Catalytic oxidative desulfurization (ODS) of fuel oil has received much attention. For this, the synthesis of a highly efficient ODS catalyst has been strongly pursued. Polyoxometalates (POMs) as active centers have been studied for ODS reactions. However, generally the obtained POM catalysts exhibited ordinary catalytic ODS performance mainly due to the role of single active sites. Moreover, the synthesis needs to be completed with the addition of solvent. In this work, we report a new approach to prepare highly efficient ODS catalysts with POM sites. This process can be simply realized by the combination of a common POM (H₃PW₁₂O₄₀) and a stable metal–organic framework (MOF) material UiO-66(Zr) without the addition of solvent. More importantly, it is found that polyoxometalate encapsulated in UiO-66(Zr) possesses hierarchical porosity and double active sites. As a result, the catalyst exhibited extraordinary catalytic activity by using H₂O₂ as an oxidant in the ODS reactions of benzothiophene, dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene. The turnover frequency (TOF) for the removal of DBT reached 293 h⁻¹ at room temperature, which is much higher than that of the reported catalysts. Such outstanding catalytic performance could be mainly attributed to easy accessibility of active sites and the existence of two types of active centers in polyoxometalate species and defective UiO-66(Zr).

The demand for xylenes is projected to increase over the coming decades. The separation of xylene isomers, particularly p- and m-xylenes, is vital for the production of numerous polymers and materials. However, current state-of-the-art separation is based upon fractional crystallisation at 220 K which is highly energy intensive. Here, we report the discrimination of xylene isomers via refinement of the pore size in a series of porous metal–organic frameworks, MFM-300, at sub-angstrom precision leading to the optimal kinetic separation of all three xylene isomers at room temperature. The exceptional performance of MFM-300 for xylene separation is confirmed by dynamic ternary breakthrough experiments. In-depth structural and vibrational investigations using synchrotron X-ray diffraction and terahertz spectroscopy define the underlying host–guest interactions that give rise to the observed selectivity (p-xylene < o-xylene < m-xylene) and separation factors of 4.6–18 for p- and m-xylenes.