Cobalt-Based Catalysts for CO Preferential Oxidation

LETICIA E. GÓMEZ; ALICIA V. BOIX

Cobalt Compounds and Applications

Intech Open (Open Access books)

Lugar: Londres; Año: 2019;

In this work, catalysts based on cobalt supported on ZrO2 and CeO2 andCoCeMnOx were studied for the CO preferential oxidation (COPrOx) in hydrogenrichstream able to feed fuel cells. Among them, the CoCeMnOx formulationshowed the highest CO conversion at low temperatures, while the cobalt oxidesupported on ceria presented the best selectivity toward CO2. The Co3O4 spinel wasthe active phase for the CO preferential oxidation detected in all catalysts. However,the CoOx-CeO2 and CoCeMnOx catalysts resulted more active than cobalt oxidesupported on zirconia. The presence of ceria close to cobalt species promotes theredox properties and enhances the catalytic activity. In the CoCeMnOx catalystprepared by coprecipitation, the incorporation of Mn represented an additionalpositive effect. The presence of Mn promoted the reoxidation of Co2+ to Co3+ and,consequently, the activity increased at low temperature. By X-ray diffraction(XRD) of CoOx-ZrO2 and the CoOx-CeO2 catalysts, the Co3O4 spinel and ZrO2 orCeO2 were identified in agreement with laser-Raman spectra. At the same time,the CoCeMnOx catalyst, prepared by coprecipitation of precursor salts, showed anincipient development of a new phase (Mn,Co)3O4 mixed spinel, due to the intimatecontact between elements.