This chapter discusses two organometallic iron precursors––ferric acetate and ferrocene––which are impregnated into three coals of different ranks swollen in polar organic solvents. The iron-impregnated coals are subjected to slow atmospheric pyrolysis. The effect of the incorporated iron species on the fate of nitrogen is quantitatively examined. Nitrogen evolved as hydrogen cyanide (HCN), ammonia (NH3), and tar in the initial pyrolysis period is the primary contributor to NOx generated in following combustion stage. Thus, the selective conversion of coal nitrogen into N2 in the pyrolysis stage is effective for suppressing NOx emission. The selective increase of N2 is balanced by the reduction of nitrogen evolved as HCN, tar, and that fixed in char. Iron catalyst precursors is located in micropores prior to pyrolysis to contact the coal matrix at molecular level for promoting pyrolytic removal of coal nitrogen. Brown coals contain much carboxyl groups as cation exchange sites. Iron (Fe3+) ions are easily incorporated into the coal matrix through ion exchange.
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