High dimensionally structured W-V oxides as highly effective catalysts for selective oxidation of toluene

Abstract High dimensionally structured W-V-O catalysts (HDS-WVO) were synthesized by hydrothermal method and catalyst structures were investigated by HAADF-STEM analysis. HDS-WVO were rod-shaped crystals and the cross-sections were constituted by W6O21 pentagonal units and MO6 octahedra (M = V, W), forming heptagonal and hexagonal channels. HDS-WVO catalysts showed excellent catalytic performance for selective oxidation of toluene to benzoic acid, and the activity and the selectivity to benzoic acid were superior to those of state-of-the-art catalysts. After the ion exchange using Cs+, the catalytic activity over HDS-WVO was significantly decreased. Since HAADF-STEM analysis and N2 adsorption revealed that Cs+ was located mainly at the heptagonal channel of HDS-WVO, it can be concluded that toluene oxidation takes place at the heptagonal channel site of HDS-WVO.