Abstract: A new method called adsorption column chromatography for the preparation of supported nano-gold catalysts was proposed. Au/Al₂O₃ was used as the model catalyst, and low-temperature CO oxidation was used as the model reaction. Effects of pH value of gold precursor solution, liquid-to-solid ratio of the gold precursor solution to the support, specific surface area of the support, and competition adsorbates such as water, ethanol, isopropanol, and acetone on the nano-structure of the gold catalyst were investigated. The optimal conditions are the pH value of gold precursor solution of 9, the liquid-to-solid ratio of 6:1, and acetone as the preferential adsorbate. Gold particles on the prepared Au/Al₂O₃ catalyst are well distributed and about 5 nm in diameter. The temperature for CO complete conversion is -25 ^oC. The specific surface area of Al₂O₃ has great impact on the Au/Al₂O₃ catalyst. The lower the polarity of the preferential adsorbate, the better the distribution of gold particles on the support. This method can improve the utilization ratio of gold and effectively remove toxic chlorine ions, and therefore it provides an effective way for the large-scale preparation of gold catalysts.

Key words: adsorption column chromatography, gold, carbon monoxide, oxidation, nano-structure, liquid-to-solid ratio