Low-rank coals have been pyrolyzed In high-purity He under different conditions with a fixed bed reactor, and factors controlling N-2 formation have been examined. N-2 is the dominant product at greater than or equal to 800 degrees C after almost complete release of tar-N, HCN, and NH3. Heating rate (10-1400 degrees C/min) affects N-2 slightly. In contrast, conversion of coal-N to N-2 increases remarkably with increasing temperature with a corresponding decrease in char-N and reaches 65-78% at 1200 degrees C. These data lead to a strong, reverse correlation between N-2 and char-N, which shows that char-N and/or precursors are the major source of N-2. Demineralization removes mainly Fe- and Ca-containing minerals and results in a drastic decrease in conversion to N-2. Addition of a nanophase iron catalyst after demineralization promotes N-2 formation, whereas Ca(OH)2 has no significant effect on it. Upon pyrolysis, Fe-containing minerals probably in the ion-exchangeable forms are transformed into fine particles of metallic iron, which are responsible for the remarkable formation of N-2 from low-rank coals. Catalysis by the mineral-derived iron is discussed in terms of interactions with char-N in the solid phase.