Effect of La, Ce and Nd oxides addition on the activity and stability of Co/MgO catalyst for methane decomposition into CO_x-free H₂ production and carbon nanotubes

Abstract

The influence of lanthanide metals (La, Ce or Nd) addition as a promoter to Co/MgO catalyst was investigated for the “COx-free” hydrogen production via catalytic decomposition of methane (CDM). The catalysts were prepared using impregnation or co-impregnation method with a total metal content of 40 wt%. The characterizations of fresh and used catalysts were carried out by XRD, Raman spectroscopy, BET, TPR, TEM and TGA techniques. It was found that the incorporation of 10% La to 30% Co/MgO has improved the catalytic decomposition activity (∼ 82% hydrogen yield) and stability (220 min) compared to the un-promoted 40% Co/MgO catalyst. On the contrary, the addition of 10% Ce has induced a remarkable inhibition in the catalytic performance (25% at 210 min), where no significant change was observed upon addition of 10% Nd to 30% Co/MgO. The results revealed that the incorporation of La as a promoter induced a suitable strong interaction between MgO support and CoO active metal, enhancing the catalytic activity and stability of the catalyst for methane decomposition reaction. From XRD and TPR analysis, the presence of LaCoO3 phase facilitates the reduction of Co oxide so enhanced the production of Co metallic form which can be referred to its highest activity. TEM images illustrated that the accumulated carbon over all catalysts is multi-walled carbon nanotubes.