The Green Preparation of ZrO2-Modified WO3-SiO2 Composite from Rice Husk and Its Excellent Oxidative Desulfurization Performance

Recently, the resource utilization of agricultural biomass wastes for the preparation of a wide range of high-value-added chemicals and functional materials, especially heterogeneous catalysts, has received extensive attention from researchers. In this work, mesoporous WO3/ZrO2-SiO2 catalysts are prepared by a two-step incipient-wetness impregnation method using agricultural biomass waste rice husk (RH) as both the silicon source and mesoporous template. The effects of different WO3 and ZrO2 loadings on the oxidative desulfurization (ODS) performance of samples are investigated, and the suitable WO3 and ZrO2 loadings are 11 and 30%, respectively. The relevant characterization results indicate that, compared to 11%WO3/SiO2, the introduction of ZrO2 leads to the formation of stronger W-O-Zr bonds, which makes the tungsten species stabilized in the state of W6+. The strong preferential interaction between Zr and W facilitates the formation of stable and highly dispersed WOx clusters on the mesoporous ZrO2-SiO2 carrier. Furthermore, it also prevents the formation of WO3 crystallites, significantly reducing their content and thus inhibiting the loss of the WO3 component during cycling experiments. Therefore, the 11%WO3/30%ZrO2-SiO2 sample shows excellent catalytic activity and recycling performance (DBT conversion reaches 99.2% after 8 cycles, with a turnover frequency of 12.7 h–1; 4,6-DMDBT conversion reaches 99.0% after 7 cycles, with a turnover frequency of 6.3 h–1). The kinetics of the ODS reactions are further investigated. The mechanism of the ODS reaction is explored through experiments involving leaching, quenching, and the capture of the active intermediate. Finally, a possible reaction mechanism for the ODS process for the 11%WO3/30%ZrO2-SiO2 sample is proposed.