Ionic Liquid CO2 Membranes for Separation Below 1 kPa
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Solution Overview
Problem
Existing carbon dioxide separation membranes struggle to efficiently separate and recover carbon dioxide at low partial pressures, particularly below 1 kPa, limiting their effectiveness in capturing carbon dioxide from atmospheric sources.
Innovation Solution
A carbon dioxide separation membrane using an ionic liquid composition comprising an ionic liquid (I) with aminium cations and bis(trifluoromethylsulfonyl)amide anions, combined with an ionic liquid (II) lacking primary or secondary amino groups and featuring oxoacid anions, enhances the selectivity and permeability of carbon dioxide under low partial pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polymer membrane is used for carbon dioxide separation, then the membrane structure is stable and easy to manufacture, but the permeability and selectivity ratio of carbon dioxide cannot be improved simultaneously
Solution Approach 1:
The patent uses a composite membrane structure combining a porous polymer support layer with a liquid membrane layer containing ionic liquid. This composite approach allows the polymer base to provide structural stability while the ionic liquid layer provides enhanced CO2 permeability and selectivity through chemical absorption mechanisms, resolving the contradiction between stability and productivity.
Solution Approach 2:
The patent employs a porous polymer support layer with controlled porosity (30-80%) that allows gas permeation while maintaining structural integrity. The porous structure enables the liquid membrane to be impregnated while maintaining mechanical strength, achieving both stability and improved gas transport properties.
2Reliability
If a liquid membrane containing a volatile solvent is used for carbon dioxide separation, then the selectivity ratio is improved, but the solvent volatilizes and deactivates the membrane function over time
Solution Approach 1:
The patent changes the physical parameter of volatility by selecting ionic liquids with extremely low vapor pressure instead of conventional volatile solvents. This parameter change eliminates solvent volatilization while maintaining the liquid membrane's CO2 separation function, resolving the contradiction between selectivity and substance loss.
Solution Approach 2:
The patent replaces the volatile solvent that degrades over time with an ionic liquid that is non-volatile and stable. This substitution eliminates the short-living nature of conventional solvents while maintaining effective CO2 separation performance, preventing functional degradation.
3Adaptability or versatility
If the partial pressure of carbon dioxide is reduced to 1 kPa or lower for atmospheric separation, then the application range is expanded, but the separation efficiency of existing membranes decreases
Solution Approach 1:
The patent changes the absorption mechanism from purely physical absorption to chemical absorption using ionic liquids with amino groups that react with CO2. This chemical mechanism maintains high affinity for CO2 even at low partial pressures (1 kPa or lower), enabling effective separation across expanded application ranges including atmospheric CO2 capture.
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 ionic liquid composition improves carbon dioxide permeability and selectivity ratio, enabling efficient separation and recovery from high to low partial pressures, including 1 kPa or lower.
Implementation Method 1
a physical absorption method for separating and recovering carbon dioxide, in which carbon dioxide is separated by absorbing carbon dioxide physically, not by chemical reaction, into a solvent selectively from a mixed gas containing carbon dioxide
Implementation Method 2
a membrane separation method, in which a gas containing carbon dioxide, the gas to be separated, is fed from one side of a membrane, and carbon dioxide in the gas is selectively transported to the other side of the membrane to separate using the partial pressure difference of carbon dioxide between the front and rear sides of the membrane
Data Source
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AI summary
An object of the present invention is to provide an ionic liquid composition for a carbon dioxide separation membrane, a carbon dioxide separation membrane retaining the composition in voids, and a carbon dioxide concentration apparatus provided with the carbon dioxide separation membrane that can be used to separate carbon dioxide from high partial pressure to low partial pressure, especially 1 kPa or lower. The permeability of CO2 and CO2 selectivity ratio of the carbon dioxide separation membrane can be improved, and carbon dioxide from high partial pressure to a low partial pressure of 1 kPa or lower can be selectively separated and recycled by using an ionic liquid composition prepared by combining: an ionic liquid (I) that is an aminium having one or more primary or secondary amino groups and an ethylenediamine or propylenediamine backbone in the cation; and an ionic liquid (II) in which the cation has no primary or secondary amino group and the anion is an oxoacid anion.