Note: Descriptions are shown in the official language in which they were submitted.
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WO 97129841 PCT/US97/02409
LOW PRESSURE PROCESS FOR THE HYDROCONVERSION OF HEAVY
, HYDROCARBONS
s
Technical Field of the Invention
The present invention is generally directed to an improved process for the
hydroconversion or hydrocracking of heavy hydrocarbon oil feedstocks, heavy
whole petroleum
crude and heavy refinery residues. A stable process is achieved at reduced
pressure by the
~o inclusion of an oil soluble Group VI-B metal compound in the reactor feed.
The process is
preferably conducted at a total reactor pressure no greater than about 13,200
kPa (1900 psig) and
preferably from about 9065 kPa (1300 psig} to about 11,822 kPa (1700 psig).
Background Information
It is generally desired in the petroleum industry to convert heavy hydrocarbon
oil, that is
is petroleum fractions having an atmospheric boiling point above about
565° C. (1050° F.), into
lighter hydrocarbons which have higher economic value. In addition, the
petroleum industry
continues to desire a process that can convert heavy whole petroleum crude oil
to lighter crude
oil which has a substantially reduced amount of heavy hydrocarbon oil content.
Other
advantages sought through the treatment of heavy hydrocarbon oil, heavy whole
petroleum
2o crude oil and other similar feeds, particularly high boiling petroleum
refinery residues, include
hydrodesulfurization (HDS), hydrogenitrogenation (HDN), carbon residue ~
reduction (CRR),
hydrodemetallation (HDM) and sediment reduction.
Hydroconversion processes, also known and referred to herein as hydrocracking,
achieve
the above noted goals by reacting the feed oil with hydrogen gas in the
presence of a
2s heterogeneous transition metal catalyst. The heterogeneous transition metal
catalyst is typically
supported on high surface area refractory oxides such as alumina, silica,
alumino-silicates, and
others which should be known to one skilled in the art. Such catalyst supports
have complex
. surface pare structure which may include pores that are relatively small in
diameter (i.e.
micropares) and pores that are relatively large in diameter (i.e. macropores)
which effect the
so reaction characteristics of the catalyst. A considerable amount of research
into changing the
properties of hydroconversion catalysts by modifying the pare sizes, pore size
distribution, pore
CA 02244821 1998-07-27
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-2-
size ratios and other aspects of the catalyst surface has resulted in the
achievement of many of
the aforementioned goals of hydroconversion.
An ei~cellent example of such achievements is disclosed in U.S. Patent Number
,
5,435,908 Nelson et aI. in which a supported catalyst achieves good levels of
hydroconversion
s of heavy hydrocarbon feeds to products having an atmospheric boiling point
less than 538° C.
(1000° F.). Simultaneously, the catalyst and process disclosed produces
a liquid having an
atmospheric boiling point greater than 343° C {650° F) with a
low sediment content and a
product having an atmospheric boiling point greater than 538° C.
(1000° F.) having a low sulfur
content. The catalyst includes a Group VIII non-noble metal oxide and a Group
VI-B metal
lo oxide supported on alumina. The alumina support is characterized as having
a total Surface
Area of 150-240 m2lg, a Total Pore volume (TPV) of 0.7 to 0.98, and a Pore
Diameter
Distribution in which _< 20% of the TPV is present as primary micropores
having diameters less
than or equal to 100 ~, at least about 34% of the TPV is present as secondary
micropores having
diameters from about 100~r to 200A and about 26% to 46% of the TPV is present
as macropores
~ s having diameters greater than 200.
Another method to substantially achieve some of the above noted goals of the
hydroconversion of heavy oil feeds is disclosed in U.S. Patent Number
5,108,581 Aldrich et al.
As is disclosed by this reference, a dispersible or decomposable catalyst
precursor along with
hydrogen gas, preferably containing hydrogen sulfide, is added to the heavy
oil feed and the
2o mixture heated under pressure to form a catalyst concentrate. This catalyst
concentrate is then
added to the bulk of the heavy oil feed which is introduced into a
hydroconversion reactor.
Suitable conditions for the formation of the catalyst concentration include
temperatures of at
least 260° C. (500° F.) and elevated pressure from 170 kPa {10
psig) to 13,890 kPa {2000 psig)
with exemplary conditions being 380° C. (716° F.) and 9,754 kPa
(1400 psig). As is taught by
is the disclosure, the goal of such conditions is to decompose the catalyst
precursor so as to form .
solid catalyst particles dispersed in the hydrocarbon oil of the catalyst
concentrate before it is
mixed with the bulk of the heavy feed oil in the hydroconversion reactor. ,
Despite such advances, the hydroconversion process of heavy hydrocarbon oil
requires
elevated reactor temperatures (e.g. greater than 315° C. (600°
F.)) and high pressures (e.g. above
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- 3 -
13,890 kPa (2000 psig)) of hydrogen containing gas. Due to
the combination of elevated temperature and high pressures
of hydrogen gas, the costs of building and operating a
hydroconversion reactor are considerable. One way to reduce
these costs and to improve safety of the reactor is to lower
the reactor pressure. It is well known in the art that
operating a hydroconversion reaction at pressures below
13,890 kPa (2000 psig)) causes the formation of intractable
residues in the reactor and high levels of sediment in the
product stream. The collection of residues and other
sediments in the reactor and other process systems creates
reactor conditions that are unpredictable and unstable. If
this is to be avoided, frequent reactor shutdown and
cleaning is required which causes loss of production because
the reactor is not "on-line". Clearly unstable and
unpredictable reaction conditions are not desirable from a
product quality point of view, from a reactor operations
point of view or more importantly from a safety point of
view. Thus there remains an unmet need in the petroleum
industry for a stable hydroconversion process for heavy
hydrocarbon oil, heavy whole petroleum crude and heavy
refinery residues that yield lighter hydrocarbons under
pressure below 13,890 kPa (2000 psig).
