WO2018049212A1

WO2018049212A1 - Molten carbonate fuel cell stack having direct and indirect internal reformers

Info

Publication number: WO2018049212A1
Application number: PCT/US2017/050755
Authority: WO
Inventors: Ramakrishnan Venkataraman; Jin-Yun Wang; Mohammad Farooque; Lawrence Novacco
Original assignee: Fuelcell Energy, Inc.
Priority date: 2016-09-09
Filing date: 2017-09-08
Publication date: 2018-03-15

Abstract

A reforming catalyst includes a thermally stable core and an electrolyte removing component and/or an electrolyte repelling component, such that the thermally stable core comprises a metal oxide support and nickel disposed in the metal oxide support.

Description

Molten Carbonate Fuel Cell Stack Having Direct and Indirect Internal

Reformers

CROSS-REFERENCE TO RELATED PATENT APPLICATION

[0001] This application claims the benefit of U.S. Provisional Patent Application No.

62/385,477, filed on September 9, 2016, the entire disclosure of which is incorporated by reference herein.

BACKGROUND

[0002] The present disclosure relates to fuel cell stacks, and more particularly, to molten carbonate fuel cell stacks having both direct and indirect internal reformers.

[0003] A fuel cell is a device, which directly converts chemical energy stored in hydrocarbon fuel into electrical energy by means of an electrochemical reaction. Generally, a fuel cell comprises an anode and a cathode separated by an electrolyte, which serves to conduct electrically charged ions. Fuel cells operate by passing a reactant fuel gas through the anode, while passing oxidizing gas through the cathode. In order to produce a useful power level, a number of individual fuel cells are stacked in series with an electrically conductive separator plate between each cell.

[0004] Before undergoing the electrochemical reaction in the fuel cell, hydrocarbon fuels such as methane, coal gas, etc. are typically reformed to produce hydrogen for use in the anode of the fuel cell. In internally reforming fuel cells, a steam reforming catalyst is placed within the fuel cell stack to allow direct use of hydrocarbon fuels without the need for expensive and complex reforming equipment. In addition, the endothermic reforming reaction can be used

advantageously to help cool the fuel cell stack.

[0005] Internally reforming fuel cells employing direct internal reforming and indirect internal reforming have been developed. Direct internal reforming ("DIR") is accomplished by placing a reforming catalyst ("DIR catalyst") within the active anode compartment. This catalyst is exposed to the electrolyte of the fuel cell. [0006] The second reforming technique, indirect internal reforming ("IIR"), is accomplished by placing the reforming catalyst ("IIR catalyst") in an isolated chamber within the fuel cell stack and routing the reformed gas from this chamber into the anode compartment of the fuel cell.

[0007] The present state of the art utilizes a hybrid assembly of a fuel cell with both direct and indirect internal reforming. U.S. Patent No. 6,200,696 describes such a hybrid assembly, in which the indirect internal reformer is designed with a substantially U-shaped flow geometry, which allows the inlet fuel feed tubes to also be contained within the fuel-turn manifold thereby mitigating the risk of system fuel leaks. U.S. Patent Nos. 6,974,644 and 7,431,746 describe improvements on this assembly. These three patents, which are assigned to the same assignee as the present application, are incorporated by reference in their entireties.

SUMMARY OF THE INVENTION

[0008] The stability of the DIR catalyst has a significant impact on fuel cell stack life.

[0009] Embodiments of the present invention offer approaches to enhance the life of internally reforming fuel cells by using two pronged approach. First, a DIR catalyst that has lower activity but higher stability is used. Second, the catalyst arrangement in the IIR and DIR is optimized to provide enhanced heat removal in the fuel inlet region of the fuel cell while also raising the overall hydrocarbon conversion in the IIR and the anode outlet.

[0010] In certain embodiments, a reforming catalyst includes a thermally stable core and an electrolyte removing component and/or an electrolyte repelling component, wherein the thermally stable core comprises a metal oxide support and nickel disposed in the metal oxide support.

[0011] In one aspect, the metal oxide support includes at least one base metal oxide or ceramic material, and at least one transition metal oxide or rare earth metal oxide dispersed in the base metal oxide or ceramic material.

[0012] In one aspect, the metal oxide support has a surface area in a range of 5 m²/g to 120 m²/g. [0013] In one aspect, the nickel has a weight concentration in a range of 10 wt.% to 50 wt.% of the reforming catalyst.

