Molten carbonate fuel cells internal reforming

Autothermal or steam reforming of methane was considered in thermodynamic calculations by Cavallaro and Freni for reformers, which were integrated into a molten carbonate fuel cell [43]. Direct or indirect internal reforming is possible within the molten carbonate fuel cell. The reforming may be performed either by the anode itself or by a dedicated catalyst in the anode compartment in analogy with the solid oxide fuel cell, as has been explained above. Direct reforming of alcohol fuels is also possible in molten carbonate fuel cells [44], whereas processing of liquid hydrocarbons requires a pre-reformer. 

Cavallaro, S. Freni, S., Ethanol steam reforming in a molten carbonate fuel cell. A preliminary kinetic investigation. International Journal of Hydrogen Energy 1996, 21, 465-469. 

S. Kaneko et al., "Research on On-Site Internal Reforming Molten Carbonate Fuel Cell," 1989 Intemational Gas Research Conference, 1989. 

T. Tanaka, et al., "Development of Internal Reforming Molten Carbonate Fuel Cell Technology," in Proceedings of the 25th lECEC, American Institute of Chemical Engineers, New York, NY, August 1990. 

First, we will refer to the direct use of hydrocarbon fuels in an SOFC as direct utilization rather than direct oxidation. Second, we recognize that the broadest definition of direct utilization, exclusive from mechanistic considerations, should include rather conventional use of fuel by internal reforming, with steam being cofed to the fuel cell with the hydrocarbon. Indeed, this nomenclature has been used for many years with molten-carbonate fuel cells. However, because internal reforming is essentially limited to methane and because the addition of steam with the fuel adds significant system complexity, we will focus primarily on systems and materials in which the hydrocarbons are fed to the fuel cell directly without significant amounts of water or oxygen. 

Fig. 2.1. Working principle of the Molten Carbonate Fuel Cell (MCFC) with direct internal reforming (DIR).

The internal reforming molten carbonate fuel cell has a particular construction. In the anode chamber there is a catalyst for the reforming reaction of natural... 

Gonjyo, Y. Matsumura, M. Tanaka, T. Performance of direct internal reforming molten carbonate fuel cells. Proceedings of the 26 ... 

Cavallaro, S. Mondello, N. Freni, S. Hydrogen produced from ethanol for internal reforming molten carbonate fuel cell. J. Power Sources 2001, 102 (1-2), 198-204. 

Molten carbonate fuel cells use a molten salt electrolyte of lithium and potassium carbonates and operate at about 650 °C. MCFCs promise high fuel-to-electricity efficiencies and the ability to consume coal-based fuels. A further advantage of the MCFC is the possibility of internal reforming due to the high operating temperatures (600-700 °C) and of using the waste heat in combined cycle power plants. 

The direct carbonate fuel cell is a variant of molten carbonate fuel cells (MCFC) in that it internally reforms methane-containing fuels within the anode compartment of the fuel cell (Matsumoto et al., 1990 Farooque, 1991 Sasaki et al., 1993 Shinoki et al., 1995). The largest demonstration of MCFC technology has been California s 2-MW Santa Clara Demonstration Project (Fuel Cell Engineering Corporation, 1997). 

Shinoki T., Matsumura M., Sasaki A., 1995. Development of an internal reforming molten carbonate fuel cell stack, IEEE Trans. Energy Conversion Vol. 10, No. 4, pp. 111-119. 

Heldebrecht, P. and Sundmacher, K. (2005) Dynamic model of a cross-flow molten carbonate fuel cell with direct internal reforming. J. Electrochem. Soc., 152 (11), A2217-A2228. 

Molten Carbonate Fuel Cells (MCFCs). MCFCs use an electrolyte composed of a molten carbonate salt mixture suspended in a porous, chemically inert ceramic matrix. Like SOFGs, MCFCs do not require an external reformer to convert fuels to hydrogen. Because of the high operating temperatures, these fuels are converted to hydrogen within the fuel cell itself by an internal re-forming process. 

Theoretical calculations to evaluate internal reforming of methanol, ethanol and methane for molten carbonate fuel cells were performed by Maggio et al. [45]. 

In a conventional fuel cell system, a carbonaceous fuel is fed to a fuel processor where it is steam reformed to produce H2 (as well as other products, CO and CO2, for example), which is then introduced into the fuel cell and electrochemically oxidized. The internal reforming molten carbonate fuel cell, however, eliminates the need for a separate fuel processor for reforming... 

All of the above-mentioned solid electrolytes are oxygen conductors. An automatic consequence of this is that, as in molten carbonate fuel cells, the products of electrochemical reactions all end up on the anode side. While is beneficial for internal reforming and water gas shift reaction (which utilizes the water produced as a reactant), it dilutes the fuel, and at high utilization it can significantly reduce the Nernst potential. 

Zhang J, Zhang X, Liu W, Liu H, Qiu J, Yeung KL (2014) A new alkaU-resistant Ni/A1203-MSU-1 core-shell catalyst for methane steam reforming in a direct internal reforming molten carbonate fuel cell. J Power Sources 246 74—83... 

Baker B, Bums D, Lee C, Mam H, Patel P (1981) Internal reforming for natural gas-fueled molten-carbonate fuel cells. Report 107. (90-6194-(13), GRI-80/0126 Order No. PB82-200676)... 

Kim H, Cho JH, Lee KS (2013) Detailed dynamic modeling of a molten carbonate fuel cell stack with indirect internal reformers. Euel Cells 13 259-269... 

Pfafferodt M, Heidebrecht P, Sundmacher K, Wuerteirbeiger U, Bednatz M (2008) Multiscale Simulation of the Indirect Internal Reforming Unit (HR) in a Molten Carbonate Fuel Cell (MCFC). Ind Eng Chem Res 47 4332- 341... 

Freni S, Aquino M, Passalacqua E (1994) Molten carbonate fuel cell with indirect internal reforming. J Power Sources 52 41-47... 

Miyazaki M, Okada T, Ide H, Matsumoto S, Shinoki T, Ohtsuki J (1992) Development of an indirect internal reforming molten carbonate fuel cell stack. In Proceedings of the Intersociety Energy Conversion Engineering Conference, 27th(3), vol 3. 287-3.292... 

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