Disclosure of the Invention
The present invention is generally directed to an
improved process for the hydroconversion or hydrocracking of
heavy hydrocarbon oil feedstocks, heavy whole petroleum
crude and other heavy refinery residues.
According to a broad aspect, the invention
provides a process of catalytic hydroconversion of a heavy
hydrocarbon oil containing a substantial portion of
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components having an atmospheric boiling point above about
565°C to give a product hydrocarbon oil containing a
substantial portion of components having a boiling point
below about 565°C, the process comprising: mixing the heavy
hydrocarbon oil with an oil soluble molybdenum compound,
wherein the molybdenum compound has a first decomposition
temperature of at least 222°C, to give a mixture having from
about 0.005 to about 0.050 weight percent molybdenum
compound; introducing the mixture into a hydroconversion
zone, the hydroconversion zone being at a temperature from
about 343°C to about 454°C and a total pressure from about
6996 kPa to about 24,233 kPa and containing a heterogeneous
catalyst, the catalyst including a Group VIII non-noble
metal oxide, and a Group VI-B metal oxide on an alumina or
silica-alumina support; introducing a reactor feed gas into
the hydroconversion zone, the reactor feed gas including a
majority of hydrogen gas, the introducing being conducted at
a rate from 356.2 liters (HZ)/liters (oil) to about
1782.2 liters (HZ)/liters (oil); and, recovering the product
hydrocarbon oil from the hydroconversion zone; wherein the
mixing of the heavy hydrocarbon oil with an oil soluble
molybdenum compound includes mixing a first portion of the
heavy hydrocarbon oil with the soluble molybdenum compound
to give a pre-feed mixture in which the concentration of
molybdenum compound is from about 0.02 to about 0.42 weight
percent, and mixing said pre-feed mixture with additional
heavy hydrocarbon oil to give a reactor feed mixture having
a concentration of molybdenum compound from about 0.005 to
about 0.050 weight percent.
According to another broad aspect, the invention
provides a method of hydrocracking a heavy whole petroleum
crude oil having at least 40 weight percent components
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boiling above about 565°C to give a processed crude oil
containing a majority of components boiling below about
565°C, the process comprising: mixing the heavy whole
petroleum crude with a oil soluble Group VI-B metal
compound, the metal compound having a first decomposition
temperature of at least 222°C, to give a reactor feed
mixture having from about 0.005 to about 0.050 weight
percent metal; reacting the mixture and a hydrogen
containing feed gas in an ebullated-bed reactor, the reactor
being at a temperature from about 343°C to about 454°C and
at a total pressure of no greater than about 13,201 kPa and
wherein the ebullated bed includes a supported heterogeneous
catalyst, the supported heterogeneous catalyst comprising a
Group VIII non-noble metal oxide, a Group VI-B metal oxide,
no more than 2 weight percent phosphorous oxide and an
alumina or silica-alumina support; and, recovering the
processed crude oil from the reactor; wherein the Group VI-B
metal compound in the reactor feed mixture contains
molybdenum; wherein the mixing of the heavy whole petroleum
crude oil with the oil soluble molybdenum compound comprises
combining a first portion of the heavy whole petroleum crude
oil with the oil soluble molybdenum compound to give a pre-
feed mixture in which the concentration of molybdenum
compound is from about 0.020 to about 0.420 weight percent,
and mixing said pre-feed mixture with additional heavy whole
petroleum crude oil to give a reactor feed mixture having a
concentration of molybdenum compound from about 0.005 to
about 0.050 weight percent.
In the following disclosure, it should be
understood that unless noted otherwise all boiling point
values are measured at atmospheric pressure.
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It is a particular feature of this invention that
it permits operation to be carried out under conditions
which yield a substantially decreased content of sediment in
the product stream leaving the hydroconversion zone.
The charge to a hydroconversion process is
typically characterized by a very low sediment content of
0.01 weight percent (wt %) maximum. Sediment is typically
measured by testing a sample by the Shell Hot Filtration
Solids Test (SHFST). See Jour. Inst. Pet. (1951) 37 pages
596-604 Van Kerknoort et al. Typical hydroprocessing
processes in the art commonly yield Shell Hot Filtration
Solids of above about 0.17 wt o and as high as about 1 wt o
in the 343°C+ (650°F+) product recovered from the bottoms
flash drum
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(BFD). Production of large amounts of sediment is undesirable in that it
results in deposition in
downstream units which in due course must be removed. This of course requires
that the unit be
shut down for an undesirable long period of time. Sediment is also undesirable
in the products '
because it deposits on and inside various pieces of equipment downstream of
the
s hydroprocessing unit and interferes with proper functioning of e.g. pumps,
heat exchangers,
fractionating tower, etc.
Very high levels of sediment formation (e.g., 1 wt % in the 343° C+
(650 F+) portion of
the hydroprocessed product), however, are not experienced by those refiners
who operate
vacuum resid hydroprocessing units at stable, moderate conversion levels of
feedstock
io components having boiling points greater than 538°C. (1000°
F) into products having boiling
points less than 538% (1000% F) (say, 40-65 volume percent - vol% -
conversion).
In the instant invention the IP 375/86 test method for the determination of
total sediment
has been very useful. The. test method is described in ASTM Designation D 4870-
92 -
incorporated herein by reference. the IP 375/86 method was designed for the
determination of
is total sediment in residual fuels and is very suitable for the determination
of total sediment in our
343° C+ (650° F+) boiling point product. The 343° C+
(650° F+) boiling point product can be
directly tested for total sediment which is designated as the "Existent IP
Sediment value." We
have found that the Existent IP Sediment Test gives essentially equivalent
test results as the
Shell Hot Filtration Solids Test described above.
