Synthesis of mesoporous ceria zirconia beads Atul S. Deshpande, Markus Niederberger * Max-Planck-Institute of Colloids and Interfaces, Colloid Chemistry, Research Campus Golm, D-14424 Potsdam, Germany Received 9 October 2006; received in revised form 29 November 2006; accepted 30 November 2006 Available online 24 January 2007 Abstract A complete range of mesoporous Ce 1x Zr x O 2 beads (x = 0–1) were synthesized by the nanocasting approach using porous polymeric beads as templates and crystalline Ce 1x Zr x O 2 nanoparticle sols as filling agent. The final beads obtained after calcination at 500 °C showed surface areas as large as 113 m 2 g 1 . According to scanning electron microscopy (SEM) and transmission electron microscopy (TEM) investigations the morphological features of the template beads are transferred to the oxide spheres. Wide-angle X-ray scattering (XRD) data and Raman studies of the samples calcined at 500 °C and 900 °C, respectively, indicate the compositional homogeneity as well as a systematic variation of the crystal properties. The ceria zirconia samples with intermediate compositions (x  0.5) were more stable towards crystal growth and loss of surface area. Ó 2006 Elsevier Inc. All rights reserved. Keywords: Ceria zirconia; Nanoparticles; Mesoporous; Nanocasting; Beads 1. Introduction CeO 2 has the ability to promote noble metal dispersion, to conduct oxide ions by switching between stable Ce 3+ and Ce 4+ states, and to provide thermal stability to catalyst supports [1]. These intrinsic properties can further be manipulated to great extents by doping or solid solution formation with a wide range of transition metal and rare- earth oxides [2] or even by changing the reaction conditions [3–5]. As a consequence, countless combinations of CeO 2 - based materials are possible. This unique feature has kept interests of researches alive despite the huge amount of scientific work on CeO 2 -based systems. Although in recent years the focus has shifted consider- ably to the investigation of nanostructured CeO 2 -based materials [6], there are only a very limited numbers of pub- lications available regarding the synthesis of ordered meso- porous materials based on CeO 2 . One of the major problems is the rapid crystallite growth during calcination, resulting in the loss of mesostructure and surface area. Sol– gel approaches based on the use of molecular precursors enabled the preparation of mesoporous thin films [7,8] and also bulk materials [9,10]. Synthesis of bulk mesopor- ous CeO 2 -based materials by nanoparticle self-assembly processes has also been demonstrated [11,12]. For catalytic applications surface area and pore connectivity are more important parameters than an ordered pore arrangement. As a matter of fact, a periodic pore structure can even have serious disadvantages such as non-optimal flow properties [13,14]. From a commercial point of view it is important to develop synthesis routes to mesoporous materials that are on the one hand easy to implement for large scale produc- tion and on the other hand provide excellent reproducibil- ity in terms of the pore architecture. In this respect templating techniques involving the use of preformed and rigid templates are particularly promising [15,16]. Porous polymer beads, generally used in chromatography, offer various features that makes them ideal candidates for this purpose. They provide good flow properties due to their interconnected pore structure, are commercially available in various pore size ranges and surface functionalities, 1387-1811/$ - see front matter Ó 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.micromeso.2006.11.036 * Corresponding author. Tel.: +49 331 5679508; fax: +49 331 5679502. E-mail address: Markus.Niederberger@mpikg.mpg.de (M. Nieder- berger). www.elsevier.com/locate/micromeso Microporous and Mesoporous Materials 101 (2007) 413–418