The Penn State Research Foundation

Honda Giken Kogyo Kabushiki Kaisha

Bhabendra K Pradhan

Avetik R Harutyunyan

Peter C Eklund

Yoshiya Fujiwara

Hajime Goto

The present invention is directed towards a method of producing single wall carbon nanotubes which comprises providing a catalyst comprising an alumina support and a component selected from the group consisting of reduced Fe, reduced Fe/Mo, Fe oxide, and Fe/Mo oxide, and growing, in an inert atmosphere, single wall carbon nanotubes by passing a gas comprising methane over the catalyst at a temperature and for a time sufficient to grow single wall carbon nanotubes. The invention is also directed towards a single wall carbon nanotube produced by such a method. The invention is also directed towards a catalyst for producing SWNTs, wherein the catalyst comprises an alumina support and a component selected from the group consisting of reduced Fe, reduced Fe/Mo, Fe oxide, and Fe/Mo oxide.

Method for low temperature synthesis of single wall carbon nanotubes

Disclosed are methods of purifying mixtures comprising nanofibers and/or nanotubes and residual catalyst particles that are covered by outer layers of the nanotube or nanofiber material. The mixtures are exposed to electromagnetic radiation, which induces localized heating in the residual catalyst particles. The localized heating creates breaches in the outer layers. Thereafter, the residual catalyst particles may be removed under relatively mild conditions that do not significantly affect the structural integrity of the nanotubes or nanofibers. The methods of the invention have been used to particular advantage in the purification of single wall carbon nanotubes (SWNTs) synthesized using metal catalysts. For these SWNTs, microwave radiation is preferably used to induce the localized heating, the outer layers are preferably removed at least in part by carrying out the localized heating under air, and the residual catalyst may be removed by exposure to relatively dilute aqueous acid.

Method of purifying nanotubes and nanofibers using electromagnetic radiation

Carbon fiber/tubes are prepared by pyrolyzing a catalyst system that contains one or more diluents to facilitate control of the diameter of the formed carbon fiber/tube.

Method of forming carbon fibers

Carbon structures, e.g. carbon nano-fibers, suitable for absorbing hydrogen at low pressures and low temperatures are produced by a selective oxidation and/or acid reflux process. The process includes heating an impure mixture containing a crystalline form of carbon in the presence of an oxidizing gas at a temperature and time sufficient to selectively oxidize and remove a substantial amount of any amorphous carbon impurities from the mixture. Metal containing impurities can be removed from the mixture by exposing the desired carbon and accompanying impurities to an acid to produce a carbon fiber that is substantially free of both non-fiber carbon impurities and metal impurities. Another aspect of the present invention includes purified carbon structures that can store hydrogen at low pressures and temperatures.

Growing community of inventors

State College, PA, United States of America

Bhabendra K Pradhan