U.S. patent application number 13/579070 was filed with the patent office on 2012-12-27 for method for making a cobalt metal foam catalyst in which a cobalt catalyst powder is coated onto the surface of a metal foam, the cobalt metal foam catalyst, a thermal-medium- circulating heat-exchange reactor using the cobalt metal foam catalyst, and a method for producing a liquid fuel by means of .
This patent application is currently assigned to KOREA INSTITUTE OF ENERGY RESEARCH. Invention is credited to Dong-Hyun Chun, Heon Jung, Hak-Joo Kim, Chang-Hyun Ko, Ho-Tae Lee, Jung-Hoon Yang, Jung-Il Yang.
Application Number | 20120329889 13/579070 |
Document ID | / |
Family ID | 44483138 |
Filed Date | 2012-12-27 |
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United States Patent
Application |
20120329889 |
Kind Code |
A1 |
Yang; Jung-Il ; et
al. |
December 27, 2012 |
METHOD FOR MAKING A COBALT METAL FOAM CATALYST IN WHICH A COBALT
CATALYST POWDER IS COATED ONTO THE SURFACE OF A METAL FOAM, THE
COBALT METAL FOAM CATALYST, A THERMAL-MEDIUM- CIRCULATING
HEAT-EXCHANGE REACTOR USING THE COBALT METAL FOAM CATALYST, AND A
METHOD FOR PRODUCING A LIQUID FUEL BY MEANS OF A FISCHER-TROPSCH
SYNTHESIS REACTION USING THE THERMAL-MEDIUM-CIRCULATING
HEAT-EXCHANGE REACTOR
Abstract
The present invention relates to a method of manufacturing a
cobalt metal foam catalyst including a metal foam coated with
cobalt catalyst powder, a cobalt metal foam catalyst manufactured
by the method, a thermal medium-circulated heat exchanger type
reactor using the cobalt metal foam catalyst, and a method of
producing liquid fuel by Fischer-Tropsch synthesis using the
reactor. An object of the present invention is to provide a
catalyst, which is used to obtain high liquid fuel productivity
even at a low CO conversion ratio because the reaction temperature
can be kept stable by controlling reaction heat with high
efficiency in Fischer-Tropsch synthesis so that the mass transfer
characteristics of a catalyst layer can be improved, and a method
of manufacturing the catalyst, a reactor filled with the catalyst,
and a method of producing liquid fuel using the reactor. The method
of manufacturing a cobalt metal foam catalyst includes the steps
of: surface-pretreating a metal foam by atomic layer deposition
(ALD) using trimethylaluminum ((CH.sub.3).sub.3Al) and water to
form an Al.sub.2O.sub.3 thin film; preparing a cobalt catalyst
slurry composed of a mixture of alumina sol, cobalt catalyst powder
and isopropyl alcohol; surface-coating the surface-pretreated metal
foam with the cobalt catalyst slurry by dip coating; and drying and
calcinating the surface-pretreated metal foam coated with the
cobalt catalyst slurry.
Inventors: |
Yang; Jung-Il; (Daejeon,
KR) ; Yang; Jung-Hoon; (Daejeon, KR) ; Ko;
Chang-Hyun; (Daejeon, KR) ; Jung; Heon;
(Daejeon, KR) ; Lee; Ho-Tae; (Daejeon, KR)
; Kim; Hak-Joo; (Daejeon, KR) ; Chun;
Dong-Hyun; (Daejeon, KR) |
Assignee: |
KOREA INSTITUTE OF ENERGY
RESEARCH
Daejeon
KR
|
Family ID: |
44483138 |
Appl. No.: |
13/579070 |
Filed: |
February 25, 2010 |
PCT Filed: |
February 25, 2010 |
PCT NO: |
PCT/KR10/01187 |
371 Date: |
August 23, 2012 |
Current U.S.
Class: |
518/712 ;
422/199; 502/260; 502/331; 502/332 |
Current CPC
Class: |
B01J 37/0248 20130101;
B01J 37/0244 20130101; C10G 2/34 20130101; B01J 8/22 20130101; C10G
2300/70 20130101; B01J 2208/00212 20130101; B01J 35/04 20130101;
C10G 2/332 20130101; B01J 37/0225 20130101; B01J 23/75 20130101;
B01J 37/0217 20130101; B01J 37/16 20130101; B01J 37/0219 20130101;
B01J 37/0238 20130101; B01J 37/0205 20130101 |
Class at
Publication: |
518/712 ;
502/332; 502/331; 502/260; 422/199 |
International
Class: |
B01J 23/755 20060101
B01J023/755; B01J 19/00 20060101 B01J019/00; C07C 1/04 20060101
C07C001/04; B01J 23/75 20060101 B01J023/75 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 16, 2010 |
KR |
10-2010-0013851 |
Claims
1. A method of manufacturing a cobalt metal foam catalyst including
a metal foam coated with cobalt catalyst powder, comprising the
steps of: surface-pretreating a metal foam by atomic layer
deposition (ALD) using trimethylaluminum ((CH.sub.3).sub.3Al) and
water to form an Al.sub.2O.sub.3 thin film; preparing a cobalt
catalyst slurry composed of a mixture of alumina sol, a cobalt
catalyst and isopropyl alcohol; surface-coating the
surface-pretreated metal foam with the cobalt catalyst slurry by
dip coating; and drying and calcinating the surface-pretreated
metal foam coated with the cobalt catalyst slurry.
2. The method of manufacturing a cobalt metal foam catalyst
according to claim 1, wherein the metal foam is made of any one
selected from the group consisting of aluminum, iron, stainless
steel, iron-chromium-aluminum alloy (Fe--Cr--Al alloy),
nickel-chromium alloy, copper-nickel alloy, aluminum-copper alloy,
zinc-copper alloy and silver-copper alloy.
