Synthesis and Characterization of a New Nanocatalyst Based on Keggin-Type Polyoxovanadate/Nickel-Zinc Oxide, PV14/NiZn2O4, as a Potential Material for Deep Oxidative Desulfurization of Fuels

Abstract

On account of the undesirable sulfur compounds in gasoline, a new heterogeneous catalyst (PV14/NiZn2O4) was synthesized successfully by immobilizing Keggin-type polyoxovanadate (K9[PV14O42]·11H2O) (abbreviated as PV14) on the surface of nickel-zinc oxide (NiZn2O4). The physicochemical characteristics of the nanocomposite as well as its individual constituents were identified by Fourier transform infrared (FTIR), ultraviolet–visible (UV–vis), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and thermogravimetric analysis-differential thermogravimetry (TGA-DTG) techniques. The characterization outcomes indicated that PV14 was uniformly dispersed over the surface of NiZn2O4. The PV14/NiZn2O4 nanocatalyst was served for catalytic oxidative desulfurization (Cat-ODS) of sulfur compounds in real gasoline and model fuel oils (MFOs) with 3 mL of H2O2/AcOH oxidizing agent (volume ratio of 2:1). The optimum conditions for the Cat-ODS process were obtained using 0.1 g of the PV14/NiZn2O4 nanocatalyst at 35 °C after 60 min under atmospheric pressure. Based on the experimental results described above, it was observed that the total concentration of sulfur present in authentic gasoline underwent a substantial reduction from 0.4987 to 0.0143 wt %, denoting an efficiency of 96%. Moreover, the elimination of sulfur from MFOs, which are difficult to remove, could reach up to 95% at the same reaction conditions. Furthermore, the catalytic efficacy of PV14/NiZn2O4 was sustained for five cycles, without any notable reduction in its performance. Finally, the mechanism of Cat-ODS was proposed through the generation of oxo–peroxo intermediate species.