Gas Diffusion Electrode Aprotic Solvent CO2 Reduction

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Solution Overview

Problem

Current electrochemical processes for CO2 reduction to oxalate in aqueous solutions face limitations in achieving high current densities and Faradaic Efficiency (FE) due to mass transport limitations and side reactions, particularly the Hydrogen Evolution Reaction (HER), which hinder industrial-scale application.

Innovation Solution

The use of Gas Diffusion Electrodes (GDEs) in an aprotic solvent with gaseous CO2 supply enhances mass transport to the active site, allowing for high current densities (>100 mA·cm−2) and improved selectivity towards oxalate production by reducing the diffusion path and minimizing unwanted side reactions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If aqueous solution is used for CO2 reduction, then the process is simpler and cheaper, but mass transport limitations and side reactions (HER) reduce current density and Faradaic Efficiency

Engineering Contradiction:

Improveprocess simplicityVSAvoidcurrent density

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The patent changes the solvent parameter from aqueous to aprotic (acetonitrile), which fundamentally alters the electrochemical environment. This parameter change eliminates proton availability for HER, increases CO2 solubility, and enables high current densities (>100 mA·cm−2) with high Faradaic Efficiency for oxalate production

Inventive Principle:

Principle #35Parameter changes

2Productivity

If gaseous CO2 is supplied to enhance mass transport, then Faradaic Efficiency improves, but device complexity increases due to GDE requirement

Engineering Contradiction:

ImproveFaradaic EfficiencyVSAvoidelectrode structure

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent employs a Gas Diffusion Electrode (GDE) with porous structure that allows gaseous CO2 to diffuse through the porous matrix to the catalytic sites. This porous material enables direct gas-liquid-solid contact, achieving high mass transport and Faradaic Efficiency while maintaining a practical electrode design

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The GDE acts as an intermediary component that facilitates the interface between gaseous CO2 supply and the liquid electrolyte environment. It mediates mass transport by allowing CO2 diffusion through its porous structure to reach the catalytic sites immersed in the aprotic solvent

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If homogeneous catalysts are used, then selectivity to oxalate improves, but product/catalyst separation becomes difficult and costs increase

Engineering Contradiction:

ImproveselectivityVSAvoidproduct separation

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent extracts the catalytic function from the bulk solution and immobilizes it on the GDE surface. This takes out the catalyst from the homogeneous phase and places it in a fixed, separable position, allowing easy product-catalyst separation while maintaining high selectivity for oxalate production

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent employs a simple, replaceable GDE structure with immobilized catalyst that can be easily discarded or regenerated. This avoids the need for complex catalyst recovery systems, making the process economically viable despite using precious metal catalysts

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration achieves industrial-relevant current densities and Faradaic Efficiencies for CO2 reduction to oxalate, reducing the need for costly purification steps and increasing the process's overall efficiency and selectivity.

Implementation Method 1

Gas Diffusion Electrode (GDE) with an aprotic solvent in such conversion of gaseous CO2

Methodology Applied

Scientific EffectGas diffusion: Diffusion

Implementation Method 2

enhances mass transport to the active site, allowing for high current densities (>100 mA·cm−2) and improved selectivity

Methodology Applied

Scientific EffectMass transport enhancement: Diffusion

Implementation Method 3

The electrochemical reduction of CO2 is an emerging technology to valorise captured CO2 from waste streams or the atmosphere to produce value-added chemical or fuels

Methodology Applied

Scientific EffectElectrochemical reduction: Electrolysis

Implementation Method 4

suitable aprotic solvents (such as DMSO, DMF, AN, PC) have a higher CO2 solubility than water, allowing the reduction at higher current

Methodology Applied

Scientific EffectGas solubility enhancement: Solvation

Data Source

PatentUS11898259B2Electrochemical CO<sub>2 </sub>conversion

Publication Date: 2024.02.13 VLAAMSE INSTELLING VOOR TECHNOLOGISCH ONDERZOEK NV (VITO)

AI summary

The present invention is related to the electrochemical conversion of CO2 and provides the use of Gas Diffusion Electrode with an aprotic solvent in such conversion of CO2 as well as an electrochemical cell for use in such conversion. The application and electrochemical cell as herein provided are particularly useful in the conversion of CO2 into oxalate/oxalic acid.