[0014] In one aspect, the metal oxide support is a pre-sintered metal oxide support comprising at least one transition metal oxide or rare earth metal oxide.

[0015] In one aspect, the thermally stable core has a mean pore diameter in a range of 65A to 500A and a pore size distribution standard deviation of less than 50%.

[0016] In one aspect, the reforming catalyst comprises the electrolyte removing component and the electrolyte removing component is an electrolyte removing layer coating the thermally stable core to form a core-shell structure.

[0017] In one aspect, the reforming catalyst comprises the electrolyte removing component and the electrolyte removing component is dispersed in the thermally stable core.

[0018] In one aspect, the reforming catalyst comprises the electrolyte removing component and the electrolyte removing component comprises at least one of aluminum oxide, titanium oxide, zirconium oxide, tungsten oxide, or a mixture thereof.

[0019] In one aspect, the reforming catalyst comprises the electrolyte repelling component and the electrolyte repelling component is an electrolyte repelling layer coating the thermally stable core to form a core-shell structure.

[0020] In one aspect, the reforming catalyst comprises the electrolyte repelling component and the electrolyte repelling component is dispersed in the thermally stable core.

[0021] In one aspect, the reforming catalyst comprises the electrolyte repelling component and the electrolyte repelling component comprises at least one of graphite, a metal carbide, a metal nitride, or a mixture thereof.

[0022] In one aspect, the reforming catalyst comprises both the electrolyte removing component and the electrolyte repelling component. [0023] In one aspect, the electrolyte removing component is an electrolyte removing layer coating the thermally stable core and wherein the electrolyte repelling component is an electrolyte repelling layer coating the electrolyte removing layer.

[0024] In one aspect, the electrolyte removing component comprises at least one of aluminum oxide, titanium oxide, zirconium oxide, tungsten oxide, or a mixture thereof; and the electrolyte repelling component comprises at least one of graphite, a metal carbide, a metal nitride, or a mixture thereof.

[0025] In one aspect, a molten carbonate fuel cell having direct internal reforming, the molten carbonate fuel cell comprising an anode compartment and the reforming catalyst according to any embodiment or aspect disclosed herein, disposed in the anode compartment.

[0026] The foregoing is a summary of the disclosure and thus by necessity contains simplifications, generalizations, and omissions of detail. Consequently, those skilled in the art will appreciate that the summary is illustrative only and is not intended to be in any way limiting. Other aspects, features, and advantages of the devices and/or processes described herein, as defined by the claims, will become apparent in the detailed description set forth herein and taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG. 1 is a perspective view of a fuel cell stack having both direct and indirect internal reforming, according to an embodiment of the invention.

[0028] FIG. 2 is a graph showing relative catalyst activity over time for both a baseline DIR catalyst and a thermally aged DIR catalyst according to an embodiment of the invention.

[0029] FIG. 3 is a cutaway illustration of an example embodiment of a catalyst having a thermally stabilized support, according to an embodiment of the invention.

[0030] FIG. 4 is a graph showing relative catalyst activity over time for both a baseline DIR catalyst and a DIR catalyst having a thermally stabilized support according to an embodiment of the invention. [0031] FIG. 5 is a schematic diagram showing a gas flow over catalyst bed regions in an indirect internal reformer according to an embodiment of the invention.

[0032] FIG. 6A is a CFD simulation showing the change in temperature in the cell plane of a fuel cell when using a baseline DIR catalyst over the life of the fuel cell, assuming 100% activity at beginning of life (BOL) and 20% activity at end of life (EOL), and FIG. 6B is a CFD simulation showing the change in temperature in the cell plane of a fuel cell over the life of the fuel cell when using a low activity, high stability DIR catalyst according to an embodiment of the present invention, assuming 50% activity at BOL and 15% activity at EOL.

[0033] FIG. 7 is a schematic diagram showing a staggered DIR catalyst configuration according to an embodiment of the present invention.

[0034] FIG. 8 is a schematic diagram showing a gas flow in a DIR having perforated baffles according to an embodiment of the invention.

DETAILED DESCRIPTION

[0035] An example of an internally reforming fuel cell is shown in FIG. 1. Fuel (in this example, natural gas) flows into the IIR where it is partially reformed and follows a U-shaped path and exits the IIR on the same side of the fuel cell stack at which it entered the IIR. That partially reformed fuel then enters the fuel cells of the fuel cell stack on the same side of the fuel cell stack at which the fuel enters the IIR, where it is further reformed by the DIR catalyst. Oxidant gas flows through the fuel cells in a direction transverse to the flow of fuel.