3. The method of manufacturing a cobalt metal foam catalyst
according to claim 1, wherein the cobalt catalyst slurry is
prepared by mixing a mixed solution including alumina sol and
isopropyl alcohol with cobalt catalyst powder such that a mixing
ratio of the mixed solution to the cobalt catalyst powder is
10:1.about.1:5.
4. The method of manufacturing a cobalt metal foam catalyst
according to claim 3, wherein the mixed solution including alumina
sol and isopropyl alcohol is prepared by mixing alumina sol
including alumina and water with isopropyl alcohol, and the mixed
solution has a viscosity of 1.about.50 cP.
5. The method of manufacturing a cobalt metal foam catalyst
according to claim 1, wherein the cobalt catalyst is prepared by
impregnating a support selected from the group consisting of
alumina (Al.sub.2O.sub.3), silica (SiO.sub.2) and titania
(TiO.sub.2) with a cobalt precursor selected from the group
consisting of cobalt nitrate (Co(NO.sub.3).sub.26H.sub.2O) and
cobalt acetate ((CH.sub.3CO.sub.2).sub.2Co4H.sub.2O).
6. The method of manufacturing a cobalt metal foam catalyst
according to claim 1, wherein the dip coating and drying are
repetitively performed several times such that the surface of the
metal foam is coated with the cobalt catalyst to form a thin film
which has strong adhesivity to the surface of the metal foam.
7. A cobalt metal foam catalyst including a metal foam coated with
cobalt catalyst powder, manufactured by the method of claim 1,
wherein, when a Fischer-Tropsch synthesis reaction is performed
using the metal foam catalyst, a reaction temperature is maintained
constant at an initial reaction temperature of
190.about.250.degree. C. in spite of high exothermic reaction heat,
and a high liquid fuel productivity of 98.2 mL.sub.liquid
fuel/(kg.sub.catalyst*hr) is obtained even at a low CO conversion
ratio of 46.8%.
8. A thermal medium-circulated heat exchanger type reactor,
comprising: a tube unit configured such that synthesis gas is
supplied to a cobalt catalyst layer filled with the cobalt metal
foam catalysts each including a metal foam coated with cobalt
catalyst powder, each of the metal foam and the cobalt catalyst
powder having been manufactured by the method of claim 1, to
conduct a reaction; a shell unit configured to cover the tube unit
such that thermal medium oil having a predetermined temperature is
circulated to control reaction heat generated from a
Fischer-Tropsch synthesis reaction; and an electric heater provided
at the circumference of the shell unit to heat a cobalt catalyst
layer to reduce and pretreat the cobalt catalyst layer.
9. The thermal medium-circulated heat exchanger type reactor
according to claim 8, further comprising: a heat exchange pin
protruding from an outer surface of the tube unit to accelerate
heat exchange between the tube unit and the thermal medium oil.
10. The thermal medium-circulated heat exchanger type reactor
according to claim 8, wherein the thermal medium oil is supplied by
a thermal medium oil storage tank supplying thermal medium oil to a
lower portion of the shell unit through a thermal medium oil supply
line and recovering high-temperature thermal medium oil discharged
from an upper portion of the shell unit through a thermal medium
oil recovery line and then storing the high-temperature thermal
medium oil; a thermal medium oil circulation pump provided along
the thermal medium oil supply line to supply the thermal medium oil
stored in the thermal medium oil storage tank; and a heat exchanger
provided along the thermal medium oil supply line located behind
the thermal medium oil circulation pump to perform heat exchange
between cooling water and thermal medium oil to control reaction
temperature.
11. The thermal medium-circulated heat exchanger type reactor
according to claim 8, wherein the electric heater for heating the
cobalt catalyst layer to reduce and pretreat the cobalt catalyst
layer is configured such that the cobalt catalyst layer is heated
to 300.about.500.degree. C.
12. The thermal medium-circulated heat exchanger type reactor
according to claim 10, wherein the circumference of the thermal
medium storage tank is with a heater to control the temperature of
the stored thermal medium oil.
13. A method of producing liquid fuel by a Fischer-Tropsch
synthesis reaction using a thermal medium-circulated heat exchanger
type reactor, wherein the thermal medium-circulated heat exchanger
type reactor of claim 10 using the cobalt metal foam catalyst
including a metal foam coated with cobalt catalyst powder is used,
and exothermic reaction heat generated by the Fischer-Tropsch
synthesis reaction occurring in the cobalt metal foam catalyst
layer of the tube unit is controlled by thermal medium oil
circulating in the shell unit at a reaction temperature of
190.about.250.degree. C. and a reaction pressure of 20.about.25
atm, and simultaneously the reaction is conducted, thus producing
liquid fuel.
14. The method of producing liquid fuel according to claim 13,
wherein the reaction is performed while increasing a heat exchange
efficiency using a heat exchange pin provided on an outer surface
of the tube unit during the Fischer-Tropsch synthesis reaction.
15. The method of producing liquid fuel according to claim 13,
wherein the exothermic reaction heat recovered by thermal medium
oil of the shell unit is removed by a heat exchanger that controls
the temperature of the thermal medium oil using external cooling
water to maintain the temperature of the thermal medium oil
constant.
16. The method of producing liquid fuel according to claim 15,
wherein the temperature of the thermal medium oil is adjusted to
190.about.250.degree. C.
17. The method of producing liquid fuel according to claim 13,
wherein the cobalt catalyst layer is reduced and pretreated by
heating it to 300.about.500.degree. C.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method of manufacturing a
cobalt metal foam catalyst including a metal foam coated with
cobalt catalyst powder, a cobalt metal foam catalyst manufactured
by the method, a thermal medium-circulated heat exchanger type
reactor using the cobalt metal foam catalyst, and a method of
producing liquid fuel by a Fischer-Tropsch synthesis reaction using
the reactor. More particularly, the present invention relates to a
catalyst, which is used to obtain high liquid fuel productivity
even at a low CO conversion ratio because the reaction temperature
can be kept stable by controlling the reaction heat with high
efficiency during the Fischer-Tropsch synthesis reaction, so that
the mass transfer characteristics in a catalyst layer can be
improved, and to a method of manufacturing the catalyst, a reactor
filled with the catalyst, and a method of producing liquid fuel
using the reactor.
