Crosslinked Cellulose Gas Separation Membrane
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Solution Overview
Problem
Gas separation membranes face challenges in maintaining high gas permeability and selectivity under high temperature, high pressure, and high humidity conditions, especially when exposed to impurities like toluene, and require stabilization of performance from the early stages of use.
Innovation Solution
A gas separation membrane with a crosslinked cellulose resin having specific linking structures and containing a particular amount of organic solvent, which forms a stable gas separation layer with cellulose nanofibers and a functional polymer layer, enhancing resistance to impurities and improving folding endurance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the thickness of gas separation layer is reduced to improve gas permeability, then gas permeability is improved, but defects are generated by rubbing or folding which causes decrease in gas separation performance
Solution Approach 1:
The invention uses a composite structure consisting of a gas separation layer made from crosslinked cellulose resin and a support layer. This composite structure allows the gas separation layer to be thin for high permeability while the support layer provides mechanical strength to prevent defects from rubbing or folding.
Solution Approach 2:
The invention introduces crosslinked structures (cyclic or three-dimensional networks) into the cellulose resin, creating a more robust and flexible membrane structure that can withstand mechanical stress without generating defects, even when the gas separation layer is thin.
2Object-affected harmful factors
If crosslinked structure is introduced to suppress plasticization by impurities, then resistance to plasticization is improved, but gas separation performance decreases under high temperature, high pressure, and high humidity conditions
Solution Approach 1:
The invention carefully controls the crosslinking degree within a specific range (5-50%) to balance two opposing effects: sufficient crosslinking to resist plasticization by impurities like toluene, while limiting crosslinking to maintain gas separation performance under high temperature, high pressure, and high humidity conditions.
Solution Approach 2:
The invention creates different structural characteristics in different regions of the membrane system. The gas separation layer has controlled crosslinking for chemical stability, while the overall membrane structure maintains appropriate flexibility and porosity for gas transport under various operating conditions.
3Productivity
If gas separation layer is formed as thin layer to achieve sufficient gas permeability, then gas permeability is improved, but folding endurance decreases leading to membrane defects
Solution Approach 1:
The invention divides the membrane into two functional segments: a thin gas separation layer for high permeability and a separate support layer for mechanical strength. This segmentation allows each layer to optimize its specific function without compromising the other.
Solution Approach 2:
The invention pre-introduces crosslinked structures into the cellulose resin before forming the final membrane structure. This preliminary crosslinking enhances the flexibility and mechanical properties of the thin gas separation layer, improving its folding endurance before the membrane is put into service.
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 exhibits stable and efficient gas separation performance, maintaining high selectivity and permeability under harsh conditions and reducing the time to stabilization, while being resistant to impurities and suitable for various module forms.
Implementation Method 1
Materials formed of polymer compounds each have gas permeability specific to the constituent materials. On the basis of this property, it is possible to cause selective permeation and separation of a desired gas component by using a membrane formed of a particular polymer compound.
Implementation Method 2
In actual plants, membranes are plasticized by, for example, the influence of high-pressure conditions and impurities (for example, benzene, toluene, and xylene) that are present in natural gas, resulting in a problem of a decrease in separation selectivity. It is known that introducing a crosslinked structure or a branched structure to a polymer compound that forms a membrane is effective for suppressing this plasticization of the membrane.
Data Source
AI summary
A gas separation membrane has a gas separation layer containing a crosslinked cellulose resin. The crosslinked cellulose resin has a particular linking structure in a crosslinked structure. The gas separation layer contains an organic solvent in a particular amount.