Note: Descriptions are shown in the official language in which they were submitted.
~3~
-- 1 --
1 BACKGROUND OF THE I~VENTION
2 1. Field of the Invention
3 This invention relates to a Fischer-Tropsch
4 process for selectivity producing low molecular wei~ht
5 alpha-olefins utilizing an unsupported single phase
6 Ee-Mn spinel catalyst promoted with Group IA or IIA
7 metal salt in which the atomic ratio of Fe:Mn is 2:1 or
8 above.
9 2. Brief Description of the Prior ~rt
Fischer-Tropsch processes have long been
11 known to produce gaseous and liquid hydrocarbons con-
12 taining C2-C4 olefins. Because of the importance of
13 C2-C4 olefins, particularly as feedstocks for the
14 chemical industry, modifications of the Fischer-Tropsch
15 process are constantly being pursued toward the goals
16 of maximizing C2-C4 olefin selectivity with the
17 particular objective of maintaining high catal~st
18 activity and stability under the reaction conditions.
19 The main thrust of the efforts in this area has been in
20 the area of cataIyst formulation.
21 Coprecipitated and/or supported iron-based
22 catalysts, including those containing manganese, ~re
23 known for producing C2-C4 olefins. Examples of
24 disclosures in the art directed to such iron-manganese
25 catalysts and/or alloys include: W.L. vanDijk, et al.,
26 Appl. Catal., 2, 273 (1982); Eur. Pat. Appl. 4988~ to
27 ~uhrchemie (1981); H.J. Lehman, 73rd AIChe Meeting
-- 2
1 Paper #103D; W.D. Deckwer, et al., Chem. In~. Tech., 53
2 (10), 818 (1981); V. Rao and R. Gormley, Hydrocarbon
3 Processing, l , November (1981); H. Kolbel and K.
4 Tillmetz, U.S. Pat. 4,177,203 (1970); EPO Patent Pub-
5 lication 0,071,770; U.S. Patent 2,605,275; U.S. Patent
6 2,850,515; Prepr. Div. Pet. Chem. Am~ Chem. Soc. (1978)
7 23(2) pp 513-20; Intersoc. Energy Convers. Eng. Conf.
8 1978, 13(1) pp 482-6; U.S. Patent 4,186,112; EP 49,888;
g React. Kinet. Catal. Lett. 1982, 20(1-2) pp 175-~0;
10 U.S. Patent 2~778,845; Khim. (1) Tekhnol~ Topliv i
11 Masel (Russ.) 10(6) 5-10 (1965); UK Patent Appln.
12 2,050,859 A; German Patent Appln. DT 2919-921; Prace
13 Ustavu Vyzkum Paliv 8, p. 39-81 (1964) (Czech).
_
14 An iron-manganese spinel of the formula,
15 Fe2MnO4, is reported as a catalyst component formed
16 during Fischer-Tropsch synthesis in which a coprecip-
17 itated Fe/Mn oxide catalyst is initially employed in
18 Applied Catalysis 5 (1983) pp. 151-170. However, this
19 and the above cited references do not describe a
20 Fischer-Tropsch hydrocarbon process initially employing
21 an unsupported single phase Fe/Mn spinel catalyst
22 having an Fe:Mn atomic ratio of 2:1 or above and being
23 promoted with a Group IA or IIA metal salt promoter
24 agent.
What is particularly desired in fixed bed
26 Fischer-Tropsch processes are catalysts for selectively
27 producing high levels of C2-C4 olefins and low levels
28 Of methane under the desirable combined conditions of
29 high catalyst activity and stability.
- - ~ ~
~3~2~i
1 SUMMARY OF THE INVENT
2 It has been found that unsupported single
3 phase iron-manganese spinels containing iron:manganese
4 atomic ratios of 2:1 or above and being preferably
5 promoted with a Group IA or IIA metal salt, preferably
6 being substantially deposited on the surface of said
7 spinel provide desirable catalyst properties in fixed
8 bed Fischer-Tropsch processes. The initial spinels
g prior to reduction and carbiding exhibit an X-ray
10 diffraction pattern isostructural with Fe3O4.
