CO preferential oxidation on cordierite monoliths coated with Co/CeO2 catalysts

Cordierite monoliths washcoated with Co/CeO2 catalysts prepared from different methods were studied for the CO preferential oxidation reaction. Powder catalysts were also studied for the sake of comparison and in order to select the best formulations to prepare the catalytic coatings. High –Co loaded catalysts resulted in good CO conversions and they showed Co3O4 as the main cobalt containing phase. Consequently, three cordierite – washcoated catalysts were prepared with high Co loadings (ca. 10 wt. % of Co in the catalytic layer). C1 and C2 were obtained by CeO2 washcoating followed by cobalt impregnation. In the first case, Ce oxide particles were obtained from a nitrate solution and in the second, a Nyacol suspension was used. A third sample was prepared (C3) using a slurry of a co-precipitated Co10(CP) catalyst. Monolith C3 showed the best CO conversion, although the difference with the other catalysts was not so evident as the one observed for the powder formulations. The mechanical stability, measured by ultrasound tests, was good for all monolithic catalysts and monolith C1 showed no-deactivation after 100 h of time-on-stream at 190 °C. The structured catalysts prepared were characterized by XRD, TPR, LRS, SEM and XPS, showing that their physical-chemistry features depend on the preparation method and Co loading.