The fate of coal-N in the fixed-bed pyrolysis of 25 coals,with 62-81 wt % (daf) C has been studied with a quartz reactor at 1000 degrees C under ambient pressure to examine the effects of metal cations present naturally in these coals on the partitioning of coal-N into N-2, NH3, HCN, tar-N, and char-N. Nitrogen mass balances for all runs fall within the reasonable range of 100 +/- 5%, and N-2 is the predominant product for all of the coals. As the N-2 yield increases, the sum of NH3, HCN, and tar-N is unchanged significantly, whereas the char-N yield decreases almost linearly, showing that most of N-2 originates from char-N. When eight kinds of inherent metals, such as Na, Mg, Al, Si, K, Ca, Fe, and Ti, are determined by the conventional method and related with the N-2 yield, there exists a strong, direct correlation between the Fe content and N-2 formation for low-rank coals with less than 75 wt % (daf) C. Transmission electron microscopy coupled with an energy-dispersive analysis of X-rays (TEM-EDAX) measurements after pyrolysis at 1000 degrees C of a German brown coal, which provides the highest N-2 yield of about 60%, reveal the existence of lamella structures because of graphitized carbon as well as nanoscale Fe particles with different sizes and shapes. The mechanism for conversion reactions of char-N to N-2 is discussed in terms of the catalysis by nanoparticles of metallic Fe formed from inherent Fe cations.