Poly(benzoxazole-imide) Gas Separation Membrane with Siloxane Layer

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Solution Overview

Problem

Gas separation membranes face challenges in maintaining high gas permeability and selectivity, especially under high-pressure and high-humidity conditions, and are prone to plasticization by impurities like toluene, requiring improved mechanical strength and resistance.

Innovation Solution

A gas separation membrane with a poly(benzoxazole-imide) compound is developed, featuring specific structural units and a siloxane compound layer, which provides enhanced mechanical strength, resistance to impurities, and improved folding endurance through heat treatment and siloxane layer formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a thin dense layer is formed to achieve high gas permeability and separation selectivity, then gas separation performance is improved, but mechanical strength decreases

Engineering Contradiction:

Improvegas separation performanceVSAvoidmechanical strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The membrane is divided into two functional layers: a thin dense layer (0.1-10 μm) for gas separation and a thick porous support layer for mechanical strength. This segmentation allows each layer to optimize its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses a composite membrane structure combining a polyimide-based dense layer with a porous support layer. The composite structure integrates the high selectivity of the dense polymer layer with the mechanical robustness of the support layer, resolving the contradiction between thin-layer performance and structural strength.

Inventive Principle:

Principle #40Composite materials

2Productivity

If high-pressure conditions are applied to increase gas throughput, then productivity is improved, but membrane defects are generated

Engineering Contradiction:

Improvegas throughputVSAvoidmembrane integrity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The porous support layer is designed beforehand to provide mechanical reinforcement that cushions against high-pressure stress. This pre-established structural support prevents membrane defects from forming during high-pressure operation, allowing sustained high throughput without compromising integrity.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The composite structure with the porous support layer provides the mechanical strength needed to withstand high-pressure conditions without generating defects, enabling high productivity while maintaining membrane integrity.

Inventive Principle:

Principle #40Composite materials

3Ease of operation

If impurities like toluene are present in the gas stream, then gas processing is simplified, but plasticization occurs and separation selectivity decreases

Engineering Contradiction:

Improvegas processing simplicityVSAvoidseparation selectivity

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The invention modifies the chemical parameters of the polyimide membrane by incorporating specific aromatic rings and imide groups, which change the membrane's interaction parameters with impurities like toluene. This reduces plasticization effects while maintaining the ability to process gas streams containing these impurities.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The composite membrane structure with the porous support layer provides resistance to plasticization by impurities, maintaining separation selectivity even when processing gas streams containing substances like toluene, thus preserving reliability without complicating operation.

Inventive Principle:

Principle #40Composite materials

4Area of stationary object

If the membrane is folded in a spiral manner to increase surface area density, then membrane surface area is improved, but folding endurance is required

Engineering Contradiction:

Improvemembrane surface areaVSAvoidfolding endurance

Core Design Contradiction:

Area of stationary objectVSStrength

Solution Approach 1:

The membrane is configured in a spiral arrangement, transitioning from a two-dimensional flat structure to a three-dimensional rolled structure. This dimensional change increases the effective surface area within a compact module volume while the porous support layer provides the structural integrity needed for repeated folding and unfolding.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The composite structure with the porous support layer provides the mechanical strength and flexibility required for folding endurance, enabling the membrane to be configured in spiral arrangements that maximize surface area while withstanding the mechanical stresses of installation and operation.

Inventive Principle:

Principle #40Composite materials

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 achieves high gas permeability and selectivity, maintaining performance under high-pressure and high-humidity conditions while resisting plasticization by impurities, and can be produced at a high yield.

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.

Methodology Applied

Scientific EffectSelective permeation: Permeation

Implementation Method 2

Methodology Applied

Scientific EffectMechanical strength enhancement:

Implementation Method 3

Methodology Applied

Scientific EffectHeat treatment: Heat Treatment

Data Source

PatentUS10478786B2Gas separation membrane, gas separation module, gas separation apparatus, and gas separation method

Publication Date: 2019.11.19 FUJIFILM CORP

AI summary

A gas separation membrane has a gas separation layer containing a poly(benzoxazole-imide) compound in which the poly(benzoxazole-imide) compound having structural units represented by General formulae (I) and (II), or structural units represented by General formulae (I), (II) and (III) satisfies a specific molar quantity condition.In the formulae, X and Y each represent a single bond or a specific divalent linking group; L represents a specific divalent linking group including a phenylene group; and R represents a specific group. A gas separation module and a gas separation method use the gas separation membrane. A gas separation apparatus includes the gas separation module.