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 Cα which is easily gasified by H2 and also participates in redox reactions with cerium oxides, and a relatively non-reactive Cβ which is only removed by O2 and does not participate in the redox cycle. A dual-site Langmuir–Hinshelwood mechanism for the reaction was also proposed.