Cross-linked Polymeric Membrane for Aromatic Separation

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Solution Overview

Problem

Current polymeric membranes used in separation processes, such as pervaporation and perstraction, face challenges with limited flux and selectivity due to mechanical instability and structural limitations, particularly when thin films are used to enhance performance, which can lead to voids and inconsistencies.

Innovation Solution

A polymeric membrane composition comprising a dianhydride, a diamine, and a cross-linking agent, specifically utilizing dihydroxy end-functionalized polymers and chemical cross-linking at low temperatures to create a membrane with improved mechanical stability and enhanced flux and selectivity, while maintaining a high concentration of active soft segments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If thin films are used to enhance flux characteristics, then flux rate is improved, but mechanical stability deteriorates due to voids and inconsistencies

Engineering Contradiction:

Improveflux rateVSAvoidmechanical stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the membrane by incorporating specific polyurethane polymers with controlled molecular weights and functionalities, along with crosslinking agents, to achieve optimal balance between flux rate and mechanical stability without requiring extremely thin film configurations

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite membrane system by combining polyurethane polymer matrices with crosslinking agents to form a mechanically reinforced structure that maintains high flux characteristics while improving mechanical stability and reducing void formation

Inventive Principle:

Principle #40Composite materials

2Strength

If thermal cross-linking is used to provide mechanical strength, then structural integrity is improved, but flux and selectivity characteristics deteriorate

Engineering Contradiction:

Improvestructural integrityVSAvoidflux and selectivity

Core Design Contradiction:

StrengthVSProductivity

Solution Approach 1:

The patent modifies the crosslinking process parameters by using alternative crosslinking mechanisms and controlling the degree of crosslinking to maintain structural integrity while preserving the porous structure and chemical properties necessary for high flux and selectivity performance

Inventive Principle:

Principle #35Parameter changes

3Reliability

If copolymer chains with hard segments are used to provide mechanical strength, then mechanical stability is improved, but permeability deteriorates

Engineering Contradiction:

Improvemechanical stabilityVSAvoidpermeability

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies local quality by creating distinct regions within the membrane structure where soft segments provide permeability pathways and hard segments provide mechanical reinforcement, optimizing both permeability and mechanical stability through spatial differentiation of functional properties

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent develops a composite copolymer structure combining soft segments for permeability and hard segments for mechanical strength, where the synergistic interaction between different polymer segments achieves both high mechanical stability and maintained permeability

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 resulting membrane exhibits superior flux rates and selectivity, with a higher ratio of aliphatic C—H soft segments to aromatic C—H hard segments, providing improved separation performance and mechanical stability, making it suitable for commercial-scale operations.

Implementation Method 1

chemical cross-linking at low temperatures to create a membrane with improved mechanical stability

Methodology Applied

Scientific EffectChemical cross-linking: Chemical Bonding

Implementation Method 2

a desired feed component, e.g., an aromatic component, of a mixed liquid feed is preferentially absorbed by the membrane

Methodology Applied

Scientific EffectPreferential absorption: Absorption (physical)

Implementation Method 3

the adsorbed component migrates through the membrane and is removed as a vapor from the opposite side of the membrane via a solution-diffusion mechanism

Methodology Applied

Scientific EffectSolution-diffusion mechanism: Diffusion

Implementation Method 4

the driving mechanism for the separation of the stream into separate products is provided by a pressure or a concentration gradient exerted across the membrane

Methodology Applied

Scientific EffectPressure gradient: Pressure Gradient

Implementation Method 5

A concentration gradient driving force is therefore established to selectively pass the desired components through the membrane from its upstream side to its downstream side

Methodology Applied

Scientific EffectConcentration gradient: Diffusion

Data Source

PatentUS8083946B2Chemically cross-linked polymeric membranes and method of use

Publication Date: 2011.12.27 EXXONMOBIL TECHNOLOGY & ENGINEERING CO

AI summary

This invention relates to the fabrication of a polymeric membrane and a process for utilizing the polymeric membrane for separating components of a feedstream. More particularly, but not by way of limitation, this invention relates to the fabrication of a polymeric membrane and a process for utilizing the polymeric membrane in the separation of aromatics from a hydrocarbon based feedstream. The membranes of the present invention possess low soft segment glass transition temperatures and improved separation characteristics.