Cyclohexane photocatalytic oxidative dehydrogenation to benzene on sulphated titania supported MoO_x

摘要

The effect of sulphate on the photocatalytic properties of MoO_x/TiO_2 catalysts for cyclohexane photocatalytic oxydehydrogenation has been investigated with a gas-solid continuous flow reactor. Photocatalytic tests performed on anatase titania at different sulphate content, ranging from 0 to 2 wt%, have shown that only the total oxidation of cyclohexane occurs. Cyclohexane conversion to carbon dioxide at steady state conditions decreases as the sulphate load increases. Photocatalytic oxidative dehydrogenation of cyclohexane to benzene has been studied on MoO_3 4.7 wt % supported on sulphated titania. The presence of sulphate species on the surface of titania enhances selectivity and yield to benzene as more as higher is the sulphate content. On the catalyst with the highest sulphate content very high selectivity to benzene was obtained, very weakly dependent of cyclohexane conversion. The selectivity properties of MoO_x/TiO_2 catalysts are associated to the presence of both sulphate and polymolybdate species on the titania surface.