Water-Assisted Low-Temperature Oxidation of CO at the Au–Fe<sub>2</sub>O<sub>3</sub> Interface
Chuanchuan Jin, Yan Zhou, Shaobo Han, Wenjie Shen
Abstract
The effect of water on CO oxidation over a Au/Fe2O3 catalyst, fabricated by dispersing 2.3 nm Au particles on a rod-shaped Fe2O3, was examined comprehensively. Under the dry gas condition (a CO/O2 mixture), the reaction occurred via a redox mechanism at the Au–Fe2O3 interface, where CO was adsorbed by Au and O2 was activated by Fe2O3. However, adding an appropriate amount of H2O to the feed stream has altered the reaction pathway and promoted the activity substantially. The Au particles showed a reaction rate of 0.64 mmolCO gAu–1 s–1 at 30 °C with a dry feed gas of 1.0% CO/20.0% O2/He, but the addition of 3.0% H2O to the reaction gas dramatically enhanced the reaction rate to 5.27 mmolCO gAu–1 s–1. Detailed spectroscopic characterizations have identified that CO oxidation in the presence of H2O followed a water-assisted pathway rather than the conventional redox route. H2O promoted the activation of O2 pronouncedly at the Au–Fe2O3 interface; it might react with O2 over Fe2O3, and the generated hydroxyl (−OH) species further interacted with CO, adsorbed on Au particles, forming carboxylate (−COOH) species. Finally, the carboxylate decomposed into CO2 via a proton transfer to H2O.