Note: Descriptions are shown in the official language in which they were submitted.
CA 02727167 2014-07-17
CATALYST COMPOSITION WITH NANOMETER CRYSTALLITES
FOR SLURRY HYDROCRACKING
BACKGROUND OF THE INVENTION
[0001] This invention relates to a process and apparatus for the
treatment of crude oils
and, more particularly, to the hydroconversion of heavy hydrocarbons in the
presence of
additives and catalysts to provide useable products and further prepare
feedstock for further
refining.
[0002] As the reserves of conventional crude oils decline, heavy oils
must be upgraded to
meet world demands. In heavy oil upgrading, heavier materials are converted to
lighter
fractions and most of the sulfur, nitrogen and metals must be removed. Heavy
oils include
materials such as petroleum crude oil, atmospheric tower bottoms products,
vacuum tower
bottoms products, heavy cycle oils, shale oils, coal derived liquids, crude
oil residuum,
topped crude oils and the heavy bituminous oils extracted from oil sands. Of
particular
interest are the oils extracted from oil sands and which contain wide boiling
range materials
from naphthas through kerosene, gas oil, pitch, etc., and which contain a
large portion of
material boiling above 524 C. These heavy hydrocarbon feedstocks may be
characterized by
low reactivity in visbreaking, high coking tendency, poor susceptibility to
hydrocracking and
difficulties in distillation. Most residual oil feedstocks which are to be
upgraded contain some
level of asphaltenes which are typically understood to be heptane insoluble
compounds as
determined by ASTM D3279 or ASTM D6560. Asphaltenes are high molecular weight
compounds containing heteroatoms which impart polarity.
[0003] Heavy oils must be upgraded in a primary upgrading unit before it
can be further
processed into useable products. Primary upgrading units known in the art
include, but are
not restricted to, coking processes, such as delayed or fluidized coking, and
hydrogen
addition processes such as ebullated bed or slurry hydrocracking (SHC). As an
example, the
yield of liquid products, at room temperature, from the coking of some
Canadian bitumens is
typically 55 to 60 wt-% with substantial amounts of coke as by-product. On
similar feeds,
ebullated bed hydrocracking typically produces liquid yields of 50 to 55 wt-%.
US 5,755,955
describes a SHC process which has been found to provide liquid yields of 75 to
80 wt-% with
much reduced coke formation through the use of additives.
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[0004] In SHC, a three-phase mixture of heavy liquid oil feed cracks in
the presence of
gaseous hydrogen over solid catalyst to produce lighter products under
pressure at an
elevated temperature. Iron sulfate has been disclosed as an SHC catalyst, for
example, in US
5,755,955. Iron sulfate monohydrate is typically ground down to smaller size
for better
dispersion and facilitation of mass transfer. Iron sulfate (FeSO4) usually
requires careful
thermal treatment in air to remove water from iron sulfate which is typically
provided in a
hydrated form. Water can inhibit conversion of FeSO4 to iron sulfide and
typically must be
removed. It is thought that iron sulfate monohydrate decomposes slowly in an
SHC to form
iron sulfide. Drying the iron sulfate monohydrate in-situ initially dehydrates
to FeSO4 as
shown in Formula (1). However, FeSO4 also rehydrates to the monohydrate during
its
decomposition to form iron sulfide in Formula (2). Ultimately, FeSO4 converts
to iron
sulfide as shown in Formula (3):
2Fe (SO4).1420 + 8H2 2Fe(SO4) + 2H20 +8H2 (I)
2Fe(SO4) + 2H20 +8H2 FeS + Fe(SO4).12120 +4H20 +4H2 (2)
FeS + Fe(SO4)+120 +4H20 2FeS + 10H20 (3)
Consequently, the amount of water in the system may limit the rate at which
iron sulfide can
form. Thermal treatment also removes volatiles such as carbon dioxide to make
the catalyst
denser and opens up the pores in the catalyst to make it more active.
[0005] Iron sulfate already contains sulfur. The thermal treatment
converts the iron in
iron sulfate to catalytically active iron sulfide. The sulfur from iron
sulfate contributes to the
sulfur in the product that has to be removed. Other iron containing catalysts
such as limonite,
which contains Fe0(OH)-n1-I20, require presulfide treatment for better
dispersion and
conversion of the iron oxide to the active iron sulfide according to CA
2,426,374. Presulfide
treatment adds sulfur to the catalyst and consequently to the heavy
hydrocarbon being
processed. As such, extra sulfur must usually be removed from the product. The
active iron
in the +2 oxidation state in the iron sulfide catalyst is required to obtain
adequate conversion
and selectivity to useful liquids and to avoid higher coke formation. US
4,591,426 mentions
bauxite without examining it and exemplifies limonite and laterite as
catalysts. SHC catalysts
are typically ground to a very small particle diameter to facilitate
dispersion and promote
mass transfer.
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[0006] During an SHC reaction, it is important to minimize coking. It
has been shown by
the model of Pfeiffer and Saal, PHYS. CHEM. 44, 139 (1940), that asphaltenes
are surrounded
by a layer of resins, or polar aromatics which stabilize them in colloidal
suspension. In the
absence of polar aromatics, or if polar aromatics are diluted by paraffinic
molecules or are
converted to lighter paraffinic and aromatic materials, these asphaltenes can
self-associate, or
flocculate to form larger molecules, generate a mesophase and precipitate out
of solution to
form coke.
[0007] Toluene can be used as a solvent to dissolve to separate
carbonaceous solids from
lighter hydrocarbons in the SHC product. The solids not dissolved by toluene
include catalyst
and toluene insoluble organic residue (TIOR). TIOR includes coke and mesophase
and is
heavier and less soluble than asphaltenes which are soluble in heptane.
Mesophase formation
is a critical reaction constraint in slurry hydrocracking reactions. Mesophase
is a semi-
crystalline carbonaceous material defined as round, anisotropic particles
present in pitch
boiling above 524 C. The presence of mesophase can serve as a warning that
operating
conditions are too severe in an SHC and that coke formation is likely to occur
under
prevailing conditions.
SUMMARY OF THE INVENTION
[0008] We have found that nanometer-sized iron sulfide crystallites
provide superior
conversion in a SHC reaction. The iron sulfide crystallites are typically the
same size as the
iron sulfide precursor crystallites from which they are produced. In bauxite,
the iron sulfide
precursor crystallite is iron oxide. By not thermally treating the iron
sulfide precursor prior to
the SHC, iron sulfide precursor crystallites do not sinter together and become
larger, thereby
allowing the catalytically active iron sulfide crystallites to remain in the
nanometer range.
[0008.1] In accordance with one aspect of the present invention, there is
provided a
composition comprising a catalyst comprising iron sulfide crystallites with a
mean diameter
of about 1 to about 150 nanometers, and heavy hydrocarbon medium, wherein the
catalyst is
dispersed in the heavy hydrocarbon medium and the iron sulfide crystallites
comprising no
less than 99 wt-% FexS, where x is between 0.7 and 1.3.
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[0008.2] In accordance with another aspect of the present invention, there is
provided a
composition comprising a catalyst comprising iron sulfide crystallites with a
mean diameter
of about 1 to about 25 nanometers as determined by XRD, and heavy hydrocarbon
medium,
wherein the catalyst is dispersed in the heavy hydrocarbon.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] For a better understanding of the invention, reference is made to
the
accompanying drawings.
[0010] FIG. 1 is a schematic flow scheme for a SHC plant.
[0011] FIG. 2 is a plot of an XRD of a sample of TIOR with the peaks in
the hydrocarbon
region shaded.
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[0012] FIG. 3 is a plot of an XRD of a sample of TIOR with the non-
mesophase peaks
shaded in the hydrocarbon region.
[0013] FIG. 4 is a series of XRD plots for TIOR made with iron sulfate
catalyst.
[0014] FIG. 5 is a series of XRD plots for TIOR made with the catalyst
of the present
invention.
[0015] FIG. 6 is an XRD plot for TIOR made with iron sulfide
monohydrate catalyst.
[0016] FIG. 7 is a SEM micrograph of iron sulfide monohydrate catalyst.
[0017] FIG. 8 is an XRD plot for TIOR made with limonite catalyst.
