SILCs in oxidative desulfurization: effect of support and heteropolyanion

Hybrid imidazolium SILCs (supported ionic liquid catalysts) were prepared on the basis of H3PMo12O40 and H3PW12O40, grafted to mesoporous silicas of two types: silica gel and silochrome. They are active and stable catalysts for the peroxide oxidation of thiophene and thioanisole and oxidative desulfurization of diesel fuel. The structure of heteropolyanions on the surface depends on the silica nature and the Im: HPA ratio; a decrease in this ratio leads to their partial destruction. The specific activity (TOF) for the conversion of thiophene, which is the most oxidation-resistant sulfur-containing heterocycle, was 80–100 h−1 for W derivatives and 40–47 h−1 for Mo derivatives, which exceeds the values known from the literature. The use of W catalysts reduces the sulfur content in diesel fuel from 1080 to 7–8 ppm.