High-temperature PEMFC

The product composition from the fuel reformer generally consists of 35 to 40% H2 and 6 to 10% CO balanced with H20, C02, and N2 [39], The CO is further reduced to 2 to 3% by HT WGS and then down to <0.5% CO with LT WGS. It is not possible to reduce the concentration of CO down to a few ppm with LT WGS because of equilibrium constraints. This has to be done with preferential oxidation of CO in the last step. However, owing to the development of high-temperature PEMFC... 

High-temperature PEMFC Stack with Methanol Reforming (AMFC) (Volvo (S), Technical University of Denmark (DK), Statoil (N), NTNU (N), University of Newscastle-Upon-Tyne (UK), Proton Motor Fuel Cell (D)). 

Zhai, Y. et al.. Degradation study on MEA in H3PO4/PBI high-temperature PEMFC life test, J. Electrochem. Soc., 154, B72, 2007. 

The ionic conductivities of sulfonated polyetherketone/imidazole (pyrazole) systems were first studied by Kreuer et al. [161]. The intercalation of imidazole (pyrazole) into the polymer with Bronsted add functions was shown to produce a high protonic conductivity (ca. 10 S cm ). However, the volatility of these heterocycles hampers their application for high-temperature PEMFCs. In order to improve the thermal stability, the immobilization of these heterocyde systems was evaluated [162-164]. When Schuster et al. characterized the conductivity of imidazole-terminated ethylene... 

C. Yuh, P. Patel, R. Kopp, S. Katikaneni and S. Grot, "Novel Composite Membrane-Electrode Assembly for High-Temperature PEMFC," 3rd International Symposium on Proton Conducting Membrane Fuel Cells, The Electrochemical Society Fall Meeting, Salt Fake City, Utah, October 20-24, 2002. 

M. Li, H. Zhang, and Z.-G. Shao. Quatemized poly(phthalazinone ether sulfone ketone) membrane doped with H3PO4 for high-temperature PEMFC operation. Electrochem. Solid-State Lett., 9 A60-A63, 2006. 

Blazquez JA, Pina MP. Novel hybrid membranes based on polybenzimidazole and ETS-10 titanosihcate type material for High Temperature PEMFCs A comprehensive study on dense and porous systems. 7 Power 2011 196(21) 8994-9007. 

The situation is different for HT-PEMFC and LT-PEMFC. The adsorption of carbon monoxide on electro catalyst is driven by the temperature. The CO adsorption is promoted at lower temperatures. A high amount of absorb carbon monoxide on the electro catalysts decreases the performance of the fuel cell dramatically. So low temperature fuel cell requires a hydrogen-rich gas with a very low content of CO in the range of a few ppm. High temperature PEMFC can tolerate a few percent of CO in the hydrogen rich gas and SOFC can use CO directly due to the high operation temperatures. 

The CO content in the hydrogen-rich gas at the outlet of shift reactor is sufficient to operate a high temperature PEMFC. For the operation of a low temperature PEM fuel cell the carbon monoxide content has to reduce further. The content will be reduced in the gas precision cleaning stage to a level that low-temperature PEMFC can tolerate. The gas precision cleaning stage is downstream of the shift reactor and upstream of the PEMFC anode located (see Fig. 6.2). 

Lobato J, Canizares P, Rodrigo MA, Linares JJ, Manjavacas G (2006) Synthesis and characterization of poly[2,2-(m-phenylene)-5,5-bibenzimidazole] as polymer electrolyte membrane for high temperature PEMFCs. J Membr Sci 280 351-362... 

Similar to phosphoric acid, phosphonic acids are intrinsically proton conductive. However, phosphonic acids can he covalently attached to polymers in order to prevent leaching. Comparative studies of sulfonic acid, imidazole, and phosphonic acid functionalized model eompounds have indicated that phosphonie acids possess attractive features for applications in high-temperature PEMFCs. This has spawned extensive research in recent years to prepare and study phosphonated polymers as proton conductors under low humidity eonditions. ... 

Chang et al. [185] prepared SPAE ionomers, xx-PSU-Sn (where xx=mol.% of the sulfonic acid group in the PSF repeating unit= 135,160, and 200. respectively) with three different types of acidic groups (fluoroalkyl sulfonic, aryl sulfonic, and alkyl sulfonic acids), as shown in Scheme 2.52 for low-RH, high-temperature PEMFC applications. 

Lobato, J., Canizares, P., Rodrigo, M., Ubeda, D., and Pinar, F. (2011) A novel titanium PBI-based composite membrane for high temperature PEMFCs.y. Membr. Sci., 369, 105-111. 

Wannek, C., Kohnen, B., Oetjen, H.-F., Lippert, H., and Mergel, J. (2008) Durability of ABPBl-based MEAs for high-temperature PEMFCs at different operating conditions. Fuel Cells, 8 (2), 87-95. 

Lux, K., Elder, W., Bhalerao, A., and Namazian, M. (2008) Distillate-fuel to power systems using high-temperature PEMFCs, in Proceedings of the Fuel Cell Seminar, Palm Springs, CA,... 

Yu S, Xiao L, Benicewicz BC (2008) Durability studies of PBI-based high temperature PEMFCs. Fuel CeUs 8(3 ) 165-174... 

Zhai Y, Zhang H, Liu G, Hu J, Yi B (2006) Performance degradation studies on PBI/H3PO4 high temperature PEMFC and one-dimensional numerical analysis. Electrochim Acta 52(2) 394-401... 

Li QF, Jensen OJ (2008) Membranes for high temperature PEMFC based on acid-doped polybenzimidazoles. Membr Technol 2 61-96... 

Yu S, Benicewicz BC (2009) Synthesis and properties of functionalized polybenzimidazoles for high-temperature PEMFCs. Macromolecules 42(22) 8640-8648... 

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