CO catalytic combustion over CO/Al2O3: Influence of diverse textural properties of alumina supports on the related oxidation activities

摘要

A series of mesoporous aluminas were prepared by different synthesis procedures, including soft template (ST) and solvent evaporation (SE) methods, in various conditions. These mesoporous structures achieve significantly higher BET specific surface areas than the traditional one prepared by ceramic method (CE) (200-300 m~2 g~(-1) vs 58 m~2 g~(-1)). A further loading of active cobalt component was subsequently conducted over different aluminas. The structures and reducibility of these materials were fully characterized by XRD, N2 adsorption-desorption, H2-TPR, TEM and XPS, correlating to their diverse evolutions of catalytic activity for CO oxidation. The best performance achieved over the sample SE-700 (SE method, 700 °C calcination), substantially attributing to its outstanding long distance ordered mesoporous structure of the alumina support, big pore channel, high surface CoO_x content and the largest specific surface area. The catalyst ST-7.6 (ST method, pH = 7.6) showed a comparable activity, corresponding to its large pore size, the worm-like mesoporous structure and the absence of inactive CoAl2O4.