U.S. patent application number 11/302106 was filed with the patent office on 2006-09-28 for method and structure for desulfurizing gasoline or diesel fuel for use in a fuel cell power plant.
Invention is credited to Zissis A. Dardas, He Huang, Roger R. Lesieur.
Application Number | 20060213813 11/302106 |
Document ID | / |
Family ID | 34116200 |
Filed Date | 2006-09-28 |
United States Patent
Application |
20060213813 |
Kind Code |
A1 |
Huang; He ; et al. |
September 28, 2006 |
Method and structure for desulfurizing gasoline or diesel fuel for
use in a fuel cell power plant
Abstract
A sulfur scrubbing method and structure is operable to remove
substantially all of the sulfur present in an undiluted oxygenated
hydrocarbon fuel stock supply which can be used to power an
internal combustion engine or a fuel cell power plant in a mobile
environment, such as an automobile, bus, truck, boat, or the like,
or in a stationary environment. The fuel stock can be gasoline,
diesel fuel, or other like fuels which contain relatively high
levels of organic sulfur compounds such as mercaptans, sulfides,
disulfides, thiophenes, and the like. The undiluted hydrocarbon
fuel supply is passed through a desulfurizer bed which is provided
with a high surface area nickel reactant, and wherein essentially
all of the nickel reactant in the scrubber bed reacts with sulfur
in the fuel stream, so as to remove sulfur from the fuel stream by
converting it to nickel sulfide on the scrubber bed. The
desulfurized organic remnants of the fuel stream continue through
the remainder of the fuel processing system in the fuel cell power
plant, or through the internal combustion engine. The desulfurizer
bed is preferably formed from a high surface area ceramic foam
monolith, the pores of which are coated with the high surface area
nickel reactant. The use of the foam monolith combined with the
high surface area of the reactant, enables essentially 100% of the
nickel reactant to come into contact with the fuel stream being
desulfurized. The scrubber bed can also be formed from high surface
area nickel coated alumina pellets, from a high surface area nickel
coated ceramic extrusion, from high surface area nickel pellets,
and from high surface area nickel extrudates.
Inventors: |
Huang; He; (Glastonbury,
CT) ; Dardas; Zissis A.; (Worcester, MA) ;
Lesieur; Roger R.; (Enfield, CT) |
Correspondence
Address: |
William W. Jones;Patent Counsel
6 Juniper Lane
Madison
CT
06443
US
|
Family ID: |
34116200 |
Appl. No.: |
11/302106 |
Filed: |
December 13, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10635268 |
Aug 7, 2003 |
|
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11302106 |
Dec 13, 2005 |
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Current U.S.
Class: |
208/208R |
Current CPC
Class: |
B01J 2219/2453 20130101;
B01J 20/02 20130101; B01J 20/3042 20130101; B01J 2219/00081
20130101; B01J 2219/2459 20130101; B01J 20/28057 20130101; B01J
2219/2485 20130101; B01J 20/103 20130101; B01J 20/28059 20130101;
H01M 8/0675 20130101; B01J 19/249 20130101; B01J 2208/00132
20130101; B01J 20/3293 20130101; B01J 35/04 20130101; B01J
2219/00085 20130101; Y02E 60/50 20130101; B01J 37/0215 20130101;
B01J 23/755 20130101; B01J 2220/42 20130101; B01J 20/28016
20130101; B01J 20/3289 20130101; B01J 2208/0015 20130101; B01J
20/28042 20130101; B01J 19/2485 20130101; B01J 20/08 20130101; B01J
20/28097 20130101; B01J 20/3236 20130101; C10G 29/04 20130101; B01J
20/28014 20130101; B01J 2219/2479 20130101; B01J 19/2495 20130101;
B01J 20/28045 20130101; B01J 2219/2458 20130101; B01J 20/06
20130101; C10G 25/003 20130101; B01J 20/3204 20130101 |
Class at
Publication: |
208/208.00R |
International
Class: |
C10G 45/00 20060101
C10G045/00; C10G 17/00 20060101 C10G017/00 |
Claims
1. (canceled)
2. (canceled)
3. (canceled)
4. (canceled)
5. (canceled)
6. (canceled)
7. (canceled)
8. (canceled)
9. (canceled)
10. (canceled)
11. A method for producing a sulfur scrubbing assembly that is
operative to remove sulfur from a gasoline or diesel fuel stream,
said method comprising the steps of: a) providing a support
structure for the assembly; b) providing said support structure
with a coating that includes nickel oxide and that has a surface
area of greater than about fifty square meters per gram of said
coating; and c) reducing said nickel oxide in said coating to
nickel.
