Efficient oxidative desulfurization of model fuel by visible-light-driven MoS2-CeO2/SiO2-Al2O3 nano photocatalyst coating

Abstract

The MoS2-CeO2 nano photocatalyst on silica-alumina support was synthesized and dip- coated on glass plates with the aid of three polymeric surfactants, including polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA) and polyethylene glycol (PEG). The activity of resultant coatings was evaluated in photocatalytic oxidative desulfurization (ODS) of dibenzothiophene (DBT) and the results were compared with the activity of photocatalyst as powder. The MoS2-CeO2/SiO2-Al2O3 photocatalyst as powder degrades 96 % of DBT while immobilized photocatalyst coating (without surfactant) degraded 88 % of DBT. Using PVP, PVA, and PEG in MoS2-CeO2/SiO2-Al2O3 coating resulted in 86, 89, and 93 % of DBT conversion, respectively. Higher DBT removal by PEG containing coating compares to surfactant-free coating, was due to uniform morphology, more absorption of light, more shift of adsorption edge toward visible light, more surface OH groups, more porosity, more surface area, and bigger pore size, confirmed by FESEM, UV–vis DRS, BET-BJH, and FTIR. Beside PEG, silica sol was applied as a binder for MoS2-CeO2/SiO2-Al2O3 nano photocatalyst coating. The weight loss for this sample was insignificant after 30min of sonication, and none of the composing elements of coating was found in the fuel after five successive runs. With considering operating parameters like the number of photocatalyst coatings, the concentration of DBT, and pH, the DBT removal reached 98 %. Based on the obtained results, a mechanism was proposed for photocatalytic oxidative desulfurization of DBT using PEG containing MoS2-CeO2/SiO2-Al2O3 nano photocatalyst coating.