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Elemental aluminium cannot be produced by the electrolysis of an aqueous aluminium salt, because hydronium ions readily oxidize elemental aluminium. Although a molten aluminium salt could be used instead, aluminium oxide has a melting point of 2072 °C (3762°F) [4] so electrolysing it is impractical.
Considering the industrial production of hydrogen, and using current best processes for water electrolysis (PEM or alkaline electrolysis) which have an effective electrical efficiency of 70–82%, [70] [71] [72] producing 1 kg of hydrogen (which has a specific energy of 143 MJ/kg or about 40 kWh/kg) requires 50–55 kWh of electricity.
An electrolytic process is the use of electrolysis industrially to refine metals or compounds at a high purity and low cost. Some examples are the Hall-Héroult process [1] used for aluminium, or the production of hydrogen from water. Electrolysis is usually done in bulk using hundreds of sheets of metal connected to an electric power source ...
Its density is also lower than that of liquid aluminium (2 vs 2.3 g/cm 3), which allows natural separation of the product from the salt at the bottom of the cell. The cryolite ratio (NaF/AlF 3 ) in pure cryolite is 3, with a melting temperature of 1010 °C, and it forms a eutectic with 11% alumina at 960 °C.
The National Renewable Energy Laboratory estimated in 2006 that 1 kg of hydrogen (roughly equivalent to 3 kg, or 4 liters, of petroleum in energy terms) could be produced by wind powered electrolysis for between US$5.55 in the near term and US$2.27 in the longer term.
Electrochemistry. English chemist John Daniell (left) and physicist Michael Faraday (right), both credited as founders of electrochemistry. Electrochemistry is the branch of physical chemistry concerned with the relationship between electrical potential difference and identifiable chemical change. These reactions involve electrons moving via an ...
Electrometallurgy is a method in metallurgy that uses electrical energy to produce metals by electrolysis. It is usually the last stage in metal production and is therefore preceded by pyrometallurgical or hydrometallurgical operations. [1] The electrolysis can be done on a molten metal oxide (smelt electrolysis) which is used for example to ...
The Castner process for production of sodium metal was introduced in 1888 by Hamilton Castner. At that time (prior to the introduction in the same year of the Hall-Héroult process) the primary use for sodium metal was as a reducing agent to produce aluminium from its purified ores. The Castner process reduced the cost of producing sodium in ...