The hydrotreatment of PR Spring bitumen-derived heavy oils was achieve
d in a fixed-bed reactor over presulfided commercial NiMo/alumina hydr
odenitrogenation catalysts. The extents of heteroatom and metal remova
l and of Conradson carbon residue (CCR) and residuum ( > 811 K) conver
sion were determined as a function of process operating variables: tem
perature (625-685 K) and liquid hourly space velocity (0.14-0.80 h(-1)
). Pressure and hydrogen/oil ratio were fixed at 13.7 MPa and 890 m(3)
m(-3) in all experiments. Differences between heteroatom removal and
residuum conversion and between CCR conversion and metal removal were
investigated and product distributions and yields were studied. The de
gree of Ni, N and S removal and of CCR and residuum conversion increas
ed significantly as reciprocal LHSV and temperature increased. The res
iduum fraction ( > 811 K) became significantly converted with increasi
ng residence time and the yields of gas oil (617-811 K), distillate (4
77-617 K), naphtha (i.b.p.-477 K) and C-1-C-4 gases increased continuo
usly. Residuum was significantly converted to volatiles at higher temp
eratures. The yields of distillate, naphtha and gas increased rapidly
at higher temperatures. (C) 1997 Elsevier Science Ltd.