Solid-state N-15 NMR is applied in a study of various coal samples to
evaluate the forms of nitrogen in coal. The spectra display the main s
ignal intensities in the region of pyrrole-and indole derivatives, No
signals assigned to pyridine derivatives were identified. This contrad
icts the most common belief that pyridine-like structures comprise the
major form of nitrogen in coal. The successful application of N-15 NM
R spectroscopy to coal samples may help to provide a new level of unde
rstanding of coal-nitrogen chemistry.