N-15 CPMAS NMR OF THE ARGONNE PREMIUM COALS

N-15 NMR data are reported for the Argonne Premium Coals. Arguments ar e presented to explain discrepancies between observations and conclusi ons obtained from NMR experiments and those obtained by XPS and XANES techniques. Detectability of different types of nitrogens is discussed in terms of cross-polarization dynamics together with the effects of the large chemical shift anisotropy that is found in different types o f nitrogen functional groups. Data on acid-treated coals confirm the p resence of pyridinic type nitrogens that were not observed in a previo us N-15 NMR study of coals.