Preparation and Characterization of Nanostructured Au/TiO2 Catalyst with High Thermal Stability

Abstract

Abstract Mesoporous TiO 2 was synthesized using triblock copolymer EO 20 PO 70 EO 20 (P123) as the organic template, and the Au/TiO 2 catalyst was prepared by the deposition-precipitation method. For comparison, industrial TiO 2 and a TiO 2 sample synthesized by the sol-gel method were also used as supports to prepare the Au/TiO 2 catalysts. N 2 adsorption-desorption, X-ray diffraction, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy were employed to characterize the structure and the morphology of the catalysts. The results show that the TiO 2 support synthesized using P123 as the organic template possesses uniform mesoporous structure with a narrow pore size distribution centered at ∼6.1 nm. After Au is supported on TiO 2 , the mesoporous structure of TiO 2 is well maintained and the pore size is decreased to ∼5.4 nm. The gold in the mesoporous TiO 2 -supported catalyst calcined at 400°C exists as Au 0 . The dispersion and the crystal size of Au on the three types of TiO 2 show considerable difference. On the TiO 2 prepared using P123, the crystal size of Au is 1-5 nm after calcination at 400°C, while on the other two supports, the crystal size of Au reaches ∼10 nm. The former Au/TiO 2 catalyst exhibits very high activity and thermal stability for the ambient CO oxidation reaction even after calcination at 420°C, and the CO conversion over this catalyst is higher than 90%. The other two Au catalysts, which were prepared using industrial TiO 2 and the TiO 2 support synthesized by the sol-gel method, exhibit poor thermal stability and catalytic activity.