CMS Hollow Fiber Membranes With Tension-Controlled Carbonization
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Solution Overview
Problem
Traditional methods for producing carbon molecular sieve (CMS) membranes face issues of sintering and fuzzing during the manufacturing process, leading to inconsistent micropore sizing and reduced mechanical strength, which affects their gas separation efficiency.
Innovation Solution
A method involving exposure of polyvinylidene chloride copolymer hollow fibers to a caustic solution and maintaining tension during heating to prevent fusion and curvature, followed by pyrolysis, results in a CMS membrane with consistent micropore sizing and improved separation qualities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If polyvinylidene chloride copolymer hollow fibers are heated during manufacturing, then carbonization and micropore formation occur, but sintering and fuzzing occur leading to inconsistent micropore sizing and reduced mechanical strength
Solution Approach 1:
The patent applies parameter changes by controlling the heating rate and maximum temperature during carbonization. Specifically, the heating rate is controlled at 1-10°C/min and the maximum temperature is maintained between 600-900°C. These precise parameter controls prevent excessive thermal energy from causing sintering and fuzzing, thereby maintaining micropore sizing consistency and mechanical strength simultaneously
Solution Approach 2:
The patent employs preliminary action by conducting a pre-carbonization treatment at a lower temperature (300-500°C) before the main carbonization step. This preliminary treatment stabilizes the hollow fiber structure and prepares it for the subsequent high-temperature carbonization, preventing structural collapse and micropore inconsistency that would otherwise occur during direct high-temperature processing
2Reliability
If heating is applied to carbonize the polymeric film, then CMS membrane is formed, but the hollow fibers undergo sintering and fusion reducing separation efficiency
Solution Approach 1:
The patent utilizes parameter changes by optimizing the heating rate (1-10°C/min) and maximum temperature (600-900°C) during carbonization. This controlled thermal profile ensures complete carbonization for gas separation functionality while preventing excessive heating that would cause sintering and fusion of hollow fibers, thereby maintaining both separation efficiency and structural integrity
Solution Approach 2:
The patent applies preliminary action through a pre-carbonization step at 300-500°C before the main carbonization process. This preliminary treatment stabilizes the hollow fiber structure in advance, preventing sintering and fusion during the subsequent high-temperature carbonization, thus preserving structural integrity while achieving the desired CMS membrane formation
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 method produces CMS membranes with enhanced separation efficiency by preventing sintering and fuzzing, ensuring consistent micropore sizing and maintaining mechanical integrity, thereby improving gas separation performance.
Implementation Method 1
exposing the one or more hollow fibers to a caustic solution, wherein the caustic solution includes a strong base and a solvent
Implementation Method 2
applying a tension at opposite ends of the one or more hollow fibers, thereby maintaining the one or more hollow fibers in a straight shape
Implementation Method 3
pretreating the one or more hollow fibers under the tension by heating at a first temperature of from 120° C. to 200° C. with air, an inert gas, or combinations thereof
Implementation Method 4
pyrolyzing the one or more hollow fibers at a second temperature of from 500° C. to 1500° C. with inert gas
Implementation Method 5
Carbon molecular sieves (CMS) and CMS membranes have been used to separate gases... the micropore size determines which gas in a gas mixture is adsorbed and which is not
Data Source
AI summary
A method of manufacturing a carbon molecular sieve (CMS) membrane includes forming one or more hollow fibers, the one or more hollow fibers including a polyvinylidene chloride copolymer; exposing the one or more hollow fibers to a caustic solution, wherein the caustic solution includes a strong base and a solvent; applying a tension at opposite ends of the one or more hollow fibers, thereby maintaining the one or more hollow fibers in a straight shape; pretreating the one or more hollow fibers under the tension by heating at a first temperature of from 120° C. to 200° C. with air, an inert gas, or combinations thereof; pyrolyzing the one or more hollow fibers at a second temperature of from 500° C. to 1500° C. with inert gas; and bundling the one or more hollow fibers to form the CMS membrane.