12. The method of claim 11 wherein said support structure is
porous.
13. The method of claim 12 wherein said porous support structure is
a foam.
14. The method of claim 12 wherein said porous support structure is
an extruded ceramic monolith.
15. The method of claim 11 wherein said coating is a
co-precipitated mixture of nickel and one or more high surface area
non-reducible oxide.
16. (canceled)
Description
TECHNICAL FIELD
[0001] The present invention relates to a method and structure for
desulfurizing gasoline, diesel fuel or like hydrocarbon fuel
streams so as to render the fuel more suitable for use in a mobil
vehicular fuel cell power plant assembly or in an internal
combustion engine. More particularly, the desulfurizing method and
structure of this invention are operable to reduce the amount of
organic sulfur compounds found in these fuels to levels which will
not poison the catalysts in the fuel processing section of the fuel
cell power plant assembly and will not harm components of an
internal combustion engine. The method and structure of this
invention comprise a highly porous nickel coated reactant bed which
has an extended useful life cycle due to the inclusion of the
porous nickel coat. The nickel in the coat is reduced from nickel
oxide to nickel after being applied to the scrubber bed support.
The reduced nickel removes sulfur from the fuel stream by
converting the sulfur to nickel sulfide that deposits on the
reactant coated surfaces of the scrubber bed.
BACKGROUND OF THE INVENTION
[0002] Gasoline, diesel fuel, and like hydrocarbon fuels have
generally not been used as a process fuel source suitable for
conversion to a hydrogen rich stream for small mobile fuel cell
power plants due to the existence of relatively high levels of
naturally-occurring complex organic sulfur compounds. The presence
of sulfur results in a poisoning effect on all of the catalysts
used in the hydrogen generation system in a fuel cell power plant.
Conventional fuel processing systems used with stationary fuel cell
power plants include a thermal steam reformer, such as that
described in U.S. Pat. No. 5,516,344. In such a fuel processing
system, sulfur is removed by conventional hydrodesulfurization
techniques which typically rely on a certain level of recycle as a
source of hydrogen for the process. The recycle hydrogen combines
with the organic sulfur compounds to form hydrogen sulfide within a
catalytic bed. The hydrogen sulfide is then removed using a zinc
oxide bed to form zinc sulfide. The general hydrodesulfurization
process is disclosed in detail in U.S. Pat. No. 5,292,428. While
this system is effective for use in large stationary applications,
it does not readily lend itself to mobile transportation
applications because of system size, cost and complexity.
Additionally, the fuel gas stream being treated must use large
quantities of process recycle in order to provide hydrogen in the
gas stream, as noted above.
[0003] Other fuel processing systems, such as conventional
autothermal reformers, which use a higher operating temperature
than conventional thermal steam reformers, can produce a
hydrogen-rich gas in the presence of the aforesaid complex organic
sulfur compounds without prior desulfurization. When using an
autothermal reformer to process raw fuels which contain complex
organic sulfur compounds, the result is a loss of autothermal
reformer catalyst effectiveness and the requirement of reformer
temperatures that are 200.degree. F.-500.degree. F. (93.degree.
