Vanadium Containing Metal‐organic Frameworks as Highly Efficient Catalysts for the Oxidation of Refractory Aromatic Sulfur Compounds

Abstract

AbstractThe wet impregnation method was applied to prepare vanadium species on the chromium(III) terephthalate metal‐organic framework (MIL‐101) and on the aluminum fumarate metal‐organic framework (A520), two highly efficient catalysts, as well as vanadium species on the zinc terephthalate metal‐organic framework (MOF‐5), using vanadium(V) oxytributoxide as a precursor. The prepared catalysts were characterized by powder X‐ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT‐IR), scanning electron microscopy (SEM), energy‐dispersive spectroscopy (EDX), N2 sorption measurement (BET), thermal analysis (TGA‐DTA), and X‐ray photoelectron spectroscopy (XPS). The prepared materials were utilized as catalysts for the oxidation of the refractory aromatic sulfur compound, dibenzothiophene (DBT), in a model diesel fuel. The catalytic oxidation of DBT to DBT‐sulfone was performed in the presence of tert‐butyl hydroperoxide (TBHP) under mild operating conditions. The heterogeneous catalysts, OV(OtBu)3−x(OH)x@MIL‐101(Cr), OV(OtBu)3−x(OH)x@A520, and OV(OtBu)3−x(OH)x@MOF‐5 demonstrated activities of 98, 98, and 10 %, respectively, in the oxidative desulfurization (ODS) process at 60 °C. The catalysts were recycled easily and reused without a significant decrease in their activity. The oxidation of DBT to DBT‐sulfone was investigated using gas chromatography, and the formation of DBT‐sulfone was confirmed by FT‐IR and 1H NMR spectroscopies.