MIL-96 Membrane Orientation for CO2/N2 Separation
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Solution Overview
Problem
Existing metal organic framework (MOF) membranes, such as MIL-96, do not exhibit high CO2/N2 separation performance, limiting their effectiveness in industrial applications for separating CO2 from industrial exhaust gases.
Innovation Solution
A separation membrane complex is developed, comprising a porous support with a MIL-96 membrane formed through hydrothermal synthesis using seed crystals and a specific pH-controlled synthesis solution, ensuring that the intensity ratio of X-ray diffraction peaks at 2θ=5.6°, 9.0°, and 16.6° is optimized to enhance CO2 permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MIL-96 membrane is synthesized under general conditions for MOF powder synthesis, then the membrane can be formed, but the CO2/N2 separation performance is insufficient
Solution Approach 1:
The patent applies parameter changes by precisely controlling the pH of the synthesis solution to a specific range (1.90-2.51) and optimizing the synthesis temperature (100-200°C) and time (1-48 hours). These parameter modifications transform the general MOF synthesis process into a controlled process that produces MIL-96 membrane with optimized pore structure and orientation for high CO2/N2 separation performance (separation factor ≥2.0).
Solution Approach 2:
The patent employs preliminary action by first forming seed crystals with specific size (180-220 nm average particle diameter) before the main synthesis process. These pre-formed seed crystals serve as templates that guide the growth of MIL-96 membrane with desired crystal orientation and pore distribution, ensuring high CO2 permeability and separation performance from the outset.
2Reliability
If c-axis oriented MIL-96 membrane is synthesized by adding N-Methylformamide or formamide, then the membrane structure is oriented, but the CO2/N2 separation performance remains insufficient
Solution Approach 1:
The patent extracts and eliminates the need for additional orientation additives (N-Methylformamide or formamide) that were previously used to achieve c-axis orientation. Instead, it achieves both crystal orientation and high CO2/N2 separation performance through pH-controlled synthesis (pH 1.90-2.51) and seed crystal templating, simplifying the synthesis solution composition while maintaining or improving separation performance.
Solution Approach 2:
The patent changes the critical synthesis parameter from additive-based orientation control to pH-based control. By maintaining the synthesis solution pH within 1.90-2.51, the patent achieves spontaneous formation of properly oriented MIL-96 crystals with optimal pore structures for CO2 separation, eliminating the need for complex additive systems.
3Manufacturing precision
If seed crystals with specific size (180-220 nm) are used, then the membrane growth is controlled, but the manufacturing precision requirements increase
Solution Approach 1:
The patent establishes a specific parameter range for seed crystal size (180-220 nm average particle diameter) that balances manufacturing feasibility with performance requirements. This parameter specification allows for controlled membrane growth and proper crystal orientation during synthesis, achieving high CO2/N2 separation performance while maintaining reasonable manufacturing precision through standardized seed crystal preparation protocols.
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 a CO2/N2 ideal separation factor of at least 2, significantly improving CO2/N2 separation performance by orienting planes with larger pore diameters to the front surface, facilitating easier CO2 permeation.
Implementation Method 1
forming a separation membrane on the support by immersing the support in a synthesis solution which contains an Al source and trimesic acid and has a pH of 1.90 to 2.51 and performing hydrothermal synthesis to grow metal organic framework MIL-96 from the seed crystals
Implementation Method 2
in an X-ray diffraction pattern obtained by X-ray irradiation onto a surface of the separation membrane
Implementation Method 3
an intensity of a peak existing in the vicinity of 2θ=5.6° is not higher than 0.15 times an intensity of a peak existing in the vicinity of 2θ=9.0° and not higher than 0.4 times an intensity of a peak existing in the vicinity of 2θ=16.6°
Implementation Method 4
the membrane achieves a CO2/N2 ideal separation factor of at least 2, significantly improving CO2/N2 separation performance by orienting planes with larger pore diameters to the front surface, facilitating easier CO2 permeation
Data Source
AI summary
A separation membrane complex includes a porous support and a separation membrane which is formed on the support and composed of metal organic framework MIL-96. In an X-ray diffraction pattern obtained by X-ray irradiation onto a surface of the separation membrane, an intensity of a peak existing in the vicinity of 2θ=5.6° is not higher than 0.15 times an intensity of a peak existing in the vicinity of 2θ=9.0° and not higher than 0.4 times an intensity of a peak existing in the vicinity of 2θ=16.6°.