Monodispersed gold nanoparticles supported on γ-Al2O3 for enhancement of low-temperature catalytic oxidation of CO

Abstract

Monodispersed nano-Au/γ-Al2O3 catalysts for low-temperature oxidation of CO have been prepared via a modified colloidal deposition route, which involves the deposition of dodecanethiolate self-assembled monolayer (SAM)-protected gold nanoparticles (C12 nano-Au) in hexane on γ-Al2O3 at room temperature. The diameter of the gold nanoparticles deposited on the support is 2.5±0.8nm after thermal treatment, and their valence states comprise both the metallic and oxidized states. It is found that the thermal treatment temperature affects significantly the catalytic activity of the catalysts in the processing steps. The catalyst treated at 190°C exhibits considerably higher activity as compared to catalysts treated at 165 and 250°C. A 2.0-wt.% nano-Au/γ-Al2O3 catalyst treated at 190°C for 15h maintains the catalytic activity at nearly 100% CO oxidation for at least 800h at 15°C, at least 600h at 0°C, and even longer than 450h at −5°C. Evidently, the catalysts obtained using this preparation route show high catalytic activity, particularly at low temperatures, and a good long-term stability.