Note: Descriptions are shown in the official language in which they were submitted.
- lZ5245~
BACKGROUND OF THE INVENTION
I. Field of the Invention
-
This invention relates to improved cobalt
catalysts, and a process for using such catalysts in
the conversion of methanol~ as well as in Fischer-
Tropsch synthesis to produce hydrocarbons, especially
C10+ distillate fuels, and other valuable products.
II. The Prior Art
Methane is often available in large quanti-
ties from process streams either as an undesirable
by-product in admixture with other gases, or as an off
gas component of a process unit, or- units. More
importantly, however, methane is the principal com-
ponent of natural gas, and it is produced in con-
siderable quantities in oil and gas fields. The
existence of large methane, natural gas reserves
coupled with the need to produce premium grade trans-
portation fuels, particularly middle distillate fuels,
creates a large incentive for the development of a new
gas-to-liquids process. Conventional technology,
however, is not entirely adequate for such purpose.
Nonetheless, technology is available for the conversion
of natural gas, to produce methanol, a product of
currently limited market ability. However, to utilize
the existing technology, there is a need for a process
suitable for the conversion of methanol to high quality
transportation fuels, particularly middle distillate
fuels. On the other hand, the technology to convert
natural gas, or methane, to synthesis gas is well
established, and the conversion of the synthesis gas to
hydrocarbons can be carried out via Fischer-Tropsch
synthesis.
~5~5~
Fischer-Tropsch synthesis for the production
of hydrocarbons from carbon monoxide and hydrogen is
now well known in the technical and patent literature.
The first commercial Fischer-Tropsch operation utilized
a cobalt catalyst, though later more active iron
catalysts were also commercialized. An important
advance in Fischer-Tropsch catalysts occurred with the
use of nickel-thoria on kieselguhr in the early
thirties. This catalyst was followed within a year by
the corresponding cobalt catalyst, 100 Co:18 ThO2:100
kieselguhr, parts by weight, and over the next few
years by catalysts constituted to 100 Co:18 ThO2:200
kieselguhr and 100 Co:5 ThO2:8 MgO:200 kieselguhr,
respectively. The Group VIII non-noble metals, iron,
cobalt, and nickel have been widely used in Fischer-
Tropsch reactions, and these metals have been promoted
with various other metals, and supported in various
ways on various substrates. Most commercial experience
has been based on cobalt and iron catalysts. The cobalt
catalysts, however, are of generally low activity
necessitating a multiple staged process, as well as low
synthesis gas throughput. The iron catalysts, on the
other hand, are not really suitable for natural gas
conversion due to the high degree of water gas shift
activity possessed by iron catalysts. Thus, more of
the synthesis gas is converted to carbon dioxide in
accordance with the equation: H2 + 2C0 ~ (CH2)X + C02;
with too little of the synthesis gas being converted to
hydrocarbons and water as in the more desirable
reaction, represented by the equation: 2H2 + C~
(CH2) X + H20-
There exists a need in the art for a process
useful ~or the conversion of methanol and synthesis gas
at high conversion levels, and at high yields to
. - lZSZ4~
-- 3 --
premium grade transportation fuels, especially C1o+
distillate fuels; particularly without the production
of excessive amounts of carbon dioxide.
III~ The Invention
The present invention, in general, embodies:
(A) A particulate catalyst composition
constituted of a catalytically active amount of cobalt,
or cobalt and thoria, to which is added sufficient
rhenium to obtain, at corresponding process conditions,
improved activity and stability in the production oÇ
hydrocarbons from methanol, or in the production of
hydrocarbons via carbon monoxide-hydrogen synthesis
reactions than a catalyst composition otherwise similar
except that it does not contain rhenium. Suitably,
rhenium is added to the cobalt catalyst, or cobalt and
thoria catalyst, in amount sufficient to form a
catalyst having a rhenium:cobalt in weight ratio
greater than about 0.010:1, preferably from about
0.025:1 to about 0.10:1. In terms of absolute con-
centrations, from about 0.05 percent to about 3 percent
of rhenium, preferably from about 0.15 percent to about
l percent of rhenium, based on the total weight of the
catalyst composition (dry basis), is dispersed with the
catalytically active amount of cobalt upon an inorganic
oxide support, preferably upon titania (TiO2~, or a
titania-containing support, particularly titania
wherein the rutile:anatase weight ratio is at least
about 2:3. This ratio is determined in accordance with
ASTM D 3720-78: Standard Test Method for Ratio of
Anatase to RutiIe in Titanium Dioxide Pigments by Use
of X-Ray Diffraction. Suitably, in terms of absolute
concentrations the cobalt is present in the composition
in amounts ranging from about 2 percent to about 25
percentl preferably from about 5 percent to about 15
12S24S;~
-- 4
percent, based on the total weight of the catalyst
composition (dry basis), and sufficient rhenium is
added to form a catalyst having a weight ratio of
rhenium:cobalt greater than about 0.010:1, preferably
from about 0.025:1 to about 0.10:1, based on the total
wei~ht of the cobalt and rhenium contained in the
catalyst composition (dry basis). The absolute
concentration of each metal is, of course, preselected
to provide the desired ratio of rhenium:cobalt, as
heretofore expressed. Thoria can also be added to the
composition, and is preferably added to the catalyst
when it is to be used in the conversion of methanol.
