Supported gold catalysts for CO oxidation

Catalysts containing gold clusters dispersed on different oxide supports (CeO2, ZrO2, La2O3) were developed as alternative materials to platinum group metals (PGM), widely used in catalytic exhaust gas treatment. The catalysts were prepared by the innovative combustion synthesis method (SCS) and then characterized by XRD, BET, TEM and SEM-EDS analyses, whereas their catalytic activity towards CO oxidation was tested in a temperature programmed combustion (TPC) apparatus. Combustion synthesis allowed to achieve in a single step 5–25 nm Au clusters supported on nanostructured metal oxides powders. Significant catalytic activities were measured in the range 150–250 8C which has to be regarded as a good basis for further development. A more lengthy classical precipitation method at pH 8 was indeed also applied to the preparation best performing catalyst (2 wt.% Au-La2O3) thereby getting better results in a fresh state but practically equal after prolonged ageing (800 8C for 5 h). TPR analyses were carried out to elucidate the nature of the support-gold synergism of the 2 wt.% Au-La2O3 catalyst, which appears to be dominated by the size of the gold clusters.