Cyclic molecular designed dispersion (CMDD) of Fe₂O₃ on CeO₂ promoted by Au for preferential CO oxidation in hydrogen

A novel cyclic molecular designed dispersion (CMDD) method was employed to uniformly deposit 0.0–6.5 wt% Fe on CeO₂. The gold catalysts (0.0–3.8 wt%) supported on Fe₂O₃-CeO₂ were tested for CO preferential oxidation (PROX). As the CMDD method involved grafting of Fe (acac)₃ onto the surface –OH groups, 2.7 surface –OH/nm² was determined for the CeO₂ by using the Grignard reagent. The performance of CMDD catalysts was compared with the corresponding catalysts prepared by impregnation. The catalysts were characterized by XPS, XRD, TPR, HRTEM-EDX, BET and ICP. The results suggested that Au/Fe₂O₃-CeO₂ was significantly more active and selective than Au/CeO₂. The CMDD-prepared catalysts with 1.4–2.5 wt% iron showed the highest activity and selectivity, especially at temperatures as low as 323 K. The formation of Ce-Fe solid solution for CMDD catalysts promoted the dispersion of both iron and gold. Highly dispersed gold nanoparticles mainly as small as 2.2 nm were observed in HRTEM.