Note: Descriptions are shown in the official language in which they were submitted.
CA 02341175 2001-02-19
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FISCHER-TROPSCH PROCESSES USING
CATALYSTS ON MESOPOROUS SUPPORTS
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. provisional patent application
Serial Number
60/097,192, filed August 20, 1998, U.S. provisional patent application Serial
Number 60/097,193,
filed August 20, 1998, and U.S. provisional patent application Serial Number
60/097,194, filed
August 20, 1998, all of which are incorporated herein by reference in their
entirety.
STATEMENT REGARDING FEDERALLY SPONSORED
RESEARCH OR DEVELOPMENT
Not applicable.
FIELD OF THE INVENTION
The present invention relates to a process for the preparation of hydrocarbons
from synthesis
gas, (i.e., a mixture of carbon monoxide and hydrogen), typically labeled the
Fischer-Tropsch
process. Particularly, this invention relates to supported catalysts
containing metals on mesoporous
materials.
BACKGROUND OF THE INVENTION
Large quantities of methane, the main component of natural gas, are available
in many areas
of the world. Methane can be used as a starting material for the production of
hydrocarbons. The
conversion of methane to hydrocarbons is typically carried out in two steps.
In the first step methane
is reformed with water or partially oxidized with oxygen to produce carbon
monoxide and hydrogen
(i.e., synthesis gas or syngas). In a second step, the syngas is converted to
hydrocarbons.
The preparation of hydrocarbons from synthesis gas is well known in the art
and is usually
referred to as Fischer-Tropsch synthesis, the Fischer-Tropsch process, or
Fischer-Tropsch
reaction(s). Catalysts for use in such synthesis usually contain a
catalytically active Group VIII
(CAS) metal. In particular, iron, cobalt, nickel, and ruthenium have been
abundantly used as the
catalytically active metals. Cobalt and ruthenium have been found to be most
suitable for catalyzing
a process in which synthesis gas is converted to primarily hydrocarbons having
five or more carbon
atoms (i.e., where the CS+ selectivity of the catalyst is high). Additionally,
the catalysts often
contain one or more promoters and a support or carrier material. Rhenium is a
widely used promoter.
The Fischer-Tropsch reaction involves the catalytic hydrogenation of carbon
monoxide to
produce a variety of products ranging from methane to higher aliphatic
alcohols. The methanation
reaction was first described in the early 1900's, and the later work by
Fischer and Tropsch dealing
with higher hydrocarbon synthesis was described in the 1920's.
The Fischer-Tropsch synthesis reactions are highly exothermic and reaction
vessels must be
designed for adequate heat exchange capacity. Because the feed streams to
Fischer-Tropsch reaction
vessels are gases while the product streams include liquids, the reaction
vessels must have the ability
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to continuously produce and remove the desired range of liquid hydrocarbon
products. The process
has been considered for the conversion of carbonaceous feedstock, e.g., coal
or natural gas, to higher
value liquid fuel or petrochemicals. The first major commercial use of the
Fischer-Tropsch process
was in Germany during the 1930's. More than 10,000 B/D (barrels per day) of
products were
manufactured with a cobalt based catalyst in a fixed-bed reactor. This work
has been described by
Fischer and Pichler in Ger. Pat. No. 731,295 issued Aug. 2, 1936.
Motivated by production of high-grade gasoline from natural gas, research on
the possible
use of the fluidized bed for Fischer-Tropsch synthesis was conducted in the
United States in the mid-
1940s. Based on laboratory results, Hydrocarbon Research, Inc. constructed a
dense-phase fluidized
bed reactor, the Hydrocol unit, at Carthage, Texas, using powdered iron as the
catalyst. Due to
disappointing levels of conversion, scale-up problems, and rising natural gas
prices, operations at this
plant were suspended in 1957. Research has continued, however, on developing
Fischer-Tropsch
reactors such as slurry-bubble columns, as disclosed in U.S Patent No.
5,348,982 issued September
20, 1994.
Commercial practice of the Fischer-Tropsch process has continued from 1954 to
the present
day in South Africa in the SASOL plants. These plants use iron-based
catalysts, and produce
gasoline in relatively high-temperature fluid-bed reactors and wax in
relatively low-temperature
fixed-bed reactors.
Research is likewise continuing on the development of more efficient Fischer-
Tropsch
catalyst systems and reaction systems that increase the selectivity for high-
value hydrocarbons in the
Fischer-Tropsch product stream. In particuiar, a number of studies describe
the behavior of iron,
cobalt or ruthenium based catalysts in various reactor types, together with
the development of catalyst
compositions and preparations.
There are significant differences in the molecular weight distributions of the
hydrocarbon
products from Fischer-Tropsch reaction systems. Product distribution or
product selectivity depends
heavily on the type and structure of the catalysts and on the reactor type and
operating conditions.
