Feed and Bleed Operating Mode for Electrochemical Flow Cells: Challenges, Solutions and Practical Insights

ChemElectroChem, vol. 12

Abstract

Abstract Electrochemical processes offer promising routes to defossilize the chemical industry by integrating low‐carbon electricity. However, bridging the gap between lab‐scale experimental studies and pilot‐scale industrial applications is still challenging: Lab‐scale electrochemical flow cells typically operate in batch or single‐pass mode, with each mode facing limitations regarding the steady‐state operation at industrially relevant conditions. This work introduces the “feed and bleed” operating mode with continuous exchange of a recirculated electrolyte stream, which enables versatile steady‐state operation. The “feed and bleed” mode is compared to batch and single‐pass operation. We develop a mathematical model for “feed and bleed” operation and validate the model experimentally. Additionally, this work introduces a 3D‐printed phase separator coupled with lab‐scale flow cells to separate gas from the recirculated liquid stream. Batch, single‐pass, and “feed and bleed” operation are demonstrated by methanol oxidation to formate at 200 mA/cm2 in a 25 cm2 flow cell. This provides an experimental comparison concerning product/reactant concentration, conversion, and Faraday efficiency. The comparison highlights the characteristics of each operation mode for the electrosynthesis of chemicals, showcasing the unique characteristics of the feed and bleed mode, which enables steady‐state operation at industrially‐relevant conditions with high product concentration.

Authors 5

1. Jonas Baessler Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University Aachener Verfahrenstechnik – Chemical Process Engineering Forckenbeckstr. 51 52074 Aachen Germany

2. Malte Wehner Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University Aachener Verfahrenstechnik – Chemical Process Engineering Forckenbeckstr. 51 52074 Aachen Germany

3. Mojtaba Mohseni Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University Aachener Verfahrenstechnik – Chemical Process Engineering Forckenbeckstr. 51 52074 Aachen Germany

4. Matthias Weßling Aachen

   DWI – Leibniz Institute for Interactive Materials · RWTH Aachen University

   Affiliation as printed

   DWI – Leibniz Institute for Interactive Materials Forckenbeckstr. 50 52074 Aachen Germany

   RWTH Aachen University Aachener Verfahrenstechnik – Chemical Process Engineering Forckenbeckstr. 51 52074 Aachen Germany

5. Robert Keller corresponding Aachen

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University Aachener Verfahrenstechnik – Chemical Process Engineering Forckenbeckstr. 51 52074 Aachen Germany