Perfluorosulfonic acid composite

High Temperature Operation of the PEMFC The first generation of commercial PEMFCs will use presently known components, consisting of a perfluorosulfonic acid membrane as electrolyte and catalyst compositions as cited above. The electrolyte determines that the fuel cell needs to be operated at fully humidified conditions and limits the operating temperature to 80-90 °C. 

Adjemian, K. T., Srinivasan, S., Benzieger, J. and Bocarsly, A. B. 2002. Investigation of PEMFC operation above 100°C employing perfluorosulfonic acid silicon oxide composite membranes. Journal of Power Sources 109 356-364. 

Bronsted acids can also be fixed to the surfaces of many common support materials. Surface attached perfluorosulfonic acids have been reported123 as well as the perfiuorinated sulfonic acid resin (Nafion)-silica composites reported a year earlier.124 The former are prepared by reacting... 

Numerous polymers have been studied for their potential apphcation in PEMFCs. Based on their chemical structure, these polymers can be categorized into (a) vinylic polymers, (b) aromatic polymers, and (c) polymer blends and composite/hybrid polymers. Generally, vinylic polymers are synthesized by addition polymerization, while aromatic polymers are synthesized by step-growth polymerization. The most studied vinylic polymers for PEMFC applications are perfluorosulfonic acid ionomers (PFSls), in particular Nation , and styrene sulfonic acid-based polymers. Chemical structures of representative vinyhc PEMs are shown in Scheme 2. 

Solid state NMR measurements were applied to characterize polyethylene/ clay composite materials. The solid-state NMR measurements were used to observe both polymer matrix ( C and H) and the clay ( Si and A1). Free volume of poly(perfluorosulfonic acid)/Si02 composites were studied by Xe NMR. The free volume is heterogeneous and depends on the... 

These composite membranes are prepared either by lamination of the perfluoro-carboxylate and perfluorosulfonate films [75-77] or by the chemical conversion [78-80] of one surface of the perfluorosulfonic acid to perfluorocarboxylic acid to realize a carboxylate layer thickness of 5-10 xm. 

Ma, Xu, Liu, and Sun (2010) used perfluorosulfonic acid-poly(vinyl alcohol)-Si02/ poly(vinyl alcohol)/polyacrylonitrile (PFSA-PVA-Si02/PVA/PAN) bifunctional hollow-fiber composite membranes. The catalytic and the selective layer of the membrane were independently optimized. These membranes were synthesized by dipcoating. The performance of these bifunctional membranes was evaluated by dehydrating the ternary azeotropic composed of a water, ethanol, and ethyl acetate system (top product of a reactive distillation process of esterification of acetic acid with ethanol), obtaining separation factors of water/ethanol up to 379. An extensive assessment on the esterification reaction of ethanol-acetic acid was later published (Lu, Xu, Ma, Cao, 2013). In this case, the reaction equilibrium was broken in less than 5 h, and a 90% conversion of acetic acid was achieved after 55 h. 

C. Fihpoi, D.E. Demco, X. Zhu, R. Vinokur, O. Conradi, R. Fechete, M. Moeller, Channel orientation anisotropy in perfluorosulfonic acid/Si02 composite proton exchange membranes water selfrdiffiision study using NMR, Chem. Phys. Lett. 513 (2011) 251-255. 

As mentioned above, perfluorosulfonic acid (PFSA) membranes like Nation (Dupont) are CEMs of very high chemical and thermal stability. In a highly sophisticated composition, such membranes are used as separators in industrial chlor-alkali electrolysis. Most research in the area of SPE electrosynthesis has also been done using Nation membranes. 

Zhang YM, Li L, Tang J, Bauer B, Zhang W, Gao HR, Taillades-Jacquin M, Jones DJ, Roziere J, Lebedeva N, Mallant R (2009) Development of covalently cross-linked and composite perfluorosulfonic acid membranes. ECS Trans 25 1469-1472... 

Membrane. Perfluorosulfonic acid (PFSA) is the most commonly used membrane material [4], PFSA membranes are relatively strong and stable in both oxidative and reductive environments, since the structure of PFSA is based on a PTFE backbone. The conductivity of a well-humidified PFSA membrane can be as high as 0.2s cm. As is well known, fuel cell operation at elevated temperatures can increase the rates of reaction, reduce problems related to catalyst poisoning, reduce the use of expensive catalysts, and minimize problems due to electrode flooding. Unfortunately, a PFSA membrane must be kept hydrated to retain its proton conductivity. Moreover, a PFSA membrane is alcohol permeable if it is used in DAFCs. Because of the disadvantages of PFSA membranes, many alternatives have been proposed [106]. Five categories of membranes are classified (1) perfluorinated, (2) partially fluorinated, (3) non-fluorinated, (4) non-fluorinated composite, and (5) others. 

Composite Perfluorosulfonic Acid Membranes for Direct Methanol Fuel Cells... 

It appears that the performance of composite perfluorosulfonic acid (PFSA) membrane-based MEAs is generally better than the corresponding hydrocarbon counterpart. This is due to the effect of higher conductivity and better interface with the electrodes. 

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. 

Choi J, ciskR, Zhang W, Pintauro PN, Lee KM, Mather PT (2010) High conductivity perfluorosulfonic acid nanofiber composite fuel cell membranes . ChemSusChem 3 1245. 

Field responsivity of a polyelectrolyte-metal composite membrane made of a perfluorosulfonic acid to which platinum is electroplated on both sides is being evaluated [44]. If a voltage is applied using the platinum layer as the electrode after the composite membrane is immersed... 

Abstract In this chapter, we discuss the proton conductivity and use of heteropoly acids (HP As) in proton exchange fuel cells. We first review the fundamental aspects of proton conduction in the HPAs and then review liquid HPA-based fuel cells. Four types of composite proton exchange membranes containing HPAs have been identified HPAs imbibed perfluorosulfonic acid membranes, HPAs imbibed hydrocarbon membranes, sol-gel-based membranes, and polymer hybrid polyoxometa-late (polypom)-based membranes. 

Perfluorosulfonic acid prepared in laboratory Polyethersulfone loaded with CaCOs The composite membranes had highly increased break strength and Young s modulus [81]... 

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