Accordingly, it is highly desirable to maximize the selectivity of the Fischer-
Tropsch synthesis to the
production of high-value liquid hydrocarbons, such as hydrocarbons with five
or more carbon atoms
per hydrocarbon chain.
U.S. Pat. No. 4,659,681 issued on Apr. 21, 1987, describes the laser synthesis
of iron based
catalyst particles in the 1-100 micron particle size range for use in a slurry
reactor for Fischer-
Tropsch synthesis.
U.S. Pat. No. 4,619,910 issued on Oct. 28, 1986, U.S. Pat. No. 4,670,472
issued on Jun. 2,
1987, and U.S. Pat. No. 4,681,867 issued on Jul. 21, 1987, describe a series
of catalysts for use in a
slurry Fischer-Tropsch process in which synthesis gas is selectively converted
to higher hydrocarbons
of relatively narrow carbon number range. Reactions of the catalyst with air
and water and
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calcination are specifically avoided in the catalyst preparation procedure.
The catalysts are activated
in a fixed-bed reactor by reaction with CO+ HZ prior to slurrying in the oil
phase in the absence of air.
Catalyst supports for catalysts used in Fischer-Tropsch synthesis of
hydrocarbons have
typically been oxides (e.g., silica, alumina, titania, zirconia or mixtures
thereof, such as silica
alumina). It has been claimed that the Fischer-Tropsch synthesis reaction is
only weakly dependent
on the chemical identity of the metal oxide support (see E. Iglesia et al.
1993, In: "Computer-Aided
Design of Catalysts," ed. E. R. Becker et al., p. 215, New York, Marcel
Dekker, Inc.). The products
prepared by using these catalysts usually have a very wide range of molecular
weights.
U.S. Pat. No. 4,477,595 discloses ruthenium on titania as a hydrocarbon
synthesis catalyst for
the production of CS to C40 hydrocarbons, with. a majority of paraffins in the
CS to C20 range. U.S.
Pat. No. 4,542,122 discloses a cobalt or cobalt-thoria on titania having a
preferred ratio of rutile to
anatase, as a hydrocarbon synthesis catalyst. U.S. Pat. No. 4,088,671
discloses a cobalt-ruthenium
catalyst where the support can be titania but preferably is alumina for
economic reasons. U.S. Pat.
No. 4,413,064 discloses an alumina supported catalyst having cobalt, ruthenium
and a Group IIIA or
Group 1VB metal oxide, e.g., thoria. European Patent No. 142,887 discloses a
silica supported cobalt
catalyst together with zirconium, titanium, ruthenium and/or chromium.
U.S. Pat. No. 4,801,573 discloses a promoted cobalt and rhenium catalyst,
preferably
supported on alumina that is characterized by low acidity, high surface area,
and high purity, which
properties are said to be necessary for high activity, low deactivation, and
high molecular weight
products. The amount of cobalt is most preferably about 10 to 40 wt % of the
catalyst. The content
of rhenium is most preferably about 2 to 20 wt % of the cobalt content.
Related U.S. Pat. No.
4,$57,559 discloses a catalyst most preferably having 10 to 45 wt % cobalt and
a rhenium content of
about 2 to 20 wt % of the cobalt content. In both of the above patents the
method of depositing the
active metals and promoter on the alumina support is described as not
critical.
U.S. Pat. No. 5,545,674 discloses a cobalt-based catalyst wherein the active
metal is
dispersed as a very thin film on the surface of a particulate support,
preferably silica or titania or a
titania-containing support. The catalyst may be prepared by spray techniques.
U.S. Pat. No. 5,028,634 discloses supported cobalt-based catalysts, preferably
supported on
high surface area aluminas. High surface area supports are said to be
preferred because greater cobalt
dispersion can be achieved as cobalt is added, with less tendency for one
crystal of cobalt to fall on
another crystal of cobalt. The cobalt loading on a titania support is
preferably 10 to 25 wt %, while
the preferred cobalt loading on an alumina support is 5 to 45 wt %.
International Publication Nos. WO 98/47618 and WO 98/47620 disclose the use of
rhenium
promoters and describe several functions served by the rhenium.
U.S Pat. No. 5,248,701 discloses a copper promoted cobalt-manganese spinel
that is said to
be useful as a Fischer-Tropsch catalyst with selectivity for olefins and
higher para~ns.
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U.S. Pat. No. 5,302,622 discloses a supported cobalt and ruthenium based
catalyst including
other components and preferably prepared by a gelling procedure to incorporate
the catalyst
components in an alcogel formed from a hydrolyzable compound of silicon,
and/or aluminum, and
optional compounds. The cobalt content after calcination is preferably between
14 and 40 wt % of
the catalyst.
