In this study, Keggin- and Dawson-type polyoxometalates (POMs) were immobilized on chitosan (CS)-modified Fe₃O₄@CS by electrostatic interaction for the preparation of heterogeneous catalysts Fe₃O₄@CS@POM (POM=PMo₁₂, PW₁₂, SiW₁₂, P₂W₁₇, or P₂W₁₈). The oxidative desulfurization (ODS) of dibenzothiophene (DBT) by Fe₃O₄@CS@POMs was evaluated. It is found that Fe₃O₄@CS@POM shows the good ODS performance due to the good dispersion of POM on Fe₃O₄ surface and the good accessibility of substrate to it leaded by the full swelling of the cross-linked CS in acetonitrile. The catalytic activity follows the order of Fe₃O₄@CS@PMo₁₂ > Fe₃O₄@CS@PW₁₂ > Fe₃O₄@CS@P₂W₁₇ > Fe₃O₄@CS@P₂W₁₈ > Fe₃O₄@CS@SiW₁₂. At 333 K, the desulfurization rate of DBT (500 ppm) reaches 99.7% at 60 min and 100% at 90 min in the presence of 0.1 g of Fe₃O₄@CS@PMo₁₂ and 100 µL of H₂O₂. The ODS process can be well described by the pseudo-first-order kinetic model (R² > 0.99) with a high kinetic constant (0.0761 min⁻¹) and a low apparent activation energy (60.57 kJ / mol). In addition, the as-prepared catalyst can be easily separated and recycled in the external magnetic field, and it still has the good reusability for several times, stemming from the stable encapsulation of POM clusters by cross-linked chitosan on Fe₃O₄ surface.

在这项研究中，通过静电相互作用将Keggin型和Dawson型多金属氧酸盐（POM）固定在壳聚糖（CS）修饰的Fe ₃ O ₄ @CS上，以制备非均相催化剂Fe ₃ O ₄ @ CS @ POM（POM = PMo ₁₂，PW ₁₂，SiW ₁₂，P ₂ W ₁₇或P ₂ W ₁₈）。评估了Fe ₃ O ₄ @ CS @ POMs对二苯并噻吩（DBT）的氧化脱硫（ODS）。发现由于POM在Fe ₃上的良好分散，Fe ₃ O ₄ @ CS @ POM表现出良好的ODS性能。O ₄表面和底物的良好可及性是由于交联的CS在乙腈中完全溶胀而导致的。催化活性依次为Fe ₃ O ₄ @ CS @ PMo ₁₂ > Fe ₃ O ₄ @ CS @ PW ₁₂ > Fe ₃ O ₄ @ CS @ P ₂ W ₁₇ > Fe ₃ O ₄ @ CS @ P ₂ W ₁₈ > Fe ₃ O ₄ @ CS @ SiW ₁₂。在333 K下，在存在0.1 g Fe的情况下，DBT（500 ppm）的脱硫率在60分钟时达到99.7％，在90分钟时达到100％₃ O ₄ @ CS @ PMo ₁₂和100 µL H ₂ O ₂。通过具有高动力学常数（0.0761min ^-1）和低表观活化能（60.57kJ / mol）的伪一级动力学模型（R ² > 0.99）可以很好地描述ODS过程。此外，制得的催化剂可以很容易地在外部磁场中分离和再循环，并且由于交联壳聚糖在Fe ₃ O ₄表面上对聚甲醛团簇的稳定包封，其仍具有良好的可重复使用性。。