Integrated desulfurization of diesel by combination of metal-free oxidation and product removal by molecularly imprinted polymers

Abstract

The production of ultra-low-sulfur diesel is an important worldwide demand. In this work a novel integrated method for desulfurization of diesel is proposed based on the combination of Brønsted acid catalyzed oxidation and the selective removal of the oxidized products using a molecularly imprinted polymer (MIP) produced in supercritical carbon dioxide (scCO₂). The biphasic oxidation reaction of dibenzothiophene sulfone (DBT), as model substrate, and H₂O₂ as oxidant, was optimized by testing different acid catalysts, and also different phase transfer catalysts (PTC), including two different ionic liquids (ILs) trihexyl(tetradecyl)phosphoniumchloride [P_6,6,6,14]Cl and Aliquat®. The products of the efficient oxidation of DBT, dibenzothiophene sulfoxide (DBTSO) and dibenzothiophene sulfone (DBTSO₂), were then selectively removed from real diesel using the MIP.