Chapter 25. Dow (Electrochemicals)

 

 [1]

25.1.

(1890) For his undergraduate chemistry project Herbert Dow had identified Michigan brines which were unusually high in bromine. Bromine was used to produce patent medicines and photographic chemicals; the only commercial source was Die Deutsche Bromkonvention, a German cartel. Dow formed the Midland Chemical Company in 1890 to produce electrolytic bromine from brine, but when he wanted to expand into chlorine and caustic soda (chlor-alkali), his financial backers balked. Dow left in 1895 to form the Dow Chemical Company, which absorbed Midland in 1914. Though it survived competition from German bromine and British bleach, Dow remained a small company until the First World War interrupted trade with Germany. The war made it possible to move into aniline dyes and pharmaceuticals, areas dominated by the German giants, and Dow began manufacturing phenol, aspirin, and synthetic indigo. Its expertise in bromine chemistry led it to develop anti-knock gasoline additives in partnership with Ethyl Corporation. Its roots in electrolysis allowed it to extract magnesium metal from sea-water by the end of the Second World War. Its increasing proficiency with organic chemicals led it to develop silicone sealants in partnership with Corning Glass. Its early work with chlorinated fungicides led it to develop defoliants for the American military during the Vietnam conflict. Its early success with transparent polystyrene led it to develop Saran Wrap and Ziploc bags. Following its acquisition of Union Carbide, Dow Chemical would begin the twenty-first century as the largest producer of chemicals in the world.[2]

(1888) Two years before Dow formed Midland, American-born Hamilton Castner went to work for the British Aluminum Company. Aluminum manufacture at that time required elemental sodium and Castner had invented a process for making sodium from soda. Unfortunately for him, the Hall-Héroult process for making aluminum electrolytically was about to eliminate demand for sodium in aluminum manufacture. Desperately seeking a more efficient route to sodium, he began electrolyzing brine with a mercury cathode. Though the process never produced sodium cheaply enough to compete in aluminum manufacture, it produced chlorine and very pure caustic soda. It was, in fact, for the sake of caustic soda that the Austrian paper pulper, Karl Kellner, patented an almost identical process in 1894. The two Athanors resolved their initial disputes and formed the Castner-Kellner Alkali Company, which took over the British Aluminum Company in 1897.[3] Castner-Kellner would, in turn, be swallowed by Brunner Mond, which manufactured soda under license from Solvay. The availability of cheap electrolytic chlorine and caustic soda was the final nail in the coffin of the Leblanc soda process. Brunner Mond would form the core of the industrial giant, Imperial Chemical Industries (ICI), which would begin the twenty-first century as the tenth largest chemical company in the world.

(1888) When Castner went to work for British Aluminum, aluminum was a precious metal. The third most abundant element in the Earth's crust, aluminum could not be won from its ore by smelting, carbon being an insufficiently strong reducing agent. Elemental sodium was the industrial reducing agent of choice for winning aluminum from its oxide, alumina, and the high price of sodium translated into high prices for aluminum. While sodium could be produced from the electrolysis of molten sodium hydroxide, the melting point of alumina, 2051°C, ruled out the electrolysis of molten alumina as a viable industrial process. An American student, Charles Martin Hall, learned of these difficulties in his undergraduate chemistry classes at Oberlin and set out to find a flux which would lower the melting point of alumina to an attainable level. The mineral cryolite proved to be such a flux, lowering the melting point to a mere 950°C, well within the range of even modest furnaces. Using home-made batteries he produced his first electrolytic aluminum in 1886. Hall attempted to commercialize an electrolytic process in collaboration with the Cowles Electric Smelting and Aluminum Company, developers of the electric smelting furnace.[4] Meanwhile in France another college student, Paul Héroult, had independently found cryolite to be an acceptable flux for alumina and had begun using a small dynamo to produce electrolytic aluminum. It is in the interest of mortals to keep secrets and consequently Hall, Héroult, and Cowles engaged each other in lengthy legal battles. But it is not in the interest of secrets to be kept; Héroult would license his process to the British Aluminum Company and the Hall process would be adopted by the Pittsburgh Reduction Company, destined to become the Aluminum Company of America (AlCoA).