[0018] FIG. 9 is a SEM micrograph of limonite catalyst.
[0019] FIG. 10 is an XRD plot for TIOR made with bauxite catalyst.
[0020] FIG. 11 is a STEM micrograph of bauxite catalyst.
[00211 FIG. 12 is a PLM micrograph of TIOR made with iron sulfide
monohydrate
catalyst.
[0022] FIG. 13 is a PLM micrograph of TIOR made with limonite catalyst.
[0023] FIG. 14 is a PLM micrograph of TIOR made with bauxite catalyst.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] The process and apparatus of this invention is capable of
processing a wide range
of heavy hydrocarbon feedstocks. It can process aromatic feedstocks, as well
as feedstocks
which have traditionally been very difficult to hydroprocess, e.g. vacuum
bottoms, visbroken
vacuum residue, deasphalted bottom materials, off-specification asphalt,
sediment from the
bottom of oil storage tanks, etc. Suitable feeds include atmospheric residue
boiling at 650 F
(343 C), heavy vacuum gas oil (VGO) and vacuum residue boiling at 800 F (426
C) and
vacuum residue boiling above 950 F (510 C). Throughout this specification, the
boiling
temperatures are understood to be the atmospheric equivalent boiling point
(AEBP) as
calculated from the observed boiling temperature and the distillation
pressure, for example
using the equations furnished in ASTM D1160. Furthermore, the tem" "pitch" is
understood
to refer vacuum residue, or material having an AEBP of greater than 975 F (524
C). Feeds of
which 90 wt-% boils at a temperature greater than or equal to 572 F (300 C)
will be suitable.
Suitable feeds include an API gravity of no more than 20 degrees, typically no
more than 10
degrees and may include feeds with less than 5 degrees.
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[0025] In the exemplary SHC process as shown in FIG. 1, one, two or all
of a heavy
hydrocarbon oil feed in line 8, a recycle pitch stream containing catalyst
particles in line 39,
and recycled heavy VG0 in line 37 may be combined in line 10. The combined
feed in line
is heated in the heater 32 and pumped through an inlet line 12 into an inlet
in the bottom
5 of the tubular SHC reactor 13. Solid particulate catalyst material may be
added directly to
heavy hydrocarbon oil feed in the SHC reactor 13 from line 6 or may be mixed
from line 6'
with a heavy hydrocarbon oil feed in line 12 before entering the reactor 13 to
form a slurry in
the reactor 13. It is not necessary and may be disadvantageous to add the
catalyst upstream of
the heater 32. It is possible that in the heater, iron particles may sinter or
agglomerate to make
10 larger iron particles, which is to be avoided. Many mixing and pumping
arrangements may be
suitable. It is also contemplated that feed streams may be added separately to
the SHC reactor
13. Recycled hydrogen and make up hydrogen from line 30 are fed into the SHC
reactor 13
through line 14 after undergoing heating in heater 31. The hydrogen in line 14
that is not
premixed with feed may be added at a location above the feed entry in line 12.
Both feed
from line 12 and hydrogen in line 14 may be distributed in the SHC reactor 13
with an
appropriate distributor. Additionally, hydrogen may be added to the feed in
line 10 before it
is heated in heater 32 and delivered to the SHC reactor in line 12. Preferably
the recycled
pitch stream in line 39 makes up in the range of 5 to 15 wt-% of the feedstock
to the SHC
reactor 13, while the heavy VG0 in line 37 makes up in the range of 5 to 50 wt-
% of the
feedstock, depending upon the quality of the feedstock and the once-through
conversion
level. The feed entering the SHC reactor 13 comprises three phases, solid
catalyst particles,
liquid and solid hydrocarbon feed and gaseous hydrogen and vaporized
hydrocarbon.
[0026] The process of this invention can be operated at quite moderate
pressure, in the
range of 500 to 3500 psi (3.5 to 24 MPa) and preferably in the range o 1500 to
2500 psi (10.3
to 17.2 MPa), without coke formation in the SHC reactor 13. The reactor
temperature is
typically in the range of 400 to 500 C with a temperature of 440 to 465 C
being suitable
and a range of 445 to 460 C being preferred. The LHSV is typically below 4 hr-
I on a fresh
feed basis, with a range of 0.1 to 3 hi.- I being preferred and a range of 0.3
to 1 hr-I being
particularly preferred. Although SHC can be carried out in a variety of known
reactors of
either up or downflow, it is particularly well suited to a tubular reactor
through which feed,
catalyst and gas move upwardly. Hence, the outlet from SHC reactor 13 is above
the inlet.
Although only one is shown in the FIG. 1, one or more SHC reactors 13 may be
utilized in
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parallel or in series. Because the liquid feed is converted to vaporous
product, foaming tends to
occur in the SHC reactor 13. An antifoaming agent may also be added to the SHC
reactor 13,
preferably to the top thereof, to reduce the tendency to generate foam.
Suitable antifoaming
agents include silicones as disclosed in US 4,969,988.
[0027] A gas-liquid mixture is withdrawn from the top of the SHC reactor 13
through line 15
and separated preferably in a hot, high-pressure separator 20 kept at a
separation temperature
between 2000 and 470 C (392 and 878 F) and preferably at the pressure of the
SHC reactor. In
the hot separator 20, the effluent from the SHC reactor 13 is separated into a
gaseous stream 18
and a liquid stream 16. The liquid stream 16 contains heavy VGO. The gaseous
stream 18
comprises between 35 and 80 vol-% of the hydrocarbon product from the SHC
reactor 13 and is
further processed to recover hydrocarbons and hydrogen for recycle.
[0028] A liquid portion of the product from the hot separator 20 may be used
to form the
recycle stream to the SHC reactor 13 after separation which may occur in a
liquid vacuum
fractionation column 24. Line 16 introduces the liquid fraction from the hot
high pressure
separator 20 preferably to a vacuum distillation column 24 maintained at a
pressure between
0.25 and 1.5 psi (1.7 and 10.0 kPa) and at a vacuum distillation temperature
resulting in an
atmospheric equivalent cut point between light VGO and heavy VGO of between
250 and
500 C (482 and 932 F). Three fractions may be separated in the liquid
fractionation column:
an overhead fraction of light VGO in an overhead line 38 which may be further
processed, a
heavy VGO stream from a side cut in line 29 and a pitch stream obtained in a
bottoms line 40
which typically boils above 450 C. At least a portion of this pitch stream may
be recycled back
in line 39 to form part of the feed slurry to the SHC reactor 13. Remaining
catalyst particles
from SHC reactor 13 will be present in the pitch stream and may be
conveniently recycled back
to the SHC reactor 13. Any remaining portion of the pitch stream is recovered
in line 41. During
the SHC reaction, it is important to minimize coking. Adding a lower polarity
aromatic oil to the
feedstock reduces coke production. The polar aromatic material may come from a
wide variety
of sources. A portion of the heavy VGO in line 29 may be recycled by line 37
to form part of
the feed slurry to the SHC reactor 13. The remaining portion of the heavy VGO
may be
recovered in line 35.
[0029] The gaseous stream in line 18 typically contains lower concentrations
of aromatic
components than the liquid fraction in line 16 and may be in need of further
refining. The gaseous
stream in line 18 may be passed in line 21 to a catalytic hydrotreating
reactor 44 having a bed
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charged with hydrotreating catalyst. If necessary, additional hydrogen may be
added to the
stream in line 18. Suitable hydrotreating catalysts for use in the present
invention are any
known conventional hydrotreating catalysts and include those which are
comprised of at least
one Group VIII metal and at least one Group VI metal on a high surface area
support
material, such as a refractory oxide. The gaseous stream is contacted with the
hydrotreating
catalyst at a temperature between 2000 and 600 C (430 and 1112 F) in the
presence of
hydrogen at a pressure between 5.4 and 34.5 MPa (800 and 5000 psia). The
hydrotreated
product from the hydrotreating reactor 44 may be withdrawn through line 46.