11 The subject spinels are prepared in a high
12 temperature solid state sintering reaction in a tem-
13 perature range of about 600 to 110nC between the
14 component metal oxides and/or metals and mixtures
15 thereof, in an inert oxygen-free atmosphere or under
16 vacuum. The spinels prepared in this manner can then
17 be treated by surface impregnation or deposition with
18 promoter agents, particularly Group IA and Group IIA
19 metal salts, and particularly, potassium carbonate and
20 potassium sulfate. The resulting iron/potassium atomic
21 ratio is desirably in the range of about 20:1 to 200:1.
22 The promoted catalyst can then be partially reduced by
23 contacting with a hydrogen containing gas and partially
24 carbided in a CO-containing atmosphere before use in
25 the Fischer-Tropsch process. By the terms "partially
26 reduced" and "partially carbided" is meant that the
27 iron "portion" of the spinel remains substantially as
28 the oxide.
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1 In accordance with this invention there is
2 provided a hydrocarbon synthesis catalyst composition
3 comprising an unsupported Group IA or IIA metal salt
4 promoted iron-manganese single phase spinel, said
5 spinel having the initial empirical foemula:
6 FexMnyO4
7 wherein x and y are inte~er or decimal values, other
8 than zero, with the proviso that the s~m of x I y is 3
9 and the ratio of x/y is 2:1 or above, said spinel
10 exhibiting a powder X-ray diffraction pattern
11 substantially isostructural with Fe304 and said metal
12 salt being substantially deposited o~ the surface of
13 said spinelO
14 Preferred embodiments of the composition
include the parti~.ily reduced and carbided form of the
16 spinel, which is an active Fischer-T~opsch catalyst in
17~fixed bed process for producing low molecular weight
18 olefins.
19 Furthermore, there is provided a process for
producing the above-~escribed spinel portion of the
21 composition comprising heating a mixture of iron and
22 manganese as their oxides and/or free metals at
23 elevated temperature in an oxygen free or inert
24 atmosphere for a sufficient time until the resulting
oxide mixture exhibits an X-ray diffraction pattern
26 isostructural with Fe3O4.
3~
--5--
S~ecifically, and in accordance wi~h ~his invention
there i8 erovided a process for syn~hesizing a hydcocarbon mixture
containing Cz-C6 olefin~ comp~i~ing the step of contacting a
catalyst composition comprised of an unsupported iron-mangane~e
spinel, fiaid spinel exhibiting a single spinel pha~e, being
isostructural with FE304 as determined by X-ray diffractomet~y.
and pos6es~ing an iron:manganese atomic catio o~ 2:1 to 19:1, 6aid
~pinel being ~urface impregnated or deposited with a potas~ium
salt, ehe atomic ~atio of iron:potassium bei~g about 20:1 to
200:1, with a mixture of C0/H2 unde~ proces6 condition6 of
pres~ure, space ~elocity (SHSV) and elevated te~perature fo~
time su~f icient to produce said C2-C6 olef ins .
DESC2IPTION OF THE INVENTION AND PREFERRED EMBODIMENTS
The subject unsupported alkali- or alkaline
earth metal salt promoted iron-manganese single phase
spinels are new compositions of matter which are iso-
structural with Fe~04, as determined by x-ray
diffractometry using copper K alpha radiation and
exhibit,a single spinel phase. By the term "spinel" is
meant a crystal structure whose general stoichiometry
corresponds to AB204, where A and B can be the same or
different cations. Included within this definition is
the commonly found spinel, MgAl204, A and B can have
the following cationic charge combinations: A=~2, B=+3,
A=+4, s=+2, or A=+6, B=+l. Spinels contain an approx-
imately cubic close-packed arrangement of oxygen atoms
1 with 1/8th of the available tetrahedral interstices and
2 1/2 of the octahedral interstices filled, and can
3 exhibit hundreds of different phases. Further descrip-
4 tion of the spinel structure can be found in
5 "Struc-tural Inorganic Chemistry "by A. F. Wells, Third
6 Edition, Oxford Press, and the Article "Crystal
7 Chemistry and Some Magnetic Properties of Mixed Metal
8 Oxides with the Spinel Structure" by G. Blasse,
9 Phillips Research Review Supplement, Volume 3, pp 1-30,
(1964). By the term "isostructural" is meant crystal-
11 lizing in the same general structure type such that the
12 arrangement of the atoms remains very similar with only
13 minor change in unit cell constants, bond energies and
14 angles. By the term "single phase spinel", as used
15 herein, is meant one structural and compositional
16 formula, corresponding to a single spinel material into
17 which all of the metal components are incorporated, and
18 exhibiting one characteristic X-ray diffraction
19 pattern.