C.-260.degree. C.) higher than are required with a fuel having less
than 0.05 ppm sulfur. Additionally, a decrease in useful catalyst
life of the remainder of the fuel processing system occurs with the
higher sulfur content fuels. The organic sulfur compounds are
converted to hydrogen sulfide as part of the reforming process. The
hydrogen sulfide can then be removed using a solid absorbent
scrubber, such as an iron or zinc oxide bed to form iron or zinc
sulfide. The aforesaid solid scrubber systems are limited, due to
thermodynamic considerations, as to their ability to lower sulfur
concentrations to non-catalyst degrading levels in the fuel
processing components which are located downstream of the reformer,
such as in the shift converter, or the like.
[0004] Alternatively, the hydrogen sulfide can be removed from the
gas stream by passing the gas stream through a liquid scrubber,
such as sodium hydroxide, potassium hydroxide, or amines. Liquid
scrubbers are large and heavy, and are therefore useful principally
only in stationary fuel cell power plants. From the aforesaid, it
is apparent that current methods for dealing with the presence of
complex organic sulfur compounds in a raw fuel stream for use in a
fuel cell power plant require increasing fuel processing system
complexity, volume and weight, and are therefore not suitable for
use in mobile transportation systems.
[0005] An article published in connection with the 21 st Annual
Power Sources Conference proceedings of May 16-18, 1967, pages
21-26, entitled "Sulfur Removal for Hydrocarbon-Air Systems", and
authored by H. J. Setzer et al, relates to the use of fuel cell
power plants for a wide variety of military applications. The
article describes the use of high nickel content hydrogenation
nickel reactant to remove sulfur from a military fuel called JP-4,
which is a jet engine fuel, and is similar to kerosene, so as to
render the fuel useful as a hydrogen source for a fuel cell power
plant. The systems described in the article operate at relatively
high temperatures in the range of 600.degree. F. (320.degree. C.)
to 700.degree. F. (380.degree. C.). The article also indicates that
the system tested was unable to desulfurize the raw fuel alone,
without the addition of large quantities of water or hydrogen, due
to reactor carbon plugging. The carbon plugging occurred because
the tendency for carbon formation greatly increases in the
temperature range between about 550.degree. F. (290.degree. C.) and
about 750.degree. F. (460.degree. C.). A system operating in the
600.degree. F. to 700.degree. F. range would be very susceptible to
carbon plugging, as was found to be the case in the system
described in the article. The addition of either hydrogen or steam
reduces the carbon formation tendency by supporting the formation
of gaseous carbon compounds thereby limiting carbon deposits which
cause the plugging problem.
[0006] It would be highly desirable from an environmental
standpoint to be able to power electrically driven vehicles, such
as an automobile, for example, by means of fuel cell-generated
electricity; and to be able to use a fuel such as gasoline, diesel
fuel, naphtha, lighter hydrocarbon fuels such as butane, propane,
natural gas, or like fuel stocks, as the fuel consumed by the
vehicular fuel cell power plant in the production of electricity.
In order to provide such a vehicular power source, the amount of
sulfur in the processed fuel gas would have to be reduced to and
maintained at less than about 0.05 parts per million.
[0007] The desulfurized processed fuel stream can be used to power
a fuel cell power plant in a mobile environment. The fuel being
processed can be gasoline or diesel fuel, or some other fuel which
contains relatively high levels of organic sulfur compounds such as
thiophenes, mercaptans, sulfides, disulfides, and the like. The
fuel stream is passed through a nickel desulfurizer bed wherein
essentially all of the sulfur in the organic sulfur compounds
reacts with the nickel reactant and is converted to nickel sulfide
leaving a desulfurized hydrocarbon fuel stream which continues
through the remainder of the fuel processing system. U.S. Pat. No.
6,129,835, granted Oct. 10, 2000; and U.S. Pat. No. 6,156,084,
granted Dec. 5, 2000 describe systems for use in desulfurizing a
gasoline or diesel fuel stream for use in an internal combustion
engine; and a mobile fuel cell vehicular power plant, respectively.
