(560dd) Process Modified UV Assisted TiO2 Adsorptive Desulfurization Mechanism Study

One-time UV pretreatment on commercial Anatase TiO₂ has been proven effective in enhancing the sulfur heterocycle specificity and saturation capacity of TiO₂ sorbents for over two weeks. Previous efforts in our laboratory have shown the increased densities of surface hydroxyl are the key factors for this enhancement effect. The current study provides further evidence of the previous assertion by tracking the UV-induced conversion of adsorbed water and lattice oxygen into surface hydroxyls as monitored by XPS. Two different commercial TiO₂ adsorbents (@163 and 70 m²/g) were investigated at various hydration levels as determined by TGA. The deconvolution details from photoelectron peaks demonstrated both the qualitative nature and quantitative conversion of one adsorbed water and one lattice oxygen into two surface hydroxyls. Eight different reaction cases were examined using the 163 and 70 m²/g sorbents at 4 different hydration levels each. The measured stoichiometry for the above noted conversion varied from 1.83 to 2.15 with an average value of 1.98 and a standard deviation of 0.10. Samples removed from the XPS UHV chamber and stored in laboratory conditions showed that UV-generated surface hydroxyls can persist for over 2 weeks with or without handling.