(67h) Advanced Manufacturing for Electrosynthesis of Fuels and Chemicals from CO2

The combination of CO₂ electroreduction and advanced manufacturing (AM) can be used effectively for longer-term sequestration of CO₂ out of environment, as well as store renewable energy as fuels, additives, and non-fossil derived chemicals. Advanced manufacturing represents a method to rapidly create novel electrochemical reactors, particularly custom vapor-fed reactors (VFRs) for increased CO₂ consumption rates at higher current densities. Previous studies using gas diffusion electrodes (GDEs) have shown promising activity and selectivity towards ethylene and ethylene in highly alkaline electrolytes (pH > 14), but high faradaic efficiency at high current densities has been difficult to achieve in neutral electrolytes.

In this work, we demonstrate advanced manufacturing (AM) for rapid development and testing for improved performance across an evolution of reactor designs in bulk pH neutral conditions (pH < 8). Using AM VFRs and computational fluid dynamic (CFD) models, we explore activation- and mixed-control regimes across a range of operating conditions, including flow rate and electrochemical potential. Furthermore, we define a dimensionless number (Da) to identify mass transport regimes in the reactor based on several underlying mass transport mechanisms. These AM VFRs provide effective delivery of CO₂ and result in remarkable selectivity to multi-carbon products (>85% FE towards C₂₊), improved single pass CO₂ conversion (16.6%), and high ethylene (3.67%) and ethanol (3.66%) yields compared to the literature. We propose AM as a promising approach for accelerating reactor design and understanding governing phenomena while de-risking scale-up and optimization for industrial implementation.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.