BACKGROUND ART
[0002] Generally, when liquid fuel is produced from synthesis gas
by a Fischer-Tropsch synthesis reaction, technologies of producing
liquid fuel by filling a fixed-bed reactor or a slurry reactor with
a powdered catalyst and spherical or pelleted cobalt catalyst
particles is used.
[0003] As prior arts of the Fischer-Tropsch synthesis reaction
using a cobalt catalyst, U.S. Pat. No. 4,605,680 discloses a
technology of manufacturing a cobalt catalyst supported with
gamma-alumina or eta-alumina and activated with a group IIIB or IVB
metal oxide, and U.S. Pat. No. 4,717,702 discloses a technology of
manufacturing a cobalt catalyst having high dispersibility and a
small particle size using an impregnation solution including an
organic solvent. Further, U.S. Pat. No. 6,130,184 discloses an
example of developing a high-activity cobalt catalyst by
transforming a catalyst precursor and a carrier precursor, and U.S.
Pat. Nos. 6,537,945 and 6,740,621 disclose technologies related to
the development of a catalyst having improved thermal stability and
wear resistance, respectively.
[0004] Meanwhile, as prior arts related to the development of a
reactor for the Fischer-Tropsch synthesis reaction, in the case of
a slurry reactor, U.S. Pat. Nos. 5,422,375 and 5,599,849 disclose
technologies related to the development of an inner filter for
separating a catalyst, and U.S. Pat. Nos. 5,157,054 and 5,348,982
disclose technologies related to the mixing of a catalyst and
reactants. Further, in the case of a fixed-bed reactor, U.S. Pat.
No. 6,211,255 discloses a technology related to a fixed-bed reactor
filled with a monolith catalyst for improving the mass transfer
characteristics and heat transfer characteristics of reactants and
products in the reactor, and Korean Patent Nos. 2008-0060739 and
2009-0037089 disclose technologies related to a fixed-bed reactor
filled with a metal structure catalyst for improving the mass
transfer characteristics and heat transfer characteristics of
reactants and products in the reactor. Further, U.S. Pat. No.
7,984,180 discloses a technology for effectively controlling
reaction heat in a microchannel reactor using a cobalt
catalyst.
[0005] However, as described in the above prior arts, when
conventional powdered or particulate cobalt catalysts are used,
there are problems in that it is very difficult to control reaction
temperature because of the extremely high exothermic reaction that
occurs during the Fischer-Tropsch synthesis process, and in that it
is difficult to selectively obtain various products including
gaseous products, such as CH.sub.4, CO.sub.2 and the like, and
liquid products, such as gasoline, diesel, wax and the like,
because the temperature of the reaction cannot be easily
controlled.
[0006] Therefore, it is required to develop a catalyst which can be
used to control the reaction heat and selectively produce liquid
fuel and can be used to replace conventional catalysts.
[0007] Further, in the slurry reactor, it is required to develop a
high-efficiency filter for separating liquid products and fine
catalyst particles, and, even in the fixed-bed reactor whose mass
transfer characteristics and heat transfer characteristics are
somewhat improved thanks to the development of a metal structure
catalyst. It is also required to develop a high-efficiency
fixed-bed reactor for efficiently recovering reaction heat because
the reactor will be scaled up in the future.
DISCLOSURE
Technical Problem
[0008] Accordingly, the present invention has been devised to solve
the above-mentioned problems, and an object of the present
invention is to provide a method of manufacturing a cobalt metal
foam catalyst including a metal foam coated with cobalt catalyst
powder, wherein the cobalt metal foam catalyst is used to obtain
high liquid fuel productivity even at a low CO conversion ratio
because it can keep the reaction temperature stable by controlling
reaction heat with high efficiency during a Fischer-Tropsch
synthesis reaction and it can improve the mass transfer
characteristics in a catalyst layer.
[0009] Another object of the present invention is to provide a
thermal medium-circulated heat exchanger type reactor using the
cobalt metal foam catalyst, wherein the cobalt metal foam catalyst
is used to obtain high liquid fuel productivity even at a low CO
conversion ratio because it can keep the reaction temperature
stable by controlling the reaction heat with high efficiency during
the Fischer-Tropsch synthesis reaction and it can improve the mass
transfer characteristics in a catalyst layer.
[0010] Still another object of the present invention is to provide
a method of producing liquid fuel, wherein liquid fuel can be
produced in a high yield even at a low CO conversion ratio using
the thermal medium-circulated heat exchanger type reactor using the
cobalt metal foam catalyst which can keep the reaction temperature
stable by effectively recovering reaction heat and can improve the
mass transfer characteristics in a catalyst layer.
Technical Solution
[0011] In order to accomplish the above objects, an aspect of the
present invention provides a method of manufacturing a cobalt metal
foam catalyst including a metal foam coated with cobalt catalyst
powder, including the steps of: surface-pretreating a metal foam by
atomic layer deposition (ALD) using trimethylaluminum
((CH.sub.3).sub.3Al) and water to form an Al.sub.2O.sub.3 thin
film; preparing a cobalt catalyst slurry composed of a mixture of
alumina sol, a cobalt catalyst and isopropyl alcohol;
surface-coating the surface-pretreated metal foam with the cobalt
catalyst slurry by dip coating; and drying and calcinating the
surface-pretreated metal foam coated with the cobalt catalyst
slurry.
[0012] The metal foam may be made of any one selected from the
group consisting of aluminum, iron, stainless steel,
iron-chromium-aluminum alloy (Fe--Cr--Al alloy), nickel-chromium
alloy, copper-nickel alloy, aluminum-copper alloy, zinc-copper
alloy and silver-copper alloy.
