The carbon dioxide reforming of methane has attracted
attention
from researchers owing to its possibility of both mitigating the hazards
of reactants and producing useful chemical intermediates. In this
framework, the activity of the nickel-based catalysts, supported by
yttria-stabilized zirconia and promoted with holmium oxide (Ho2O3), was assessed in carbon dioxide reforming of
methane at 800 °C. The catalysts were characterized by N2-physisorption, H2 temperature-programmed reduction,
temperature-programmed desorption of CO2, X-ray diffraction,
scanning electron microscopy (SEM) together with energy-dispersive
X-ray spectroscopy, transmission electron microscopy (TEM), and thermogravimetric
analysis (TGA) techniques. The effect of holmium oxide weight percent
loading (0.0, 1.0, 2.0, 3,0, 4.0, and 5.0 wt %) was examined owing
to its impact on the developed catalysts. The optimum loading of Ho2O3 was found to be 4.0 wt %, where the methane
and carbon dioxide conversions were 85 and 91%, respectively. The
nitrogen adsorption–desorption isotherms specified the mesoporous
aspect of the catalysts, while the SEM images displayed a morphology
of agglomerated, porous particles. The TEM images of the spent catalyst
displayed the formation of multiwalled carbon nanotubes. TGA of the
4.0 wt % of Ho2O3 catalyst, experimented over
7-hour time-on-stream, displayed little weight loss (<14.0 wt %)
owing to carbon formation, indicating the good resistance of the catalyst
to carbon accumulation due to the enhancing ability of Ho2O3 and its adjustment of the support.