The subject iron-manganese spinels generally
21 possesses a BET surface area up to about 5 m2/g, as
22 determined by the well-known BET surface area measure-
23 ment technique as described in the reference JACS 60,
24 p.309 (1938) by S. Brunauer, P.H. Emmett, and
25 G. Teller. Preferably, the spinel has a surface area
26 of about 0.1 to 5 m2/g. This range of surface area
27 generally corresponds to a particle size range of about
28 1 to 10 microns.
29 The spinel can be represented by the
30 formula: FexMnyO~, wherein x and y are decimal or
31 integer values, other than zero, and wherein the sum of
32 x plus y is 3, and the ratio of x to y is greater than
33 2:1 or above, and preferably being about 2:1 to 19:1
34 and particularly preferred is where the iron to
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1 manganese atomic ratio is about 3:1 to 7:1. The com-
2 position can further be comprised of a mixture of
3 single phase spinels, of different iron-manganese
4 atomic ratios.
Representative examples of the various
6 spinels corresponding to the Eormula are
7 Fe2.85Mn0.154r Fe~.625Mn0.3754, Fe2 25Mno 754
8 Fe2.g7MnQ.03O4-
.
9 Physical properties in general of these10 subject spinels are similar to those of magnetite and
11 include melting point of above 1400C, and a color of
12 brownish-red.
13 The iron-manganese spinels are used in
14 unsupported form in H2/CO hydrocarbon synthesis.
A Group IA alkali metal or Group IIA
16 alkaline earth metal salt promoter agent is used in
17 the subject composition and can also be used to par-
18 ticularly promote olefin formation in the subject
19 process. Representative examples of suitable classes
20 of promoter agents include carbonates, bicarbonates,
21 organic acid and inorganic acid salts e.g. acetates,
22 nitrates, halides, sulfates, and hydroxide salts of
23 Group IA and IIA metals including lithium, sodium,
24 potassium, cesium, rubidium, barium, strontium, mag-
25 nesium and the like.
26 Representative examples of specific promoter
27 agents are potassium carbonate, potassium sulfate,
28 potassium bicarbonate, cesium chloride, rubidium
29 nitrate, lithium acetate, potassium hydroxide, and the
30 like. Preferred are the Group IA compounds and a par-
31 ticularly preferred promoter agent is potassium
~3~6
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1 carbonate. The promoter, if used, is generally prese~t
2 in about a 0.1 to 10 gram-atom ~ of the total gram-
3 atoms of metals present. A preferred level of promoter
4 agent is in the range of 1 to 2 gram-atom % of the
5 total gram-atom metal present. In the empirical
6 formulas used herein, the amount of the promoter agent,
7 e.g., potassium, is expressed in terms of gram atom
8 percent based on the total gram-atoms of metals used.
9 Thus, "1 gram-atom percent of potassium signifies the
10 presence of 1 gram-atom of potassium per 100 total gram
11 atoms of combined gram atoms of Fe and Mn. Thus, the
12 symbol "/1% K" as used herein indicates 1 gram-atom
13 percent potassium based on each 100 gram atom of the
14 total gram atom of iron and manganese present.
A particularly preferred spinel compositi~n
16 of the subject invention is Fe2.2sMno 7sO4/1% K. The
17 catalyst spinel in the subject process may also be used
18 in conjunction with a diluent material, one which ai~s
19 in heat transfer and removal from the catalyst be~.
20 Suitable materials include powdered quartz, silicon
21 carbide, powdered borosilicate glass, kieselguhr,
22 zeolites, talc, clays, Group II-VII oxides and rare
23 earth oxides including TiO2, SiO2, A12O3, MgO, La2O3,
24 CeO2, Cr2O3, MnO2 and the like.
The diluent, if used, is generally used in a
26 1:4 to 9:1 diluent/spinel composition weight ratio to
27 the spinel. Preferred is a 1:1 weight ratio.
28 The utility of these spinels is their
29 ability upon subsequent reduction and carbiding to fo~m
30 active catalysts in a fixed bed Fisher-Tropsch process
31 for making C2-C6 olefins from CO/hydrogen.
