Crosslinked PEO Gas Separation Membranes for Low-Temperature CO2
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Solution Overview
Problem
Existing gas separation membranes using polyethylene oxide (PEO) suffer from leaks and low carbon dioxide permeability, particularly under low-temperature conditions, due to high crystallinity and poor gas tightness.
Innovation Solution
A gas separation membrane with a separation functional layer containing crosslinked PEO, having a specific crosslinking density and a melting point below 60°C, is developed, which includes a porous support layer and optionally a protective or reinforcing layer, produced through electron beam irradiation of a PEO composition applied on a porous support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyethylene oxide is used as a dissolution-diffusion membrane material, then the membrane can selectively allow carbon dioxide to permeate, but the membrane exhibits low gas tightness and causes leaks
Solution Approach 1:
The patent combines polyethylene oxide with crosslinking agents to create a composite membrane structure. The crosslinked polyethylene oxide forms a network that maintains the selective permeability to carbon dioxide while significantly improving gas tightness and eliminating leaks through the enhanced structural integrity
Solution Approach 2:
The patent modifies the physical and chemical parameters of polyethylene oxide by controlling the degree of crosslinking and adjusting the melting point to not higher than 60°C. This parameter optimization allows the membrane to maintain low-temperature carbon dioxide permeability while achieving sufficient gas tightness
2Reliability
If polyethylene oxide is used as a dissolution-diffusion membrane, then the membrane can provide carbon dioxide selectivity, but the carbon dioxide permeability is insufficient under low-temperature conditions
Solution Approach 1:
The patent optimizes the melting point parameter of polyethylene oxide to not higher than 60°C and controls the crosslinking degree to achieve optimal carbon dioxide permeability at low temperatures. The modified parameters enable the membrane to maintain high gas-phase carbon dioxide permeability even under low-temperature operating conditions
Solution Approach 2:
The patent creates different regions within the membrane with varying crosslinking densities to optimize local properties. The crosslinked structure provides structural stability while maintaining amorphous regions that facilitate carbon dioxide transport, achieving both low-temperature permeability and mechanical integrity
3Reliability
If polyethylene oxide is used in a facilitated transport membrane, then excellent gas selectivity is achieved, but gas carrier leakage occurs causing degraded gas separation ability
Solution Approach 1:
The patent removes the gas carrier component from the membrane system entirely, transitioning from a facilitated transport mechanism to a dissolution-diffusion mechanism. This extraction of the gas carrier eliminates the leakage problem while maintaining carbon dioxide selectivity through the optimized polyethylene oxide structure
Solution Approach 2:
The patent replaces the expensive and unstable gas carrier with a simpler polyethylene oxide-based dissolution-diffusion membrane. This substitution uses a more stable, shorter-lived molecular interaction mechanism that does not require additional functional components, thereby improving overall system stability
Data Source
Figure 1~3
AI summary
As a gas separation membrane that suppresses leaks and has excellent CO2 permeability under a low temperature condition, provided is a gas separation membrane (10) including a separation functional layer (15) which contains a polymer having a polyethylene oxide structure and satisfies a condition [x] and/or a condition [y]. <Condition [x]> When, in a chromatogram obtained by measuring a solution which is obtained by chemically decomposing the separation functional layer with use of acetic anhydride and p-toluenesulfonic acid monohydrate by a gas chromatography mass spectrometry method, a peak area of a compound of formula (a) is denoted as Pa, and a peak area of a compound of formula (b) is denoted as Pb, the separation functional layer satisfies a relationship of expression (I): Pb/Pa×100≥0.03 <Condition [y]> The polymer contains crosslinked polyethylene oxide, and the separation functional layer has a melting point of 60°C or lower.