Chemical fuel cell applications

For the support material of electro-catalysts in PEMFC, Vulcan XC72(Cabot) has been widely used. This carbon black has been successfully employed for the fuel cell applications for its good electric conductivity and high chemical/physical stability. But higher amount of active metals in the electro-catalysts, compared to the general purpose catalysts, make it difficult to control the metal size and the degree of distribution. This is mainly because of the restricted surface area of Vulcan XC72 carbon black. Thus complex and careM processes are necessary to get well dispersed fine active metal particles[4,5]. 

Rodriguez FJ, Sebastian PJ, Solorza O, Perez R (1998) Mo-Ru-W chalcogenide electrodes prepared by chemical synthesis and screen printing for fuel cell applications. Int J Hydrogen Energy 23 1031-1035... 

In the world s largest fuel cell application at a chemical manufacturing site, Dow s by-product hydrogen created as a part of Dow s manufacturing processes, will be converted to electricity by a GM fuel cell. The electricity that is generated will power up the plant. Dow could eventually use up to 35 megawatts of power generated by 500 fuel cell units. 

Kreuer, K. D., Paddison, S. J., Spohr, E. and Schuster, M. 2004. Transport in proton conductors for fuel-cell applications Simulations, elementary reactions, and phenomenology. Chemical Reviews 104 4637-4678. 

Asano, N., Aoki, M., Suzuki, S., Miyatake, K., Uchida, H. and Watanabe, M. 2006. Aliphatic/aromatic polyimide ionomers as a proton conductive membrane for fuel cell applications. Journal of the American Chemical Society 128 1762-1769. 

The current state-of-the-art proton exchange membrane is Nafion, a DuPont product that was developed in the late 1960s primarily as a permselective separator in chlor-alkali electrolyzers. Nation s poly(perfluorosulfonic acid) structure imparts exceptional oxidative and chemical stability, which is also important in fuel cell applications. 

Kivisaari, T. Van der Laag, P. C. Ramskold, A. Benchmarking of chemical flow sheeting software in fuel cell application, Journal of Power Sources, 94, (2001), 112-121. 

Aluminum Batteries Chemical Thermodynamics Electrochemistry Fuel Cells, Applications in Stationary Power Systems Kinetics (Chemistry) Transportation Applications for Fuel Cells... 

For all fuel cells, except those running on high-purity hydrogen, some form of fuel treatment is required. The main problem with fuel supplies intended for conventional combustion systems is the presence of minor contaminants containing ash-making chemicals and sulfur compounds. In fuel cell applications, the sulfur compounds form corrosive substances that poison the catalysts in the reformer stages and the fuel cell itself. 

A major aspect of research and development in industrial catalysis is the identification of catalytic materials and reaction conditions that lead to effective catalytic processes. The need for efficient approaches to facilitate the discovery of new solid catalysts is particularly timely in view of the growing need to expand the applications of catalytic technologies beyond the current chemical and petrochemical industries. For example, new catalysts are needed for environmental applications such as treatment of noxious emissions or for pollution prevention. Improved catalysts are needed for new fuel cell applications. The production of high-value specialty chemicals requires the development of new catalytic materials. Furthermore, new catalysts may be combined with biochemical processes for the production of chemicals from renewable resources. The catalysts required for these new applications may be different from those in current use in the chemical and petrochemical industries. 

In low-temperature fuel cells (AFC, PEMFC, DAFC, etc.), carbon materials are important since they are involved in the fabrication of BP, GDL, and CL. It appears that no other materials can replace carbon with the same properties (good electronic conductivity, good thermal and chemical stabilities, and low cost). But much work is needed to optimize carbon materials for fuel cell applications and to ensure that they meet the performance targets for conductivity, physical properties, and lifetime within operating stacks. 

Monitoring pollutants in a variety of composition ranges in motor vehicle and chemical process exhaust gases is a major area of research in pollution abatement technology. Low-temperature CO oxidation catalysts are needed for zero emission vehicles, CO gas sensors, selective oxidation of CO in H2 rich streams in fuel cell applications,1,2 and in closed-cycle C02 lasers used for remote sensing in space applications.3"5 Effective oxidation of CO during... 

The stability and durability of Pt alloys, especially those involving a >d transition metal, are the major hurdles preventing them from commercial fuel cell applications. "" The transition metals in these alloys are not thermodynamically stable and may leach out in the acidic PEM fuel cell environment. Transition metal atoms at the surface of the alloy particles leach out faster than those under the surface of Pt atom layers." The metal cations of the leaching products can replace the protons of ionomers in the membrane and lead to reduced ionic conductivity, which in turn increases the resistance loss and activation overpotential loss. Gasteiger et al. showed that preleached Pt alloys displayed improved chemical stability and reduced ORR overpotential loss (in the mass transport region), but their long-term stability has not been demonstrated. " These alloys experienced rapid activity loss after a few hundred hours of fuel cell tests, which was attributed to changes in their surface composition and structure." ... 

Perfluorinated membranes are still regarded as the best in the class for PEM fuel cell applications. - These materials are commercially available in various forms from companies such as DuPont, Asahi Glass, Asahi Chemical, 3M, Gore, and Sol-vay. Perfluorosulfonic acid (PFSA) polymers all consist of a perfluorocarbon backbone that has side chains terminated with sulfonated groups. 

PBI (see chemical structure above) is a hydrocarbon membrane that has been commercially available for decades. Free PBI has a very low proton conductivity ( 10 S/cm) and is not suitable for PEM fuel cell applications. However, the proton conductivity can be greatly improved by doping PBI with acids such as phosphoric, sulfuric, nitric, hydrochloric, and perchloric acids. The PA-doped PBI membrane is the most popular one in PEM fuel cell applications because H3PO4 is a nonoxidative acid with very low vapor pressure at elevated temperature. Savinell et al. and Wainright et al. first demonstrated the use of PBI-PA for HT fuel cells in 1994.270 272 since then, there has been a significant amount of research on the PBI-based membrane because of its low cost and good thermal and chemical stabil-... 

Polyarylenes, in particular different types of poly(arylene ether ketone)s, have been the focus of much hydrocarbon membrane research in recent years. - - With good chemical and mechanical stability under PEM fuel cell operating conditions, the wholly aromatic polymers are considered to be the most promising candidates for high-performance PEM fuel cell applications. Many different types of these polymers are readily available and with good process capability. Some of these membranes are commercially available, such as poly(arylene sulfone)s and poly(arylene... 

Polyphosphazene has good chemical and thermal stability. Its polyphosphazene backbone is highly flexible. Various side chains can be introduced to this backbone readily. Cross-linking is needed in order to reduce the dimensional changes in the presence of methanol or water. The membranes have shown reasonable proton conductivity and low methanol crossover. However, an improvement in mechanical strength is needed for practical fuel cell applications. 

Geissler, K., Newson, E., Vogel, E, Truong, T.-B., Hottinger, P., and Wokaun, A. Auto-thermal methanol reforming for hydrogen production in fuel cell applications. Physical Chemistry Chemical Physics, 2001, 3, 289. 

Fatsikostas, A.N., Kondarides, D.I., and Verykios, X.E. Steam reforming of biomass-derived ethanol for the production of hydrogen for fuel cell applications. Chemical Communications, 2001, 851. 

Watanabe, S., Velu, S., Ma, X.L., and Song, C. S. New ceria-based selective adsorbents for removing sulfur from gasoline for fuel cell applications. Preprints of Papers—American Chemical Society, Division of Petroleum Chemistry, 2003, 48, 695. 

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