Metal catalyzed synthesis of carbon nanostructures in an opposed flow methane oxygen flame

• Published in: Combustion and flame Vol. 135; no. 1; pp. 27 - 33
• Main Authors: Saveliev, Alexei V., Merchan-Merchan, Wilson, Kennedy, Lawrence A.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.10.2003; Elsevier Science
• Subjects: Applied sciences; Carbon nanotubes; Combustion of gaseous fuels; Combustion synthesis; Combustion. Flame; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Nano processing; Theoretical studies. Data and constants. Metering; Carbon nanotubes; Nano processing; Combustion synthesis; Methane; Scanning electron microscopy; Transmission electron microscopy; Nanotube; Combustion; Nanostructure; Nickel; Experimental study; Carbon; Supported catalyst
• ISSN: 0010-2180; 1556-2921
• DOI: 10.1016/S0010-2180(03)00142-1

Results of an experimental study on metal-catalyzed synthesis of carbon tubular nanostructures in opposed flow flame are reported. The catalytic support made of Ni-alloy was positioned at the fuel side of the opposed flow flame formed by fuel (96%CH 4+4%C 2H 2) and oxidizer (50%O 2+50%N 2) streams. The electron microscopy studies reveal the presence of highly organized carbonaceous structures with the configurations showing strong dependence on the flame location. Several typical structures were detected. These include: multiwalled nanotubes (MWNT), MWNT bundles, irregular high-density carbon nanofibers, long (up to 0.2 mm) uniform-diameter (∼100 nm) nanofibers, helical regularly coiled tubular nanofibers, and ribbon-like coiled nanofibers with rectangular cross section. Transmission electron microscopy (TEM) studies performed on long nanofibers revealed the presence of highly organized multiple (∼100) graphene layers. These layers are parallel to the nanofiber axis resembling the structure of MWNT. The TEM studies of coiled nanofibers show internal tubular structure and the presence of regular carbon lattice. The well-aligned bundles of nanotubes were examined by TEM showing tight packing of MWNTs with varying inner and outer diameters. The diversity of formed nanomaterials is attributed to the strong variation of flame properties along the flame axis including temperature, hydrocarbon and radical pool. This provides strong selectivity for formation of different nanoforms even without adjustment of catalyst properties.