The coking and cracking behaviour of a heavy oil fraction derived from
Stuart shale oil was investigated in a moving packed-bed reactor. Exp
eriments were performed to evaluate the conversion of heavy oil into l
ower-boiling products, coke and gases when contacted with fully burnt
shale ash and sand. The oil products were characterized by elemental c
omposition, boiling point distribution and n.m.r. spectrometry. The ex
perimental data show wide variations in the stoichiometry, depending o
n the relative contributions of thermal cracking and coking/catalytic
cracking reactions. N.m.r. analyses of the oil products provide insigh
t into the mechanisms of heavy oil coking and cracking. The 1-ene:inte
rnal-ene ratio of the product oil provides a reliable indicator of the
relative importance of these two reactions.