U.S. patent application number 16/115775 was filed with the patent office on 2019-03-14 for hydroprocessing of high density cracked fractions.
The applicant listed for this patent is ExxonMobil Research and Engineering Company. Invention is credited to Ajit B. Dandekar, Mark A. Deimund, Samia Ilias, Darryl D. Lacy, Randolph J. Smiley, Scott J. Weigel.
Application Number | 20190078027 16/115775 |
Document ID | / |
Family ID | 63684442 |
Filed Date | 2019-03-14 |
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United States Patent
Application |
20190078027 |
Kind Code |
A1 |
Deimund; Mark A. ; et
al. |
March 14, 2019 |
HYDROPROCESSING OF HIGH DENSITY CRACKED FRACTIONS
Abstract
Systems and methods are provided for upgrading a heavy cracked
feedstock in a single reaction stage under fixed bed
hydroprocessing conditions, including exposing the feedstock to a
first bulk or supported mixed metal catalyst comprising Ni and Mo;
exposing the feedstock to a second bulk or supported mixed metal
catalyst comprising Ni and W; and exposing the feedstock to a third
catalyst comprising a zeolite-based hydrocracking catalyst.
Inventors: |
Deimund; Mark A.; (Jersey
City, NJ) ; Ilias; Samia; (Bridgewater, NJ) ;
Smiley; Randolph J.; (Hellertown, PA) ; Dandekar;
Ajit B.; (The Woodlands, TX) ; Weigel; Scott J.;
(Allentown, PA) ; Lacy; Darryl D.; (Easton,
PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ExxonMobil Research and Engineering Company |
Annandale |
NJ |
US |
|
|
Family ID: |
63684442 |
Appl. No.: |
16/115775 |
Filed: |
August 29, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62555748 |
Sep 8, 2017 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10G 45/50 20130101;
C10G 45/52 20130101; C10G 47/02 20130101; C10G 65/12 20130101; C10G
2300/301 20130101; C10G 47/16 20130101; C10G 47/18 20130101; C10G
45/08 20130101; C10G 2300/308 20130101 |
International
Class: |
C10G 45/08 20060101
C10G045/08; C10G 45/52 20060101 C10G045/52; C10G 47/18 20060101
C10G047/18 |
Claims
1. A process for upgrading a heavy cracked feedstock, comprising:
providing a feedstock comprising a density at 15.degree. C. of 1.06
g/cm.sup.3 or more, at least 50 wt % of one or more 343.degree. C.+
cracked fractions, and a sulfur content of 0.8 to 5.0 wt % sulfur;
in a single reaction stage under fixed bed hydroprocessing
conditions, exposing the feedstock to a first bulk or supported
mixed metal catalyst comprising Ni and Mo; exposing the feedstock
to a second bulk or supported mixed metal catalyst comprising Ni
and W; and exposing the feedstock to a third catalyst comprising a
zeolite-based hydrocracking catalyst.
2. The process of claim 1, wherein the zeolite-based hydrocracking
catalyst comprises a Group VIII noble metal.
3. The process of claim 2, wherein the zeolite-based hydrocracking
catalyst comprises 0.5 to 2.5 wt % Pt.
4. The process of claim 1, wherein the third catalyst further
comprises an aromatic saturation catalyst comprising Pd, Pt, or a
combination thereof on an aluminosilicate support.
5. The process of claim 4, wherein the aromatic saturation catalyst
comprises Pd and Pt in a wt % ratio of about 3:1 Pd to Pt.
6. The process of claim 4, wherein the aromatic saturation catalyst
comprises 2.0 wt % Pt.
7. The process of claim 1, wherein the zeolite exhibits a faujasite
(FAU) framework type.
8. The process of claim 1, wherein the feedstock comprises a
density at 15.degree. C. of 1.1 g/cm.sup.3 or more, a T.sub.10 of
at least 343.degree. C. and a T.sub.90 of at least 475.degree. C.;
and a sulfur content of 3.0 wt % to 5.0 wt %.
9. The process of claim 8, wherein the feedstock comprises a
de-asphalted heavy cracked feedstock.
10. The process of claim 1, wherein the fixed bed hydroprocessing
conditions include a temperature of 300.degree. C. to 400.degree.
C., a pressure of 1500 psig to 3000 psig, a hydrogen treat gas rate
of 2,000 scf/bbl to 12,000 scf/bbl, and a LHSV of 0.2 h.sup.-1 to
1.5 h.sup.-1.
11. A system for processing a cracked feedstock comprising: a
hydroprocessing reactor comprising a hydroprocessing inlet, and a
hydroprocessing outlet, and a fixed bed comprising a first bulk or
supported mixed metal catalyst comprising Ni and Mo; a second bulk
or supported mixed metal catalyst comprising Ni and W; and a third
catalyst comprising a zeolite-based hydrocracking catalyst; wherein
the hydroprocessing inlet is designed to receive a feedstock
comprising a density at 15.degree. C. of 1.06 g/cm.sup.3 or more,
at least 50 wt % of one or more 343.degree. C.+ cracked fractions,
and a sulfur content of 1.0 to 5.0 wt % sulfur; and wherein the
fixed bed is oriented such that the feedstock contacts the first
catalyst, second catalyst, and third catalyst sequentially.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application Ser. No. 62/555,748 filed Sep. 8, 2017, which is herein
incorporated by reference in its entirety.
FIELD
[0002] Systems and methods are provided for hydroprocessing of
heavy cracked petroleum fractions to form low sulfur hydroprocessed
product fractions.
BACKGROUND
[0003] High density cracked fractions are particularly challenging
in refining operations. For example, the main column bottoms (MCB,
also called catalytic slurry oil or cat tar) of an FCC unit
requires significant treatment to convert it to useful products.
One product, heavy aromatic fuel oil (HAFO), is mainly MCB,
combined with minor amounts of steam cracker tar and coal tar. All
three of these components are highly aromatic (65 to 85% of the
carbon atoms in these streams are aromatic). Further, MCB has high
sulfur content (.about.3 wt %), making such processing challenging.
At present, disposal of MCB is feasible as HAFO, but future
regulations on sulfur content could make this disposal method
infeasible.
[0004] It is desirable to remove sulfur from fuel oil to levels of
0.5 wt % or lower. Thus, there is an incentive to process
high-sulfur fuel oil streams (such as MCB) into low sulfur fuel
products such as low sulfur fuel oil (LSFO), gasoline, and
ultra-low sulfur diesel (ULSD) via hydrotreating or other
chemistries. MCB is, however, prone to hydrotreating reactor
fouling caused by feed incompatibility. When MCB is blended with
virgin crude oil streams, fouling occurs in the hydrotreater, and
it ages rapidly and/or plugs the reactor. Thus, separate
hydrotreating and other means of upgrading the MCB feed are
required to allow for conversion to more useful low sulfur
products, as well as to ensure compatibility of blending with other
refinery streams.
[0005] It has been discovered that a sequential combination of
chemistries can be effective in upgrading this MCB stream into ULSD
and LSFO, with minimal naphtha and gas make. This combination of
hydrotreating, followed by a hydrocracking catalyst, mixed
hydrocracking-arosat catalyst, mixed noble-metal catalyst, or
mixtures thereof, has proven effective at converting much of the
700.degree. F.+ material in MCB into ULSD blendstock-range
molecules while also greatly reducing API gravity and sulfur and
nitrogen content of the stream.
[0006] At present, disposal of MCB is feasible as HAFO, but future
regulations on sulfur content could make this disposal method
infeasible. Accordingly, hydrotreating and hydrocracking and/or
saturating aromatics in the stream to upgrade the material to ULSD
blendstock or other useful fuel streams would be quite valuable and
preferable. There is a need to dispose of MCB (namely 700.degree.
F.+ components), as it can be no longer used as-is for HAFO.
Simultaneously reducing the sulfur content and boiling point range
can allow for formation of clean fuel streams.
SUMMARY
[0007] In various aspects, systems and methods are provided for
upgrading a heavy cracked feedstock. Although most references
within this application will be to processes for simplicity, it
would be well understood to a person of skill in the art where
similar attributes would be equally applicable to systems. The
process comprises providing a feedstock comprising a density at
15.degree. C. of 1.06 g/cm.sup.3 or more, at least 50 wt % of one
or more 343.degree. C.+ cracked fractions, and a sulfur content of
0.8 to 5.0 wt % sulfur, and, in a single reaction stage under fixed
bed hydroprocessing conditions, exposing the feedstock to a first
bulk or supported mixed metal catalyst comprising Ni and Mo;
exposing the feedstock to a second bulk or supported mixed metal
catalyst comprising Ni and W; and exposing the feedstock to a third
catalyst comprising a zeolite-based hydrocracking catalyst.
[0008] In certain aspects, the zeolite-based hydrocracking catalyst
comprises a Group VIII noble metal such as Pt. The Pt will
typically comprises 0.5 to 2.5 wt % of the hydrocracking catalyst.
In other aspects, the zeolite exhibits a faujasite (FAU) framework
type.
[0009] Additionally or alternatively, the third catalyst may
comprise an aromatic saturation catalyst on an aluminosilicate
support. The arosat catalyst may include Pd, Pt, or a combination
thereof. When the arosat catalyst comprises both Pd and Pt, it
would typically do so in a wt % ration of about 3:1 Pd to Pt.
[0010] In yet another aspect, the feedstock is a deasphalted heavy
cracked feed. Additionally or alternatively, the fixed bed
hydroprocessing conditions include a temperature of 300.degree. C.
to 400.degree. C., a pressure of 1500 psig to 3000 psig, a hydrogen
treat gas rate of 2,000 scf/bbl to 12,000 scf/bbl, and a LHSV of
0.2 h.sup.-1 to 1.5 h.sup.-1.
