(662g) Characterization of Ag/TiO2 Adsorbents; Comparing and Contrasting Crystallite Size Using Oxygen Chemisorption and XPS Techniques

In the past several years, silver based sorbents have been investigated due to the desirable properties that these sorbents possess with respect to the desulfurization of logistic fuels. Particle size and dispersion are two crucial parameters determined from the chemistry occurring at the topmost atomic layers of the adsorbent. The surface characterization techniques: oxygen chemisorption and x-ray photoelectron spectroscopy (XPS) have proven to be useful in defining the Ag/TiO₂ adsorbent system. The use of oxygen chemisorption has detected nanometer scale occurrence while XPS showed sub-nanometer scale occurrence of Ag supported on titania. The discrepancy in the results from these two techniques can be attributed to the underlying perspectives and inherent assumptions intrinsic to each technique. In this study, the introduction of the multi-speciation behavior of Ag was proposed. This will account for both the reducible and irreducible behavior of Ag. This characterization will improve the accuracy of oxygen chemisorption to give a better representation of the real behavior occurring on the surface of the adsorbent.