Hydrocarbon composite membranes membrane fuel cells

Polymer Membranes in Fuel Cells takes an in-depth look at the new chemistries and membrane technologies that have been developed over the years to address the concerns associated with the materials currently in use. Unlike the PFSAs, which were originally developed for the chlor-alkali industty, the more recent hydrocarbon and composite materials have been developed to meet the specific requirements of PEM Fuel Cells. Having said this, most of the work has been based on derivatives of known polymers, such as poly(ether-ether ketones), to ensure that the critical requirement of low cost is met. More aggressive operational requirements have also spurred the development on new materials for example, the need for operation at higher temperature under low relative humidity has spawned the creation of a plethora of new polymers with potential application in PEM Euel Cells. 

Hydrocarbon Polymer Electrolytes for Fuel Cell Application (J. Qiao and T. Okada, 2008, Nova Science Publishers) focuses on composite membranes for direct methanol fuel cells. 

In recent years, many kinds of materials have been developed to synthesize proton-conducting membranes for H2/air PEM fuel cells, and some have exhibited promising performance as potential candidates to replace PFSA membranes. The major membranes are (1) fluorinated membrane, (2) partially fluorinated membrane, (3) nonfluorinated (including hydrocarbon) membrane, and (4) nonfluorinated composite membrane. Among these, the hydrocarbon membrane is considered a promising alternative due to its low cost compared with PFSA membranes [61]. 

Chapters 6 and 7 deal with the hydrocarbon polymers and composites targeted for high temperature PEM fuel cell applications. Specifically, chapter 6 deals with a series of high molecular weight, highly sulfonated poly(arylenethioethersulfone) (SPTES) polymers synthesized by polycondensation. They were characterized by different methods and tested for proton conductivity. Finally, membrane electrode assemblies (MFAs) were fabricated. 

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. 

Novel Processing Schemes Various separators have been proposed to separate the hydrogen-rich fuel in the reformate for cell use or to remove harmful species. At present, the separators are expensive, brittle, require large pressure differential, and are attacked by some hydrocarbons. There is a need to develop thinner, lower pressure drop, low cost membranes that can withstand separation from their support structure under changing thermal loads. Plasma reactors offer independence of reaction chemistry and optimum operating conditions that can be maintained over a wide range of feed rates and H2 composition. These processors have no catalyst and are compact. However, they are preliminary and have only been tested at a laboratory scale. 

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