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News & Events

FOR IMMEDIATE RELEASE
AUGUST 2005
WESTWOOD, MASSACHUSETTS

Nano-C: Cost-efficient and Scalable Combustion Synthesis of High-Quality Single-walled Carbon Nanotubes

General Description
Founded in 2001, Nano-C, Inc. has been bringing to market maturity large scale production of fullerenic materials by controlled combustion of hydrocarbons. Initially developed in the Department of Chemical Engineering of the Massachusetts Institute of Technology, this technology enables the synthesis of spherical fullerenes (C₆₀, C₇₀, ?, C₈₄, ?), fullerenic carbon nanostructures and single-walled carbon nanotubes (see Fig. 1) at prices consistent with the use of fullerenic materials in commercial applications. Schematic representations of C₆₀ and C₇₀ fullerenes, single-walled carbon nanotubes as well as a transmission electron microscopy (TEM) image of fullerenic carbon nanostructures ("fullerene black") are given in Fig. 1.

Identity and characteristics of the combustion-generated material can be determined by control of the operating conditions such as the type of the fuel, the fuel-oxygen ratio, pressure, dilution with inert gas and residence time.

Synthesis of single-walled carbon nanotubes
The most recent development of Nano-C's proprietary technology allows for the selective synthesis of high-quality single-walled carbon nanotubes. Catalyst precursor is supplied with the initial fresh gas mixture and converted to active catalyst particles in the flame environment. Single-walled carbon nanotubes are formed from carbon-containing species and subsequently collected from the exhaust gas.

The major characteristics of Nano-C's process are:

• Inexpensive hydrocarbons such as methane or natural gas are converted to single- walled carbon nanotubes by premixed combustion.
• The process is exothermic, i.e., no external energy supply is required. Excess energy can be recovered for further use.
• Feed of catalyst precursor premixed with the initial hydrocarbon/oxygen mixture allows for uninterrupted operation and recovery of the resulting single-walled carbon nanotubes from the exhaust gas by filtration.
• The distribution of the tube diameters is nearly monodisperse as shown by the sharp single radial breathing mode (RBM) peak in Raman spectra measured on material synthesized at Nano-C (Fig. 2). A direct correlation between the location of the RBM peak and the tube diameter has been reported in the literature. A RBM at 240 cm^-1 (Fig. 2) corresponds to a tube diameter of approximately 1 nm.
• Further analysis of the G-band of the Raman spectra, located at approximately 1590 cm^-1 and reflecting tangential vibrations along the nanotubes, indicates a relatively pronounced metallic character of Nano-C's material.
• The low intensity of the D-band, characteristic for defects breaking the symmetry of the graphene sheet, is confirming the high quality of Nano-C's single-walled carbon nanotubes.
• Single-walled carbon nanotubes have been visualized by means of scanning electron microscopy (SEM), shown in Fig. 3, and transmission electron microscopy (TEM) (see Fig. 4). While SEM provides an overall picture of the material composition, detailed analysis at higher resolution by means of TEM confirms the absence of any contamination with multi-walled carbon nanotubes.

What Nano-C has to offer
Nano-C is currently pursuing the further optimization of its proprietary combustion-based nanotube synthesis technology. Control of all major process parameters, i.e., fuel-to-oxygen ratio, pressure, temperature, catalyst precursor concentration and residence time allows targeted synthesis of carbon nanotubes with specific characteristics. The capacity of the reactor operating in Nano-C's facilities in Westwood, MA is sufficient for the synthesis of sample quantities for our customers and partners. Taking advantage of Nano-C's experience in the production of spherical fullerenes (C₆₀, C₇₀, ? C₈₄, ?), we are prepared for scale-up in a short time frame. Nano-C's value proposition includes:

• Joint development activities with end users of carbon nanotubes. Nano-C works with its partners on the selective synthesis of carbon nanotubes suitable for specific applications. Nano-C can produce material during the development and early commercialization periods and we will assist in establishing reliable and inexpensive supply of high-quality carbon nanotubes at an industrial scale.
• Nano-C is prepared to license its technology. Different options such as licensing for selected market segments or geographic areas are available. Nano-C will provide the necessary technical assistance to ensure a fast and cost-efficient start-up of a reliable operation.