The desulfurization beds in the aforesaid systems, both fixed and
mobile, would typically utilize alumina pellets which have been
admixed with the nickel reactant prior to being formed. Thus the
alumina powder and nickel powder are mixed together and the pellets
are then formed from the mixture. Using this procedure, a major
portion of the nickel reactant ends up in the interior of the
pellets, and is unable to contact the fuel stream being
desulfurized, and thus is wasted. The use of pelletized
desulfurization beds using a nickel reactant is thus inefficient to
a certain extent.
[0008] U.S. Pat. No. 6,140,266, granted Oct. 31, 2000 describes a
compact and light weight catalyst bed which is designed for use
with a fuel cell power plant which catalyst bed is useful in a fuel
cell power plant reformer assembly. The content of this patent is
incorporated into this application in its entirety. The foam
support provides a very high surface area bed with excellent flow
through characteristics. The use of such an open cell foam support
would provide a fuel desulfurizing bed that would ensure that
essentially 100% of the nickel reactant would be exposed to the
fuel stream being desulfurized. Thus, the use of an open cell foam
support member in a nickel-based reactant desulfurizing bed would
greatly increase the efficiency of the desulfurizer and also
increase its useful life.
[0009] We have discovered a way to further increase the useful life
of a sulfur scrubber bed and sulfur scrubbing method, by further
increasing the surface area of the reactant, irrespective of the
reactant support structures utilized in the scrubber bed. Our
improvement involves the use of a highly porous nickel oxide
reactant coating which is applied to all exposed surfaces in the
scrubber bed and thereafter reduced to nickel. The use of the
highly porous nickel reactant coating increases the useful life of
sulfur scrubber beds using alumina or silica pellets as the
reactant support, or using an open cell porous foam as the reactant
support, or using a honeycomb-type monolith structure as the
reactant support.
DISCLOSURE OF THE INVENTION
[0010] This invention relates to an improved desulfurizing bed
structure and method for processing a gasoline, diesel, or other
hydrocarbon fuel stream over an extended period of time, so as to
remove substantially all of the sulfur present in the fuel stream,
which structure and method provide a longer sulfur removal useful
life. The bed structure and method of this invention include a
support member onto which a highly porous nickel oxide material is
deposited. The nickel oxide coating is highly porous, i.e., it has
randomly distributed micro pores on its surface and has a very high
surface area. After the nickel oxide is reduced to nickel, the
micro pores will vary in size from one micron to fifty microns in
diameter. With the support micro porosity, the reduced nickel
reactant coat will result in a nickel surface area of over fifty
square meters per gram (M.sup.2/gm) of reactant in the scrubber bed
structure. This micro porosity and increase surface area greatly
increase the amount of nickel in the scrubber bed which is
available and able to react with sulfur in the fuel stream so as to
remove the sulfur from the fuel stream and convert it to nickel
sulfide on the scrubber bed surface. When all of the available
nickel sites on the scrubber bed surface have been converted to
nickel sulfide, then the scrubber bed will be deemed to have
reached a "sulfur breakthrough" condition and will be unable to
convert further sulfur in the fuel stream to produce the desired
low sulfur content fuel. By using the highly porous nickel coating
in lieu of a standard nickel coating, the useful life of the
scrubber bed is extended by a factor of about five.
[0011] Gasoline is a hydrocarbon mixture of paraffins, naphthenes,
olefins and aromatics, whose olefinic content is between 1% and
15%, and aromatics between 20% and 40%, with total sulfur in the
range of about 20 ppm to about 1,000 ppm. The national average for
gasoline in the United States is 350 ppm sulfur. The legally
mandated average for the State of California for gasoline is 30 ppm
sulfur. As noted above, the sulfur content of gasoline must be less
than about 0.05 ppm to be useful in a fuel cell power plant as a
source of hydrogen. This low level is also beneficial in that it
minimizes internal combustion engine damage from sulfur.
