The structure of five U.S. coals (three of low rank or sub-bituminous
and two of high rank) has been investigated using reactivity criteria
and spectroscopic methods. The results suggest that one of the high-ra
nk coals PSOC 831 contains more cross-linking groups within its macrom
olecular structure than the other high-rank coal DECS 1.2. These cross
-linkages help to explain some previously reported anomalous results r
esulting from reactions of PSOC 831 with hydrogen in the presence of M
oS2. The DECS 9 and PSOC 1379 were shown to be typical low-rank coals
and gave significant ''guest''-derived materials (terpenoid and wax-de
rived hydrocarbons) from pyrolyses at 320 and 350 degrees C, and the s
ub-bituminous coal DECS 6 showed many structural similarities when com
pared with a range of other sub-bituminous coals from Central Queensla
nd, Australia.