EFFECT OF CARBON SUPPORT AND MEAN PT PARTICLE-SIZE ON HYDROGEN CHEMISORPTION BY CARBON-SUPPORTED PT CATALYSTS

A series of carbon-supported platinum catalysts were prepared and characterized; the only variable during catalyst preparation was the support used. The influence of different carbon properties on the platinum dispersion is described. The results show that there is not a single carbon property that can be related to dispersion, each one playing a more or less important role. However, the surface area outside the micropores may control the Pt dispersion if the chemical nature of the support is kept constant and vice versa. The large range of platinum particle sizes used in this work-obtained from different carbon supports and sintering treatments-has allowed us to observe that a relationship between platinum particle size and weakly chemisorbed hydrogen exists. The uptake of this kind of hydrogen increases with particle size. © 1991.