Anthropogenic CO2 emissions are one of the main contributors to climate change. Due to the reliance on fossil fuels as a feedstock, a large fraction of these emissions originate from the chemical sector, mainly through cement, steel and petrochemical industries. A renewable alternative to these non-circular carbon sources would be the electrification of processes such as the production of ethylene (C2H4), a commodity precursor molecule used to incorporate C-C bonds in a wide range of chemical products.

Ethylene and other C2+ products can be produced by means of the electrochemical reduction of CO2 using Cu electrodes. Academic research on understanding the catalytic behaviour of Cu has been steadily progressing. Additionally, the inclusion of gas diffusion electrodes (GDEs) as a porous substrate to facilitate highly accelerated gas transport has greatly advanced the performance, and with that the industrial feasibility of this reaction. Nevertheless, no industrial application for this particular reaction has been deployed due to the limited overall stability and durability of the system.

While a significant effort is put into understanding the behaviour of the catalyst and the substrate in academic literature, tuning operating conditions as a means to improve performance is generally not considered as much.

Lack of stability is a major issue for the CO2 to ethylene reaction, and while many academic efforts are directed towards solving this problem on a catalyst level, it is expected that not all problems related to upscaling and industrial operation are solvable at this scale. As such, macroscopic process control needs to be explored to identify how performance can be improved through system-level interventions.

For this research, effects of operational parameters on stability and performance have been investigated, with the goal of both improving our current testing output and to gain better understanding of effects occuring at the system level with the aim of implementing more targeted control for upscaled operations. Testing has been performed on the following parameters: temperature (20-700C), pressure differentials between cell compartments (30-300mBar deltaP), electrolyte modulation (dosing, feed-and-bleed, replacement), and electrical conditioning (initial ramping, on/off relaxation).

It was found that operating at elevated temperature, controlling the pressure differential between the gas/liquid interface and modulating the electrolyte and electrical conditions can increase performance significantly. With improved insight into operability, it has become possible to reliably perform tests for 100+ hours continuously at current densities >150mA/cm2 at 2,75V.