Note: Descriptions are shown in the official language in which they were submitted.
12177S6 ~-1326
DEMETALLIZATION CATALYST AND PROCESS FOR
METALS-CONTAINING HYDROCARBON FEEDSTOCKS
BACKGROUND OF INVENTION
: . ,
This invention pertains to an improved synthetic demetal- l ¦
lization catalyst material containing substantially porous alumi~
num oxide promoted with 0.5-10 W ~ active metal and to
a process using the catalyst for demetallization and hydroconver-
sion of metals-containing hydrocarbon feedstocks to produce lower
boiling hydrocarbon products.
Bauxite is a naturally-occurring low-cost aluminum oxide
material which when promoted with certain metal oxides is rela-
tively effective as a catalyst in upgrading heavy metals-containing
petroleum feedstocks in an ebullated-bed reactor, provided that the~
catalyst has suitable fluidization patterns in the reactor. The
metal compounds need to be substantially removed from such petro-
leum crudes or residua fractions to provide suitable feed materials
for further processing such as catalytic cracking and/or desulfur- - ¦
ization. For example, U.S. Patents 3,901,792 and 3,965,665 to
Wolk, et al, disclose a two-stage catalytic reaction process for
demetallization and conversion of high-metals content petroleum
residua, in which the first stage contains a promoted bauxite con-
tact material which has a primary purpose of removing the vanadium ,
and nickel compounds from the hydrocarbon feedstock materials. The
treatment of the feedstock in the first stage reactor was found
to improve the operation of the second stage reactor significantly,
and resulted in reduced processing costs for the hydrodesulfuriza-
tion operation in the second stage reactor.
12~7756
In a co-pending patent application, a method is disclosed
~or effectively pre-treating the activated promoted bauxite
material to achieve more satisfactory operations in an ebullated
bed demetallization and hydroconversion process. However, the
naturally-occurring bauxite material usually has substantial
variations in its chemical composition and in particle size
distribution, because these properties are dependent on the geo-
graphical location of the mines and formations from which the
bauxite is obtained.
Because of these problems with the available naturally-
occurring promoted activated bauxite demetallization catalysts and the
substantial expense of available combination catalysts when used
for demetallization operations, a need exists for further improve~
ments in such demetallization catalysts. A synthetic spherical-
shaped demetallization catalyst has been developed for use in
ebullated-bed demetallization processes to provide effective and ~,
economical processing of high-metals containing residua, such as
those from California, Mexican, and Venezuelan petroleum crudes.
This low-cost synthetic catalyst has strong attrition resistance
characteristics and provides for effective demetallization opera-
tions and provides an alternative to promoted activated bauxite
~catalyst for demetallization of such high-metals content feedstocks.
. .
SUMMARY OF INVENTION o
This invention provides a synthetic catalyst material
which is particularly useful for demetallization of metals-contain-
ing petroleum residua feedstocks. The catalyst comprises particles
of substantially aluminum oxide promoted with metal oxides selected
from the group consisting of chromium, iron, molybdenum,
titanium, and tungsten and having a total metals content of about
1` lZ~7756
0.5-lO W ~, said catalyst having a total pore volume of abaut 0.350 to about
0.500 cc/gm, said catalyst particles within the 3% and 97% percentiles of all
particles having an equivalent diameter ratio of larger to smaller particles
with~ a range of about 1.~ to 2Ø ~ore specifically, the narrow particle
I differential size range is such that the ratio of particle equivalent diameter
(based on volume/surface area ratio or the particles) at 97 W % under size to
¦ that at 3 W % under size does not excee~ about 2.0, and preferably is within
a ratio range of 1.2-2Ø Also, the catalyst materia~ preferably contains
I about 0.6-3.0 W % rnolybdenum promoter, has a surface area of 150-300 square
Il meters/gm, and the catalyst particles are preferably within a naminal size
jl range o, 12-18 mesh (~.~. Sieve Series). me catalyst particles are preferably
, substantially spherical shaped for providing increased structural and crush
strength and the uniformity of particle shape and size provide good fluidiza-
tion characteristics.
