Future Developments

Abstract

Chapter 2 recounts some of the history of chlor-alkali technology and production. While very important industrially, the process is an old one and, as one of the few examples of large-scale electrochemical production, somewhat outside the mainstream of chemical research and development. The industry is part of the commodity chemical business and has often faced difficult economic problems. All this seems a recipe for technological stagnation. However, the past few decades have seen two major developments that have had profound effects on the technology and economics of production. These are the introduction of metal anodes and the partial substitution of membrane technology for the older diaphragm and mercury technologies. The first of these was made possible by the development of durable, low-voltage coatings that could be applied to titanium. Metal anodes offered many advantages over graphite. Furthermore, direct replacement of graphite by metal anodes of essentially the same dimensions was also rather a simple matter. The changeout therefore was rapid. Membrane technology, on the other hand, required extensive changes in the process. Except for the “membrane-bag” cells, which were a compromise approach, these changes included new electrolyzers. This is quite an expensive proposition, and the energy economy of the membrane cell has not in itself justified wholesale conversion. When a producer has the opportunity to expand conversion, new facilities are easier to justify, but the economic state of the industry has, for the most part, been only fair or poor. The conversion to membrane technology has therefore been slow, and only very recently has the membrane process approached the total installed capacities of the other technologies.