ANODE CATALYSTS FOR FUEL CELLS

Abstract

A fuel cell comprising a Ni-based anode. The fuel cell also comprises a catalyst, wherein the catalyst comprises a mixture of: NiO, YSZ, BaCO.sub.3, CuO, ZnO, Fe.sub.2O.sub.3, and Cr.sub.2O.sub.3. It is envisioned that the fuel cell is operated at temperatures greater than 600° C.

Claims

1. A fuel cell comprising: a Ni-based anode; a catalyst, wherein the catalyst comprises a mixture of: NiO, YSZ, BaCO.sub.3, CuO, ZnO, Fe.sub.2O.sub.3, and Cr.sub.2O.sub.3; wherein the fuel cell is operated at temperatures greater than 600° C.

2. The fuel cell of claim 1, wherein the catalyst is incorporated into the anode.

3. The fuel cell of claim 1, wherein the catalyst is layered onto the anode subjacent the anode and superjacent an electrolyte.

4. The fuel cell of claim 1, wherein fuel cell is operated at temperature lower than 750° C.

5. The fuel cell of claim 1, wherein wt % ratio of BaCO.sub.3 in the catalyst ranges from about 1% to about 5%.

6. The fuel cell of claim 1, wherein wt % ratio of CuO in the catalyst ranges from about 1% to about 5%.

7. The fuel cell of claim 1, wherein wt % ratio of ZnO in the catalyst ranges from about 1% to about 5%.

8. The fuel cell of claim 1, wherein wt % ratio of Fe.sub.2O.sub.3 in the catalyst ranges from about 3% to about 5%.

9. The fuel cell of claim 1, wherein wt % ratio of Cr.sub.2CO.sub.3 in the catalyst ranges is less than 1%.

10. The fuel cell of claim 1, wherein during the formation of the catalyst, the catalyst was annealed at 1200° C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] A more complete understanding of the present invention and benefits thereof may be acquired by referring to the follow description taken in conjunction with the accompanying drawings in which:

[0013] FIG. 1 depicts a methane conversation as a function of temperature with a methane flow rate of 100 sccm and a steam-to-carbon ratio of 2:1.

[0014] FIG. 2 depicts a methane conversation as a function of temperature with a methane flow rate of 200 sccm and a steam-to-carbon ratio of 2:1.

[0015] FIG. 3 depicts a methane conversation as a function of temperature with a methane flow rate of 400 sccm and a steam-to-carbon ratio of 2:1.

[0016] FIG. 4 depicts a reforming catalyst layer on fuel cells anode surface.

[0017] FIG. 5 depicts the fuel cell power output testing results at 0.8V on natural gas feed with a steam-to-carbon ratio of 2:1.

DETAILED DESCRIPTION

[0018] Turning now to the detailed description of the preferred arrangement or arrangements of the present invention, it should be understood that the inventive features and concepts may be manifested in other arrangements and that the scope of the invention is not limited to the embodiments described or illustrated. The scope of the invention is intended only to be limited by the scope of the claims that follow.

[0019] The present embodiment describes a fuel cell comprising a Ni-based anode. The fuel cell also comprises a catalyst, wherein the catalyst or catalyst layer comprises a mixture of: NiO, YSZ, BaCO.sub.3, CuO, ZnO, Fe.sub.2O.sub.3, and Cr.sub.2O.sub.3. In this embodiment, it is envisioned that the fuel cell is operates at temperatures greater than 600° C.

[0020] The following examples of certain embodiments of the invention are given. Each example is provided by way of explanation of the invention, one of many embodiments of the invention, and the following examples should not be read to limit, or define, the scope of the invention.

Sample Preparation

[0021] Table 1 depicts compositions for catalyst samples that were tested. The baseline composition (sample 1) consisted of 60 g NiO and 40 g YSZ powder.

