Promotional effect of alkaline earth over Ni-La2O3 catalyst for CO2 reforming of CH4: Role of surface oxygen species on H2 production and carbon suppression

Alkaline earth elements (Mg, Ca and Sr) on Ni-La₂O₃ catalyst have been investigated as promoters for syngas production from dry CO₂ reforming of methane (DRM). The catalysis results of DRM performance at 600 °C show that the Sr-doped Ni-La₂O₃ catalyst not only yields the highest CH₄ and CO₂ conversions (∼78% and ∼60%) and highest H₂ production (∼42% by vol.) but also has the lowest carbon deposition over the catalyst surface. The XPS, O₂-TPD, H₂-TPR and FTIR results show that the excellent performance over the Sr-doped Ni-La₂O₃ catalyst is attributed to the presence of a high amount of lattice oxygen surface species which promotes C-H activation in DRM reaction, resulting in high H₂ production. Moreover, these surface oxygen species on the Ni-SDL catalyst can adsorb CO₂ molecules to form bidentate carbonate species, which can then react with the surface carbon species formed during DRM, resulting in higher CO₂ conversion and lower carbon formation.