[0030] The effluent from the hydrotreating reactor 44 in line 46 may be
delivered to a
cool high pressure separator 19. Within the cool separator 19, the product is
separated into a
gaseous stream rich in hydrogen which is drawn off through the overhead in
line 22 and a
liquid hydrocarbon product which is drawn off the bottom through line 28. The
hydrogen-rich
stream 22 may be passed through a packed scrubbing tower 23 where it is
scrubbed by means
of a scrubbing liquid in line 25 to remove hydrogen sulfide and ammonia. The
spent
scrubbing liquid in line 27 may be regenerated and recycled and is usually an
amine. The
scrubbed hydrogen-rich stream emerges from the scrubber via line 34 and is
combined with
fresh make-up hydrogen added through line 33 and recycled through a recycle
gas
compressor 36 and line 30 back to reactor 13. The bottoms line 28 may carry
liquid
hydrotreated product to a product fractionator 26.
[0031] The product fractionator 26 may comprise one or several vessels
although it is
shown only as one in FIG. 1. The product fractionator produces a C4- recovered
in overhead
line 52, a naphtha product stream in line 54, a diesel stream in line 56 and a
light VGO
stream in bottoms line 58.
[0032] We have discovered that catalyst particles comprising between 2
and 45 wt-% iron
oxide and between 20 and 90 wt-% alumina make excellent SHC catalysts. Iron-
containing
bauxite is a preferred bulk available mineral having these proportions.
Bauxite typically has
10 to 40 wt-% iron oxide, Fe203, and 54 to 84 wt-% alumina and may have 10 to
35 wt-%
iron oxide and 55 to 80 wt-% alumina. Bauxite also may comprise silica, Si02,
and titania,
Ti02, in aggregate amounts of usually no more than 10 wt-% and typically in
aggregate
amounts of no more than 6 wt-%. Iron is present in bauxite as iron oxide and
aluminum is
present in bauxite as alumina. Volatiles such as water and carbon dioxide are
also present in
bulk available minerals, but the foregoing weight proportions exclude the
volatiles. Iron
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oxide is also present in bauxite in a hydrated form, Fe203.nH20. Again, the
foregoing
proportions exclude the water in the hydrated composition.
[0033] Bauxite can be mined and ground to particles having a mean
particle diameter of
0.1 to 5 microns. The particle diameter is the length of the largest
orthogonal axis through the
particle. We have found that alumina and iron oxide catalysts with mean
particle diameters
of no less than 200 microns, using the dry method to determine particle
diameter, exhibit
performance comparable to the performance of the same catalyst ground down to
the 0.1 to 5
micron range. Hence, alumina and iron oxide catalysts with mean particle
diameters of no
less than 200 microns, suitably no less than 249 microns and preferably no
less than 250
microns can be use to promote SHC reactions. In an embodiment the catalyst
should not
exceed 600 microns and preferably will not exceed 554 microns in terms of mean
particle
diameter using the dry method to determine particle diameter. Mean particle
diameter is the
average particle diameter of all the catalyst particles fed to the reactor
which may be
determined by a representative sampling. Consequently, less effort must be
expended to
grind the catalyst particles to smaller diameters for promoting SHC,
substantially reducing
time and expense. Particle size determinations were made using a dry method
which more
closely replicates how the bulk catalyst will initially encounter hydrocarbon
feed. A wet
method for determining particle diameters appeared to break particles of
bauxite into smaller
particles which may indicate what occurs upon introduction of catalyst into an
SHC reactor.
[0034] The alumina in the catalyst can be in several forms including alpha,
gamma, theta,
boehmite, pseudo-boehmite, gibbsite, diaspore, bayerite, nordstrandite and
corundum.
Alumina can be provided in the catalyst by derivatives such as spinels and
perovskites.
Suitable bauxite is available from Saint-Gobain Norpro in Stow, Ohio who may
provide it air
dried and ground, but these treatments may not be necessary for suitable
performance as a
catalyst for SHC.
[0035] We have found that these alumina and iron oxide containing
catalyst particles are
more effective if they are not first subjected to a thermal treatment or a
sulfide treatment. We
have also found that water does not impede formation of active iron sulfide
from iron oxide
in bauxite, so it is not required to remove water by the thermal or any other
drying treatment.
The water on the catalyst can be either chemically bound to the iron oxide,
alumina or other
components of the catalyst or be physically bound to the catalyst. More than
23 wt-% water
can be present on the catalyst without affecting the performance of the
catalyst. We have
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found that 39 wt-% water does not affect performance of the catalyst and would
expect up to
at least 40 wt-% water on the catalyst would not affect performance. Water on
catalyst can
be determined by loss on ignition (LOI), which involves heating the catalyst
to elevated
temperature such as 900 C. All volatiles come off in addition to water but the
non-water
volatiles were not significant.
[00361 The iron in iron oxide in the presence of alumina such as in
bauxite quickly
converts to active iron sulfide without the need for presenting excess sulfur
to the catalyst in
the presence of heavy hydrocarbon feed and hydrogen at high temperature as
required for
other SHC catalysts before addition to the reaction zone. The iron sulfide has
several
molecular forms, so is generally represented by the formula, Fe,S, where x is
between 0.7
and 1.3. We have found that essentially all of the iron oxide converts to iron
sulfide upon
heating the mixture of hydrocarbon and catalyst to 410 C in the presence of
hydrogen and
sulfur. In this context, "essentially all" means no peak for iron oxide is
generated on an XRD
plot of intensity vs. two theta degrees at 33.1 two theta degrees or no less
than 99 wt-%
conversion to iron sulfide. Sulfur may be present in the hydrocarbon feed as
organic sulfur
compounds. Consequently, the iron in the catalyst may be added to the heavy
hydrocarbon
feed in the +3 oxidation state, preferably as Fe203. The catalyst may be added
to the feed in
the reaction zone or prior to entry into the reaction zone without
pretreatment. After mixing
the iron oxide and alumina catalyst with the heavy hydrocarbon feed which
comprises
organic sulfur compounds and heating the mixture to reaction temperature,
organic sulfur
compounds in the feed convert to hydrogen sulfide and sulfur-free
hydrocarbons. The iron in
the +3 oxidation state in the catalyst quickly reacts at reaction temperature
with hydrogen
sulfide produced in the reaction zone by the reaction of organic sulfur and
hydrogen. The
reaction of iron oxide and hydrogen sulfide produce iron sulfide which is the
active form of
the catalyst. Iron is then present in the +2 oxidation state in the reactor.
The efficiency of
conversion of iron oxide to iron sulfide enables operation without adding
sulfur to the feed if
sufficient available sulfur is present in the feed to ensure complete
conversion to iron sulfide.
Otherwise, sulfur may be added for low sulfur feeds if necessary to convert
all the iron oxide
to iron sulfide. Because the iron oxide and alumina catalyst is so efficient
in converting iron
oxide to iron sulfide and in promoting the SHC reaction, less iron must be
added to the SHC
reactor. Consequently, less sulfur is required to convert the iron oxide to
iron sulfide
minimizing the need for sulfur addition. The iron oxide and alumina catalyst
does not have to
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be subjected to elevated temperature in the presence of hydrogen to obtain
conversion to iron
sulfide. Conversion occurs at below SHC reaction temperature. By avoiding thet
mal and
sulfiding pretreatments, process simplification and material cost reduction
are achieved.
Additionally, less hydrogen is required and less hydrogen sulfide and other
sulfur must be
removed from the SHC product.
[0037] Several terms are noteworthy in the characterization of
performance of the iron
oxide and alumina catalysts in SHC. "Iron content" is the weight ratio of iron
on the catalyst
relative to the non-gas materials in the SHC reactor. The non-gas materials in
the reactor are
typically the hydrocarbon liquids and solids and the catalyst and do not
include reactor and
ancillary equipment. "Aluminum content" is the weight ratio of aluminum
relative to the non-
gas materials in the in the SHC reactor. "Pitch conversion" is the weight
ratio of material
boiling at or below 524 C in the product relative to the material boiling
above 524 C in the
feed. "C5-524 C yield" is the weight ratio of material in the product boiling
in the C5 boiling
range to 524 C relative to the total hydrocarbon feed. "TIOR" is the toluene-
insoluble
organic residue which represents non-catalytic solids in the product part
boiling over 524 C.
