Halogen cycles as important contribution for stabilising the electricity grid and for de-fossilisation of a future industrial society
Organic halogenated compounds and polymers feature unique properties. They are key components for many modern technologies. However, these compounds are environmentally problematic, and their recycling is often based on high-temperature total oxidation by combustion. This leads to high energy consumption, release of large amounts of CO2, and loss of the underlying carbon skeleton. Halocycles targets a disruptive paradigm, that is the use of electrochemical processes to split the carbon-halogen bonds and recover the halogens as anions as well as the intact carbon skeleton as building blocks for a circular economy based around halogenated compounds. Halocycles targets electrosynthetic approaches capable of operating with intermittent electricity supplies, so that excess electricity produced from sun or wind power can be utilised to drive these processes.
Many of these highly halogenated compounds are widely used due to their outstanding stability. In particular, the use and sensible recycling of polychlorinated compounds such as PVC or lindane waste represent a central challenge, the electrochemical conversion also enables a dioxin-free route.
The electro-conversion of highly fluorinated residual streams (Teflon, PFA, etc.) will pose the greatest challenge, as it is necessary to work at strongly negative electrical potentials. For later applicability requires not only robust electro-conversion but also suitable processes, analysis, and purification of the potentially complex mixtures.
When converting highly halogenated compounds, toxicological consideration is essential. Furthermore, both the flexible electrochemical stage and the process engineering steps will be analysed in terms of materials and economics to assess the contribution to a possible halogen circular economy. Here, we expect that realising the goals of Halocycles will not only increase resource efficiency, but also open up further opportunities for raw material sovereignty, which has far-reaching implications for value creation from residual material streams and pave a path to a circular halogen economy.