Cobalt ferrite nanoparticles for the preferential oxidation of CO

• Cobalt ferrite prepared by glucose-assisted hydrothermal method.
• Cobalt ferrite nanostructure.
• High catalytic activity on deep CO removal in hydrogen-rich stream.
• Good stability in CO-PROX reaction during 30 h.
• Promising potential in further application in PEMFCs.

In the present study cobalt ferrite (CoFe2O4) nanoparticles have been successfully prepared through the glucose-assisted hydrothermal method. We verified that the use of glucose is highly advantageous for the synthesis in order to prevent particle agglomerates as well as to obtain single-phase CoFe2O4 nanoparticles. The H2-TPR results showed that the CoFe2O4 indicates the reduction of CoO to Co° and of Fe2O3 to Fe3O4 followed by the reduction of Fe3O4 to metallic iron Fe°. XPS observations evidenced the presence of Fe3+ and Co2+ and practically exclude the existence of Fe2+ and Co3+ species at the surface. In situ DRIFTS-MS showed formate species at 100 °C which increased with increasing temperature due to the reaction between CO gas and hydroxyl groups of cobalt ferrite. The as-prepared material exhibited high CO conversion and good stability on stream at 250 °C during 30 h. In addition, it has been observed that the cobalt ferrite catalyst is inhibited by the presence of H2O and CO2, although a totally reversible process, but have no influence on the chemical structure of the surface active sites.

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