Incorporating carbon quantum dots into phosphotungstic acid ionic liquid materials for enhanced catalytic oxidative desulfurization

SOx emission from fossil fuel combustion is an important reason for environmental pollution. Achieving deep removal of sulfur-containing compounds from the fuel is essential. Herein, by combining phosphotungstic acid (HPW) with ionic liquids (ILs) and incorporating carbon quantum dots (CQDs), a series of catalysts (CQD/C18PWIL-x) for oxidative desulfurization (ODS) are prepared. Experimental results reveal that the modification of ILs could facilitate full contact between the active site and the organic phase, and improve mass transfer in the oxidative desulfurization process. Moreover, the incorporation of CQDs can promote the utilization of hydrogen peroxide. The synergistic action of multiple components leads to better activation of hydrogen peroxide. Therefore, the CQDs/C18PWIL-1 exhibits excellent desulfurization efficiency under ambient conditions, in which dibenzothiophene was completely removed within 30 min. Meanwhile, as heterogeneous catalyst, CQDs/C18PWIL-1 shows excellent cycling stability. The direct incorporation of CQDs significantly improves the catalytic activity and provides a new inspiration for the application of CQDs to ODS processes.