Differential pressure CO2 electrolysis opens the way for direct coupling to industrial processes
Stephan Heuser, Lucas Hoof, Kevinjeorjios Pellumbi, Jan Niklas Oberndorf, Lennart Krämer, Dennis Blaudszun, Kai junge Puring, Michael Prokein, Nils Mölders, Andreas Kilzer, Marcus Petermann, Ulf‐Peter Apfel
Abstract
Pressurized electrochemical carbon dioxide reduction (CO 2 R) offers a pathway to enhance selectivity, current density, and process integration. While elevated pressures improve CO 2 R performance, differential pressure operation above 10 bar between cathode and anode remains underexplored. This study introduces an innovative test facility and a continuous high-pressure reactor with a zero-gap architecture, enabling gaseous CO 2 electrolysis at a differential pressure of 40 bar(g). Using a bipolar membrane electrode assembly eliminates the need for CO 2 humidification, and using ultrapure water as the sole proton source creates a salt-free environment without acid or base additives. This setup achieved a Faraday efficiency for CO of 81% at 500 mA cm −2 , efficient CO 2 R with a CO 2 excess ( λ CO2 ) below 4, and single-pass conversion rates up to 26% at 40 bar(g). The pressurized CO 2 R outlet streams have low CO 2 content, enabling direct integration into downstream chemical processes. This marks a key advancement toward scalable, energy-efficient industrial CO 2 electrolysis systems.