Exceptional structure flexibility and adaptive catalytic desulfurization of a cyclic decanuclear polyoxoalkoxyvanadate (Ⅲ)

Removal of notorious organic sulfur-containing compounds to produce low-sulfur-content diesel is of great significance in developing modern industry and addressing environmental protection, but the key challenge is to seek recyclable heterogeneous catalysts with high efficiency. Herein, an intelligent regulation structural polyoxometalate-based hybrid compound with a ten-membered ring cluster has been synthesized via facile solvothermal method, formulated as [VIII10(μ2-OCH3)20(CH3CO2)10] (V10). Single crystal diffraction shows that every two adjacent vanadium ions in V10 are connected by methoxides and acetate group to construct a ten-membered wheel ring. It is noteworthy that the center of the ring can exhibit different opening and closing states through the disordered methoxy groups with rotational/oscillatory flexibility without disrupting the main structure of the ring, being analogous to IRIS stop of an optical camera. Notably, sulfur oxidation experiments indicated that V10 as heterogeneous catalyst displayed excellent catalytic activity, selectivity and stability for the catalytic oxidation of dibenzothiophene (DBT) at mild condition, which outperforms most of reported vanadium oxygen clusters. Benefiting from the multi-modal transformation of the inner ring structure, the catalyst can adaptively adjust the position of methoxy groups to make the sulfides more accessible to the active site, thus facilitating the conversion of DBT up to >99% in 40 ​°C. This study affords a novel perspective for the development of polyoxovanadates with better performance.