Cobalt ferrite nanoparticles for the preferential oxidation of CO

Abstract In the present study cobalt ferrite (CoFe 2 O 4 ) 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 CoFe 2 O 4 nanoparticles. The H 2 -TPR results showed that the CoFe 2 O 4 indicates the reduction of CoO to Co° and of Fe 2 O 3 to Fe 3 O 4 followed by the reduction of Fe 3 O 4 to metallic iron Fe°. XPS observations evidenced the presence of Fe 3+ and Co 2+ and practically exclude the existence of Fe 2+ and Co 3+ 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 H 2 O and CO 2 , although a totally reversible process, but have no influence on the chemical structure of the surface active sites.