Hybrid membranes applications

Sol-gel techniques have been widely used to prepare ceramic or glass materials with controlled microstructures. Applications of the sol-gel method in fabrication of high-temperature fuel cells are steadily reported. Modification of electrodes, electrolytes or electrolyte/electrode interface of the fuel cell has been also performed to produce components with improved microstructures. Recently, the sol-gel method has expanded into inorganic-organic hybrid membranes for low-temperature fuel cells. This paper presents an overview concerning current applications of sol-gel techniques in fabrication of fuel cell components. 

Controlled formation of three-dimensional functional devices in silica makes the hybrid membrane materials presented here of interest for the development of a new supramolecular approach to nanoscience and nanotechnology through self-organization, towards systems of increasing behavioral and functional addressabilities (catalysis, optical and electronic applications, etc.). 

D.R. Vernon, F. Meng, S.F. Dee, D.L Williamson, J.A. Turner, and A.M. Flerring, Synthesis, Characterization, and Conductivity Measurements of Hybrid Membranes Containing a Mono-lacunary Heteropolyacid for PEM Fuel Cell Applications,/. Power Sources, 139, 141-51 (2005). 

Miyake, N., Wainright, J. S. and Savinell, R. E 2001. Evaluation of a sol-gel derived Nafion/silica hybrid membrane for proton electrolyte membrane fuel cell applications. I. Proton conductivity and water content. Journal of the Electrochemical Society 148 A898-A904. 

On the other hand, a pervaporation membrane can be coupled with a conventional distillation column, resulting in a hybrid membrane/distillation process (228,229). Some of the investigated applications of such hybrid pervaporation membrane/distillation systems are shown in Table 9. In hybrid pervaporation/ distillation systems, the membrane units can be installed on the overhead vapor of the distillation column, as shown in Figure 13a for the case of propylene/ propane splitting (234), or they can be installed on the feed to the distillation column,... 

Besides previously described examples of integrated membrane systems and much more reported in the literature, including applications in gas separation and the petrochemical industry [29], a special case of integrated or hybrid membrane systems, with a lot of interest in the logic of the sustainable growth, is represented by the catalytic membranes reactors (CMRs). 

The OHLM systems, integrating reaction, separation, and concentration functions in one equipment (bioreactor), find a great interest of researchers in the last few years. A bioreactor combines the use of specific biocatalyst for the desired chemical reactions, and repeatedly or continuously application of it under very specific conditions. Such techniques were termed as hybrid membrane reactors. In biotechnology and pharmacology, these applications are termed as hybrid membrane bioreactors or simply bioreactors (see Table 13.11). Experimental setup of the bioreactor system is shown schematically in Figure 13.17. 

N. Miyake, J.S. Wainright and R.F. Savinell, Evaluation of a sol-gel derived Nafion/ silica hybrid membrane for polymer electrolyte membrane fuel cell applications. II. Methanol uptake and methanol permeability, J. Electrochem. Soc., 2001, 148, A905-A909. 

Arthanareeswaran, G. and Thanikaivelan, P. 2010. Fabrication of cellulose acetate-zirconia hybrid membranes for ultrafiltration applications Performance, structure and fouling analysis. Separation and Purification Technology lA 230-235. 

Esteves A., Mota J. P. B. 2011. Novel hybrid membrane/pres-sure swing adsorption processes for gas separation applications. In Drioli E. and Barbieri G. (eds.) Membrane Engineering for the Treatment of Gases, pp. 245-275. Cambridge, U.K. The Royal Society of Chemistry. ISBN 978-1-84973-239-0. 

Wu et al. [106] prepared hybrid direct methanol fuel cell membranes by embedding organophosphorylated titania submicrospheres (OPTi) into a CS polymer matrix. The pristine monodispersed titania submicrospheres of controllable particle size are synthesized through a modified sol-gel method and then phosphorylated by amino trimethylene phosphonic acid (ATMP) via chemical adsorption. Compared to pure CS membrane, the hybrid membranes exhibit increased proton conductivity to an acceptable level of 0.01 S/cm for DMFC application and a reduced methanol permeability of 5 xlO cm /s at a 2 M methanol feed. 

As compared to mesoporous oxide nanofibers, much lesser attention has been paid to their mesoporous amorphous carbon analogues. However, mesoporous carbon exhibits superior resistance to acids and bases, excellent heat resistance, as well as high intrinsic electric conductivity. Potential applications for hybrid membranes consisting of mesoporous carbon within hard templates include size-selective electrosorption, electrosynthesis of nanostructures, catalysis, separation and storage. The first reported procedure for the synthesis of mesoporous carbon nanofibers involved the preparation of... 

Hybrid Membrane Systems -Applications and Case Studies... 

The hybrid systems described below include membrane technologies for processing a wide spectrum of feed streams in various applications. A small sampling of current and potential applications is discussed. The list of examples selected is intentionally Hmited the intention is to illustrate the extent of process alternatives possible with various hybrid membrane processes. 

Hybrid membrane systems - applications and case studies... 

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