Ultrasound-assisted oxidative desulfurization of model fuel oil using HPW/Al₂O₃/PANI composite: experimental and...

In the present study, a novel composite catalyst HPW/Al₂O₃/PANI (γ-Al₂O₃, phosphotungstic acid (HPW), polyaniline (PANI)) was synthesized via the ultrasonic-assisted method. It was thoroughly characterized using XRD, FTIR, BET-BJH, FE-SEM, EDS, and TGA techniques. The as-synthesized catalyst was applied for ultrasound-assisted oxidative desulfurization to remove benzothiophene and dibenzothiophene from model hydrocarbon fuel. Response surface methodology (RSM), employing the Box-Behnken design (BBD), was utilized to systematically evaluate and optimize the influence of key process variables, including temperature, oxidant/sulfur (mol/mol), and catalyst loading (g/L). It was found the maximum removal of sulfur containing compounds was achieved through oxidant/sulfur (mol/mol.): 4.15, reaction temperature: 52.85 °C and catalyst/fuel (g/L): 3.26. Kinetic analysis demonstrated that the UAOD process followed the pseudo-first-order reaction kinetic model. Furthermore, the catalyst exhibited excellent reusability over five successive cycles, demonstrating high structural stability and potential for practical applications.