Construction of Mo-MOF-derived molybdenum dioxide on carbon nanotubes with tunable nitrogen content and particle size for oxidative desulfurization

The combination of distinctive properties of carbon nanotubes and metal oxides is expected to exploit novel catalysts offering high catalytic ability. Herein, a nano-sized MoO2 derived from molybdenum-based metal-organic framework was anchored on the surface of carbon nanotubes (CNT) with urea as a regulator. Powder X-ray diffraction analysis suggested that the nitrogen content and the MoO2 particle size of the as-prepared catalyst could be tuned by changing the urea dosage and the calcination temperature. Elemental mapping indicated the homogeneous dispersion of the nano-sized MoO2 on the surface of CNT for MoO2@CNT-U7.5 (U7.5 represents mass ratio of urea to CNT). Compared with MoO2@CNT treated in absence of urea, MoO2@CNT-U7.5 showed extremely higher catalytic performance in oxidative desulfurization of fuel. With H2O2 as an oxidant, the removal of refractory sulfur compounds including dibenzothiophene, 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene can reach >99% within 40 min at the reaction temperature of 50 °C. In addition, the catalyst exhibited superior cycling stability and could be recycled for eight times with little loss of sulfur removal. The reaction mechanism was eventually proposed with the assistance of GC–MS and ESR analysis.