Study of textural properties and nucleation phenomenon in Pd/SiO2, Ag/SiO2 and Cu/SiO2 cogelled xerogel catalysts
| Autor: | Stéphanie Lambert, Benoıˆt Heinrichs, Jean-Paul Pirard, Christelle Alié |
|---|---|
| Rok vydání: | 2004 |
| Předmět: |
Materials science
Kinetics Dispersity Nucleation Mineralogy Microporous material Condensed Matter Physics Electronic Optical and Magnetic Materials Catalysis Metal Chemical engineering visual_art Materials Chemistry Ceramics and Composites visual_art.visual_art_medium Crystallite Texture (crystalline) |
| Zdroj: | Journal of Non-Crystalline Solids. 342:70-81 |
| ISSN: | 0022-3093 |
| Popis: | Pd/SiO2, Ag/SiO2 and Cu/SiO2 xerogel catalysts have been synthesized by cogelation of tetraethoxysilane (TEOS) and chelates of Pd, Ag and Cu with 3-(2-aminoethylamino)propyltrimethoxysilane (EDAS). The resulting materials are composed of completely accessible metallic crystallites with a diameter of about 3 nm, located inside silica particles exhibiting a monodisperse microporous distribution centered on a pore width of about 0.8 nm. Voids between silica particles and between aggregates of silica particles constitute the material meso- and macroporous texture. The EDAS/TEOS ratio is the main operating variable to tailor the material morphology. When the EDAS/TEOS ratio decreases, metallic particle size decreases, whereas silica particle size increases. Thus the meso- and macropores between silica particles are larger. So the total pore volume can reach 5 cm3/g when the EDAS/TEOS ratio decreases. The remarkable morphology of these materials can be explained by the rule in which the EDAS–metal complex acts as a nucleation agent in the formation of silica particles. A nucleation mechanism by EDAS–metal complex based on mass equations and the nuclei formation kinetics allows fitting the entire results. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect