Flexible encapsulation polyoxometalate with electrostatically interaction into metal−organic framework for ultra-deep aerobic oxidation desulfurization of diesel via a biomimetic approach in deep eutectic solvents

Abstract

Flexible encapsulation of polyoxometalates (POMs) into metal–organic frameworks (MOFs) is a promising and emerging research area. Herein, a novel non-homogeneous IL(CoMo6)-MIL-101-NH2 catalyst was prepared by a stepwise modification method, in which the unprecedentedly flexible encapsulation of POM-MOF catalyst was achieved through ion exchange of introducing (NH4)3H6CoMo6O24 into IL(Br)-MIL-101-NH2. This approach firmly encases the POM within the pores of MIL-101 through electrostatic interactions. It not only preserved the catalytic activity of POM, but also provided sufficient space for the reaction to occur. The IL(CoMo6)-MIL-101-NH2 catalyst retained a high similar activity to homogeneous catalyst, while possessing characteristics of a multiphase catalyst for easy separation and recovery. It tackles POM's solubility issue and enables its encapsulation in MOFs for heterogeneous catalysis. Furthermore, the unparalleled catalyst was utilized in a biomimetic approach for coupling with deep eutectic solvents to achieve ultra-deep aerobic oxidative desulfurization of diesel.