Chlor-alkali technology membranes

DuPont s perspective on membrane development will be outlined. The expansion of the facilities at the Nafion Customer Service Laboratory will also be described. This expansion has been undertaken in support of DuPont s commitment to increase the understanding of chlor-alkali technology and ensure continuous improvement of DuPont s membranes. 

In its support of the commitment to increase the understanding of chlor-alkali technology and to continuously improve its membranes, DuPont has expanded its CSL (Customer Service Laboratory) facilities at Fayetteville, North Carolina in the United States. 

Iacopetti, L. (1998) Membrane electrolyser operating at high current density. In Modern Chlor-Alkali Technology, Vol. 7 (ed. S. Sealey), pp. 85-94. Society of Chemical Industry, London and Royal Society of Chemistry, Cambridge. 

Sajima, Y., Nakao, M., Shimohira, T. Miyake, H. (1992) Advances in flemion membranes for chlor-alkali production. In Modern Chlor-alkali Technology (ed. T.C. Wellington), Vol. 5, pp. 159-175. Hays Chemical Distribution Ltd., Sandbach, UK. 

Membrane cells are the state of the art chlor-alkali technology as of this writing. There are about 14 different membrane cell designs in use worldwide (34). The operating characteristics of some membrane cells are given in Table 3. The membranes are perfluorosulfonate polymers, perfluorocarboxylate polymers, and combinations of these polymers. Membranes are usually reinforced with a Teflon fabric. Many improvements have been made in membrane cell designs to accommodate membranes in recent years (35,36). 

Equilibration with water vapor Substantially less work was done in this area in the early phase of research on PFSAs because of previous emphasis on membranes which would be in contact with liquid water or aqueous solutions (e.g., for chlor-alkali technology). However, water supplied from the vapor phase could be a principal mode of external hydration of the membrane in a PEFC, particularly hydration of the anode side, and thus it is an important focus of study in fuel cell R D. The shape of the sorption isotherms shown in Fig. 29 (a) and (b) is generic for ion-exchange polymers. With increasing PhsO. water is sorbed in two steps as evidenced by the sorption isotherm ... 

In April 1975, Asahi Chemical started operation of a membrane chlor-alkali plant with a capacity of 40,000 MT/Y of caustic soda using Nafion perfluorosulfonic acid membrane. In 1976, this membrane was replaced by perfluorocarboxylic acid membrane developed by Asahi Chemical. The total caustic production capacity of plants based on Asahi Chemical s membrane chlor-alkali technology using perfluorocarboxylic acid membrane will reach 520,000 MT/Y in 1982, at seven locations in various countries. 

Yomiyama, A., Energy reduction in a membrane chlor-alkali process (in Japanese), presented at 4th Meeting on Industrial Chlor-alkali Technology of the Electrochem. 

G.W. Cowell, A.D. Martin, and B.K. Revill, A New Improved Method for the Determination of Sodium Hydroxide Efficiency in Membrane Cells. In T.C. Wellington (ed.). Modem Chlor-Alkali Technology, vol. 5, Elsevier Applied Science, New York (1992), p. 143. 

D. Bergner, M. Hartmann, and H. Kirsch, Voltage-Current Curves Application to Membrane Cells. In N.M. Prout and J.S. Moorhouse (eds). Modem Chlor-Alkali Technology, vol. 4, Elsevier Applied Science, London (1900), p. 158. 

W.G. Grot, Discovery and Development of Nafion Perfluorinated Membranes The SCI. Castner Medal Lecture. In K. Wall (ed.). Modem Chlor-Alkali Technology, Ellis Horwood Ltd, Chichester, Vol. 3, (1986), p. 122. 

H. Obanawa, H. Naoki, H. Takei, and H. Hoda, Simulation of Ion Behavior in Ion Exchange Membranes. In S. Sealy (ed.) Modem Chlor-Alkali Technology, Vol. 7, Royal Society of Chemistry, Cambridge (1998), p. 113. 

T. Shimohira, T. Kimura, T. Uchibori, and H. Takeda, Advanced Cell Technology with Flemion Membranes and the AZEC Bipolar Electrolyzer. In J. Moorhouse (ed.). Modem Chlor-Alkali Technology, Vol. 8, Society of Chemical Industry, Blackwell Science, Oxford (2001), p. 237. 

H. Shiroki, Y. Noaki, M. Katayose, and A. Kashiwada, Improvement of Electrolyzer and Ion Exchange Membrane for High Efficiency Chlorine and Caustic Soda Production. In R.W. Curry (ed.). Modem Chlor-Alkali Technology, vol. 6, The Royal Society of Chemistry, Cambridge (1995), p. 222. 

Impurities in brine affect electrode reaction kinetics, cell performance, the condition of some cell components, and product quality. Treatment of brine to remove these impurities has always been an essential and economically significant part of chlor-alkali technology. The brine system typically has accounted for 15% or more of the total capital cost of a plant and 5-7% of its operating cost. The adoption of membrane cells has made brine specifications more stringent and increased the complexity and eost of the treatment process. Brine purification therefore is vital to good electrolyzer performance. This section considers the effects of various impurities in all types of electrolyzer and the fundamentals of the techniques used for their control. Section 7.5 covers the practical details of the various brine purification operations. 

---