"Mesophase" is a component of TIOR that signifies the existence of coke,
another component
of TIOR. "API gravity index" is a parameter that represents the flowability of
the material.
Mean particle or crystallite diameter is understood to mean the same as the
average particle
or crystallite diameter and includes all of the particles or crystallites in
the sample,
respectively.
[0038] Iron content of catalyst in an SHC reactor is typically 0.1 to
4.0 wt-% and usually
no more than 2.0 wt-% of the catalyst and liquid in the SHC. Because the iron
in the presence
of alumina, such as in bauxite, is very effective in quickly producing iron
sulfide crystallites
from the sulfur in the hydrocarbon feed, less iron on the iron oxide and
alumina catalyst is
necessary to promote adequate conversion of heavy hydrocarbon feed in the SHC
reactor.
The iron content of catalyst in the reactor may be effective at concentrations
below or at 1.57
wt-%, suitably no more than 1 wt-%, and preferably no more than 0.7 wt-%
relative to the
non-gas material in the reactor. In an embodiment, the iron content of
catalyst in the reactor
should be at least 0.4 wt-%. Other bulk available minerals that contain iron
were not able to
perform as well as iron oxide and alumina catalyst in the form of bauxite in
terms of pitch
conversion, C5-524 C yield, TIOR yield and mesophase yield. At 2 wt-% iron,
limonite was
comparable to bauxite only after being subjected to extensive pretreatment
with sulfide, after
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which the limonite produced too much mesophase yield. At the low concentration
of 0.7
wt-% iron on the catalyst in the reactor, no catalyst tested performed as well
as iron oxide and
alumina catalyst while suppressing TIOR and mesophase yield. At around 1 and
1.5 wt-%
iron content in the reactor, bauxite performed better than iron sulfate
monohydrate and
limonite. We have further found that the resulting product catalyzed by the
iron oxide and
alumina catalyst can achieve an API gravity of at least four times that of the
feed, as much as
six times that of the feed and over 24 times that of the feed indicating
excellent conversion of
heavy hydrocarbons. Use of iron oxide an alumina catalyst like bauxite allows
superior
conversion of heavy hydrocarbon feed to desirable products with less catalyst
and trace or no
generation of mesophase which signifies coke generation.
[0039] The presence of alumina on the iron containing catalyst has a
beneficial effect on
performance. Alumina combined with other iron containing catalyst improves
performance in
a SHC reaction, particularly in the suppression of mesophase production.
Naturally occurring
bauxite has better performance than other iron and aluminum containing
catalysts. A suitable
aluminum content on the catalyst is 0.1 to 20 wt-% relative to non-gas solids
in the reactor.
An aluminum content of no more than 10 wt-% may be preferred.
[0040] The crystallites of iron sulfide generated by bauxite in the
reactor at reaction
conditions have diameters across the crystallite in the in the nanometer
range. An iron sulfide
crystal is a solid in which the constituent iron sulfide molecules are packed
in a regularly
ordered, repeating pattern extending in all three spatial dimensions. An iron
sulfide
crystalliteis a domain of solid-state matter that has the same structure as a
single iron sulfide
crystal. Nanometer-sized iron sulfide crystallites disperse well over the
catalyst and disperse
well in the reaction liquid. The iron sulfide crystallites are typically about
the same size as the
iron sulfide precursor crystallites from which they are produced. In bauxite,
the iron sulfide
precursor crystallite is iron oxide. By not thermally treating the bauxite,
iron oxide crystals do
not sinter together and become larger. Consequently, the catalytically active
iron sulfide
crystallites produced from the iron oxide remain in the nanometer range. The
iron sulfide
crystallites may have an average largest diameter between 1 and 150 nm,
typically no more
than 100 nm, suitably no more than 75 nm, preferably no more than 50 nm, more
preferably
no more than 40 nm as determined by electron microscopy. The iron sulfide
crystallites
suitably have a mean crystallite diameter of no less than 5 nm, preferably no
less than 10 nm
and most preferably no less than 15 nm as determined by electron microscopy.
Electron
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microscopy reveals that the iron sulfide crystallites are fairly uniform in
diameter, well
dispersed and predominantly present as single crystals. Use of XRD to
determine iron sulfide
crystallite size yields smaller crystallite sizes which is perhaps due to
varying iron to sulfur
atomic ratios present in the iron sulfide providing peaks near the same two
theta degrees.
XRD reveals iron sulfide crystallite mean diameters of between 1 and 25 nm,
preferably
between 5 and 15 nm and most preferably between 9 and 12 nm. Upon conversion
of the iron
oxide to iron sulfide, for example, in the reactor, a composition of matter
comprising 2 to 45
wt-% iron sulfide and 20 to 98 wt-% alumina is generated and dispersed in the
heavy
hydrocarbon medium to provide a slurry. The composition of matter has iron
sulfide
crystallites in the nanometer range as just described. We have found that the
iron oxide
precursor crystallites in bauxite have about the same particle diameter as the
iron sulfide
crystallites folmed from reaction with sulfur. We have further found that the
alumina and
iron oxide catalyst can be recycled to the SHC reactor at least twice without
iron sulfide
crystallites becoming larger.
[0041] Cross polarized light microscopy (PLM) may be used to identify the
mesophase
structure and quantify mesophase concentration in TIOR from SHC reactions
using ASTM D
4616-95. The semi-crystalline nature of mesophase makes it optically active
under cross
polarized light. TIOR samples are collected, embedded in epoxy and polished.
The relative
amounts of mesophase can be quantified using PLM to generate an image from the
sample
and identifying and counting mesophase in the PLM image.
[0042] We have also found that this semi-crystalline nature of
mesophase also allows it to
appear in an XRD pattern. We have found that the presence of mesophase is
indicated by a
peak at 26 two theta degrees, within 0.3 and preferably within 0.2 in an
XRD pattern.
This mesophase peak found in XRD images correlates with the mesophase found by
PLM.
We have found the broad feature in the range between 20 and 29.5 two theta
degrees can be
associated with mesophase.
[0043] To analyze a sample for mesophase, a sample of hydrocarbon
material is blended
with a solvent such as toluene, centrifuged and the liquid phase decanted.
These steps can be
repeated. The solids may then be dried in a vacuum oven such as at 90 C for 2
hours. At this
point the dried sample is ready for mesophase identification either by PLM or
by XRD. For
XRD, a standard such as silicon is worked into the solids sample along with a
solvent such as
acetone to form a slurry to enable mixing the standard with the sample. The
solvent should
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CA 02727167 2014-07-17
quickly evaporate leaving the sample with a predetermined concentration of
standard.
Approximately 1 gram of sample with standard is spread onto a XRD sample
holder and placed
into the XRD instrument such as a ScintagTM XDS-2000 XRD instrument and
scanned using
predetermined range parameters. Scan range parameters such as
2.0/70.0/0.02/0.6(sec) and
2.0/70.0/0.04/10(sec) are suitable. Other parameters may be suitable. The
resulting data is
plotted, for example, by using JADETM software from Materials Data, Inc. in
Livermore,
California, which may be loaded on the XRD instrument. The JADE software uses
International
Center for Diffraction Data (ICDD) as a database of standards for phase
identification and
automated search-match functions.
