Role of CO2 methanation into the kinetics of preferential CO oxidation on Cu/Co3O4

In the present study, cobalt oxide (Co3O4) and Cu substituted Co3O4 were synthesized using sonochemical method. The role of Cu substitution was studied for CO oxidation in absence of H-2 as well as in H-2 rich conditions (PrOx). The synthesized catalysts were characterized by XRD, XPS, TEM and BET. The role of side reactions such as H-2 oxidation and CO2 methanation in inhibiting the CO oxidation reaction were discussed. H-2 - TPR and in situ FTIR were conducted to understand the reducible nature of the support and reaction mechanism. The intermediate species such as carbonates, bicarbonates, formates play an important role for CO oxidation under H-2 rich conditions. Further, the utilization of atomic hydrogen by surface CO2 species, enhanced the methane formation. A detailed reaction mechanism was proposed for both CO oxidation and PrOx conditions with the insights obtained from in situ FTIR. 3% Cu/Co3O4 showed high stability for CO oxidation under hydrogen rich conditions for 50 h at 170 degrees C as well as in methanation prone region at 200 degrees C.