Catalytic performance of gold catalysts in the total oxidation of VOCs

Catalysts for the oxidation of volatile organic compounds (VOCs) were prepared by supporting 1% gold on cerium and zirconium oxides (CeO2, Ce0.5Zr0.5O2, ZrO2) using a simple impregnation method followed by reduction of gold in the presence or absence of ammonia (N). The catalysts were tested in model reactions, namely the total oxidation of benzene, hexane and chlorobenzene, using a micro flow reactor at atmospheric pressure in the temperature range 100-500°C and their activity was compared to that of Au/TiO2 and Au/Fe2O3 reference catalysts supplied by the World Gold Council (WGC). Benefits on the light-off temperatures were observed by adding gold to cerium-containing oxides: 100% conversion of hexane was obtained with Au/Ce0.5Zr 0.5O2 at the lowest temperature (300°C). Full conversion of benzene was reached at only 250°C with Au/CeO2 (N), at 290°C with Au/Fe2O3 (WGC) and at 300°C with Au/Ce0.5Zr0.5O2. In the case of chlorobenzene oxidation, the addition of gold was of even greater relevance because of a drop in the light-off temperature of over 100°C for Au/Ce0.5Zr 0.5O2 and Au/CeO2, with respect to the gold-free oxide supports; but in this case rapid deactivation took place.