Abstract
Hydrothermal and co-precipitation methods were studied as two different methods for the synthesis of CeO2nanocatalysts. Co/CeO2 catalysts supported by 2, 4, 6, or 8wt% Co were further synthesized through impregnation and the performance of the catalytic oxidation of CO has been investigated. The highest specific surface area and the best catalytic performance was obtained by the catalyst 4wt% Co/CeO2 with the CeO2 support synthesized by the hydrothermal method (4% Co/CeO2-h), which yielded 100% CO conversion at 130 °C. The formation of CeO2 nanoparticles was confirmed by TEM analysis. XRD and SEM-EDX mapping analyses indicated that CoOx is highly dispersed on the 4% Co/CeO2-h catalyst surface. H2-TPR and O2-TPD results showed that 4% Co/CeO2-h possesses the best redox properties and the highest amount of chemically adsorbed oxygen on its surface among all tested catalysts. Raman and XPS spectra showed strong interactions between highly dispersed Co2+ active sites and exposed Ce3+ on the surface of the CeO2 support, resulting in the formation of the strong redox cycle Ce4+ + Co2+↔ Ce3+ + Co3+.This may explain that 4% Co/CeO2-h exhibited the best catalytic activity among all tested catalysts.
Highlights
In the last decades, the application of metal oxide nanoparticles in the field of catalysis has experienced an unprecedented growth because of their significant contributions to environmental protection and energy utilization [1,2,3]
The mixed oxides revealed superior performances compared with pure CeO2 catalyst, and the temperature of 100% conversion remarkably decreased after Co loading
The 4wt% Co/CeO2 catalyst containing CeO2 support synthesized by the hydrothermal method yielded nearly 100% carbon monoxide (CO) conversion at 130 ◦ C
Summary
The application of metal oxide nanoparticles in the field of catalysis has experienced an unprecedented growth because of their significant contributions to environmental protection and energy utilization [1,2,3]. Growth law and influencing factors of different CeO2 crystal faces have been reported, showing that shape (as well as size) and surface/face reconstruction of CeO2 can be controlled at the nanoscale Based on these parameters, catalyst activity and stability can be effectively governed in catalytic reactions. Chen et al [18] loaded Pd on the specific crystal plane of CeO2 nanoparticles and studied the electronic metal-support interactions (EMSI) in CO oxidation. They showed that interactions on well-defined interfaces improved the catalytic performance. The results indicated that CeO2 nanoparticles prepared by the hydrothermal method with a loading of 4wt% Co possess the best CO oxidation performance
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