[0011] Also provided is a system for processing a cracked feedstock
comprising: a hydroprocessing reactor comprising a hydroprocessing
inlet, and a hydroprocessing outlet, and a fixed bed comprising a
first bulk or supported mixed metal catalyst comprising Ni and Mo;
a second bulk or supported mixed metal catalyst comprising Ni and
W; and a third catalyst comprising a zeolite-based hydrocracking
catalyst; wherein the hydroprocessing inlet is designed to receive
a feedstock comprising a density at 15.degree. C. of 1.06
g/cm.sup.3 or more, at least 50 wt % of one or more 343.degree. C.+
cracked fractions, and a sulfur content of 1.0 to 5.0 wt % sulfur;
and wherein the fixed bed is oriented such that the feedstock
contacts the first catalyst, second catalyst, and third catalyst
sequentially.
BRIEF DESCRIPTION OF THE FIGURES
[0012] FIG. 1 depicts catalyst bed configurations according the
present disclosure and those used in Examples 1 and 2.
[0013] FIGS. 2A-2F provide graphical data obtained in Example
1.
[0014] FIGS. 3A-3F provide graphical data obtained in Example
2.
[0015] FIG. 4 depicts catalyst bed configurations according the
present disclosure and those used in Example 3.
[0016] FIGS. 5A-5F provide graphical data obtained in Example
3.
[0017] FIG. 6 depicts catalyst bed configurations according the
present disclosure and those used in Examples 4 and 5.
[0018] FIGS. 7A-7F provide graphical data obtained in Example
4.
[0019] FIGS. 8A-8F provide graphical data obtained in Example
5.
DETAILED DESCRIPTION
[0020] In various aspects, systems and methods are provided for
upgrading a high density cracked feedstock, such as a catalytic
slurry oil, by hydroprocessing. In this discussion, reference may
be made to catalytic slurry oil, FCC bottoms, and main column
bottoms. These terms can be used interchangeably herein.
Difficulties in processing heavy cracked feeds can be related to
difficulties in performing distillation on the feeds.
Conventionally, one of the strategies for processing a challenging
feedstock can be to use distillation to separate a more favorable
portion of a feed from a typically higher boiling less favorable
portion. Under such a conventional strategy, an atmospheric
distillation can be used to separate a feed into lower boiling
portions and a higher boiling portion at a distillation cut point
between about 600.degree. F. (.about.316.degree. C.) and about
700.degree. F. (.about.371.degree. C.). The higher boiling portion
can then correspond to a roughly 316.degree. C.+ portion, or a
roughly 343.degree. C.+ portion, or a roughly 371.degree. C.+
portion. Conventionally, a further distillation can be performed on
this higher boiling portion under reduced pressure or vacuum
distillation conditions. This can produce one or more vacuum
distillate fractions and a bottoms fraction. Unfortunately, heavy
cracked feeds such as catalytic slurry oils can often have a
density of about 1.04 g/cm.sup.3 or more, or about 1.06 g/cm.sup.3
or more, or about 1.08 g/cm.sup.3 or more, such as up to 1.14
g/cm.sup.3 or possibly still higher. At such higher density values,
performing a vacuum distillation under conventional vacuum
distillation conditions becomes increasingly difficult and/or
inefficient. In particular, such high density fractions can tend to
have poor separation characteristics under conventional vacuum
distillation conditions. As a result, either substantial amounts of
undesirable components can remain in the "desired" distillate
fraction(s), and/or substantial amounts of the desired components
can remain in the bottoms fraction.
[0021] It has been unexpectedly discovered that heavy cracked
fractions, such as catalytic slurry oils, can be hydroprocessed
with reduced or minimized amounts of coking by exposing the
fraction, in sequence, to a first mixed metal catalyst comprising
Ni and Mo, a second mixed metal catalyst comprising Ni and W, and a
third catalyst comprising a zeolite-based hydrocracking catalyst in
a single reaction stage. In first and second catalysts may be bulk
metal or supported catalysts. As used herein, the term "single
reaction stage" means that no intermediate separation is performed
between exposing the feed to the catalysts. In other words, the
reactions described herein may take place in a single reactor or
multiple reactors. So long as no intermediate separation is
performed between exposures to the different catalysts, then it can
be said that the process takes place in a single reaction
stage.
[0022] This third zeolite-based hydrocracking catalyst can be any
number of commercially available hydrocracking catalysts.
Additionally or alternatively, the third catalyst can include an
aromatic saturation ("arosat") catalyst. Additionally or
alternatively, the third catalyst can include a noble metal. Use of
a zeolite-based hydrocracking catalyst with additional aromatic
saturation and/or noble metal catalyst would conventionally be
considered undesirable with feeds having high aromatic, nitrogen,
and sulfur content because of rapid poisoning of the catalyst.
Particularly, the organosulfur and organonitrogen species present
in the feed are thought to interact with noble metals and acid
sites on hydrocracking, arosat, and/or noble-metal catalysts,
respectively, causing this catalyst poisoning and deactivation. It
is conventionally believed widely in the industry that hydrogen
sulfide and ammonia are also involved. Thus, these types of
catalysts are generally not employed industrially in single-stage
and/or sour service operations (in the presence of high
concentrations of S- and N-containing species). In the present
disclosure, the initial hydrotreating catalysts are present to help
convert these feed organosulfur and organonitrogen species into
hydrogen sulfide and ammonia, respectively, before reaching the
third catalyst bed. Surprisingly, this also translates to less
deactivation and poisoning of the hydrocracking, arosat, and/or
noble-metal catalysts, enabling single-stage sour service operation
for catalysts in the third bed. It is believed here that the much
smaller hydrogen sulfide and ammonia molecules are less
preferentially adsorbed onto catalytic sites in the hydrocracking,
arosat, and/or noble-metal catalysts than the larger organosulfur
and organonitrogen species, and thus, they cause reduced catalytic
poisoning. This discovery enables cost and complexity savings due
to the lack of a requirement for separations of hydrogen sulfide
and ammonia from streams between catalyst beds, as well as any
additional feed treatments, in industrial processes. In this
application, the first hydrotreating catalyst bed (Ni and Mo, in
this instance) is intended to do hydrotreating on the "easier" S-
and N-containing species to reduce the organosulfur and
organonitrogen content dramatically from the levels found in the
feed. Use of a second intermediate bed of higher activity
hydrotreating catalyst (such as a Ni and W containing material) can
further reduce organic S- and N-content to ppm levels by converting
the more refractory molecules that are thought to act as stronger
catalyst poisons. At such low levels, the organosulfur and
organonitrogen species cause significantly less poisoning and
deactivation relative to their feed levels, and furthermore the
hydrogen sulfide and ammonia present surprisingly do not appear to
have any significant effect on catalyst activity in the third bed
containing hydrocracking, arosat, and/or noble-metal catalysts.
[0023] In some aspects, reference may be made to conversion of a
feedstock relative to a conversion temperature. Conversion relative
to a temperature can be defined based on the portion of the
feedstock that boils at greater than the conversion temperature.
The amount of conversion during a process (or optionally across
multiple processes) can correspond to the weight percentage of the
feedstock converted from boiling above the conversion temperature
to boiling below the conversion temperature. As an illustrative
hypothetical example, consider a feedstock that includes 40 wt % of
components that boil at 700.degree. F. (.about.371.degree. C.) or
greater. By definition, the remaining 60 wt % of the feedstock
boils at less than 700.degree. F. (.about.371.degree. C.). For such
a feedstock, the amount of conversion relative to a conversion
temperature of .about.371.degree. C. would be based only on the 40
wt % that initially boils at .about.371.degree. C. or greater. If
such a feedstock could be exposed to a process with 30% conversion
relative to a .about.371.degree. C. conversion temperature, the
resulting product would include 72 wt % of .about.371.degree. C.-
components and 28 wt % of .about.371.degree. C.+ components.
[0024] In various aspects, reference may be made to one or more
types of fractions generated during distillation of a feedstock or
effluent. Such fractions may include naphtha fractions, kerosene
fractions, diesel fractions, and other heavier (gas oil) fractions.
Each of these types of fractions can be defined based on a boiling
range, such as a boiling range that includes at least .about.90 wt
% of the fraction, or at least .about.95 wt % of the fraction. For
example, for many types of naphtha fractions, at least .about.90 wt
% of the fraction, or at least .about.95 wt %, can have a boiling
point in the range of .about.85.degree. F. (.about.29.degree. C.)
to .about.350.degree. F. (.about.177.degree. C.). For some heavier
naphtha fractions, at least .about.90 wt % of the fraction, and
preferably at least .about.95 wt %, can have a boiling point in the
range of .about.85.degree. F. (.about.29.degree. C.) to
.about.400.degree. F. (.about.204.degree. C.). For a kerosene
fraction, at least .about.90 wt % of the fraction, or at least
.about.95 wt %, can have a boiling point in the range of
.about.300.degree. F. (.about.149.degree. C.) to .about.600.degree.
F. (.about.288.degree. C.). For a kerosene fraction targeted for
some uses, such as jet fuel production, at least .about.90 wt % of
the fraction, or at least .about.95 wt %, can have a boiling point
in the range of .about.300.degree. F. (.about.149.degree. C.) to
.about.550.degree. F. (.about.288.degree. C.). For a diesel
fraction, at least .about.90 wt % of the fraction, and preferably
at least .about.95 wt %, can have a boiling point in the range of
.about.350.degree. F. (.about.177.degree. C.) to .about.700.degree.
