BCDA Semi-Alicyclic Polyimide Membrane Gas Separation
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Solution Overview
Problem
Conventional aromatic polyimide membranes for gas separation have limitations due to high production costs and insolubility in polar organic solvents, restricting their use in composite or asymmetric membrane applications, despite their high permeability and selectivity.
Innovation Solution
Development of a BCDA-based semi-alicyclic homo- or co-polyimide membrane material that enhances solubility in organic solvents, heat resistance, and gas permeability, using a polyamic acid composition with specific diamines and BCDA dianhydride, allowing for the formation of high-selective permeable composite or asymmetric membranes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional aromatic polyimide membranes are used for gas separation, then high gas permeability and selectivity are achieved, but production cost increases and solubility in polar organic solvents deteriorates
Solution Approach 1:
The patent changes the chemical structure parameters of polyimide by introducing semi-alicyclic structures (cycloaliphatic rings) instead of fully aromatic structures. This structural parameter change maintains the rigid backbone necessary for gas separation performance while improving solubility in polar organic solvents, thereby resolving the contradiction between gas separation performance and ease of manufacture
Solution Approach 2:
The patent creates composite polyimide structures by combining semi-alicyclic dianhydrides with aromatic diamines, or vice versa. This composite approach allows the material to exhibit both the solubility benefits of alicyclic structures and the thermal/stability benefits of aromatic structures, while maintaining high gas separation performance
2Reliability
If conventional aromatic polyimide membranes are used for gas separation, then high gas permeability and selectivity are achieved, but production cost increases
Solution Approach 1:
The patent employs cheaper semi-alicyclic dianhydrides (such as BCDA, DOCDA) and common aromatic diamines that can be synthesized more economically than fully aromatic polyimide monomers. This substitution reduces raw material costs while maintaining the functional performance required for gas separation applications
Solution Approach 2:
By changing the chemical composition parameters to include semi-alicyclic structures with lower synthesis costs, the patent reduces production expenses while preserving the essential gas separation capabilities through maintained chain rigidity and appropriate free volume
3Ease of manufacture
If BCDA-based semi-alicyclic polyimide is used, then solubility in polar organic solvents and heat resistance are improved, but gas permeability must be maintained at high levels
Solution Approach 1:
The patent carefully balances the proportion of semi-alicyclic to aromatic components in the polyimide structure. By optimizing this compositional parameter, the material achieves sufficient solubility in polar organic solvents for membrane fabrication while maintaining enough chain rigidity and appropriate free volume to ensure high gas permeability and separation performance
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 BCDA-based polyimide membrane exhibits superior gas separation properties for hydrogen, carbon dioxide, and oxygen, with high selectivity for hydrogen/methane, carbon dioxide/methane, and oxygen/nitrogen, enabling efficient separation and concentration of these gases with high purity, suitable for various industrial applications.
Implementation Method 1
The gas permeation characteristics of the glassy polymer membrane are affected not only by the intermolecular space, stiffness and crystalline structural properties of the membrane material
Implementation Method 2
a preparation method of the novel BCDA-based semi-alicyclic homo- or co-polyimide membrane material for gas separation
Data Source
AI summary
The present invention relates to a BCDA-based semi-alicyclic homo- or co-polyimide membrane material for gas separation and a preparation method thereof. The polyimide material prepared according to the present invention has high solubility in casting solvents, particularly in polar organic solvents, by interrupting asymmetry in the polyimide chain structure and formation of polyimide complexes compared with aromatic polyimides, and has higher heat resistance than the conventional aromatic polyimides and aliphatic polyimides, so that it is useful for the process of a high-selective permeable composite membrane or a asymmetric hollow fiber membrane used for commercial purposes, suggesting that it can be effectively used as a membrane for gas separation in various fields. In addition, the polyimide material membrane for gas separation of the present invention is useful because it has superior gas separation properties to the conventional commercialized aromatic polyimides or semi-alicyclic polyimides.