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1 The partially reduced and carbided forms of
2 the above-described spinel are also subjects of this
3 invention.
4 The subject spinel is prepared by a solid
5 state high temperature reaction between (1) the com-
6 ponent oxides, iOe. Fe3O4 and Mn3O4l or (2) a mixture
7 of iron metal, manganese oxide and iron oxide, iOe. Fe,
8 Mn3O4 and Fe2O3 or (3) a mixture of manganese metal,
9 iron oxide and manganese oxide, i.e. Mn, Fe3O4, Fe2O3
10 and Mn3O4, or (4) a mixture of iron and manganese
11 metals, iron oxide and manganese oxide, i.e., Fe, Mn,
12 Fe2O3 and Mn3O4, in the empirical formula Eor the
13 composition formula as given above. Preferred is
14 reaction (2) described above. The reaction is con-
15 ducted at temperatures in the range of about 600 to
16 1100C and preferably from about 800 to 1000C, in an
17 inert gas, oxygen-free atmosphere or vacuum environ-
18 ment. Example of useful inert gases are heliu~,
19 nitrogen, argon, and the like. The solid state hi~h
20 temperature reaction "sintering" should be performed on
21 thoroughly mixed samples of the metal oxides and/or
22 metal and metal oxide mixtures. Preferred method of
23 forming the mixture is by intimate grinding. The
24 sintering reaction should be conducted until an X-ray
25 diffraction pattern indicates a single spinel phase is
26 formed which generally requires about an 8 to 24 hour
27 period and preferably about 12 to 18 hour period.
28 Generally, at the end of each reaction period material
29 is thoroughly ground and mixed and then resubjectea to
30 the high temperature conditions for an additional 1 to
31 5 cycles or until X-ray diffraction reveals the
32 presence of a single spinel phase.
-- 10 --
1 Prior to the hydrocarbon synthesis run the
2 iron-manganese spinel is conditioned by treating in a
3 reducing atmosphere at elevated temperature, generally
in a temperature range of about 200 to 500C and
5 preferably 350 to 450C. The treatment can be carried
6 out with various reducing gases including hydrogen,
7 hydrogen/CO and the like, and mixtures thereof.
8 Preferably, hydrogen gas, either by itself or in an
g inert carrier medium such as helium neon, argon, or
10 nitrogen, is preferably used. The pressure of the
11 reducing gas in this procedure may be in the range of
12 1.5 to 1000 psig and preferably in the range of 15 to
13 150 psig. The reducing gas feed rate may be in the
14 ranqe of 1-10,000 V/V/hr and preferably in the range of
15 10-1000 V/V/hr. A preferred method of totally reducing
16 the Fe-Mn spinel is described in copending S~ (C-1544),
17 in which the spinel is heated with metallic calcium to
18 substantially form Fe Mn alloy after acid leaching.
19 The resulting partially reduced spinel is
20 useful in the subject Fischer-Tropsch process for
21 making C2 to C6 olefins as described herein, after
22 being treated in a suitable carbiding atmosphere.
23 Suitable carbiding atmospheres include CO,
24 CO/H2 and the like, and the atmosphere during CO/~2
25 hydrocarbon synthesis conditions described below. Also,
26 the reduction and carbiding steps can be conducted con-
27 currently in CO/H2.
28 Also, a subject of the instant invention is
29 a ~ischer-Tropsch fixed bed process for producing C2-C6
30 olefins by utilizing the treated iron-manganese spinel,
31 described hereinabove
~3g~
1 Although a fixed bed Fischer-Tropsch process
2 is a preferred mode for operating the process,
3 utilizing the catalysts described herein, a slurry type
4 process wherein the catalyst is suspended in a liquid
5 hydrocarbon can also be utilized.
6 The subject fixed bed process utilizes the
7 above-described materials as catalyst, as iron-mang-
8 anese spinel, isostructural with Fe3O4, and its reducea
g and carbided forms. The reduced and carbided materials
10 are generally made in situ in the apparatus prior to,
11 and during the carrying out of the hydrocarbon syn-
12 thesis process. ~ full discussion of the spinel and
13 reduced form materials, their properties and thei~
14 preparation are given hereinabove and need not be re-
15 iterated.