2n As it is recommended that the IP 375/86 test method be restricted to
samples containing
less than or equal to about 0.4 to 0.5 wt % sediment, we reduce sample size
when high sediment
values are observed. This leads to fairly reproducible values for even those
samples with very
large sediment contents.
As the term is used herein a heavy hydrocarbon oil is a hydrocarbon oil
containing a
is substantial amount of components having a boiling point above about
565° C. (1050° F.). ,
Heavy hydrocarbon oils which may be utilized in the process of this invention
may include high
boiling petroleum cuts typified by gas oils, vacuum gas oils, coal/oil
mixtures, residual oils, ,
vacuum residue, and other similar refining residues that have a high
atmospheric boiling point.
An illustrative example of such a heavy hydrocarbon oiI is an Arabian
Medium/Heavy Vacuum
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Residue having the properties set forth in the first column of Table 1.
Another illustrative
example of a heavy hydrocarbon oil includes a mixture of a fluid cracked heavy
cycle gas oil
~ (FC HCGO) and an Arabian Medium/Ileavy Vacuum residue the properties of
which are given
in the second column of Table 1.
TABLE 1
Property I II
API Gravity 4.4 3.1
1000 F.+, vol % 87.3 76.1
1000 F.+, w % 88.3 -
1000 F.- w % 1 I .7 -
Sulfur, w % 5.8 5.6
Total Nitrogen, wppm 48I 5 4328
Hydrogen, w % 10.10 9.88
Carbon, w % 83.5 84.10
Alcor MCR, w % 22.4 20.2
Kinematic Viscosity, cSt
@ 200 F. 1706 -
@ 250 F. 476 -
Pour Point, F. 1 I O -
n-CS Insolubles, w % 35.6 30.16
n-C~ Insolubles, w % 10.97 9.49
Toluene insolubles, w % 0.01 O.OI
Asphaltenes, w % I0.96 9.48
Metals, w~nrn
Ni 44 37
V 141 118
Fe Il 9
Sediment, wppm Nil Nil
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As the term is used herein, a heavy whole petroleum crude oil is a dewatered
crude oil
containing a substantial amount of components having a boiling point above
about 565° C.
(1050° F.}. An example of heavy whole petroleum crude oil is Middle
Eastern heavy whole
s petroleum crude oil some of the properties of which are summarized in Table
2 and the
distillation data for which is given in Table 3.
Table 2
Property
API Gravity 14.4
Sulfur (w%) 6.17
Total Nitrogen (wppm) 2255
Pour Point ( C (F)) -25 {-14)
Viscosity (cst) @20 C. 2045.0
@40 C. 429.1
@ $0 C, 229.0
Neutralization Number (mg KOH/gm) 0.55
Microcarbon Residue (w%) 12.6
Vanadium (wppm) 68
Nickel (wppm) 29
Iron (wppm) 9
C6's and heavier (LV%) 99.82
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_7_
Table 3
' Fraction Boiling Range ( C (F))Weight
Light Hydrocarbons IBP to C4 0.1
Light Naptha iC5 to 82 (180) 0.2
Fntermediate Naptha 82 (180) to 130 (265) 0.9
Heavy Naptha I30 (265) to 177 (350)2.2
Light Kerosene 177 (350) to 218 (425)3.5
Heavy Kerosene 218 (425) to 260 (500)4.4
Atmospheric Gas Oil 260 (500) to 343 (650)11.5
Light Vacuum Gas Oil 343 (650) to 454 (850)18.4
Heavy Vacuum Gas Oil 454 (850) to 566 (1050)17.2
Vacuum Residue 566 (1050) and greater41.6
The process of this invention is also useful for the hydroconversion of other
refinery
residues and high boiling oils which contain a majority of components boiling
above 565° C.
s (1050° F.) thus converting them to hydrocarbon products boiling below
565° C. (1050° F.). In
such cases the reactor feed may be Bottoms Flash Drum liquids which have a
nominal 343° C+
(650° F+ boiling point, coal/oil mixtures, tar sand extracts, bottoms
from deasphalting
processes and other similar hydrocarbon mixtures having a boiling point of
above 343° C. (650°
F.). such liquids can be generally characterized as also having undesirably
high content of
io components boiling above 565° C. (1050° F.), sediment-
formers, a high content of metals, a
high sulfur content, carbon residue, and asphaltenes. Asphaltenes are herein
defined as the
quantity of n-heptane insolubles minus the quantity of toluene insolubles in
the feedstock or
product.
The present invention may be carried out in any hydroconversion zone suitable
for the
' is conditions of the improved hydroconversion reaction as is described
herein. For the purposes of
the present disclosure, a hydroconversion zone can be accomplished by either a
slurry technique
or by an expanded bed technique, also know as an ebullated bed technique. If
an ebullated bed
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_g_
technique is used, the hydroconversion zone may contain one or more reactors
which contain
expanded beds of supported heterogeneous catalyst. Generally in an ebullated
bed process, the
bed of supported catalyst is expanded and modified by upflow of the liquid
feed and hydro~Ten
containing feed gas in the reactor at space velocities effective to provide
adequate mobilizatiion
s and expansion of the catalyst. Thus contact between the catalyst and the
reactants is promoted
without substantial carry over of the supported catalyst into the product
stream. The bulk
density of the supported catalyst is a factor in the selection of the catalyst
from the stand point of
attaining appropriate bed expansion and mobilization at effective space
velocities. In practice of
the process of this invention, the catalyst, preferably in the form of
extruded cylinders of about
io 0.030 to 0.050 inch diameter and about 0.08 to 0.15 inch length may be
placed within a reactor
in an amount sufficient to occupy at least about 30% of the reactor void
volume. Catalyst is
typically withdrawn on a periodic basis and then replaced with new catalyst to
maintain t:he
proper amount of catalyst present and maintain constant catalyst activity in
the reactor. Specific
details of ebullated bed reactors should be known to one skilled in the art as
exemplified by LT.S.
is Patent Numbers 4,549,957; 3,188,286; 3,630,887; 2,987,465; and Re. 25,770.
