Preparation and characterization of nano-structured Au/TiO2 catalyst with high thermal stability

Mesoporous TiO2 was synthesized using triblock copolymer EO20PO70EO20(P123) as the organic template, and the Au/TiO2 catalyst was prepared by the deposition-precipitation method. For comparison, industrial TiO2 and a TiO2 sample synthesized by the sol-gel method were also used as supports to prepare the Au/TiO2 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 TiO2 support synthesized using P123 as the organic template possesses uniform mesoporous structure with a narrow pore size distribution centered at similar to 6.1 nm. After supporting Au, the mesoporous structure of TiO2 is well maintained only with the pore size decreasing to similar to 5.4 nm. The gold in the mesoporous TiO2-supported catalyst calcined at 400 degrees C exists as Au-0. The dispersion and the crystal size of An on the three kinds of TiO2 show much difference. On the TiO2 prepared using P123, the crystal size of Au is 1 -5 nm after calcination at 400 degrees C, while on the other two supports, the Au crystal size reaches similar to 10 nm. In the ambient CO oxidation reaction, the former Au/TiO2 catalyst exhibits very high activity and thermal stability even after calcination at 420 degrees C, and the CO conversion over this catalyst is more than 90%. The other two Au catalysts supported on the industrial TiO2 and the TiO2 synthesized by the sol-gel method are almost completely deactivated after calcination at 320 and 370 degrees C, respectively.