Preparation of MoO2/g-C3N4 composites with a high surface area and its application in deep desulfurization from model oil

A series of catalysts of composition X -MoO 2 /g-C 3 N 4 ( X   =   0, 0.5, 1, 3, 5   wt.%) were successfully synthesized by calcination of a mixture of (NH 4 ) 6 Mo 7 O 24 ·4H 2 O and g-C 3 N 4 . Oxidative desulfurization experiments were conducted using X -MoO 2 /g-C 3 N 4 as a catalyst, H 2 O 2 as an oxidant, and ionic liquids (ILs) as extraction agents. Catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FT-IR), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), and Brunauer-Emmett-Teller analysis (BET). Characterization results suggested that MoO 2 was present in the catalyst and its crystallinity improved with increased Mo-loading. The catalysts had a larger specific surface area due to the presence of MoO 2 dispersed on g-C 3 N 4 . Experimental results showed that 3%-MoO 2 /g-C 3 N 4 had the highest catalytic activity among all the catalysts tested. A desulfurization rate of 96.0% was achieved under optimal conditions. Through gas chromatography-mass spectrometry (GC–MS) analysis, it was shown that dibenzothoiphene sulfone was the sole product of the oxidation desulfurization reaction. An apparent activation energy of 61.1   kJ/mol was estimated based on Arrhenius equation. The activity of 3%-MoO 2 /g-C 3 N 4 slightly decreased after six runs. A possible mechanism for the reaction has been proposed.