Ordered mesoporous γ-alumina (OMA), Ce-doped, Zr-doped and Ce-Zr-codoped OMA samples were synthesized in a sol-gel system with P123 as the soft template, both salicylic acid and citric acid as the assistant templates. The results show that the incorporations of either cerium or zirconium or both are able to improve the thermal stability of OMA. The capability to preserve the structural ordering and suppress the phase transition from γ-Al2O3 to α-Al2O3 at high temperature observed on the doped OMA is due to the formation of CeO2, ZrO2 or Ce(x)Zr(1-x)O2 phase, which is capable of protecting OMA from the structural collapse by sintering and phase transition.
Ordered mesoporous alumina (OMA) samples were prepared via the sol-gel method. The triblock copolymer P123 and aluminum isopropoxide were chose as the template and aluminum source, respectively. The p-aminobenzoic acid (PABA) worked as both the interfacial protector and the assisted template. Different techniques, including X-ray diffractions, N 2 physisorption measurement and transmission electron microscope, were employed to study the structural properties of the prepared samples. The results showed that the mesostructure ordering and specific surface area of the samples highly depend on the quantity of the added PABA. The samples after calcinated at 800°C with the n(PABA)/n(Al 3? ) molar ratio lying in 0.30 exhibited high specific surface areas (301 m 2 g -1 ) and retained an ordered mesostructures. It was indicated that the carboxyl groups of PABA have multiple functions in the formation of OMA with a longrange ordering and high specific surface area. The carboxyl groups of PABA can slow down the hydrolysis-condensation reaction of aluminum isopropoxide, reduce the influence of chloride ions on self-assembly process. The amino groups of PABA can also react with the hydrogen ions to form quaternary ammonium salt, which can neutralize the charges of the chloride ions, protect the balance of inorganic-organic interface, further to improve the mesostructure ordering and specific surface area of the prepared OMA.
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