UK Patent Application GB 2,258,414A, published February 10, 1993, discloses a
supported
catalyst containing cobalt, molybdenum and/or tungsten, and an additional
element. The support is
preferably one or more oxides of the elements Si, AI, Ti, Zr, Sn, Zn, Mg, and
elements with atomic
numbers from 57 to 71. After calcination, the prefeaed cobalt content is from
5 to 40 wt % of the
catalyst. A preferred method of preparation. of the catalyst includes the
preparation of a gel
containing the cobalt and other elements.
A gel may be described as a coherent, rigid three-dimensional polymeric
network. The
present gels are formed in a liquid medium, usually water, alcohol, or a
mixture thereof. The term
"alcogel" describes gets in which the pores are filled with predominantly
alcohol. Gels whose pores
are filled primarily with water may be referred to as aquagels or hydrogels.
A "xerogel" is a gel from which the liquid medium has been removed and
replaced by a gas.
In general, the structure is compressed and the porosity reduced significantly
by the surface tension
forces that occur as the liquid is removed. As soon as liquid begins to
evaporate from a gel at
temperatures below the critical temperature, surface tension creates concave
menisci in the gel's
pores. As evaporation continues, the menisci retreat into the gel body,
compressive forces build up
around its perimeter, and the perimeter contracts, drawing the gel body
inward. Eventually surface
tension causes significant collapse of the gel body and a reduction of volume,
often as much as two-
thirds or more of the original volume. This shrinkage causes a significant
reduction in the porosity,
often as much as 90 to 95 percent depending on the system and pore sizes.
In contrast, an "aerogel" is a gel from which the liquid has been removed in
such a way as to
prevent significant collapse or change in the structure as liquid is removed.
This is typically
accomplished by heating the liquid-filled gel in an autoclave while
maintaining the prevailing
pressure above the vapor pressure of the liquid until the critical temperature
of the liquid has been
exceeded, and then gradually releasing the vapor, usually by gradually
reducing the pressure either
incrementally or continuously, while maintaining the temperature above the
critical temperature. The
critical temperature is the temperature above which it is impossible to
liquefy a gas, regardless of
how much pressure is applied. At temperatures above the critical temperature,
the distinction
between liquid and gas phases disappears and so do the physical manifestations
of the gas/liquid
interface. In the absence of an interface between liquid and gas phases, there
is no surface tension
and hence no surface tension forces to collapse the gel. Such a process may be
termed "supercritical
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drying." Aerogels produced by supercritical drying typically have high
porosities, on the order of
from 50 to 99 percent by volume.
International Publication No. WO 96/19289 discloses active metal coated
catalysts supported
on an inorganic oxide, and notes that dispersion of the active metal on
Fischer-Tropsch catalysts has
essential effects on the activity of the catalyst and on the composition of
the hydrocarbons obtained.
Despite the vast amount of research effort in this field, there is still a
great need for new
catalysts for Fischer-Tropsch synthesis, particularly catalysts that provide
high CS+ hydrocarbon
selectivities to maximize the value of the hydrocarbons produced and thus
enhance the process
economics.
SUMMARY OF THE INVENTION
This invention provides a process for producing hydrocarbons. The process
comprises
contacting a feed stream comprising hydrogen and carbon monoxide with a
catalyst in a reaction zone
maintained at conversion-promoting conditions effective to produce an effluent
stream comprising
hydrocarbons. In accordance with this invention the catalyst used in the
process comprises (a) at
1 S least one catalytic metal for Fischer-Tropsch reactions (e.g., at least
one metal selected from the
group consisting of iron, cobalt, nickel and ruthenium); and (b) a non-layered
mesoporous support
which exhibits an X-ray diffraction after calcination that has at least one
peak at a d-spacing of
greater than 18 Angstrom units.
In accordance with this invention, the catalyst used in the process comprises
a catalytically
active metal seiected from the group consisting of iron, cobalt, nickel,
ruthenium, and combinations
thereof, a support material comprising an inorganic, non-layered mesoporous
crystalline phase with a
composition represented by M~q(WaXbYcZdOh) where M is at least one ion
selected from the
group consisting of ammonium, sodium, potassium, and hydrogen, n is the charge
of the composition
excluding M expressed as oxides, q is the weighted molar average valence of M,
n/q is the mole
fraction of M, W is at least one divalent element, X is at least one trivalent
element, Y is at least one
tetravalent element, Z is at least one pentavalent, a, b, c, and d are mole
fractions of W, X, Y and Z,
respectively, h is a number from 1 to 2.5, and (a + b + c + d) = 1.
This invention also includes a Fischer-Tropsch catalyst comprising at least
one catalytically
active metal and a non-layered mesoporous support that exhibits an X-ray
diffraction pattern after
calcination that has at Ieast one peak at a d-spacing of greater than 18
angstrom units.
