In this study

to prepare a series of activated carbon-supported metals for the catalytic reduction of NO

x

to N

2

in excess O

2

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. The effects of the type of biomass

carbonization temperature and catalyst composition on NO

x

reduction efficiency were analyzed in a fixed-bed flow reactor. The results showed that 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 N

2

CO

2

and CO. The influence of the carbonization temperature on carbon reactivity depended on the effect of the carbonization temperature on the carbon surface area and the reduction of the metal species on carbon. All studied metals catalyzed both NO

x

and O

2

reduction by carbon

and potassium could strongly enhance the C-NO

x

reaction without substantial carbon consumption by O

2

. Moreover

the potassium supported by sawdust-derived activated carbon exhibited higher selectivity and capacity towards NO

x

reduction than did 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 the comparison of X-ray photoelectron spectroscopy and powder X-ray diffraction results for the carbons made from biomass and coal-based precursors.