Mesoporous SnO-MoO catalyst for diesel oxidative desulfurization: Impact of the SnO/MoO ratio on catalytic efficiency.

Vehicular SO emissions have a huge detrimental impact on public health, catalytic converters, and the environment. Developing strategies to remove sulfur from diesel and thus safeguard the above is imperative. A series of SnO-MoO mixed oxides and mono oxides MoO and SnO were prepared by soft template method, calcined at 450 °C and successfully tested in model diesel oxidative desulfurisation (ODS). The impact of the SnO/MoO mole ratio (hereinafter denoted as Sn/Mo) on catalytic efficiency was investigated, among other catalytic parameters. The obtained samples were analyzed using X-ray diffraction (XRD), Raman spectrocscopy, scanning electron microscopy (SEM), N-physisorption and titration method for acidic properties. The study demonstrates that mixing SnO and MoO improves acidic sites, crystallinity, and morphological properties of pure SnO. The addition of MoO increased oxygen vacancies and the surface area of SnO. High acidic site densities of 49.3, 47.4, and 46.7 mEqg were observed for the catalysts with 2:1, 1:1, and 1:2 Sn/Mo mole ratio, respectively. The catalytic efficiency increased with an increase in Sn content with the highest catalytic efficiency of 99.8% for the dibenzothiophene (DBT) oxidation achieved in 30 min for Sn/Mo (2:1) catalyst compared to 92 and 70% for Sn/Mo 1:1 and 1:2 catalysts, respectively. The rate constant for the reaction was 0.057 min, which is eight times that of MoO; 0.007 min and three times that of SnO; 0.017 min. The ODS mechanism utilizing the SnO-MoO catalyst was proposed. The prepared SnO-MoO catalyst demonstrated a high potential for industrial desulfurisation applications.