This invention also includes a method for the preparation of a Fischer-Tropsch
catalyst
comprising impregnating a support with a salt of a catalytically active metal
selected from the group
consisting of iron, cobalt, nickel, ruthenium, and combinations thereof,
wherein the support
comprises a non-layered mesoporous support that exhibits an X-ray diffraction
pattern after
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calcination that has at least one peak at a d-spacing of greater than 18
Angstrom units, and drying the
impregnated support.
DETAILED DESCRIPTION OF THE INVENTION
The feed gases charged to the process of the invention comprise hydrogen, or a
hydrogen
source, and carbon monoxide. H2/CO mixtures suitable as a feedstock for
conversion to
hydrocarbons according to the process of this invention can be obtained from
light hydrocarbons such
as methane by means of steam reforming, partial oxidation, or other processes
known in the art. The
hydrogen is preferably provided by free hydrogen, although some Fischer-
Tropsch catalysts have
sufficient water gas shift activity to convert some water to hydrogen for use
in the Fischer-Tropsch
process. It is preferred that the molar ratio of.hydrogen to carbon monoxide
in the feed be greater
than 0.5:1 (e.g., from about 0.67 to 2.5). When cobalt, nickel, and/or
ruthenium catalysts are used,
the feed gas stream preferably contains hydrogen and carbon monoxide in a
molar ratio of about 2:1.
When iron catalysts are used, the feed gas stream preferably contains hydrogen
and carbon monoxide
in a molar ratio of about 0.67:1. The feed gas may also contain carbon
dioxide. The feed gas stream
should contain a low concentration of compounds or elements that have a
deleterious effect on the
catalyst, such as poisons. For example, the feed gas may need to be pre-
treated to ensure that it
contains low concentrations of sulfur or nitrogen compounds, such as hydrogen
sulfide, ammonia and
carbonyl sulfides.
The feed gas is contacted with the catalyst in a reaction zone. Mechanical
arrangements of
conventional design may be employed as the reaction zone including, for
example, fixed bed,
fluidized bed, slurry phase, slurry bubble column or ebullating bed reactors,
among others, may be
used. Accordingly, the size and physical form of the catalyst particles may
vary depending on the
reactor in which they are to be used.
A component of the catalysts used in this invention is the support material
(b) which carries
the active catalyst component (a). Typically, the support material contains an
inorganic, non-layered
mesoporous crystalline phase with a composition of the formula:
M~q(WaXbYcZaOh) where M is
one or more ions such as ammonium, sodium, potassium and/or hydrogen; n is the
charge of the
composition excluding M expressed as oxides; q is the weighted molar average
valence of M; n/q is
the number of moles or mole fraction of M; W is one or more divalent elements
such as a divalent
first row transition metal, (e.g., manganese, iron and cobalt) and/or
magnesium, preferably cobalt; X
is one or more trivalent elements such as aluminum, boron, iron and/or
gallium, preferably aluminum;
Y is one or more tetravalent elements (e.g., titanium, zirconium, hafnium,
manganese, silicon and/or
germanium), preferably silicon; Z is one or more pentavalent elements (e.g.,
niobium, tantalum,
vanadium and phosphorus) preferably phosphorus; a, b, c, and d are mole
fractions of W, X, Y and Z,
respectively; h is a number from 1 to 2.5; and (a + b + c + d) = 1.
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A preferred embodiment of the above composition is where the sum (a + b + c)
is greater
than d, and h is 2. A further embodiment is when a and d are 0, and h is 2.
Also preferred are compositions where (a + b + c) is less than d and h is 2.5
and Z is niobium
or tantalum (e.g., Nb205 and Ta205).
Further details about the preparation and characterization of the above-
described inorganic,
non-layered mesoporous crystalline phase compositions are described in U.S.
Patent No. 5,232,580
which is incorporated by reference herein in its entirety. Descriptions of
mesoporous molecular sieve
materials and their use in catalysis can be found in A. Corms, Chem. Rev.
(1997), 97, 2373-2419,
hereby incorporated herein by reference in its entirety.
The silica-based mesoporous M415 molecular sieves are preferred in the
preparation of the
catalysts of the present invention. These include Si-MCM-41 and AI-MCM-41,
where Si-MCM-41
refers to purely siliceous MCM-41 and AI-MCM-41 refers to MCM-41 where some Si
atoms have
been replaced by Al atoms.
Another component of the catalyst of the present invention is the catalytic
metal. The
catalytic metal is preferably selected from iron, cobalt, nickel and/or
ruthenium. Normally, the metal
component on the support is reduced to provide elemental metal (e.g.,
elemental iron, cobalt, nickel
andlor ruthenium) before use. The catalyst contains a catalytically effective
amount of the metal
component(s). The amount of catalytic metal present in the catalyst may vary
widely. Typically, the
catalyst comprises about 1 to 50% by weight (as the metal) of total supported
iron, cobalt, nickel
and/or ruthenium per total weight of catalytic metal and support, preferably,
about 1 to 30% by
weight.
