High yiel vapor phase deposition method for large scale sing walled carbon nanotube preparation

Abstract

An improved vapor phase deposition method for preparation of single walled carbon nanotubes on an aerogel supported metal catalyst. The total yield of SWCNTs often is at least about 100%, based the weight of the catalyst, for a reaction time of at least about 30 minutes.

Description

[0002] The present invention relates, in general, to a vapor phase deposition method for the preparation of single walled carbon nanotubes, where the method employs a metal catalyst on a support. More particularly, the present invention relates to an improved method where the support comprises an aerogel, such as an Al.sub.2O.sub.3 aerogel or an Al.sub.2O.sub.3 / SiO.sub.2 aerogel, as compared to prior art methods that employed supports that are powders. The improved method results in far higher yields of single walled carbon nanotubes than the prior art methods.1 Abbreviations ASB aluminum tri-sec-butoxide AFM atomic force microscope (acac).sub.2 bis(acetylacetonato) cm centimeter C centrigrade CVD chemical vapor deposition EtOH ethanol g gram kg kilogram kV kilovolt m meter ml milliliter MW molecular weight MWCNT multi-walled carbon nanotube nm nanometer psi pounds per square inch SEM scanning electron microscope SWCNT single walled carbon nanotube sccm standard cubic centimeter per...

AI Technical Summary

Benefits of technology

[0017] Hence, it is an advantage that this inventive discovery affords a way to prepare SWCNT materials on a large scale, i.e., industrial scale, with low cost.

[0022] The present invention provides single walled carbon nanotubes using a novel vapor phase method in which a particular catalyst / support is employed in deposition of a carbon-containing compound. In a preferred embodiment, the present invention provides a dramatic increase in the yield of single walled carbon nanotubes as compared to the prior art method that uses powder for a support.

Problems solved by technology

Although carbon nanotube materials possess many unique and technically important properties, lack of a way to produce a sufficient amount of materials has limited not only the study of the fundamental properties but also the development of more practical applications.

However, both techniques suffer from the problem that it is hard to increase the production volume of the nanotube materials from laboratory scale to industrial scale.

Hence, although the report for ethylene and the report for benzene each mentions SWCNTs, they have the drawback that they are always mixed with a substantial amount of MWCNTs.

However, the reported yield of the methane CVD method is low, with the best results so far giving a total yield of 40% based on the weight of catalyst for a reaction time of 10 to 45 minutes, where the catalyst was supported on Al.sub.2O.sub.3 powder or on Al.sub.2O.sub.3 / SiO.sub.2 powder and the catalyst / support had a surface area of about 100 m.sup.2 / g.

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