About the thermal stability and pore elimination in the ordered hexagonal mesoporous silica SBA-15
| Autor: | Dimas R. Vollet, F. S. De Vicente, Dario A. Donatti, T. da Silveira, Carlos M. Awano |
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| Rok vydání: | 2014 |
| Předmět: |
chemistry.chemical_classification
Materials science Small-angle X-ray scattering General Chemistry Activation energy Polymer Mesoporous silica Condensed Matter Physics law.invention Crystallography Lattice constant Chemical engineering chemistry Mechanics of Materials law General Materials Science Calcination Thermal stability Porosity |
| Zdroj: | Microporous and Mesoporous Materials. 190:227-233 |
| ISSN: | 1387-1811 |
| Popis: | Ordered hexagonal mesoporous silica was prepared using Pluronic P123 template and removal of the polymer by washing in ethanol. The thermal stability and the pore elimination was studied under heat treatment by a fixed time at 500, 600, 750, 825, 900, and 1050 °C. The most part of the porosity is built up by cylindrical pores belonging to the ordered hexagonal 2D pore structure. The lattice parameter and the pore volume of the hexagonal 2D structure diminish regularly with the temperature up to 900 °C. All porosity is eliminated at 1050 °C. The porosity elimination occurs in a mechanism described by a geometric model of contracting area, in which the diameter of the cylindrical pore diminishes while its length is kept constant. An activation energy of (92 ± 2) kJ/mol was estimated for the process. The ordered porosity of an ethanol-washed and vacuum dried sample was found to be even larger with a narrower pore size distribution in comparison to a sample directly calcined at 500 °C without previous washing in ethanol. |
| Databáze: | OpenAIRE |
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