The heterogeneous catalyst utilized in the process of the present invention is
disclosed in
detail in U.S. Patent Number 5,435,908 .
The catalyst support may be alumina, silica, alumino-silicates or any other
2o conventional heterogeneous catalyst support which should be known to one
skilled in the art.
As is disclosed therein, alumina is the preferred support and may be alpha,
beta, theta, or gamma
alumina, although it is preferred to use gamma alumina. The catalyst which may
be employed
should be selected and characterized based on the properties of Total Surface
Area (TSA), Total
Pore Volume (TPV), and Pore Diameter Distribution (Pore Size Distribution
PSD). The Total
zs Surface Area should be about 150-240, preferably about 165-210. The Total
Pore Volume
(TPV) may be about 0.70-0.98, preferably 0.75-0.9~.
The Pore Size Distribution (PSD) is such that the substrate contains primary
micropores
of diameter less than about 100 ~ in amount less than 0.20 cc/g and preferably
less than about
0.15 cc/g. Although it rnay be desired to decrease the volume of these primary
micropores to C
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-9-
cc/g, in practice its found that the advantages of this invention may be
attained when the volume
of the primary micropores is about 0.04-0.16 cc/g. This corresponds to less
than about 20% of
TPV, preferably less than about 18% of TPV. The advantages are particularly
attained at about
5-18% of TPV. It will be apparent that the figures stated for the % of TPV may
vary depending
s on the actual TPV (in terms of cc/g). Secondary micropores having diameters
in the range of
about 100 ~ - 200 t~ are present in amount as high as possible and at least
about 0.33 cc/g (34%
of TPV) and more preferably at least about 0.40 cc/g (50% of TPV). Although it
is desirablE; to
have the volume of secondary micropores as high as possible (up to about 74%)
of the TPV, it is
found that the advantages of this invention may be attained when the volume of
secondary
~o micropores is about 0.33-0.6 cc/g.
Pores having a diameter greater than 2001 are :considered macropores and
should be
present in amount of 0.18-0.45 cc/g (26-46% of TPV) while macropores having
diameters
greater than 10001 are preferably present in amount of about 0.1-0.32 cc/g (14-
33% of TPV) .
It will be apparent that the catalysts of this invention are essentially
bimodal: there is one
is major peak in the secondary micropore region of 100 ~-200 ~ and a second
lesser peak in 'the
macropore region of greater than or equal to 200 A.
The catalyst support which may be employed in practice of this invention is
available
commercially from catalyst suppliers or it may be prepared by variety of
processes typified by
that wherein about 85-90 parts of pseudobohmite silica-alumina is mixed with
about 10-15 parts
zo of recycled fines. Acids is added and the mixture is mulled and then
extruded in an Auger type
extruder through a die having cylindrical holes sized to yield a calcined
substrate of 0.03~t0.003
inch diameter. Extrudate is air-dried to a final temperature of typically
about 121° = 135° C.
(250°-275° F.) yielding extrudates with about 20-25% of ignited
solids. The air-dried extrudate
is then calcined in an indirect fired kiln for about 0.5 - 4 hours in an
atmosphere of air and steam
zs at typically about 538° - 621° C. (1000°-1150°
F.).
Generally the alumina support and the finished catalysts utilized in the
process of the
present invention should have the characteristics and properties set forth in
Table 4 wherein is
should be noted that:
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Column 1 lists the broad characteristics for the catalyst support including
Pore Volume
in cc/g and as % of TPV; Pore Volume occupied by pores falling in designated
ranges - as a v%
of Total Pore Volume TPV; and the Total Surface Area in m2/g. ,
Column 2 lists the broad range of characteristics for a First Type of catalyst
useful in the
s practice of this invention.
Column 3 lists the characteristics of a catalyst that is illustrative of a
preferred catalyst
used in the practice of the present invention.
Column 4 lists a broad range of characteristics for a Second Type of catalyst
found to be
useful in practice of the process of this invention.
TABLE 4
1 2 3 4
TPV (ccl~~~ 0.7-0.98 0.7-0.98 0.87 0.7-0.98
21000 t~ 0.1-0.32 0.1-0.22 0.16 0.15-0.32
X250 ~ 0.15-0.42 0.15-0.31 0.26 0.22-0.42
>200 A 0.18-0.45 0.18-0.34 0.29 0.24-0.45
__<100 ~ 0.2 max O.IS max 0.09 0.2 max
100-200 0.33 min 0.40 min 0.49 0.33 min
TP~%) 100 100 100 100
>_i000 ~ 14-33 14-22 18.4 22-33
X50 ~r 22-43 22-32 29.9 32-43
X200 ~ 26-46 26-35 33.4 35-46
>100 A 20 max l5max 10.3 20 max
100-200 A 34 min 50 min 56.3 34 min
Total Surface Area 150-240 155-240 199 150-210
(m2/g)
At least a portion of the surface of the catalyst support is covered with
metals or metal ,
oxides to yield a product catalyst containing a Group VIII non-noble oxide in
amount of 2.2 to 6
weight percent, and a Group VI-B metal oxide in amount of 7 to 24 weight
percent. The Group
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VIII metal may be a non-noble metal such as iron, cobalt, or nickel and
preferably is nickel. The
Group VI-B metal may be chromium, molybdenum, or tungsten and preferably is
molybdenum .