F. (.about.371.degree. C.). For a (vacuum) gas oil fraction, at
least .about.90 wt % of the fraction, and preferably at least
.about.95 wt %, can have a boiling point in the range of
.about.650.degree. F. (.about.343.degree. C.) to
.about.1100.degree. F. (.about.593.degree. C.). Optionally, for
some gas oil fractions, a narrower boiling range may be desirable.
For such gas oil fractions, at least .about.90 wt % of the
fraction, or at least .about.95 wt %, can have a boiling point in
the range of .about.650.degree. F. (.about.343.degree. C.) to
.about.1000.degree. F. (.about.538.degree. C.), or
.about.650.degree. F. (.about.343.degree. C.) to .about.900.degree.
F. (.about.482.degree. C.). A residual fuel product can have a
boiling range that may vary and/or overlap with one or more of the
above boiling ranges. A residual marine fuel product can satisfy
the requirements specified in ISO 8217, Table 2.
[0025] In this discussion, a low sulfur fuel oil can correspond to
a fuel oil containing about 0.5 wt % or less of sulfur. An ultra
low sulfur fuel oil, which can also be referred to as an Emission
Control Area fuel, can correspond to a fuel oil containing about
0.1 wt % or less of sulfur. A low sulfur diesel can correspond to a
diesel fuel containing about 500 wppm or less of sulfur. An ultra
low sulfur diesel can correspond to a diesel fuel containing about
15 wppm or less of sulfur, or about 10 wppm or less.
[0026] It is noted that when initially formed, a catalytic slurry
oil can include several weight percent of catalyst fines. Any such
catalyst fines can be removed prior to incorporating a fraction
derived from a catalytic slurry oil into a product pool, such as a
naphtha fuel pool or a diesel fuel pool. In this discussion, unless
otherwise explicitly noted, references to a catalytic slurry oil
are defined to include catalytic slurry oil either prior to or
after such a process for reducing the content of catalyst fines
within the catalytic slurry oil.
Feedstocks for Hydroprocessing--Cracked Fractions
[0027] A catalytic slurry oil is an example of a suitable cracked
fraction for incorporation into a feedstock. It is conventionally
understood that conversion of .about.1050.degree.
F.+(.about.566.degree. C.+) vacuum resid fractions by
hydroprocessing and/or hydrocracking can be limited by
incompatibility. Under conventional understanding, at somewhere
between .about.30 wt % and .about.55 wt % conversion of the
.about.1050.degree. F.+(.about.566.degree. C.+) portion, the
reaction product during hydroprocessing can become incompatible
with the feed. For example, as the .about.566.degree. C.+ feedstock
converts to .about.1050.degree. F.- (.about.566.degree. C.-)
products, hydrogen transfer, oligomerization, and dealkylation
reactions can occur which create molecules that are increasingly
difficult to keep in solution. Somewhere between .about.30 wt % and
.about.55 wt % .about.566.degree. C.+ conversion, a second liquid
hydrocarbon phase separates. This new incompatible phase, under
conventional understanding, can correspond to mostly polynuclear
aromatics rich in N, S, and metals. The new incompatible phase can
potentially be high in micro carbon residue (MCR). The new
incompatible phase can stick to surfaces in the unit where it cokes
and then can foul the equipment. Based on this conventional
understanding, catalytic slurry oil can conventionally be expected
to exhibit properties similar to a vacuum resid fraction during
hydroprocessing. Based on the above conventional understanding, it
can be expected that hydroprocessing of a catalytic slurry oil
would cause incompatibility as the asphaltenes and/or
.about.566.degree. C.+ material converts.
[0028] In contrast to conventional understanding, it has been
discovered that hydroprocessing can be performed while reducing or
minimizing the above difficulties by exposing the heavy cracked
feed, in sequence, to a first mixed metal catalyst comprising Ni
and Mo, a second mixed metal catalyst comprising Ni and W, and a
third catalyst comprising a zeolite-based hydrocracking catalyst in
a single reaction stage. A heavy cracked feed can be processed as
part of a feed where the heavy cracked feed corresponds to at least
about 25 wt % of the feed to a process for forming fuels, such as
at least about 50 wt %, at least about 75 wt %, at least about 90
wt %, or at least about 95 wt %. Optionally, the feed can
correspond to at least about 99 wt % of a heavy cracked feed,
therefore corresponding to a feed that consists essentially of
heavy cracked feed. In particular, a feed can comprise about 25 wt
% to about 100 wt % heavy cracked feed, or about 25 wt % to about
99 wt %, or about 50 wt % to about 90 wt %. It has been
unexpectedly discovered that this sequential exposure of the heavy
cracked feed to the catalysts at effective hydroprocessing
conditions results in substantial conversion of the feed without
causing excessive coking of the catalyst or differential pressure
build across the hydroprocessing reactor, which would be indicative
of asphaltene precipitation.
[0029] Typically the cut point for forming a heavy cracked feed can
be at least about 650.degree. F. (.about.343.degree. C.). As a
result, a heavy cracked feed can have a T5 distillation (boiling)
point or a T10 distillation point of at least about 288.degree. C.,
or at least about 316.degree. C., or at least about 650.degree. F.
(.about.343.degree. C.), as measured according to ASTM D2887. In
some aspects the D2887 10% distillation point (T10) can be greater,
such as at least about 675.degree. F. (.about.357.degree. C.), or
at least about 700.degree. F. (.about.371.degree. C.). In some
aspects, a broader boiling range portion of FCC products can be
used as a feed (e.g., a 350.degree. F.+/.about.177.degree. C.+
boiling range fraction of FCC liquid product), where the broader
boiling range portion includes a 650.degree. F.+(.about.343.degree.
C.+) fraction that corresponds to a heavy cracked feed. The heavy
cracked feed (650.degree. F.+/.about.343.degree. C.+) fraction of
the feed does not necessarily have to represent a "bottoms"
fraction from an FCC process, so long as the heavy cracked feed
portion comprises one or more of the other feed characteristics
described herein.
[0030] In addition to and/or as an alternative to initial boiling
points, T5 distillation point, and/or T10 distillation points,
other distillation points may be useful in characterizing a
feedstock. For example, a feedstock can be characterized based on
the portion of the feedstock that boils above 1050.degree. F.
(.about.566.degree. C.). In some aspects, a feedstock (or
alternatively a 650.degree. F.+/.about.343.degree. C.+ portion of a
feedstock) can have an ASTM D2887 T95 distillation point of
1050.degree. F. (.about.566.degree. C.) or greater, or a T90
distillation point of 1050.degree. F. (.about.566.degree. C.) or
greater. If a feedstock or other sample contains components that
are not suitable for characterization using D2887, ASTM D1160 may
be used instead for such components.
[0031] In various aspects, density, or weight per volume, of the
heavy cracked feed can be characterized. The density of the heavy
cracked feed (or alternatively a 650.degree. F.+/.about.343.degree.
C.+ portion of a feedstock) can be at least about 1.06 g/cc, or at
least about 1.08 g/cc, or at least about 1.10 g/cc, such as up to
about 1.20 g/cc. The density of the heavy cracked feed can provide
an indication of the amount of heavy aromatic cores that are
present within the heavy cracked feed.
[0032] Contaminants such as organic nitrogen and organic sulfur are
typically found in heavy cracked feeds, often in organically-bound
form. Nitrogen content can range from about 50 wppm to about 5000
wppm elemental nitrogen, or about 100 wppm to about 2000 wppm
elemental nitrogen, or about 250 wppm to about 1000 wppm, based on
total weight of the heavy cracked feed. The nitrogen containing
compounds can be present as basic or non-basic nitrogen species.
Examples of nitrogen species can include quinolones, substituted
quinolones, carbazoles, and substituted carbazoles.
[0033] The sulfur content of a heavy cracked feed can be at least
about 500 wppm elemental sulfur, based on total weight of the heavy
cracked feed. Generally, the sulfur content of a heavy cracked feed
can range from about 500 wppm to about 100,000 wppm elemental
sulfur, or from about 1000 wppm to about 50,000 wppm, or from about
1000 wppm to about 30,000 wppm, based on total weight of the heavy
component. Sulfur may also be expressed as weight percent and can
range from about 0.5 wt % to about 6 wt %, or from about 1 wt % to
about 5 wt %, or about 2 wt % to about 4 wt %. Sulfur can usually
be present as organically bound sulfur. Examples of such sulfur
compounds include the class of heterocyclic sulfur compounds such
as thiophenes, tetrahydrothiophenes, benzothiophenes and their
higher homologs and analogs. Other organically bound sulfur
compounds include aliphatic, naphthenic, and aromatic mercaptans,
sulfides, di- and polysulfides.
[0034] A favorable feature of hydroprocessing a heavy cracked feed
can be the increase in product volume that can be achieved. Due to
the high percentage of aromatic cores in a heavy cracked feed,
hydroprocessing of heavy cracked feed can result in substantial
consumption of hydrogen. The additional hydrogen added to a heavy
cracked feed can result in an increase in volume for the
hydroprocessed heavy cracked feed or volume swell. For example, the
amount of C.sub.3+ liquid products generated from hydrotreatment
and FCC processing of catalytic slurry oil can be greater than
.about.100% of the volume of the initial catalytic slurry oil. (A
similar proportional increase in volume can be achieved for feeds
that include only a portion of deasphalted catalytic slurry oil.)
Hydroprocessing within the normal range of commercial hydrotreater
operations can enable .about.2000-4000 SCF/bbl (.about.340
Nm.sup.3/m.sup.3 to .about.680 m.sup.3/m.sup.3) of hydrogen to be
added to a feed corresponding to a deasphalted heavy cracked feed.