[0036] In known internally reforming fuel cells, reforming catalysts used in the DIR are typically highly active high nickel surface area catalysts. High surface area catalysts undergo aging during fuel cell operation, which results in significant loss of the activity between the beginning of life (BOL) and end of life (EOL) of the catalyst. Known catalysts suffer from greater than a factor of five decrease in activity over the useful life of the catalysts.

[0037] Increasing the stability of the DIR catalyst will yield smaller changes in temperature distribution in the stack as a function of time, thereby ensuring longer stack life. Using a reduced activity DIR catalyst also decouples the reforming conversion in the DIR from thermal changes in the anode inlet region, because the temperature rise that occurs at the anode inlet with aging will not lead to greater amounts of hydrogen generation in the DIR, and therefore will not lead to an increase in the drawing of current, which results in heat generation in the anode inlet region.

[0038] A typical DIR catalyst loses 85% of activity over its life. The low activity high stability DIR catalyst of the present invention preferably loses 60% or less of its activity over its life; activity loss of less than 40% is preferable.

[0039] A surface area of the Ni in the catalyst is preferably in a range of 2-8 m²/g, and more preferably in a range of 2-6 m²/g.

[0040] Embodiments of the low activity high stability catalyst will next be described. Thermally Aged Catalysts

[0041] In one embodiment of the invention, the DIR catalyst is a thermally aged catalyst. Common reforming catalyst, typically Ni supported on alumina or silica or zirconia, can be thermally aged to improve stability. That is, the DIR catalyst is a catalyst that has been subject to heating at high temperature to reduce the activity of the catalyst. For example, the DIR catalyst may be thermally aged at a temperature of 700 °C or greater for 2 hours or longer prior to providing the catalyst in a fuel cell for use. Alternatively, sintering time and temperature can be adjusted based on the required nickel surface area for the catalyst that is being aged.

[0042] FIG. 2 is a graph showing relative catalyst activity over time during accelerated catalyst stability tests for both a baseline DIR catalyst and a partially thermally aged DIR catalyst according to an embodiment of the invention. Commercially available Ni catalyst supported on alumina was used as a baseline and also for thermal aging. This catalyst was heated to 700°C in an oven in air at the rate of 2°C/min and held at 700°C for 2 hours before cooling down to room temperature at the same rate as heat up. This catalyst showed decrease in Ni surface area compared to fresh non-heat treated catalyst. However, the Ni surface area was still well above the desired range of 2-8 m²/g. As can be seen in FIG. 2, the thermally aged DIR catalyst experiences less reduction in activity relative to the baseline DIR catalyst. This thermally aged catalyst is an illustrative example of thermal aging. It can be understood that, with longer thermal aging or aging at a higher temperature, Ni surface area can be reduced to a value within the desired range leading to substantially smaller reduction in activity. Catalysts Having Thermally Stabilized Supports

[0043] In another embodiment, the DIR catalyst is a catalyst having small amounts of well- dispersed nickel on thermally stabilized supports (referred to herein as a "supported catalyst"), as described in U.S. Provisional Application No. 62/321,043, filed April 11, 2016, which is assigned to the same assignee as the present application, and is hereby incorporated by reference in its entirety.

[0044] According to exemplary embodiments, a supported catalyst (10) includes a thermally stable core (12), as shown in FIG. 3, where the thermally stable core (12) includes a metal oxide support and nickel disposed in the metal oxide support. The metal oxide support includes at least one base metal oxide or ceramic material, and at least one transition metal oxide or rare earth metal oxide is mixed with or dispersed in the base metal oxide or ceramic material.

[0045] In some embodiments, the metal oxide support has a low to medium surface area to improve durability of the catalyst. In some embodiments, the metal oxide support has a surface area of about 5-120 m²/g, or about 5-20 m²/g, or about 20-50 m²/g, or about 50-120 m²/g.

[0046] In some embodiments, the metal oxide support comprises a mixture of at least two different metal oxides. In some embodiments, the metal oxide support comprises a mixture of at least three different metal oxides.

[0047] In some embodiments, the base metal oxide comprises alkaline earth metal oxide(s). In some embodiments, the base metal oxide comprises transition metal oxide(s). In some embodiments, the base metal oxide comprises post transition metal oxide(s). In some embodiments, the base metal oxide comprises rare earth metal oxide(s). In some embodiments, the base metal oxide comprises at least one of alumina and MgO.

