Effect of Co-MCM-41 Conversion to Cobalt Silicate for Catalytic Growth of Single Wall Carbon Nanotubes
| Autor: | Dragos Ciuparu, and Lisa Pfefferle, Gary L. Haller, Yuan Chen, Sangyun Lim |
|---|---|
| Rok vydání: | 2004 |
| Předmět: |
inorganic chemicals
Materials science Inorganic chemistry chemistry.chemical_element Carbon nanotube Silicate Surfaces Coatings and Films Catalysis law.invention chemistry.chemical_compound chemistry Amorphous carbon MCM-41 law Materials Chemistry Orthosilicate Graphite Physical and Theoretical Chemistry Cobalt |
| Zdroj: | The Journal of Physical Chemistry B. 108:20095-20101 |
| ISSN: | 1520-5207 1520-6106 |
| Popis: | Cobalt silicate was studied as a model catalyst to seek an understanding of why Co-MCM-41 catalyst is not active for single wall carbon nanotubes (SWNT) upon treatment at high temperature. Cobalt orthosilicate was formed during high-temperature pretreatment of Co-MCM-41 (at 900 °C) in an oxidizing environment. Cobalt silicate did not produce any carbon species during the first reaction cycle because the high thermal stability of cobalt silicate did not result in sufficient metallic Co clusters responsible for carbon dissociation in CO disproportionation. With repeated reaction cycles, however, undesirable carbon species, i.e., amorphous carbon and graphite, were produced resulting from larger metallic cobalt clusters formed at the high reduction temperature and without the confinement and/or anchoring of the MCM-41 matrix. These relatively large clusters do not catalyze the growth of SWNT. |
| Databáze: | OpenAIRE |
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