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

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 degrees 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 O-2 adsorption by trapping O-2 molecules on Pt sites and producing active oxygen species. That is, the surface metallic Pt could facilitate the adsorption and activation of O-2 molecules even with the CO pre-adsorption on the surface of Pt particles.