(689d) Regeneration Studies of Ag/TiO2 Sorbent with Thiophene Derivatives for Sulfur Removal

Ag/TiO₂ based adsorbents have been found to selectively remove thiophenes derivates and their alkylated derivates from high sulfur jet fuels. These sulfur containing heterocyclic hydrocarbons are difficult to remove from traditional HDS reactors. Ag/TiO₂ has a capacity to remove 6-7 mg S/g of sulfur aromatics from JP5 fuel in the presence of 160 fold excess of competing aromatics. Ag/TiO₂ is regenerable in air for multiple cycles. In this study, the mechanism for thermal regeneration was investigated using Temperature Programmed Desorption / Temperature Programmed Reaction Spectroscopy. TPD/TPRS showed the desorption profiles of chemical reactions of the adsorbed S-containing species with the Ag/TiO₂. SO₂ and H₂S were desorbed from two dominant peaks center at varying temperatures depending on the thiophene derivative. Further characterization of surface sulfur species was done by XPS; which did not confirm the presence surface sulfates SO₄^2- or sulfites SO₃^2-. The optimum regeneration temperature was found to be 673 K. A well defined model system was employed to isolate the steps and verify qualitatively the concepts of the system. It is desired to regenerate the sorbent in approximately 20 minutes in air.