Each of the metals can be used individually or in combination with other
metals, especially
cobalt and ruthenium, cobalt and rhenium, and cobalt and platinum. Preferred
are catalysts
comprising from about 10 to 30% by weight of a combination of cobalt and
ruthenium where the
ruthenium content is from about 0.001 to about 1 weight %.
Optionally, the catalyst may comprise one or more additional promoters or
modifiers known
to those skilled in the art. When the catalytic metal is iron, cobalt, nickel
and/or ntthenium, suitable
promoters include at least one metal selected from the group consisting of
Group IA (CAS) metals
(i.e., Na, K, Rb, Cs), Group IIA metals (i.e., Mg, Ca, Sr, Ba), Group IB
metals (i.e., Cu, Ag, and Au),
Group IIIB metals (i.e., Sc, Y and La), Group IVB metals (i.e., Ti, Zr and
Hf), Group VB metals (i.e.,
V, Nb and Ta), and Rh, Pd, Os, Ir, Pt, Mn, B, P, and Re. Preferably, any
additional promoters for the
cobalt and/or ruthenium are selected from Sc, Y and La, Ti, Zr, Hf, Rh, Pd,
Os, Ir, Pt, Re, Nb, Cu,
Ag, Mn, B, P, and Ta. Preferably, any additional promoters for the iron
catalysts are selected from
Na, K, Rb, Cs, Mg, Ca, Sr and Ba. The amount of additional promoter, if
present, is typically
between 0.001 and 40 parts by weight per 100 parts of the support or carrier.
Combinations of cobalt
and rhenium and combinations of cobalt and platinum are preferred. More
preferred are catalysts
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comprising from about 10 to 30% by weight of a combination of cobalt and
rhenium, where the
rhenium content is from about 0.001 to about 1 weight %; and catalysts
comprising from about 10 to
30% of a combination of cobalt and platinum where the platinum content is from
about 0.001 to
1 weight %.
The catalysts of the present invention may be prepared by methods known to
those skilled in the art.
These include impregnating the catalytically active compounds or precursors
onto a support,
extruding one or more catalytically active compounds or precursors together
with support material to
prepare catalyst extrudates and spray-drying the supported catalytically
active compounds.
Accordingly, the supported catalysts of the present invention may be used in
the form of powders,
particles, pellets, monoliths, honeycombs, packed beds, foams, and aerogels.
The most preferred method of preparation may vary among those skilled in the
art, depending
for example on the desired catalyst particle size. Those skilled in the art
are able to select the most
suitable method for a given set of requirements.
One method of preparing a supported mete) catalyst (e.g., a supported cobalt
catalyst) is by
incipient wetness impregnation of the support with an aqueous solution of a
soluble metal salt such as
nitrate, acetate, acetylacetonate or the like. Another method involves
preparing the catalyst from a
molten metal salt. For example, the support can be impregnated with a molten
metal nitrate (e.g.,
Co(N03)2~6H20). Alternatively, the support can be impregnated with a solution
of zero valent
cobalt such as Co2(CO)g, Co4(CO)12 or the like in a suitable organic solvent
(e.g., toluene). The
impregnated support is dried and reduced with hydrogen. The hydrogen reduction
step may not be
necessary if the catalyst is prepared with zero valent cobalt. In another
embodiment, the impregnated
support is dried, oxidized with air or oxygen and reduced with hydrogen.
Typically, at least a portion of the metals) of the catalytic metal component
(a) of the
catalysts of the present invention is present in a reduced state (i.e., in the
metallic state). Therefore, it
is normally advantageous to activate the catalyst prior to use by a reduction
treatment, in the presence
of hydrogen at an elevated temperature. Typically, the catalyst is treated
with hydrogen at a
temperature in the range of from about 75°C to about 500°C, for
about 0.5 to about 24 hours at a
pressure of about 1 to about 75 atm. Pure hydrogen may be used in the
reduction treatment, as well
as a mixture of hydrogen and an inert gas such as nitrogen. The amount of
hydrogen may range from
about 1% to about 100% by volume.
The Fischer-Tropsch process is typically run in a continuous mode. In this
mode, the gas
hourly space velocity through the reaction zone typically may range from about
100 volumes/hour/volume catalyst (v/hr/v) to about 10,000 v/hr/v, preferably
from about 300 v/hr/v
to about 2,000 v/hr/v. The reaction zone temperature is typically in the range
from about 160°C to
about 300°C. Preferably, the reaction zone is operated at conversion
promoting conditions at
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temperatures from about 190°C to about 260°C. The reaction zone
pressure is typically in the range
of about 80 psig (653 kPa) to about 1000 psig (6994 kPa), preferably, from 80
psig (653 kPa) to about
600 psig (4237 kPa), and still more preferably, from about 140 psig (1066 kPa)
to about 400 psig
(2858 kPa).
