Crosslinked Polyimide Gas Separation Membrane
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Solution Overview
Problem
Existing gas separation membranes face challenges in achieving high gas permeability, separation selectivity, and mechanical strength, especially under high pressure and high carbon dioxide concentration conditions, and are prone to plasticization and damage from impurities like water and hydrocarbons.
Innovation Solution
A gas separation composite membrane is developed with a crosslinked polyimide resin layer and a gas-permeable supporting layer, utilizing specific crosslinking chains and polyimide compounds with optimized repeating units to enhance gas permeability and selectivity, and incorporating a nonwoven fabric for mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single raw material is processed into an asymmetric membrane to achieve high gas permeability and separation selectivity, then the membrane can satisfy high gas permeability and separation selectivity requirements, but the mechanical strength becomes insufficient
Solution Approach 1:
The patent employs a composite membrane structure consisting of a skin layer made from polyimide compound and a support layer made from polysulfone or polyether sulfone. This composite structure allows the skin layer to provide high gas permeability and separation selectivity while the support layer provides mechanical strength, thereby resolving the contradiction between permeability and mechanical strength.
2Productivity
If the membrane is made thin to achieve high gas permeability, then gas permeability is improved, but the membrane becomes susceptible to plasticization under high pressure and high carbon dioxide concentration conditions
Solution Approach 1:
The patent changes the chemical composition parameters by selecting specific polyimide compounds with particular molecular structures and incorporating them into the skin layer. This compositional parameter change enhances the membrane's resistance to plasticization under high pressure and high CO2 concentration conditions while maintaining high gas permeability through the thin skin layer structure.
3Manufacturing precision
If conventional polyimide or cellulose membranes are used for natural gas purification, then separation capability is achieved, but the membranes suffer damage from impurities such as water, hydrogen sulfide, and hydrocarbons over time
Solution Approach 1:
The patent changes the chemical composition by selecting specific polyimide compounds with enhanced chemical stability and incorporating them into the skin layer. This compositional parameter change provides resistance against degradation from impurities such as water, hydrogen sulfide, and hydrocarbons, thereby improving long-term chemical stability while maintaining separation selectivity.
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 gas permeability, separation selectivity, and durability, effectively resisting deterioration from water and organic components, while maintaining performance over time.
Implementation Method 1
a gas separating layer containing a crosslinked polyimide resin over the gas-permeable supporting layer
Implementation Method 2
introduction of crosslinked structure into a polymer compound constituting the membrane is known to be effective
Data Source
AI summary
A gas separation composite membrane, containing a gas-permeable supporting layer and a gas separating layer containing a crosslinked polyimide resin over the gas-permeable supporting layer, in which the crosslinked polyimide resin has structure in which a polyimide compound is crosslinked through a specific crosslinking chain, the specific crosslinking chain has at least one kind of linking group selected from the group consisting of —NRaC(═O)—, —NRbC(═O)O—, —CH2OCH2—, —CH2SCH2—, —OC(═O)O—, —C(═O)O−N+(Rc)3—, —SO3−N+(Rd)3— and —PO3−N+(Re)3—, and Ra, Rb, Rc, Rd and Re each independently represent a hydrogen atom or a substituent.