I&EC 103 |
| Katherine E.H. Gilbert1, Michael J. Heben2, Anne C. Dillon2, Philip A. Parilla2, Jeff L. Alleman2, Kim M. Jones2, J. Douglas Way1, Robert M. Baldwin1, and Thomas Gennett3. (1) Department of Chemical Engineering, Colorado School of Mines, 1500 Illinois Street, Golden, CO 80401, (2) Center for Basic Sciences, National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, CO 80305, (3) NanoPower Research Laboratories, Rochester Institute of Technology, 85 Lomb Memorial Drive, Rochester, NY 14623 |
| The potential applications for carbon single-wall nanotubes (SWNTs) are widespread because of their unique gas adsorption, electronic and mechanical characteristics. However, it has become apparent that in order to exploit these characteristics, SWNTs must be free of metal and carbonaceous impurities. Previously, we reported a simple purification process for laser-synthesized materials (that may result in > 98 wt% pure SWNTs). However, in many cases the laser-synthesis process of SWNTs generates graphite encapsulated catalyst metals that are difficult to eliminate, and the simple purification process does not result in high purity materials. More aggressive acid treatments destroy nanotubes resulting in low yields. This work describes a unique process that utilizes a gas-phase oxidation of nanotube material. At temperatures ranging between 800 and 1000 C, the carbon coating surrounding the metal particles in as-produced nanotube samples or as-produced nanotube samples after refluxing in nitric acid, is oxidized in flowing carbon dioxide. XRD analysis indicates this effectively oxidizes the “graphitic” encapsulated metal particles. The selective oxidization allows for a more effective and facile acid dissolution of the metals. The final yields of nanotubes are still approximately 30% based upon the original mass sample, and the percent by weight of metal less than 1% is easily achieved. Also, Raman analysis indicates that with increasing oxidation temperature smaller tubes are consumed. |
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Purification, Separation, and Characterization of Single-Walled Carbon Nanotubes (SWNT's) (sponsored by Advanced Materials & Nanotechnology Subdivision)
8:15 AM-11:55 AM, Tuesday, March 30, 2004 Marriott -- Orange County 2, Oral
Division of Industrial and Engineering Chemistry |