The thoria is dispersed on the support in amounts
ranging from about 0.1 percen~t to about 10 percent,
preferably from about 0.5 percent to about 5 percent,
based on the total weight of the catalyst composition
(dry basis). Suitably, the thoria promoted cobalt
catalyst contains Co and ThO2 in ratio of Co:ThO2
ranging from about 20:1 to about 1:1, preferably from
about 15:1 to about 2:1, based on the weight of the
total amount of Co and ThO2 contained in the catalyst.
These catalyst compositions, it has been found, produce
a product which is predominately Clo+ linear paraffins
and olefins, with very little oxygenates. These
catalysts provide high selectivity, high activity, and
activity maintenance in methanol conversion, or in the
conversion of the carbon monoxide and hydrogen to
distillate fuels. These catalysts are also highly
stable, particularly during high temperature air
regenerations which further extend catalyst life.
(B) A process wherein the particulate
catalyst composition of (A), supra, is formed into a
bed, and the bed of catalyst contacted at reaction
condi~ions with a methanol feed, or feed comprised of
an admixture of carbon monoxide and hydrogen, or
compound decomposable in situ within the bed to
12SZ~S;~
generate carbon monoxide and hydrogen, to produce a
product of middle distillate fuel quality constituted
predominately of linear paraffins and olefins, par-
ticularly Clo+ linear paraffins and olefins.
(i) In conducting the methanol reaction the
partial pressure of methanol within the
reaction mixture is generally maintained
above about 100 pounds per square inch
absolute tpsia), and preferably above about
200 psia. It is preferable to add hydrogen
with the methanol. Suitably methanol, and
hydrogen, are employed in molar ratio of
CH3OH:H2 above abou`t 4:1, and preferably
above 8:1, to increase the concentration of
Clo~ hydrocarbons in the product. Suitably,
the CH3OH:H2 molar ratio, where hydrogen is
employed, ranges from about 4:1 to about
60:1, and preferably the metnanol and
- hydrogen are employed in molar ratio ranging
from about 8:1 to about 30:1. Inlet
hydrogen partial pressures preferably range
below about 80 psia, and more preferably
below about 40 psia; inlet hydrogen partial
pressures preferably ranging from about 5
psia to about 80 psia, and more preferably
from about 10 psia to about 40 psia. In
general, the reaction is carried out at
liquid hourly space velocities ranging from
about 0.1 hr~l to about 10 hr~l, preferably
from about 0.2 hr~l to about 2 hr~l, and at
temperatures ranging from about 150C to
about 350C, preferably from about 180C to
about 250C. Methanol partial pressures
preferably range from about 100 psia to
about 1000 psia, more preferably from about
200 psia to about 700 psia.
--`` ;12SZ45;~ . -
-- 6 --
(ii) In general, the synthesis reaction is
carried out at an H2:CO mole ratio of
greater than about 0.5, and preferably the
H2:CO mole ratio ranges from about 0.1 to
about 10, more preferably from about 0.5 to
about 4, at gas hourly space velocities
ranging from about 100 V/Hr/V to about 5000
V/Hr/V, preferably from about 300 V/Hr/V to
about 1500 V/Hr/V, at temperatures ranging
from about 1~0C to about 290C, preferably
from about 190C to about 260C, and
pressures above about 80 psig, preferably
ranging from about 80 psig to about 600
psig, more preferably from about 140 psig to
about 400 psig. In its most preferred form,
a bed of catalyst comprised of from about 5
percent to about 15 percent cobalt, con-
taining sufficient rhenium to provide a
~ ~ catalyst containing rhenium:cobalt in ratio
ranging from about 0.025:1 to about 0.10:1,
is dispersed on titania, preferably a high
purity titania, and a bed of such catalyst
is contacted with a gaseous admixture of
carbon monoxide and hydrogen, or compound
decomposable in situ within the bed to
generate carbon monoxide and hydrogen.
