Investigation of HPW/SBA-15/PAni nanocomposite as a new heterogeneous catalyst in the ultrasound-assisted oxidative desulfurization process: Experimental, Statistical analysis and optimization

A novel nanocomposite, HPW/SBA-15/PAni, was successfully synthesized based on SBA-15, phosphotungstic acid, and polyaniline (PANI) for ultrasound-assisted oxidative desulfurization (UAOD) applications. The samples were characterized by XRD, UV-DRS, FE-SEM, EDX-elemental mapping, TEM, FT-IR, TGA, and BET-BJH techniques. A system of model fuel including benzothiophene and dibenzothiophene in n-octane was studied. To extract the sulfones produced at the end of the oxidation reaction, acetonitrile was used. The effect of the three important operating factors, including reaction temperature ( °C), oxidant to sulfur molar ratio (mol./mol.), and catalyst/fuel (g/L), were examined using the design of the experiment carried out by the Box-Behnken method. Additionally, the response surface methodology (RSM) was used to optimize the operating conditions. Results showed that BT and DBT removal efficiency from model fuel in optimum conditions were 83 % and 92 %. The results showed that the sulfur oxidation kinetics followed the pseudo-first-order kinetic model. The HPW/SBA-15/PAni catalyst could be reused 5 times successfully without any significant decrease in its catalytic activity. Using these new nanocatalysts, a valuable insight to the design of other catalysts in water oxidation reactions was developed.