QUANTIFICATION OF NITROGEN FORMS IN ARGONNE PREMIUM COALS

X-ray photoelectron spectroscopy (XPS) was used to identify and quantify the organically bound nitrogen forms present in fresh Argonne Premium coals. XPS spectra obtained on a wide variety of model compounds were used to establish a curve resolution methodology. Pyrrolic nitrogen is the most abundant form of organically bound nitrogen, followed by pyridinic types. Quaternary nitrogen species were also identified. An analysis of the sensitivity of XPS for primary amines indicates that these species are not detected at concentrations above 5 mol %. A trend of decreasing level of quaternary nitrogen forms along with increasing levels of pyridinic nitrogen was observed with increasing coal rank. The formation and reactivity of quaternary nitrogen forms in several coals were examined. Quaternary nitrogen forms decrease upon pyrolysis and hydropyrolysis. The level of quaternary nitrogen increases upon treating high-rank coal with strong acid.