This can result in substantial conversion of a deasphalted heavy
cracked feed to .about.700.degree. F.- (.about.371.degree. C.-)
products, such as at least about 40 wt % conversion to
.about.371.degree. C.- products, or at least about 50 wt %, or at
least about 60 wt %, and up to about 90 wt % or more. In some
aspects, the .about.371.degree. C.- product can meet the
requirements for a low sulfur diesel fuel blendstock in the U.S.
Additionally or alternately, the .about.371.degree. C.- product(s)
can be upgraded by further hydroprocessing to a low sulfur diesel
fuel or blendstock. The remaining .about.700.degree.
F.+(.about.371.degree. C.+) product can meet the normal
specifications for a <.about.0.5 wt % S bunker fuel or a
<.about.0.1 wt % S bunker fuel, and/or may be blended with a
distillate range blendstock to produce a finished blend that can
meet the specifications for a <.about.0.1 wt % S bunker fuel.
Additionally or alternately, a .about.343.degree. C.+ product can
be formed that can be suitable for use as a <.about.0.1 wt % S
bunker fuel without additional blending. The additional hydrogen
for the hydrotreatment of the heavy cracked feed can be provided
from any convenient source.
[0035] Additionally or alternately, the remaining
.about.371.degree. C.+ product (and/or portions of the
.about.371.degree. C.+ product) can be used as feedstock to an FCC
unit and cracked to generate additional LPG, gasoline, and diesel
fuel, so that the yield of .about.371.degree. C.- products relative
to the total liquid product yield can be at least about 60 wt %, or
at least about 70 wt %, or at least about 80 wt %. Relative to the
feed, the yield of C.sub.3+ liquid products can be at least about
100 vol %, such as at least about 105 vol %, at least about 110 vol
%, at least about 115 vol %, or at least about 120 vol %. In
particular, the yield of C.sub.3+ liquid products can be about 100
vol % to about 150 vol %, or about 110 vol % to about 150 vol %, or
about 120 vol % to about 150 vol %.
[0036] More generally, the systems and methods described herein can
be used for processing feedstocks containing one or more types of
cracked feeds that have a high density prior to hydroprocessing,
such as a density of 1.04 g/cm.sup.3 or more, or 1.06 g/cm.sup.3 or
more, or 1.08 g/cm.sup.3 or more, such as up to 1.20 g/cm.sup.3 or
possibly still higher. Additionally or alternately, the feedstock
including one or more cracked feeds can have an aromatics content
of about 40 wt % to about 80 wt %, or about 40 wt % to about 70 wt
%, or about 50 wt % to about 80 wt %. In addition to catalytic
slurry oils, other types of cracked stocks include, but are not
limited to, heavy coker gas oils (such coker bottoms), steam
cracker tars, coal tars, and visbreaker gas oils.
[0037] For example, steam cracker tar (SCT) as used herein is also
referred to in the art as "pyrolysis fuel oil". The terms can be
used interchangeably herein. The tar will typically be obtained
from the first fractionator downstream from a steam cracker
(pyrolysis furnace) as the bottoms product of the fractionator,
nominally having a boiling point of at least about 550.degree.
F.+(.about.288.degree. C.+). Boiling points and/or fractional
weight distillation points can be determined by, for example, ASTM
D2892. Alternatively, SCT can have a T5 boiling point (temperature
at which 5 wt % will boil off) of at least about 550.degree. F.
(.about.288.degree. C.). The final boiling point of SCT can be
dependent on the nature of the initial pyrolysis feed and/or the
pyrolysis conditions, and typically can be about 1450.degree. F.
(.about.788.degree. C.) or less.
[0038] SCT can have a relatively low hydrogen content compared to
heavy oil fractions that are typically processed in a refinery
setting. In some aspects, SCT can have a hydrogen content of about
8.0 wt % or less, about 7.5 wt % or less, or about 7.0 wt % or
less, or about 6.5 wt % or less. In particular, SCT can have a
hydrogen content of about 5.5 wt % to about 8.0 wt %, or about 6.0
wt % to about 7.5 wt %. Additionally or alternately, SCT can have a
micro carbon residue (or alternatively Conradson Carbon Residue) of
at least about 10 wt %, or at least about 15 wt %, or at least
about 20 wt %, such as up to about 40 wt % or more.
[0039] SCT can also be highly aromatic in nature. The paraffin
content of SCT can be about 2.0 wt % or less, or about 1.0 wt % or
less, such as having substantially no paraffin content. The
naphthene content of SCT can also be about 2.0 wt % or less or
about 1.0 wt % or less, such as having substantially no naphthene
content. In some aspects, the combined paraffin and naphthene
content of SCT can be about 1.0 wt % or less. With regard to
aromatics, at least about 30 wt % of SCT can correspond to 3-ring
aromatics, or at least 40 wt %. In particular, the 3-ring aromatics
content can be about 30 wt % to about 60 wt %, or about 40 wt % to
about 55 wt %, or about 40 wt % to about 50 wt %. Additionally or
alternately, at least about 30 wt % of SCT can correspond to 4-ring
aromatics, or at least 40 wt %. In particular, the 4-ring aromatics
content can be about 30 wt % to about 60 wt %, or about 40 wt % to
about 55 wt %, or about 40 wt % to about 50 wt %. Additionally or
alternately, the 1-ring aromatic content can be about 15 wt % or
less, or about 10 wt % or less, or about 5 wt % or less, such as
down to about 0.1 wt %.
[0040] SCT can also have a higher density than many types of crude
or refinery fractions. In various aspects, SCT can have a density
at 15.degree. C. of about 1.08 g/cm.sup.3 to about 1.20 g/cm.sup.3,
or 1.10 g/cm.sup.3 to 1.18 g/cm.sup.3. By contrast, many types of
vacuum resid fractions can have a density of about 1.05 g/cm.sup.3
or less. Additionally or alternately, density (or weight per
volume) of the heavy hydrocarbon can be determined according to
ASTM D287-92 (2006) Standard Test Method for API Gravity of Crude
Petroleum and Petroleum Products (Hydrometer Method), which
characterizes density in terms of API gravity. In general, the
higher the API gravity, the less dense the oil. API gravity can be
5.degree. or less, or 0.degree. or less, such as down to about
-10.degree. or lower.
[0041] Contaminants such as nitrogen and sulfur are typically found
in SCT, often in organically-bound form. Nitrogen content can range
from about 50 wppm to about 10,000 wppm elemental nitrogen or more,
based on total weight of the SCT. Sulfur content can range from
about 0.1 wt % to about 10 wt %, based on total weight of the
SCT.
[0042] Coker bottoms represent another type of cracked feed
suitable for hydroprocessing, optionally in combination with a
catalytic slurry oil and/or steam cracker tar and/or other cracked
fractions. Coking is a thermal cracking process that is suitable
for conversion of heavy feeds into fuels boiling range products.
The feedstock to a coker typically also includes 5 wt % to 25 wt %
recycled product from the coker, which can be referred to as coker
bottoms. This recycle fraction allows metals, asphaltenes,
micro-carbon residue, and/or other solids to be returned to the
coker, as opposed to being incorporated into a coker gas oil
product. This can maintain a desired product quality for the coker
gas oil product, but results in a net increase in the amount of
light ends and coke that are generated by a coking process. The
coker bottoms can correspond to a fraction with a T10 distillation
point of at least 550.degree. F. (288.degree. C.), or at least
300.degree. C., or at least 316.degree. C., and a T90 distillation
point of 566.degree. C. or less, or 550.degree. C. or less, or
538.degree. C. or less. The coker recycle fraction can have an
aromatic carbon content of about 20 wt % to about 50 wt %, or about
30 wt % to about 45 wt %, and a micro carbon residue content of
about 4.0 wt % to about 15 wt %, or about 6.0 wt % to about 15 wt
%, or about 4.0 wt % to about 10 wt %, or about 6.0 wt % to about
12 wt %.
Additional Feedstocks
[0043] In some aspects, at least a portion of a feedstock for
processing as described herein can correspond to a vacuum resid
fraction or another type 950.degree. F.+(510.degree. C.+) or
1000.degree. F.+(538.degree. C.+) fraction. Another example of a
method for forming a 950.degree. F.+(510.degree. C.+) or
1000.degree. F.+(538.degree. C.+) fraction is to perform a high
temperature flash separation. The 950.degree. F.+(510.degree. C.+)
or 1000.degree. F.+(538.degree. C.+) fraction formed from the high
temperature flash can be processed in a manner similar to a vacuum
resid.
[0044] A vacuum resid fraction or a 950.degree. F.+(510.degree.
C.+) fraction formed by another process (such as a flash
fractionation bottoms or a bitumen fraction) can be deasphalted at
low severity to form a deasphalted oil. Optionally, the feedstock
can also include a portion of a conventional feed for lubricant
base stock production, such as a vacuum gas oil.
[0045] A vacuum resid (or other 510.degree. C.+) fraction can
correspond to a fraction with a T5 distillation point (ASTM D2892,
or ASTM D7169 if the fraction will not completely elute from a
chromatographic system) of at least about 900.degree. F.
(482.degree. C.), or at least 950.degree. F. (510.degree. C.), or
at least 1000.degree. F. (538.degree. C.). Alternatively, a vacuum
resid fraction can be characterized based on a T10 distillation
point (ASTM D2892/D7169) of at least about 900.degree. F.
(482.degree. C.), or at least 950.degree. F. (510.degree. C.), or
at least 1000.degree. F. (538.degree. C.).
[0046] Resid (or other 510.degree. C.+) fractions can be high in
metals. For example, a resid fraction can be high in total nickel,
vanadium and iron contents. In an aspect, a resid fraction can
contain at least 0.00005 grams of Ni/V/Fe (50 wppm) or at least
0.0002 grams of Ni/V/Fe (200 wppm) per gram of resid, on a total
elemental basis of nickel, vanadium and iron. In other aspects, the
heavy oil can contain at least 500 wppm of nickel, vanadium, and
iron, such as up to 1000 wppm or more.
