Iron-modified ceria and Au/ceria catalysts for Total and Preferential Oxidation of CO (TOX and PROX)

Iron-modified ceria supports containing different molar percentages of Fe (0%, 10%, 25%, and 50%) were synthesized by thermal decomposition of the metal propionates. The formation of a Ce–Fe oxide solid solution is evidenced through XRF, XRD, BET and Raman spectroscopy. For iron contents above 25% the formation of α-Fe2O3 was detected, pointing out the formation of the isolated oxides. The catalytic activity of the Fe-modified catalysts in the Total Oxidation of CO reaction (TOX) is higher than for the bare CeO2 material. The synergy between Ce and Fe shows a maximum for 10% Fe content (CeFe10), catalyst that shows the highest CO conversion per atom of Fe incorporated. Gold catalyst was also prepared on CeFe10 and its catalytic activity compared with Au/CeO2 catalyst. The addition of iron to the gold catalyst resulted in an enhancement of the catalytic activity for CO oxidation especially at low temperature. This Au/CeFe10 catalyst was also active and selective with excellent stability in the Preferential Oxidation of CO (PROX) showing a higher CO conversion than the Au/CeO2 catalyst at temperatures below 150 °C being hardly affected by the presence of CO2 and H2O in the gas stream.