[0013] The cobalt catalyst slurry may be prepared by mixing a mixed
solution including alumina sol and isopropyl alcohol with cobalt
catalyst powder such that a mixing ratio of the mixed solution to
the cobalt catalyst powder is 10:1.about.1:5.
[0014] The mixed solution including alumina sol and isopropyl
alcohol may be prepared by mixing alumina sol including alumina and
water with isopropyl alcohol, and the mixed solution has a
viscosity of 1.about.50 cP.
[0015] The cobalt catalyst may be prepared by impregnating a
support selected from the group consisting of alumina
(Al.sub.2O.sub.3), silica (SiO.sub.2) and titania (TiO.sub.2) with
a cobalt precursor selected from the group consisting of cobalt
nitrate (Co(NO.sub.3).sub.26H.sub.2O) and cobalt acetate
((CH.sub.3CO.sub.2).sub.2Co4H.sub.2O).
[0016] The dip coating and drying may be repetitively performed
several times such that the surface of the metal foam is coated
with the cobalt catalyst to form a thin film which has strong
adhesivity to the surface of the metal foam.
[0017] Another aspect of the present invention provides a cobalt
metal foam catalyst including a metal foam coated with cobalt
catalyst powder, manufactured by the method, wherein, when a
Fischer-Tropsch synthesis reaction is performed using the metal
foam catalyst, the reaction temperature is maintained constant at
an initial reaction temperature of 190.about.250.degree. C. in
spite of the high exothermic reaction heat, and a high liquid fuel
productivity of 98.2 mL.sub.liquid fuel/(kg.sub.catalyst*hr) is
obtained even at a low CO conversion ratio of 46.8%.
[0018] Still another aspect of the present invention provides a
thermal medium-circulated heat exchanger type reactor, including: a
tube unit configured such that synthesis gas is supplied to a
cobalt catalyst layer filled with the cobalt metal foam catalysts
each including a metal foam coated with cobalt catalyst powder,
each of the metal foam and the cobalt catalyst powder having been
manufactured by the method of any one of claims 1 to 6, to conduct
a reaction; a shell unit configured to cover the tube unit such
that thermal medium oil having a predetermined temperature is
circulated to control reaction heat generated from a
Fischer-Tropsch synthesis reaction; and an electric heater provided
at the circumference of the shell unit to heat a cobalt catalyst
layer to reduce and pretreat the cobalt catalyst layer.
[0019] The thermal medium-circulated heat exchanger type reactor
may further include: a heat exchange pin protruding from an outer
surface of the tube unit to accelerate heat exchange between the
tube unit and the thermal medium oil.
[0020] The thermal medium oil may be supplied by a thermal medium
oil storage tank supplying thermal medium oil to the lower portion
of the shell unit through a thermal medium oil supply line and
recovering high-temperature thermal medium oil discharged from the
upper portion of the shell unit through a thermal medium oil
recovery line and then storing the high-temperature thermal medium
oil; a thermal medium oil circulation pump provided along the
thermal medium oil supply line to supply the thermal medium oil
stored in the thermal medium oil storage tank; and a heat exchanger
provided along the thermal medium oil supply line located behind
the thermal medium oil circulation pump to perform heat exchange
between the cooling water and the thermal medium oil to control the
reaction temperature.
[0021] The electric heater for heating the cobalt catalyst layer to
reduce and pretreat the cobalt catalyst layer may be configured
such that the cobalt catalyst layer is heated to
300.about.500.degree. C.
[0022] The circumference of thermal medium storage tank may be
provided with a heater to control the temperature of the stored
thermal medium oil.
[0023] Still another aspect of the present invention provides a
method of producing liquid fuel by a Fischer-Tropsch synthesis
reaction using a thermal medium-circulated heat exchanger type
reactor, wherein the thermal medium-circulated heat exchanger type
reactor of claim 10 using the cobalt metal foam catalyst including
a metal foam coated with cobalt catalyst powder is used, and
exothermic reaction heat generated by the Fischer-Tropsch synthesis
reaction occurring in the cobalt metal foam catalyst layer of the
tube unit is controlled by thermal medium oil circulating in the
shell unit at a reaction temperature of 190.about.250.degree. C.
and a reaction pressure of 20.about.25 atm, and simultaneously the
reaction is conducted, thus producing liquid fuel.
[0024] The reaction may be performed while increasing the heat
exchange efficiency using a heat exchange pin provided on an outer
surface of the tube unit during the Fischer-Tropsch synthesis
reaction.
[0025] The exothermic reaction heat recovered by the thermal medium
oil of the shell unit may be removed by a heat exchanger that
controls the temperature of the thermal medium oil using external
cooling water to maintain the temperature of the thermal medium oil
constant.
[0026] The temperature of the thermal medium oil may be adjusted to
190.about.250.degree. C.
[0027] The cobalt catalyst layer may be reduced and pretreated by
heating it to 300.about.500.degree. C.
Advantageous Effects
[0028] According to the present invention, when a cobalt metal foam
catalyst including a metal foam coated with cobalt catalyst powder
is manufactured such that the problem of controlling the reaction
temperature by recovering the reaction heat, which is considered as
the greatest problem in the Fischer-Tropsch synthesis reaction for
making liquid fuel from carbon monoxide and hydrogen, can be
effectively solved, thanks to the metal properties of the metal
foam, high liquid fuel productivity can be obtained even at a low
CO conversion ratio because the cobalt metal foam catalyst can keep
the reaction temperature stable by controlling the reaction heat
with high efficiency even when carrying out the Fischer-Tropsch
synthesis and can improve the mass transfer characteristics of a
catalyst layer.
