Gold particles, catalyst supports dioxide

Titanium dioxide supported gold catalysts exhibit excellent activity for CO oxidation even at temperatures as low as 90 K [1]. The key is the high dispersion of the nanostructured gold particles over the semiconducting Ti02 support. The potential applications of ambient temperature CO oxidation catalysts include air purifier, gas sensor and fuel cell [2]. This work investigates the effects of ozone pretreatment on the performance of Au/Ti02 for CO oxidation. 

A supercritical anti-solvent precipitation technique has been used to prepare a novel Titania catalyst support. The Titania precursor was prepared by precipitating TiO (acac)2 from a solution of methanol using supercritical carbon dioxide at 110 bar and 40°C. The surface area of the supercritical precursor was 160 m g and this decreased to 35 mV after calcination, although there was no significant reduction of particle size. The new titania support was used to prepare a supported gold catalyst and this was tested for ambient temperature carbon monoxide oxidation. The supercritical catalyst demonstrated notably high activity when compared with catalysts prepared by other nonsupercriticd methods. 

The particle size of gold was less than 4 nm. Product selectivity is greatly affected by the support oxides. Au/Fc203 and Au/Ti02 were shown to be more active for hydrocarbon formation and for both forward and reverse water-gas shift reactions. Over all the catalysts tested by Haruta s group, carbon dioxide produced methanol at lower temperatures and produced methane more selectively than carbon monoxide [469]. 

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