Direct Synthesis of H2O2over Ti-Containing Molecular Sieves Supported Gold Catalysts: A Comparative Study for In-situ-H2O2-ODS of Fuel

Abstract

Direct synthesis of <TEX>$H_2O_2$</TEX> and in situ oxidative desulfurization of model fuel over Au/Ti-HMS and Au/TS-1 catalysts has been comparatively investigated in water or methanol. Maximum amount (82%) of active <TEX>$Au^0$</TEX> species for <TEX>$H_2O_2$</TEX> synthesis was obtained. Au/Ti-HMS and Au/TS-1 exhibited the contrary performances in <TEX>$H_2O_2$</TEX> synthesis as <TEX>$CH_3OH/H_2O$</TEX> ratio of solvent changed. <TEX>$H_2O_2$</TEX> decomposition and hydrogenation in water was inhibited by the introduction of methanol. Effect of <TEX>$O_2/H_2$</TEX> ratio on <TEX>$H_2O_2$</TEX> concentration, <TEX>$H_2$</TEX> conversion and <TEX>$H_2O_2$</TEX> selectivity revealed a relationship between <TEX>$H_2O_2$</TEX> generation and <TEX>$H_2$</TEX> consumption. The highest dibenzothiophene removal rate (83.2%) was obtained over Au/Ti-HMS in methanol at 1.5 of <TEX>$O_2/H_2$</TEX> ratio and <TEX>$60^{\circ}C$</TEX>. But removal of thiophene over Au/TS-1 should be performed in water without heating to obtain a high removal rate (61.3%). Meanwhile, <TEX>$H_2$</TEX> conversion and oxidative desulfurization selectivity of <TEX>$H_2$</TEX> were presented.