Activity of Low-Co/Al-Ratio Mixed Oxides Derived from Co-LDH Precursors in the Flameless Combustion of Methane

Co-LDH or Co-LDH-Gibbsite precursors were prepared by wetness impregnation and co-precipitation of 9% CoII. Mixed oxides obtained from the calcination at 800°C were characterized by XRD, FTIR and SEM-EDS. XRD showed only spinel and periclase crystalline phases. The activity of total methane combustion for five mixed oxides was tested at atmospheric pressure between 350°C and 600°C. The material obtained from the Co-LDH-Gibbsite precursor ignites methane at T<350°C and completes the combustion at 565°C. The FTIR and SEM-EDS of the most active materials indicate that low Co/Al ratios facilitate the formation of surface cobalt spinel, thus improving methane combustion over mixed oxides.