Selective Oxidation of CO in Hydrogen Rich Stream over Cu-Ce/gamma-Al_2O_3 Catalysts Doped with Co:(II) CO_2 and H_2O Effect

摘要

Cu-Ce/gamma-Al_2O_3 and Cu-Ce-Co/gamma-Al_2O_3 promoted with 0.2 wt.% Co were prepared and their catalytic performance was evaluated for the selective oxidation of CO in a H_2-rich condition (1 vol.% CO+1 vol.% O_2+60 vol.% H_2 in N_2 balance).When CO_2 and H_2O were present in the reformed gas feed,both Cu-Ce/gamma-Al_2O_3 and Cu-Ce-Co/gamma-Al_2O_3 showed decrease in oxidation activity of CO at low temperature especially under 200 deg C.Compared with the Cu-Ce/gamma-Al_2O_3,however,the Cu-CeCo/gamma-Al_2O_3 showed higher resistance for the CO_2 and H_2O and also there existed a temperature window of T_(99.9) from 210 to 225 deg C corresponding to the conversion of 99.9% Co.From CO_2/H_2O-TPD,it can be concluded that the main cause for the decrease in catalytic activity may be attributed to the blockage of the active sites by competitive adsorption of water vapor and CO_2 with the reactant at low reaction temperature.