Ce0.67Fe0.33O2-δ and Ce0.65Fe0.33Pt0.02O2-δ: New water gas shift (WGS) catalysts

Ce0.65Fe0.33Pt0.02O2-delta and Ce0.67Fe0.33O2-delta have been synthesized by a new low temperature sonochemical method using diethylenetriamine as a complexing agent. Due to the substitution of Fe and Pt ions in CeO2, lattice oxygen is activated in Ce0.67Fe0.33O2-delta and Ce0.65Fe0.33Pt0.02O2-delta. Hydrogen uptake studies show strong reduction peaks at 125 C in Ce0.65Fe0.33Pt0.02O2-delta against a hydrogen uptake peak at 420 degrees C in Ce0.67Fe0.33O2-delta. Fe substituted ceria, Ce0.67Fe0.33O2-delta itself acts as a catalyst for CO oxidation and water gas shift (WGS) reactions at moderate temperatures. The rate of CO conversion in WGS with Pt free Ce0.65Fe0.33O2-delta is 2.8 mu mol g(-1) s(-1) at 450 C and with Pt substituted Ce0.65Fe0.33Pt0.02O2-delta is 4.05 mu mol g(-1) s(-1) at 275 degrees C. Due to the synergistic interaction of the Pt ion with Ce and Fe ions in Ce0.65Fe0.33Pt0.02O2-delta, the catalyst showed much higher activity for CO oxidation and WGS reactions compared to Ce0.67Fe0.33O2-delta. A reverse WGS reaction does not occur over Ce0.65Fe0.33Pt0.02O2-delta. The catalyst also does not deactivate even when operated for a long time. Nearly 100% conversion of CO to CO2 with 100% H-2 selectivity is observed in WGS reactions even up to 550 degrees C. (C) 2011 Elsevier B.V. All rights reserved.