The product of either the methanol conversion reaction,
or synthesis reaction generally and preferably contains
60 percent, more preferably 75 percent or greater, C10+
liquid hydrocarbons which boil above 160C (320F).
It is found that cobalt and rhenium, or
cobalt, thoria and rhenium, supported on titania, or
other titania-containing support provides a catalyst
system which exhibits superior methanol conversion, or
125;~5;~
hydrocarbon synthesis characteristics in Fischer-
Tropsch reactions. The titania-containing supports
used in the practice of this invention are preferably
oxides having surface areas of from about 1 to about
120 m2g~l, preferably from about 10 to about 60 m2g~l.
Rhenium-cobalt/titania and rhenium-thoria-
cobalt/titania catalysts exhibit high selectivity in
the conversion of methanol to hydrocarbon liquids, or
synthesis of hydrocarbon liquids from carbon monoxide
and hydrogen. The catalysts employed in the practice
of this invention may be prepared by techniques known
in the art for the preparation of other catalysts.- The
catalyst can, e.g., be prepared by gellation, or
cogellation techniques. Suitably, however, the metals
can be deposited on a previously pilled, pelleted,
beaded, extruded, or sieved support material by the
impregnation method. In preparing catalysts, the
metals are deposited from solution on the support in
preselected amounts to provide the desired absolute
amounts, and weight ratio of the respective metals, or
cobalt, rhenium, and thoria. Suitably, the cobalt and
rhenium are composited with the support by contacting
the support with a solution of a cobalt-containing
compound, or salt, or a rhenium-containing compound, or
salt, e.g., a nitrate, carbonate or the like. The
thoria, where thoria is to be added, can then be
composited with the support as a thorium compound or
salt in similar manner, or the thorium can first be
impregnated upon the support, followed by impregnation
of the cobalt, or rhenium, or both. Optionally, the
thorium and cobalt, or thoria, cobalt, and rhenium can
be co-impregnated upon the support The cobalt,
rhenium and thorium compounds used in the impregnation
can be any organometallic or inorganic compounds which
decompose to give cobalt, rhenium, and thorium oxides
upon calcination, such as a cobalt, rhenium, or thorium
lZ5~45;~
nitrate, acetate, acetylacetonate, naphthenate,
carbonyl, or the like. The amount of impregnation
solution used should be sufficient to completely
immerse the carrier, usually within the range from
about 1 to 20 times of the carrier by volume, depending
on the metal, or metals, concentration in the im-
pregnation solution. The impregnation treatment can be
carried out under a wide range of conditions including
ambient or elevated temperatures. Metal components
other than rhenium and cobalt tor rhenium, cobalt and
thorium) can also be added. The introduction of an
additional metal, or metals, into the catalyst can be
carried out by any method and at any time of the
catalyst preparation, for example, prior to, Eollowing
or simultaneously with the impregnation of the support
with the cobalt and rhenium components. In the usual
operation, the additional component is introduced
simultaneously with the incorporation of the cobalt and
rhenium, or cobalt, rhenium, and thorium components.
-
Titania is used as a support, or in com-
bination with other materials for forming a support.
The titania used for the support in either methanol or
syngas conversions, however, is preEerably one where
the rutile:anatase ratio is at least about 2:3 as
determined by x-ray diffraction (ASTM D 3720-78).
Preferably, the titania used for the catalyst support
of catalysts used in syngas conversion is one wherein
the rutile:anatase ratio is at least about 3:2.
Suitably the titania used for syngas conversions is one
containing a rutile:anatase ratio of Erom about 3:2 to
about 100:1, or higher, preferably from about 4:1 to
about 100:1, or higher. A preferred, and more
selective catalyst for use in methanol conversion
reactions is one containing titania wherein the
rutile:anatase ranges from about 2:3 to about 3:2. The
surface area of such forms of titania are less than
12~245;~
about 50 m2/g. This weight of rutile provides
generally optimum activity, and Clo+ hydrocarbon
selectivity without significant gas and CO2 make.
