(359a) Spray Flame Pyrolysis Verses Deposition Precipitation as Synthesis Routes for Au/TiO2 Catalyst for CO Oxidation

Supported gold catalysts were synthesized on titanium dioxide (TiO₂) using spray flame pyrolysis (SFP) and deposition precipitation (DP) methods. The activity of catalyst prepared by DP method is significantly higher then those prepared by SFP for the same gold loading. The gold particle size and size distribution is significantly smaller for the DP prepared catalysts compared to the SFP catalyst. The shape of deposited gold particles from DP method seem to be raftlike two dimensional (2D: height below two atomic-layers) surface layers of gold on titania. In contrast the gold particles for flame made Au/ TiO₂ are mostly spherical three dimensional (3D) nano-crystals embedded on the TiO₂ surface. In addition to the gold particles the TiO₂ support produced by the spray flame pyrolysis method has different crystal structure and nano structure compared to the Degussa, P25 TiO₂. We relate the differences in the catalytic activity to the shape and size characteristics of the catalysts obtained by the two methods, and investigate the way forward to obtaining higher activity Au/TiO₂ catalyst using SFP.