[00441 To calculate the mesophase concentration, the aggregate area of the
peaks in the total
carbon region from 200 2-theta degrees to the right most edge of a silicon
peak at 28.5 two
theta degrees should be calculated. The right most edge of the silicon peak is
at 29.5 two theta
degrees. If a standard other than silicon is used, the total carbon region
should be calculated to
include up to 29.5 two theta degrees. Parts of the broad feature of a
mesophase peak may lie in
this total carbon region. In the JADE software, the Peak Paint function can be
used to obtain the
peak area for the total carbon region from an XRD pattern. The total carbon
region contains a
mesophase peak at 26 two theta degrees if mesophase is present and a silicon
peak at 28.5 two
theta from a silicon standard added to the sample. Once the aggregate area of
the peaks in the
total carbon region is determined, the non-mesophase peaks in the total carbon
region may be
identified and their total area along with the area of the silicon peak
calculated and subtracted
from the aggregate area of the peaks in the total carbon region peak to
provide the area of the
mesophase peak. The non-mesophase peaks in the total carbon region can be
identified using
the JADE software which matches peak patterns in the plot to standard peak
patterns in the
ICDD database. Bauxite, for example, typically includes titania which provides
a peak at 26.2
two theta degrees. Other non-mesophase may be identified to subtract the
corresponding peak
area from the mesophase peak area. The base line of the non-mesophase peak can
be
approximated by drawing a base line connecting the base of each side of the
peak and demark it
from the mesophase peak. These non-mesophase peaks in the total carbon region
and the silicon peak are highlighted using the Peak Paint feature in the JADE
software and their area calculated. The non-mesophase peaks are not typically
significant relative to the area of the mesophase peak. The two areas for the
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mesophase peak and the silicon peak can then be used to calculate the
proportional
mesophase weight fraction in the sample by use of Formula (1):
Xm = Xs t (Am/Ast) (1)
where Xm is the proportional mesophase weight fraction in a sample, Xs, is the
weight
fraction of standard added to the sample such as silicon, Am is the mesophase
peak area and
A5, is the peak area of the standard. The term "proportional mesophase weight
fraction" is
used because a correction factor accounting for the relationship between the
standard and the
mesophase peaks may be useful in Formula (1), but we do not expect the
correction factor to
significantly change the result in Formula (1). The mesophase yield fraction
which is the
mesophase produced per hydrocarbon fed to the SHC reactor by weight should be
calculated
to determine whether the mesophase produced in the reaction is too high
thereby indicating
the risk of too much coke production. The yield fraction of TIOR produced in a
reaction per
hydrocarbon feed by weight is calculated by Formula (2):
YTIOR = MTIOR/MHCBN (2)
where YTIOR is the yield fraction of TIOR in the product; MTioR is the yield
mass of TIOR in
the product and MHcBN is the mass of hydrocarbon in the feed. Masses can be
used in the
calculation as mass flow rates in a continuous reaction or static masses in a
batch reaction.
The mesophase yield fraction is calculated by Formula (3):
Ymesophase = Xm * YTIOR (3)
where Y
- mesophase is the mesophase yield fraction. These formulas enable calculation
of the
yield fraction of TIOR, YTIOR, which is mass of TIOR produced per mass of
hydrocarbon fed
to the SHC reactor which can be multiplied by the fraction of mesophase in the
TIOR sample,
Xm, to determine the yield fraction of mesophase, Y
- mesophase, which is mass of mesophase
produced per mass of hydrocarbon fed to the SHC reactor. If the yield fraction
of mesophase
exceeds 0.5 wt-%, the severity of an SHC reactor should be reduced to avoid
excessive
coking in the reactor because mesophase production is substantial. In other
embodiments,
severity should be moderated should the yield fraction of mesophase exceed as
little as 0.3
and as high as 0.8 wt-%.
[0045] The amount of mesophase determined by the optical PLM method of
ASTM D
4616-95 is a method that samples a two dimensional area which is a volume
fraction. The
XRD method samples a three dimensional volume and should give a more accurate
indication
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of mesophase in terms of weight fraction relative to feed. It would not be
expected for the
two methods to give the identical result, but they should correlate.
EXAMPLE 1
[0046] A feed suitable for SHC is characterized in Table I. Unless
otherwise indicated,
this feed was used in all the Examples.
TABLE I
Vacuum Bottoms
Test
(975 F+)
Specific Gravity, g/cc 1.03750
API gravity -0.7
ICP Metals
Ni, wt. ppm 143
V, wt. ppm 383
Fe, wt. ppm 68.8
Microcarbon residue, wt-% 25.5
C, wt-% 80.3
H, wt-% 9.0
N, wt-% 0.4
Total N, wt. ppm 5744
Oxygen, wt-% in organics 0.78
Sulfur, wt-% 7
Ash, wt-% 0.105
Heptane insolubles, wt-% 16.1
Pentane insolubles, wt-% 24.9
Total chloride, mass ppm 124
Saybolt viscosity, Cst 150 C 1400
Saybolt viscosity, Cst 177 C 410
[0047] "ICP" stands for Inductively Coupled Plasma Atomic Emissions
Spectroscopy,
which is a method for determining metals content.
EXAMPLE 2
[0048] A TIOR sample from an SHC reaction using heavy oil feed from Example
1 and
0.7 wt-% iron content on iron sulfate monohydrate catalyst as a percentage of
non-gaseous
materials in the SHC reactor was analyzed for mesophase using an XRD method. A
sample
of SHC product material was blended with toluene, centrifuged and the liquid
phase
decanted. These steps were repeated on the remaining solids. The solids
remaining were then
dried in a vacuum oven at 90 C for 2 hours. Silicon standard was added to
the sample to give
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a concentration of 5.3 wt-% by adding silicon solid and acetone solvent to a
sample of TIOR
and slurried together with a mortar and pestle. The acetone evaporated out of
the slurry to
leave a solid comprising TIOR blended with silicon standard. An approximately
1 gram
sample of the solid sample with blended standard was spread onto a XRD sample
holder and
placed into the XRD instrument and scanned using parameters of
2.0/70.0/0.04/10(sec). The
XRD instrument was a Scintag X1 instrument which is a fixed slit system
equipped with a
theta-theta goniometer, a Peltier-cooled detector and a copper tube. The XRD
instrument was
run at settings of 45 kV and 35 mA. The resulting data was plotted using JADE
software
which was loaded on the XRD instrument.
[00491 FIGS. 2 and 3 show an XRD plot of the resulting TIOR sample. A peak
with a
centroid at 26.0 2-theta degrees represents the existence of mesophase. The
aggregate area of
the peaks in the total carbon region from 200 2-theta degrees to the right
most edge of a
silicon peak at 28.5 two theta degrees as shown shaded in FIG. 2 was
calculated to be
253,010 area counts using the Peak Paint function of JADE software. The right-
most edge of
the peak in the total carbon region was at 29.5 two theta degrees. The non-
mesophase peaks
in the total carbon region are identified and shaded along with the silicon
peak with a centroid
at 28.5 two theta degrees in FIG. 3 using the Peak Paint function. Bauxite,
for example,
typically includes titania which provides a peak at 26.2 two theta degrees.
Other non-
mesophase peaks are identified as such and highlighted in FIG. 3. The base
lines of the non-
mesophase peaks are shown in FIG. 3 with base lines connecting the base of
each side of the
respective peak to demark it from the rest of the mesophase peak. These non-
mesophase
peaks in the total carbon region and the silicon peak are highlighted using
the Peak Paint
feature in the JADE software to calculate their area. The area of the silicon
peak is 43,190
area counts, and the area other non-mesophase peaks in the total carbon region
is 1,374 area
counts which is relatively insignificant. The aggregate area of the peaks not
associated with
mesophase in the hydrocarbon range was calculated using Peak Paint to be
44,564 area
counts. The non-mesophase area was subtracted from the aggregate area of the
peaks in the
total carbon region peak to provide an area of the mesophase peak of 208,446
area counts.
The two areas for the mesophase peak and the silicon peak were then used to
calculate the
percent mesophase by Formula (1):
Xin = 0.053 * (208446/43190) = 0.2558 (1).
To determine the yield fraction of TIOR, Formula (2) is used for which:
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YTIOR = MTIOR/MHCBN = 18.85 g TIORJ342 g HCBN = 0.0551 (2).
Accordingly, Formula (3) is used to determine the yield fraction of mesophase:
Ymesophase = Xm * YTIOR7--. 0.249 * 0.0551 = 0.0141 (3).
The Y
- mesophase expressed as a percentage of 1.41 wt-% correlates to the mesophase
concentration of 1.22% deteimined by PLM using ASTM D 4616-95. Since the
mesophase
yield fraction is substantial in that it is above 0.5 wt-% the reaction was in
danger of
excessive coking which should prompt moderating its severity.
EXAMPLE 3
[0050] In this example, we examined the ability of iron in iron sulfate
monohydrate to
convert to the active iron sulfide. Iron sulfate monohydrate was mixed with
vacuum resid of
Example 1 at 450 C and 2000 psi (137.9 bar) in an amount such that 2 wt-% iron
was present
relative to the non-gaseous materials in the reactor. The temperature was
chosen because it is
the optimal temperature for pitch conversion for sulfur monohydrate catalyst.