The catalysts utilized in the process of the preaPnt invention should contain
no more than
about 2 weight percent of P205 and preferably less than about 0.2 weight
percent. Phosphorus
s containing components should not be intentionally added during catalyst
preparation because the
presence of phosphorus undesirably contributes to sediment formation. Silica
SiOZ may be
incorporated in small amounts typically up to about 2.5 weight percent.
These catalyst metals may be loaded onto the alumina support by spraying the
support
with a solution containing the appropriate amounts of water soluble metal
compounds. 'The
~o Group VIII metal may be loaded onto the alumina typically from a 10 to 50
weight percent
aqueous solution of a suitable water-soluble salt such as nitrate, acetate,
oxalate and other
similarly suitable compounds The Group VI-B metal may be loaded onto the
alumina typically
from a 10 to 2~ weight percent aqueous solution of a water-soluble salt such
as ammonium
molybdate or other suitable molybdate salts. Small amounts of H202 may be
added to stabilize
~s the impregnating solution. It is preferred that solutions stabilized with
H3P04 not be used. in
order to avoid incorporating phosphorus into the catalyst. Loading of each
metal may be
effected by spraying the alumina support with the aqueous solution at
15° - 38° C. (60° -100° F.)
followed by draining, drying at 104° - 149° C. (220° -
300° F.) for 2-10 hours and calcining at
482° - 677° C. (900° - 1250° F.) for 0.5-5 hours.
.
2o The heterogeneous catalyst may be characterized by the content of metals or
metal
oxides deposited on the at least part of the catalyst support surface. Such
parameters are given
in Table 5. It should be noted that the column numbers utilized in this table
correspond to those
used above in Table 4.
TABLE 5
Metals (w%) 1 2 3 4
VIII 2.2-6 2.5-6 3.1 2.2-6
VIB 7-24 13-24 14 7-24
SiOz <2.5 <2.5 2 <2
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peps c2 <2 <0.2 <2
In the general practice of the process of this invention, a suitable amount of
the
heterogeneous catalyst is placed within a reactor. The feed mixture is
admitted to the lower
portion of the reactor which is maintained at a temperature of about
343° - 454° C. (650° - 850°
s F.), preferably about 371 ° C. (700° F.) to about 441 °
C. (825° F.). The total pressure of the
reactor may be from about 6996 kPa (1000 psig) to about 24,233 kPa (3500 psig)
but preferably
it is maintained from about 9065 kPa (1300 psig) to about 11,822 kPa (1700
psig). The
hydrogen containing feed gas is often admitted mixed with the hydrocarbon
charge. Typically
the hydrogen containing feed gas is introduced at a rate from about 356.2
liters (H2) / Iiters(oil)
io (2000 standard cubic feet (H2) l Barrel (oil)) to about 1781.2 liters (H~ l
liters(oil) (10,000
standard cubic feet (H2) / Barrel {oil)) and preferably from about 356.2
liters (H2) / Iiters(oil}
(2000 standard cubic feet (H~ / Barrel (oil)) to about 712.5 liters (H2) /
liters(oil) (4,000
standard cubic feet {H2) / Barrel {oil)). In an ebullated bed reactor, the
flow of the reaction feed
mixture through the bed should be conducted at a rate from about 0.08 to 1.5
m3 (oil) / m3
is (reactor void volume)/hour and preferably from about 0.1 to 1.0 m3 (oil) /
m3 (reactor void
volume)/hour. During operation, the bed expands to form an ebuliated bed with
a defined upper
level. The passage of the hydrocarbon feedstock through the ebullated bed
reactor converts at
least a portion of the higher boiling point hydrocarbons to Iower boiling
products by the
hydroconversionlhydrocracking reaction. Recovery of the product hydrocarbon
oiI which
2o includes a substantial portion of components having a boiling point below
about 565° C. (1050°
F.) is effected by conventional means from the portion of the reactor above
the upper level of the
ebullated bed so that heterogeneous catalyst is not removed. further
conventional means such as
passage through a hot separator, cold separator, pressure flash drums,
atmospheric and vacuum
fractionators and other conventional means allows for the separation of the
different fraction of
is the product stream. In one embodiment, the highest boil fractions of the
product stream are
directed back through the hydroconversion zone as part of the hydrocarbon
feed. Thus by
"recycling" the higher boiling point fractions of the product back into the
reaction a minimal
amount of reactor waste is generated. Operation of the hydroconversion zone is
essentially
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isothermal with a typical maximum temperature difference between the inlet and
the outlet of
about 0° to 27° C. (0°-50° F.), preferably from
about 0° to 16° C. (0°-30° F.).
It has been unexpectedly and surprisingly found that the inclusion of a Group
VI-B metal
compound in the heavy hydrocarbon oil feed achieves a stable hydroconversion
reaction at total
s pressures below 13,200 kPa (1900 psig). As previously noted, prior to the
present invention,
hydroconversion or hydrocracking reactions carried out under such conditions
become
unpredictable and unstable due to the accumulation of deposits and sediments
in the reactor and
the relevant process systems. In contrast it has been found that the content
of such deposits and
sediments are substantially reduced in the practice of the present invention.
The Group VI-B
~o metal compound should be selected so that the first decomposition
temperature that is at least
222° C (431 ° F.). This is substantially greater than the first
decompositions temperature of other
molybdenum compounds utilized in the prior art such as molybdenum naphthalate
(166°C
(331 °F)) or molybdenum octoate (111 ° C (231 ° F)). In
addition, the compound should be
soluble in the heavy hydrocarbon oil feed utilized in the hydroconversion
reaction.
is In one embodiment of the present invention the Group VI-B metal compound is
mixed
with the heavy hydrocarbon oil to give a mixture having from about 0.005 to
about 0.050 weight
percent metal compound present in the hydroconversion reactor feed mixture.
