Zirconia-supported cobalt as a catalyst for methane combustion

Cobalt-supported catalysts were prepared using two different techniques: atomic layer epitaxy (ALE) and wet impregnation. Cobalt and lanthanum acetylacetonates were used and the solvents employed were either anhydrous THF or isobutyl alcohol. ZrO2 and La2O3/ZrO2 (lanthanum-doped ZrO2) were used as supports and La2O3 as reference. The most active catalysts in the 770-970 K range were those in which cobalt was incorporated using the ALE technique over ZrO2 or La2O3/ZrO2, The tested solids were characterized by XRD, TPR, and XPS, The features that differentiate good from poor catalysts are the following: good cobalt dispersion, the presence of surface Co2+, a low-temperature TPR peak, the absence of bulk carbonates, and the limited amount of surface carbonates. These results are discussed in terms of the current literature. (C) 2001 Academic Press.