COLL 441 |
| Dragos Ciuparu, Yuan Chen, Sangyun Lim, Gary L. Haller, and Lisa Pfefferle. Department of Chemical Engineering, Yale University, 9 Hillhouse Ave. ML310, New Haven, CT 06520-8286 |
| A cobalt catalyst atomically dispersed into the silica framework of the MCM-41 mesoporous molecular sieve has been used to grow aligned, uniform diameter single walled carbon nanotubes (SWNT). Carbon yield and SWNT diameter were observed to be highly sensitive to the catalyst pretreatment and nanotube growth reaction conditions. Process variables (pre-reduction temperature, time, reaction temperature, pressure and time) were systematically investigated with the overall objective to achieve large yields of SWNT uniform in diameter without amorphous carbon, multiwall carbon nanotubes or graphite impurities. SWNT diameters were determined by high resolution transmission electron microscopy, Raman and NIR spectroscopy. Product selectivity and SWNT purity were determined both by Raman and temperature programmed oxidation in a thermo-gravimetrical analysis instrument. The optimal synthesis conditions are dependent on the pore size of the catalyst suggesting the mechanism behind the SWNT diameter control is based on the size of the cobalt clusters formed during the synthesis. |
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Symposium in Memory of Arthur W. Adamson
2:00 PM-5:40 PM, Wednesday, March 31, 2004 Marriott -- Orange County 4, Oral
Division of Colloid and Surface Chemistry |