Abstract
An alumina multilayer grafted on the surface of MCM-41 produced a mesoporous material with the surface chemical functionality of alumina. The starting MCM-41 material (WPMCM) with a wide pore size distribution, a surface area of 858 m2/g, an average pore diameter of 8.2 nm and a pore volume of 1.75 cm3/g was synthesized by expanding the cetyltrimethylammonium chloride (CTAC) surfactant micelles with mesitylene at a high solubilizant/CTAC ratio of 10. Successive grafting consisting of aluminum butoxide anchoring followed by hydrolysis and calcination steps yielded a gradual increase of the aluminum content in WPMCM. Tetrahedral Al in the silica pore walls and clusters of a separate octahedral Al alumina phase were identified. Four grafting cycles produced a material with a surface area of 542 m2/g and a mean pore diameter of 4nm containing 38 wt.% Al2O3 that displayed chemical surface functionality of pure alumina. The activity of this material in the alkylation of phenol with methanol was 2.3 times higher than the activity of a reference alumina (460 m2/g). The highest activity of grafted alumina in cumene cracking and isopropanol dehydration was achieved at 21 wt.% Al2O3. Independent measurements of surface charging in aqueous solution, of [Mo7O24]6- anions adsorption and of surface acidity indicated that the material grafted with alumina and the reference alumina display similar chemical functionality.
Original language | English |
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Pages (from-to) | 65-81 |
Number of pages | 17 |
Journal | Microporous Materials |
Volume | 49 |
Issue number | 1-3 |
DOIs | |
State | Published - 1 Nov 2001 |
Keywords
- Alumina-coated materials
- MCM-41
- Multi-step grafting
ASJC Scopus subject areas
- General Chemistry
- General Materials Science
- Condensed Matter Physics
- Mechanics of Materials