[0048] The presence of the transition metal oxide(s) and/or rare earth metal oxide(s), in addition to the base catalyst, can stabilize the metal oxide support and also promote catalyst support interactions. In some embodiments, the thermally stable core comprises at least one transition metal oxide (e.g., ZrO_x, TiO_x) in addition to the base catalyst. In some embodiments, the thermally stable core comprises at least one rare earth metal oxide (e.g., LaO_x) in addition to the base catalyst. [0049] In some embodiments, the metal oxide support comprises at least two different transition metal oxides and/or rare earth metal oxides. In some embodiments, the metal oxide support comprises at least three different transition metal oxides and/or rare earth metal oxides.

[0050] In some embodiments, the transition metal oxide(s) and rare earth metal oxide(s) account for about 1-20 wt.%, or about 1-5 wt.% , or about 5-10 wt.%, or about 10-20 wt.% of the supported catalyst. In some embodiments, the transition metal oxide(s) and rare earth metal oxide(s) account for about 1-20 wt.%, or about 1-5 wt.% , or about 5-10 wt.%, or about 10-20 wt.%) of the thermally stable core.

[0051] In some embodiments, the supported catalyst has a medium to high Ni loading to provide adequate reforming rate under fuel cell operational conditions. In some embodiments, the nickel accounts for about 10-50 wt.%>, or about 10-20 wt.%> , or about 20-30 wt.%>, or about 30-50 wt.%) of the supported catalyst. In some embodiments, the nickel accounts for about 10- 50 wt.%, or about 10-20 wt.% , or about 20-30 wt.%, or about 30-50 wt.% of the thermally stable core.

[0052] In some embodiments, the nickel is deposited in the metal oxide support through co- precipitation of the nickel and the metal oxide. In some embodiments, the nickel is deposited in a stable (pre-sintered) metal oxide support which may also include transition metal oxide(s) and/or rare earth metal oxide(s).

[0053] In some embodiments, the supported catalyst or the thermally stable core has a low mean pore diameter and a narrow pore size distribution.

[0054] In some embodiments, the supported catalyst has a mean pore diameter of about 65- 500 A, or about 65-200 A, or about 200-300 A, or about 300-400 A, or about 400-500 A, as measured by mercury porosimetry of pelletized catalyst. In some embodiments, the thermally stable core has a mean pore diameter of about 65-500 A, or about 65-200 A, or about 200-300 A, or about 300-400 A, or about 400-500 A, as measured by mercury porosimetry of pelletized catalyst.

[0055] In some embodiments, the supported catalyst has a pore size distribution characterized by a standard deviation of less than about 50%>, or less than about 20%>, or less than about 10%> of the mean pore diameter. In some embodiments, the thermally stable core has a pore size distribution characterized by a standard deviation of less than about 50%, or less than about 20%), or less than about 10%> of the mean pore diameter.

[0056] In some embodiments, the supported catalyst is substantially or totally free of silicate. In some embodiments, the thermally stable core is substantially or totally free of silicate.

[0057] According to various exemplary embodiments, a supported catalyst (10) further comprises an electrolyte removing component (14) and/or an electrolyte repelling component (16), as shown in FIG. 3.

[0058] In some embodiments, the supported catalyst further comprises an electrolyte removing component to remove electrolyte that is in contact with the catalyst, wherein the electrolyte removing component comprises at least one metal oxide.

[0059] In some embodiments, the electrolyte removing component is in the form of an electrolyte removing layer coating the thermally stable core to form a core-shell structure. In some embodiments, the electrolyte removing component is mixed with or dispersed in the thermally stable core.

[0060] In some embodiments, the electrolyte removing component has a surface area of at least about 50 m²/g, or at least about 70 m²/g, or at least about 100 m²/g.

[0061] In some embodiments, the electrolyte removing component comprises a single metal oxide. In some embodiments, the electrolyte removing component comprises a mixture of at least two different metal oxides. In some embodiments, the electrolyte removing component comprises a mixture of at least three different metal oxides. In some embodiments, the electrolyte removing component comprises doped metal oxide(s).

[0062] In some embodiments, the electrolyte removing component comprises alkaline earth metal oxide(s). In some embodiments, the electrolyte removing component comprises transition metal oxide(s). In some embodiments, the electrolyte removing component comprises post transition metal oxide(s). In some embodiments, the electrolyte removing component comprises rear earth metal oxide(s).

