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

Ce0.65Fe0.33Pt0.02O2−δ and Ce0.67Fe0.33O2−δ 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−δ and Ce0.65Fe0.33Pt0.02O2−δ. Hydrogen uptake studies show strong reduction peaks at 125 °C in Ce0.65Fe0.33Pt0.02O2−δ against a hydrogen uptake peak at 420 °C in Ce0.67Fe0.33O2−δ. Fe substituted ceria, Ce0.67Fe0.33O2−δ 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 Ce0.67Fe0.33O2−δ is 2.8 μmol g−1 s−1 at 450 °C and with Pt substituted Ce0.65Fe0.33Pt0.02O2−δ is 4.05 μmol g−1 s−1 at 275 °C. Due to the synergistic interaction of the Pt ion with Ce and Fe ions in Ce0.65Fe0.33Pt0.02O2−δ, the catalyst showed much higher activity for CO oxidation and WGS reactions compared to Ce0.67Fe0.33O2−δ. A reverse WGS reaction does not occur over Ce0.65Fe0.33Pt0.02O2−δ. The catalyst also does not deactivate even when operated for a long time. Nearly 100% conversion of CO to CO2 with 100% H2 selectivity is observed in WGS reactions even up to 550 °C.

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► Ce0.65Fe0.33Pt0.02O2−δ and Ce0.67Fe0.33O2−δ catalysts are synthesized by a sonochemical method.
► Ce0.67Fe0.33O2−δ acts as a catalyst for CO oxidation and WGS reactions at moderate temperatures.
► Ce0.65Fe0.33Pt0.02O2−δ is an excellent catalyst for CO oxidation and WGS reactions at lower temperatures.
► Rate of CO conversion with the Pt free catalysts is lower, compared to Pt substituted catalysts in WGS reactions.
► No deactivation of the catalysts observed even long time start-up/shut-down operations.