The demetallization catalyst of this invention is particularly advantag-
eous compared to catalysts previously used for demetallization operations on
¦ high metals-containing hydrocarbon feedstocks such as petroleum residua. L`abt
~1 oratory tests have demonstrated that this catalyst can typically remove 40-65
¦I W % of the feed metals, and achieve 50-60 V % conversion of 975F+ material
in a one-stage, catalytic single pass operation.
The present invention provides a process for hydrodemetallization and
i hydroconversion of hydrocarbon feedstocks containing at least about 200 ppm
¦ total metals, which process uses the synthetic particulate catalyst material
¦~ containing substantially pronoted aluminum oxide as described above. me pro-
cess ccmprises introducing a metals-containing hydrocarbon feedstock together
with hydrogen-rich gas into an ebullated bed catalytic reaction zone contain- !
, ing particulate aluminum oxide catalyst prcmoted with metal oxides selected
fram the group consisting of chramium, iron, molybdenum, titanium and tungsten
for hydrodemetallization reactions, said catalyst having a total metals content
,l of about 0.5-10 W % and a total pore volume of 0.350-0.500 cc/gm, said catalyst~
.! particles within the 3-37 percentile of all particles having an equivalent
within the 3-97 percentile of all particles having an equivalent diameter
,' ratio of larger to smaller particles not e~ceedin~ about 2.0; maintaining said
reaction zone at 780-850F temperature and 1000-3000 psig hydrogen partial
I pressure conditions, and catalytically hydrcd~l~tallizillg an~ hydl^ocon~rerl- ing the ,eedstock to produce `nydrocarbon qases and loweî boiling
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12~775~
hydrocarbon fractions; withdrawin~ said hydrocarbon gas and liquid
fractions from the reaction zone, and separating the hydrocarbon
fractions to produce lower boiling hydrocarbon liquid productsr
This demetallization and hydroconversion process for
metals-containing petroleum feedstocks and for which an attrition-
`resistant low cost catalyst material is needed advantageouslyuses this newly developed catalyst. The catalyst provides for ,'
;improved stable and sustained ebullated bed demetallization opera~ !
tions on high metals-containing feedstocks so as to achieve
60-80 W % removal of nickel and vanadium combined along with
50-70 V % conversion of the 975F+ fraction to produce lower boil- ',
ing hydrocarbon products in a single stage process. '
This synthetic catalyst can be advantageously used in
either a single stage ebullated bed demetallization process or in
the first stage ebullated bed reactor of a two-stage demetalliza- ~
tion and desulfurization process. The catalyst is preferably used .
in the first stage of a two-stage hydrodemetallization, hydro-
desulfurization and hydroconversion process.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a graph showing comparative fluidization
characteristics of the synthetic spherical catalyst material in an
ebullated bed reactor.
FIG. 2 is a schematic diagram showing a typical process for
catalytic hydro~emetallizationof hydrocarbon feedstocks in which the
synthetic catalyst is advantageously used according to the inven-
tion.
12~7756
DESCRIPTION OF INVENTION
According to the present invention, the newly-developed
synthetic demetallization catalyst has properties which are
selected to be particularly advantageous for demetallization opera-
~tions on petroleum feedstocks containing high concentrations of
;metals compounds. Important characteristics of the catalyst in- '
c~ude: i
. (a) good removal of vanadium and nickel compounds from
processed hydrocarbon feedstocks;
~b) generally spherical shape particles to provide
improved crush strength and attrition resistance;
(c) good fluidization patterns in ebullated bed reactor;
(d) low catalyst cOsts.
Properties of the catalyst material are provided in the ~.
following Table I.