[0012] The effectiveness of a nickel adsorbent reactant to adsorb
organic sulfur compounds from gasoline depends on the relative
coverage of the active reactant sites by adsorption of all the
various constituents of gasoline. In other words, the
desulfurization process depends on the amount of competitive
adsorption of the various constituents of gasoline. From the
adsorption theory, it is known that the relative amount of
adsorbate on an adsorbent surface depends primarily on the
adsorption strength produced by attractive forces between the
adsorbate and adsorbent molecules and secondarily on the
concentration of the adsorbate in the gasoline, and temperature.
Coverage of a reactant surface by an adsorbate increases with
increasing attractive forces; higher fuel concentration; and lower
temperatures. Relative to gasoline, Somorjai (Introduction to
Surface Chemistry and Catalysis, pp, 60-74) provides some relevant
information on the adsorption of hydrocarbons on transition metal
surfaces, such as nickel. Saturated hydrocarbons only physically
adsorb onto the nickel reactant surface at temperatures which are
less than 100.degree. F. (40.degree. C.), therefore paraffins, and
most likely naphthenes, won't compete with sulfur compounds for
adsorption sites on the nickel reactant at temperatures above
250.degree. F. (121.degree. C.) and 300.degree. F. (149.degree.
C.).
[0013] On the other hand, unsaturated hydrocarbons, such as
aromatics and olefins, adsorb largely irreversibly on transition
metal surfaces even at room temperature. When an unsaturated
hydrocarbon such as an aromatic or an olefin adsorbs on a
transition metal surface, and the surface is heated, the adsorbed
molecule rather than desorbing intact, decomposes to evolve
hydrogen, leaving the surface covered by the partially
dehydrogenated fragment, i.e., tar or coke precursors. At
350.degree. F. (177.degree. C.), unsaturated hydrocarbons are
nearly completely dehydrogenated, and the dehydrogenated tar
fragments form multiple carbon atom-to-nickel reactant surface
bonds. This explains why aromatics and olefins in gasoline, in the
absence of oxygenated compounds in appropriate concentrations, will
deactivate the nickel reactant from adsorbing sulfur after a
relatively short period of time. To prevent this from occurring, it
is preferred to use gasoline which contains an oxygenate, such as
ethanol, methanol, MTBE, or the like, in order to generate a small
amount of hydrogen to prevent dehydrogenation of aromatics and
olefins in the gasoline.
[0014] Further nonessential but enabling information relating to
this invention will become readily apparent to one skilled in the
art from the following detailed description of a preferred
embodiment of the invention when taken in conjunction with the
accompanying drawings in which:
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] These and other objects and advantages of this invention
will become readily apparent to one skilled in the art from the
following detailed description of a preferred embodiment of the
invention when taken in conjunction with the accompanying drawings
in which:
[0016] FIG. 1 is a perspective view of one form of an open cell
foam monolith sulfur scrubber bed formed in accordance with this
invention;
[0017] FIG. 2 is a fragmented perspective view of a heat transfer
component and foam sulfur scrubber bed assembly which are bonded
together;
[0018] FIG. 3 is a perspective view of a sheet metal monolith
sulfur scrubber bed formed in accordance with this invention;
[0019] FIG. 4 is an end elevational view of the scrubber bed of
FIG. 3;
[0020] FIG. 5 is a fragmented perspective view of an extruded
ceramic monolith sulfur scrubber bed formed in accordance with this
invention; and
[0021] FIG. 6 is a graph comparing the performance of sulfur
scrubber beds formed in accordance with this invention with
conventional sulfur scrubber beds formed in accordance with the
prior art.
SPECIFIC MODE FOR CARRYING OUT THE INVENTION
[0022] Referring now to the drawings, there is shown in FIG. 1 a
perspective view of a rectilinear form of a sulfur scrubber bed
formed in accordance with this invention, which bed is denoted
generally by the numeral 2. The scrubber bed 2 is a monolithic open
cell foam support component which includes a lattice network of
tendrils 4 that form a network of open cells 6 which are
interconnected in the X, Y and Z directions within the bed 2. The
interconnected open cells 6 are operable to form an enhanced fuel
gas mixing and distribution flow path from end 8 to end 10 of the
bed 2. The open cells 6 and the tendrils 4 also provide a very
large nickel reactant-available surface area for coating in the bed
2. The core or support member of the foam scrubber bed 2 can be
formed from aluminum, stainless steel, an aluminum-steel alloy,
silicon carbide, nickel alloys, carbon, graphite, a ceramic, or the
like material. One preferred material is cordierite, which is a
porous ceramic alumina/silica mineral.