S The products resulting from the process will have a great range of molecular
weights.
Typically, the carbon number range of the product hydrocarbons will start at
methane and continue to
the limits observable by modern analysis, about 50 to 100 carbons per
molecule. The process is
particularly useful for making hydrocarbons having five or more carbon atoms,
especially when the
above-referenced preferred space velocity, temperature and pressure ranges are
employed.
The wide range of hydrocarbons produced in the reaction zone will typically
afford liquid
phase products at 'the reaction zone operating conditions. Therefore the
effluent stream of the
reaction zone will often be a mixed phase stream including liquid and vapor
phase products. The
effluent stream of the reaction zone may be cooled to effect the condensation
of additional amounts
of hydrocarbons and passed into a vapor-liquid separation zone separating the
liquid and vapor phase
products. The vapor phase material may be passed into a second stage of
cooling for recovery of
additional hydrocarbons. The liquid phase material from the initial vapor-
liquid separation zone,
together with any liquid from a subsequent separation zone, may be fed into a
fractionation column.
Typically, a stripping column is employed first to remove light hydrocarbons
such as propane and
butane. The remaining hydrocarbons may be passed into a fractionation column
where they are
separated by boiling point range into products such as naphtha, kerosene and
fuel oils. Hydrocarbons
recovered from the reaction zone and having a boiling point above that of the
desired products may
be passed into conventional processing equipment such as a hydrocracking zone
in order to reduce
their molecular weight. The gas phase recovered from the reactor zone effluent
stream after
hydrocarbon recovery may be partially recycled if it contains a sufficient
quantity of hydrogen and/or
carbon monoxide.
Without further elaboration, it is believed that one skilled in the art can,
using the description
herein, utilize the present invention to its fullest extent. The following
embodiments are to be
construed as illustrative, and not as constraining the scope of the present
invention in any way
whatsoever.
General Procedure For Batch Tests
Each of the catalyst samples was treated with hydrogen prior to use in the
Fischer-Tropsch
reaction. The catalyst sample was placed in a small quartz crucible in a
chamber and purged with
500 sccm (8.3 x 10'6 m3/s) nitrogen at room temperature for 15 minutes. The
sample was then
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heated under 100 sccm ( I .7 x 10'6 m3/s) hydrogen at 1 °C/minute to
100°C and held at 100°C for one
hour. The catalysts were then heated at 1 °C/minute to 400°C and
held at 400°C for four hours under
100 sccm (1.7 x 10-6 m3/s) hydrogen. The samples were cooled in hydrogen and
purged with
nitrogen before use. Examples 9 and 10 were heat treated under helium as
described in the specific
examples.
A 2 mL pressure vessel was heated at 225°C under 1000 psig {6994 kPa)
of H2:C0 (2:1) and
maintained at that temperature and pressure for 1 hour. In a typical run,
roughly 50 mg of the
hydrogen catalyst and 1 mL of n-octane was added to the vessel. After one
hour, the reactor vessel
was cooled in ice, vented, and an internal standard of di-n-butylether was
added. The reaction
product was analyzed on an HP6890 gas chrornatograph. Hydrocarbons in the
range of C11-C40
were analyzed relative to the internal standard. The lower hydrocarbons were
not analyzed since they
are masked by the solvent and are also vented as the pressure is reduced.
A CI1+ Productivity {g C11+/hour/kg catalyst) was calculated based on the
integrated
production of the C11-C40 hydrocarbons per kg of catalyst per hour. The
logarithm of the weight
fraction for each carbon number ln(Wn/n) was plotted as the ordinate vs.
number of carbon atoms in
(Wn/n) as the abscissa. From the slope, a value of alpha was obtained. Some
runs displayed a double
alpha as shown in the tables. The results of runs over a variety of catalysts
at 225°C are shown in
Table I.
Support Preparation
A. Si-M- A stiff homogeneous gel was prepared by shaking AerosilTM 200 Si02
(20 g), H20 (95.4 g) and a 50% NaOH solution (9.07 g) in a 500 mL polyolefin
bottle. A solution of
dodecyltrimethylammonium bromide (51.39 g) in H20 (80.1 g) was added to the
polyolefin bottle,
and the contents of the closed bottle were stirred with a magnetic stirrer for
1 hour. Shaking may be
necessary to start the stirring. The product gel was poured into a Teflon~
(polytetrafluoroethylene)
bottle; the bottle was sealed and put into an oven at 95°C for 5 days.
