Preferential CO oxidation in H2-rich gas mixtures over Au/doped ceria catalysts

Nanosized gold catalysts supported on doped ceria were prepared by deposition–precipitation method. A deep characterization study by HRTEM/EDS, XRD, FT-Raman, TPR and FTIR was undergone in order to investigate the effect of ceria modification by various cations (Sm3+, La3+ and Zn2+) on structural and redox properties of gold catalysts. Doping of ceria affected in different way catalytic activity towards purification of H2 via preferential CO oxidation. The following activity order was observed: Au/Zn–CeO2 > Au/Sm–CeO2 > Au/CeO2 > Au/La–CeO2. The differences in CO oxidation rates were ascribed to different concentration of metallic gold particles on the surface of Au catalysts (as confirmed by the intensity of the band at 2103 cm−1 in the FTIR spectra collected during CO–O2 interaction). Gold catalysts on modified ceria showed improved tolerance towards the presence of CO2 and H2O in the PROX feed. The spectroscopic experiments evidence enhanced reactivity when PROX is performed in the presence of H2O already at 90 K.