Journal of Molecular Catalysis A: Chemical 236 (2005) 77–86 Investigations on gold nanoparticles in mesoporous and microporous materials Deepak B Akolekar ∗ , Suresh K Bhargava ∗∗ Catalysis and Advanced Materials Research Group School of Applied Sciences, Science, Engineering and Technology Portfolio, RMIT University, City Campus, Melbourne, Victoria 3001, Australia Received 14 February 2005; received in revised form 30 March 2005; accepted 31 March 2005 Available online 23 May 2005 Abstract 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 ∼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. © 2005 Elsevier B.V. All rights reserved. Keywords: Gold nanoparticles; Mesoporous materials; MCM-41; Microporous materials; ZSM-5; LSX; Low silica faujasite; Surface properties; Au; XRD; Synthesis. In situ HTXRD 1. Introduction Currently nano-materials attract considerable attention due to a variety of novel features. New physical, chemical, and thermodynamic properties are expected to occur in such systems, arising from the large fraction of low coordinated atoms at the surface and the confinement of electrons to a rather small volume, respectively [1]. From a technical point of view, however, the development of future applications will need to adhere/support the nanoscaled materials on suitable substrates in two- or three-dimensional arrangements in ∗ Corresponding author. Tel.: +61 3 99252121; fax: +61 2 96391321. ∗∗ Corresponding author. E-mail addresses: E04781@ems.rmit.edu.au (D.B. Akolekar), suresh.bhargava@rmit.edu.au (S.K. Bhargava). order to take advantage of their fascinating properties under different conditions. Gold exhibits a unique catalytic nature and action when it is deposited as nanoparticles on a variety of metal oxides. Currently, nano gold materials are employed in low temperature CO oxidation in hydrogen stream, CO gas sensors, selective oxidation of alkanes, olefins, and alcoholic compounds, oxidation of nitrogen-containing compounds, selective hydrogenation of 1,3-butadiene, methanol synthesis, reduction of NO x , etc. [2–9]. The catalytic and adsorption properties are influenced by the dispersion, structure and interaction of gold nanoparticles with the support as well as by the support type [8,10–13]. The new generation microporous and mesoporous mate- rials are increasingly being used in various commercial cat- alysts because of their high surface area, unique pore sizes, 1381-1169/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.molcata.2005.03.048