Boosting the carbo-catalytic of graphene nanoplatelets by ultrasonication for the oxidative desulfurization of dibenzothiophene

Various types of carbon catalysts are investigated for the oxidative desulfurization (ODS) of dibenzothiophene in the presence of hydrogen peroxides as oxidants. The catalytic performance of graphene nanoplatelets (GNPs) outperform other carbon catalysts, and it can be further boosted by ultrasonication to achieve up to 96% sulfur removal. Through parametric studies of the graphene nanoplatelet catalysts, the removal of sulfur occurs via both strong physical adsorption (-50%) and chemical oxidative desulfurization routes (-32-43%). Modifications of graphene nanoplatelets by ball milling, chemical activation, CO2 gasification and H2SO4-acid treatment have significant effects on the catalytic performance. The H2SO4-acid treatment improves 10% of the sulfur removal and enriches the carbonyl (C = O) functional groups on the GNP catalysts. Only a minor loss of 7% in the ODS performance when the GNP catalysts were reused 3 times. Strong adsorption (-1.49 eV to -2.96 eV) of thiophene model occurs at the planar and armchair edges, while chemisorption (-6.59 eV) at the zigzag edges of GNP catalysts as supported by density functional theory simulations.