Operation of Molten Carbonate Fuel Cells With Enhanced CO2 Utilization

Patent metadata

Field	Value
Publication number	US-2020176789-A1
Application number	US-201916695281-A
Country	US
Kind code	A1
Filing date	Nov 26, 2019
Priority date	Nov 30, 2018
Publication date	Jun 4, 2020
Grant date	—

Abstract

Molten carbonate fuel cells (MCFCs) are operated to provide enhanced CO2 utilization. This can increase the effective amount of carbonate ion transport that is achieved. The enhanced CO2 utilization is enabled in part by operating an MCFC under conditions that cause transport of alternative ions across the electrolyte. The amount of alternative ion transport that occurs during enhanced CO2 utilization can be mitigated by using a more acidic electrolyte.

First claim

1 . A method for producing electricity in a molten carbonate fuel cell comprising an electrolyte, the method comprising: operating a molten carbonate fuel cell comprising an anode and a cathode at a transference of 0.95 or less and an average current density of 60 mA/cm 2 or more, to generate 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 O 2 , and 1.0 vol % or more H 2 O.

2 . The method of claim 1 , wherein operating the molten carbonate fuel cell further comprises operating at a measured CO 2 utilization of 75% or more, a cathode input stream having a CO 2 concentration of 10 vol % or less, or a combination thereof.

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

4 . The method of claim 1 , wherein the transference is 0.90 or less.

5 . The method of claim 1 , wherein the electrolyte is more acidic than an electrolyte composed of (Li 0.52 Na 048 ) 2 CO 3 .

6 . The method of claim 1 , wherein the electrolyte comprises Li and one or more additional alkali metals, the electrolyte comprising a greater molar amount of the one or more additional alkali metals than a molar amount of Li.

7 . The method of claim 1 , wherein 33% or more of a molar amount of alkali metal in the electrolyte comprises potassium.

8 . The method of claim 1 , wherein the current density is 150 mA/cm 2 or more.

9 . The method of claim 1 , wherein the voltage drop across the cathode is 0.4 V or less, or wherein the electricity is generated at a voltage of 0.55 V or more, or a combination thereof.

10 . The method of claim 1 , wherein a fuel utilization in the anode is 60% or more, or wherein a fuel utilization in the anode is 55% or less.

11 . The method of claim 1 , wherein a H 2 concentration in the anode exhaust is 5.0 vol % or more, or wherein a combined concentration of H 2 and CO in the anode exhaust is 6.0 vol % or more, or a combination thereof.

12 . The method of claim 1 , wherein the fuel cell is operated at a thermal ratio of 0.25 to 1.0.

13 . The method of claim 1 , wherein an amount of a reformable fuel introduced into the anode, into a reforming element associated with the anode, or a combination thereof, is at least about 75% greater than the amount of hydrogen reacted in the molten carbonate fuel cell to generate electricity.

14 . The method of claim 1 , further comprising:
introducing an anode input stream into the anode of a molten carbonate fuel cell; and introducing a cathode input stream comprising O 2 , CO 2 , and H 2 O into the cathode of the molten carbonate fuel cell.

15 . A method for producing electricity in a molten carbonate fuel cell comprising an electrolyte, the method comprising: operating a molten carbonate fuel cell comprising an anode, a cathode, and an electrolyte that is more acidic than an electrolyte composed of (Li 0.52 Na 0.48 ) 2 CO 3 , at a transference of 0.97 or less and an average current density of 60 mA/cm 2 or more, to generate 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 O 2 , and 1.0 vol % or more H 2 O.

16 . The method of claim 15 , wherein the electrolyte comprises Li and one or more additional alkali metals, the electrolyte comprising a greater molar amount of the one or more additional alkali metals than a molar amount of Li.

17 . The method of claim 15 , wherein 33% or more of a molar amount of alkali metal in the electrolyte comprises potassium.

18 . The method of claim 15 , wherein operating the molten carbonate fuel cell further comprises operating at a measured CO 2 utilization of 75% or more, a cathode input stream having a CO 2 concentration of 10 vol % or less, or a combination thereof.

19 . The method of claim 18 , wherein the cathode input stream comprises 5.0 vol % or less of CO 2 , or wherein the cathode exhaust comprises 1.0 vol % or less of CO 2 , or a combination thereof.

20 . The method of claim 15 , wherein the transference is 0.90 or less.

Assignees

• Exxonmobil Res & Eng Co
• Fuelcell Energy Inc

Inventors

• Hilmi Abdelkader
• Barckholtz Timothy A
• Rosen Jonathan
• Elsen Heather A
• Kiss Gabor
• Willman Carl A
• Yuh Chao-Yi
• Ghezel-Ayagh Hossein
• Geary Timothy C

Classifications

• H01M8/04753

  of fuel cell reactants · CPC title

• H01M8/145

  comprising carbonates · CPC title

• H01M2008/147

  Fuel cells with molten carbonates · CPC title

• H01M8/04179 Primary

  by purging or increasing flow or pressure of reactants · CPC title

• H01M2300/0051

  Carbonates · CPC title