Synthesis of nanocrystalline gold–carbon nanotube composites and evaluation of their sorption and catalytic properties

Gold particles the size of nanometer scale supported on various substrates have gained enormous attention in the surface science and catalysis community. The more interesting application is the low temperature oxidation of CO. In the current work we proceed to the doping of commercial single carbon nanotubes with Au nanoparticles. The samples were characterized by X-ray diffraction and TEM. The characteristic XRD peaks denote the presence of the noble metal nanoparticles as well as a rough approximation of crystallite size and structure. TEM images gave us a clue about the size, the shape and dispersion of these particles on carbon nanotube surface. Sorption experiments of CO, CO2 and O2 at different temperatures ranging between 273 and 323 K were conducted to both carbon nanotubes and doped carbon nanotubes to elucidate the special interaction of gases with the noble metal nanoparticles and examine the role of the support in the conversion efficiency of CO. The activity of supported gold for CO oxidation in low temperatures was investigated by catalytic experiments in a specially developed continuous flow reactor, involving a packed bed of doped nanotubes. The reactor was interfaced with a gas chromatograph equipped with thermal conductivity detector and gas sampling valve.