The solids were filtered, washed
with hot water until foaming stopped and dried. The solids were then calcined
in air at the following
according to the following schedule rates: from room temperature to
110°C at 10°C/min.; from
110°C to 200°C at 5°C/min.; and finally from 200°C
to 550°C at 1°C/min., where it was held for
4 hours before cooling to room temperature. An X-ray diffraction pattern of a
sample of the
recovered calcined solids showed it to have the MCM-41 structure with a peak
at a d-spacing of
38 Angstroms. The Si-MCM-41 was used to prepare the catalyst described in
Examples 1 to 9.
B. AI-~ A thin suspension of AerosilT"" 200 Si02 (10.1 g), H20 (40 g) and
tetramethylammoniumhydroxide (5.36 g, 25% in H20) was prepared in a polyolefin
bottle. The
CA 02341175 2001-02-19
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suspension was stirred for 20 minutes. To a solution of
cetyltrimethylammoniumbromide (18.98 g),
H20 (144.4 g) and a 50% in H20 NaOH solution (2.34 g) prepared by warming in a
water-bath was
added the Si02 suspension and stirred for 20 minutes. Aluminum isopropoxide
(1.357 g) was added
to the suspension and stirring was maintained for 12 minutes. The product was
poured into a
Teflon~ (polytetrafluoroethylene) bottle; the bottle was sealed and put into
an oven at 100°C for
3 days and 3 hours. The solids were filtered, washed with hot deionized water
(3 L) and vacuum
dried. The solids were then calcined in air at the following rates: from room
temperature to 110°C at
10°C/min.; from 110°C to 200°C at 5°C/min.; and
finally from 200°C to 550°C at 1 °C/min., where it
was held for 4 hours before cooling to room temperature. An X-ray diffraction
pattern of a sample of
the recovered calcined solids showed it to have the MCM-41, with a peak at a d-
spacing of
29 Angstroms. The AI-MCM-42 was used to prepare the catalyst described in
Example 10.
Catalyst Synthesis
EXAMPLE 1
Si-MCM-41 (2 g) was slurried with an aqueous solution of RuCl3 (0.2 g) in a
rotary
evaporator. The water was removed under vacuum at 70°C. The dried
material was calcined at
250°C under 1500 cc/minute of air.
The catalyst had a nominal composition of 5 wt. % Ru on Si-MCM-41.
EXAMPLE 2
Si-MCM-41 (1.8 g) was slurned with an aqueous solution of RuCl3 (0.36 g) in a
rotary
evaporator. The water was removed under vacuum at 70°C. The dried
material was calcined at
250°C under 1500 cc/minute of air.
The catalyst had a nominal composition of 10 wt. % Ru/Si-MCM-41.
EXAMPLE 3
Si-MCM-41 (2 g) was slurried with an aqueous solution of Co(N03)2~6H20 (1.6 g)
in a
rotary evaporator. The water was removed under vacuum at 70°C. The
dried material was calcined
at 250°C under 1500 cc/minute of air. This material was slurried with
an aqueous solution of
Co(N03)2~6H20 (1.4 g) and Pt(NH3)4(N03)2 (2.5 mg) in a rotary evaporator. The
water was
removed under vacuum at 70°C. The dried material was calcined at
250°C under 1500 cc/minute of
air.
The catalyst had a nominal composition of 25 wt. % Co/0.08 wt. % PdSi-MCM-41.
EXAMPLE 4
Si-MCM-41 (2 g) was slurried with an aqueous solution of Pt(NH3)4(N03)2 (2.5
mg). The
water was removed under vacuum at 70°C. This material was slurried with
an aqueous solution of
Co(N03)2~6H20 (1.6 g) in a rotary evaporator. The water was removed under
vacuum at 70°C. The
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dried material was calcined at 250°C under 1500 cc/minute of air. This
material was slurried with an
aqueous solution of 1.4 g Co(IV03~~6H20 and in a rotary evaporator. The water
was removed under
vacuum at 70°C. The dried material was calcined at 250°C under
1500 cc/minute of air.
The catalyst had a nominal composition of 25 wt. % Co/0.05 wt. % Pt/Si-MCM-41.
EXAMPLE 5
Si-MCM-41 (1.5 g) was slurried with an aqueous solution of Co(CH3C00~~4H20
(0.95 g)
in a rotary evaporator. The water was removed under vacuum at 70°C. The
dried material was
calcined at 250°C under 1500 cc/minute of air. This material is
designated Example SA. A portion
of this material (0.65 g) was slurried with an acetone solution of
Co(CH3COOn~4H20 (0.4 g) and
IO ruthenium acetylacetonate (3 mg, Ruacac3) in a rotary evaporator. The
acetone was removed under
vacuum at 70°C. The dried material was calcined at 250°C under
1500 cc/minute of air.
