INFLUENCE OF HYDROGEN AND CATALYST ON DISTILLATE YIELDS AND THE REMOVAL OF HETEROATOMS, AROMATICS, AND CCR DURING CRACKING OF ATHABASCA BITUMEN RESIDUUM OVER A WIDE-RANGE OF CONVERSIONS
Ec. Sanford, INFLUENCE OF HYDROGEN AND CATALYST ON DISTILLATE YIELDS AND THE REMOVAL OF HETEROATOMS, AROMATICS, AND CCR DURING CRACKING OF ATHABASCA BITUMEN RESIDUUM OVER A WIDE-RANGE OF CONVERSIONS, Energy & fuels, 8(6), 1994, pp. 1276-1288
The percent conversion of sulfur, nitrogen, vanadium, nickel, aromatic
s, and CCR (Conradson carbon residue) has been analyzed as a function
of residuum conversion for five series of reactions carried out in a b
atch reactor under nitrogen, hydrogen, or hydrogen in the presence of
a residuum hydrotreating catalyst, over residuum conversions ranging f
rom 38 to 86%. Sulfur, nitrogen, and CCR conversions could be divided
into three categories, up to 50% residuum conversion, 50-70% residuum
conversion, and greater than 70% residuum conversion. Sulfur conversio
n in the first category was from the distillable liquids and resulted
from a combination of thermal, hydrogenation, and hydrogen atom additi
on reactions. Nitrogen removal in the first category was due to incorp
oration of nitrogen into reactor solids in the early stages of the rea
ction and was therefore suppressed by hydrogen in the absence of a cat
alyst. In the presence of hydrogen, CCR conversion was largely due to
hydrogen atom addition. Without hydrogen, CCR conversion was negative
through the first two categories of conversion. Aromatics in the resid
ua fractions increased steadily as residuum Conversion increased, but
increased faster in the coking case. Sulfur, nitrogen, and CCR convers
ions were all rapid after approximately 70% residuum conversion and we
re explained in terms of thermal reactions. Metals removal appeared to
be due to thermal reactions with the solids in the reactor acting as
a collector. Catalytic reactions did not appear to play a role. Overal
l, the main role of catalyst was the removal of sulfur from distillabl
e liquids produced in the early stages of the residuum conversion reac
tion, and in CCR conversion, again in the early stages of the reaction
.