Investigations on gold nanoparticles in mesoporous and microporous materials

The gold nanoparticles in different high surface area mesoporous and microporous materials were prepared using sol-gel and hydrothermal crystallization methods. For investigating the characteristics behaviour of nano gold particles in the mesoporous and microporous materials, Au-Al-MCM-41. Au-ZSM-5 and Au-LSX were prepared with different framework composition and concentrations of gold nanoparticles. The Au-Al-MCM-41, Au-ZSM-5 and Au-LSX samples were characterized using the BET, FTIR, ICP-MS, XAS, XPS, TEM and XRD. The XPS measurements indicate that the presence of gold species in different oxidation state and concentration of gold metal species varies over the surfaces of as-synthesized and calcined gold containing mesoporous and microporous materials. In these materials, the size of gold nanoparticles varied in the range of similar to 2-6 nm. The dispersion and size of gold nanoparticles are different in the materials with MCM-41, ZSM-5 and LSX structures. The interaction of NO/CO with the nano gold materials under different reaction temperatures and NO/CO pressures have been studied using in-FTIR technique. In situ high temperature XRD measurements were conducted over the materials in order to investigate the fate of gold nanoparticles and phase transformations at high temperatures (303-1873 K) within the mesoporous and microporous matrices. (c) 2005 Elsevier B.V. All rights reserved.