16 Prior to the CO/hydrogen hydrocarbon
17 synthesis fixed bed run, the sintered iron-manganese
18 catalyst is generally conditioned in the apparatus by
19 purging with nitrogen to remove reactive oxygen con-
20 taining gases and then the temperature is increased to
21 the reaction temperature range. Then the system is
22 generally subjected to a hydrogen treatment for several
23 hours. The pressure and space velocity during this
24 conditioning step are not critical and can be utilized
25 in the range which is actually used during actual
26 hydrocarbon synthesis.
27 Following the reduction step, th~
28 CO/hydrogen feedstream is introduced into the apparatu~
29 catalyst chamber and the pressure, space velocityJ
30 temperature, and hydrogen/CO molar ratio are then
31 adjusted as desired, for hydrocarbon synthesis con-
32 ditions. Alternately, the reduction and carbiding
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1 steps can be carried out concurrently by contacting the
2 promoted spinel with CO/H2 atmosphere at elevated
3 temperature or under hydrocarbon synthesis conditions.
4 In the process, the hydrogen and CO are used
5 in a molar ratio in the gaseous feedstream of prefer-
6 ably about a 0.5 to 2.5 molar H2/CO ratio and prefe-
7 rably 1:1 to 2:1 molar ratio. Higher and lower molar
8 ratios may also be used.
9 The temperature in the process is generally
10 in the region of about 200 to 350C and preferably
11 being 250 to 300C.
12 The pressure useful in the process is gen-
13 erally conducted in the range of about 50 to 1000 psig
14 and preferably about 100 to 300 psig. Higher æressures
15 can also be used.
16 The space velocity (SHSV) used in the pro-
17 cess is generally about 200 to 4000 volume oE gaseous
18 feedstream/per volume of dry catalyst/per hour and is
19 preferably in the range of about 400 to 1200 V/V/hr.
2~ Higher and lower space velocities can also be used.
21 The percent CO conversion obtainable in the
22 subject process while providing substantial quantities
23 of C2-C6 olefins, ranges from about 20 to 98% and
24 preferably above about 30%. Higher and lower ratio
25 percentages of CO conversion may also be utilized.
26 "Total hydrocarbons" produced in the process
27 is related to the selectivity of percent ro conversion
28 to hydrocarbons, being those hydrocarbons from Cl to
~6~6
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1 about C~o inclusive, and is generally about 0 to 50
2 percent and higher of the total C0 converted, and the
3 remainder being converted to CO2.
4 The percent total C2-C6 hydrocar~ons of the
5 total hydrocarbons produced, including olefins and
6 paraffins is generally about 20 to 50 wt.% and pre-
7 ferably about 40 to 50 wt.%. The weight percent of
8 C2-C6 olefins produced of the C2-C6 total hydrocarbons
9 produced is generally about 50 to 90 wto% and prefer-
10 ably above 60 wt.% of the C2-C6 total hydrocarbons.
11 The olefins produced in the process are substantially
12 alpha-olefins.
13 The selectivity to methane based on the
14 amount of CO conversion is about 4 -to 10 weight percent
15 of total hydrocarbons produced. Preferably about 8
16 percent and lower methane is produced in the process.
17 ~s discussed above the percent selectivity
18 to CO2 formation in the process is about 40 to 50
19 percent of CO converted.
The reaction process variables are prefer-
21 ably adjusted to minimize CO2 production, minimize
22 methane production, maximize percent CO conversion, and
23 maximize percent C2-C6 olefin selectivity, while
24 achieving activity maintenance in the catalyst syste~.
Generally, this format can be achie~ed i~ a
26 preferred mode of operating the process where the
27 empirical formula of the catalyst used is
28 Fe2~2sMno~75o4/l%K the pretreatment procedure is
29 conducted at 500C, 9:1 H2/N2, 5 5 hrs. 100 psig,
30 500-750 v/v/hr, the CO/hydrogen molar ratio is 1~ he
31 temperature is conducted in the range 270-320C, a~ a
~36~
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1 pressure of 150-300 psig, and space velocity 800-1200
2 v/v/hr. By carrying out the above process in the
3 stated variable ranges eEficient activity maintenance
~ and production of C2-C6 olefins can be achieved.
