Design and preparation of polyoxometalate-based catalyst [MIMPs]3PMo6W6O40 and its application in deep oxidative desulfurization with excellent recycle performance and low molar O/S ratio

A novel polyoxometalate-based ionic liquid salt 3-(1-methylimidazolium-3-yl) propane-1-sulfonate phosphomolybdenum tungsten ([MIMPs]3PMo6W6O40) was designed, prepared, and used as a catalyst in oxidative desulfurization (ODS). The catalyst was characterized by FT-IR, 1HNMR, XRD, XPS, TG-DTA, and Contact angle testing etc. The [MIMPs]3PMo6W6O40 shows high activity in dibenzothiophene (DBT) oxidative desulfurization, which can remove all the DBT in model oil with a low O/S molar ratio. The O/S molar ratio, reaction temperature, and different sulfur compounds were evaluated in detail. In addition, the catalyst still possesses high desulfurization efficiency in the presence of aromatic hydrocarbons. It is noteworthy that when the reaction temperature is 60 °C, the O/S molar ratio is 2.5, and the reaction time is 120 min, the catalyst exhibited excellent recycle lifetime of 33 times without significant decline of the activity. Furthermore, the content of sulfur compounds could also be reduced to 9 μg/g in real diesel.