TABLE I
Chemical and Physical Properties
- Aluminum Oxide, W ~ ~9o
~olybdenum, W % 0.5-3.0
Compacted Bulk Density,
gm/cc 0.8-1.0
Surface Area, M /gm 100-300
Pore Volume, cc/gm 0.35-0.50
(Determined by Hg Penetra-
tion Method, 60,000 psi)
Pore Size Distribution cc/gm
30 A Diameter 0.30-0.50
250 A Diameter 0.19-0.25
500 A Diameter 0.17-0.23
1500 A Diameter 0.15-0.20
4000 A Diameter 0.02-0.15
~Z177~;
TABLE I (Cont'd.)
Particle Size and Distribution
Nominal Paxticle Size
(U.S. Sieve Series) 12 mesh x 18 mesh
Median Particle Size (50 W %) 1.27 + 0.13 mm
97 W % (minimum) of catalyst
particles ~ 12 mesh (1.67 mm)
3 W ~ (maximum of catalyst ,
particles ~ 18 mesh (l mm)
Particle diameter ratio for
, 12 mesh/18 mesh particles 1.68
.. ;
Because the new synthetic demetallization catalyst of the pre-
sent invention is a manufactured product instead of a naturally-
occurring bauxite material activated and prcmoted with metal oxides, undesired ,
variations in the catalyst properties and particle size distribu-
tion are advantageously minimized. The pore volume is maintained
at least about 0.35 cc/gm and is preferably about 0.40-0.50 cc/gm,
which is appreciably larger than for the activated bauxite material~
and particularly has a greater percentage of the pores in diameters,
larger than about lO00 A than for activated bauxite. In addition,
the synthetic demetallization catalyst material has higher attri-
~ ~tion resistance and other advantages compared to the previously
used promoted bauxite material, as listed below:
. .
. .
Promoted Activated Synthetic
Bauxite Catalyst Catalyst
Particle Size Distribution Variable Within Definitive With-
Wide Range, Can in Narrcw Range
screen for desired
narrow particle size
ranges.
Particle Shape Irregular, with Spherical
sharp corners
Attrition Loss (~30 mesh)* 10-15 W % for 0.1-0.4 W ~ for
20 x 30l~esh Size 12 x l~esh Size
*Based on 7 hour attrition test in rotating drum.
`' ~Z~7756 ll
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!l 3ecause of the substantially spherical shape of the
catalyst particles, they are appreciably stronger and exhibit
significantly less attrition than do the naturally-occurring
~,lbauxite catalyst particles. In comparison with pre~reated bauxite¦
Ijcatalyst particles, it is noted tha' the attrition for the syn-
¦i thetic catalyst material is less tran about 4% of that for the
Ibauxite. Furthermore, the cost of the new synthetic catalyst is
¦,appreciably less than for other known demetallization catalysts.
¦~ The catalyst particles of the present invention may be
jlformed of known substrate materials such as a porous alumina.
¦¦Although such alumina should be substantially pure, it may con- l
¦Itain minor amounts of other metal oxides that are inert under the ¦
¦Iconditions of use. Other support materials such as silica-alumina
¦land catalytically active clays may also be used.
¦l A variety of procedures can be employed for preparing the
alumina support particles. In general, the smaller pores are
associated with alumina base materials. The larger pores can be
Il formed by known techni~ues ~7hich cculd employ pore growth pro- !
limoters. Catalyst pore growth promotion can be accomplished by
¦Iheating the material in the presence of a oas or ~etal compound,
stea~ing at elevated temperatures and treating with hydrogen at
¦~elevated temperatures. In another procedure, the larger pores czn,
j'be produced during preparation ~f the base material by use of a
~strong mineral or organic acid for leaching.
i
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!
,,
., .
. ...
~2~75~
A number of different catalytically active metals can be
deposited on the surface of the alumina substrate material of the
present catalyst. One preferred catalyst material uses molybdenum
in the form of Mo03. When molybdenum is used alone as a promoter
material, it provides good demetallization performance. Other ;
known metal oxides may be employed as promoters for the active
metal, for example, oxides of cobalt and nickel can be beneficial-
ly employed in c~mbination with molybdenum for superior demetalli-
~
zation. A preferred catalyst c~ntains between about 0.5 and S
10 W ~ molybdenum in the form of MoO3.
-
A ~eneral disclosure of tèchniques for catalyst formation
is found in an article by Higginson, G.W., Chemical Engineering,
Sept. 30, 1974. A more detailed disclosure of suitable catalyst
forming techniques is found in Long ~t al ~.S. Patent ~o.3,989,645'
Also, additional general information regarding preparation of~
catalysts may be found in "Heterogeneous Catalysis In Practice"
by C.M. Satterfield, published by McGraw-Hill Co., 1580, Chap. 4
p. 68-97.
