Au/xCeO(2)/Al2O3 catalysts for VOC elimination: oxidation of 2-propanol

International audience2- Propanol oxidation (1 mol% in air) was investigated over 1% Au/CeO2, 1% Au/Al2O3 and 1% Au/xCeO(2)/Al2O3 (x = 1.5, 3, 5 and 10 wt%) catalysts and the corresponding pure supports. The effects of the catalyst activation procedure (calcination or reduction), cerium oxide morphology and loading, the presence/absence of O-2 in the feed, and stability of activity were studied. The nature of the support strongly influences the 2- propanol oxidation pathway, and one can distinguish three reaction temperature ranges: low (50- 150 degrees C), intermediate (175- 250 degrees C) and high (> 300 degrees C). In the low temperature range, only acetone is formed whatever the nature of the support. On Au/Al2O3 and Au/xCeO(2)/Al2O3 catalysts propene becomes the main reaction product by increasing the temperature, followed by CO2 formation at higher temperature. The acidic character of Al2O3 and CeO2/Al2O3 promotes the propene formation whereas the basic one of CeO2 favors the formation of acetone, and the gold catalysts also present an acidic- basic behavior, which depends largely on the reaction temperature. Replacing air with He during the catalytic run over Au/Al2O3 and Au/CeO2 provides evidence of how O-2 is activated by Au, revealing, as expected, that dehydrogenation to form acetone and total oxidation to CO2 require both O-2 and Au as the catalyst, whereas dehydration to form propene does not require O-2. For both calcined and reduced catalysts, the catalytic activity towards total oxidation varies in the order: Au/CeO2 > Au/xCeO(2)/Al2O3 > Au/Al2O3