A Rapid and Efficient Method to Deposit Gold Particles onto Catalyst Supports and Its Application for CO Oxidation at Low Temperatures

Authors


  • This research was supported by the Agency for Science, Technology, and Research in Singapore (A-STAR, ICES03-414002). Z.Z. thanks Gary Ng, Suriya Subramanian, Vivien Ng, Zhan Wang, and Weiqiang Lim for technical assistance, and Dr. Keith Carpenter and Dr. P. K. Wong for their kind support to this project. Supporting Information is available online from Wiley InterScience or from the authors.

Abstract

A rapid, simple, and efficient method for the preparation of highly dispersed supported Au catalysts has been developed. In the preparation, NaBH4 is used to reduce the Au precursor, lysine is employed to cap the formed Au colloids, and a short sonication time is applied to facilitate dispersion and deposition of the Au colloids onto the catalyst support, which has been mixed with the precursor beforehand. The end-point pH value of the solution and the isoelectric points (IEPs) of the catalyst supports have an influence on the size of the Au particles and their deposition. The optimum value for the end-point pH is 7.5–10.0, and the IEP should be 5–10. The amino acid capping agent is easily removed at the catalyst activation stage at 200 °C, and the Au particles are thermally stable against sintering, even at 500 °C for 3 h. It is also proven that the method is applicable to the preparation of supported Pt catalysts. The catalytic activity of the prepared Au catalysts for CO oxidation in the absence/presence of H2 is comparable to that of a Au catalyst prepared by the co-precipitation (CP) method, and to that of the standard catalyst from the World Gold Council (WGC). X-ray photoelectron spectroscopy (XPS) results show that only metallic Au exists in the catalysts before and after activation, and also after the catalysis reaction.

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