[0047] Contaminants such as nitrogen and sulfur are typically found
in resid (or other 510.degree. C.+) fractions, often in
organically-bound form. Nitrogen content can range from about 50
wppm to about 10,000 wppm elemental nitrogen or more, based on
total weight of the resid fraction. Sulfur content can range from
500 wppm to 100,000 wppm elemental sulfur or more, based on total
weight of the resid fraction, or from 1000 wppm to 50,000 wppm, or
from 1000 wppm to 30,000 wppm.
[0048] Still another method for characterizing a resid (or other
510.degree. C.+) fraction is based on the Conradson carbon residue
(CCR) of the feedstock. The Conradson carbon residue of a resid
fraction can be at least about 5 wt %, such as at least about 10 wt
% or at least about 20 wt %. Additionally or alternately, the
Conradson carbon residue of a resid fraction can be about 50 wt %
or less, such as about 40 wt % or less or about 30 wt % or
less.
Hydroprocessing of Feedstock Including One or More Cracked
Fractions
[0049] A feedstock including one or more cracked fractions can be
hydroprocessed to form a hydroprocessed effluent. This can include
hydrotreatment and/or hydrocracking to remove heteroatoms (such as
sulfur and/or nitrogen) to desired levels, reduce Conradson Carbon
content, and/or provide viscosity index (VI) uplift. Additionally
or alternately, the hydroprocessing can be performed to achieve a
desired level of conversion of higher boiling compounds in the feed
to fuels boiling range compounds. Depending on the aspect, a
feedstock can be hydroprocessed by demetallization, aromatics
saturation, hydrotreating, hydrocracking, or a combination
thereof.
[0050] In various aspects, the aromatics content of the feedstock
can be at least 50 wt %, or at least 55 wt %, or at least 60 wt %,
or at least 65 wt %, or at least 70 wt %, or at least 75 wt %, such
as up to 90 wt % or more. Additionally or alternately, the
saturates content of the feedstock can be 50 wt % or less, or 45 wt
% or less, or 40 wt % or less, or 35 wt % or less, or 30 wt % or
less, or 25 wt % or less, such as down to 10 wt % or less. In this
discussion and the claims below, the aromatics content and/or the
saturates content of a fraction can be determined based on ASTM
D7419.
[0051] Depending on the aspect, the hydroprocessing can be
performed in a configuration including a single reaction stage. The
reaction conditions during demetallization and/or hydrotreatment
and/or hydrocracking of the feedstock can be selected to generate a
desired level of conversion of a feed. Any convenient type of
reactor, such as fixed bed (for example trickle bed) reactors can
be used. Conversion of the feed can be defined in terms of
conversion of molecules that boil above a temperature threshold to
molecules below that threshold. The conversion temperature can be
any convenient temperature, such as .about.700.degree. F.
(371.degree. C.) or 1050.degree. F. (566.degree. C.). The amount of
conversion can correspond to the total conversion of molecules
within the combined hydrotreatment and hydrocracking stages.
Suitable amounts of conversion of molecules boiling above
1050.degree. F. (566.degree. C.) to molecules boiling below
566.degree. C. include 30 wt % to 100 wt % conversion relative to
566.degree. C., or 30 wt % to 90 wt %, or 30 wt % to 70 wt %, or 40
wt % to 90 wt %, or 40 wt % to 80 wt %, or 40 wt % to 70 wt %, or
50 wt % to 100 wt %, or 50 wt % to 90 wt %, or 50 wt % to 70 wt %.
In particular, the amount of conversion relative to 566.degree. C.
can be 30 wt % to 100 wt %, or 50 wt % to 100 wt %, or 40 wt % to
90 wt %. Additionally or alternately, suitable amounts of
conversion of molecules boiling above .about.700.degree. F.
(371.degree. C.) to molecules boiling below 371.degree. C. include
10 wt % to 70 wt % conversion relative to 371.degree. C., or 10 wt
% to 60 wt %, or 10 wt % to 50 wt %, or 20 wt % to 70 wt %, or 20
wt % to 60 wt %, or 20 wt % to 50 wt %, or 30 wt % to 70 wt %, or
30 wt % to 60 wt %, or 30 wt % to 50 wt %. In particular, the
amount of conversion relative to 371.degree. C. can be 10 wt % to
70 wt %, or 20 wt % to 50 wt %, or 30 wt % to 60 wt %.
[0052] The hydroprocessed effluent can also be characterized based
on the product quality. After hydroprocessing (hydrotreating and/or
hydrocracking), the liquid (C.sub.3+) portion of the hydroprocessed
deasphalted oil/hydroprocessed effluent can have a sulfur content
of about 1000 wppm or less, or about 500 wppm or less, or about 100
wppm or less (such as down to .about.0 wppm). Additionally or
alternately, the hydroprocessed deasphalted oil/hydroprocessed
effluent can have a nitrogen content of 200 wppm or less, or 100
wppm or less, or 50 wppm or less (such as down to .about.0 wppm).
Additionally or alternately, the liquid (C.sub.3+) portion of the
hydroprocessed deasphalted oil/hydroprocessed effluent can have a
MCR content and/or Conradson Carbon residue content of 2.5 wt % or
less, or 1.5 wt % or less, or 1.0 wt % or less, or 0.7 wt % or
less, or 0.1 wt % or less, or 0.02 wt % or less (such as down to
.about.0 wt %). MCR content and/or Conradson Carbon residue content
can be determined according to ASTM D4530.
[0053] In some aspects, the portion of the hydroprocessed effluent
having a boiling range/distillation point of less than about
700.degree. F. (.about.371.degree. C.) can be used as a low sulfur
fuel oil or blendstock for low sulfur fuel oil. In other aspects,
such a portion of the hydroprocessed effluent can be used
(optionally with other distillate streams) to form ultra-low sulfur
naphtha and/or distillate (such as diesel) fuel products, such as
ultra-low sulfur fuels or blendstocks for ultra-low sulfur fuels.
The portion having a boiling range/distillation point of at least
about 700.degree. F. (.about.371.degree. C.) can be used as an
ultra-low sulfur fuel oil having a sulfur content of about 0.1 wt %
or less or optionally blended with other distillate or fuel oil
streams to form an ultra-low sulfur fuel oil or a low sulfur fuel
oil. In some aspects, at least a portion of the liquid hydrotreated
effluent having a distillation point of at least about
.about.371.degree. C. can be used as a feed for FCC processing. In
still other aspects, the portion having a boiling
range/distillation point of at least about 371.degree. C. can be
used as a feedstock for lubricant base oil production.
[0054] In various aspects, the feedstock can be exposed to uniquely
oriented stacked beds of hydrotreating catalyst under effective
hydrotreating conditions in a single reaction stage. The catalysts
used can include conventional hydroprocessing catalysts, such as
those comprising at least one Group VIII non-noble metal (Columns
8-10 of IUPAC periodic table), preferably Fe, Co, and/or Ni, such
as Co and/or Ni; and at least one Group VI metal (Column 6 of IUPAC
periodic table), preferably Mo and/or W. Such hydroprocessing
catalysts optionally include transition metal sulfides that are
impregnated or dispersed on a refractory support or carrier such as
alumina and/or silica. The support or carrier itself typically has
no significant/measurable catalytic activity. Substantially
carrier- or support-free catalysts, commonly referred to as bulk
catalysts, generally have higher volumetric activities than their
supported counterparts. In a preferred embodiment, the heavy
cracked feed is exposed in order to a first bulk or supported mixed
metal catalyst comprising Ni and Mo, a second bulk or supported
mixed metal catalyst comprising Ni and W, and a third catalyst
comprising a zeolite-based hydrocracking catalyst.
[0055] The catalysts can either be in bulk form or in supported
form. In addition to alumina and/or silica, other suitable
support/carrier materials can include, but are not limited to,
zeolites, titania, silica-titania, and titania-alumina. Suitable
aluminas are porous aluminas such as gamma or eta having average
pore sizes from 50 to 200 .ANG., or 75 to 150 .ANG. (as determined
by ASTM D4284); a surface area (as measured by the BET method) from
100 to 300 m.sup.2/g, or 150 to 250 m.sup.2/g; and a pore volume of
from 0.25 to 1.0 cm.sup.3/g, or 0.35 to 0.8 cm.sup.3/g. More
generally, any convenient size, shape, and/or pore size
distribution for a catalyst suitable for hydrotreatment of a
distillate (including lubricant base stock) boiling range feed in a
conventional manner may be used. Preferably, the support or carrier
material is an amorphous support, such as a refractory oxide.
Preferably, the support or carrier material can be free or
substantially free of the presence of molecular sieve, where
substantially free of molecular sieve is defined as having a
content of molecular sieve of less than about 0.01 wt %.
[0056] The at least one Group VIII non-noble metal, in oxide form,
can typically be present in an amount ranging from about 2 wt % to
about 40 wt %, preferably from about 4 wt % to about 15 wt %. The
at least one Group VI metal, in oxide form, can typically be
present in an amount ranging from about 2 wt % to about 70 wt %,
preferably for supported catalysts from about 6 wt % to about 40 wt
% or from about 10 wt % to about 30 wt %. These weight percents are
based on the total weight of the catalyst. Suitable metal catalysts
include nickel/molybdenum (1-10% Ni as oxide, 10-40% Mo as oxide),
or nickel/tungsten (1-10% Ni as oxide, 10-40% W as oxide) on
alumina, silica, silica-alumina, or titania.
