Characterization of Single-Walled Carbon Nanotubes (SWNTs) Produced by CO Disproportionation on Co−Mo Catalysts

Abstract

The disproportionation of CO over Co-Mo/SiO 2 catalysts with low Co/Mo ratios results in a high selectivity to single-walled carbon nanotubes (SWNTs) when the reaction is conducted between 700 and 950 °C in a flow of pure CO at a total pressure between 1 and 5 atm. A detailed characterization involving Raman spectroscopy, temperature-programmed oxidation (TPO), and transmission electron microscopy (TEM) shows that the product of this process has a high concentration of SWNTs. Depending on the temperature of operation, the selectivity and nanotube diameter can be varied.

Chemical kinetic considerations for postflame synthesis of carbon nanotubes in premixed flames using a support catalyst

“…CO is a stable compound and requires up to 5 eV of energy to initiate its disproportionation (Boudouard reaction) [32][33][34]. CO has been used as the primary source of carbon for CNT synthesis in other manufacturing processes [35,36]. Many of these methods require either high pressures or an external source of energy to initiate this reaction.…”

Cold wall CVD generation of single-walled carbon nanotubes and in situ Raman scattering measurements of the growth stage

“…The generation technique of SWNTs has since been developed by demands for specimens with sufficient amount and quality. Followed by the landmark establishment of the synthesis method in macroscopic amounts by laser-furnace [3] and arc-discharge [4] methods, several techniques employing the CVD approach [5][6][7][8][9][10][11][12][13] have been proposed for improved efficiency or productivity in the bulk synthesis of SWNTs. At present, CVD approaches, including the high-pressure CO (HiPco) technique [6,7], have become dominant for the mass production of SWNTs.…”

Multifunctional Catalysts for Singlewall Carbon Nanotube Synthesis

“…34,49 Their findings indicate that monometallic catalysts (Co, Mo, or W) are much less effective than bi-MNPs because excessive amount of W or Mo help isolate small Co oxide nanoparticles for the synthesis of SWNTs. Even though their synthetic conditions were different from either the Ni/Co system in laser vaporization experiment or the HiPCO method in which Fe or other catalysts are also produced in situ and in space, 14 the substrate effect was found negligible because the authors did not find any Si in the nanoparticles.…”