[0023] Typically, the bed 2 is coated with the highly porous nickel
oxide surface layer in the following manner. A coat of the highly
porous nickel oxide and an acid, such as acetic acid, nitric acid,
or the like, is applied to all outer and interstitial surfaces in
the foam core 2. The washcoat can be applied to the core 2 by
dipping the core 2 into a washcoat solution, or by spraying the
washcoat solution onto the core 2. The washcoated core 2 is then
calcined so as to form the solidified highly porous nickel oxide
layer on all surfaces of the core 2. The highly porous nickel oxide
wash coat is preferably one produced by Sud-Chemie, Inc. by
co-precipitating a highly dispersed nickel with non-reducible
oxides, such as alumina, silica, rare earth oxides, or the like.
The inclusion of the non-reducible oxides provides the enhanced
surface area for the nickel reactant, and prevents sintering of the
nickel surface, which would reduce the surface area thereof. The
co-precipitation of nickel and the oxides forms the washcoat, and
then the washcoat is applied to the support.
[0024] FIG. 2 is a fragmented perspective view showing separate
members of the nickel reactant coated foam components 2 which are
bonded to heat transfer components 48. By bonding the open cell
foam components 2 to an adjacent heat transfer components 48, which
can be planar walls, or coolant conduits, continuation of the high
thermal conductivity of the foam 2 into the heat transfer component
48 is achieved. The heat transfer components 48 can made of
aluminum, stainless steel, steel-based alloys containing aluminum,
or high nickel alloys, as dictated by requirements of the system
into which the components 2, 48 are incorporated.
[0025] Referring now to FIG. 3, there is shown a monolithic form of
a sulfur scrubber bed which is denoted generally by the numeral 12.
The scrubber bed 12 is formed from sheet metal components that can
be coated with the highly porous reducible nickel oxide layer
described herein. The bed 12 can be formed from a series of planar
components 14 which are spaced apart and are separated by honey
comb components 16 which are also formed from a washcoatable sheet
metal. The components 16 and the planar components 14 combine to
form through passages 18 which have their surfaces coated as
indicated by the numeral 20 in FIG. 4. The fuel stream being
desulfurized flows through the passages 18 in the direction
indicated by the arrows A.
[0026] Referring now to FIG. 5, there is shown yet another
embodiment of a sulfur scrubber module which is formed in
accordance with this invention. The desulfurizer module shown is
formed from an extruded ceramic monolith which is denoted generally
by the numeral 22. The monolith is preferably formed from
cordierite, which is an alumina-silica mineral which can be
artificially manufactured. The monolith 22 includes a plurality of
crisscrossing webs 24 which form through passages 26 that extend
through the monolith 22. All of the exposed surfaces on the
monolith 22 are coated with the reducible porous nickel oxide
material. The fuel being desulfurized passes through the monolith
22 in the direction of the arrows B. The sulfur scrubber can be
formed for a single monolith 22 or by a bundled plurality of the
monoliths 22.
[0027] In addition to the above-identified monolith reactant
support members, we have also discovered that the porous reducible
nickel oxide material described herein will increase the useful
life of a sulfur scrubber station which uses packed pellets as the
reactant support. The pellets will typically be formed from alumina
powder which is compressed into pellet form. The surface of the
formed pellets is then coated with the reducible nickel oxide
material which is then reduced to form the highly porous nickel
reactant. This method of coating the support pellets greatly
enhances the surface area of the reactant on the pellets and does
not result in unusable reactant, which can result when the pellets
are formed from a mixture of alumina powder and nickel powder,
wherein some of the nickel will be encapsulated inside of the
pellets and thus be rendered unusable in the desulfurizing
reaction.
