Au/CeO 2 Catalysts for Catalytic Abatement of CO, CH 3 OH and (CH 3 ) 2 O: Effect of Preparation Method Tatyana Tabakova Institute of Catalysis Bulgarian Academy of Sciences 1113 Sofia, Bulgaria Maela Manzoli, Flora Boccuzzi Department of Chemistry IFM and NIS Centre of Excellence University of Torino 10125 Torino, Italy Dimitar Dimitrov, Krassimir Ivanov Department of Chemistry Agricultural University 4000 Plovdiv, Bulgaria Boyan Boyanov Faculty of Chemistry Plovdiv University 4000 Plovdiv, Bulgaria Abstract—Two different synthesis routes, in particular deposition-precipitation (DP) and modified deposition- precipitation (MDP) have been used for preparation of gold/ceria catalysts. The catalysts have exhibited significant differences in CO, CH 3 OH and (CH 3 ) 2 O oxidation. The most pronounced effect of different preparation methods was registered in the CO oxidation reaction. DP-prepared catalyst showed high ability to oxidize CO at room temperature. Microscopic measurements have evidenced formation of very small gold particles (d below 1 nm) on the surface of DP- prepared catalyst. In contrast, only large gold particles with average size about 15 nm were observed in MDP-prepared sample. A detailed characterization by FTIR spectroscopy after CO adsorption at 90 K and TPR measurements has been carried out with aim to unravel the impact of preparation method on the structural and catalytic properties of the catalysts. The catalytic behavior was explained with the large differences in the gold dispersion and in the number of active gold sites in intimate contact with ceria surface defects. Keywords-gold/ceria catalyst, catalytic abatement of CO, CH 3 OH and (CH 3 ) 2 O, HRTEM, FTIR I. INTRODUCTION The increasing social and political concern in environment has stimulated interest to development of catalytic processes that can reduce harmful emissions from various domestic or industrial activities. The catalytic oxidation has been considered as very efficient way to destroy volatile organic compounds (VOCs). It is an interesting solution for VOCs elimination in comparison with thermal combustion due to the lower temperature required and to its higher selectivity [1]. During the past two decades gold catalysts have demonstrated high effectiveness for many reactions of environmental significance. Gold-based catalysts have attracted great interest after pioneering work of Haruta et al. for extremely high CO oxidation activity at very low temperature (200 K) of gold nanoparticles supported on metal oxides [2]. The preparation of gold catalysts is of particular importance because it influences the size of gold particles and their interaction with the support. The selection of support also has impact on the catalytic activity. An appropriate support should prevent the coalescence and agglomeration of the gold nanoparticles on one side, but should be able to participate actively in the reaction mechanism by redox cycle of the support metal ions, on the other. Ceria is a very attractive support material mainly for its role in oxygen storage, releasing and taking up oxygen depending on redox conditions, which results in rapid formation and elimination of oxygen vacancy defects [3]. The aim of the present study was to examine the catalytic activity of Au/CeO 2 for abatement of air pollutants – CH 3 OH, (CH 3 ) 2 O and CO in waste gases. High resolution transmission electron microscopy (HRTEM), X-ray diffraction, Fourier transformed infrared spectroscopy (FTIR) of CO at 90 and temperature-programmed reduction (TPR) measurements were carried out to study the role of different synthesis methods on the structural peculiarities of the catalysts and to clarify the relationship between structure and catalytic performance. II. EXPERIMENTAL A. Catalyst preparation Au/ceria catalysts were prepared via two different techniques, namely the deposition-precipitation (DP) and the modified version of the deposition-precipitation (MDP) method. A DP method took place by deposition of gold hydroxide at constant pH 7.0 and at 333 K on ceria suspended in water by ultrasound. Ceria, used as a carrier, was laboratory-made by coprecipitation of Ce(NO 3 ) 3 .6H 2 O and K 2 CO 3 at constant pH (9.0) and at 333 K, drying in vacuum at 353 K and calcination in air at 673 K for two hours. In the case of MDP, a desired amount of ACKNOWLEDGMENT: This work was supported by the National Science Fund of Bulgaria through Project DDVU-02/7. 2012 International Conference on Biomedical Engineering and Biotechnology 978-0-7695-4706-0/12 $26.00 © 2012 IEEE DOI 10.1109/iCBEB.2012.471 78