The semi-
continuous reaction was set up so that hydrocarbon liquid and catalyst
remained in the
reactor; whereas, 6.5 standard liters/minute (slim) of hydrogen were fed
through the reaction
slurry and vented from the reactor. X-ray diffraction (XRD) characterization
of solid material
separated from vacuum resid feed during different stages of the reaction shows
that the
transformation of Fe(SO4)+120 to FeS is comparatively slow. FIG. 4 shows XRD
patterns
from samples taken from the semi-continuous reaction at various time
intervals. FIG. 4 shows
intensity versus two theta degrees for four XRD patterns taken at 0, 15, 30,
60 and 80 minutes
going from highest to lowest patterns in FIG. 4. Time measurement began after
the reactor
was heated for 30 minutes to reaction conditions. The presence of Fe(SO4)+170
is indicated
in the XRD pattern by a peak at 18.3 and 25.9 two theta degrees. Table II
below gives the
proportion of Fe(SO4).1420 at time. After reactor heat up at 0 minutes, only
30 wt-% of the Fe
is present as iron sulfide shown by a peak at 44 two theta degrees. Only after
80 minutes is
most of the Fe(SO4).1120 converted to FeS.
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TABLE II
Reaction Time (minutes) Fe(SO4).H70 (wt-%)
0 70
15 16
30 14
60 5
80 4
EXAMPLE 4
[0051] In order to understand the formation of iron sulfide from
bauxite an experiment
was performed by charging vacuum resid of Example 1 to the semi-continuous
reactor at
460 C, 2000 psi (137.9 bar), and feeding hydrogen through the resid at 6.5
slim. The bauxite
catalyst was present in an amount such that 0.7 wt-% iron was in the reactor
relative to the
hydrocarbon liquid and catalyst. The reaction was run for 80 minutes after the
reactor was
preliminarily heated for 30 minutes. XRD patterns were taken of solids
collected from the
reaction at 0, 15 and 80 minutes after preliminary heat up. A second set of
experiments were
performed with the same reaction conditions, except the reactor temperature
was set at 410 C
and solids were collected at 0 and 80 minutes after preliminary heat up. The
XRD patterns
are shown in FIG. 5. The experiments conducted at 460 C are the lowest three
XRD patterns
in FIG. 5, and the experiments conducted at 410 C are the highest three XRD
patterns in FIG.
5. In all cases, iron sulfide had already formed by the time the reactor
reached both reaction
temperatures indicated by the peak at 11 two theta degrees. No evidence of
iron oxide is
present in any of the XRD patterns indicating that essentially all of the iron
oxide had
converted to iron sulfide.
EXAMPLE 5
[00521 Bauxite containing 17.7 wt-% Fe present as Fe103 and 32.9% wt-%
Al present as
boehmite alumina was compared with other bulk available, iron-containing
minerals such as
iron sulfate monohydrate and Yandi limonite ore from various sources. Particle
size
characterizations were determined using the wet method of ASTM U0P856-07. The
characterization data for all of the materials are shown in Table III.
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TABLE III
Iron Sulfate
Limonite
Sample Description Bauxite mono- Hematite
Fines
hydrate
Al, wt-% 32.9 <0.006 0.7
Fe, wt-% 17.7 29.1 67.8 52.4
Ti, wt-% 1.88 <0.003 0.029
LOI at 900 C, mass-% 7.6 54.6 0.8 17.1
lion Compound Fe203 Fe(SO4) Fe703 Fe0OH
Iron compound, wt-% 25.3 79.1 97.0 83.4
Si02 4.5
A1201 62.2 1.3
S 0.0 18.7 0.0
BET surface area, m2/g 159.0 5.0 94.0
LANG surface area, m2/g 276.0 162.0
pore volume, cc/g 0.2 0.0 0.1
pore diameter, A 53.0 104.0 41.0
Particle size
median diameter, 1.2 2.9 3.8 2.8
Mean diameter, 1.0 2.3 2.7 26.7
<10 0.5 1.1 1.3 0.3
<25 0.7 1.8 2.4 0.9
<50 1.2 2.9 3.8 2.8
<75 1.9 4.1 5.3 26.9
<90 2.8 5.5 6.9 91.1
[00531 In a typical experiment, 334 grams of vacuum resid of Example 1
was combined
in a 1 liter autoclave with one of the iron sources, adding the iron at
between 0.4 and 2 wt-%.
In the examples cited in Table IV, the autoclave was heated to 445 C for 80
minutes at 2000
psi (137.9 bar). Hydrogen was continuously added through a sparger and passed
through the
reactor at a rate of 6.5 standard liters per minute and removed through a back
pressure valve
to maintain pressure. The hydrogen stripped out the light products which were
condensed in
cooled knock-out trap pots. Some of the limonite catalysts were pretreated by
adding 1 or 2
wt-% sulfur relative to the feed and catalyst and heating the mixture to 320
or 350 C at 2000
psi (137.9 bar) over hydrogen for an hour to activate the catalyst before
heating the mixture
to reaction temperature.
[0054] In Table IV, "mesophase yield, XRD, wt-% indicates mesophase
identified by
XRD and is expressed relative to the total hydrocarbon feed. "Mesophase
optical" is a
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percentage of mesophase identified in a sample examined by polarized light
microscopy. All
of the yield numbers are calculated as a ratio to the feed.
- 20 -
TABLE IV
0
t..)
o
Sample Description Bauxite Iron sulfate
monohydrate Hematite Limonite 1-
522- 522- 522- 522- 522- 522- 522- 522- 522- 522- 522- 522- 522- 'a
Run 523-4
522-86 522-73 522-77
12 13 125 124 82 87 84 132
81 41 65 122 74 vi
_
_ cio
1% sulfur,
2% sulfur, 2% sulfur, 1-
Pretreatment no no no no No no no no no
no no no no no
350 C
320 C 350 C
-
Iron content, wt-% 0.4 0.5 0.7 0.7 1.0 1.5 2.0 0.7
0.7 1.0 1.5 2.0 0.7 0.7 1.0 0.7 2.0
- -
Temperature, C 445 445 445 445 445 445 445 450
445 445 445 445 445 445 445 445 445
Pitch conversion,
82.3 82.1 82.0 83.1 82.6 82.5 83.4 76.88 78.4 79.1 81.8 80.0 79.3 70.1 79.1
75.0 83.1
wt-%
0
H2S, CO & CO2 yield, wt-% 4.6 4.7 4.6 4.5 4.1 3.4 3.4
4.6 4.4 3.9 4.5 4.2 4.2 3.8 4.3 4.4 5.8
0
-
I\)
C1-C4 yield, wt- /0 9.8 9.8 9.3 9.2 9.2 8.8 7.5
11.6 10.9 9.9 11.3 9.7 10.4 11.4 9.7 10.3 10.5
-.1
IV
-.1
Naphtha (C5-204 C) yield, wt-
H0,
24.9 21.0 22.9 22.5 20.8 19.2 19.8 21.1 24.9 22.7 22.3 20.4 25.1 1.5 22.6
1.2 21.5
%
I\)
0
LVGO (204 C-343 C) yield, wt-
H
24.9 25.0 24.9 24.6 27.4 25.2 29.6 25.8 22.8 24.9 23.9 27.3 21.2 30.0 24.0
29.5 27.5 0
%
I
H
- -
I\)
1
HVGO (343 C-524 C) yield,
21.7 21.6 21.8 21.9 22.2 24.4 22.4 13.1 15.2 17.1 15.5 15.3 16.3 30.1 17.8
32.3 20.4 0
wt-%
-.1
Pitch (524 C+) yield, wt-% 16.0 16.2 16.1 15.1 15.5 15.8
15.0 20.6 19.3 19.0 16.5 18.0 18.5 38.5 18.9
37.0 15.3
C5-524 C yield, wt-`)/0 71.4 67.5 69.6 69.0 70.4
68.8 71.8 60.0 62.9 64.8 61.7 63.1 62.6 54.9 64.4
61.1 69.4
TIOR yield, wt-% 3.0 2.5 2.3 , 2.3 2.9 2.6 1.9 7.1
_ 7.1 6.1 4.0 3.0 6.1 13.9 5.0 7.3 1.8 1-d
n
Mesophase yield, XRD, wt-% 0.22 0.15 0.03 0.07 0.00
0.00 0.00 1.03 0.75 0.43 0.37 0.22 0.89 0.00*
0.41 4.65 1.02
cp
Mesophase, Optical, % 0.11 0.28 0.00 0.07 0.00 0.00
0.00 1.70 0.94 0.50 0.39 1.77 0.12 4.53 6.13 1.35
3.72 c,
yD
'a
* This number is not trusted. It is believed that the excessive TIOR shielded
the mesophase from diffraction.
