It is impossible to imagine the chemical industry without chlorine. Around two-thirds of all products are based on this important raw material – for example polymers, pharmaceuticals, and chemicals for drinking water treatment. Chlorine production is one of the most energy-intensive processes of all and therefore a real cost factor.
However, Covestro has now pushed the boundaries of what is possible in this area yet again. Together with partners from industry, the company has developed a technology that can reduce the amount of energy required for chlorine production by 25 percent. The innovative oxygen depolarized cathode (ODC) is already in use in Germany at the Krefeld-Uerdingen site at partial capacity.
The new process is fundamentally based on the common membrane process of chloralkali electrolysis, in which chlorine, caustic soda, and hydrogen are extracted from table salt (NaCl) and water. However, there is one subtle but crucial difference: the hydrogen-generating electrode that is usually used is replaced by an oxygen depolarized cathode. The supply of oxygen to the cathode subsequently prevents the formation of hydrogen. This way, only chlorine and caustic soda can be obtained.
The German Federal Ministry of Education and Research (Bundesministerium für Bildung und Forschung – BMBF) funded the project as part of the “Research for Sustainability” (FONA) initiative. The technology was awarded the 2019 Covestro Science Medal for outstanding innovative and sustainable performance.
The result is impressive: If the ODC technology were to be used throughout Germany for chlorine production, Germany could reduce its total electricity requirements by around one percent. That would be roughly equivalent to the annual consumption of a major city such as Cologne.