11. Off Gas Cleaning by Adsorption

Some process steps in the recycling process containing a significant amount of volatile organic compounds, such as shredding and drying, need to be inertised by flushing with dry nitrogen. Consequently, the off gas of this inertization is loaded with electrolyte or extraction solvents. Due to environmental restrictions, this off gas has to be cleaned before it is released. This chapter addresses the off gas cleaning with adsorption onto activated carbon and gives a basic understanding of the operation mode of a fixed bed adsorber and the database to design an adsorptive off gas cleaning. Relevant data of adsorption equilibria of single as well as binary mixtures of electrolyte components onto activated carbon at temperatures from 20 to 60 °C are presented. Additionally, binary equilibria were calculated with the Ideal Adsorbed Solution Theory and compared to experimental results. Finally, results of the adsorption in a fixed bed are discussed. Breakthrough behavior and temperature profiles of the adsorption process are presented and compared to the adsorption equilibria. Another focus is set onto decomposed electrolyte components that may occur during the lifetime of a battery, the recycling process and the adsorption itself. These decomposition products can affect the adsorption equilibrium and therefore have to be considered.