[0028] Referring now to FIG. 6, there is shown a graph which
illustrates the improved performance of nickel based sulfur
scrubber beds that are formed in accordance with this invention as
compared with nickel based sulfur scrubber beds formed in
accordance with the prior art. The prior art scrubber beds used in
the comparison shown in FIG. 6 were formed from alumina pellets
that incorporated nickel powder as the sulfur adsorbent.
[0029] The Y axis of the graph indicates the concentration of
sulfur in the fuel stream being processed as measured by a sulfur
sensor incorporated into the scrubber bed. The X axis of the graph
shows the hours of service for the scrubber bed.
[0030] The scrubber beds formed in accordance with this invention
were made from alumina pellets that were coated with two different
but related coats of the enhanced surface area nickel oxide that
were both reduced to a nickel reactant. The graph illustrates a
sulfur breakthrough level of 0.05 ppm sulfur, shown as line 28.
This breakthrough level is the concentration of sulfur in the fuel
stream which is the uppermost sulfur concentration that a fuel cell
fuel processing assembly can tolerate. When the sulfur scrubber bed
becomes incapable of producing a fuel gas stream having less than
0.05 ppm sulfur in it, the scrubber bed will be considered to be
inoperable or spent.
[0031] As noted above, the scrubber beds that were formed in
accordance with the prior art used a lower surface area, i.e., less
than fifty M.sup.2/gm surface area, nickel sulfur adsorbent
incorporated into alumina pellets. The plots of sulfur
concentration v. time for the prior art sulfur scrubber beds are
indicated by the lines 30 and 32. It will be noted that sulfur
breakthrough occurred at approximately five hundred hours of bed
operation; and at approximately seven hundred hours as indicated by
the plots 30 and 32 of the two prior art sulfur scrubber beds
tested.
[0032] The performance plots of the two versions of sulfur scrubber
beds that were formed in accordance with this invention are denoted
by the lines 34 and 36. It will be noted that sulfur breakthrough
occurred at approximately twenty four hundred hours and
approximately three thousand hours as indicated by the plots 34 and
36 of the two sulfur scrubber beds tested that were formed in
accordance with this invention.
[0033] It will be noted that the sulfur scrubber beds formed in
accordance with the invention that are depicted in FIG. 6 were
formed with pelletized support members for the nickel reactant, and
still produced marked improvement in performance as compared to the
prior art which also utilized pelletized support members for the
nickel reactant.
[0034] When sulfur scrubber bed supports are formed from the foams
and extruded monoliths described above, and are used to support the
high surface area nickel reactant, the improvements in hours of
service will be even greater than shown in FIG. 6, because the
surface area of the foam and monolith supports which is washcoated
with the reduced nickel reactant is volumetrically much greater
than the surface area of a volume of packed alumina pellets which
are washcoated with the nickel reactant.
[0035] Monolith open cell foam cores of the type described above
can be obtained from ERG Energy Research and Generation, Inc. of
Oakland, Calif. which cores are sold under the registered trademark
"DUOCEL". Another source of the foam cores is Porvair, Inc., of
Ashville, N.C.
[0036] A high surface area reducible nickel oxide coat material of
the type described herein above can be obtained from Sud-Chemie,
Inc. of Louisville, Ky. The nickel oxide material available from
Sud-Chemie is identified by Sud-Chemie's product designations
T-2496 and T-2694A. The nickel oxide coat material is the most
preferred form of the nickel reactant due to longer term stability.
Alternatively, the nickel oxide material could be extruded to form
a high surface area support per se without requiring a separate
nickel oxide coating. Thus, the nickel oxide material could be used
as a coating on a support material, or it can be used as a reactant
without a separate support material. The nickel oxide is reduced to
nickel prior to use.
[0037] Since many changes and variations of the disclosed
embodiments of the invention may be made without departing from the
inventive concept, it is not intended to limit the invention other
than as required by the appended claims.
* * * * *