The effluent gases in the process exiting
6 from the reactor may be recycled if desired to -the
7 reactor for further CO/hydrocarbon synthesis.
8 Methods for collecting the products in the
g process are known in the art and include distillation,
10 fractional distillation, and the like. Methods for
11 analyzing the product liquid hydrocarbons and gaseous
12 streams are also known in the art and generally include
13 gas chromatography, liquid chromatography, high
14 pressure liquid chromatography and the like.
Apparatus useful in the preferred process is
16 any conventional fixed bed type reactor, being hori-
17 zontal or vertical, moving bed, and the like. Other
18 apparatus not specifically described herein will be
19 obvious to one skilled in the art from a reading of
20 this disclosure
21 The following examples are illustration of
22 the best mode of carrying out the claimed invention as
23 contemplated by us and should not be construed as being
24 limiting on the scope and spirit of the i~stant
25 invention.
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1 EXAMPLE 1
2 Catalyst Preparation
3 Solid solutions of the composition
4 Fe3_yMnyO4 (where y varies from 0.025 to 2.85 and x as
5 originally defined equals 3-y) were prepared by
6 carefully weighing and thoroughly mixing Mn3O4, Fe2O3
7 and Fe powder (reagent quality or better -Alfa
8 Chemicals Co.) according to the stoichiometry:
9 -3 Mn34 + (-3 - 9 ) Fe23 + (-3 - -9) Fe >Fe3_yMnyO4
The individual spinels were prepared from
11 the following mixtures of starting materials accordin~
12 to the value of "y" as given below in the Table:
13 TABLE I
14 Catalyst y Fe2O3(9 ) Fe(g.~ Mn3o4(g~)
15 Control 0 21.080 1.84000.00
16 A 0.15 21.853 1.91081.2360
17 B 0.375 20.146 1.76153.0927
18 C 0.75 17.293 1.51196.1946
19 D 1.0 15.3886 1.33798.2668
E 1.5 23.124 2.022124.849
21 F 2.85 1.0646 0.093121.737
22 Each solids mixture was placed into a quartz tube
23 (15 mm i.d., 18mm o.d.) evacuated to 10-3 torr, sealed
24 under vacuum and then heated to 800C for 24 hours. The
25 resulting solids were isolated, thoroughly reground~
26 pelletized and resubjected to the same high temperature
~6~6
- 16 -
l sintering process at 800-1000C for an additional 24 to
2 48 hours. Powder X-ray diffraction analysis was the~
3 conducted to ensure that the material was single phase
4 and isostructural with Fe3O4. The catalyst pellets
5 were then impregnated with aqueous solutions of K2CO3
6 or K2SO~ to achieve a potassium loading level of l-lO
7 gm atom percent K per gm atom of combined metal, and
8 then dried, pelletized crushed and sieved to 10-4
9 mesh.
The resulting measured BET nitrogen surface
11 area of each Fe-Mn spinel was measured and the results
12 given below.
13 TABLE II
14 Spinel Empirical Formula Surface Area ~m2/g)
15 Control Fe3O4/1% K 0.27
16 A Ee2.85MnO.15O4/1% K 0.36
17 B Fe2.625Mn0.3754/l% K 0.28
18 C Fe2,25Mno.75o4/l% K 0.21
19 D Fe2MnO4/1~ K 0.25
E Fel,5Mnl.5O4/1% K 0.19
21 F Fe,lsMn2.8sO4/l% K 0.28
22 It is pointed out that Spinels E and F are
23 comparative examples.
24 EXAMPLE 2
About 8.8 cc. of the above-prepared spinel C
2~ (where x=0.75) was placed into an upflow 304 SS stainl-
27 less steel reactor (0.51 inch I.D.) and pretreated with
28 a gaseous stream of H2 and (helium, nitrogen) in a 1~3
29 volume ratio at lO0 psig at 500C and 600 v/v/hr.
~2:3~26
- 17 -
l (SHSV) for 5.5 hours. Then the pretreated catalyst was
2 contacted with a 1:1 H2:CO feedstream in helium at 300
3 psig, at 305C, and a space velocity of lO00 v/v/hr
4 (SHSC) for one or more hours and the products
5 collected and analyzed by gas chromotography versus
6 known standards. The results are listed below in Table
7 III. Unless otherwise indicated, the listed tempera-
8 tures in the process are furnace temperatures.
