Ultrafast Oxidative Desulfurization of Diesel Fuel Catalyzed by a Polyoxometalate-Based Catalyst Immobilized on Functionalized Y-SBA-15.

Y-SBA-15 was synthesized by doping yttrium (Y) into SBA-15 using a solvent-free solid-state grinding method, and 1-butyl-3-methylimidazolium phosphomolybdic salt ([Bmim]3PMo12O40, abbreviated as [Bmim]PMoO) was also synthesized. [Bmim]PMoO/Y-SBA-15 was prepared and used for oxidative desulfurization (ODS). The physicochemical characteristics of the catalyst have been characterized by FT-IR, XRD, N2 adsorption-desorption, FESEM, TEM, XPS, contact angle testing, EPR, etc. A lipophilic surface is beneficial for making the catalyst well disperse in an oil phase, and a hydrophilic core can help to store aqueous oxidants. Therefore, the amphiphilic catalyst 25[Bmim]PMoO/10Y-SBA-15 exhibited high catalytic activity in dibenzothiophene (DBT) ODS, and sulfur compounds can be removed completely within 40 min under the following conditions: VOil = 10 mL, mcatalyst = 0.1 g, m[Bmim]PMoO : m[Bmim]PMoO/10Y-SBA-15 = 25%, and O/S = 4 (molar ratio). In addition, the concentration of aromatics exerted little effect on the DBT ODS. Sulfur compounds in real diesel might be reduced to 8 μg g-1. The hydroxyl radical ˙OH and superoxide radical ˙O2- play crucial roles in the ODS reaction, and the ODS reaction mechanism was also proposed.