Thermodynamic study of carbon nanotube production from greenhouse gases during syngas synthesis
Date
2010-07-26T08:27:06Z
Authors
Maphutha, Selby Kwena
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Abstract
Global warming has become a major topic for the public in recent years and many institutions
and industries have been pushed to find a ‘cure’ for it. The most wildly known culprit for
global warming is carbon dioxide and several methods for the treatment of this gas have been
proposed. There is thermal decomposition, capturing methods and chemical decomposition.
This study looks at the conversion of carbon dioxide and another greenhouse gas, methane,
into carbon nanotubes and syngas (hydrogen and carbon monoxide), which is a precursor to
the petroleum compounds in the Fischer-Tropsch process. The study was done
experimentally by running a CO2\CH4 mixture through a CVD reactor, at temperatures
ranging from 650 to 950oC, and two catalysts (a lanthanum-nickel alloy and a mischmetalnickel
alloy separately). Theoretically, the thermodynamics of this process were done at
temperatures ranging from 600 to 1500 K. The products from the experiment were analysed
using a Transmission electron microscope (both normal and high resolution), Raman
spectroscopy and Gas chromatography. Using the proposed catalysts, the carbon dioxide and
the methane were decomposed, forming carbon nanofibers and carbon nanotubes as shown
by the transmission electron microscope images. The carbon nanofibers and nanotubes
became less defined and generally fewer in number as the temperature increased. The
thermodynamics also showed that the carbon decreased and the syngas increased as the
temperature increased. The Gas chromatography showed that there was syngas that was
produced during the experimental process. The mischmetal-nickel alloy proved to convert
more of the greenhouse gasses into syngas than the lanthanum-nickel alloy.