--.1
--.1
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[0055] The iron oxide and alumina catalyst demonstrated higher
conversion of pitch,
higher C5-524 C yield and lower TIOR than comparative catalysts at similar
iron contents.
Only after extensive pretreatment and high 2 wt-% iron loading did limonite
come close to
rivaling 2 wt-% iron from bauxite after no pretreatment. The pretreated
limonite was
marginally better only in TIOR yield, but had unacceptably high mesophase
yield. The
bauxite example shows higher pitch conversion, C5-524 C yield and lower TIOR
yield at 0.7
wt-% Fe than the comparative materials. The bauxite also out performs hematite
which is 97
wt-% Fe203 suggesting that the alumina in bauxite provides a performance
benefit.
Conversion data from these experiments suggest that the slow formation of iron
sulfide in
iron sulfate monohydrate and limonite might impede conversion and undesirably
increase the
TIOR yield.
[0056] In many cases in Table IV, the amount of mesophase determined by
the optical
method of ASTM D 4616-95 correlates well to the amount of mesophase determined
by
XRD.
EXAMPLE 6
[0057] Catalysts from the series of experiments used to generate data
reported in
Example 5 in which 0.7 wt-% iron relative to the weight of liquid and catalyst
in the SHC
reactor were recovered and examined by XRD spectroscopy and scanning electron
microscope (SEM).
[0058] FIG. 6 shows an XRD pattern for iron sulfate monohydrate catalyst
used in run
523-4 reported in Example 5. The XRD pattern in FIG. 6 shows a sharp peak at
43 two theta
degrees identified as iron sulfide indicating relatively large crystallite
material. The broad
peak at 26 two theta degrees is identified as mesophase. A micrograph of the
iron sulfide
crystallites formed from iron sulfate monohydrate precursor crystallites from
run 523-4 in
FIG. 7 by SEM at 10,000 times indicates a variety of crystallite sizes ranging
typically from
150 to 800 nm. The iron sulfide crystallites are the black particles in FIG.
7.
[0059] FIG. 8 shows an XRD pattern for the TIOR produced with limonite
catalyst used
in tun 522-73 reported in Example 5. The XRD pattern in FIG. 8 also shows a
sharp peak at
43 two theta degrees identified as iron sulfide indicating relatively large
crystallite material.
Again, a large, broad peak at 26 two theta degrees is identified as mesophase.
A micrograph
of the iron sulfide crystallites formed from limonite precursor crystallites
from run 522-73 in
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FIG. 9 by SEM at 50,000 times indicates a variety of crystallite sizes ranging
typically from
50 to 800 nm. The iron sulfide crystallites are the black particles in FIG. 9.
[0060] FIG. 10 shows an XRD pattern for bauxite catalyst from run 522-
125 reported in
Example 5. The XRD pattern shows a broad, squat peak at 43 two theta degrees
identified as
iron sulfide. This broad peak shape is indicative of nano-crystalline
material. No peak at 26
two theta degrees can be identified as mesophase. The peak at 25.5 two theta
degrees is likely
titania present in the bauxite and/or silver which is suspected to be a
contaminant from a
gasket on the equipment. The peak at 26.5 two theta degrees is also likely a
silver chloride
contaminant. The peak at 28 two theta degrees is boehmite in the catalyst.
Because bauxite
also contains a considerable amount of boehmite alumina in addition to iron,
the crystallite
size of the iron sulfide was indeterminate from the SEM.
[0061] A micrograph of bauxite catalyst used in the run 522-82
reported in Example 5 is
shown in FIG. 11. The micrograph in FIG. 11 was made by scanning transmission
electron
microscopy (STEM) compositional x-ray mapping. The micrograph indicates that
the
boehmite particles range in size from 70 to 300 nm while the iron sulfide
crystallites range
uniformly at 25 urn between 15 and 40 nm. The iron sulfide crystallites are
the darker
materials in FIG. 11 and several are encircled as examples. Many of the iron
sulfide
crystallites are identified as single crystallites in FIG. 11. The alumina
particles are the
larger, lighter gray materials in FIG. 11. The dark black material in the top
center of FIG. 11
is believed to be an impurity.
[0062] Little or no mesophase was indicated for the iron oxide and
alumina catalyst by
XRD while the other catalysts formed significant amounts of mesophase when 0.7
wt-% iron
content was present in the SHC reaction zone.
EXAMPLE 7
[0063] TIOR from the series of experiments used to generate the data in
Example 5 in
which 0.7 wt-% iron relative to the weight of liquid and catalyst in the SHC
reactor were
recovered and examined by polarized light microscopy (PLM) using ASTM D 4616-
95 to
confirm the indications of mesophase in Examples 5 and 6.
[0064] FIG. 12 is a PLM photograph of TIOR produced from run 523-4
with iron sulfate
monohydrate catalyst reported in Example 5 and for which catalyst an XRD
pattern is given
in FIG. 6 and a SEM micrograph is given in FIG. 7 in Example 6. The photograph
in FIG. 12
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shows a significant amount of material coalesced together indicating
mesophase. The PLM
photograph in FIG. 12 supports results from XRD analysis that mesophase was
present by the
existence of the peak at 26 two theta degrees and the amount of optical
mesophase calculated
by ASTM D 4616-95 of 1.7% and by XRD of 1.03 wt-%.
[0065] FIG. 13 is a PLM photograph of TIOR from run 522-73 with limonite
catalyst
reported in Example 5 and for which an XRD pattern is given in FIG. 8 and a
SEM
micrograph is shown in FIG. 9. The photograph in FIG. 13 shows less material
coalesced
together than in FIG. 12, but the bubble-like formations indicate mesophase.
The PLM
photograph in FIG. 13 supports results from XRD analysis that mesophase was
present by the
existence of the peak at 26 two theta degrees in FIG. 8 and the amount of
optical mesophase
calculated by ASTM D 4616-95 of 4.65 % and by XRD of 1.35 wt-%.
[0066] FIG. 14 is a PLM photograph of TIOR from run 522-125 produced
with bauxite
catalyst reported in Example 5 and for which an XRD pattern is given in FIG.
11. The
micrograph in FIG. 14 shows much less coalescing material than in FIGS. 12 and
13. Only
trace amounts of mesophase are present in the PLM micrograph supporting
results from XRD
analysis that substantially no mesophase was present by the existence of the
peak at 26 two
theta degrees and the amount of mesophase calculated by ASTM D 4616-95 of 0.00
and by
XRD of 0.03 wt-%.
EXAMPLE 8
[0067] A bauxite catalyst containing alumina and iron oxide used in run 522-
124 reported
in Example 5 was compared to iron oxide without alumina, iron oxide with
boehmite
alumina, iron sulfate, limonite and iron sulfate with boehmite alumina using
the feed of
Example 1. Reaction conditions included a semi-continuous reactor at 445 C,
pressure of
2000 psi (137.9 bar), a residence time of 80 minutes and iron on catalyst in
the reaction zone
per hydrocarbon and catalyst of 0.7 wt-%. Results are shown in Table IV.