The catalyst, after impregnation, is dried
by heating at a temperature above about 30C,
preferably between 30C and 125C, in the presence of
nitrogen or oxygen, or botb, or air, in a gas stream or
under vacuum. It is necessary to activate the cobalt-
titania, or tboria promoted cobalt-titania catalyst
prior to use. Preferably, the catalyst is contacted
with oxygen, air, or other oxygen-containing gas at
temperature sufficient to oxidize the cobalt, and
convert the cobalt to Co3O4. Temperatures ranging
above about 150C, and preferably above about 200C are
satisfactory to convert the cobalt to the oxide, but
temperatures up to about 500C such as might be used in
the regeneration of a severely deactivated catalyst,
can generally be tolerated. Suitably, the o~idation of
the-cobalt is achieved at temperatures ranging from
about lS0C to about 300C. The cobalt, or cobalt and
rhenium metals contained on the catalyst are then
reduced. Reduction is performed by contact o~ the
catalyst, whether or not previously oxidized with a
reducing gas, suitably with hydrogen or a hydrogen-
containing gas stream at temperatures, above about
250C; preferably above about 300C. Suitably, the
catalyst is reduced at temperatures ranging from about
250C to about 500C, and preferably from about 300C
to about 450C, for periods ranging from about 0.5 to
about 24 hours at pressures ranging from ambient to
about 40 atmospheres. Hydrogen, or a gas containing
hydrogen and inert components in admixture is satis-
factory for use in carrying out the reduction.
245;~
-- 10 --
If it is necessary to remove coke from the
catalyst, the catalyst can be contacted with a dilute
oxygen-containing gas and the coke burned from the
catalyst at controlled temperature below the sintering
temperature of the catalyst. The temperature of the
burn is controlled by controlling the oxygen con-
centration and inlet gas temperature, this taking into
consideration the amount of coke to be removed and the
time desired to complete the burn. Generally, the
catalyst is treated with a gas having an oxygen partial
pressure of at least about 0.1 psi, and preferably in
the range of from about 0.3 psi to about 2.0 psi to
provide a temperature ranging from about 300C to about
550C, at static or dynamic conditions, preferably the
latter, for a time sufficient to remove the coke
deposits. Coke burn-off can be accomplished by first
introducing only enough oxygen to initiate the burn
while maintaining a temperature on the low side of this
range, and gradually increasing the temperature as the
flame front is advanced by additional oxygen injection
until the temperature has reached optimum. Most of the
coke can be readily removed in this way. The catalyst
is then reactivated, reduced, and made ready for use by
treatment with hydrogen or hydrogen-containing gas as
with a fresh catalyst.
The invention will be more fully understood
by reference to the following demonstrations and
examples which present comparative data illustrating
its more salient features. All parts are given in
terms of weight except as otherwise specified. Feed
compositions are expressed as molar ratios of the
components.
The "Schulz-Flory Alpha" is a known method
for describing the product distribution in Fischer-
Tropsch synthesis reactions. The Schulz-Flory Alpha is
-- 11 --
the ratio of the rate of chain propagation to the rate
of propagation plus termination, and is described from
the plot of ln (Wn/n) versus n, where Wn is the weight
~raction of product with a carbon number of n. In the
examples below, an Alpha value was derived from the
Clo/C20 portion of the product. The Alpha value is
thus indicative of the selectivity of the catalyst for
producing heavy hydrocarbons from the synthesis gas,
and is indicative of the approximate amount of Clo+
hydrocarbons in the product. For example, a Schulz-
Flory Alpha of 0.80 corresponds to about 35% by weight
of Clo+ hydrocarbons in the product, a generally
acceptable level o Clo+ hydrocarbons. A Schulz-Flory
Alpha of 0.~5, a preferred Alpha value, corresponds to
about 54% by weight of Clo+ hydrocarbons in the
products, and a Schulz-Flory Alpha of 0.90, a more
preferred Alpha value, corresponds to about 74% by
weight of C10+ hydrocarbons in the product.
- The following data show that the addition of
a small amount of rhenium to a Co-TiO2 catalyst
maintains the cobalt in a high state of dispersion and
stabilizes the ca~alyst during high temperature air
treatment. The rhenium thus maintains the very high
activity of the catalyst which is characteristic of one
having well-dispersed cobalt on the Tio2. The high
activity of Co-Re-TiO2 permits high conversion opera-
tions at low temperature where excellent selectivity is
obtained in the conversion of syngas to Clo+ hydro-
carbons.
