Abstract: Methods and processes for synthesizing single-wall carbon nanotubes are provided. A carbon precursor gas is contacted with metal catalysts deposited on a support material. The metal catalysts are preferably nanoparticles having diameters less than about 3 nm. The reaction temperature is selected such that it is near the eutectic point of the mixture of metal catalyst particles and carbon. Further, the rate at which hydrocarbons are fed into the reactor is equivalent to the rate at which the hydrocarbons react for given synthesis temperature. The methods produce carbon single-walled nanotubes having longer lengths.

Abstract: The present disclosure is directed to a method of producing metallic single-wall carbon nanotubes by treatment of carbon nanotube producing catalysts to obtain the desired catalyst particle size to produce predominantly metallic single wall carbon nanotubes. The treatment of the carbon nanotube producing catalyst particles involves contacting the catalyst particles with a mixture of an inert gas, like He, a reductant, such as H2, and an adsorbate, like water, at an elevated temperature range, for example, at 500° C. to 860° C., for a sufficient time to obtain the catalyst particle size. In some of the present methods, the preferential growth of nanotubes with metallic conductivity of up to 91% has been demonstrated.

Abstract: Methods and processes for synthesizing high quality carbon single-walled nanotubes (SWNTs) are provided. The method provides the means for optimization of amount of carbon precursor and transport gas per unit weight of catalyst. Efficiencies of about 20% can be achieved when contacting the catalyst deposited on a support with a carbon precursor gas with a flow rates of about 4.2×10?3 mol CH4/sec·g (Fe) at 780 ° C. Hydrocarbon flow rates of about 1.7 10?2 mol CH4/sec·g (Fe) and higher result in faster carbon SWNTs growth with improved quality. Slower rates of carbon atoms supply (˜4.5×1020 C atoms/s·g Fe or 6.4×10?4 mol CH4/sec·g (Fe)) result in the formation of more defective nanotubes.

Abstract: Methods and processes for synthesizing high quality carbon single-walled nanotubes (SWNTs) are provided. A carbon precursor gas at reduced concentration (pressure) is contacted with a catalyst deposited on a support and at temperature about 10° C. above the SWNT synthesis onset temperature, but below the thermal decomposition temperature of the carbon precursor gas for given growth conditions. The concentration (pressure) of the carbon precursor gas can be controlled by reducing the total pressure of the gas, or by diluting with an inert carrier gas, or both. The methods produce SWNTs with the ratio of G-band to D-band in Raman spectra (IG:ID) of about 5 to about 200.

Abstract: Methods and processes for preparing interconnected carbon single-walled nanotubes (SWNTs) are disclosed. The SWNTs soot, synthesized by any one of the art methods, is heated to less than about 1250° C. in flowing dry air using the electrical field (E) component of microwave energy. The tubes of the SWNTs thus treated become welded and interconnected.

Abstract: Method and processes for synthesizing single-wall carbon nanotubes is provided. A carbon precursor gas is contacted with metal catalysts deposited on a support material. The metal catalysts are preferably nanoparticles having diameters less than about 50 nm. The reaction temperature is selected such that it is near the eutectic point of the mixture of metal catalyst particles and carbon.

Abstract: An apparatus for the production of elongated carbonaceous article includes a chamber having at least one heating element, a catalyst and a device for generating a magnetic field in proximity to or around the catalyst. In operation, a carbon-containing precursor is introduced to the chamber to contact the catalyst with a sufficient amount of heat to cause the deposition of carbon on the catalyst. Continual deposition of carbon over time forms elongated carbon structures, such as carbon fibers and carbon nanotubes. By operating the device to magnetically confine the catalyst during the formation of the carbon structures, migration of catalyst is reduced or prevented thereby minimizing contaminants in the produced products and improving the useful life of the catalyst.

Abstract: An apparatus for the production of elongated carbonaceous article includes a chamber having at least one heating element, a catalyst and a device for generating a magnetic field in proximity to or around the catalyst. In operation, a carbon-containing precursor is introduced to the chamber to contact the catalyst with a sufficient amount of heat to cause the deposition of carbon on the catalyst. Continual deposition of carbon over time forms elongated carbon structures, such as carbon fibers and carbon nanotubes. By operating the device to magnetically confine the catalyst during the formation of the carbon structures, migration of catalyst is reduced or prevented thereby minimizing contaminants in the produced products and improving the useful life of the catalyst.