Preparation of core–shell PW12@TiO2 microspheres and oxidative desulfurization performance

Abstract

A polyoxometalate-based microsphere catalyst has been prepared through the one-step template method using phosphotungstic acid as the core and TiO₂ as the shell, denoted as PW₁₂@TiO₂. Multiple characterisation methods namely FT-IR, XRD, XPS, Raman, SEM and TEM were used to characterize the resultant materials, and results indicate that the phosphotungstic acid was encapsulated into the TiO₂ phase as the core to form the core–shell structure. The resultant composites were used as catalysts for the oxidative desulfurization of a model oil with H₂O₂ as oxidant and acetonitrile as solvent. Catalyst PW₁₂@TiO₂ exhibited good catalytic activity, with 99.9% S-removal of dibenzothiophene after 60 min under the optimum conditions. Leaching and recycling experiments revealed that the PW₁₂@TiO₂ catalyst has excellent recyclability, and there was no significant decrease in S-removal after seven cycles under identical reaction conditions, which could be attributed to the fabrication of the core–shell structure, thus inhibiting the loss in the active sites.