Effect of calcination temperature on the catalytic activity of Au colloids mechanically mixed with TiO₂ powder for CO oxidation

Abstract

In order to elucidate the role of the contact structure between gold and metal oxide support in low-temperature CO oxidation, a mechanical mixture of colloidal gold with TiO₂ powder was prepared and calcined at different temperatures. The sample calcined at 473 K, which is composed of spherical gold particles with a mean diameter of 5.1 nm and TiO₂ powder, is poorly active for CO oxidation at temperatures up to 473 K. The catalytic activity appreciably increases with an increase in calcination temperature up to 873 K even though gold particles grow to larger ones, reaching a level with almost the same turnover frequency as that of Au/TiO₂ prepared by a deposition–precipitation method.