Untitled

Preparation and characterization of monolithic Al₂O₃–SiO₂ aerogel

“…There are two main causes for this phenomenon: stabilization of the crystal structure of alumina by addition of silica, and low density. 19) …”

“…5(b), when the temperature promoted to 1200°C, the strong diffraction peaks of 3Al1Si are observed, which are characteristic of the mullite phase. Horiuchi T et al 19) pointed out that the mullite phase is compounded as the mole ratio of Al 2 O 3 /SiO 2 = 2/13/2. Meanwhile, within 6001000°C, the wide width bread peak is observed at 25°(2ª) that is characteristic of the amorphous SiO 2 .…”

Effect of Si-Doping on Thermal Stability and Diesel Oxidation Activity of Pt Supported Porous γ-Al2O3 Monolithic Catalyst

“…[8,17]. To better understand the principle, we measured the NMR of SA-10.0-1100 sample with the high thermal stability.…”

“…and Al 3? [8], thereby decreasing the total number of vacancies and suppressing the lattice vibration of alumina at high temperature. If Si atoms occupy all of tetrahedral sites and Al atoms occupy all of octahedral positions, the theoretical content of SiO 2 is ca.…”

“…When n = 0, it implies none hydroxyl groups, suggesting that all Al 3? ions are only in octahedral positions and alumina completely transforms to a phase. Horiuchi et al [8] summarized that the suppression mechanism of phase transformation for alumina was the stabilization of the crystal structure and the low bulk density. It was reported that Si was a more excellent promoter than La and Ba, because the incorporation of Si may produce a glassy surface layer on alumina [9], which can theoretically decrease the bulk density and retard the transformation from c-into a-alumina.…”