Abstract: In order to study the de NO_x performance of biomass materials, activated carbons derived from lignocellulosic and herbaceous biomasses were selected as the reducing agents, and alkali and transition metals were used as the catalytic active phases to prepare a series of activated carbon-supported metals for the catalytic reduction of NO_x to N₂ in excess O₂. The effects of the type of biomass, carbonization temperature and catalyst composition on NO_x reduction efficiency were analyzed. The results showed that:(1) Two temperature regimes are present for the NO_x-carbon reaction:at temperatures below 250℃, the NO_x adsorption process on the carbon surface was predominant, whereas true NO_x reduction by carbon occurred at temperatures above 250℃, producing N₂, CO₂ and CO. The influence of the carbonization temperature on carbon reactivity depended on the effect of the carbonization temperature on the oxygen-containing functional groups, the carbon surface area and the reduction of the metal species on carbon. (2) All studied metals catalyzed both NO_x and O₂ reduction by carbon, and potassium could strongly enhance the C-NO_x reaction without substantial carbon consumption by O₂. The sample SAC-K showed the highest selectivity factor of 0.56 among the samples, and the NO_x reduction by SAC-K was 1293 μmol/g C. (3) Moreover, the potassium supported by sawdust-derived activated carbon exhibited higher selectivity and capacity towards NO_x reduction than its previously reported coal-derived counterparts. These properties were ascribed to the high dispersion of the active potassium species on the carbon surface, as observed through comparison of powder X-ray diffraction results for the carbons made from biomass and coal-based precursors. The above results suggested that in comparison with coal-derived carbon materials the biomass-derived carbon materials showed better selective reduction of NO_x.In order to study the de NO_x performance of biomass materials, activated carbons derived from lignocellulosic and herbaceous biomasses were selected as the reducing agents, and alkali and transition metals were used as the catalytic active phases to prepare a series of activated carbon-supported metals for the catalytic reduction of NO_x to N₂ in excess O₂. The effects of the type of biomass, carbonization temperature and catalyst composition on NO_x reduction efficiency were analyzed. The results showed that:(1) Two temperature regimes are present for the NO_x-carbon reaction:at temperatures below 250℃, the NO_x adsorption process on the carbon surface was predominant, whereas true NO_x reduction by carbon occurred at temperatures above 250℃, producing N₂, CO₂ and CO. The influence of the carbonization temperature on carbon reactivity depended on the effect of the carbonization temperature on the oxygen-containing functional groups, the carbon surface area and the reduction of the metal species on carbon. (2) All studied metals catalyzed both NO_x and O₂ reduction by carbon, and potassium could strongly enhance the C-NO_x reaction without substantial carbon consumption by O₂. The sample SAC-K showed the highest selectivity factor of 0.56 among the samples, and the NO_x reduction by SAC-K was 1293 μmol/g C. (3) Moreover, the potassium supported by sawdust-derived activated carbon exhibited higher selectivity and capacity towards NO_x reduction than its previously reported coal-derived counterparts. These properties were ascribed to the high dispersion of the active potassium species on the carbon surface, as observed through comparison of powder X-ray diffraction results for the carbons made from biomass and coal-based precursors. The above results suggested that in comparison with coal-derived carbon materials the biomass-derived carbon materials showed better selective reduction of NO_x.