Separation Membrane Complex with End-Portion Defects for Gas Permeation
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Solution Overview
Problem
Current separation membrane complexes, particularly monolith-type systems, face limitations in gas separation performance due to low permeation efficiency in central cells and susceptibility to cracks at longitudinal end portions, which restricts the improvement of mixed gas separation efficiency.
Innovation Solution
A separation membrane complex with a porous support and a zeolite membrane, where the average CF4 permeance of the membranous end portions is 5 times or more and 100 times or less of the central portion, and a sealer covering the support to enhance gas flow and reduce leakage, is developed. The membrane is produced by depositing seed crystals on the support, followed by hydrothermal synthesis to form a zeolite membrane with intentionally formed defects at the end portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a monolith-type separation membrane complex is used with sealers at longitudinal end portions, then gas leakage is reduced, but cracks occur in the separation membrane near the sealers reducing reliability
Solution Approach 1:
The patent applies local quality by creating intentional defects only at the end portions of the separation membrane (within 1/10 of the longitudinal length from edges) while maintaining integrity in the central portion. This localized defect creation allows the membrane to have different properties in different regions, enabling sweep gas flow at ends without compromising overall reliability.
Solution Approach 2:
The patent converts the harmful effect of potential cracks into a beneficial feature by intentionally creating controlled defects at the end portions. These defects serve as sweep gas pathways that improve separation performance, transforming what would normally be a reliability issue into a performance enhancement mechanism.
2Productivity
If sweep gas is flowed into the space outside the column-like porous support, then permeation acceleration is achieved in cells near the sweep gas flow space, but cells distant from this space (e.g., central cells) do not experience significant permeation improvement
Solution Approach 1:
The patent segments the membrane system into three distinct regions: defect-containing end portions (within 1/10 of longitudinal length), transition zones, and an intact central portion. This segmentation allows different regions to serve different functions, with end portions providing sweep gas pathways and the central portion maintaining selective separation, thereby achieving uniform permeation improvement across all cells.
Solution Approach 2:
The patent introduces a new dimensional approach by creating defects at the longitudinal ends of the membrane, which provides alternative pathways for gas flow in the longitudinal dimension. This complements the radial flow through the membrane, creating a three-dimensional flow pattern that ensures all cells, including central ones, benefit from sweep gas effects.
3Reliability
If the separation membrane is made denser to reduce defects, then separation selectivity improves, but permeation rate decreases
Solution Approach 1:
The patent applies local quality by creating defects only at the end portions (within 1/10 of longitudinal length from edges) while maintaining membrane integrity in the central portion. This localized approach allows the bulk of the membrane to maintain high selectivity while the end portions provide high-permeability pathways for sweep gas, achieving both selectivity and productivity.
Solution Approach 2:
The patent uses the end portion defects as intermediary pathways that mediate between the high-selectivity central membrane and the sweep gas flow. These defect regions act as transition zones that facilitate gas transport without compromising the selective separation function of the main membrane body.
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
This configuration significantly enhances the separation performance by increasing the permeance ratio of the end portions to the central portion, improving CO2 recovery rates and maintaining membrane denseness, thereby accelerating gas permeation and reducing defects.
Implementation Method 1
the specific gas (hereinafter, referred to as the 'to-be-permeated gas') in the mixed gas permeates the gas separation membrane structure and flows to the other space
Implementation Method 2
a sweep gas is flowed into the space on the permeate side so as to lower the partial pressure of the to-be-permeated gas in the space on the permeate side and to accelerate the permeation of the to-be-permeated gas
Implementation Method 3
a column-like porous support and a separation membrane, the porous support having a plurality of through holes (i.e., cells) each extending in the longitudinal direction
Data Source
AI summary
A separation membrane complex includes a porous support and a separation membrane formed on the support. In the separation membrane complex, average CF4 permeance of one membranous end portion is 5 times or more and 100 times or less of average CF4 permeance of a membranous central portion, the one membranous end portion being a portion of the separation membrane that is within a range of one-tenth of the longitudinal length of the separation membrane from one longitudinal edge of the separation membrane, the membranous central portion being a portion of the separation membrane excluding the membranous end portions on both longitudinal sides of the separation membrane.