Electrochemical CO2 Separator With Anion-Exchange Membrane
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Solution Overview
Problem
Existing technologies for direct air capture (DAC) of carbon dioxide are inefficient and costly, particularly due to high energy consumption and the need for expensive hydrogen or oxygen supplies, and they fail to effectively separate CO2 from air at distributed sources.
Innovation Solution
An electrochemically driven carbon dioxide separator (EDCS) using nickel hydroxide electrodes and an anion exchange polymer membrane to convert CO2 into bicarbonate and carbonate ions, which are then decomposed to release pure CO2, with alternating current flow to optimize electrode efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional electrochemical reactions (ORR, HER, HOR, OER) are used in EDCS, then CO2 separation can be achieved, but energy consumption increases significantly due to kinetic overpotential and coproduct losses
Solution Approach 1:
The patent changes the chemical parameters of the electrochemical reactions by using zinc-based reactions (Zn + 2OH- → ZnO + H2O + 2e- at anode and ZnO + H2O + 2e- → Zn + 2OH- at cathode) instead of conventional hydrogen/oxygen reactions. This parameter change eliminates kinetic overpotential issues and coproduct losses, achieving both low energy consumption and high CO2 separation efficiency
Solution Approach 2:
The patent employs zinc as a sacrificial anode material that can be easily replenished, replacing expensive and energy-intensive hydrogen supply systems. The zinc anode is consumed during operation but can be replaced affordably, eliminating the need for continuous hydrogen production and supply infrastructure
2Ease of manufacture
If hydrogen is supplied for HOR anode reaction, then CO2 separation can proceed, but cost increases due to energy-intensive hydrogen production
Solution Approach 1:
The patent replaces expensive hydrogen supply with inexpensive zinc anodes that are easily manufactured and replaced. Zinc is abundant and can be processed into electrode form at low cost, eliminating dependence on energy-intensive hydrogen production while maintaining effective CO2 separation performance
3Device complexity
If OER is used at anode, then CO2 separation can occur, but additional downstream separation is required due to CO2 mixture with oxygen coproduct
Solution Approach 1:
The patent extracts the oxygen evolution step from the CO2 separation process by using zinc-based electrochemical reactions that do not produce oxygen coproduct. The anode reaction Zn + 2OH- → ZnO + H2O + 2e- consumes hydroxide without generating gaseous coproducts, thereby extracting the purification function from the separation system and eliminating the need for downstream gas separation equipment
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
The EDCS achieves efficient and cost-effective CO2 separation from air with minimal energy consumption, producing high-purity CO2 for utilization or sequestration, and can be integrated with metal-air batteries to reduce CO2 levels below 20 ppm.
Implementation Method 1
a membrane adjacent to and separating the two electrodes, the membrane comprising an anion exchange polymer
Implementation Method 2
the charge storage compound being capable of reacting to form hydroxide when acting as the cathode and reacting to consume hydroxide when acting as the anode
Implementation Method 3
CO2 reacts with strong bases like hydroxide anions to form carbonate and bicarbonate anions
Data Source
AI summary
Electrochemical devices including electrochemically-driven carbon dioxide separators are disclosed, the devices including electrodes comprised of an anion exchange polymer and a charge storage compound such as nickel hydroxide and a membrane comprising an anion exchange polymer, the membrane having a channel for inflow of a carbon dioxide-containing gas within the membrane.