Electrochemical Reduction of CO₂ in Tubular Flow Cells under Gas–Liquid Taylor Flow

Abstract

Electrochemical reduction of CO 2 using renewable energy is a promising avenue for sustainable production of bulk chemicals. However, CO 2 electrolysis in aqueous systems is severely limited by mass transfer, leading to low reactor performance insufficient for industrial application. This paper shows that structured reactors operated under gas–liquid Taylor flow can overcome these limitations and significantly improve the reactor performance. This is achieved by reducing the boundary layer for mass transfer to the thin liquid film between the CO 2 bubbles and the electrode. This work aims to understand the relationship between process conditions, mass transfer, and reactor performance by developing an easy-to-use analytical model. We find that the film thickness and the volume ratio of CO 2 /electrolyte fed to the reactor significantly affect the current density and the faradaic efficiency. Additionally, we find industrially relevant performance when operating the reactor at an elevated pressure beyond 5 bar. We compare our predictions with numerical simulations based on the unit cell approach, showing good agreement for a large window of operating parameters, illustrating when the easy-to-use predictive expressions for the current density and faradaic efficiency can be applied.

Scale-Dependent Techno-Economic Analysis of CO2 Capture and Electroreduction to Ethylene

“…It was assumed that the BPM configuration operated without cations in the anolyte and instead operated on a deionized (DI) water anolyte. Electrolyzer performance (e.g., CO 2 utilization, selectivity, voltage, and current density) may change as a function of scale, 19,45 but as a simplification, the electrolyzer performance remained constant for all production scales in this work. In both electrolyzer configurations, the evolution of O 2 occurred at the anode.…”

“…The scale optimum for the integrated CO 2 RR process depends on the behavior of the upstream, downstream, and electrolysis technologies, each with their own scale-up curves. The scale optimum for the overall process can change with future technological improvements (e.g., implementing an adsorbent-based approach for downstream C 2 H 4 purification 69,70 or improving electrolyzer performance) or refinements to the TEA (e.g., accounting for scale-dependent electrolyzers OPEX and CAPEX 19,45,51 ).…”

Techno-economic Assessment of CO2 Electrolysis: How Interdependencies between Model Variables Propagate Across Different Modeling Scales

“…While it should be noted that the optima in this work are derived based on simplified reaction mechanisms and design considerations and therefore should not be taken as fixed optimum values for future electrolyser designs, the used approach nonetheless highlights the dependency of the mechanistic detail and interdependencies between performance variables on the economic viability of an electrolyser design. This work further presents a tool to evaluate electrolyser design choices based on an economic objective, which in its generic form can be applied to various electrolyser designs ,− and CO 2 -reduction products, such as CO or formate. ,, For different electrolyser designs and products, the modeling assumptions, and hence, the economic predictions, are highly dependent on the available data; therefore, it is important to (a) move toward more holistic, multiscale modeling approaches in the field of CO 2 electrolysis and to (b) communicate measured or targeted electrolyser performance with all applicable boundary conditions, including achieved conversions.…”

Tailoring hydrophilic and hydrophobic microenvironments for gas–liquid–solid triphase electrochemical reactions

“…21d). 147 They suggested a tube-in-tube configuration with a tubular MEA as an inner cathode and outer tubes as an anode. CO 2 bubbles can be introduced along the inner tube in the form of Taylor flow.…”