A Quantitative Analysis of Electrochemical CO2 Reduction on Copper in Organic Amide and Nitrile-Based Electrolytes

Aqueous electrolytes used in CO2 electroreduction typically have a CO2 solubility of around 34 mM under ambient conditions, contributing to mass transfer limitations in the system. Non-aqueous electrolytes exhibit higher CO2 solubility (by 5–8-fold) and also provide possibilities to suppress the undesired hydrogen evolution reaction (HER). On...

High-pressure electrochemical reduction of CO₂ to formic acid/formate: Effect of pH on the downstream separation process and economics

We use a high-pressure semicontinuous batch electrochemical reactor with a tin-based cathode to demonstrate that it is possible to efficiently convert CO₂ to formic acid (FA) in low-pH (i.e., pH < pK_a) electrolyte solutions. The effects of CO₂ pressure (up to 50 bar), bipolar membranes, and electrolyte (K...

Electroreduction of CO₂/CO to C₂Products: Process Modeling, Downstream Separation, System Integration, and Economic Analysis

Direct electrochemical reduction of CO2 to C2 products such as ethylene is more efficient in alkaline media, but it suffers from parasitic loss of reactants due to (bi)carbonate formation. A two-step process where the CO2 is first electrochemically reduced to CO and subsequently converted to desired C2 products has the potential to overcome...

Liquid-Liquid Extraction of Formic Acid with 2-Methyltetrahydrofuran: Experiments, Process Modeling, and Economics

Formic acid (FA) is an interesting hydrogen (H2) and carbon monoxide (CO) carrier that can be produced by the electrochemical reduction of carbon dioxide (CO2) using renewable energy. The separation of FA from water is challenging due to the strong (cross)association of the components and the presence of a high boiling azeotrope. For the...

Electrochemical Reduction of CO₂to Oxalic Acid: Experiments, Process Modeling, and Economics

We performed H-cell and flow cell experiments to study the electrochemical reduction of CO2 to oxalic acid (OA) on a lead (Pb) cathode in various nonaqueous solvents. The effects of anolyte, catholyte, supporting electrolyte, temperature, water content, and cathode potential on the Faraday efficiency (FE), current density (CD), and product...

Surface Coverage as an Important Parameter for Predicting Selectivity Trends in Electrochemical CO₂ Reduction

The electrochemical CO2 reduction reaction (CO2RR) is important for a sustainable future. Key insights into the reaction pathways have been obtained by density functional theory (DFT) analysis, but so far, DFT has been unable to give an overall understanding of selectivity trends without important caveats. We show that an unconsidered...

High pressure electrochemical reduction of CO₂ to formic acid/formate: A comparison between bipolar membranes and cation exchange membranes

A high pressure semicontinuous batch electrolyzer is used to convert CO₂ to formic acid/formate on a tin-based cathode using bipolar membranes (BPMs) and cation exchange membranes (CEMs). The effects of CO₂ pressure up to 50 bar, electrolyte concentration, flow rate, cell potential, and the two types of membranes on the...

Modeling the electrochemical conversion of carbon dioxide to formic acid or formate at elevated pressures

In this work a model of an elevated pressure CO₂ electrolyzer producing primarily formate or formic acid is presented. It consists of three parts: A model of the bulk electrolyte, the diffusion layer, and the electrode surface. Data from the literature was used to validate both the bulk portion of the model, as well as the overall...