COMPARATIVE-STUDY OF RESIDUES FROM DRY HYDROGENATION AND LOW-TEMPERATURE PYROLYSIS

Chars from mild pyrolysis and residues from dry, Molybdenum catalyzed hydrogenation, both obtained at 400°C are compared. Structural and compositional features of the samples have been found by several analytical and instrumental techniques. Volumetric swelling in pyridine is used as a measure of the coal network crosslinking produced during the processes. Fluorescence spectroscopy and CP/MAS 13C NMR have also been employed to obtain data on the polyaromatic compounds evolution and functional group distribution. Hydrogenation residues show higher aliphatic content than chars, and higher loss of oxygen-containing groups and heteroatoms, which contributes, among other factors, to a decrease in network crosslinking, as shown by the swelling measurements. Under these conditions both coal derived samples present a similar time evolution of highly condensed structures to less condensed polyaromatic compounds. © 1990.