In situ bridging encapsulation of a carboxyl-functionalized phosphotungstic acid ionic liquid in UiO-66: A remarkable catalyst for oxidative desulfurization

This work describes a novel approach for linking metal-organic frameworks (MOFs) to polyoxometalates (POMs) for use as effective heterogeneous catalysts in the oxidative desulfurization of fuel oil. A POM-based MOF was synthesized in situ with a carboxyl-functionalized ionic liquid as a bridge to combine the POM and MOF. The resulting [mim(CH2)(3)COO](3)PW@UiO-66 was characterized by XRD, N-2 adsorption-desorption, FT-IR, SEM and TGA. The results indicated that the heteropolyanion-based ionic liquid [mim(CH2)(3)COOH](3)PW was successfully dispersed within the cages of UiO-66. The catalyst [mim (CH2)(3)COO](3)PW@UiO-66, which had a high content of the active component and large specific surface area, exhibited remarkable catalytic performance in oxidative desulfurization (100% DBT removal in 60 min). Importantly, a synergistic catalytic mechanism involving W = O and the Lewis acid, in which the Lewis acid promoted the decomposition of H2O2 and the generation of peroxotungstate (W(O-2)(n)), was proposed to explain the high oxidative desulfurization catalytic efficiency of [mim (CH2)(3)COO](3)PW@UiO-66. (c) 2020 Elsevier Ltd. All rights reserved.