Kinetic study of methane CO2 reforming on Co-Ni/Al2O3 and Ce-Co-Ni/Al2O3 catalysts

The performance of Ce-promoted and undoped 5Co-15Ni/Al2O3 catalysts for the dry reforming of CH4 has been investigated in a fixed-bed reactor. Although addition of Ce (2.5 wt%) significantly reduced carbon deposition by up to 50%, there was neither marked improvement in CH4 reaction rate (< 5% increase) nor a significant change in activation energy. The increased carbon resistance of the Ce-promoted catalyst was attributed to equilibrium between stable multiple oxidation states of the Ce ion during the reaction. TPR-TPO of used catalysts revealed the existence of two types of carbon species-reactive C-alpha which is easily gasified by H-2 and also participates in redox reactions with cerium oxides, and a relatively non-reactive C-beta which is only removed by O-2 and does not participate in the redox cycle. A dual-site Langmuir-Hinshelwood mechanism for the reaction was also proposed. (C) 2010 Elsevier B.V. All rights reserved.