Role of the FeOx support in constructing high-performance Pt/FeOx catalysts for low-temperature CO oxidation

Abstract

Based on a simple colloid deposition method, a series of Pt/FeO_x catalysts were prepared using 3–4 nm Pt colloid nanoparticles and FeO_x with different microstructures (i.e. the structure and surface properties). The FeO_x support was obtained via a thermal treatment method, which enables the tailoring of FeO_x from ferrihydrite to α-Fe₂O₃, and the amount of hydroxides on the surface of FeO_x decreases gradually with the phase change. Over optimized Pt/FeO_x, CO could be completely converted at room temperature (298 K) and a relatively high space velocity (1.2 × 10⁵ mL g⁻¹ h⁻¹). The correlation between the microstructure of the FeO_x support and the CO oxidation performance of the resultant Pt/FeO_x catalyst was investigated. Although the oxidation of Pt nanoparticles is inevitable in the Pt loading process, relatively large amounts of Pt⁰ species can be preserved on the FeO_x support possessing abundant surface hydroxides. In situ DRIFTS shows that the surface hydroxides on FeO_x could also participate in the catalytic process; they could react with CO adsorbed on Pt⁰ sites and then recover easily in the co-presence of molecular oxygen and water gas. These results show that the intrinsic properties of the FeO_x support not only affect the oxidation state of supported Pt nanoparticles in the preparation process, but also provide new active sites in the catalytic process. FeO_x supports possessing abundant surface hydroxides are suitable for preparing high-performance Pt/FeO_x catalysts for low-temperature CO oxidation.