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TABLE V
Fe,03 +
Fe(SO4)+
Catalyst Bauxite Fe203Fe(SO4)
Boehmite
Boehmite
Run 522-124 522-116 522-109 522-114
522-111
Aluminum content, wt% 0 1.2 0 1.2
Conversion, wt-% 83.1 81.1 79.9 78.1 81.2
C5 to 525 C yield,
69.0 67.3 62.6 63.1 65.2
wt-%
TIOR yield, wt-% 2.3 4.9 5.1 7.2 3.7
Mesophase yield, XRD,
0.07 0.60 0.35 0.95 0.36
wt-%
[0068]
In each case and for all parameters, addition of the alumina reduces mesophase
generation of the iron containing catalyst. Addition of boehmite alumina
improves the
performance of iron sulfate in all categories, but does not appear to help
iron oxide except in
mesophase reduction. Bauxite has the best performance in each category.
EXAMPLE 9
[0069] The iron oxide and alumina catalyst of the present invention was
also tested for
the ability to increase the flowability of heavy hydrocarbon as measured by
API index. Heavy
vacuum bottoms feed of Example 1 having an API index of -0.7 degrees was fed
to the
reactor described in Example 4 under similar conditions without any
pretreatment of the
catalyst. The catalyst comprised 3.7 wt-% of the non-gaseous material in the
reactor. Iron
comprised 17.7 wt-% of the catalyst, so that 0.7 wt-% of the hydrocarbon and
catalyst in the
reactor comprised iron. The mean particle diameter of the bauxite was between
1 and 5
microns with a BET surface area of 159 m2/g. Differing conditions and results
are provided
in Table VI.
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TABLE VI
Example 1 2
Pressure 2000 1500
Temperature, 'V 455 460
Reaction time, minutes 80 80
Liquid selectivity, wt-% 81.9 81.0
Coke yield, wt-% of feed 1.7 0.6
Gas selectivity, wt-% 16.4 18.9
API of Liquid Product 24.0 23.8
%Increase in API 2470 2450
[0070] Table VI shows that the iron and alumina containing catalyst
provides an uplift in
flowability in terms of API gravity of 24 times.
EXAMPLE 10
[00711 The alumina and iron containing catalysts were tested with varying
water contents
to determine the effect of water on performance on the same bauxite catalyst.
The conditions
of 455 C, 2000 psi (137.9 bar), a semi-continuous reactor with 6.5 sl/min of
hydrogen and
residence time of 80 minutes were constant for all the experiments. Iron
content of catalyst
per non-gas material in the SHC reactor was also constant at 0.7 wt-%. The
bauxite catalyst
tested comprised 39.3 wt-% alumina, 15.4 wt-% iron oxide and a loss on
ignition (LOI) at
900 C of 38.4 wt-% which predominantly represents water, had a BET surface
area of 235
m2/g and a mean particle diameter of 299 microns. Water content on catalyst
indicated by
loss on ignition (LOI) at 900 C was varied as shown in Table V by drying.
Throughout the
experiments, the catalyst comprised 63.8 wt-% alumina and 25.0 wt-% iron oxide
on a non-
volatile basis.
TABLE VII
Sample 523-87 523-93 523-94
LOI, wt-% 38.4 23.3 10.6
Pitch conversion, wt-% 84.42 84.31 84.25
C1-C4 yield, wt-% feed 10.78 10.56 10.63
C5 to 525 C yield, wt-% feed 67.70 67.07 68.80
TIOR yield, wt-% 3.19 3.33 3.16
Mesophase yield, XRD, wt-% 0.18 0.18 0.18
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[0072] Performance of the alumina and iron oxide catalyst is comparable
at all water
contents. This performance indicates that water content does not impede the
formation of iron
sulfide from iron oxide.
EXAMPLE 11
[0073] The alumina and iron containing catalysts were tested at varying
larger particle
diameters to assess the effect on performance for similar bauxite catalyst.
The conditions of
455 C, 2000 psi (137.9 bar), a semi-continuous reactor with 6.5 sUmin of
hydrogen and
residence time of 80 minutes were constant for all the experiments. Iron
content of catalyst in
the SHC reactor was also constant at 0.7 wt-%. The mean particle diameter was
determined
using dry and wet methods with ASTM U0P856-07 by light scattering with a
Microtrac S
3500 instrument. In the wet method, the weighed sample is slurried in a known
amount of
water and sonicated. An aliquot is put in the sample chamber for the light
scattering
measurement. In the dry method, a different sample holder is used and the
particles are
measured directly but also by light scattering. We believe the dry method
gives diameters
that more closely replicate the character of the catalyst that initially
encounters the
hydrocarbon feed. Mean particle diameter and performance comparisons are
presented in
Table VIII.
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TABLE VIII
Sample 523-77 523-83 523-84 523-88 523-89 523-87 523-90 523-100
. -
Dry mean particle
4.9 4.9 4.9 249 258 299 481
554
diameter, microns
Dry median
particle diameter, 3.2 3.2 3.2 276 283 327 365
354
microns
Wet mean particle
1.0 1.0 1.0 3.3 3.2 4.2 3.5
4.2
diameter, microns
Wet median
particle diameter, 1.2 1.2 1.2 2.6 2.7 2.9 2.7
3.3
microns
A1/03, wt-% 62.2 62.2 62.2 40.2 39.3 39.3 39.5
38.4
Fe203, wt-% 25.3 25.3 25.3 15.9 16.0 15.4 16.0
16.6
BET surface area,
159 159 159 246 237 235 237
235
tog
LOT 7.6 7.6 7.6 37.5 36.9 38.4 36.1
38.3
Pitch conversion,
84.6 84.2 85.1 83.7 82.9 84.4 84.8
86.6
wt-%
H2S, CO & CO2
4.2 4.4 4.3 4.2 4.2 4.2 4.3
3.1
yield, wt-%
Ci-C4yield, wt-% 10.4 10.9 10.6 10.6 10.5 10.8 10.9
7.9
Naphtha (C5-
204 C) yield, 27.2 27.3 28.2 26.9 24.9 26.6 26.1
26.6
wt-%
LVGO (204 C-
343 C) yield, 24.8 24.3 24.4 25.2 24.1 24.5 25.2
26.1
wt-%
HVGO (343 C-
524 C) yield, 17.7 16.6 17.0 15.2 16.3 16.5 17.2
17.9
wt-%
Pitch (524 C+)
13.9 14.1 13.5 14.5 15.2 13.9 13.6
11.9
yield, wt-%
C5-524 C yield,
70.0 68.3 69.9 67.3 65.4 67.6 68.5
70.6
wt-%
TIOR yield, wt-% 3.7 3.9 3.1 2.7 4.0 3.2 2.7
2.9
Mesophase yield,
0.12 0.14 0.18 0.06 0.06 0.18 0.07
0.09
XRD, wt-%
[0074] The alumina and iron oxide catalysts with mean particle diameters
over 200
microns perfoun as well as the catalyst with mean particle diameters below 5
microns.
Comparable performance was observed at mean particle diameters as high as 554
microns.
We do not believe that water content affected performance comparisons because
of our
findings that water content does not substantially affect performance. Wet
method particle
determinations were dramatically smaller which may indicate that the method
breaks the
catalyst particles down to finer particles. This phenomenon may occur in the
SHC reactor.
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EXAMPLE 12
[0075] Samples of bauxite with different particles sizes from Examples
10 and 11 were
subjected to SHC at the same conditions as in Example 5 except at reactor
temperatures of
455 C. The reactor temperature was 445 C for iron sulfate. XRD was used to
deteimine
iron sulfide crystallite mean diameter based on the width of the iron sulfide
peaks at 43 two
theta degrees. Crystallite size was determined using the Debye-Scherrer
formula for size
broadening of diffraction peaks. Crystallite size and mesophase yield fraction
are shown in
Table IX.
TABLE IX
523- 523- 523- 523- 523- 523- 523-
523-
Sample 104
77 83 88 100 89 87 93
(FeSO4)
FeS crystallite mean
11.5 11.5 12 12 11.5 9 26
diameter, nm
Mesophase yield
0.12 0.14 0.06 0.09 0.06 0.18 0.18 0.79
fraction, XRD, wt-%
10 [0076] The iron sulfide mean crystallite diameters from XRD for
bauxite reside in a
narrow nanometer range much lower than the smallest iron sulfide mean
crystallite diameter
for iron sulfate. After recycling the catalyst samples to the SHC once and
twice, the iron
sulfide crystallite sizes did not change substantially.
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