The effects of the presence of metal Fe in the CO oxidation over Ir/FeOx catalyst

• Different FeOx lead to variant Fe chemical state in Ir/FeOx after reduction.
• High activity of Ir/FeOx coming from reaction between CO at Ir and O2 at FeOx
• Metal Fe adjacent Ir significantly inhibited CO oxidation on Ir/FeOx.
• Strong binding of O2 to Fe led to high reaction barrier between CO and oxygen at Fe.
• Metal Fe blocked the contact and reaction of CO at Ir with O2 at FeOx.

The FeOx prepared by citric acid sol–gel (CA) and precipitation (PM) methods were used as supports of Ir catalysts for CO oxidation. CO could be completely oxidized at 40 °C on Ir/FeOx-CA due to the reaction between CO adsorbed at Ir and active oxygen at FeOx. The existence of metal Fe adjacent Ir significantly inhibited CO oxidation on Ir/FeOx-PM because the strong binding of oxygen to Fe could not involve in CO oxidation. Meanwhile, the presence of metal Fe isolated Ir and FeOx also blocked the reaction of CO at Ir with O2 at FeOx.

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