1993 Volume 72 Issue 11 Pages 1101-1108
Catalytic activity of an active carbon produced from active sludge waste for the reduction of NO (400ppm) in air with NH3 at a temperature range of 25 to 250°C, examining influences of humidity in air. The active carbon (R-MGAC) exhibited a remarkable stationary activity in comparison with the conventional active carbons, providing a conversion of 90% in dry air at 25°C by W/F of 5×10-3g·min/ml. Further heattreatment in N2 at 800°C reduced significantly the activity. Activation with H2SO4 (R-MGAC-S (3/400/4) increased slightly the activity in dry air. Humidity in air above 60% at 25°C decreased the activity of R-MGAC, providing a conversion of 12and 4% under 70 and 100% humidity which were about one seventh and one twentyth of that in dry air, respectively. Heattreatment at 800°C and H2SO4 treatment improved the activity in wet air, providing higher conversions of 36 and 42%, respectively under 70% humidity and 20 and 10% under 100% humidity, respectively at 25°C, although retardation by humidity was still marked. The higher reaction temperature up to 100°C de-creased the conversion in dry air but increased that in humid air. The conversion in both dry and wet air increased at higher temperatures than 100°C. Temperature programmed decomposition analysis of R-MGACs exhibited CO2 evolution at two temperature ranges of 200-450°C and 450-900°C. H2SO4 treatment increased very significantly the evolution at the first range, and the heattreatment decreased very much the evolution at the both ranges. The former treatment may enhance the activity in wet air through the more adsorption of NH3, while the latter treatment does through removal of hydrophilic groups. Remarkable activities before H2SO4 activation and significant presence of nitrogen are common to the present active carbon and the polyacrylonitrile based activated carbon fiber (PAN-ACF) in a previous paper. Participation of nitrogen group in their catalytic performance is commonly postulated, although humidity was prohibited completely the activity of the fiber.