[0029] Further, according to the thermal medium-circulated heat
exchanger type reactor and the method of producing liquid fuel
using the reactor, the reaction heat removed by the cobalt metal
foam catalyst including the metal foam coated with cobalt catalyst
powder can be efficiently recovered, so that the reaction
temperature can be kept stable, thereby producing liquid fuel in a
high yield. Therefore, it is expected that the thermal
medium-circulated heat exchanger type reactor and the method of
producing liquid fuel using the reactor will find useful
application in industrial fields.
[0030] In particular, the method of producing liquid fuel according
to the present invention, which is a method of directly producing
liquid fuel from a small amount of natural gas on site at the
actual location, is a very effective energy utilization technology,
and is a very strong requirement of the diversification of various
energy sources and the security of being able to provide energy to
deal with ultrahigh oil prices.
DESCRIPTION OF DRAWINGS
[0031] FIG. 1 is a photograph showing a cobalt metal foam catalyst
in which a metal foam surface-pretreated by ALD is coated with
cobalt catalyst powder according to the present invention;
[0032] FIG. 2 is a flowchart showing a method of manufacturing the
cobalt metal foam catalyst according to the present invention;
[0033] FIG. 3 is a schematic view showing a thermal
medium-circulated heat exchanger type reactor according to the
present invention; and
[0034] FIG. 4 is a graph comparing the results of reaction
temperatures obtained from the Fischer-Tropsch synthesis reaction
using the thermal medium-circulated heat exchanger type reactor
filled with the cobalt metal foam catalyst with those obtained from
the Fischer-Tropsch synthesis reaction using the conventional
fixed-bed reactor filled with a spherical cobalt catalyst.
DESCRIPTION OF THE REFERENCE NUMERALS IN THE DRAWINGS
[0035] 1: metal foam [0036] 2: cobalt catalyst powder [0037] 3:
cobalt metal foam catalyst [0038] 201: tube unit [0039] 202: shell
unit [0040] 203: electric heater [0041] 204: cobalt metal foam
catalyst [0042] 205: heat exchange pin [0043] 206: thermal medium
oil storage tank [0044] 207: thermal medium oil storage tank heater
[0045] 208: thermal medium oil circulation pump [0046] 209: heat
exchanger [0047] 210: switching valve [0048] 211: hydrogen mass
flow controller (MFC) [0049] 212: carbon monoxide mass flow
controller [0050] 213: nitrogen mass flow controller [0051] 221:
synthesis gas supply line [0052] 222: nitrogen supply line [0053]
223: air injection unit [0054] 224: thermal medium oil recovery
unit [0055] 231: thermal medium oil [0056] 232: thermal medium oil
supply line [0057] 233: thermal medium oil recovery line [0058]
241: cooling water line [0059] 251: liquid fuel product recovery
unit
BEST MODE
[0060] Hereinafter, preferred embodiments of the present invention
will be described in detail with reference to the accompanying
drawings. Further, in the description of the present invention,
when it is determined that the detailed description of the related
art would obscure the gist of the present invention, the
description thereof will be omitted.
[0061] FIG. 1 is a photograph showing a cobalt metal foam catalyst
3 in which a metal foam 1 surface-pretreated by ALD is coated with
cobalt catalyst powder 2 according to the present invention, and
FIG. 2 is a flowchart showing a method of manufacturing the cobalt
metal foam catalyst 3 according to the present invention.
[0062] As shown in FIGS. 1 and 2, the cobalt metal foam catalyst in
which the metal foam surface-pretreated by ALD is coated with the
cobalt catalyst powder is manufactured by coating the surface of
the metal foam with a slurry composed of a mixture of alumina sol,
cobalt catalyst powder and isopropyl alcohol.
[0063] Conventionally, a fixed-bed reactor or a slurry reactor
using a powdered catalyst or a spherical or pelleted particulate
catalyst has been used as a reactor for carrying out a
Fischer-Tropsch synthesis reaction. In contrast, when the cobalt
metal foam catalyst manufactured by the method of the present
invention is used, the reaction heat generated during the
Fischer-Tropsch synthesis reaction can be efficiently removed to
control the reaction temperature stable because of the metal
properties of the metal foam, and liquid fuel, which is a reaction
product, is efficiently transferred to the outside of a catalyst
layer by the improved mass transfer characteristics because the
metal foam is coated with cobalt catalyst powder and so forms a
thin film, thereby achieving high liquid fuel productivity even at
a low CO conversion ratio.
[0064] The method of manufacturing the cobalt metal foam catalyst
according to the present invention includes the steps of:
surface-pretreating a metal foam by atomic layer deposition (ALD)
using trimethylaluminum ((CH.sub.3).sub.3Al) and water to form an
Al.sub.2O.sub.3 thin film; preparing a cobalt catalyst slurry
composed of a mixture of alumina sol, a cobalt catalyst and
isopropyl alcohol; surface-coating the surface-pretreated metal
foam with the cobalt catalyst slurry by dip coating; and drying and
calcinating the surface-pretreated metal foam coated with the
cobalt catalyst slurry.
[0065] As the cobalt catalyst, any catalyst may be used as long as
it is generally used in Fischer-Tropsch synthesis. Preferably, the
cobalt catalyst may be a catalyst prepared by impregnating a
support, such as alumina (Al.sub.2O.sub.3), silica (SiO.sub.2),
titania (TiO.sub.2) or the like, with a cobalt precursor, such as
cobalt nitrate (Co(NO.sub.3).sub.26H.sub.2O), cobalt acetate
((CH.sub.3CO.sub.2).sub.2Co4H.sub.2O) or the like.
[0066] The metal foam is made of aluminum, iron, stainless steel,
iron-chromium-aluminum alloy (Fe--Cr--Al alloy), nickel-chromium
alloy, copper-nickel alloy, aluminum-copper alloy, zinc-copper
alloy or silver-copper alloy. The metal foam is used to form a
stable Al.sub.2O.sub.3 thin film and coat cobalt catalyst powder
because it has heat transfer properties and high adhesivity to the
surface of the metal foam. Preferably, the metal foam may be made
of any one of iron-chromium-aluminum alloy (Fe--Cr--Al alloy),
nickel-chromium alloy, copper-nickel alloy, aluminum-copper alloy,
zinc-copper alloy and silver-copper alloy. Particularly,
copper-nickel alloy is most effective at forming the stable initial
interlayer that is necessary to form an Al.sub.2O.sub.3 thin film
on the surface of the metal foam in the process of
surface-pretreating the metal foam.
