UiO-66(Zr)-based porous ionic liquids for highly efficient extraction coupled catalytic oxidative desulfurization

Abstract

Porous ionic liquids are a novel category media that possesses the catalytic activity of porous solids and the extraction property of ionic liquids. Herein, a new type of porous ionic liquids (denoted as UiO-66-T3PILs) was fabricated by employing UiO-66(Zr) as the pore generator and the ionic liquid ([P6,6,6,14][NTF2]) as the size-excluded solvent for extraction coupled catalytic oxidative desulfurization (ECODS) using hydrogen peroxide (H2O2, 30 wt%) as an oxidant. Furthermore, several significant reaction parameters such as UiO-66 loading in porous ionic liquids, reaction temperatures, molar ratio of H2O2/DBT and sulfide species as well as recyclability were investigated in detail. As UiO-66-T3PILs exhibited higher efficiency (95.3%) than the summarized efficiency of UiO-66 and [P6,6,6,14][NTF2], there did exist a synergistic effect between the UiO-66(Zr) moiety and the ionic liquid moiety in UiO-66-T3PILs. With the assistance of density functional theory calculations, a possible mechanism was proposed that aromatic sulfur compounds in the oil phase were first extracted into ionic liquids moiety phase via C-H···π interactions and then rapidly oxidized by OH radicals in the presence of the UiO-66 moiety. This work will pave the way for the rational design of novel porous ionic liquids towards catalysis.