Crosslinked Polyamide Gas Separation Membrane with Optimized Terminal Groups
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Solution Overview
Problem
Conventional gas separation methods using crosslinked aromatic polyamide membranes have low selectivity between light gases like hydrogen or helium and carbon dioxide, resulting in low carbon dioxide separation efficiency.
Innovation Solution
A gas separation membrane with a crosslinked polyamide layer, formed by polycondensation of a polyfunctional amine and a polyfunctional acid halide, where the ratio of terminal amino groups, carboxy groups, and amide groups is optimized to enhance permeability and selectivity, and a nitro group is introduced to reduce carbon dioxide affinity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a crosslinked aromatic polyamide membrane is used for gas separation, then the membrane can provide basic separation functionality, but the separation selectivity between light gases (hydrogen/helium) and carbon dioxide is low
Solution Approach 1:
The invention changes the chemical composition parameters of the polyamide membrane by incorporating specific functional groups (nitro groups, terminal amino groups, terminal carboxy groups) and controlling their ratios. This chemical parameter modification enables the membrane to achieve high separation selectivity between light gases and carbon dioxide while maintaining practical separation efficiency
Solution Approach 2:
The invention creates a composite polyamide structure combining multiple functional groups (amide groups from polycondensation, nitro groups for reduced CO2 affinity, terminal amino groups and carboxy groups for optimized selectivity). This composite material approach allows simultaneous achievement of high selectivity and practical separation performance
2Reliability
If the membrane structure is optimized for high selectivity, then separation selectivity improves, but permeability to light gases may be reduced
Solution Approach 1:
The invention applies local quality by creating specific functional group distributions within the membrane structure. Nitro groups are introduced at specific locations to reduce carbon dioxide affinity locally, while terminal amino groups and carboxy groups are positioned to enhance selectivity. This localized functional group placement allows the membrane to simultaneously achieve high selectivity and maintain light gas permeability
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 improved permeability to light gases while increasing selectivity, effectively reducing carbon dioxide permeability and enhancing the separation efficiency of hydrogen or helium from carbon dioxide.
Implementation Method 1
a separation functional layer which is provided on the supporting membrane and includes a crosslinked polyamide obtained by polycondensation of a polyfunctional amine and a polyfunctional acid halide
Implementation Method 2
the number B of terminal carboxy groups and the number C of amide groups satisfy B/C≤0.35
Data Source
AI summary
The present invention relates to a gas separation membrane including: a supporting membrane; and a separation functional layer which is provided on the supporting membrane and includes a crosslinked polyamide obtained by polycondensation of a polyfunctional amine and a polyfunctional acid halide, in which, in the crosslinked polyamide, the number A of terminal amino groups, the number B of terminal carboxy groups, and the number C of amide groups satisfy (A+B)/C≤0.66.