Electroosmotic flow steers neutral products and enables concentrated ethanol electroproduction from CO2

Assessing the economic potential of large-scale carbonate-formation-free CO2 electrolysis

“…3,7 In practice, a concentration higher than 10% has been experimentally demonstrated in the case of formic acid and ethanol production, using three-compartment reactors with polymeric solid-state electrolytes. [33][34][35] We also simplified the product distribution in our modeling, and the electrolyzer only produces the target product (methanol, ethanol, n-propanol, or ethylene) and H 2 . Our modeling considers the scenario where all liquid products stay in the cathode and are separated in one distillation unit.…”

“…Note that, in practice, a substantial amount of liquid products are diluted and collected in the anolyte due to crossover. 35,36 Hence, strategies to prevent the crossover of liquid products are also paramount for developing an industryscale CO 2 RR.…”

“…This simplification agrees with experiments, wherein high CO 2 single-pass utilization may not be a prerequisite of high-concentration liquid products. [33][34][35]39,40 Thus, our focus turned to the correlation between PSA costs and CO 2 single-pass utilization.…”

Electrochemical CO2 reduction in membrane-electrode assemblies

“…It is expected that the local environment should be affected by the ion-conducting nature of the membrane, the electrode activity and wettability, temperature, and the type of anolyte (e.g., KHCO 3 , KOH, or pure water). 47,94,95 Similarly, the anode reaction (i.e., OER) will also be predetermined by the membranes, anolyte, anode catalyst materials, and the reactivity of cathode. For example, the AEMs and bipolar membranes in the reverse bias should allow the use of anodes based on transition metals (e.g., Ni, Co, and Fe), whereas the CEM or bipolar membrane in the forward bias requires the previous metal-based anodes such as IrO 2 or RuO 2 , which are stable in an acidic environment.…”

Sequential vs integrated CO2 capture and electrochemical conversion: An energy comparison

“…Lastly, we assessed the energy cost of the sequential route based on future CO2 gas-fed electrolysis with no carbonate formation. Very recent reports demonstrated the potential to improve CO2 utilisation efficiency 41 by developing catalyst-membrane interface 35,42 , optimising cell operating conditions (e.g., reducing CO2 flow rates, increasing current densities, and optimising anolyte compositions and ionic strength) 37 , or supplying protons towards the cathode to regenerate CO2 from the (bi)carbonates, e.g., flowing strong acidic catholyte 20,43 , applying cation-exchange membranes 35 or bipolar membrane 42 in a reverse mode. The single-pass conversion rate remains 50% in this optimistic sequential model, meaning that 50% of the inputted CO2 feed converts to CO product and reduces the required pressureswing absorption separation energy cost.…”