Perfluorosulfonic acid polymer membranes

The principle of operation is shown in Fig. 2. Chlorine gas is produced at the anode (especially optimized dimensionally stable anode) with an anolyte feed concentration of 14 wt % HCl. Anode and cathode are separated by a cation exchange membrane (perfluorosulfonic acid polymer, PFSA, e.g., Nafion of DuPont). The ODC is based on a conductive carbon cloth which operates simultaneously as a gas diffusion layer because a suitable material is incorporated. The oxygen reduction reaction (5) takes place in three-phase boundaries of a thin, porous catalyst layer on the surface. 

The PEM (proton exchange membrane) material is a perfluorosulfonic acid polymer film. Several manufacturers make PEMs in one form or another. We used one made by du Pont called Nation 117. Nation 117 is a transparent polymer film about 175 microns (0.007 inches) thick. Dow Chemical Co., Asahi Chemical Co., and Chloride Engineers Ltd. make something similar. A patent describing how one PEM manufacturer s film is processed is listed in the references section at the end of this article. 

Perfluorosulfonic acid polymers, for example, Nafion, or ionic and cross-linked polystyrene derivatives, are the best known examples of ion-exchange membrane materials (see also Section 2.6.4). 

Solid Polymer Electrolyte Fuel Cell Here, there is no apparent liquid solution, or high-temperature ionic conductor. The usual ionic solution between the electrodes is replaced by a well-humidified membrane made of a perfluorosulfonic acid polymer that conducts protons. 

Y. Chang, G.F. Brunello, J. Puller, M.L. Disabb-Miller, M.E. Hawley, Y.S. Kim, M.A. Hickner, S.S. Jang, C. Bae, Polymer electrolyte membranes based on poly(arylene ether sulfone) with pendant perfluorosulfonic acid, Polym. Chem. 4 (2) (2013) 272-281. 

Product Information, 2005, DuPont Nafion PFSA Membranes N-112, NE-1135, N-115, N-117, NE-1110 Perfluorosulfonic Acid Polymer. NAEIOI. 

The diaphragm may be replaced by a cation exchange membrane which is suitable for high concentrated hydrochloric acid like Nafion (DuPont, perfluorosulfonic acid polymer, PFSA, see entry Chlorine and Caustic Technology, Membrane Cell Process ). This membrane has almost no usual porosity and is nearly exclusively permeable for ions including a hydration shell of some water molecules. Thus, product quality is significantly increased, process operation can be simplified, and cell voltage is reduced by about 0.3 V [1, 6]. However, the mechanical durability... 

DuPont Fluoroproducts have more than 30 years of fuel cell development experience. The company dispersion-casts or extrudes its Nafion brand of perfluorosulfonic acid polymer/PTFE copolymer membranes. 

Siracusano S, Baglio V, Stassi A et al (2014) Performance analysis of short-side-chain Aquivion perfluorosulfonic acid polymer for proton exchange membrane water electrolysis. J Membr Sci 466 1-7... 

Choi J, Lee KM, Wycisk R, Pintauro PN, Mather PT (2010) Nanofiber composite membranes with low equivalent weight perfluorosulfonic acid polymers . J. Mater. Chem. 20 6282. 

Biocompatibility of Perfluorosulfonic Acid Polymer Membranes for Biosensor Applications... 

So, the particles have at least one dimension that is less than 200 nm. The use of nanoparticles was found to improve the performance of the membrane assemblies compared to assemblies using macroparticles. As ionomers, perfluorosulfonic acid polymers, e.g., poly-(tetrafluoroethylene-perfluorosulfonyl fluoride), can be used (153). 

Abstract There have been numerous studies on modifying DuPont s Nafion (a perfluorosulfonic acid polymer) in order to improve the performance of this membrane material in a direct methanol fuel cell. Modifications focused on making Nafion a better methanol barrier, without sacrificing proton conductivity, so that methanol crossover during fuel cell operation is minimized. In this chapter, a brief literature survey of such modifications is presented, along with recent experimental results (membrane properties and fuel cell performance curves) for (1) thick Nafion films, (2) Nafion blended with Teflon-FEP or Teflon-PFA, and (3) Nafion doped with polybenzimidazole. 

Chang Y, Brunello GF, Fuller J, et al. Polymer electrolyte membranes based on poly(arylene ether sulfone) with pendant perfluorosulfonic acid. Polym Chem. 2013 4 272-281. 

Fig. 7 Chemical structure of the perfluorosulfonic acid polymer used in Nafion membranes...

Polymer electrolyte membrane or proton exchange membrane fuel cells (PEMFC) use a thin (s50 im) proton conductive polymer membrane (such as perfluorosulfonated acid polymer) as the electrolyte. The catalyst is typically platinum supported on carbon with loadings of about 0.3mg/cm, or, if the hydrogen feed contains minute amounts of CO, Pt-Ru alloys are used. Operating temperature is typically between 60 and 80°C. PEM fuel cells are a serious candidate for automotive applications, but also for small-scale distributed stationary power generation, and for portable power applications as well. 

The electrolyte is a perfluorosulfonic acid ionomer, commercially available under the trade name of Nafion . It is in the form of a membrane about 0.17 mm (0.007 in) thick, and the electrodes are bonded directly onto the surface. The electrodes contain very finely divided platinum or platinum alloys supported on carbon powder or fibers. The bipolar plates are made of graphite-filled polymer or metal. 

Futerko and Hsing presented a thermodynamic model for water vapor uptake in perfluorosulfonic acid membranes.The following expression was used for the membrane—internal water activity, a, which was borrowed from the standard Flory—Huggins theory of concentrated polymer solutions ... 

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