When calculated
based on the amount of elemental metal, these concentrations of metal compound
correspond to
values of 0.001 to about 0.004 weight percent metal.
2o In another related embodiment the Group VI-B metal is dissolved in a
portion of the
heavy hydrocarbon oil to give a pre-feed mixture in which the concentration of
metal compound
is from about 0.02 to about 0.42 weight percent which corresponds to a
concentration of about
0.004 to 0.03 of metal when calculated based on the amount of elemental metal
present. This
pre-feed mixture is mixed with additional hydrocarbon oil to give the final
reactor feed of the
is heavy hydrocarbon oil and the Group VI-B metal compound having from about
0.005 to about
0.050 weight percent metal compound present which when calculated based on the
amount of
elemental metal, correspond to values of 0.001 to about 0.004 weight percent
metal.
In yet another embodiment the Group VI-B metal compound is an oil soluble
molybdenum compound. The oil soluble molybdenum compound is mixed with the
heavy
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hydrocarbon oil to give a mixture having from about 0.005 to about 0.050
weight percent metal
compound present in the hydroconversion reactor feed. These concentrations of
metal compound
correspond to values of 0.001 to about 0.004 weight percent when calculated
based on elemental
molybdenum. A commercially available molybdenum compound that has been found
to be
s especially useful in the practice of the present invention is molybdenum LIN-
ALL(TM) which is
a proprietary mixture including the reaction products of molybdenum with tall
oil fatty acids
available from OMG Americas, Inc. of Cleveland, Ohio USA.
Therefore in view of the above, one aspect of the present invention is a
process of
catalytic hydroconversion of a heavy hydrocarbon oil containing a substantial
portion of
~o components having an atmospheric boiling point above about 565° C.
(1050° F.) to give a
product hydrocarbon oil containing a substantial portion of components having
a boiling point
below about 565° C_ (1050° F.). The process includes mixing the
heavy hydrocarbon oil with an
oil soluble molybdenum compound, to give a mixture having from about 0.005 to
about 0.050
weight percent molybdenum compound. In one embodiment this may be achieved by
mixing a
is first portion of the heavy hydrocarbon oil with the soluble molybdenum
compound to give a pre-
feed mixture in which the concentration of molybdenum compound is from about
0.02 to about
0.42 weight percent, and mixing the pre-feed mixture with additional heavy
hydrocarbon oil to
give a reactor feed mixture having a concentration of molybdenum compound from
about 0.005
to about 0.050 weight percent. The molybdenum compound is selected so that it
has a first
zo decomposition temperature of at Ieast 222° C. (431 ° F.). The
mixture of heavy hydrocarbon oil
and molybdenum compound is introduced into a hydroconversion zone having a
temperature
from about 343° C. (650° F.) to about 454° C.
(850° F.) and a total pressure from about 6996
kPa (1000 psig) to about 24,233 kPa (3500 psig). The hydroconversion zone
should contain a
heterogeneous catalyst which includes a Group VIII non-noble metal oxide, a
Group VI-B metal
is oxide and no more than 2 weight percent phosphorous oxide supported on an
alumina or silica-
alumina support. In a sub-embodiment the Group VIII non-noble metal oxide is
nickel and the
Group VI-B metal oxide is molybdenum. In another sub-embodiment the catalyst
support is ,
alumina which has a Total Surface Area from about 150 to 240 m2/g, a Total
Pore Volume
(TPV) from 0.7 to 0.98 and a pore diameter distribution such that no more than
20% of the TPV
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is present as primary micropores having diameters no greater than 100 ~, at
least about 34% of
the TPV is present as secondary micropores having diameters from about 100 to
200 ~, and
from about 26% to 46% of the TPV is present as macropores having diameters of
at least 200 ~.
Also being introduced into the hydroconversion zone is a reactor feed gas
which includes a
s majority of hydrogen gas, preferably at least 93% by volume of hydrogen and
which is
substantially free of hydrogen sulfide. The hydrogen containing feed gas is
introduced at a rate
from 356.2 liters (H2) / liters(oil) (2000 standard cubic- feet (H2) / Barrel
(oil)) to about 1781.2
liters (H2) l liters(oil) (10,000 standard cubic feet (H2) / Barrel (oil)). In
one sub embodiment of
this aspect of the present invention the temperature of the hydroconversion
zone is from about
~0 371° C. (700° F.) to about 441° C. (825° F.)
and the total pressure is from about 9065 kPa (1300
psig) to about 11,822 kPa (1700 psig). When the hydroconversion zone is an
ebullated bed
reactor, the introduction of the feed mixture into the hydroconversion zone is
conducted at a rate
from about 0.08 to 1.5 rn3 (oil) / m3 (reactor void volurne)/hour. During the
practice of any of the
above noted aspects of the invention the product hydrocarbon oil is recovered
by conventional
Fs means from the hydroconversion zone. The recovered product hydrocarbon oil
has an API
gravity uplift of greater than 10 over the API gravity of the heavy
hydrocarbon oil feed sediment
content. Of particular note, the sediment content of the product fraction that
has a boiling point
higher that 343° C. (650° F.) is substantially reduced when
compared to the same product
fraction resulting from the practice of the process in the absence of the
molybdenum compound.
zo in particular sediment values achieved are below 1 weight percent and
preferably below 0.7
weight percent.
Another aspect of the present invention is a method of hydrocracking a heavy
whole
petroleum crude oil having at Ieast 40 weight percent components boiling above
about 565° C.