EXAMPLE 1
Titania (Degussa P-2~ TiO2) was used as the
support for all of the catalysts after mixing with
Sterotex*(a vegetable stearine used as a lubricant and
a product of Capital City Products Co., Columbus,
*Trademark
SZ~S'~
Ohio), and after pilling, grinding, and screening to
either 60-150 mesh or 16-20 mesh tTyler)- Two versions
of TiO2 were prepared by calcining portions of the TiO2
in air at 500C and 600C, respectively, overnight.
Tbis gave TiO2 supports with the following properties:
~U~C ~160
Calc~nat~o~ Rut~ Anata~ A~a -Po~e Voluma
TQ~p~r~tu~, C ~ ~ =l/q
S00 1.2sl-131 33 - 36 0.28 - 0.40
~00 >30sl 10 - 16 0.11 - 0.15
., . . _ . . .. ...
(1) AS~M D 3720-78.
Catalysts, of 16-20 mesh size, were prepared from
selected portions of these materials by simple impreg-
nation of the support with cobaltous nitrate or
perrhenic acid, or both, from acetone solution using a
rotary evaporator, drying in a vacuum oven at 150C,
and calcining of the catalysts for three hours in
flowins air in a quartz tube. The catalysts,
identified in the second column of Table I, were
charged to a reactor, reduced in H2 at 450C for one
hour, and then reacted with syngas at 200C, 280 psig,
GHSV = 1000, and H2:CO = 2.15 for at least 16 hours.
The performance of each catalyst was monitored by
conventional GC analysis using neon as an internal
standard (4% in the feed). Screening results for these
catalysts and dynamic 2 chemisorption data are given
in Table I. Reference is also made to Figure 1 which
graphically depicts the data obtained with most of
these catalysts, the percent CO conversion being
plotted against the percent rutile contained in the
Ti~2 support, the rutile:anatase ratio being expressed
in both Table I and Figure 1 as percent rutile to
facilitate construction of the graph.
lZ~2~S'~
T BL~ IA
280C, 280 p9ig, G8SV - 1000, H2:C0 ~ 2.~5
~t. ~ 2 Che~i-
~tal~ cn 30~ptlon ~ C
~un 16- 20 Me~h ~ Rutll~ Alr T~eat Y mol 2/9 Conver-
NoO ~ ~ C ~3 hr.1 ~ 3ion
1 12 Co 53(1) 250 213 67
2 12 Co 100~2) 250 2~5 79
3 12 Co 56(3) 500 178 54
4 12 Co 100(2) 5~0. 202 67
12 Co-3 Re 56~3) 500 399 81
6 12 Co-.5 Re 100( ) 500 285 . 82
7 12 Co-.l Ro 10~(2) 500 145 67
8 12 Co-.5 R~ 56 3) 500 343 85
3 R~ 56(3) 500 149 <1
(1) ~utllc;AnatasQ ratio 1.1:1.
(2) Rutila:Anatas~ ratio >30:1.
(3) Rutlla:Anatasc ratio 1.3:1.
- Reference is made to the intermediate curve
plotted on Figure 1 which is representative of the data
obtained from runs 1 and 2, of Table I representing an
unpromoted 12~ Co catalyst the TiO2 support having a
rutile :anatase ratio of 1.1:1 (53% rutile content),
and another unpromoted 12~ Co catalyst the support of
which has a rutile:anatase ratio >30:1. The
rutile:anatase ratio, as suggested, has been expressed
in Figure 1 as percentages for convenience of ex-
pression, or to facilitate construction of the graph.
Both catalysts represented on the graph by circled
dots, were calcined in air at 250C~ Clearly the
catalyst having the high rutile TiO2 support is the
superior catalyst providing 79~ CO conversion vis-a-vis
67~ CO conversion obtained by use of the catalyst
having the lower rutile content TiO2 support. Re-
ferring now to the bottom curve on the figure, there is
shown a plot representative of data obtained from runs
lZ~Z45;Z
- 14 -
3 and 4, viz., runs made with unpromoted cobalt
catalysts similar to those employed in runs 1 and 2,
respectively, except that in these instances both
catalysts were calcined in air at 500C. These
ca~alysts are also represented on the graph by circled
dots. The unstabilized cobalt catalysts (as shown by a
comparison of the activities of the catalysts used in
runs 3 and 4, vis-a-vis those used in runs 1 and 2)
both show a drop in activity due to the calclnation in
air at 500C, which caused cobalt agglomeration, or
loss of cobalt dispersion. The cobalt catalyst formed
from a high rutile Tio2 support is clearly the superior
catalyst, the cobalt being more highly dispersed on the
high rutile support.
