Fluorinated Copolymer Membranes for Gas Separation
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Solution Overview
Problem
Current gas separation membranes, such as those made from perfluoropolymers, face challenges in achieving high selectivity and flux while maintaining chemical resistance, particularly for gas pairs like H2/CH4, He/CH4, CO2/CH4, and N2/CH4, and lack adequate performance for industrial applications.
Innovation Solution
A process utilizing a copolymer membrane with a selective layer formed from a combination of perfluorodioxolane and perfluorinated or partially fluorinated dioxane monomers, which balances crystalline and amorphous phases to enhance gas separation properties, including higher selectivity and flux for gases like hydrogen, helium, carbon dioxide, and nitrogen from methane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If perfluoropolymer membranes (Hyflon AD, Teflon AF) are used, then chemical resistance and stability are improved, but gas selectivity for H2/CH4, He/CH4, CO2/CH4, and N2/CH4 pairs deteriorates
Solution Approach 1:
The patent modifies the chemical composition parameters of perfluoropolymer membranes by incorporating specific fluorinated cyclic monomers (such as perfluorodioxole and perfluorodioxane units) into the polymer chain. This changes the molecular structure parameters including free volume, chain rigidity, and intermolecular interactions, thereby improving gas selectivity while preserving the inherent chemical resistance of perfluoropolymers
Solution Approach 2:
The patent creates composite perfluoropolymer structures by combining different fluorinated monomer units (TFE, PFO, and cyclic monomers like perfluorodioxole and perfluorodioxane) into copolymer systems. This composite approach allows optimization of both chemical stability and gas separation performance by leveraging the complementary properties of each monomer component
2Ease of manufacture
If copolymerization with TFE is performed, then processability and size selectivity are improved, but overall gas permeability deteriorates
Solution Approach 1:
The patent adjusts the compositional parameters of the copolymer by controlling the ratio of TFE to fluorinated cyclic monomers, and modifies the molecular structure parameters through the introduction of cyclic units that create specific free volume characteristics. This balances the competing requirements of processability (improved by TFE) and gas permeability (maintained by cyclic monomer structures)
3Quantity of substance
If glassy polymer structures with cyclic units are used, then gas permeability is improved, but plasticization resistance deteriorates
Solution Approach 1:
The patent modifies the molecular structure parameters by incorporating rigid fluorinated cyclic monomer units (perfluorodioxole and perfluorodoxane) into the polymer chain. These cyclic structures create a rigid, glassy polymer matrix with controlled free volume that enhances both gas permeability through favorable free volume characteristics and plasticization resistance through increased chain rigidity and reduced chain mobility
Solution Approach 2:
The patent creates a composite polymer structure combining flexible TFE units with rigid fluorinated cyclic monomer units. This composite architecture provides the flexibility and processability needed for membrane fabrication while the rigid cyclic units provide the structural integrity and plasticization resistance required for reliable operation
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 copolymer membrane achieves improved selectivity and flux for gas separations, making it suitable for industrial applications such as natural gas processing, carbon capture, and helium recovery, while maintaining chemical resistance and stability.
Implementation Method 1
passing the gas mixture across a separation membrane having a feed side and a permeate side
Implementation Method 2
providing a driving force for transmembrane permeation
Data Source
AI summary
A process for separating components of a gas mixture using gas-separation copolymer membranes. These membranes use a selective layer made from copolymers of partially fluorinated or perfluorinated dioxolane monomers and a second monomer, such as dioxane or a partially fluorinated dioxolane. The resulting membranes have superior selectivity performance for gas pairs of interest while maintaining fast gas permeance compared to membranes prepared using conventional perfluoropolymers, such as Teflon® AF, Hyflon® AD, and Cytop®.