Supported gold cluster catalysts prepared by solid grinding using a non-volatile organogold complex for low-temperature CO oxidation and the effect of potassium on gold particle size

Abstract We have found that physical mixing (solid grinding, SG) of dimethylgold(III) acetylacetonate (Me 2 Au(acac)) adsorbed on SiO 2 with potassium t -butoxide (KO t Bu) significantly improved the catalytic activity for CO oxidation at low temperature, and T 1/2 (the temperature at 50% CO conversion) became extremely low such as −43 °C. We have also developed an alternative Au complex for SG, and 2-( p -tolyl)pyridinebis(trifluoroacetate)gold(III) (AuTFA) could be adsorbed on metal oxide (MO x ) supports by physical mixing of AuTFA with MO x in air at room temperature for 20 min, and small Au nanoparticles (NPs) were deposited after calcination. The sizes of Au NPs were almost the same as those prepared using Me 2 Au(acac) and smaller than those prepared by DP for Al 2 O 3 and TiO 2 supports. In addition, grinding AuTFA adsorbed on SiO 2 with KO t Bu was also effective for reducing the size of Au particles and gave Au clusters with a mean diameter of 2.2 nm. Moreover, Au/Al 2 O 3 and Au/K-SiO 2 exhibited high catalytic activity for CO oxidation under simulated real exhaust gas conditions (low CO concentration and high humidity up to 100% relative humidity) at ambient temperature.