Nanocrystalline Mesoporous -Alumina Powders "UPMC1 Material" Gathers Thermal and Chemical Stability with High Surface Area
详细信息 查看全文
- 作者：Cé ; dric Boissiè ; re ; Lionel Nicole ; Christelle Gervais ; Florence Babonneau ; Markus Antonietti ; Heinz Amenitsch ; Clé ; ment Sanchez ; David Grosso
- 刊名：Chemistry of Materials
- 出版年：2006
- 出版时间：October 31, 2006
- 年：2006
- 卷：18
- 期：22
- 页码：5238 - 5243
- 全文大小：279K
- 年卷期：v.18,no.22(October 31, 2006)
- ISSN：1520-5002
文摘
The designed elaboration of alumina sub-micrometric spherical powder that combines 3D orderedmesoporosity of high accessibility, nanocrystalline structure, and thermal stability up to 900 
C is reported.The strategy used to elaborate such new materials labeled "UPMC1" involves specific block-copolymertemplating, aluminum sol-gel chemistry, tuned aerosol generation (spray drying), and sequential thermaltreatments that allow designing of a whole set of mesoporous catalytic supports by adjusting ceramizationconditions between 700 and 900 C. When calcination temperature reaches 700 C, the network remainsamorphous and displays structural features of highly porous materials (i.e., porosity, 0.56 cm3·g-1; surfacearea, 403 m2·g-1; well-calibrated pore diameter, 13 nm). After 30 min at 900 C, crystallization into
-Al2O3 particles of around 6 nm has occurred, which has modified the network characteristics (i.e.,porosity, 0.34 cm3·g-1; surface area, 134 m2·g-1; well-calibrated pore diameter, 12.5 nm) without destroyingthe mesostructure. Both amorphous and crystalline final materials present the remarkable properties ofmesoporous materials with the unique amphoteric properties of the -alumina surface (40% of tetragonalacid sites) that have great potential application in catalysis, in environment, and as an adsorbent. Thepresent work points out that ordered mesoporosity has the ability to stabilize materials with amorphousor metastable crystalline structure at higher temperatures than what is observed for nonordered mesoporousanalogous systems. Such a phenomenon is discussed on the basis of extensive materials characterizationmainly based on TEM, XRD, and 29Al high-resolution solid-state NMR.
C is reported.The strategy used to elaborate such new materials labeled "UPMC1" involves specific block-copolymertemplating, aluminum sol-gel chemistry, tuned aerosol generation (spray drying), and sequential thermaltreatments that allow designing of a whole set of mesoporous catalytic supports by adjusting ceramizationconditions between 700 and 900 C. When calcination temperature reaches 700 C, the network remainsamorphous and displays structural features of highly porous materials (i.e., porosity, 0.56 cm3·g-1; surfacearea, 403 m2·g-1; well-calibrated pore diameter, 13 nm). After 30 min at 900 C, crystallization into-Al2O3 particles of around 6 nm has occurred, which has modified the network characteristics (i.e.,porosity, 0.34 cm3·g-1; surface area, 134 m2·g-1; well-calibrated pore diameter, 12.5 nm) without destroyingthe mesostructure. Both amorphous and crystalline final materials present the remarkable properties ofmesoporous materials with the unique amphoteric properties of the -alumina surface (40% of tetragonalacid sites) that have great potential application in catalysis, in environment, and as an adsorbent. Thepresent work points out that ordered mesoporosity has the ability to stabilize materials with amorphousor metastable crystalline structure at higher temperatures than what is observed for nonordered mesoporousanalogous systems. Such a phenomenon is discussed on the basis of extensive materials characterizationmainly based on TEM, XRD, and 29Al high-resolution solid-state NMR.