Light-Enhanced Oxidative Adsorption Desulfurization of Diesel Fuel over TiO₂–ZrO₂ Mixed Oxides

This study explored a new method for the adsorptive desulfurization of liquid hydrocarbon fuels called “light-enhanced oxidative adsorption desulfurization (LEOADS)”, which combines the photo-oxidation of aromatic sulfur compounds with the adsorption of oxidized-sulfur compounds over an adsorbent. The LEOADS of dibenzothiophene in real diesel fuel (DBT/diesel) was conducted in a batch system under UV–vis irradiation at ambient conditions using air as an oxidant. The desulfurization performance of DBT decreased in the order of TiO₂–ZrO₂ ≫ TiO₂-CeO₂ > TiO₂ ≈ ZrO₂. Introducing simultaneous light irradiation together with an adsorption process using TiO₂–ZrO₂ can dramatically improve the sulfur uptake by 9-fold (5.2 mg-S/g-A) compared to one-step adsorptive desulfurization (0.6 mg-S/g-A) and by 1.4-fold compared to two-step photo-oxidative desulfurization (3.8 mg-S/g-A). Light and TiO₂–ZrO₂ play important roles in the LEOADS: Light enhanced peroxide generation and the TiO₂–ZrO₂ promoted the oxidation of DBT to DBTO₂ with the in situ generated peroxide. X-ray diffraction, UV–vis spectroscopy, N₂-adsorption desorption, and scanning electron microscopy techniques were used for the characterization of the materials.