Comparison of catalytic performance and coking resistant behaviors of cobalt- and nickel based catalyst with different Co/Ce and Ni/Ce molar ratio under SRE conditions

A series of Co-xCe/CeO2 and Ni-xCe/CeO2 catalysts with different ceria amount introduced from Ce (NO3)(3) x 6H(2)O precursor, corresponding to Ce/Co(Ni) molar ratio from 0 to 1 were prepared by impregnation method. Among the tested catalysts, Co-0.1Ce/CeO2 and Ni-0.1Ce/CeO2 samples exhibited the smallest metal crystallites size, the strongest metal-support interaction, the best catalytic performance and the strongest resistance toward carbon deposition. Only an introduction of small amount of ceria from Ce(NO3)(3) x 6H(2)O precursor led to an increase in the number of active sites for breaking C-C and C-H bonds. Too high Ce/Co molar ratio caused rapid deactivation of cobalt-based catalysts because of faster coverage of active sites by encapsulating carbon. Whereas too high Ce/Ni molar ratio generated the thick and long carbon filamentous deposits causing the nickel-based catalysts deactivation including not only the coverage of nickel species by carbon but also limitation of the contact of reactants with nickel species.