The particle size of the catalyst support substrate should
be small enough to provide the desired contact area and be
readily ebullated in a reactor bed,as in the'H-Oil'process.
Laboratory fluidization tests comparison results per FIG. 2
showed that the bed expansion characteristics of the new synthetic
demetallization catalyst are similar to the conventional catalysts
widely used in the'H-Oil'process. This new spherical-
shaped synthetic catalyst has excellent fluid dynamics qualities
and provides smooth and uniform fluidization patterns in the
catalyst bed, and minimum catalyst carryo~er fr~m the ebullated
bed reactor. The synthetic spherical catalyst of the present in-
* Trademark
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vention is a preferred al~tive to promoted bauxite catalystfor demetallization o~erations on metals-containing feedstocks.
This new spherical-shaped catalyst material is advantageous-
ly used in a demetallization process for a high metals-containing
hydrocarbon feedstocks containing at least about 200 ppm total
; metals Gnd preferably containing 400-1500 ppm total metals. As
generally shown in FIG. 2, the catalyst is introduced into re-
actor 20 to provide ebullated catalyst bed 22 therein. A petro-
leum residuum feedstock containing metal compounds including vana-
dium and nickel is preheated along with a hydrogen~rich gas stream
i and introduced into the lower end of reactor 20. If desired,
reactor 20 can be the first stage of a two-stage process for
demetallization of the feed in a first stage reactor, followed by ,
hydrode ~ furization reactions in a second stage reactor using a high
activity desulfurization catalyst. '
The metals-containing petroleum feedstock at 10, containing
at least about 200 ppm total metals, such as Cold Lake and
Lloydminster bottoms from Canada or Bachaquero and Orinoco residua
from Venezuela, is pressurized at 12 and passed through preheater
14 for heating to at least about 500F. The heated feedstream at
15 is introduced into upflow ebullated bed catalytic reactor 20.
Heated hydrogen is provided at 16, and is also introduced into
reactor 20. This reactor is typical of that described in U.S.
Patent No. ~e.2~,77b, wherein a liquid phase reaction is accomp-
lished in the presence of a reactant gas and a particulate
catalyst such that the catalyst bed 22 is expanded. The reactor
contains a flow distributor and catalyst support plate 21, so that
the feed liquid and gas passing upwardly through the reactor 20
will expand the catalyst bed by at least about 10% over its
settled height, and place the catalyst in random motion in the
liquid.
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~21~i6
The synthetic catalyst particles in ebullated bed ~2 will
ha~e a relatively narrow s~ze range fox uniform bed expansion
under controlled liquid and gas flow conditions. While the usefuL
catalyst size range is between 12 and 20 mesh (U.S. Sieve Series)
with an upflow liquid velocity between about 1.5 and 10 cubic feet,
per minute per square foot of reactor cross-section area~ the `~
catalyst size is preferably particles of 12-18 mesh size. In the
reactor, the density of the catalyst particles, the liquid upward
flow rate, and the lifting effect of the upflowing hydrogen gas
are important factors in the expansion of the catalyst bed. By
control of the catalyst particle size and density and the liquid
and gas upflowing velocities and taking into account the viscosit~
of the liquid at the operating conditions, the catalyst bed 22 is ',
expanded to have an upper level of interface in the liquid as
indicated at 22a. The catalyst bed expansion should be at least
about 10% and is seldom more than about 80% of the bed settled-
or static height.
