Self-forming Lithiated Nickel Oxide Interphase for Stable CO2 Membrane
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Solution Overview
Problem
Current CO2 capture technologies, such as amine scrubbing, are energy-intensive and costly, limiting their widespread deployment, and silver-based mixed electron and carbon-ion conductor (MECC) membranes face issues with sintering and high costs, making them unsuitable for large-scale applications.
Innovation Solution
A mixed electron and carbon-ion conductor membrane is developed using a solid porous matrix impregnated with a molten carbonate phase, featuring a self-formed lithiated nickel oxide interphase, which enables efficient CO2 and O2 separation at high temperatures with improved stability and reduced costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silver is used as the solid electron conducting phase in MECC membranes, then chemical inertness to molten carbonate and high flux are achieved, but sintering at high temperatures causes gradual degradation in flux and the high cost becomes a barrier to scaled-up applications
Solution Approach 1:
The patent changes the material parameter from silver to nickel, which has different properties: nickel is less expensive, resistant to sintering at high temperatures, and maintains flux stability. This parameter substitution resolves the contradiction by finding a material that achieves chemical stability through oxide formation (NiO) while avoiding the sintering degradation that plagues silver-based membranes.
2Productivity
If silver-based MECC membranes are used for CO2 capture, then high flux and improved stability are achieved, but the high cost of silver makes scaled-up applications economically unviable
Solution Approach 1:
The patent replaces the expensive silver material with a much cheaper nickel-based material system. While nickel oxide does form and react with molten carbonate, this creates a functional interphase that maintains membrane performance. The cost reduction enables scaled-up applications despite any material consumption over time.
3Productivity
If conventional amine scrubbing is used for CO2 capture, then CO2 removal is achieved, but the process is energy intensive with parasitic energy about four times the thermodynamic minimum
Solution Approach 1:
The patent replaces the thermal/chemical process of amine scrubbing with an electrochemical membrane process. Instead of using heat-intensive chemical absorption and desorption cycles, the invention uses electrochemically-driven ion transport through the membrane, operating at lower temperatures and reducing parasitic energy consumption significantly.
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 membrane achieves high CO2 flux density and selectivity over nitrogen, with excellent stability for up to 450 hours at 850°C, outperforming conventional technologies and offering a cost-effective solution for CO2 capture from flue gas.
Implementation Method 1
dual-phase mixed O2−/e− and CO32− conductors represent a new class of membranes that have emerged in recent years for high-temperature, high-flux, and selective CO2 capture from flue gas and fuel gas
Implementation Method 2
the counter-ion can be provided by either a solid metal (e−) or a solid O2− conducting oxide
Implementation Method 3
an interphase disposed between the solid oxide porous substrate phase and the molten carbonate phase
Data Source
AI summary
A low-cost and easy-to-fabricate mixed e− and CO32− conducting membrane for advanced high-flux and selective electrochemical CO2 separation from flue gas is provided. The membrane includes a CO32−-conducting molten carbonate phase and an e−-conducting lithiated Ni-oxide interphase that can be formed in situ during operation. The membrane exhibits a CO2 flux density greater than 0.8 mL/(minute·cm2) at 850° C. with a selectivity ranging from about 100 to about 500 and excellent stability for up to about 450 hours. Further, the self-formed interphase Li0.4Ni1.6O2 is highly electron conducting and can provide electrons to the co-reduction of CO2 and O2 into CO32−. Such a membrane is an alternative to the conventional “size-sieving” inorganic and “dissolution-diffusion” organic counterparts for CO2 capture from flue gas.