The catalyst had a nominal composition of 25 wt. % Co/0.1 wt. % Ru/Si-MCM-41.
EXAMPLE 6
Si-MCM-41 (1.5 g) was slurried with an aqueous solution of Co(N03)2~6H20 (1.2
g) in a
15 rotary evaporator. The water was removed under vacuum at 70°C. The
dried material was calcined
at 250°C under 1500 cc/minute of air. This material is designated
Example 6B. A portion of this
material (0.85 g) was slurried with an acetone solution of Co(N03)2~6H20 (0.60
g) and Ruacac3
(4 mg) in a rotary evaporator. The acetone was removed under vacuum at
70°C. The dried material
was calcined at 250°C under 1500 cc/minute of air.
20 The catalyst had a nominal composition of 25 wt. % Co/0.1 wt. % Ru/Si-MCM-
41.
EXAMPLE 7
Example 5A material (0.65 g) was slurried with an aqueous solution of
Co(CH3CO0)2~4H20 (0.4 g) and RuCl3 (1.5 mg) in a rotary evaporator. The water
was removed
under vacuum at 70°C. The dried material was calcined at 250°C
under 1500 cc/minute of air.
25 The catalyst had a nominal composition of 25 wt. % Co/0.1 wt. % Ru/Si-MCM-
41.
EXAMPLE 8
Example 6B material (0.9 g) was slurried with an aqueous solution of
Co(N03)2~6H2O
(0.635 g) and RuCl3 (2 mg) in a rotary evaporator. The water was removed under
vacuum at 70°C.
The dried material was calcined ~t 250°C under 1500 cc/minute of
air.
30 The catalyst had a nominal composition of 25 wt. % Co/0.1 wt. % Ru/Si-MCM-
41.
EXAMPLE 9
Si-MCM)-41 was dried at 200°C for 30 minutes under flowing N2. It was
then mixed
thoroughly with Co2(CO)g (0.2 g) in a glove box. This mixture of solids was
placed into a tube
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furnace boat in a sealed tube and removed from the glove box. It was then
heated in a flow of He at
100°C for 15 minutes, raised to 200°C over 10 minutes, then
heated at 200°C in He for 30 minutes.
The catalyst had a nominal composition of 16 wt. % Co/Si-MCM-41.
EXAMPLE 10
The procedure was identical to that of Example 9 except that the support was
Al-MCM-41.
The catalyst had a nominal composition of 16 wt. % Co/AI-MCM-41.
TABLE 1 (225°C)
Ex. Cll +
No. Catalyst Productivity Alpha
1 Ru(5)/Si-MCM-41 17 0.87
2 Ru(IO~Si-MCM-41 652 0.90
3 Co(25)/Pt(0.08)/Si-MCM-4161 O,gg
4 Co(25)/Pt(0.05)/Si-MCM-4177 0.90
Co(25)/Ru(0.1)/Si-MCM-4134 0.86
6 Co(25)/Ru(0.1)/Si-MCM-41245 0.91
7 Co(25)/Ru(0.1)/Si-MCM-41163 p,g7
8 Co(25)/Ru(O.I~Si-MCM-41244 0.91
9 Co(16)/Si-MCM-41 163 0.86
Co( 16)/AI-MCM-41 214 0.86
While a preferred embodiment of the present invention has been shown and
described, it will
10 be understood that variations can be made to the preferred embodiment
without departing from the
scope of, and which are equivalent to, the present invention. For example, the
structure and
composition of the catalyst can be modified and the process steps can be
varied.
The complete disclosures of all patents, patent documents, and publications
cited herein are
hereby incorporated herein by reference in their entirety. U.S Patent
Application Ser. No.
entitled Fischer-Tropsch Processes Using Xerogel and Aerogel Catalysts, filed
concurrently herewith
on August 18, 1999, and U.S. Patent Application No. , entitled Fischer-Tropsch
Processes
Using Xerogel and Aerogel Catalysts by Destabilizing Aqueous Colloids, filed
concurrently herewith
on August 18, 1999, are hereby incorporated herein by reference in their
entirety.
U.S. Patent Application No. 09/314,921, entitled Fischer-Tropsch Processes and
Catalysts
Using Fluorided Supports, filed May 19, 1999, U.S. Patent Application No.
09/314,920, entitled
Fischer-Tropsch Processes and Catalysts Using Fluorided Alumina Supports,
filed May 19, 1999, and
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U.S. Patent Application No. 09/314,811, entitled Fischer-Tropsch Processes and
Catalysts With
Promoters, filed May 19, 1999, are hereby incorporated herein in their
entirety.
The foregoing detailed description and examples have been given for clarity of
understanding
only. No unnecessary limitations are to be understood therefrom. The invention
is not limited to the
exact details shown and described, for variations obvious to one skilled in
the arl will be included
within the invention by the claims.
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