9 A Comparative run was made under substan-
lO tially the same conditions using a Fe3O4/1%K catalys-t
ll as prepared by the procedure described above in Example
12 l).
~3~
- 18 -
1 TABLE III
2 Catalyst Fe84/1% KFe2.25Mn.75o4/l~ K
3 Bed Temp tC) 350 305
4 H2/CO feed 1.0 1.0
5 SHSV (v/v/hr) 1000 1000
6 Pressure (psig) 300 300
7 % CO Conversion 87 92
8 to C2
9 to HC's 38 48
10 Wt.% Selectivity (CO2-free basis)
11 CH4 19.0 9.6
12 C2 5.7 8.6
13 c3= 15.9 14.9
14 c4= 8.6 10.2
15 Cs= 6.0
16 C2-C5 15.4 7.0
17 C6=-C20 14.9 20.1
18 C6-C20 10.4 15.7
19 C21+ 5.1 7.9
As is seen from the data, the Mn-containing
21 spinel catalyst provides greater activity, lower meth-
22 ane and higher C2-Cs alpha-olefin selectivity than the
23 all iron analg-
24 EXAMPLE 3
Catalyst D, as prepared by the proceduLe
26 outlined in Example 1, where y = 1.0, was promoted with
27 1 gm.-atom ~ K as K2CO3 or K2SO4. Samples of 8.8 cc of
28 the catalysts were pretreated with H2 at 100 psig, 600
;
- 19 -
1 v/v/hr and maintained at 500C for 5.5 hr. Then, CO
2 hydrogenation conditions were employed at: 300C, 1:1
3 H2/CO, SHSV of 1000 v/v/hr and 300 psig in the tubular
4 upflow 304 SS reactor described in Example 2. Results
5 are provided in Table IV.
6 TABLE IV
7 Performance of ~e2MnO4/1~ K
8 As a Function of Potassium Promoter
9 Promoter K2CO3 K2SO4
10 ~ CO ConversiOn94.4 96.3
11 to CO2 42.0 41.0
12 to HC's 52.4 55.3
13 Wt.% Selectivity
14 CH4 6.6
C2=-C6 18.5 35.9
16 C2-C6 4.8 5.6
17 c7+ 6g.0 51.9
_
18 Conditions: 300C, 1:1 H2:CO, 1000 v/v/hr., 300 psig
19 As seen in the above results, the use of
20 K2SO4 as a promoter leads to higher selectivity to
21 alpha-olefins. (See also W.L. Van Dijk et al., Applied
22 Catalysis, 2 (1982) pp. 273-288).
23 EXAMPLE 4
24 Catalysts prepared by the procedure outlined
25 in Example 1, where y = C.15, 0.75, 1.0 and 2.85, with
26 1~ wt. K as K2CO3 employed as a promoter were pretrea-
27 ted according to the procedure described in Example 2
28 and then subjected to CO hydrogenation conditions:
- 2n -
l 270C, 0.66:1 H2:CO, SHSV of lO00 v/v/hr and 300 psig
2 in the tubular 304 SS upflow reactor described in
3 Example 2 for 12 hours. Results are provided in Table
4 V.
TABLE V
6 Per~ormance of Fe3_yMnyO4/1% K
7 as a Function of Fe:Mn Ratio
8 Y= 0.15 0.75 1.0 2.85
9 Fe:Mn 19 3 2 0.05
lO % CO Conversion80.0 89.~ 38.9 <5.0
ll to CO2 32.0 35.0 18.9 NAa
12 to HC's 48.0 54.1 20.0 NA
13 Wt.% Select
14 CH4 6.5 4.3 5.0 NA
15 C2 -C6 22.8 19.2 32.2 NA
16 C2-C6~ 4.8 3~2 7.8 NA
17 C7+ 65.9 73.3 55.0 NA
18 Conditions: 270C, 0.66:1 H2:CO, 1000 v/v/hr, 300
19 psig.
aNot available
21 As seen in the above results, catalys-ts with
22 an Fe:Mn atomic ratio > 2.0 give good activity and
23 selectivity to alpha-olefin although catalysts with
24 Fe:Mn > 2.0 exhibit diminished activity relative to
25 more iron rich analogs.