TABLE-US-00001 TABLE 1 Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 NiO 60 60 60 60 60 YSZ 40 40 40 40 40 BaCO.sub.3 1.5 1.5 5.0 1.5 CuO 1.650 1.650 ZnO 1.700 1.700 Fe.sub.2O.sub.3 4.375 4.375 Cr.sub.2O.sub.3 0.610 0.610

[0022] The weight ratio 0% of the catalysts are shown below in Table 2

TABLE-US-00002 TABLE 2 Preferred Optimal Weight ratio % weight ratio weight ratio BaCO.sub.3 0.5-10 wt % 1-5 wt % 1.3-1.5 wt % CuO 0.5-10 wt % 1-5 wt % 1.4-1.6 wt % ZnO 0.5-10 wt % 1-5 wt % 1.4-1.6 wt % Fe.sub.2O.sub.3 Greater than 3 wt % 3-5 wt % 3.5-4.5 wt % Cr.sub.2O.sub.3 Less than 1 wt % Less than 0.8 wt % 0.5-0.6 wt %

[0023] During the formation of the samples, the catalyst was pre-mixed and annealed at 1200° C. for at least 2 hours prior to use.

Offline Testing Results

[0024] Five grams of each catalyst sample was held in a tubular reactor located in a furnace. A mixture of methane and steam at a pre-determined ratio was introduced to the reactor and part of the exhaust was directed to a GC for real-time monitoring of the off-gas composition.

[0025] Samples were heated from room temperature to 750° C. at a rate of 3° C./min under nitrogen. When the reaction temperature was reached, the sample was reduced at 750° C. with hydrogen. after reduction, dry methane was bubbled through a heated humidifier at different flow rates (100-400 sccm). The temperature of the humidifier was set at 89° C. to generate a steam-to-carbon ratio of 2:1. GC data were collected from 750° C. to 500° C. at an interval of 50° C.

[0026] FIG. 1 depicts a methane conversation as a function of temperature with a methane flow rate of 100 sccm and a steam-to-carbon ratio of 2:1.

[0027] FIG. 2 depicts a methane conversation as a function of temperature with a methane flow rate of 200 sccm and a steam-to-carbon ratio of 2:1.

[0028] FIG. 3 depicts a Methane conversation as a function of temperature with a methane flow rate of 400 sccm and a steam-to-carbon ratio of 2:1.

Fuel Cell Testing Results

[0029] Samples 3 and 5 were selected for fuel cell testing. The catalysts could simply be mixed with the raw anode powders during cell fabrication or layered onto the anode via spray coating or screen printing as shown in FIG. 4. The catalyst coatings on the fuel cell were annealed at 1200° C. for 2 hours prior to fuel cell testing.

[0030] Electrochemical testing was carried out at 600 to 700° C. Natural gas was used as the fuel (0.12 L/min) and ambient air (1.2 L/min) was flowed across the cathode surface. A consist steam-to-carbon ratio of 2:1 was used in all fuel cell tests. FIG. 5 shows the fuel cell power output testing results at 0.8V on natural gas feed with a steam-to-carbon ratio of 2:1. Compared with the baseline cell, catalyst #3 (Cu—Zn—Ba) improved fuel cell performance by 26%, 19%, and 13% at 600, 650, and 700° C., respectively on natural gas fuel, while #5 catalyst (Cu—Zn—Fe—Cr—Ba) improved fuel cell performance by 18%, 24%, and 23% at these temperatures.

[0031] In closing, it should be noted that the discussion of any reference is not an admission that it is prior art to the present invention, especially any reference that may have a publication date after the priority date of this application. At the same time, each and every claim below is hereby incorporated into this detailed description or specification as an additional embodiment of the present invention.

[0032] Although the systems and processes described herein have been described in detail, it should be understood that various changes, substitutions, and alterations can be made without departing from the spirit and scope of the invention as defined by the following claims. Those skilled in the art may be able to study the preferred embodiments and identify other ways to practice the invention that are not exactly as described herein. It is the intent of the inventors that variations and equivalents of the invention are within the scope of the claims while the description, abstract and drawings are not to be used to limit the scope of the invention. The invention is specifically intended to be as broad as the claims below and their equivalents.