[0067] Atomic layer deposition (ALD) is a process of
surface-treating a metal foam to evenly coat the surface of the
metal foam with a cobalt catalyst. ALD is a process of forming a
compact Al.sub.2O.sub.3 thin film on the surface of the metal foam
using trimethylaluminum and water.
[0068] The reason for this is that it is difficult to form a stable
interface on the surface of the metal foam because the properties
of the metal foam are different from those of the catalyst which
includes inorganic matter as a main component. Therefore, in order
to solve this problem, an interlayer having properties similar to
those of a catalyst including inorganic matter as a main component
is formed on the surface of the metal foam.
[0069] Since the surface of the metal foam is completely covered
with an Al.sub.2O.sub.3 thin film by ALD, the surface property of
the metal foam is changed to that of Al.sub.2O.sub.3, which is
inorganic matter.
[0070] That is, the uniform Al.sub.2O.sub.3 thin film that
completely covers the surface of the metal foam is not formed by a
general coating method, and can be formed only by the ALD of the
present invention.
[0071] In the present invention, the cobalt catalyst slurry applied
onto the surface of the metal foam pretreated by ALD is prepared by
mixing alumina sol, cobalt catalyst powder and isopropyl
alcohol.
[0072] In the composition of the cobalt catalyst slurry, the mixing
ratio of a mixed solution of alumina sol and isopropyl alcohol to
cobalt catalyst powder may be 10:1.about.1:5.
[0073] Here, when the mixing ratio of the mixed solution of alumina
sol and isopropyl alcohol to cobalt catalyst powder is more than
the upper limit, the concentration of the cobalt catalyst slurry is
excessively low, so that the adhesivity of the cobalt catalyst
slurry is very low, with the result that it is difficult to form a
catalyst coating layer on the surface of the metal foam. Further,
when the mixing ratio thereof is less than the lower limit, the
concentration of the cobalt catalyst slurry is excessively high, so
that the thickness of the catalyst coating layer formed on the
surface of the metal foam increases, with the result that the
amount of catalyst particles which fail to be exposed to the
surface of the coating layer increases, thereby increasing the loss
of catalyst particles which are active in the Fischer-Tropsch
synthesis.
[0074] Further, the mixed solution including alumina sol and
isopropyl alcohol is prepared by mixing alumina sol including
alumina and water with isopropyl alcohol. The mixed solution is
configured such that its viscosity is 1.about.50 cP. The reason for
limiting the numerical value of the viscosity is because it is
difficult to suitably apply the cobalt catalyst slurry onto the
surface of the metal foam when the viscosity thereof is less than
the lower limit or more than the upper limit.
[0075] FIG. 3 is a schematic view showing a thermal
medium-circulated heat exchanger type reactor according to the
present invention.
[0076] As shown in FIG. 3, the thermal medium-circulated heat
exchanger type reactor according to the present invention is
configured such that the problem of pressure drop which occurs
during a Fischer-Tropsch synthesis reaction is effectively solved
and such that the reaction heat in the Fischer-Tropsch synthesis
reaction, which is a strong exothermic reaction, can be efficiently
controlled, so that the reaction temperature can be controlled and
kept stable and the mass transfer characteristics of a catalyst
layer can be improved, thereby producing liquid fuel in a high
yield even when the CO conversion ratio is low. Without providing
this thermal medium-circulated heat exchanger type reactor, when
the Fischer-Tropsch synthesis reaction is carried out, the loss of
active catalyst particles charged in a reactor is large, which is
inefficient, and the reaction temperature is not easily
controlled.
[0077] In order to solve such a problem, the thermal
medium-circulated heat exchanger type reactor according to the
present invention includes: a tube unit 201 configured such that
synthesis gas is supplied to a cobalt catalyst layer 204 filled
with a plurality of cobalt metal foam catalysts each including a
metal foam coated with cobalt catalyst powder to carry out a
reaction; a shell unit 202 configured to cover the tube unit 201
such that thermal medium oil having a predetermined temperature is
circulated to control the reaction heat generated from the
Fischer-Tropsch synthesis reaction; a heat exchange pin 205
protruding from the outer surface of the tube unit 201 to
accelerate the heat exchange between the tube unit 201 and the
thermal medium oil; an electric heater 203 provided at the
circumference of the shell unit 202 to heat a cobalt catalyst layer
to reduce and pretreat the cobalt catalyst layer; a thermal medium
oil storage tank 206 supplying the thermal medium oil 231 to the
lower portion of the shell unit 202 through a thermal medium oil
supply line 232 and recovering high-temperature thermal medium oil
discharged from the upper portion of the shell unit 201 through a
thermal medium oil recovery line 233 and then storing the
high-temperature thermal medium oil; a thermal medium oil
circulation pump 208 provided along the thermal medium oil supply
line 232 to supply the thermal medium oil stored in the thermal
medium oil storage tank 206; and a heat exchanger 209 provided
along the thermal medium oil supply line 232 located behind the
thermal medium oil circulation pump 208 to perform heat exchange
between cooling water and thermal medium oil to control reaction
temperature.
[0078] The thermal medium storage tank 206 is provided at the
circumference thereof with a heater 207 to control the temperature
of the stored thermal medium oil.
[0079] Further, the thermal medium oil supply line 232 is provided
with a thermal medium oil recovery unit 224 to control the amount
of the thermal medium oil discharged from the thermal medium
storage tank 206.
