(88b) Experimental Studies in the Characterization Occurring At the Catalytic Surfaces of Silver On Titania Adsorbents

Solid catalysts have been used in the transformation of hydrocarbons to useful products for many years. The majority of adsorbents/catalysts used consists of a non metallic support promoted by transition metallic oxides.  It has been well established that particle size and dispersion is directly related to the efficacy of adsorbents in heterogeneous catalysis. Thus, information on these two properties in particular is crucial to the development of adsorbents/catalyst with greater efficiency. Gaseous adsorption, XRD, and electron microscopy have been routinely applied in heterogeneous catalysis research for particle size determination.  This work will detail the use of XPS analysis in the investigation of Ag nanometer sized particles dispersed on TiO₂ support. XPS will be shown to be a more reliable technique for the small particle size determination than the traditional particle size estimation techniques. The limitations of the three techniques will be discussed in their application to particle size determination of Ag/TiO₂ adsorbents.  A correction factor will be introduced to chemisorption based on XPS analysis that will allow more accurate particle size determination.