Syngas production via combined steam and carbon dioxide reforming of methane over Ni–Ce/MgAl2O4 catalysts with enhanced coke resistance

Abstract

A Ni–Ce/MgAl2O4 catalyst was prepared by the co-impregnation method by adjusting the Ce/Ni ratio in a range of 0.0–1.0 for the combined steam and carbon dioxide reforming of methane (CSCRM). The characterization as to surface area, metal dispersion, NiO crystallite size as well as reduction temperature and basicity of prepared catalysts was analyzed by BET, H2-chemisroption, XRD, TPR and CO2-TPD. The used catalysts were collected to investigate the coke formation and surface characteristics through SEM, TGA, XPS and Raman analysis. The Ce addition to Ni/MgAl2O4 catalyst has significant effects on the NiO crystallite size, metal dispersion and reduction degree. The Ni–Ce/MgAl2O4 catalyst with the Ce/Ni ratio of 0.25 showed the smallest NiO crystallite size of 8.3nm and the highest metal dispersion of 4.91%. Meanwhile, in the Ni/MgAl2O4 (Ce/Ni=0) catalyst, the NiO crystallite size was found to be as large as 11.0nm and showed a low metal dispersion of 3.49%. The Ni–Ce/MgAl2O4 (Ce/Ni=0.25) catalyst shows the highest activity and coke resistance in CSCRM due to the improvement of metal dispersion, excellent reducibility as well as effective surface oxygen transfer as evidenced by XPS results.