Hydrogen Depolarized Anodes with Liquid Anolyte: Proof of Concept

The development of depolarized electrodes may be considered as an improvement on economic and environmental aspects for the chemistry industry. In this regard, using a hydrogen depolarized anode (HDA) to produce protons from hydrogen oxidation could be coupled with a membrane process to concentrate valuable products. In particular, the actual standard anode used in a recent industrial lithium hydroxide electromembrane process could be replaced by an HDA. This change could lower the electric consumption and production costs. However, this evolution requires the development of an electro cell properly adaptable to the current process. In this study, we propose a proof of concept for this technology with a dedicated installation using a sulfuric acid electrolyte. Based on materials commonly used in the field of fuel cells, which share some fundamental aspects, a general understanding of hydrogen depolarized anodes will be presented. The goal is to develop an electro cell that allows anode monitoring to understand ADH operation and to compare different conditions. In this purpose, different measurements are combined to measure aspects of the ADH such as resistance, mass transfer, and kinetic overpotentials. The proposed architecture can successfully sustain the reaction at 4 kA m −1 with several mV overpotentials. But after several 10-h periods, anode operation deteriorates until reaction failure. The impact of water through the anode is identified as an important parameter to ensure long-term stability. The results obtained in this study are a first step in hydrogen depolarized anode development; they confirm the interest in this technology and identify various improvement pathways to continue its progress. Graphical abstract Development of a dedicated electrochemical cell allows testing the ability of a hydrogen depolarized anode to convert hydrogen to protons. The use of materials inspired by fuel cell technology was successfully adapted to a hydrogen depolarized anode. Water migration appears as a key factor, and catalytic layer flooding has to be controlled to prevent cell failure.