Efficient oxidative desulfurization of dibenzothiophene using molybdenum-based catalysts loaded the functionalized UiO-66

A series of ligand-modified loaded molybdenum-based catalysts were prepared using UiO-66 functionalized with organic ligands. The catalyst structures were characterized by XRD, FT-IR, BET, TEM and XPS. The characterizations revealed that the –NO2 and –NH2 groups were successfully grafted onto the carrier UiO-66. The overall structure of the catalysts did not undergo any significant changes, and the active components of the catalysts were uniformly dispersed on the UiO-66. The effect of the catalyst structure on the catalytic activity was investigated by using the removal of dibenzothiophene (DBT) from simulated oil, it was found that the catalyst functionalized with the –NO2 group (UiO-66-NO2-MoO(O2)2) was the most effective for the desulfurization, and the DBT conversion of the catalyst reached 98.79 % under the optimal reaction conditions. The catalyst functionalized with –NH2 group (UiO-66-NH2-MoO(O2)2) was found to have better recyclability in the cycling experiments. Combining the results of various characterizations and free radical trapping experiments, it was observed that the introduction of the –NO2 group improved the microenvironment on the carrier surface and around the active center of the catalyst, resulting in the production of more (•OH) around the molybdenum species, which contributed to the catalytic performance of the catalyst.