Evaluation of Nanoporous Aluminum Silicate Including Active Oxygen Species

抄録

The catalytic activities of propylene oxidation on different aluminum silicates with the mayenite structure [Ca₁₂Al_14−xSi_xO_33+0.5x (x=0,4)] formed at 500, 800 and 1000°C were investigated. The aluminum silicates were prepared by the hydrothermal and solid-state reactions of a stoichiometric mixture of calcium oxide, alumina sol and silica. The XRD results of the aluminum silicates obtained by the solid-state reaction showed that the peak intensities of the mayenite phases became larger as the calcination temperature increased. The aluminum silicates included two kinds of active oxygen species (O₂²⁻, O₂⁻) related to Raman shifts around 887 and 1092 cm⁻¹, respectively. As a result, the aluminum silicates exhibited oxidation activities based on the easily reducible active oxygen species. Notably, the Ca₁₂Al₁₀Si₄O₃₅ calcined at 1000°C without the hydrothermal treatment showed the highest activity of all catalysts, indicating that the crystal structures play an important role in determining the catalytic activity.