(1050° F.) to give a processed crude oil containing a majority of
components boiling below
2s about 565° C. (1050° F.). The method of this aspect comprises
mixing the heavy whole
petroleum crude with a oil soluble Group VI-B metal compound having a first
decomposition
~ temperature of at least 222° C. (431 ° F'.), to give a reactor
feed mixture having from about 0.005
to about 0.050 weight percent metal compound; reacting the reactor feed
mixture and a
hydrogen containing feed gas in an ebullated-bed reactor, and recovering the
product processed
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crude oil by conventional means. In this aspect the reactor is at a
temperature from about 343°
C. (650° F.) to about 454° C. (850° F.) and at a total
pressure of no greater than about 13,201
kPa (1900 psig). The ebullated bed includes a supported heterogeneous
catalyst, the supported
heterogeneous catalyst comprising a Group VIII non-noble metal oxide, a Group
VI-B metal
s oxide, no more than 2 weight percent phosphorous oxide and an alumina or
silica-alumina
support. One facet of the present aspect is that the alumina or silica-alumina
support is selected
so that the resultant meals bearing catalyst has a Total Surface Area (TSA) of
about 1 SO to 240
m2/g, and Total Pore Volume (TPV) from about 0.7 to 0.98 and a pore diameter
distribution
such that no more than 20% of the TPV is present as primary micropores having
diameters no
lo greater than 100 1~, at least about 34 % of the TPV is present as secondary
micropores having
diameters from about 100 to about 200, and from about 26% to about 46% of the
TPV is
present as macropores having diameters of at least 200 ~. Within another facet
of this aspect of
the present invention the Group VI-B metal compound in the reactor feed
mixture is a
molybdenum compound may be either mixed directly into the feed mixture or made
by
is combining a first portion of the heavy whole petroleum crude oiI with the
oil soluble
molybdenum compound to give a pre-feed mixture in which the concentration of
molybdenum
compound is from about 0.020 to about 0.420 weight percent, and mixing the pre-
feed mixture
with additional heavy whole petroleum crude oil to give a reactor feed mixture
having a
concentration of molybdenum compound from about 0.005 to about 0.050 weight
percent. The
2o recovered processed crude oil resulting from the practice of the present
aspect of the invention
has an API gravity uplift of greater than 10 over the API gravity of the heavy
whole petroleum
crude oil. In addition the processed crude oil has a decreased amount of
sediment in the portion
of the processed heavy crude oil having a boiling point above about
343° C. (650° F.) as
compared with the same product resulting from the process conducted without
the molybdenum
2s compound in the reactor feed mixture.
The following examples are included to demonstrate preferred embodiments of
the
invention. It should be appreciated by those of skill in the art that the
techniques disclosed in
the examples which follow represent techniques discovered by the inventors to
function well in
the practice of the invention, and thus can be considered to constitute
preferred modes for its
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practice. However, those of skill in the art should, in light of the present
disclosure, appreciate
that many changes can be made in the specific embodiments which are disclosed
and still obtain
- a like or similar result without departing from the scope of the invention.
In the following examples the heavy hydrocarbon oil feedstock was a Mid-
Eastern
s Heavy Whole Crude oil straight out of the ground with no other treatment
except dewatering,
before introduction to the process of the instant invention. Properties of the
Mid-Eastern Heavy
Whole crude oil are given above in Tables 2 and 3.
Example 1. An ebullated bed pilot unit was charged with heterogeneous catalyst
having
the properties of Column 3 in Tables 4 and 5. The heavy hydrocarbon oil feed
was admitted in
lo the liquid phase at 2515 psig to the ebullated bed pilot unit with an
overall liquid space velocity
(LHSV) of 0.54 per hour and an overall average temperature of 415° C
(780° F) to maintain the
reactor conditions. Hydrogen containing feed gas containing at least 93% by
volume hydrogen
and substantially free of hydrogen sulfide is mixed with the oil feed in an
amount of 623 liters
(HZ) / Iiters(oil) (3500 standard cubic feet(gas) / barrel (oil)). During the
course of the
~ s experiment the hydroconversion zone of the ebullated bed pilot unit was
maintained at a
temperature of about 415° C. (780° F.}. The through-put ratio
for the reaction was about 1Ø
The through-put ratio is defined as the ratio of the volumetric reactor feed
rate, including
recycle, to the volumetric fresh feed rate The total pressure of the
hydroconversion zone was
decreased until the reaction became unstable.
ao A sample of the results are given in below in Table 6 along with the
properties of the
reaction product from each pilot run. It should be noted that the values for
each run were taken
approximately seven days after the change in total pressure so as to allow the
reaction to
stabilize. The values for run 3419 are given in brackets because the run at
1700 psig were
unstable after the seven day stabilization period. With regard to Table 6 it
should be noted that:
as the values for the change in the API gravity are relative to the API
gravity of the hydrocarbon oil
feed; the value for conversion is the percent decrease in the volume of the
fraction boiling above
538° C. (1000° F.} of the hydrocarbon feed; the abbreviation BFD
refers to the Bottoms Flash
Drum fraction of the product hydrocarbon which has a nominal boiling point of
greater than
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343° C (6S0° F.) and TLP refers to the Total Liquid Product
recovered from the
hydroconversion zone.
Table 6
Run No. 3407 3411 3413 3416 3419
Total Pressure, kPa 17,338 1S,9S9 14,378 13,201 [11,822]
(prig) (2500) (2300) (2100) (1900) [(1700)]
Inlet H2 Partial Pressure2325 2139 1953 1767 [1S8I]
(psig)
Metered HZ Consumption,183 167 1S8 I36 -------
1 (H2) / 1 (oil) (SCF/Bbl)(1030) (939) (887) (76S) -------
Properties of Product
Change in APi gravity +12.5 +I2.1 +11.8 +10.7 -------
Conversion (vol %) 56.8 57.8 54.9 S3.S -------
BFD sediment (wt %) 0.13 0.21 0.16 0.23 [1.46]
TLP sediment (wt%) 0.66 0.93 0.86 1.7S [ 1.61
s Given the above data, one of ordinary skill in the art should notice that as
the pressure of
the reaction decreases, the amount of sediment present in both the BFD
fraction and the TLP
increases. This increase in sediment is believed to be due to the incomplete
conversion of large
molecular weight hydrocarbons present in the hydrocarbon feed. One skilled in
the art should
also appreciate that the sediment values of run 3419 are substantially higher
than is typically
lo considered acceptable in the practice of the hydroconversion process which
are typically below
1.0 weight percent and preferably below 0.7 weight percent.