[0057] The hydroprocessing is carried out in the presence of
hydrogen. A hydrogen stream is, therefore, fed or injected into a
vessel or reaction zone or hydroprocessing zone in which the
hydroprocessing catalyst is located. Hydrogen, which is contained
in a hydrogen "treat gas," is provided to the reaction zone. Treat
gas, as referred to herein, can be either pure hydrogen or a
hydrogen-containing gas, which is a gas stream containing hydrogen
in an amount that is sufficient for the intended reaction(s),
optionally including one or more other gasses (e.g., nitrogen and
light hydrocarbons such as methane). The treat gas stream
introduced into a reaction stage will preferably contain at least
about 50 vol. % and more preferably at least about 75 vol. %
hydrogen. Optionally, the hydrogen treat gas can be substantially
free (less than 1 vol %) of impurities such as H.sub.2S and
NH.sub.3 and/or such impurities can be substantially removed from a
treat gas prior to use.
[0058] Hydrogen can be supplied at a rate of from about 100 SCF/B
(standard cubic feet of hydrogen per barrel of feed) (17
Nm.sup.3/m.sup.3) to about 15000 SCF/B (1700 Nm.sup.3/m.sup.3).
Preferably, the hydrogen is provided in a range of from about 2000
SCF/B (340 Nm.sup.3/m.sup.3) to about 12000 SCF/B (2040
Nm.sup.3/m.sup.3). Hydrogen can be supplied co-currently with the
input feed to the hydrotreatment reactor and/or reaction zone or
separately via a separate gas conduit to the hydrotreatment
zone.
[0059] Hydrotreating conditions can include temperatures of
200.degree. C. to 450.degree. C., or 315.degree. C. to 425.degree.
C.; pressures of 250 psig (1.8 MPag) to 5000 psig (34.6 MPag) or
300 psig (2.1 MPag) to 3000 psig (20.8 MPag), or about 2.9 MPag to
about 13.9 MPag (.about.400 to .about.2000 psig); liquid hourly
space velocities (LHSV) of 0.1 hr.sup.-1 to 10 hr.sup.-1, or 0.1
hr.sup.-1 to 5.0 hr'; and a hydrogen treat gas rate of from about
430 to about 2600 Nm.sup.3/m.sup.3 (.about.2500 to .about.15000
SCF/bbl), or about 850 to about 1700 Nm.sup.3/m.sup.3 (.about.5000
to .about.10000 SCF/bbl).
[0060] In various aspects, the feedstock can be exposed to a
hydrocracking catalyst under effective hydrocracking conditions.
Hydrocracking catalysts typically contain sulfided base metals on
acidic supports, such as amorphous silica alumina, cracking
zeolites such as USY, or acidified alumina. Often these acidic
supports are mixed or bound with other metal oxides such as
alumina, titania or silica. Examples of suitable acidic supports
include acidic molecular sieves, such as zeolites or
silicoaluminophophates. One example of suitable zeolite is USY,
such as a USY zeolite with cell size of 24.30 Angstroms or less.
Additionally or alternately, the catalyst can be a low acidity
molecular sieve, such as a USY zeolite with a Si to Al ratio of at
least about 20, and preferably at least about 40 or 50. ZSM-48,
such as ZSM-48 with a SiO.sub.2 to Al.sub.2O.sub.3 ratio of about
110 or less, such as about 90 or less, is another example of a
potentially suitable hydrocracking catalyst. Still another option
is to use a combination of USY and ZSM-48. Still other options
include using one or more of zeolite Beta, ZSM-5, ZSM-35, or
ZSM-23, either alone or in combination with a USY catalyst.
Non-limiting examples of metals for hydrocracking catalysts include
metals or combinations of metals that include at least one Group
VIII metal, such as nickel, nickel-cobalt-molybdenum,
cobalt-molybdenum, nickel-tungsten, nickel-molybdenum, and/or
nickel-molybdenum-tungsten. Additionally or alternately,
hydrocracking catalysts with noble metals can also be used.
Non-limiting examples of noble metal catalysts include those based
on platinum and/or palladium. Support materials which may be used
for both the noble and non-noble metal catalysts can comprise a
refractory oxide material such as alumina, silica, alumina-silica,
kieselguhr, diatomaceous earth, magnesia, zirconia, or combinations
thereof, with alumina, silica, alumina-silica being the most common
(and preferred, in one embodiment).
[0061] When only one hydrogenation metal is present on a
hydrocracking catalyst, the amount of that hydrogenation metal can
be at least about 0.1 wt % based on the total weight of the
catalyst, for example at least about 0.5 wt % or at least about 0.6
wt %. Additionally or alternately when only one hydrogenation metal
is present, the amount of that hydrogenation metal can be about 5.0
wt % or less based on the total weight of the catalyst, for example
about 3.5 wt % or less, about 2.5 wt % or less, about 1.5 wt % or
less, about 1.0 wt % or less, about 0.9 wt % or less, about 0.75 wt
% or less, or about 0.6 wt % or less. Further additionally or
alternately when more than one hydrogenation metal is present, the
collective amount of hydrogenation metals can be at least about 0.1
wt % based on the total weight of the catalyst, for example at
least about 0.25 wt %, at least about 0.5 wt %, at least about 0.6
wt %, at least about 0.75 wt %, or at least about 1 wt %. Still
further additionally or alternately when more than one
hydrogenation metal is present, the collective amount of
hydrogenation metals can be about 35 wt % or less based on the
total weight of the catalyst, for example about 30 wt % or less,
about 25 wt % or less, about 20 wt % or less, about 15 wt % or
less, about 10 wt % or less, or about 5 wt % or less. In
embodiments wherein the supported metal comprises a noble metal,
the amount of noble metal(s) is typically less than about 2 wt %,
for example less than about 1 wt %, about 0.9 wt % or less, about
0.75 wt % or less, or about 0.6 wt % or less. It is noted that
hydrocracking under sour conditions is typically performed using a
base metal (or metals) as the hydrogenation metal.
[0062] A hydrocracking process under sour conditions can be carried
out at temperatures of about 550.degree. F. (288.degree. C.) to
about 840.degree. F. (449.degree. C.), hydrogen partial pressures
of from about 1500 psig to about 5000 psig (10.3 MPag to 34.6
MPag), liquid hourly space velocities of from 0.05 h.sup.-1 to 10
h.sup.-1, and hydrogen treat gas rates of from 35.6 m.sup.3/m.sup.3
to 2670 m.sup.3/m.sup.3 (200 SCF/B to 15,000 SCF/B). In other
embodiments, the conditions can include temperatures in the range
of about 600.degree. F. (343.degree. C.) to about 815.degree. F.
(435.degree. C.), hydrogen partial pressures of from about 1500
psig to about 3000 psig (10.3 MPag-20.9 MPag), and hydrogen treat
gas rates of from about 213 m.sup.3/m.sup.3 to about 1780
m.sup.3/m.sup.3 (1200 SCF/B to 10,000 SCF/B). The LHSV can be from
about 0.25 h.sup.-1 to about 50 h.sup.-1, or from about 0.5
h.sup.-1 to about 20 preferably from about 0.25 h.sup.-1 to about
4.0 h.sup.-1.
Deasphalting Heavy Cracked Feeds
[0063] In various aspects, the heavy cracked feed can be a
deasphalted heavy cracked feed. Deasphalting of heavy hydrocarbons,
such as vacuum resids, is known in the art and practiced
commercially. A deasphalting process typically corresponds to
contacting a heavy hydrocarbon with an alkane solvent (propane,
butane, pentane, hexane, heptane etc. and their isomers), either in
pure form or as mixtures, to produce two types of product streams.
One type of product stream can be a deasphalted oil extracted by
the alkane, which is further separated to produce deasphalted oil
stream. A second type of product stream can be a residual portion
of the feed not soluble in the solvent, often referred to as rock
or asphaltene fraction. The deasphalted oil fraction can be further
processed into make fuels or lubricants. The rock fraction can be
further used as blend component to produce asphalt, fuel oil,
and/or other products. The rock fraction can also be used as feed
to gasification processes such as partial oxidation, fluid bed
combustion or coking processes. The rock can be delivered to these
processes as a liquid (with or without additional components) or
solid (either as pellets or lumps).
[0064] During solvent deasphalting, the input feed to the solvent
deasphalting unit can be mixed with a solvent. Portions of the feed
that are soluble in the solvent are then extracted, leaving behind
a residue with little or no solubility in the solvent. The portion
of the deasphalted feedstock that is extracted with the solvent is
often referred to as deasphalted oil. Typical solvent deasphalting
conditions include mixing a feedstock fraction with a solvent in a
weight ratio of from about 1:2 to about 1:10, such as about 1:8 or
less. Typical solvent deasphalting temperatures range from
40.degree. C. to 200.degree. C., or 40.degree. C. to 150.degree.
C., depending on the nature of the feed and the solvent. The
pressure during solvent deasphalting can be from about 50 psig
(.about.345 kPag) to about 1000 psig (.about.6900 kPag).
Examples of Reactor Configurations
[0065] Provided herein is a unique multi-layered reactor for
treatment of heavy cracked feeds. Exemplary beds are provided in
the in the figures. In preferred cases, the reactor comprises a
first bulk or supported mixed metal catalyst comprising Ni and Mo,
a second bulk or supported mixed metal catalyst comprising Ni and
W, and a third catalyst comprising a zeolite-based hydrocracking
catalyst. As shown in the figures, the third catalyst may comprise
a hydrocracking catalyst (FIG. 1), a mixture of hydrocracking
catalyst and arosat catalyst (FIG. 4), and/or a noble metal
containing catalyst (FIG. 6). The reactor configurations and
benefits of the present disclosure can be better understood with
reference to the examples.
