Nafion divided cell

Application of a divided cell containing one pair of electrodes (Pt-coated Ti anode 316 type stainless steel cathode) with an effective area of 100 cm2. Nafion-324 was used as the membrane. Two 81 tanks contained anolyte (feed) and catholyte (caustic). A coil-type heat exchanger was used to maintain the heat... 

For the continuous process, a special divided cell (Pb02/steel anode, steel cathode, Nafion as cation exchange membrane) based on the principle of a tubular reactor was developed. The final product can be removed in gaseous form, so that the electrolyte can be recycled in a simple manner. The membrane and electrodes are supposed to have lifetimes of at least one year 63). Hexafluoropropylene is a useful monomer for fluorine-containing polymers, e.g., fluorinated polyethers. 

Divided cells — Electrochemical cells divided by sintered glass, ceramics, or ion-exchange membrane (e.g., - Nafion) into two or three compartments. The semipermeable separators should avoid mixing of anolyte and - catholyte and/or to isolate the reference electrode from the studied solution, but simultaneously maintain the cell resistance as low as possible. The two- or three-compartment cells are typically used a) for preparative electrolytic experiments to prevent mixing of products and intermediates of anodic and cathodic reactions, respectively b) for experiments where different composition of the solution should be used for anodic and cathodic compartment c) when a component of the reference electrode (e.g., water, halide ions etc.) may interfere with the studied compounds or with the electrode. For very sensitive systems additional bridge compartments can be added. 

The cell shown in Figure 1 (also called an H-cell because of its shape) is a divided cell, wherein a porous glass frit or polymer e.g. Nafion) prevents the anolyte and catholyte solutions from mixing with each other. In some cases, however, a simple beaker can be used (undivided cell). 

Platinum chemically deposited on a Nafion membrane was used as a platinum SPE (Solid Polymer Electrolyte) electrode. The electrochemical measurements were performed using the half cell shown in Fig. 2-2. The cell body is made from Teflon (PTFE). The cell is divided into two compartments one for backside gas supply one for the electrolyte. SPE electrodes are placed between them with the deposited side facing the gas compartment. A gold foil with a hole was placed behind the SPE electrode... 

Divided parallel plate flow-through cells are especially advantageous for laboratory use because they can easily be constructed from two Teflon cell body halves according to Figure 22.14. In such a construction, ion-exchange membranes can easily be applied for the separation of the two cell compartments. For anodic oxidations, cation exchange membranes like Nafion are most often used. For cathodic reactions, anion exchange membranes are applicable. Asbestos or microporous membranes can also be used as separators. 

As described before in this chapter, conventional DEFCs can be divided into two types as a function of fhe employed membrane, namely proton exchange membrane DEFCs (PEM-DEFCs) and anion exchange membrane DEFCs (AEM-DEFCs), used in acidic and alkaline medium, respectively. As previously reported, Pt-based catalysts undergo rapid poisoning of the catalytic sites, which compromises cell performance. On the other hand, the kinetics of both ethanol oxidation (OER) and the oxygen reduction reaction (ORR) in alkaline medium are much faster than the corresponding kinetics in acidic medium, which substantially improves cell performance. The main limitation to the cell performance in AEM-DEFCs is the physical and chemical stability of the AEM [71]. Another problem encountered with the AEM is that its ionic conductivity is about one order of magnitude lower than that of Nafion membranes. 

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