[0063] In some embodiments, the electrolyte removing component comprises aluminum oxide, titanium oxide, zirconium oxide, tungsten oxide, a doped oxide thereof, or a mixture thereof. [0064] In some embodiments, the supported catalyst further comprises an electrolyte repelling component to prevent electrolyte from contacting the catalyst, wherein the electrolyte repelling component comprises at least one of graphite, carbide and nitride.

[0065] In some embodiments, the electrolyte repelling component is in the form of an electrolyte repelling layer coating the thermally stable core to form a core shell structure. In some embodiments, the electrolyte repelling component is mixed with or dispersed in the thermally stable core.

[0066] In some embodiments, the electrolyte repelling component comprises a single material. In some embodiments, the electrolyte repelling component comprises a mixture of at least two different materials. In some embodiments, the electrolyte repelling component comprises a mixture of at least three different materials. In some embodiments, the electrolyte repelling component comprises graphite.

[0067] In some embodiments, the electrolyte repelling component comprises one or more metal carbide(s). In some embodiments, the electrolyte repelling component comprises transition metal carbide(s). In some embodiments, the electrolyte repelling component comprises post transition metal carbide(s). In some embodiments, the electrolyte repelling component comprises rare earth metal carbide(s).

[0068] In some embodiments, the electrolyte repelling component comprises one or more metal nitride(s). In some embodiments, the electrolyte repelling component comprises transition metal nitride(s). In some embodiments, the electrolyte repelling component comprises post transition metal nitride(s). In some embodiments, the electrolyte repelling component comprises rare earth metal nitride(s).

[0069] In some embodiments, the supported catalyst further comprises an electrolyte removing layer coating the thermally stable core and an electrolyte repelling layer coating the electrolyte removing layer, wherein the electrolyte removing layer comprises at least one metal oxide, and wherein the electrolyte repelling layer comprises at least one of graphite, carbide, or nitride.

[0070] In some embodiments, the supported catalyst is not coated by a silicate-containing layer. [0071] Furthermore, many embodiments of the invention relate to a molten carbonate fuel cell comprising the supported catalyst described herein as a direct internal reforming catalyst.

[0072] FIG. 4 illustrates the relative catalyst activity over time for a baseline DIR catalyst and a DIR catalyst having a thermally stabilized support disclosed herein. Differences in catalyst activity are seen after approximately 100 hours of usage. In some embodiments, the direct internal reforming catalyst in the molten carbonate fuel cell retains at least about 50%, or at least about 60%), or at least about 70% of its initial catalytic activity after 200 hours of accelerated testing (e.g., to simulate aging in a fuel cell stack). In some embodiments, the direct internal reforming catalyst in the molten carbonate fuel cell retains at least about 50%, or at least about 60%), or at least about 70% of its initial catalytic activity after 500 hours of accelerated testing. In some embodiments, the direct internal reforming catalyst in the molten carbonate fuel cell retains at least about 50%, or at least about 60%, or at least about 70% of its initial catalytic activity after 700 hours of accelerated testing.

[0073] Catalyst aging can be caused by sintering of Ni catalyst, coverage of the catalyst by electrolyte, sintering of support creating large internal pores which causes electrolyte to penetrate deep inside, and blockage of pores by electrolyte deposited on the pores. Known production methods do not address these deactivation mechanisms and therefore cannot provide a stable catalyst to achieve a fuel cell life of 7-10 years. For example, the most common approach involves co-precipitation of Ni and the support for ease of manufacturing and provides uniform distribution of Ni and support. The disadvantage of this approach is sintering of both support and Ni during service, which causes collapse of structure, blockage of pores and access to Ni, which then leads to loss of activity.

[0074] The supported catalyst described here can be synthesized in at least two different ways. One is to coat electrolyte removing or repelling materials onto catalyst made through co- precipitation after heat treatment. The second way is to deposit Ni onto stable (pre-sintered) support which may also include transition and/or rare earth metals. This catalyst core can then be coated with electrolyte removing or repelling materials.

