Adsorption and desorption of dibenzothiophene on Ag-titania studied by the complementary temperature-programmed XPS and ESR

Adsorption, desorption and structure of the surface chemical compounds formed upon interaction of dibenzothiophene (DBT) in solution of n-octane with the sulfur-selective Ag/Titania sorbent for the ultradeep desulfurization of liquid fuels was characterized by the temperature-programmed X-ray photoemission spectroscopy (XPS) and Electron Spin Resonance. Adsorption of DBT proceeds via chemisorption via the oxygen-containing surface groups. Desorption of DBT and thermal regeneration of the “spent” Ag/Titania were studied by the complementary temperature-programmed XPS and ESR from 25 °C to 525 °C, in the high vacuum vs. air. The XPS spectrum of the pure DBT is reported for the first time.

Research highlights▶ DBT chemisorbs from model fuel on TiO2 and Ag/TiO2 via O surface groups. ▶ DBT binds stronger to O sites of Ag/TiO2 that to these of TiO2. ▶ Adsorption complex “Ag/Titania + DBT” is stable under XPS conditions. ▶ XPS spectrum of pure DBT is reported for the first time. ▶ Adsorption complex undergoes desorption ∼175-325 °C and degradation ∼325-525 °C.