The proper ebullation of the catalyst in bed 22 in reactor
20 is greatly facilitated by use of a proper size catalyst. The -
synthetic catalyst used is added daily directly into the reactor
20 through suitable inlet connection means 25 at a rate between
aboùt 0.3 and l.0 lbs catalyst/barrel feed, and used catalyst is
withdrawn daily through suitable draw-off means 26.
Recycle of reactor liquid from above the solids interface
22a to below the flow distributor 21 is usually desirable to
establish a sufficient upflow liquid velocity to maintain the
catalyst in random motion in the liquid and to facilitate com-
pleteness of the hydrogenation reactions. Such liquid recycle is
preferably accomplished by the use of a central downcomer conduit
18 which extends to the suction side of a recycle pump 19 located
below the flow distributor 21, to assure a positive and controlled
upward movement of the liquid through the catalyst bed ~2.
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Operability of the ebullated catalyst bed reactor system
to assure good contact and uniform (iso-thermal) temperature 3
therein depends not only on the random ~otion of the catalyst in
the liquid environment resulting from the buoyant effect of the
upflowing liquid and gas, but also requires the proper reaction
conditions. With improper reaction conditions,insufficient de- i
metallization of the feedstock is achieved. For the ~etroleum 3
feedstocks useful in this invention, i.e., those having total
metals at least about 200 ppm, operating conditions needed in the
reactor 20 are within ranges of 780-850F temperature, 1000-3000
psig, hydrogen partial pressure, and space velocity of 0.20-1.50
Vf/hr/Vr ~volume feed per hour per volume of reactor). Preferred
reaction conditions are 790-830F temperature, 1500-2800 psig,
hydrogen partial pressure, and space velocity of 0.25-1.20
Vf/hr/Vr. The feedstock hydroconversion achieved is about 5U-70
% for the first stage of once through type operations.
In an ebullatéd bed reactor system, a vapor space 23 existsi
above the liquid level 23a and an overhead stream containing both
liquid and gas portions is withdrawn at 27, and passed to hot
phase separator 28. The resulting gaseous portion 29 is princi-
pally hydrogen, which is cooled at heat exchanger 30, and may be
recovered in gas purification step 32. The recovered hydrogen
at 33 is warmed at heat exchanger 30 and recycled ~y compressor 34
through conduit 35, reheated at heater 36, and is passed into the
bottom of reactor 20 along with make-up hydrogen at 35a as needed.
From phase separator 28, liquid portion stream 38 is with-
drawn, pressure-reduced at 39 to pressure below about 200 psig,
and passed to fractionation step 40. A condensed vapor stream
also is withdrawn at 37 from gas purification step 32 and also
passed to fractionation step 40, from which is withdrawn a low
pressure gas stream 41. Thi~ vapor stream is phase separated at
~.Z~7~7~;6
42 to provide low pressure gas product 43 and liquid stream 44 to
provide reflux liquid to fractionator 40 and naphtha product
stream 45. A middle boiling range distillate liquid product
stream is withdrawn at 46, and a heavy hydrocarbon liquid stream
~s withdra~n at 48. .
From fractionator 40, the heavy oil stream 48 which usualiy~
,. has normal ~oiling temperature range of 650F+, is withdrawn,
i reheated in heater 49 and passed to vacuum distillation step 50.
A vacuum gas oil stream is withdrawn at 52, and vacuum bottoms
stream is withdrawn at 54. If desired for two-stage e~ullated bed;
reactor operations, a portion 55 of the vacuum bottoms material
usually boiling above about 975F can be recycled to the reactor
system for further hydroconversion. A heavy vacuum bottcms material
is withdrawn at 56.
, This invention will be further described by reference to
the following examples, which should not be construed as limiting ,
in scope.
