Studies of surface and structural heterogeneity of carbon supports and carbon-supported catalysts
Activated carbons are generally used as support materials for precious metal catalysts. Properties of carbon that are important to catalyst preparation and application include composition, surface area, microstructure and pore shape and size distribution. Macropores (> 50 nm), mesopores (2-50 nm) and micropores (<2 nm) generally coexist in activated carbons. The accessibility of metal particles dispersed in microporous systems is of predominant importance, especially for large molecules that exhibit slow diffusion transport in narrow pores. It is desirable to have metal particles highly dispersed in readily accessible locations. As part of an on-going program of the characterization of carbonsupported catalysts we report some preliminary observations of the microstructure of carbon supports by a variety of electron microscopy techniquesCommercial carbon supports and carbon-supported Pt catalysts were used in this study. High resolution secondary electron (SE) microscopy, low voltage backscattered electron (LVBE) microscopy and high-angle annular dark-field (HAADF) microscopy techniques were employed to extract surface and structural information.