[0080] Further, the thermal medium oil recovery line 233 is
provided with an air injection unit 223 for injecting air when the
circulated thermal medium oil is recovered by the thermal medium
oil recovery unit 224 provided in the thermal medium oil supply
line 232 and provided with a switching valve 210 that controls the
injection of air.
[0081] The top of the tube unit 201 is connected to a mixed gas
supply line 221 for supplying a mixed gas of hydrogen passing
through a hydrogen mass flow controller 211 and carbon monoxide
passing through a carbon monoxide mass flow controller 212. Also,
the mixed gas supply line 221 is connected to a nitrogen supply
line 222 for supplying nitrogen passing through a nitrogen mass
flow controller 213. Further, the bottom of the tube unit 201 is
connected to a liquid fuel product recovery unit 251 for recovering
liquid fuel produced while passing through the cobalt catalyst
layer 204 provided in the tube unit 201.
[0082] The electric heater 203 for heating the cobalt catalyst
layer to reduce and pretreat the cobalt catalyst layer 204 is
configured such that the cobalt catalyst layer 204 is heated to
300.about.500.degree. C. When the cobalt catalyst layer is heated
to below the lower limit, it is difficult to activate a cobalt
catalyst, although the activation of the cobalt catalyst is
necessary for carrying out the Fischer-Tropsch synthesis reaction
for producing liquid fuel. Further, when the cobalt catalyst layer
is heated to above the upper limit, it is difficult to maintain the
stability of the cobalt catalyst at high temperature.
[0083] The temperature of the thermal medium oil is maintained at
190.about.250.degree. C. When the temperature thereof is below the
lower limit, it is difficult to run the Fischer-Tropsch synthesis
reaction. Further, when the temperature thereof is above the upper
limit, during the Fischer-Tropsch synthesis reaction, undesirable
side reactions, such as the formation of an excess amount of
gaseous products (CH.sub.4, CO.sub.2, etc.), catalyst coking
ascribed to carbon deposition causing catalytic deactivation and
the like, frequently occur, compared to the production of liquid
fuel.
[0084] The above-configured thermal medium-circulated heat
exchanger type reactor using the cobalt metal foam catalyst
including a metal foam coated with cobalt catalyst powder according
to the present invention can effectively and rapidly control the
exothermic reaction heat that is generated by the Fischer-Tropsch
synthesis reaction occurring in the cobalt metal foam catalyst
layer of the tube unit by using the thermal medium oil circulating
in the shell unit at a predetermined temperature. Further, the heat
exchange pin provided on the outer surface of the tube unit can
increase the heat exchange efficiency. Also, the exothermic
reaction heat that is recovered by the thermal medium oil of the
shell unit is removed by the exchanger controlling the temperature
using external cooling water, so that the temperature of the
thermal medium oil of the shell unit is maintained constant.
[0085] As the result of performing the Fischer-Tropsch synthesis
reaction using the cobalt metal foam catalyst of the present
invention and the thermal medium-circulated heat exchanger type
reactor of the present invention under the conditions of a reaction
temperature of 190.about.250.degree. C. and a reaction pressure of
20.about.25 atm, first, the problem of pressure drop in the
reaction operation was effectively solved. Further, the reaction
heat generated by the Fischer-Tropsch synthesis reaction, which is
an extremely exothermic reaction, was efficiently controlled, so
that the reaction temperature was kept stable and the mass transfer
characteristics in the catalyst layer was improved, thereby
obtaining high liquid fuel productivity even at a low CO conversion
ratio.
[0086] The reason for limiting the numerical value ranges of the
reaction temperature and reaction pressure is because the highest
production yield was obtained in these numerical value ranges.
[0087] FIG. 4 is a graph comparing the results of reaction
temperatures obtained from the Fischer-Tropsch synthesis reaction
using the thermal medium-circulated heat exchanger type reactor
filled with the cobalt metal foam catalyst with those obtained from
the Fischer-Tropsch synthesis reaction using the conventional
fixed-bed reactor filled with a spherical cobalt catalyst.
[0088] As shown in FIG. 4, when the Fischer-Tropsch synthesis
reaction was performed using the thermal medium-circulated heat
exchanger type reactor filled with the cobalt metal foam catalyst,
very stable reaction temperature control results (results according
to Example 5) were obtained. In contrast, when the Fischer-Tropsch
synthesis reaction was performed using the conventional fixed-bed
reactor filled with a spherical cobalt catalyst, irregular reaction
temperature control results (results according to Comparative
Example 1) were obtained.
[0089] As shown in FIG. 4, when the initial reaction temperature of
the Fischer-Tropsch synthesis reaction using the thermal
medium-circulated heat exchanger type reactor filled with the
cobalt metal foam catalyst was set 190.about.250.degree. C., the
reaction temperature was maintained constant at the initial
reaction temperature even when the Fischer-Tropsch synthesis
reaction, which is an extremely exothermic reaction, was ran for a
long period of time because the reaction temperature was controlled
stable by controlling the reaction heat with high efficiency.
Further, in this case, the mass transfer characteristics of the
cobalt metal foam catalyst were improved, so that high liquid fuel
productivity was obtained even at a low CO conversion ratio
(results according to Example 5)
[0090] As described above, from the Fischer-Tropsch synthesis
reaction using the thermal medium-circulated heat exchanger type
reactor filled with the cobalt metal foam catalyst according to the
present invention, it can be ascertained that the reaction
temperature can be controlled stable by controlling the reaction
heat with high efficiency, and the mass transfer characteristics of
the cobalt metal foam catalyst can be improved, so that high liquid
fuel productivity can be obtained even at a low CO conversion
ratio.
MODE FOR INVENTION
[0091] Hereinafter, the present invention will be described in more
detail with reference to the following Examples and Comparative
Example. However, the scope of the present invention is not limited
to these Examples.
[0092] The CO conversion ratio, liquid fuel yield, liquid fuel
productivity and hydrocarbon yield in Example 5 and Comparative
Example 1 are defined as follows.