(1881) Seven years before Hall obtained his first aluminum, Thomas Alva Edison opened the first electrical power station at Pearl Street in New York City. Davy had invented the electric arc light in 1808 but the power available from batteries was insufficient for commercial application. Oersted had demonstrated electromagnetism in 1820 and Faraday had discovered electromagnetic induction in 1831, but it would fall to Werner von Siemens in 1867 to develop the dynamo, a device for converting mechanical power into electrical power. With increasing demand for electric lighting came the widespread availability of electrical power for other uses, including electrolytic production of chlorine, caustic soda, and aluminum. The early electrochemical industry grew up near sources of cheap hydroelectric power, for example, at Niagara Falls. The industry became less centralized as the AC system of Nicola Tesla and George Westinghouse made it possible to distribute electricity from remote power plants. Edison's General Electric would dwarf even the largest chemical company at the beginning of the twenty-first century, with total revenues almost five times that of Dow; in chemical sales alone it would rank as sixteenth largest chemical company in the world.

(1864) Seventeen years before the electric light, the introduction of the Solvay process had signaled the beginning of the end for the Leblanc soda process, then the central process in chemical industry. In the face of increasing opposition to its practice of dumping waste hydrogen chloride into the environment, the industry found that hydrogen chloride reacted with manganese dioxide to produce chlorine. Chlorine was further reacted with lime to produce calcium hypochlorite, known in the trade as "bleaching powder." As the Solvay process was producing soda at ever lower prices, the Leblanc industry came to rely on sales of bleaching powder to the textile and paper industries as its major source of revenue. This last refuge of the huge Leblanc industry would be taken from it by Castner and Kellner's process for electrolytic chlorine; the Leblanc process would become extinct after the First World War.

(1834) Thirty years before the first Solvay soda plant Davy's protege, Michael Faraday, first began to understand the nature of electrolysis. An electrolysis cell was simply a voltaic cell with the poles reversed; in a voltaic cell the anode, the site of oxidation, was the negative pole and the cathode, the site of reduction, was the positive pole; in the electrolysis cell the anode was forced to be positive and the cathode negative. Just as a mole of a substance can be delivered by weighing out one formula weight of that substance, a mole of electricity can be delivered by passing a current of 96,500 amps through a solution for 1 second; 96.5 amps for 100 seconds; or 9.65 amps for 1000 seconds. The quantity 96,500 amp-sec was, in essence, the formula "weight" for electricity. This new unit, the faraday, allowed stoichiometric calculations to relate the weights of reactants and products to the amount of electricity produced by a battery or consumed by an electrolytic cell.

(1825) Nine years before Faraday demonstrated the chemical equivalence of electricity, Hans Christian Oersted reacted an amalgam of potassium and mercury with aluminum chloride. When the mercury was distilled, it left behind a new element, aluminum. This remarkable metal had a low density and resisted corrosion to a degree comparable to that of gold and silver. Aluminum began to be produced commercially and might have been extremely useful had it not been so expensive. Napoleon III, for example, reserved his aluminum tableware for honored guests on special occasions. Aluminum would remain a precious metal for most of the nineteenth century, its price falling below that of silver only after the introduction of the Hall-Héroult process.

(1797) After millennia of wandering I passed from Lavoisier's Elements of Chemistry to the seventeen year old son of a Penzance wood carver. Forced to support his family by the death of his father three years earlier, this Humphry Davy had apprenticed himself to a saw-bones, but the spark burned too brightly within him to settle for a life of mere quackery. In 1798 he went to work for Thomas Beddoes investigating the therapeutic use of nitrous oxide (laughing gas) and his reputation as a chemist became such that he was appointed Professor of Chemistry at the Royal Institution in 1802. In 1808 Davy used the recently introduced voltaic battery to decompose molten potash and soda, producing two hitherto unknown elemental metals and naming them potassium and sodium, respectively. In 1810 he argued that the greenish-yellow gas liberated from common salt by manganese dioxide was, in fact, an element and gave it the name, chlorine. He further demonstrated that chlorine could be produced simply by passing an electrical current through salt water. This process, electrolysis, was to become a powerful tool, turning erstwhile products into reactants, reactants into products, in essence providing a means for driving redox reactions backwards.

Notes

[1]

Reference [29], p. 114.

[2]

Reference [54], July 29, 2002, p. 16.

[3]

See Reference [61], p. 80.

[4]

For details of the Cowles-Hall dispute see Reference [56].