Carbon nanotubes and nanocrystals in methane combustion and the environmental implications

• Published in: Journal of materials science 2004-03, Vol.39 (6), p.2199-2204
• Main Authors: MURR, L. E, BANG, J. J, LOPEZ, D. A, GUERRERO, P. A, ESQUIVEL, E. V, CHOUDHURI, A. R, SUBRAMANYA, M, MORANDI, M, HOLIAN, A
• Format: Article
• Language: English
• Subjects: Carbon nanotubes; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Nanocrystalline materials; Nanocrystals; Nanoscale materials and structures: fabrication and characterization; Nanotubes; Physics
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1023/B:JMSC.0000017787.53545.b7

Current methods involving aerosol synthesis of carbon nanotubes include arc discharge, laser ablation, and catalytic/decomposition growth for the production of single and multi-walled nanotubes of carbon. Common to these approaches is the generation of particles in the presence of a reactive hydrocarbon species at elevated temperatures (600-1200DGC). In contrast, ordinary combustion flames can naturally form carbon nanoparticles, primarily carbon blacks. Such flames represent a complex chemical environment characterized by steep temperature gradients and concentrations of species. Catalytic decomposition of acetylene (C2H2) and methane (CH4) in the presence of an iron catalyst has been a common methodology for carbon nanotube production. In this letter, the production of a range of carbon nanotubes and nanocrystal particulates, primarily aggregates, by near optimal combustion of pure methane (99.5%) in a laminar methane-air co-flow flame, and evidence for the presence of these carbon nanotubes and nanocrystals in atmospheric aerosols is reported.