Reforming Catalyst Pattern For Fuel Cell Operated With Enhanced CO2 Utilization

Patent metadata

Field	Value
Publication number	US-2020176800-A1
Application number	US-201916696821-A
Country	US
Kind code	A1
Filing date	Nov 26, 2019
Priority date	Nov 30, 2018
Publication date	Jun 4, 2020
Grant date	—

Abstract

A reforming element for a molten carbonate fuel cell stack and corresponding methods are provided that can reduce or minimize temperature differences within the fuel cell stack when operating the fuel cell stack with enhanced CO2 utilization. The reforming element can include at least one surface with a reforming catalyst deposited on the surface. A difference between the minimum and maximum reforming catalyst density and/or activity on a first portion of the at least one surface can be 20% to 75%, with the highest catalyst densities and/or activities being in proximity to the side of the fuel cell stack corresponding to at least one of the anode inlet and the cathode inlet.

First claim

1 . A method for producing electricity, the method comprising:
passing a fuel stream comprising a reformable fuel into a fuel stack comprising a first surface, the first surface comprising a first portion comprising a reforming catalyst, a reforming catalyst density on the first portion of the first surface having a difference between a maximum catalyst density and a minimum catalyst density of 20% to 75%; reforming at least a portion of the reformable fuel in the presence of the first surface to produce reformed hydrogen; introducing at least a portion of the reformable fuel, at least a portion of the reformed hydrogen, or a combination thereof into an anode of a molten carbonate fuel cell; introducing a cathode input stream comprising O 2 and CO 2 into a cathode of the molten carbonate fuel cell, a direction of flow in the cathode of the molten carbonate fuel cell being substantially orthogonal to a direction of flow in the anode of the molten carbonate fuel cell; and operating the molten carbonate fuel cell at a transference of 0.97 or less and an average current density of 60 mA/cm 2 or more to generate electricity, an anode exhaust comprising H 2 , CO, and CO 2 , and a cathode exhaust comprising 2.0 vol % or less CO 2 , 1.0 vol % or more H 2 O, and 1.0 vol % or more O 2 .

2 . The method of claim 1 , wherein the reforming catalyst on the first portion of the first surface comprises a monotonic catalyst density variation.

3 . The method of claim 1 , wherein the maximum catalyst density is in proximity to the anode inlet, or wherein the maximum catalyst density is in proximity to the cathode inlet.

4 . The method of claim 1 , wherein the minimum catalyst density is in proximity to the anode outlet, or wherein the minimum catalyst density is in proximity to the cathode outlet.

5 . The method of claim 1 , wherein the fuel cell stack comprises a reforming element associated with the anode, wherein the first surface comprises an interior surface of the reforming element.

6 . The method of claim 5 , wherein a temperature variation within the fuel cell stack at a separator plate between the reforming element and the anode is 70° C. or less.

7 . The method of claim 1 , wherein the first surface comprises an interior surface of the anode.

8 . The method of claim 7 , wherein a temperature variation within the fuel cell stack at a separator plate between the anode and another element is 70° C. or less.

9 . The method of claim 1 , wherein the first surface further comprises a second portion.

10 . The method of claim 9 , wherein the second portion is in proximity to the cathode inlet, or wherein the second portion is in proximity to the anode inlet.

11 . The method of claim 9 , wherein the second portion comprises a constant catalyst density.

12 . The method of claim 1 , wherein the cathode input stream comprises 5.0 vol % or less CO 2 , or wherein the cathode exhaust comprises 1.0 vol % or less CO 2 , or a combination thereof.

13 . The method of claim 1 , wherein the transference is 0.95 or less

14 . A method for producing electricity, the method comprising:
passing a fuel stream comprising a reformable fuel into a fuel stack comprising a first surface, the first surface comprising a first portion comprising a reforming catalyst, a reforming catalyst density on the first portion of the first surface having a difference between a maximum catalyst activity and a minimum catalyst activity of 20% to 75%; reforming at least a portion of the reformable fuel in the presence of the first surface to produce reformed hydrogen; introducing at least a portion of the reformable fuel, at least a portion of the reformed hydrogen, or a combination thereof into an anode of a molten carbonate fuel cell; introducing a cathode input stream comprising O 2 and CO 2 into a cathode of the molten carbonate fuel cell, a direction of flow in the cathode of the molten carbonate fuel cell being substantially orthogonal to a direction of flow in the anode of the molten carbonate fuel cell; and operating the molten carbonate fuel cell at a transference of 0.97 or less and an average current density of 60 mA/cm 2 or more to generate electricity, an anode exhaust comprising H 2 , CO, and CO 2 , and a cathode exhaust comprising 2.0 vol % or less CO 2 , 1.0 vol % or more H 2 O, and 1.0 vol % or more O 2 .

15 . The method of claim 14 , wherein the reforming catalyst comprises a plurality of lines of catalyst particles, and wherein reforming the at least a portion of the reformable fuel comprises flowing the at least a portion of the reformable fuel over the catalyst particles in a direction that is substantially parallel to the lines of catalyst particles.

16 . A fuel cell stack comprising:
a molten carbonate fuel cell comprising an anode and a cathode; a reforming element associated with the anode, the reforming element comprising a first surface, the first surface comprising a first portion comprising a reforming catalyst, a reforming catalyst density on the first portion of the first surface comprising a monotonically decreasing catalyst density, the reforming catalyst density on the first portion of the first surface having a difference between a maximum catalyst density and a minimum catalyst density of 20% to 75%; and a separator plate between the anode and the reforming element.

17 . The fuel cell stack of claim 16 , wherein the maximum catalyst density is in proximity to the anode inlet, or wherein the maximum catalyst density is in proximity to the cathode inlet.

18 . The fuel cell stack of claim 16 , wherein the minimum catalyst density is in proximity to the anode outlet, or wherein the minimum catalyst density is in proximity to the cathode outlet.

19 . The fuel cell stack of claim 16 , wherein the first surface further comprises a second portion, the second portion being in proximity to the cathode inlet or in proximity to the anode inlet, the second portion comprising a constant catalyst density.

20 . The fuel cell stack of claim 16 , wherein the reforming catalyst comprises substantially parallel lines of catalyst particles.

Assignees

• Exxonmobil Res & Eng Co
• Fuelcell Energy Inc

Inventors

• O'Neal Everett J
• Han Lu
• Pereira Carla S
• Blanco Gutierrez Rodrigo F
• Healy Timothy M
• Willman Carl A
• Ghezel-Ayagh Hossein
• Dobek Jr Frank J

Classifications

• H01M2008/147

  Fuel cells with molten carbonates · CPC title

• H01M8/145 Primary

  comprising carbonates · CPC title

• H01M8/0618

  Reforming processes, e.g. autothermal, partial oxidation or steam reforming · CPC title

• H01M2300/0051

  Carbonates · CPC title

• H01M8/14

  Fuel cells with fused electrolytes · CPC title