Crosslinked Polyether-b-amide Membranes for Sour Gas Separation
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Solution Overview
Problem
Current polymeric membranes for natural gas separation face challenges such as low CO2 permeability and selectivity, as well as susceptibility to plasticization, which limits their effectiveness in removing corrosive gases like CO2 and H2S from natural gas.
Innovation Solution
Development of crosslinked membranes composed of a poly(ether-b-amide) copolymer and acrylate-terminated poly(ethylene glycol), which are formed through a process involving dissolution, casting, and photopolymerization to create interpenetrating polymer networks, enhancing mechanical and thermal stability and CO2 permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If glassy polymers such as cellulose acetate are used for CO2 separation, then high pure gas CO2/CH4 selectivity is achieved, but CO2 permeability becomes very low
Solution Approach 1:
The patent uses a composite polymer system combining poly(ether-b-amide) with acrylate-terminated poly(ethylene glycol) that has been crosslinked. This composite structure allows the membrane to achieve both high CO2/CH4 selectivity (around 30-40) and improved CO2 permeability (above 12 Barrer), resolving the traditional trade-off between these two properties in glassy polymers
Solution Approach 2:
The patent modifies the polymer structure by introducing crosslinks through photopolymerization of acrylate-terminated PEG chains. This parameter change (from linear to crosslinked structure) enhances the membrane's mechanical stability and resistance to plasticization while maintaining gas separation performance and improving CO2 permeability
2Ease of manufacture
If polymeric membranes are used for gas separation, then manufacturability and low material costs are achieved, but physical aging and plasticization occur
Solution Approach 1:
The patent incorporates crosslinkable functional groups (acrylate terminals) into the PEG chains before membrane formation. The crosslinking is then induced by UV irradiation after the membrane is formed, creating a stable crosslinked network that prevents future plasticization and physical aging while maintaining the ease of membrane manufacturing
Solution Approach 2:
The patent changes the physical state of the polymer chains from mobile and flexible to a crosslinked network structure. This parameter change fundamentally alters the membrane's resistance to plasticization by CO2 and other gases, while the crosslinking process itself is simple and does not complicate manufacturing
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 crosslinked membranes exhibit improved CO2 permeability, resistance to plasticization, and increased CO2/CH4 selectivity, maintaining stable performance under varying pressures and reducing weight loss, thus addressing the limitations of existing membranes.
Implementation Method 1
exposing the film to a photoactivator to form the gas separation membrane
Data Source
AI summary
A method of separating gas and a method of making a gas separation membrane. The method of separating gas includes flowing a gas stream through a membrane, in which the membrane comprises a crosslinked mixture of a poly(ether-b-amide) copolymer and an acrylate-terminated poly(ethylene glycol) according to formula (I) or formula (II); and separating the gas stream via the membrane.In formulas (I) and (II), each n is of from 2 to 30; and each R is independently —H or —CH3.