Effect of preparation methods on the catalytic performance of Ni-Al₂O₃ for CO₂-CH₄ reforming

To investigate the catalytic performance of nickel-based catalysts for carbon dioxide reforming of methane, four samples, SCM, IMP, T310 and HTP, with same contents of Ni were prepared by solution combustion method, incipient-wetness impregnation method, colloid mill circulating impregnation method and hydrothermal-precipitation method. The catalytic performance was tested at 800 ℃. The samples were characterized with ICP-AES, N₂ absorption-desorption method, XRD, H₂-TPR and TEM techniques. It was shown that the preparation methods had significant effects on the catalytic performance. The HTP and T310 samples had larger specific surface area, 190.83 m²/g and 182.21 m²/g respectively, which could provide more active sites and improve the activity (the initial conversion of CH₄ and CO₂ of HTP was up to 85.15% and 90.84%). The reduction peak area of NiAl₂O₄ of the catalysts prepared by solution combustion method and incipient-wetness impregnation method was higher than 90% of the total reduction area, indicating that these catalysts had more small Ni size particles and better stability after reduction (the conversion of CH₄ for SCM and IMP was higher than that of HTP and T310 after 50 h experiment, and was up to 50% after 100 h reaction). Hence, the mojor reason for improving the activity and stability of catalyst would be the size of Ni particles and its resistance to sintering.