Keggin-Type Heteropolyanions Immobilized on Phosphorus Slag Derived SiO2: Synthesis, Characterization, and Their Catalytic Oxidative Desulfurization Activity

Phosphorus slag (P-slag) as a cost-effective source is used for the extraction of mesoporous silica SiO2. The composite materials of the Keggin-type heteropolyanions (HPAs) were anchored on SiO2 and successfully prepared via an impregnation approach. Various approaches including X-ray diffraction, Brunauer-Emmett-Teller, inductively coupled plasma, field emission scanning electron microscopy-energy dispersive spectrum, ultraviolet-visible, temperature-programmed desorption, Fourier transform infrared, and transmission electron microscopy were employed to characterize the samples. HPAs supported on SiO2 were employed for the oxidation of organic sulfur compounds [e.g., benzothiophene (BT), dibenzothiophene (DBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT)] from the model fuel. HPA-loaded SiO2 catalysts illustrated outstanding catalytic activity in the oxidative desulfurization procedure. The removal performance of the DBT using Cs2W9V3/SiO2 was greater than that using other materials under the optimum condition. The maximum level of DBT removal by Cs2W9V3/SiO2 reached 100%. The removal performance of various substrates followed the order DBT > 4,6-DMDBT > BT. The Cs2W9V3-incorporated SiO2 catalyst illustrated brilliant reusability five times with negligible reduction in performance. Besides, the kinetic studies exhibited that the desulfurization procedure on DBT-containing sulfur compound verified a pseudo-first-order kinetic model. The Arrhenius activation energy for the Cs2W9V3/SiO2 catalyst obtained 47.2 kJ/mol.

Automated summary

In this study, mesoporous silica materials with excellent catalytic activity were extracted using phosphorus slag and characterized using various techniques. The HPAs-supported SiO2 catalyst showed outstanding performance in the oxidation desulfurization of organic sulfur compounds in model fuel, with the best removal efficiency observed for DBT. The catalyst exhibited brilliant reusability and followed a pseudo-first-order kinetic model for the desulfurization process.