. EXAMPLE 1
The fluid dynamics characteristics of the spherical shaped
: 12-18 mesh size LX-102 catalyst were determined in a laboratory
catàlyst ebullation test conducted in a 1 inch diameter glass tube;
`apparatus using nitrogen gas and liquid heptane to simulate typical
e~ ated bed reaction operations. Specific characteristics of the synthetic
catalyst used are pravided ~ ~able 2. For catalyst bed expansions of 20-60%
ab~ve its settled level using upward gas velocities of 0.04-0.16 fps and liquid
velocities of 0.10-0.15 fps, the catalyst bed interface bet~ catalyst and
liquid was stable and the bed expansion correlated well with ex-
pected values. Comparative results of catalyst bed expansion vs.
upflowing liquid superficial velocity are shown in FIG.2.
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TABLE 2
INSPECTION OF FRESH SYNTHETIC CATALYST
Gatalyst Designation LX-102
Nominal Size (U.S. Sieve Series) 12-18 Mesh
Molybdenum (Nominal), W % 1 6
Physical Properties
Surface Area, M /gm 163
Pore Volume, cc/gm ( 30 A) 0.442
; Compacted Bulk Density, gm/cc 0.815
Attrition Loss, W ~ - 30 Mesh 1.6
Pore Size Distribution (Pore Volume)
30 ~ ~iameter, cc/gm 0.442
250 R Diameter, cc/gm 0.234
500 R Diameter, cc/gm 0.214
1500 A Diameter, cc/gm 0.194
4000 R Diameter, cc/gm 0.141 3
It was observed that the catalyst e~bited smcoth operation in the re-
~actor with well defined upper le~el for the catalyst bed over a wide range of
percentage bed expansion.
E~1E 2
To verify the catalyst attrition and carryover rate per~
; formance for the spherical catalyst under actual reaction condi-
tions at typical elevated temperatures and pressures, a sustained
run of over 5 days duration was conducted using 12-18 mesh size
LX-102 catalyst in an 0.6 inch diameter single stage ebullated bed
reactor at about 810-815F temperature and 2100-2400 psig hydrogen
partial pressure conditions, using a typical petroleum residuum
; feedstock containing high metals and sulfur. Characteristics of
the catalyst used are shown in Table 2 and characteristics of the
feedstock used are shown in Table 3.
~2~7~S~
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TABLE 3
FEEDSTOCK INSPECTIONS
Feedstock Bachaquero Vacuum Bottoms
Gravity, API 5.8- 6.3
Sulfur, W % 3.36- 3.71
Carbon, W % 85.2-85.90
Hydrogen, W % 10.3-10.35
RCR, W % 16.3-19.51
Nitrogen, ppm 5900-6200
Vanadium, ppm 650- 795
Nickel, ppm 87- 89
IBP-975 ~raction
Volume, % 18-20
Gravity, API 14.0-14.7
Sulfur, W % 2.6- 2.74
975F+ Frac~ion
!
Volume, % 80-81.6
Gravity, API 3.7- 4.7
Sulfur, W % 3.6- 3.84
Vanadium, ppm 780-1000
Nickel, ppm 100- 130
Typical operating results obtained from ebullated catalyst
bed hydrodemetallization operations in the one-stage, single pass
laboratory size catalytic reactor are summarized in Table 4 below:
TABLE 4
.
Catalyst Designation LX-102
Feedstock Bachaquero Vacuum Bottoms
Reactor Conditions.
Temperature, F 810-815
Hydrogen Partial Pressure, psig 2250
Space Velocity, Vf/hr/Vr 0.6
Operatinq Results:
975F+Conversion, V % 57_59
RCR Conversion, W ~ 33.6
Vanadium Removal, W % 65
Nickel Removal~ W % 45
Sulfur Removal~ W ~ 51
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~1 ~z~77s6
Laboratory tests were conducted on a petroleum residua
¦¦material in a small scale reactor having 0.62 inch inside dia-
¦lmeter. Results showed that this new catalyst was ef~ective in re-
moving metal and sulfur compounds from the feedstock and in con-
Iverting the 975F+ material to lower boiling fractions.
Although this invention has been described broadly and with
reference to certain preferred embodiments thereof, it will be
understood that modifications and variations of the process can be
made and that some steps can be used without others all within the
spirit and scope of the invention, which is defined by the follow-
~ng laims.
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