Example 1--Hydrocracking Catalysts for Heavy Cracked Feeds
[0066] A raw fluid catalytic cracking (FCC) main column bottoms
(MCB) was obtained for catalytic testing of combined
hydrotreating/hydrocracking catalysts systems. The raw MCB
feedstock had the following properties
TABLE-US-00001 TABLE 1 Raw MCB Feed Properties Property Value
T.sub.10 674.degree. F. (356.degree. C.) T.sub.50 792.degree. F.
(426.degree. C.) T.sub.90 984.degree. F. (528.degree. C.) Density
1.11 g/cc Sulfur 2.8 wt % Nitrogen 1750 ppm
[0067] The raw MCB stream from Table 1 was used as a feedstock for
a pilot scale processing plant. The MCB was exposed to four
different catalyst beds, which are shown in FIG. 1. From left to
right, the first, second, and third beds include a stacked bed
configurations including an initial layer bulk metal hydrotreating
catalyst comprising Ni and Mo followed by a second layer of
hydrotreating catalyst comprising Ni and W, which in turn is
followed by a third and final layer of zeolite-based hydrocracking
catalyst. The only variance between these stacked beds occurs in
the third and final layer. The first bed contains a 1 wt % Pt
hydrocracking catalyst exhibiting a FAU framework on a
silica-alumina support with a silica to alumina ratio of about 20.
The second bed contains a commercially available hydrocracking
catalyst comprising Ni and W exhibiting a FAU framework. The third
bed contains a 0.6 wt % Pt hydrocracking catalyst exhibiting a FAU
framework on a silica-alumina support with a silica to alumina
ratio of about 200. The fourth bed is a control containing only a
single layer of bulk metal hydrotreating catalyst comprising Ni and
Mo.
[0068] The conditions for the run included a constant pressure of
about 2175 psig (15 MPa) and about 10,000 SCF/B of hydrogen treat
gas. Temperature and liquid hourly space velocity (LHSV) were
varied between 680.degree. F.-700.degree. F. (360.degree.
C.-371.degree. C.) and 0.25 h.sup.--0.5 h.sup.-1, respectively. The
results are shown in FIGS. 2A-F. The feed was processed in the
pilot plant for about 47 days with an initial temperature of
680.degree. F. (360.degree. C.) and LHSV of 0.25 h.sup.-1. At about
Day 37, temperature was increased to 700.degree. F. (371.degree.
C.). At about Day 43, LHSV was increased to 0.5 h.sup.-1. As shown
in FIGS. 2A and 2B, the stacked configuration generally results in
comparable or better conversion of 700.degree. F.+ molecules and
lower density than using bulk metal hydrotreating catalyst
comprising Ni and Mo alone. Remaining data related to naphtha
yield, distillate yield, sulfur content, and nitrogen content are
generally comparable and within acceptable ranges.
Example 2--Hydrocracking Catalysts for Deasphalted Heavy Cracked
Feeds
[0069] A deasphalted fluid catalytic cracking (FCC) main column
bottoms (MCB) was obtained for catalytic testing of combined
hydrotreating/hydrocracking catalysts systems. The deasphalted MCB
feedstock had the following properties
TABLE-US-00002 TABLE 2 Deasphalted MCB Feed Properties Property
Value T.sub.10 687.degree. F. (363.degree. C.) T.sub.50 779.degree.
F. (415.degree. C.) T.sub.90 916.degree. F. (491.degree. C.)
Density 1.13 g/cc Sulfur 4.6 wt % Nitrogen 2390 ppm
[0070] The MCB was exposed to the same four catalyst beds as
Example 1, which are shown in FIG. 1. The conditions for the run
included a constant pressure of about 2175 psig (15 MPa) and about
10,000 SCF/B of hydrogen treat gas. Temperature and liquid hourly
space velocity (LHSV) were varied between 680.degree.
F.-700.degree. F. (360.degree. C.-371.degree. C.) and 0.25
h.sup.-1-0.5 h.sup.-1, respectively. The results are shown in FIGS.
3A-F. The feed was processed in the pilot plant for about 25 days
with an initial temperature of 700.degree. F. (371.degree. C.) and
LHSV of 0.5 h.sup.-1. At about Day 13, LHSV was decreased to 0.25
h.sup.-1. At about Day 18, temperature was decreased to 680.degree.
F. (360.degree. C.). The advantages of the stacked bed
configurations are particularly telling in the context of the
deasphalted MCB. As shown in FIGS. 3A and 3B, the stacked
configuration results in better conversion of 700.degree. F.+
molecules and lower density than using bulk metal hydrotreating
catalyst comprising Ni and Mo alone in all cases. Remaining data
related to naphtha yield, distillate yield, sulfur content, and
nitrogen content are generally comparable and within acceptable
ranges. Examples 1 and 2 prove the discovery that a combination of
bulk-metal hydrotreating catalyst followed by zeolitic,
metal-containing, hydrocracking catalyst can achieve high yields of
ULSD blendstock and reduce 700.degree. F.+ range material. This is
non-intuitive for a single reaction stage because conventional
wisdom would dictate that the use of such zeolitic,
metal-containing, hydrocracking catalysts would be ineffective due
to rapid poisoning of the catalyst.
Example 3--Hydrocracking/Arosat Catalysts for Deasphalted Heavy
Cracked Feeds
[0071] A deasphalted FCC MCB was obtained for catalytic testing,
comparing several combination of NiMo and NiW bulk-metal
hydrotreating catalysts followed by mixtures of hydrocracking and
aromatic saturation ("arosat") catalysts. The deasphalted MCB
feedstock had the same properties as the deasphalted MCB feedstock
in Table 2 above.
[0072] The deasphalted MCB from Table 2 was used as a feedstock for
a pilot scale processing plant. The deasphalted MCB was exposed to
four different catalyst beds, which are shown in FIG. 4. From left
to right, the first, second, and third beds include a stacked bed
configurations including an initial layer bulk metal hydrotreating
catalyst comprising Ni and Mo followed by a second layer of
hydrotreating catalyst comprising Ni and W, which in turn is
followed by a third and final layer of mixed zeolite-based
hydrocracking catalyst and noble metal arosat catalyst. The final
layer of Bed 1 contains an equal mixture (by weight) of
approximately 1.0 wt % Pt impregnated on a FAU-type zeolite with an
SiO.sub.2/Al.sub.2O.sub.3 ratio of .about.20 in an extrudate with
commercially available alumina, and an arosat catalyst containing
both Pd and Pt (0.77 wt % and 0.25 wt %, respectively) on a
mesoporous aluminosilicate support with an
SiO.sub.2/Al.sub.2O.sub.3 ratio of .about.50. The final layer of
Bed 2 contains an equal mixture (by weight) of approximately 1.0 wt
% Pt impregnated on a FAU-type zeolite with an
SiO.sub.2/Al.sub.2O.sub.3 ratio of .about.60 in an extrudate with
commercially available alumina, and an arosat catalyst containing
both Pd and Pt (0.77 wt % and 0.25 wt %, respectively) on a
mesoporous aluminosilicate support with an
SiO.sub.2/Al.sub.2O.sub.3 ratio of .about.50. The final layer of
Bed 3 contains an equal mixture (by weight) of approximately 1.0 wt
% Pt impregnated on a FAU-type zeolite with an
SiO.sub.2/Al.sub.2O.sub.3 ratio of .about.20 in an extrudate with
commercially available alumina, and an arosat catalyst containing
2.0 wt % Pt on a 40 .ANG.-pore mesoporous aluminosilicate
support.
[0073] The conditions for the run included a constant pressure of
about 2175 prig (15 MPa) and about 10,000 SCF/B of hydrogen treat
gas. Temperature and liquid hourly space velocity (LHSV) were
varied between 680.degree. F.-700.degree. F. (360.degree.
C.-371.degree. C.) and 0.25 h.sup.-1-0.5 h.sup.-1, respectively.
The results are shown in FIGS. 5A-F. The feed was processed in the
pilot plant for about 25 days with an initial temperature of
700.degree. F. (371.degree. C.) and LHSV of 0.5 h.sup.-1. At about
Day 13, LHSV was decreased to 0.25 h.sup.-1. At about Day 18,
temperature was decreased to 680.degree. F. (360.degree. C.). The
advantages of the stacked bed configurations are particularly
telling in the context of the deasphalted MCB. As shown in FIGS. 5A
and 5B, the stacked configuration results in better conversion of
700.degree. F.+ molecules and lower density than using bulk metal
hydrotreating catalyst comprising Ni and Mo alone in all cases.
Remaining data related to naphtha yield, distillate yield, sulfur
content, and nitrogen content are generally comparable or better
and within acceptable ranges. Example 3 proves the discovery that a
combination of bulk-metal hydrotreating catalyst followed by a
hydrocracking/arosat mixed catalyst can achieve high yields of ULSD
blendstock and reduce 700.degree. F.+ range material. This is
non-intuitive for a single reaction stage because conventional
wisdom would dictate that the use of such a catalyst mixture would
be ineffective due to rapid poisoning of the catalyst.
Example 4--Noble Metal Catalysts and Mixed Catalysts for Heavy
Cracked Feeds
[0074] A raw FCC MCB was obtained for catalytic testing of combined
noble metal catalysts systems. The raw MCB feedstock had the same
properties as the raw MCB feedstock in Table 1 above.
[0075] The raw MCB from Table 1 was used as a feedstock for a pilot
scale processing plant. The MCB was exposed to seven different
catalyst beds, which are shown in FIG. 6. The stacked beds, beds
1-6, include an initial layer bulk metal hydrotreating catalyst
comprising Ni and Mo followed by a second layer of hydrotreating
catalyst comprising Ni and W, which in turn is followed by a third
and final layer containing one of six different noble-metal
hydrocracking, arosat, or combined hydrocracking/arosat
catalysts.
