Assembly of Mesoporous Lamellar Silicas with Hierarchical Particle Architectures

作者：Peter T. Tanev, Ying Q. Liang, Thomas J. Pinnavaia · 发表于：Journal of the American Chemical Society · 年份：1997 · DOI：10.1021/ja970228v · 被引用次数：180 · 研究领域：Mesoporous Materials and Catalysis、Polyoxometalates: Synthesis and Applications、Zeolite Catalysis and Synthesis

A family of silica molecular sieves with lamellar frameworks and hierarchical structure (denoted MSU-V) was assembled from homogeneous solutions of neutral H 2 N(CH 2 ) n NH 2 bolaamphiphiles ( n = 12−22) as the structure directors and tetraethylorthosilicate as the inorganic precursor. Optimal lamellar order was observed for four as-synthesized and calcined (550 °C) mesostructures when they were assembled at the following reaction temperatures ( T, °C) and surfactant/silica ratios ( R ) of T = 25 °C, R = 0.26 (C 12 ); T = 45 °C, R = 0.20 (C 16 ); T = 55 °C, R = 0.15 (C 18 ); T = 55 °C, R = 0.11 (C 22 ). MSU-V silica assembled from the short C 12 alkyl chain bolaamphiphile exhibited gallery-confined micropores (1.3 nm), but the derivatives prepared from the longer C 16 −C 22 diamines showed gallery-confined mesopores . As the alkyl chain length of the bolaamphiphile surfactant increased from C 16 to C 22, the size of the gallery-confined mesopores increased from 2.0 to 2.7 nm. The described synthetic strategy afforded hierarchical MSU-V structures with biomimetic multilamellar vesicular particle architectures. Distorted vesicular, plate, and spiral-ribbon shaped particles also were observed, particularly for the lamellar silica assembled from the C 16 bolaamphiphile. The variation in morphologies was attributed to agitation effects during synthesis. MSU-V silica assembled from the C 22 diamine was the least stable member of the series and partially decomposed upon calcination...