CO conversion=reacted CO moles/supplied CO moles*100=(supplied CO
moles-unreacted CO moles)/supplied CO moles*100
Liquid fuel yield=produced liquid fuel (gasoline, diesel, wax)
moles/supplied CO moles*100
Liquid fuel productivity=liquid fuel produced per hour (gasoline,
diesel, wax)/used catalyst
Hydrocarbon yield=produced hydrocarbon (ethane, propane, butane,
gasoline, diesel, wax) moles/supplied CO moles*100
Example 1
[0093] To pretreat metal foam to be used in catalyst surface
coating, in order to form an Al.sub.2O.sub.3 thin film, a metal
foam (diameter: 22 mm, thickness: 4 mm) made of an copper-nickel
alloy was surface-treated by atomic layer deposition (ALD) using
trimethylaluminum (CH.sub.3).sub.3Al) and water. In the first step,
trimethylaluminum (TMA) was supplied. The supplied TMA reacts with
a hydroxyl group (--OH) present on the surface of the metal to form
a metal-O--Al bond. In the second step, residual TMA and CH.sub.4
(reaction side products) are washed with an inert gas such as
nitrogen, argon or the like. In the third step, water is supplied.
The unreacted methyl group present on the surface of the metal
reacts with the supplied water to form an Al--OH bond. In the
fourth step, water (unreacted reactant) and CH.sub.4 are removed
using inert gas in the same manner as in the second step. While
carrying out these four steps, a monolayer film is formed, and this
is defined as one cycle. In the following step, the supplied TMA
reacts with Al--OH to form an Al--O--Al bond. Therefore, the
surface of the metal is chemically bonded, not physically adhered
to, with an Al.sub.2O.sub.3 thin film to form a surface thin film,
and the thickness of the surface thin film can be adjusted in a
range of 1.about.100 nm by adjusting the number of cycles in the
ALD process.
Example 2
[0094] In order to prepare a catalyst slurry to be applied onto the
surface-treated metal foam, 50 g of alumina sol, 15 g of cobalt
catalyst powder and 20 mL of isopropyl alcohol were mixed to
prepare a cobalt catalyst slurry.
Example 3
[0095] The surface-treated metal foam was coated with the prepared
cobalt catalyst slurry by dip coating, dried at 120.degree. C., and
then calcinated at 400.degree. C. to manufacture a cobalt metal
foam catalyst.
Example 4
[0096] A thermal medium-circulated heat exchanger type reactor
including a tube unit filled with a cobalt metal foam catalyst and
a shell unit in which a thermal medium circulates was made of a
double tube including an inner tube having a diameter of 1 inch and
an outer tube having a diameter of 2 inches. The length of the
reactor was 430 mm. The inner tube of the tube unit having a
diameter of 1 inch was filled with eighty cobalt metal foam
catalysts, and the outer surface of the tube unit was provided with
a heat exchange pin for the purpose of efficient heat exchange. In
the outer tube having a diameter of 2 inches of the shell unit,
thermal medium oil, the temperature of which is controlled constant
at 222.degree. C. by an additional exchanger using external cooling
water, was circulated by an oil pump, and the thermal medium oil
having passed through the shell unit of the heat exchanger type
reactor was recovered into a thermal medium oil storage tank and
then recirculated by the oil pump. Three thermocouples was provided
in the center of the tube unit filled with cobalt metal foam
catalysts at 200 mm intervals depending on the height of a cobalt
metal foam catalyst layer to measure the reaction temperature. In
order to reduce and pre-treat the cobalt metal foam catalyst layer,
the heat exchanger type reactor was heated to 300.degree. C. using
an electric heater provided on the outer circumference of the shell
unit.
Example 5
[0097] The Fischer-Tropsch synthesis reaction was ran by supplying
H.sub.2 at a flow rate of 200 mL/min and CO at a flow rate of 100
mL/min as reactants using the eighty cobalt metal foam catalysts
and the thermal medium-circulated heat exchanger type reactor under
the conditions of a reaction temperature of 222.degree. C. and a
reaction pressure of 20 atm. In the Fischer-Tropsch synthesis
reaction using the cobalt metal foam catalysts and the thermal
medium-circulated heat exchanger type reactor, during the reaction,
the reaction temperature was maintained constant at the initial
reaction temperature regardless of the high exothermic reaction
heat. As a result, the CO conversion was 46.8%, liquid fuel yield
was 31.4%, liquid fuel productivity was 98.2 mL.sub.liquid
fuel/(kg.sub.catalyst*hr), and hydrocarbon yield was 37.5%.
Comparative Example 1
[0098] In order to compare the reaction activity obtained from the
Fischer-Tropsch synthesis reaction using the cobalt metal foam
catalyst of Example 5 and the thermal medium-circulated heat
exchanger type reactor with that obtained from running a
Fischer-Tropsch synthesis reaction using a general spherical cobalt
catalyst and a general fixed-bed reactor, the Fischer-Tropsch
synthesis reaction was performed by filling the fixed-bed reactor
with 4.5 g of the spherical cobalt catalyst and supplying H.sub.2
at a flow rate of 67 mL/min and CO at a flow rate of 33 mL/min as
reactants under the conditions of a reaction temperature of
220.degree. C. and a reaction pressure of 20 atm.
[0099] Immediately after initiation of the reaction, there was a
sudden rise in the reaction temperature, which increased to
280.degree. C. in 40 minutes, so that the catalyst was deactivated
by the precipitation of carbon, with the result that the
Fischer-Tropsch synthesis reaction did not proceed, and thus liquid
fuel was not produced.
[0100] Although the preferred embodiments of the present invention
have been disclosed for illustrative purposes, those skilled in the
art will appreciate that various modifications, additions and
substitutions are possible, without departing from the scope and
spirit of the invention as disclosed in the accompanying
claims.
* * * * *