Design and synthesis of defect-engineered POM@MOF catalysts for aerobic oxidative desulfurization

Abstract

In this study, PW₅V₇@rht-MOF-1 (1) was prepared via one-pot hydrothermal synthesis and its crystal structure was confirmed by X-ray diffraction analysis. To enhance catalytic performance, a series of defect-engineered PW₅V₇@rht-MOF-1 (1-D_x) catalysts were further developed by using formic acid (FA) as a modulator. TG, PXRD, and BET analyses demonstrated that defects resulting from ligand deficiency in 1-D_x enhanced their specific surface area and porosity, while maintaining the overall structural integrity. XPS, EPR and Py-IR analyses revealed the presence of additional oxygen vacancies and Lewis acid sites in 1-D_0.2. Experimental results show that, with the assistance of the surfactant, the optimized catalyst (1-D_0.2) achieves 99.8% sulfur removal within 3 h at 100 °C, significantly improving upon the defect-free catalyst (71.1%). Cycle tests indicate that 1-D_0.2 maintains 93.4% desulfurization efficiency after seven consecutive uses, demonstrating its structural stability. In addition, the radical oxidation mechanism of the AODS reaction was further validated by radical scavenging experiments and EPR. This study presents a novel strategy for designing defect-engineered POM@MOF catalysts and demonstrates their application in deep fuel desulfurization, highlighting the crucial role of defect engineering in heterogeneous catalysis.