Tungsten based catalysts for oxidative desulfurization: surface species and partially reduced systems as key features to improve the activity

Abstract

Tungsten oxide based catalysts for the oxidative desulfurization (ODS) process of dibenzothiophene compounds using H₂O₂ as oxidizing agent were studied. Catalysts were characterized by TPR-H₂, SEM-EDS, XRD, N₂-physisorption and Raman spectroscopy. Different surface tungsten oxide species were detected and related to the ODS activity, furthermore, the predominance of the surface tungsten oxide species was associated with the tungsten loading. Moreover, in some catalysts, WO₃ crystals were detected and their role in the performance of the catalysts was studied too. Finally, the catalysts were partially reduced and tested in the ODS reaction, the reduced catalysts exhibited high activity and an improvement of H₂O₂ to sulfones yield.