Indirect Internal Reformer Catalyst Arrangement [0075] Arrangement of the catalyst in the IIR in a fuel cell stack with a low activity high stability DIR catalyst should ensure higher and relatively constant over time heat removal from the anode inlet region of the cells and also target higher hydrocarbon conversion in the IIR. Higher hydrocarbon conversion in the IIR will reduce the amount of reforming to be performed in the DIR. Higher hydrocarbon conversion in the IIR can be achieved by reducing the number of open channels where fuel can slip through without reforming. With less active DIR catalyst, more catalyst is needed in the IIR at the anode inlet region to maximize fuel reforming in the IIR and greater reforming cooling via the IIR. The IIR catalyst loading is designed to increase IIR reforming near the anode inlet region over the baseline design.

[0076] FIG. 5 is a schematic diagram showing a fuel flow over catalyst bed regions in an IIR according to an embodiment of the invention. The flow of fuel through the IIR has a U-shaped flow pattern. Fuel enters the reformer from the plenum at the anode inlet near corner A. Gas flow turns around the baffle near the anode outlet near corner D and flows backwards through the reforming catalyst beds towards the anode inlet between corners A and B. Catalyst bed is divided into different zones for classification and discussion purpose. Zones 4 and 5, which are close to the anode inlet region (between corners A and B), have more catalyst and less open channels to maximize reforming conversion in the IIR and provide improved cooling to the anode inlet region. The number of open channels in zones 4 and 5 may also be optimized to decouple temperature of the anode inlet region and the reforming conversion in the IIR. Less catalyst is needed in the IIR at the anode outlet region than in the anode inlet region, to minimize cooling in the anode outlet region of the fuel cell stack. The reduced catalyst in the anode outlet region raises the anode outlet region temperature and enables more complete reforming conversion of the hydrocarbon fuel. Zones 1 and 2 have less reforming catalyst to reduce the heat removal and raise anode outlet temperature between corners C and D. One illustrative example would have 5 zones of equal length between anode inlet and the anode outlet, with zones 1 and 2 having 5% and 10% respectively of the total catalyst and Zones 3, 4, and 5 having 20%), 25%), and 40% respectively of the total catalyst in the IIR. Other catalyst distributions are also possible depending on the activity of the DIR catalyst to ensure small differential temperatures within the stack during operation of the stack.

[0077] FIG. 6A is a CFD simulation showing the change in temperature in the cell plane of a fuel cell when using a baseline DIR catalyst over the life of the fuel cell, assuming 100%> activity at beginning of life (BOL) 20% activity at end of life (EOL), and FIG. 6B is a CFD simulation showing the change in temperature in the cell plane of a fuel cell over the life of the fuel cell when using a low activity, high stability DIR catalyst according to an embodiment of the present invention, assuming 50% activity at BOL and 15% activity at EOL. The IIR catalyst arrangement according to an embodiment of the invention reaches targeted temperature distributions at start of operation and also meets the end of operation targets much easily compared to baseline design, which in turn implies that life extension can be achieved. It can be seen from FIGS. 6 A and 6B that, as the stack ages, there is temperature rise at the anode inlet region and a temperature drop at the anode outlet region. When using less active more stable DIR catalyst, this temperature change is reduced, allowing the stack to tolerate more

deactivation of the DIR catalyst, in other words extending stack life.

Direct Internal Reformer Catalyst Arrangement

[0078] Arrangement of catalyst in the DIR can be modified to improve contact of fuel in the anode inlet region.

[0079] One such arrangement involves a staggered pattern of catalyst pellets, where fuel has to move between catalyst pellets to reach open areas in the flow channel, as shown in FIG. 7. This arrangement increases the contact time of the gas with the DIR catalyst relative to an un- staggered arrangement where gas has a clear straight flow path. Increased residence time allows more time for reforming, which may be beneficial with a reduced activity DIR catalyst.

[0080] Another arrangement for increasing residence time of the fuel in the anode chamber and enhancing contact with the DIR catalyst is shown in FIG. 8, where perforated baffles are used to direct fuel flow through a serpentine path in the anode chamber. Perforated baffles avoid dead zones in the cell and ensure a more uniform current density distribution.

[0081] In all cases it is understood that the above-described arrangements are merely illustrative of the many possible specific embodiments which represent applications of the present invention. Numerous and varied other arrangements, including use of different electrolytes, can be readily devised in accordance with the principles of the present invention without departing from the spirit and scope of the invention. [0082] As utilized herein, the terms "approximately," "about," "substantially", and similar terms are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. It should be understood by those of skill in the art who review this disclosure that these terms are intended to allow a description of certain features described and claimed without restricting the scope of these features to the precise numerical ranges provided. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and claimed are considered to be within the scope of the invention as recited in the appended claims.

