Catalytic properties of Ni/MWCNT and La-promoted Ni/MWCNT for methanation reaction of carbon dioxide

Abstract

Nickel multiwalled carbon nanotubes (Ni/MWCNT) and lanthanum-promoted Ni/MWCNT were successfully synthesized by impregnation. Methanation of carbon dioxide was used as a probe to evaluate their catalytic performance. N 2-BET, temperature programmed reduction (TPR), X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to study the advantageous effects of La on the structure, surface composition, reduction properties and reaction performance of Ni/MWCNT. It was found that La-promoted Ni/MWCNT catalysts showed better catalytic activity for the reaction than the un-promoted. The addition of La to Ni/MWCNT improves the concentration and dispersion of the active NiO component on the catalyst surface, thus weakening the interaction between support and NiO species, which in turn improves the electron density at the NiO species. As a consequence, the adsorption of reactants was enhanced and the activity improved. Moreover, the sequence in which La was added was also studied in this work. Ni-La/MWCNT, in which La was impregnated onto the MWCNT first, shows better catalytic performance than La-Ni/MWCNT, where the Ni was impregnated first. © Editorial office of Acta Physico-Chimica Sinica.