Facile synthesis for ordered mesoporous gamma-aluminas with high thermal stability.
The facile synthesis of highly ordered mesoporous aluminas with high thermal stability and tunable pore sizes is systematically investigated. The general synthesis strategy is based on a sol-gel process associated with nonionic block copolymer as templates in ethanol solvent. Small-angle XRD, TEM, and nitrogen adsorption and desorption results show that these mesoporous aluminas possess a highly ordered 2D hexagonal mesostructure, which is resistant to high temperature up to 1000 degrees C. Ordered mesoporous structures with tunable pore sizes are obtained with various precursors, different acids as pH adjustors, and different block copolymers as templates. These mesoporous aluminas have large surface areas (ca. 400 m2/g), pore volumes (ca. 0.70 cm3/g), and narrow pore-size distributions. The influence of the complexation ability of anions and hydro-carboxylic acid, acid volatility, and other important synthesis conditions are discussed in detail. Utilizing this simple strategy, we also obtained partly ordered mesoporous alumina with hydrous aluminum nitrate as the precursor. FTIR pyridine adsorption measurements indicate that a large amount of Lewis acid sites exist in these mesoporous aluminas. These materials are expected to be good candidates in catalysis due to the uniform pore structures, large surface areas, tunable pore sizes, and large amounts of surface Lewis acid sites. Loaded with ruthenium, the representative mesoporous alumina exhibits reactant size selectivity in hydrogenation of acetone, D-glucose, and D-(+)-cellobiose as a test reaction, indicating the potential applications in shape-selective catalysis.
Yuan
Quan
Q
Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China.
Yin
An-Xiang
AX
Luo
Chen
C
Sun
Ling-Dong
LD
Zhang
Ya-Wen
YW
Duan
Wen-Tao
WT
Liu
Hai-Chao
HC
Yan
Chun-Hua
CH
D000537:Aluminum Oxide / Q000138:chemical synthesis* / Q000737:chemistry; D003460:Crystallization; D000431:Ethanol / Q000737:chemistry; D005782:Gels / Q000737:chemistry; D006358:Hot Temperature; D010316:Particle Size; D016062:Porosity; D015203:Reproducibility of Results; D013499:Surface Properties; D013696:Temperature
D005782:Gels; D000431:Ethanol; D000537:Aluminum Oxide