The present work addresses the influence of the support on the catalytic behavior of\nCo3O4-based catalysts in the combustion of lean methane present in the exhaust gases from natural\ngas vehicular engines. Three different supports were selected, namely Gamma-alumina, magnesia and\nceria and the corresponding catalysts were loaded with a nominal cobalt content of 30 wt. %.\nThe samples were characterized by N2 physisorption, wavelength dispersive X-ray fluorescence\n(WDXRF), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and\ntemperature-programmed reduction with hydrogen and methane. The performance was negatively\ninfluenced by a strong cobalt-support interaction, which in turn reduced the amount of active cobalt\nspecies as Co3O4. Hence, when alumina or magnesia supports were employed, the formation of\nCoAl2O4 or Co-Mg mixed oxides, respectively, with a low reducibility was evident, while ceria\nshowed a lower affinity for deposited cobalt and this remained essentially as Co3O4. Furthermore,\nthe observed partial insertion of Ce into the Co3O4 lattice played a beneficial role in promoting\nthe oxygen mobility at low temperatures and consequently the catalytic activity. This catalyst also\nexhibited a good thermal stability while the presence of water vapor in the feedstream induced a\npartial inhibition, which was found to be completely reversible.
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