Study of carbon dioxide reforming of methane over bimetallic Ni-Cr/yttria-doped ceria catalysts

[[abstract]]©2003 Elsevier - Carbon dioxide reforming of methane was studied over Ni-Cr/yttria-doped ceria (YDC) with various nickel and chromium compositions to seek insights into the activity and deactivation behaviors of the catalysts, as well as into the effects brought about by chromium. The activity of Ni/YDC for the reforming reaction is enhanced compared with that of Ni/γ-Al2O 3, presumably due to the synergistic effect of nickel and surface oxygen vacancies of YDC. It was found that, when YDC was calcined at higher temperatures, both BET surface area and the number of surface oxygen vacancies declined substantially. This made the remaining surface oxygen vacancies more susceptible to be covered and, thereby, affected the activity and coking resistivity of Ni-Cr/YDC catalysts during reforming. For YDC-supported nickel catalysts which possess surface oxygen vacancies intrinsically, the activity enhanced by Cr due to better metallic dispersion is not as high as that resulting from the metal-support synergism, and is offset by the coverage of surface oxygen vacancies by Cr. Although the chromium addition is beneficial to the dilution of the ensembles of Ni atoms and to the stability of nickel catalysts, supports would play an important role in the stability of the Ni-Cr catalysts. The benefit of Cr addition is inadequate to the stability of nickel-based catalysts with low surface-area supports. The H2/CO ratios agree well with the results of activity and deactivation behaviors of catalysts.[[fileno]]2020122010007[[department]]化學工程學