PVDC Extrusion and Pyrolysis for Microcapillary CMS Membranes
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Solution Overview
Problem
Existing microcapillary carbon molecular sieve membranes face challenges with fragility and difficulty in forming extruded structures, which affect their gas separation efficiency and stability.
Innovation Solution
A process involving extrusion of a polyvinylidene chloride polymer to form a microcapillary film, followed by pre-treatment and pyrolysis, results in a microcapillary carbon molecular sieve membrane with controlled micropore size and structure, enabling effective gas separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hollow fiber geometry is used to provide large surface area, then gas separation efficiency is improved, but membrane fragility worsens due to curved seal surfaces and small seal voids
Solution Approach 1:
The patent transitions from hollow fiber geometry (one-dimensional tubular structure) to microcapillary film geometry (two-dimensional planar structure with through-flow channels). This dimensional change allows the membrane to maintain large surface area for gas separation while eliminating the fragility issues associated with curved seal surfaces in hollow fibers. The microcapillary films provide a robust planar structure that is easier to seal and more mechanically stable.
2Area of stationary object
If conventional CMS membranes are formed into hollow fiber geometry, then surface area is increased, but carbon-epoxy seal quality deteriorates
Solution Approach 1:
The patent moves from three-dimensional hollow fiber geometry to two-dimensional microcapillary film geometry. This dimensional transition provides a planar seal surface that is superior to curved hollow fiber seals. The flat microcapillary film structure allows for better seal contact, reduced seal voids, and improved carbon-epoxy interfacial adhesion while maintaining high surface area through the microcapillary through-flow channels.
3Strength
If microcapillary membranes are embedded in films to create hybrid geometry, then self-support is improved, but manufacturing complexity increases
Solution Approach 1:
The patent segments the membrane structure into distinct functional components: the microcapillary film provides the self-supporting framework and gas separation function, while the carrier film provides mechanical strength and stability. This segmentation allows each component to perform its specific function optimally. The microcapillary film can be independently manufactured with controlled micropore size and then combined with the carrier film, simplifying the manufacturing process compared to creating self-supported hollow fiber structures.
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 process produces a robust microcapillary CMS membrane with improved gas throughput and selectivity for gas pairs with molecular diameters between 3 Å to 5 Å, suitable for various gas separation applications.
Implementation Method 1
pyrolizing the pre-treated polymeric microcapillary film at a temperature from 500° C. to 1,000° C. for a time from 15 minutes to 5 hours to form the microcapillary carbon molecular sieve membrane
Implementation Method 2
extruding a polyvinylidene chloride (PVDC) polymer to a thickness from 10 μm to 1,000 μm to form an extruded polymeric microcapillary film
Data Source
AI summary
A process for preparing a microcapillary carbon molecular sieve membrane may include extruding a polyvinylidene chloride polymer to a thickness from 10 μm to 1,000 μm to form an extruded polymeric microcapillary film, wherein the extruded polymeric microcapillary film comprises a first end, a second end, and one or more microcapillaries extending from the first end to the second end; pre-treating the extruded polymeric microcapillary film at a temperature from 100° C. to 200° C. for a time from 1 hour to 48 hours to form a pre-treated polymeric microcapillary film; and pyrolizing the pre-treated polymeric microcapillary film at a temperature from 200° C. to 1,500° C. for a time from 15 minutes to 5 hours to form the microcapillary carbon molecular sieve membrane.