[0083] The terms "coupled," "connected," and the like as used herein mean the joining of two members directly or indirectly to one another. Such joining may be stationary (e.g., permanent) or moveable (e.g., removable or releasable). Such joining may be achieved with the two members or the two members and any additional intermediate members being integrally formed as a single unitary body with one another or with the two members or the two members and any additional intermediate members being attached to one another.

[0084] References herein to the positions of elements (e.g., "top," "bottom," "above,"

"below," etc.) are merely used to describe the orientation of various elements in the Figures. It should be noted that the orientation of various elements may differ according to other exemplary embodiments, and that such variations are intended to be encompassed by the present disclosure.

[0085] It is important to note that the construction and arrangement of the various exemplary embodiments are illustrative only. Although only a few embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter described herein. For example, elements shown as integrally formed may be constructed of multiple parts or elements, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. The order or sequence of any process or method steps may be varied or re- sequenced according to alternative embodiments. Other substitutions, modifications, changes and omissions may also be made in the design, operating conditions and arrangement of the various exemplary embodiments without departing from the scope of the present invention. For example, perforated baffles may be further optimized to achieve the intent of increasing residence time without creating dead zones.

Claims

WHAT IS CLAIMED IS:

1. A reforming catalyst, comprising:

a thermally stable core; and

an electrolyte removing component and/or an electrolyte repelling component; wherein the thermally stable core comprises a metal oxide support and nickel disposed in the metal oxide support.

2. The reforming catalyst of claim 1, wherein:

the metal oxide support comprises:

at least one base metal oxide or ceramic material, and

at least one transition metal oxide or rare earth metal oxide dispersed in the base metal oxide or ceramic material.

3. The reforming catalyst of claim 1, wherein the metal oxide support has a surface area in a range of 5 m²/g to 120 m²/g.

4. The reforming catalyst of claim 1, wherein the nickel has a weight concentration in a range of 10 wt.% to 50 wt.% of the reforming catalyst.

5. The reforming catalyst of claim 1, wherein the metal oxide support is a pre- sintered metal oxide support comprising at least one transition metal oxide or rare earth metal oxide.

6. The reforming catalyst of claim 1, wherein the thermally stable core has a mean pore diameter in a range of 65 A to 50θΑ and a pore size distribution standard deviation of less than 50%.

7. The reforming catalyst of claim 1, wherein:

the reforming catalyst comprises the electrolyte removing component; and the electrolyte removing component is an electrolyte removing layer coating the thermally stable core to form a core-shell structure.

8 The reforming catalyst of claim 1, wherein:

the reforming catalyst comprises the electrolyte removing component; and the electrolyte removing component is dispersed in the thermally stable core.

9. The reforming catalyst of claim 1, wherein:

the reforming catalyst comprises the electrolyte removing component; and the electrolyte removing component comprises at least one of aluminum oxide, titanium oxide, zirconium oxide, tungsten oxide, or a mixture thereof.

10. The reforming catalyst of claim 1, wherein:

the reforming catalyst comprises the electrolyte repelling component; and the electrolyte repelling component is an electrolyte repelling layer coating the thermally stable core to form a core-shell structure.

11. The reforming catalyst of claim 1, wherein:

the reforming catalyst comprises the electrolyte repelling component; and the electrolyte repelling component is dispersed in the thermally stable core.

12. The reforming catalyst of claim 1, wherein:

the reforming catalyst comprises the electrolyte repelling component; and the electrolyte repelling component comprises at least one of graphite, a metal carbide, a metal nitride, or a mixture thereof.

13. The reforming catalyst of claim 1, wherein the reforming catalyst comprises both the electrolyte removing component and the electrolyte repelling component.

14. The reforming catalyst of claim 13, wherein the electrolyte removing component is an electrolyte removing layer coating the thermally stable core and wherein the electrolyte repelling component is an electrolyte repelling layer coating the electrolyte removing layer.

15. The reforming catalyst of claim 14, wherein:

the electrolyte removing component comprises at least one of aluminum oxide, titanium oxide, zirconium oxide, tungsten oxide, or a mixture thereof; and the electrolyte repelling component comprises at least one of graphite, a metal carbide, a metal nitride, or a mixture thereof.

16. A molten carbonate fuel cell having direct internal reforming, the molten carbonate fuel cell comprising:

an anode compartment; and

the reforming catalyst of any one of claims 1-15, disposed in the anode compartment.