Carbon membrane for fluid separation and method for manufacturing same
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Solution Overview
Problem
Hollow fiber carbon membranes for fluid separation are prone to breakage during vacuum desorption and fluid permeation due to dimensional changes caused by water vapor adsorption and elongation, leading to gas leakage and impaired separation performance.
Innovation Solution
A carbon membrane structure comprising a porous carbon support with an Raman spectrum R s value of 1.0 or less and a dense carbon layer with an R m value between 1.1 and 3.0, formed by specific carbonization processes, to stabilize the membrane against dimensional changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hollow fiber carbon membranes are used for fluid separation, then manufacturing cost is reduced and productivity is improved, but the membranes are prone to breakage during vacuum desorption and fluid permeation due to dimensional changes
Solution Approach 1:
The patent applies parameter changes by controlling the carbonization temperature (500-900°C) and duration to achieve optimal graphitization degree of the carbon membrane. By adjusting these parameters, the membrane attains dimensional stability while maintaining flexibility, preventing breakage during vacuum desorption and fluid permeation. The carbonization process transforms the precursor resin into a stable carbon structure with controlled physical properties.
Solution Approach 2:
The patent uses composite materials by combining a porous support layer with a carbon membrane layer formed from carbonizable resin. This composite structure provides both mechanical strength from the support and separation functionality from the carbon membrane. The combination achieves dimensional stability while maintaining the benefits of hollow fiber configuration for high productivity.
2Reliability
If the carbon membrane is made more flexible to prevent breakage, then reliability is improved, but separation performance may deteriorate
Solution Approach 1:
The patent applies local quality by creating different structural zones within the carbon membrane. The carbonization process produces regions with varying graphitization degrees, where the bulk provides flexibility and the selective layer maintains separation performance. This gradient structure allows the membrane to be flexible overall while preserving local separation functionality.
Solution Approach 2:
The patent uses parameter changes by controlling carbonization temperature and time to achieve optimal balance between flexibility and separation performance. At 500-900°C, the carbon membrane develops sufficient crystallinity for separation while maintaining adequate flexibility. The process parameters are optimized to prevent over-carbonization which would make the membrane too brittle.
3Ease of manufacture
If water vapor adsorption causes dimensional changes, then the membrane structure is simple and easy to manufacture, but breakage occurs during vacuum desorption and fluid permeation
Solution Approach 1:
The patent applies parameter changes by optimizing the carbonization temperature range (500-900°C) to achieve dimensional stability without complex additional processing steps. Within this temperature range, the carbon membrane undergoes sufficient structural transformation to resist water vapor-induced dimensional changes, maintaining reliability while keeping the manufacturing process simple and straightforward.
Solution Approach 2:
The patent addresses thermal and hygroscopic expansion by controlling the carbonization process to create a carbon structure with reduced sensitivity to environmental changes. The carbonized membrane exhibits minimal dimensional change upon water vapor adsorption compared to the precursor state, preventing breakage during vacuum desorption and fluid permeation while maintaining manufacturing simplicity.
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 proposed structure effectively suppresses breakage during vacuum desorption and fluid permeation, maintaining separation performance and preventing fluid leakage.
Implementation Method 1
carbonizing a molded body containing a resin serving as a precursor of a porous carbon support at a carbonization temperature of 900°C or more and 1,500°C or less to produce a porous carbon support
Implementation Method 2
carbonizing the carbonizable resin layer to form a dense carbon layer at a carbonization temperature of 500°C or more and 850°C or less
Implementation Method 3
the hollow fiber carbon membrane may shrink in the course of desorption of water vapor adsorbed onto the carbon membrane and the support
Data Source
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AI summary
The present invention provides a carbon membrane for fluid separation that can suppress the breakage of a carbon membrane installed in a separation module during a vacuum desorption step before permeation of a fluid or during permeation of a fluid. The present invention provides a carbon membrane for fluid separation including a porous carbon support and a dense carbon layer provided on the porous carbon support, wherein the porous carbon support has an Rs value of 1.0 or less, where the Rs value is an R value (peak intensity of D-band (1360 cm-1)/peak intensity of G-band (1580 cm-1)) calculated from a Raman spectrum.