[0076] The final layer of Bed 1 is mesoporous aluminosilicate with
an SiO.sub.2/Al.sub.2O.sub.3 ratio of .about.50 containing a
mixture of Pd and Pt (0.77 wt % and 0.25 wt %, respectively). The
final layer of Bed 2 is zeolite-based (FAU), with an
SiO.sub.2/Al.sub.2O.sub.3 ratio of .about.200 and a Pt content of
0.6 wt % bound in an extrudate with commercially available alumina.
The final layer of Bed 3 is FAU-based, having an
SiO.sub.2/Al.sub.2O.sub.3 ratio of .about.20 and Pt content of 1.0
wt % bound in an extrudate with commercially available alumina. The
final layer of Bed 4 contains an equal mixture (by weight) of
approximately 1.0 wt % Pt impregnated on a FAU-type zeolite with an
SiO.sub.2/Al.sub.2O.sub.3 ratio of .about.20 in an extrudate with
commercially available alumina, and an arosat catalyst containing
both Pd and Pt (0.77 wt % and 0.25 wt %, respectively) on a
mesoporous aluminosilicate support with an
SiO.sub.2/Al.sub.2O.sub.3 ratio of .about.50. The final layer of
Bed 5 contains an equal mixture (by weight) of approximately 1.0 wt
% Pt impregnated on a FAU-type zeolite with an
SiO.sub.2/Al.sub.2O.sub.3 ratio of .about.60 in an extrudate with
commercially available alumina, and an arosat catalyst containing
both Pd and Pt (0.77 wt % and 0.25 wt %, respectively) on a
mesoporous aluminosilicate support with an
SiO.sub.2/Al.sub.2O.sub.3 ratio of .about.50. The final layer of
Bed 6 contains an equal mixture (by weight) of approximately 1.0 wt
% Pt impregnated on a FAU-type zeolite with an
SiO.sub.2/Al.sub.2O.sub.3 ratio of .about.20 in an extrudate with
commercially available alumina, and an arosat catalyst containing
2.0 wt % Pt on a 40 .ANG.-pore mesoporous aluminosilicate support.
Bed 7 is a bulk-metal NiMo hydrotreating catalyst used for
comparison to these stacked beds.
[0077] The conditions for the run included a constant pressure of
about 2175 psig (15 MPa) and about 10,000 SCF/B of hydrogen treat
gas. Temperature and liquid hourly space velocity (LHSV) were
varied between 680.degree. F.-700.degree. F. (360.degree.
C.-371.degree. C.) and 0.25 h.sup.-1-0.5 h.sup.-1, respectively.
The results are shown in FIGS. 7A-F. The feed was processed in the
pilot plant for about 47 days with an initial temperature of
680.degree. F. (360.degree. C.) and LHSV of 0.25 h.sup.-1. At about
Day 37, temperature was increased to 700.degree. F. (371.degree.
C.). At about Day 43, LHSV was increased to 0.5 h.sup.-1. As shown
in FIGS. 7A and 7B, the stacked configuration generally results in
comparable or better conversion of 700.degree. F.+ molecules and
lower density than using bulk metal hydrotreating catalyst
comprising Ni and Mo alone. Remaining data related to naphtha
yield, distillate yield, sulfur content, and nitrogen content are
generally comparable and within acceptable ranges.
Example 5--Noble Metal Catalysts and Mixed Catalysts for
Deasphalted Heavy Cracked Feeds
[0078] A deasphalted FCC MCB was obtained for catalytic testing,
comparing several combination of NiMo and NiW bulk-metal
hydrotreating catalysts followed by one of six different
noble-metal hydrocracking, arosat, or combined hydrocracking/arosat
catalysts. The deasphalted MCB feedstock had the same properties as
the deasphalted MCB feedstock in Table 2 above.
[0079] The deasphalted MCB was used as a feedstock for a pilot
scale processing plant. The deasphalted MCB was exposed to the same
seven catalyst beds as Example 4, which are shown in FIG. 6. The
conditions for the run included a constant pressure of about 2175
psig (15 MPa) and about 10,000 SCF/B of hydrogen treat gas.
Temperature and liquid hourly space velocity (LHSV) were varied
between 680.degree. F.-700.degree. F. (360.degree. C.-371.degree.
C.) and 0.25 h.sup.-1-0.5 h.sup.-1, respectively. The results are
shown in FIGS. 8A-F. The feed was processed in the pilot plant for
about 25 days with an initial temperature of 700.degree. F.
(371.degree. C.) and LHSV of 0.5 h.sup.-1. At about Day 13, LHSV
was decreased to 0.25 h.sup.-1. At about Day 18, temperature was
decreased to 680.degree. F. (360.degree. C.). The advantages of the
stacked bed configurations are particularly telling in the context
of the deasphalted MCB. As shown in FIGS. 8A and 8B, the stacked
configuration results in better conversion of 700.degree. F.+
molecules and lower density than using bulk metal hydrotreating
catalyst comprising Ni and Mo alone in nearly all cases. Remaining
data related to naphtha yield, distillate yield, sulfur content,
and nitrogen content are generally comparable or better and within
acceptable ranges. Example 3 proves the discovery that a
combination of bulk-metal hydrotreating catalyst followed by a
mixture of noble metal micro- and/or mesoporous hydrocracking and
arosat catalysts can achieve high yields of ULSD blendstock and
reduce 700.degree. F.+ range material. This is non-intuitive for a
single reaction stage because conventional wisdom would dictate
that the use of such a catalyst mixture would be ineffective due to
rapid poisoning of the catalyst.
Additional Embodiments
Embodiment 1
[0080] A process for upgrading a heavy cracked feedstock,
comprising: providing a feedstock comprising a density at
15.degree. C. of 1.06 g/cm.sup.3 or more, at least 50 wt % of one
or more 343.degree. C.+ cracked fractions, and a sulfur content of
0.8 to 5.0 wt % sulfur; in a single reaction stage under fixed bed
hydroprocessing conditions, exposing the feedstock to a first bulk
or supported mixed metal catalyst comprising Ni and Mo; exposing
the feedstock to a second bulk or supported mixed metal catalyst
comprising Ni and W; and exposing the feedstock to a third catalyst
comprising a zeolite-based hydrocracking catalyst.
Embodiment 2
[0081] The process of embodiment 1, wherein the zeolite-based
hydrocracking catalyst comprises a Group VIII noble metal.
Embodiment 3
[0082] The process of embodiment 2, wherein the zeolite-based
hydrocracking catalyst comprises 0.5 to 2.5 wt % Pt.
Embodiment 4
[0083] The process of any of the previous embodiments, wherein the
third catalyst further comprises an aromatic saturation catalyst
comprising Pd, Pt, or a combination thereof on an aluminosilicate
support.
Embodiment 5
[0084] The process of embodiment 4, wherein the aromatic saturation
catalyst comprises Pd and Pt in a wt % ratio of about 3:1 Pd to
Pt.
Embodiment 6
[0085] The process of embodiment 4 or 5, wherein the aromatic
saturation catalyst comprises 2.0 wt % Pt.
Embodiment 7
[0086] The process of any of the previous embodiments, wherein the
zeolite exhibits a faujasite (FAU) framework type.
Embodiment 8
[0087] The process of any of the previous embodiments, wherein the
feedstock comprises a density at 15.degree. C. of 1.1 g/cm.sup.3 or
more, a T.sub.10 of at least 343.degree. C. and a T90 of at least
475.degree. C.; and a sulfur content of 3.0 wt % to 5.0 wt %.
Embodiment 9
[0088] The process of any of the previous embodiments, wherein the
feedstock comprises a de-asphalted heavy cracked feedstock.
Embodiment 10
[0089] The process of any of the previous embodiments, wherein the
fixed bed hydroprocessing conditions include a temperature of
300.degree. C. to 400.degree. C., a pressure of 1500 psig to 3000
psig, a hydrogen treat gas rate of 2,000 scf/bbl to 12,000 scf/bbl,
and a LHSV of 0.2 h.sup.-1 to 1.5 h.sup.-1.
Embodiment 11
[0090] A system for processing a cracked feedstock comprising: a
hydroprocessing reactor comprising a hydroprocessing inlet, and a
hydroprocessing outlet, and a fixed bed comprising a first bulk or
supported mixed metal catalyst comprising Ni and Mo; a second bulk
or supported mixed metal catalyst comprising Ni and W; and a third
catalyst comprising a zeolite-based hydrocracking catalyst; wherein
the hydroprocessing inlet is designed to receive a feedstock
comprising a density at 15.degree. C. of 1.06 g/cm.sup.3 or more,
at least 50 wt % of one or more 343.degree. C.+ cracked fractions,
and a sulfur content of 1.0 to 5.0 wt % sulfur; and wherein the
fixed bed is oriented such that the feedstock contacts the first
catalyst, second catalyst, and third catalyst sequentially.
[0091] When numerical lower limits and numerical upper limits are
listed herein, ranges from any lower limit to any upper limit are
contemplated. While the illustrative embodiments of the invention
have been described with particularity, it will be understood that
various other modifications will be apparent to and can be readily
made by those skilled in the art without departing from the spirit
and scope of the invention. Accordingly, it is not intended that
the scope of the claims appended hereto be limited to the examples
and descriptions set forth herein but rather that the claims be
construed as encompassing all the features of patentable novelty
which reside in the present invention, including all features which
would be treated as equivalents thereof by those skilled in the art
to which the invention pertains.
[0092] The present invention has been described above with
reference to numerous embodiments and specific examples. Many
variations will suggest themselves to those skilled in this art in
light of the above detailed description. All such obvious
variations are within the full intended scope of the appended
claims.
* * * * *