Preparation of Cation Exchange Membranes

In preparing cation exchange membranes having carboxylic acid groups, acrylic acid, methacrylic acid and their esters, etc., are copolymerized with divinylbenzene and, optionally, other vinyl monomers. The copolymer membranes are then immersed in hydroxide solution, or the ester groups of the membranes are hydrolyzed. 

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In recent years, many papers have reported the preparation of cation exchange membranes by this method to obtain solid polymer electrolytes for fuel cells. 

M. Seko, Y. Yamagoshi, K. Miyauchi, M. Fukumoto, I. Watanabe, K. Kimoto, T. Hane and S. Tsushima, Membrane composite for preparation of cation exchange membrane, Jpn. Pat. JP 56-37247 (examined application) Cation exchange membrane, Jpn. Pat. JP 56-18605 (examined application) Preparation method of fluorocarbon cation exchange membrane, Jpn. Pat. JP 56-3 7248 (examined application). 

Zu, J., Zhang, J., Sun, G., Zhou, R. and Liu, Z. 2009. Preparation of cation-exchange membrane containing bi-functional groups by radiation induced grafting of acrylic acid and sodium styrene sulfonate onto HDPE Influence of the synthesis conditions,... 

M.M. Nasef, H. Saidi and H.M. Nor, Radiation-induced graft copolymerization for preparation of cation exchange membranes A review, Nucl. Sci. J. Malaysia 17, 27 (1999). 

Hwang, G., Ohya, H., Nagai, T. (1999) Ion exchange membrane based on block copolymers. Part III. Preparation of cation exchange membrane. Journal of Membrane Science, 156, 61-65. 

Figure 3.5 Effect of membrane composition on electrical conductivity and transport number of cation exchange membrane prepared by the paste method. (O, O) transport number ( , ) specific conductivity. DVB divinylbenzene St styrene PVC poly(vinyl chloride). Composition DVB/(St + DVB) — 0.1 (by weight) numbers in the figure are DOP/PVC (DOP dioctyl phthalate -additives) (by weight). The copolymer membrane is sulfonated with concentrated sulfuric acid.

T. Kuwata and S. Yoshikawa, Preparation method of cation exchange membrane, Jpn. Pat. JP 32-4590 (examined application). 

T. Kuwata and S. Yoshikawa, Preparation method of cation exchange membranes. Jpn. Pat. JP 40-531 (examined application), 1965 M. Kato, K. Akiyama and M. Yamabe, New perfluorocarbon polymers with phosphoric groups, Rep. Res. Lab. Asahi Glass Co Ltd., 1983, 33, 135-142. 

T. Sata, T. Funakoshi and K. Akai, Preparation of transport properties of composite membranes composed of cation exchange membranes and polypyrrole, Macromolecules, 1996, 29, 4029-4035. 

R. Ehara, T. Misumi and T. Miwa, Preparation methods of cation exchange membranes having preferential permselectivity to lower valence cation, Jpn. Pat., JP 49-3917 (examined application). 

A much more elegant way to prepare hydroxide eluents has been introduced by Liu et al. [196]. The respective device was commercialized under the trade name Eluent Generator . The most important part of this module is a cartridge, in which potassium hydroxide is generated by means of electrolysis. As schematically depicted in Figure 3.200, such a cartridge consists of an electrolyte reservoir, which is filled with a concentrated KOH solution and connected to an electrolysis chamber via a stack of cation-exchange membranes. While the... 

In Chapter 18, Matsuyama and Teramoto report the preparation of new types of cation-exchange membranes by grafting acrylic acid and methacrylic acid to substrates, such as microporous polyethylene, polytetrafluoroethylene, and poly[l-(trimethylsilyl)-l-propyne], by use of a plasma graft polymerization technique. Various monoprotonated amines are immobilized by electrostatic forces in the ion-exchange membranes and used as carriers for carbon dioxide. With these membrane systems carbon dioxide/nitrogen selectivities of greater than 4700 are obtained with high carbon dioxide flux. 

The electrochemical properties of cation-exchange membranes based on sulfonated poly(arylene ether sulfone)s (s-PES) were described in a paper by Kang et al. [100]. The intended applications for these membranes were general electro-membrane rather than fuel cell applications. The properties of the membranes prepared in this work were compared to commercially available ion-exchange membranes (Neosepta CM-1, CMX, and CMB), as well as to sulfonated polysulfones obtained by post-sulfonation of Udel 1700 with chlorosulfonic acid (s-PSU) (Fig. 26). The s-PES membrane materials were... 

Shah NT, Goodwin J C and Ritchie SMC (2005), Preparation and electrochemical characterizations of cation-exchange membranes with different functional groups , / Membr Sci, 251,81-89. 

Assink, R. A., Arnold, C. J. and Hollandsworth, R. P. 1991. Preparation of oxidatively stable cation-exchange membranes by the elimination of tertiary hydrogens. Journal of Membrane Science 56 143-151. 

A method of preparing both cation- and anion-exchange membranes, which is used for the preparation of commercial cation-exchange membranes, is the poly-... 

One of the technically and commercially most important cation-exchange membranes developed in recent years is based on perfluorocarbon polymers. Membranes of this type have extreme chemical and thermal stability and they are the key component in the chlorine-alkaline electrolysis as well as in most of today s fuel cells. They are prepared by copolymerization of tetrafluoroethylene with perfluorovinylether having a carboxylic or sulfonic acid group at the end of a side chain. There are several variations of a general basic structure commercially available today [11]. The various preparation techniques are described in detail in the patent literature. 

More recently cation-exchange membranes with good mechanical and chemical stability and well-controlled ion-exchange capacity are prepared by dissolving and casting a functionalized polymer such as sulfonated polysulfone, or sulfonated polyetheretherketone in an appropriate solvent, followed by casting the mixture into a film and then evaporation of the solvent [12]. 

Double decomposition is similar in concept to the substitution reaction, except that both anion-exchange and cation-exchange membranes are employed. Simultaneous interchange of anion-cation pairing takes place to form products that would otherwise require multistep procedures to prepare and purify. Pure materials can be produced from crude raw materials by means of double decomposition, and reactions otherwise impractical by conventional reaction methods can be performed. An example application is the reaction between potassium chloride and sodium nitrate to produce potassium nitrate and sodium chloride. 

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