H-1 CRAMPS NMR DERIVED HYDROGEN DISTRIBUTIONS IN VARIOUS COAL MACERALS

The distribution of protons bonded to sp2 and sp3 hybridized carbons in a number of macerals including liptinites and inertinites, has been investigated by C-13 cross polarization magic angle spinning (CP/MAS) and H-1 combined rotation and multiple pulse nuclear magnetic resonance spectroscopy (CRAMPS). Some preliminary H-1-C-13 solid state heterocorrelation spectra of coals and one maceral have also been obtained. CRAMPS was only successful in resolving acidic, aromatic/alkenic, carbohydrate and aliphatic protons in the macerals. The semifusinites had variable (0.38-->0.58) proton aromaticities and (0.40-->0.84) carbon aromaticities, and the liptinite macerals had a low (0.06) fraction of protons attached to sp2 hybridized carbon. Of the nine resinite samples examined, one (Hornerstown) was clearly identified to be a naturally occurring polymer of styrene. The CRAMPS spectra of the other seven were useful, identifying them as carboxylic acids. Two dimensional H-1-C-13 heteronuclear solid state spectroscopy was successful in resolving two types of aliphatic hydrogen in the selected coals studied, with longer range coupling able to be observed in the structurally simpler Hornerstown resinite by implementation of two WIM-24 cross-polarization cycles.