Design of a highly active Pt/Al2O3 catalyst for low-temperature CO oxidation

Abstract

A series of Al₂O₃ supported platinum catalysts (Pt/Al₂O₃), were prepared by a colloid deposition route. The Pt chemical state and nanostructure over the Pt/Al₂O₃ catalysts were characterized after calcination treatment using X-ray photoelectron spectroscopy and transmission electron microscopy. The Pt chemical state and nanostructure depended on the treatment temperature: a metallic Pt surface was formed on the Pt/Al₂O₃ catalysts calcined at low temperature, whereas oxidized Pt existed after the relatively high temperature treatment. The Al₂O₃ support acted as an anchor and inhibited the sintering of Pt particles on the catalyst surface through intimate interaction between Al₂O₃ and Pt. The Pt/Al₂O₃ catalyst pre-treated at 200 °C (i.e., Pt/Al₂O₃-200) exhibited relatively high activity for CO oxidation. According to the results of catalyst characterization, Pt/Al₂O₃-200 could efficiently govern O₂ adsorption by trapping O₂ molecules on Pt sites and producing active oxygen species. That is, the surface metallic Pt could facilitate the adsorption and activation of O₂ molecules even with the CO pre-adsorption on the surface of Pt particles.