Ag-Recycling from electrolysis electrodes


Deutz, Sarah © Copyright: Lehrstuhl fuer Technische Thermodynamik der RWTH Aachen


Sarah Deutz

Group Leader Energy Systems Engineering (on parental leave)


+49 241 80 95391




Elektrolyseur Copyright: © Covestro AG

Since several years, Covestro develops a highly efficient electrode technology for the chlor-alkali electrolysis, called oxygen depolarized cathode (ODC). Used ODCs contain 70% Ag, 25% Ni, and 5% PTFE. The recycling of the electrodes is severely impeded by the component PTFE. If PTFE is removed prior to the recycling process, the recycling performance could be improved. Thus, the project aims to develop an economically and ecologically efficient recycling process for Ag and Ni from the chlor-alkali electrolysis electrodes at technical scale. The recycled silver is intended to be used for production of highly active catalysts for new ODCs.



Recycling Icon Copyright: © LTT

In the project, alternative processes are considered as possible recycling processes at technical scale and evaluated under environmental and economic aspects. In work package 1, the PTFE removal is studied, followed by the silver-nickel-separation in work package 2. Work package 3 contains the manufacturing and functional tests of the electrodes. Subsequently, in work package 4, the economic and environmental assessment of the recycling processes is conducted.

The LTT focusses on the environmental assessment of the developed recycling processes. For environmental assessment, the standardized method life cycle assessment is applied. Life cycle assessment enables the evaluation of resource savings, as well as additional environmental impacts of the recycling processes. Thus, it can be analyzed which recycling process is environmentally most beneficial. Furthermore, the LTT evaluates and compares the recycling alternatives by means of economic indicators.


Project Details

Project Duration

March 1, 2015 to August 31, 2018


The project is funded in the support measure r4 – Innovative Technologien für Ressourceneffizienz – Forschung zur Bereitstellung wirtschaftsstrategischer Rohstoffe by the German Federal Ministry of Education and Research.