Preparation, thermal stability, and CO oxidation activity of highly loaded Au/titania-coated silica aerogel catalysts

Abstract

Abstract We have prepared Au/titania-coated silica aerogel catalysts having Au loadings ranging from 0.14 to 20 wt.% using the liquid phase adsorption of preformed Au nanoparticles (NPs) onto the support. Using transmission electron microscopy, we confirmed that AuNPs as small as 2 nm were well dispersed in the catalyst samples, preserving their original diameters after heat treatment at 673 K. As a result, in contrast to the behavior of catalysts prepared using the conventional deposition–precipitation method, the CO oxidation activity per catalyst increased monotonously with increasing Au loading. These results suggest that this preparation procedure and support allow the AuNPs to preserve their intrinsic oxidation activities over a wide loading range. We also found that the AuNPs on this support were resistant to thermal sintering: the diameter of the particles remained well below 5 nm even after calcination at 973 K for 2 h.