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Au has been loaded (1% wt.) on different commercial oxide supports (CuO, La2O3, Y2O3, NiO) by three different methods: double impregnation (DIM), liquid-phase reductive deposition (LPRD), and ultrasonication (US). Samples were characterised by N2 adsorption at −196 ℃, high-resolution transmission electron microscopy, selected area electron diffraction, energy dispersive X-ray spectrometry, high-angle annular dark-field imaging (Z-contrast), X-ray diffraction, and temperature programmed reduction. CO oxidation was used as a test reaction to compare the catalytic activities. The best results were obtained with Au loaded by DIM on the NiO support, with an activity of 7.2 × 10−4 molCO·gAu−1·s−1 at room temperature. This is most likely related to the Au nanoparticle size being the smallest in this catalyst (average 4.8 nm), since it is well known that gold particle size determines the catalytic activity. Other samples, having larger Au particle sizes (in the 2–12 nm range, with average sizes ranging from 4.8 to 6.8 nm), showed lower activities. Nevertheless, all samples prepared by DIM had activities (from 1.1 × 10−4 to 7.2 × 10−4 molCO·gAu−1·s−1, at room temperature) above those reported in the literature for gold on similar oxide supports. Therefore, this method gives better results than the most usual methods of deposition–precipitation or co-precipitation.

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Publication history

Received: 02 September 2010
Revised: 07 October 2010
Accepted: 28 October 2010
Published: 01 February 2011
Issue date: February 2011

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© The Author(s) 2010

Acknowledgements

Acknowledgements

The authors thank Fundação para a Ciência e a Tecnologia (FCT), Portugal, for financial support (CIENCIA 2007 program for Sónia Carabineiro (SAC)), and project PTDC/EQU-ERQ/101456/2008, financed by Fundação para a Ciência e Tecnologia (FCT) and FEDER in the context of Programme COMPETE. Funds from Mexican Consejo Nacional de Ciencia y Tecnologia (CONACYT) grant No. 79062 and Programa de Apoyo a Proyectos de Investigación e Innovación Tecnológica (PAPIT-UNAM) grant No. IN 100908 are also acknowledged. The authors thank Laboratorio de Investigaciones en Nanociencias y Nanotecnologia (LINAN) laboratory from IPICyT for providing microscopy and simulation services for this work.

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