H-2 chemisorption, XRD, TPR, TEM and XPS. The catalysts were studied in two reactions: the hydrogenati on of carbon monoxide and the hydrogenation of toluene. The results su ggest that the increase in the Mo content produces a partial coverage of the support and the Rh particles. Moreover, at high Mo coverage, an increase of the MoO3 layer thickness is produced. After being treated in hydrogen, the molybdenum oxide remains as slightly reduced particl es, while Rh is essentially as Rh-0, with only a small contribution of Rh+ species. The Mo promotes the formation of oxygenates in the CO hy drogenation and it does not affect the activity in the hydrogenation o f toluene.