Solvay cell

The bus bars in the Solvay cells are made primarily of aluminum. Above the cells is a cover that also serves as a convenient walkway, giving access to the anode rods. The titanium anodes are specially coated and are automatically adjusted by computer. The tall vertical decomposers are located under the cells. 

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Mercury is extensively used in various pieces of scientific apparatus, such as thermometers, barometers, high vacuum pumps, mercury lamps, standard cells (for example the Weston cell), and so on. The metal is used as the cathode in the Kellner-Solvay cell (p. 130). 

Sodium hydroxide is manufactured by electrolysis of concentrated aqueous sodium chloride the other product of the electrolysis, chlorine, is equally important and hence separation of anode and cathode products is necessary. This is achieved either by a diaphragm (for example in the Hooker electrolytic cell) or by using a mercury cathode which takes up the sodium formed at the cathode as an amalgam (the Kellner-Solvay cell). The amalgam, after removal from the electrolyte cell, is treated with water to give sodium hydroxide and mercury. The mercury cell is more costly to operate but gives a purer product. 

A second method uses the Kellner-Solvay cell. Saturated sodium chloride solution is electrolyzed between a carbon anode and a flowing mercury cathode. In this case the sodium is produced at the cathode rather than the hydrogen because of the readiness of sodium to dissolve in the mercury. The sodium-mercury amalgam is then exposed to water and a sodium hydroxide solution is produced. 

ELTECH System Corporation currently markets both the Hooker cells and Diamond cells. Other diaphragm-cell technologies developed during the 1970s include the Hooker-Uhde cell and the ICI-Solvay cell. These cell designs are addressed in Chapter 5. 

The second class of metallic solutes is represented by the less electropositive metals. Here, the situation is the reverse of that discussed above. Sodium amalgam is widely used in industry and in the laboratory and is a good example of this class. Upon addition of mercury to liquid sodium, the reactivity of the sodium toward aqueous solutions is vastly reduced, and reaction with hydrogen is slower by an order of magnitude than that for pure sodium. This fact is important in the operation of the Solvay cell for the industrial production of sodium hydroxide by electrolysis of brine, in which sodium amalgam forms one of the electrodes. In such amalgams, valency electrons from the conduction band of liquid sodium, which would normally be responsible for its chemical reactivity, are partially localized on the mercury atoms, thus inhibiting the reactivity of sodium. 

In Europe, there are several programs under the support of the European Commission. The goal of the Joule III NEMECEL Program (which involves four industrial companies—Thomson CSF and PSA in France, De Nora in Italy, Solvay in Belgium, one CNR laboratory in Italy and two Centre National de la Recherche Scientifique (CNRS) laboratories in France, including our laboratory) is to develop a stack with a power level of 200 mW/cm at a cell potential of 0.5 to 0.6 V and a total power... 

A thiazole core has also been utilised by Solvay Pharmaceuticals [309] in the search for a novel bioisosterie replacement of the rimonabant (382) pyrazole core. The affinity of several compounds for the human CBi receptor was determined in transfected CHO cells using tritium-labelled CP 55940. Antagonism was determined in the same cell line by WIN 55212-2-induced release of arachidonic acid. The pK[ of (456) was found to be 6.9, while the p 2 value was measured as 8.7. A series of six 1,2,4-triazole analogues has been prepared by Jagerovic et al. [310], via their corresponding A-acylbenzamides (Table 6.39). 

Figure 1.17 Cell voltage and power density vs current density curves for (a) 2 M methanol in 4 M NaOH solution (b) 2 M ethylene glycol in 4 M NaOH solution. Anode and cathode catalysts, laboratory-made Pt (40wt%)/C prepared via the Bdnnemann method, 2mgPtcm commercial anionic membrane, Morgane ADP from Solvay T=20°C.