Reference is again made to Figure 1, runs 5,
6, and 8 (represented by black dots) being plotted as
the top curve of the graphical data presented. Run 5
was made with a 12% Co-3% Re-TiO2 (56~ rutile), run 6
with a 12~ Co-0.5 Re-TiO2 (100% rutile), and run 8 with
a 12% Co-0.5~ Re-TiO2 (56% rutile). These three
catalysts were calcined in air at 500C. These data
clearly show that the rhenium was adequate to stabilize
the cobalt metal on both of the catalysts against
agglomeration, or loss of cobalt dispersion. A 0.5~
level of rhenium is sufficient to stabilize the 12~ Co
catalyst (Runs 6 and 8) against loss of cobalt metal
dispersion, it being noted that the rhenium promoted
cobalt catalyst (Runs 5, 6, or 8) is at least the
equivalent of or superior to the unpromoted cobalt
catalyst wherein the cobalt is dispersed on a 100% TiO2
rutile base.
Catalysts which contain at least 0.5% Re, as
shown by the data, provide consistently high activity
after 500C calcination regardless of rutile content.
In general, there is no significant benefit
lZ~5'~:
obtained by adding a greater amount of rhenium. A 0.1
wt. ~ rhenium level, however, is inadequate to fully
protect a 12% Co catalyst. Note that the rhenium
promoted Co catalyst, 12% Co-0.1% Re catalyst (Run 7),
is mildly agglomerated after contact with air at 500C.
These activity data can also be expressed as
a pseudo first order rate constant, k, represented by
the equation
k = p ln (l-X)
where X = fraction CO conversion, P = reactor pressure,
atm., and GHSV = space velocity at ambient T and P,
hr~l A plot of k versus ~ mol O2~g catalyst,
determined by conventional dynamic 2 chemisorption, is
shown by reference to Figure 2. Note that for the
Co-Re catalysts the contribution of Re 2 chemisorption
has been subtracted out of the total chemisorption
value to obtain a chemisorption value for the cobalt
component. The data fall on a straightline correlation
thus indicating that the activity of all of these
catalysts is a direct function of the cobalt dis-
persion. Rhenium promoted catalysts show the highest
activity because they possess the highest cobalt
dispersion. Such catalysts are also quite stable and
have strongly resisted agglomeration during the 500C
calcinations.
EXAMPLE 2
The surprisingly high activity of a
Co-Re-TiO2 catalyst is further demonstrated by a
comparison of the 12~ Co-0.5% Re-TiO2 catalyst (100%
rutile TiO2) of Example 1 with a Ru-Tio2 catalyst, a
known high activity catalyst.
1'2~:~'Z~5'~
- 16 -
A 60-150 mesh granulated 12~ Co-0.5% Re-TiO2 ~100%
rutile) catalyst was charged to a reactor, and con-
tacted with a syngas having an H2:CO ratio of about 2
to 2.15 at 200C, 280 psig, and GHSV = 1000 for a
period ranging up to 190 hours. For comparative
purposes, a similar run was subsequently made with a
80-150 mesh ~ranulated 1% Ru-TiO2 ~73~ rutile; or 2.7:1
rutile:anatase) catalyst. Readings were taken at
certain intervals, and the product stream analyzed to
determine the wt.~ CO conversion, and mol.
selectivity to CH4, CO2, C2+ and the Schulz-Flory
Alpha. Reference is made to Table II.
TA~,E ~I
200^C, 290 p~i9, G~SV ~ 1000, H2/C0 ~ 2.0W2.1S
12~ Co 0.5~ Re-TiO2
60-150 me~h, 1~ Ru-TiO2
Calcin~d 500C 80 lS0 h-sh
~our~ on S~rcam 15 75 190 4 162
CO Conver910n, wt. ~ 98 86 78 45 22
~ol. ~ S~l~c~vity
C~4 4.5 3.5 3.3 2.3 5.2
C2 2.3 0.6 0.3 2.3 _ 0.1
C2~ 93.2 95.9 96.4 95.4 94.7
Schulz-Flory Alpha -- 0.92 0.92 --
.
