- Date 2024-01-24
Chlorine (Cl2) is one of the most important base chemicals in the world and is used industrially for the production of numerous materials such as polymers, drugs and agrochemicals. To meet the global demand for chlorine, it is produced worldwide at a rate of over 90 million tons per year. In Germany, about 5.5 million tons of chlorine are produced, mainly by chlor-alkali electrolysis. This consumes about 2.5% of the German electricity (about 7% in NRW) per year.
Currently, the production of chlorine by chlor-alkali electrolysis is highly dependent on base-load electricity. Although chlor-alkali electrolysis is in principle adaptable to electricity fluctuations, most downstream processes that use chlorine are not. To produce chlorine with renewable energy, intermediate storage of the chlorine is useful. Usually chlorine is stored by pressure liquefaction, which is problematic and energy consuming and therefore mostly avoided. Another problem is the transport of pressure-liquefied chlorine, e.g. by rail, especially if this leads through heavily populated areas.
In recent years, the workgroup Riedel, located at the Institute for Chemistry and Biochemistry - Inorganic Chemistry at the Freien Universität Berlin, has developed a new type of chlorine storage based on so-called polychlorides. In contrast to the usual pressure liquefaction of chlorine, it is stored in the form of an ionic liquid at room temperature with virtually no pressure and can thus be transported and, if necessary, used directly. Due to the much lower vapor pressure of the storage liquid, a lower release of chlorine is to be expected, e.g. in the event of a leakage or an accident. With this new storage material, the current restrictions on the storage and transport of chlorine could be overcome, so that renewable energies can be used more efficiently and a flexibilization of the chlorine industry can be achieved.
The text source and more information can be found here: Freie Universität Berlin, Inorganic Chemistry, Hasenstab-Riedel Group, A More Sustainable Chlorine Chemistry and Technology https://www.bcp.fu-berlin.de/en/chemie/chemie/forschung/InorgChem/agriedel/Forschung/Chlorchemie/index.html