Highly efficient deep desulfurization of fuels by chemical oxidation

This paper describes the oxidation of several model S-containing molecules with hydrogen peroxide in L–L phase system using a heterogeneous catalyst under atmospheric pressure in the 333–353 K temperature range. Molybdenum and tungsten compounds are prepared by anion exchange with alkylammonium derivatives covalently anchored to silica gel. These solids are robust heterogeneous catalysts able to activate selectively hydrogen peroxide to remove sulfur compounds via oxidation (ODS). The influence of several reaction variables (the reaction temperature, the nature of the substrate, the solvent, the molar ratio of the oxidant (H2O2), the S-containing molecule, the catalysts nature and the reuse of the catalysts) on the performance was examined. The potential of this methodology is illustrated by the complete S removal from a 0.2 wt% dibenzothiophene mixture at 353 K in less than 1 h of reaction. Molybdenum catalysts exposed to hydrogen peroxide form peroxomolybdates moieties which are more active than acid precursors. The activated Mo catalysts are very active in ODS reaction and can be reused four times without lose of activity.