The instability of the hydroconversion reaction at 1700 psig total pressure,
as noted
above for run 3417 is further supported by the data shown below in Table 7
which gives a '
detailed look at the sedimentation problem encountered. With reference to
Table 7 it should be
l s noted that the values given are for reactions that have "lined-out" that
is to say the parameters
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have become stable. It should further be noted that: VBR means Vacuum Bottoms
Recycle
which is a process in which the fraction of the product stream that has a boil
point greater than
a about 538° C (1000° F) is reintroduced into the
hydroconversion zone as a portion of the
hydrocarbon feed. This technique is conventionally used to reduce the sediment
content of the
s hydrocarbon product.
Table 7
Run No. 3420 3424 3426
VBR Yes Yes No
BFD Sediment0.18 2.4 4.I
(Wt %)
TLP Sediment1.55 1.57 ---
(vVt%)
In view of the above, one skilled in the art should appreciate that the level
of sediment
rapidly increases when the hydroconversion zone is operated at a total
pressure of / 1,822
io kPa(I700 psig). The use of vacuum bottoms recycling did not reduce the
sediment content
under these hydroconversion conditions. Once VBR was stopped the sediment
content rapidly
reached unacceptably high levels which is considered an unstable condition.
Example 2. In this example the ebullated bed reactor utilized above in Example
I was
used. Molybdenum LIN-ALL(TM) available from OMG Americas, Inc. of Cleveland
Ohio
is USA was mixed and introduced into the hydroconversion zone via the purge
oil system through
the catalyst withdrawal tube. The concentration of the molybdenum compound was
about 1500
parts per million by weight of the purge oil which corresponds to
approximately 220 parts per
million by weight of metal. The purge oil stream was heated to about 200 -250
° F. just prior to
injection into the hydroconversion zone. The purge oil stream represent 13.6%
of the fresh feed
2o going to the unit. As noted in Table 8 below, this is considered injection
method A. A sample of
the properties of the reaction product are given in below in Table 8. It
should be noted that the
values for each run were taken approximately seven days after the first
introduction of
molybdenum compound so as to allow the reaction to stabilize.
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Table 8
Run No. 3429 3432 3435
Injection Method A B B
Total Pressure, kPa 11,822
(psig) (1700) (1500) (1300)
Inlet HZ Partial Pressure 2325 2139 1953
~sig)
Metered H2 Consumption,183 167 158
1 (Hz) / 1 (oil) (1030) (939) (88?)
(SCFBbI)
Properties of Product
Change in API gravity+10.8 +10.6 +10.2
Conversion (vol %) 49.6 50.3 53.5
BFD sediment (wt 0.29 0.37 0.56
%)
TLP sediment (wt%) 0.63 n/a 1.28
In view of the above results one of ordinary skill in the art should
appreciate that the
introduction of the molybdenum compound into the hydroconversion zone
substantially reduces
s the sediment content of the hydrocarbon product stream. It should be
appreciated by one of skill
in the art that the sediment values of the product stream have a direct effect
on the long term
operation of the hydroconversion reactor. As previously noted high BFD
sediment values (i.e.
above about 1.0 wt%) are undesirable.
Exam~ie 3. In this example the ebullated bed reactor utilized above in Example
2 was
~o used. Molybdenum LIN-ALL(TM) available from OMG Americas, Inc. of Cleveland
Ohio
USA was mixed introduced into the hydroconversion zone along with the
hydrocarbon feed. the
mixture of the hydrocarbon feed and the molybdenum compound was carried out
through he
flush oil pump in the fresh feed system. The concentration of molybdenum LIN-
ALL was
approximately 902 parts per million by weight which corresponds to 132 parts
per million metal.
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This stream represented 22.7% of the fresh feed into the reactor The
hydrocarbon feed was
a
mixed with the hydrogen feed gas and passed through the feed heater where the
combined feed
was heated to about 11 ° C. (20° F.) above the reactor
temperature. The residence time of the
combined feed in the feed heater is estimated to be approximately 52 seconds
at a the total
s reactor pressure of 11,822 kPa (1700 psig) and about 40 seconds at about
1300 psig. The heated
combined feed was then introduced into the hydroconversion zone of the
reactor. As noted in
Table 8 above, this method of introduction of the molybdenum LIN-ALL (TM) is
considered
injection method B. A sample of the properties of the reaction product are
given in above in
Table 8. It should be noted that the values for the run were taken
approximately seven days after
lo the first introduction of molybdenum compound so as to allow the reaction
to stabilize. In
particular the present invention allows for the operation of hydroconversion
at pressures less
than 1700 psig and as shown above as low as 1300 psig. This is in contrast to
conventional
conditions which are typically 2500 psig or greater.
While the compositions and methods of this invention have been described in
terms of
is preferred embodiments, it will be apparent to those of skill in the art
that variations may be
applied to the process described herein without departing from the concept,
spirit and scope of
the invention. Other advantages of the present invention will be realized in
the practice of the
present invention and appreciated by one of skill in the art. All such similar
substitutions and
modifications apparent to those skilled in the art are deemed to be within the
spirit, scope and
2o concept of the invention as it is set out in the following claims.