Early demand for clilorine centered on textile bleaching, and clilorine generated through the electrolytic decomposition of salt (NaQ) sufficed. Sodium hydroxide was produced by the lime —soda reaction, using sodium carbonate readily available from the Solvay process. Increased demand for clilorine for PVC manufacture led to the production of clilorine and sodium hydroxide as coproducts. Solution mining of salt and the availability of asbestos resulted in the dominance of the diaphragm process in North America, whereas solid salt and mercury availability led to the dominance of the mercury process in Europe. Japan imported its salt in solid form and, until the development of the membrane process, also favored the mercury cell for production. 

Nafion, a perfluorinated sulfonic acid (PFSA) polymer electrolyte developed and produced by the E. I. Dupont Company, has been extensively studied as a fuel cell membrane. Despite its age, it remains the industry standard membrane because of its relatively high proton conductivity, toughness and quick start capabilities. Attempts to build upon the strengths of Nafion have resulted in a class of PFSA polymer electrolytes, including the short-side-chain (SSC) PFSA polymer electrolyte, originally synthesized by Dow and now produced by Solvay Solexis. Stracturally, PFSA polymer... 

Investigations on Dow membranes can be found in Refs. [70-82]. Solvay Solexis has started a research and development project to create new ionomer membranes for fuel cells and other applications similar to the Dow concept. The development is based on Solexis s capability for producing sulfonylfluoridevinylether by a much simpler route than the original Dow synthesis [83]. The Solexis route is schematically represented in Figure 27.29 and the monomer can be produced on an industrial scale. The SSC monomer and TFE are copolymerized by free-radical polymerization to obtain the polymers in Figure 27.30 (named Hyflon Ion). 

The structure factor F hkl) is the Fourier transform of the unit cell contents sampled at reciprocal lattice points, hkl. The structure factor amplitude (magnitude) F is the ratio of the amplitude of the radiation scattered in a particular direction by the contents of one unit cell to that scattered by a single electron at the origin of the unit cell under the same conditions (see Chapter 3). The first report of the structure factor expression was given by Arnold Sommerfeld at a Solvay Conference. The structure factor F has both a magnitude F(hkl) and a phase rel-... 

An additional source of sodium carbonate occasionally used is via the carbonation of electrolytic sodium hydroxide as it is formed in the cell, or separately, later (e.g., [26]). The precipitated sodium hydrogen carbonate is calcined to obtain sodium carbonate in a maimer similar to the last step of the Solvay process (Eq. 7.15). 

The main mercury cathode electrolytic cells used in the industry were developed chiefly by De Nora and Uhde, and to a lesser extent by IC1, Krebs Kureha, Olin and Solvay. 

Ion-exchange membranes based on radiation grafting technology are produced by Solvay. Different fluorinated polymers explored for fuel-cell membranes have been reviewed by Kostova et al. [164]. 

Morgane ADP membrane, a cross-linked fluorinated polymer with quaternary ammoiuum exchange groups, from Solvay has been used in fuel cells fed with methanol, glycerol and ethylene glycol [228, 258-264]. Finally, Fumasep FAA, a commercial quatemized polysulfone membrane by Fumatech, was employed in DMFC [265] and DEFC [266]. A recent review by Yu et al. [267] summarizes the performance of DAFC using commercial and non-commercial AEM. 

The polymer material used for the artificial cornea was Solef 1008/0001 and for the cell tests 1006/0001 produced by Solvay-Solexis S.A., Tavaux, France. The melt spinning trials were performed at a bicomponent plant (Foumd Polymertechnik GbmH, Alfter-Impekoven, Germany, Figure 1). 

Special thanks shall be e qiressed to the Stiftung Industriefoischmig (Research foundation of the German industry) which founds the scholarship of the project Development of new fibre structures for improvement of cell adhesion fi>r medical textOes . Furtha- to Petra R5sdi at the PC for assistance in Raman spectroscopy and finally to Stefiuio Mortara and Mattia Bassi at Solvay Solexis for WAXD analysis. 

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