XPS SIMS STUDY ON THE SURFACE-CHEMISTRY OF COMMERCIALLY AVAILABLE ACTIVATED CARBONS USED AS CATALYST SUPPORTS

The specific surface properties of activated carbons used as support materials for precious metal catalysts were investigated by XPS and SIMS. The surface C/O ratios and changes in the spectrum of surface-functional groups after different chemical pretreatments were measured. A correlation between the differences in graphitic/aromatic and aliphatic carbon contributions and of hydrogen present on the carbonaceous surfaces and the corresponding XPS and SIMS signals has been observed. The influence of natural impurities of activated carbons on the catalytic activity of powdered-type catalysts and the effect of surface carbides on the precious metal dispersion on pelletized shell-type catalysts are presented. The information gives a better understanding of the interdependence between the surface chemistry of the activated carbon and the performance of the catalysts. © 1992.