Surface-Modified CO2 Separation Membrane with Spatially Controlled Groups
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Solution Overview
Problem
Current CO2 capture technologies, such as absorption and membrane separation, face high energy consumption and costs, especially in industrial applications like the energy sector and oil and gas, and polymeric membranes are limited by their balance between permeability and selectivity, making CO2 separation from flue gas streams expensive and inefficient, particularly at low CO2 concentrations.
Innovation Solution
A CO2 selective gas separation membrane with a gas permeable support layer and a surface-modified polymer layer featuring a spatially controlled distribution of CO2 philic groups, such as amines, ethylene oxide, or hydroxyl groups, achieved through UV grafting and chemical modification, enhancing CO2 permeability and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional polymeric membranes are used for CO2 separation, then the membrane structure is simple and easy to manufacture, but the balance between permeability and selectivity is poor leading to high costs and low efficiency
Solution Approach 1:
The patent applies local quality by creating a surface-modified polymer layer with spatially controlled distribution of CO2 philic groups (such as amines, hydroxyl groups, or carboxyl groups) only at the surface of the membrane, while the bulk polymer structure remains simple and easy to manufacture. This localized modification enhances CO2 selectivity and permeability at the critical interface where gas separation occurs, resolving the contradiction between manufacturing simplicity and separation efficiency.
2Productivity
If the membrane thickness is reduced to improve CO2 separation performance, then the selectivity increases, but the mechanical strength and stability of the membrane decrease
Solution Approach 1:
The patent segments the membrane into two distinct parts: a thick, mechanically strong bulk polymer layer that provides structural stability, and a thin surface-modified layer (nanometer to micrometer thickness) that provides CO2 separation functionality. This segmentation allows the membrane to achieve high CO2 separation performance through the thin functional layer while maintaining mechanical strength through the thick support layer, resolving the contradiction between thickness reduction and stability maintenance.
3Ease of manufacture
If CO2 philic groups are randomly distributed in the polymer layer, then the membrane fabrication is simple, but the CO2 permeability and selectivity are suboptimal
Solution Approach 1:
The patent applies preliminary action by pre-modifying the polymer surface with CO2 philic groups through controlled surface modification techniques (such as plasma treatment, chemical grafting, or coating) before the gas separation process. This preliminary surface modification creates an optimized distribution of CO2 philic groups at the membrane surface, enhancing CO2 permeability and selectivity without complicating the overall membrane fabrication process, as the modification is applied only to the surface rather than requiring complex bulk polymer synthesis.
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 exhibits improved CO2 permeability and selectivity, reducing energy consumption and costs, and effectively separates CO2 from gas mixtures at low concentrations, outperforming previous polymeric membranes in industrial applications.
Implementation Method 1
Polymeric membranes separate the CO2 from a large and dilute stream (∼1-20% CO2) due to higher CO2 solubility and/or diffusion coefficient (solution-diffusion mechanism) compared to other gases such as N2 and O2 (flue gas, breathing), CH4 (natural gas, biogas), or H2 (syngas).
Implementation Method 2
The dense polymers layers may be CO2 selective because of the intrinsic chemical structure of polymer; the polymers have CO2 philic groups, such as amines, in their polymer chains
Data Source
AI summary
The present invention relates to a CO2 selective gas separation membrane and a method for preparing the gas separation membrane and the use thereof. The CO2 selective gas separation membrane comprises a gas permeable or porous support layer; and at least one gas permeable polymer layer, which is surface modified with polymer chains having CO2 philic groups, wherein the gas permeable polymer layer has a spatially controlled distribution of the CO2 philic groups on the surface thereof. The method of preparing the CO2 selective gas separation membrane, comprises the steps of: depositing at least one gas permeable polymer layer on a porous or gas permeable support layer to form a dense membrane, and surface modifying the dense membrane with polymer chains having CO2 philic groups, to obtain spatially controlled distribution of the CO2 philic groups on the surface thereof.