As shown by the data, the 12% Co-0.5~
Re-TiO2 catalyst is far more active than the 1~ Ru-TiO2
catalyst at 200C, and is capable of providing high CO
conversion and high selectivity to heavy hydrocarbons
as indicated by the low CH4+, CO2 by-product yields and
high Schulz-Flory Alpha.
- 12S~4S'~
- 17 -
The results of the continuous 190 hour run
presented in Table II are graphically illustrated in
Figure 3. This high conversion run produced a very
heavy hydrocarbon product consisting principally of
linear paraffins with some linear olefins and branched
components. The Schulz-~lory Alpha was 0.92,
indicative of about ~0 wt.% Clo~ hydrocarbons in the
product.
During the course of the continuous runs,
gas hourly space velocity was varied in order to obtain
data at various levels of CO conversion. The results
comparing the Co-Re-TiO2 catalyst with the Ru-Tio2
catalyst are graphically depicted in Figures 4 and 5.
As shown in Figure 4, the 12% Co-.5% Re-TiO2 catalyst
is far more active than the 1% Ru-TiO2 catalyst at
200C, as determined by the higher conversion at a
given space velocity. The selectivity for CH4 and CO2
is quite low for both of these catalysts as depicted by
reference to Figure 5.
EXAMPLE 3
Rhenium promoted cobalt catalysts are also
very active for the conversion of methanol to hydro-
carbons. For purpose of illustration, a series of runs
were made with three cobalt catalysts, viz., (1) 12~
Co-2% ThO2/TiO2, (2) 12% Co-2% ThO2-0.5% Re/TiO2, and
(3) 12~ Co-0.5 Re/TiO2, formed by impregnation of
16-20 mesh TiO2 (56% rutile). Each catalyst was
charged to the reactor and air calcined at 500C. In
conducting the runs, methanol, with argon, was passed
over each of the catalysts at 230C, 400 psig, GHSV =
500, and CH3OH/Ar = 4 with the results obtained by
reference to Table III.
~ ` 12~2 ~S;~
TABL ~
~ethanol Conver~lon
230C, 400 psig~ GHSV D 50O~ C~30~/Ar ~ 4
(16-20 Mesh Ca~aly~ts, Calclned S00C)
.
12~ Co -
12~ Co 2~ ThO2 - 12~ Co -
2~ ThO2- S~Q 0.5~ ~e
CH30H Conver~ion 49 100 87
Carbon P~duct
DiRtribution, Wt. ~
C0 6 2 2
C2 14 28 22
c~4 6 ~ 14 g
C2~ 74 56 67
.
These data clearly show that the Co-Re-TiO2
and Co-ThO2-Re-TiO2 catalysts provide high levels of
conversion compared to the unpromoted Co-ThO2-TiO2
cata}yst, a preferred catalyst for this reaction,
although selectivities to C2+ hydrocarbons in each
instance is debited to some extent by a high C02 make.
This high water gas shift activity with methanol is not
observed with a syngas feed.
The following data show that the cobalt
catalysts are activated for syngas conversion by
reducing the cobalt prior to use of the catalyst for
the conversion of syngas to hydrocarbons.
--` 3.Z52~5~
-- 19 --
EXAMPLE 4
A series of runs were made at similar
conditions with portions of a Co-TiO2 catalyst (12
Co-0.53 Re/TiO2 ~100~ rutile) after pretreatment of the
different portions for three hours with hydrogen at
200C, 235C, 300C, and 4S0C, respectively. The runs
were carried out by contact of the catalysts, in
different runs at 200C, 280 psig, GHSV = 1000 and
H2:CO = 2.15, with a synthesis gas comprised of an
admixture of hydrogen and carbon monoxide. The results
are given in Table IV.
TA3LE rv
12~ Co-0.5~ Re Rutlle, 60-150 Mesh, Calc~n~d 500C - 3 Hr
200C, 280.psig, GHSV ~ 1000, H2/CO - 2015
Raduction TemporaturQ! C CO Convers~on
200 0
235 8
300 98
450 99
~ -- . .. . . .
The~results show that the high temperature
reduction is necessary to activate the catalyst for
conversion of syngas. Reduction of the cobalt above
about 250C, and preferably above about 300C, is
necessary. Suitably, the reduction is carried out at
temperatures ranging from about 250C to about
500 C, and preferably from about 300C to about 450C,
with hydrogen or a hydrogen-containing gas.
