Photo-oxidation over mesoporous V-TiO_2 catalyst under visible light monitored by vanadium Kβ_(5,2)-selecting XANES spectroscopy

摘要

Visible light-excited ethanol dehydration reaction steps to adsorb ethanol and then to donate an electron to transform V(IV) to V(III) site exposed on mesoporous V(IV)-TiO_2 catalyst were successfully monitored by means of V Kβ_(5,2)-selecting XANES spectroscopy. Spherically-bent Ge(422) crystal was used for the X-ray fluorescence analyses and Xe arc lamp of 500 W was illuminated at 10 mm apart from catalyst samples under on reaction conditions. Specific redox reaction mechanism between V(IV) and V(III) states was proposed for dehydration reaction over the mesoporous V-TiO_2 catalyst based on the V Kβ_(5,2)-seIecting XANES compared to general vanadium catalysts starting from V(V) state for dehydrogenation reaction.