Radiation-Cured Azide Membranes for Acid Gas Separation

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Solution Overview

Problem

Polymer membranes used for gas separation face challenges such as reduced selectivity and permeability over time due to plasticization by acid gases like CO2, requiring membranes with stable properties across varying temperatures and pressures.

Innovation Solution

Radiation-cured membranes formed from compounds with nitrogen-containing moieties and azide crosslinking agents, which provide high selectivity for acid gases and resistance to plasticization, maintaining performance over a wide range of conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional polymer membranes are used for gas separation, then initial permeability and selectivity can be achieved, but performance degrades over time due to plasticization by acid gases

Engineering Contradiction:

Improvemembrane performance stabilityVSAvoidmembrane structure stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent applies preliminary action by pre-crosslinking the polymer membrane structure before exposure to acid gases. The crosslinking is achieved through radiation curing of compounds containing nitrogen-containing moieties (urea, urethane, amide) with azide crosslinking agents, creating a stable three-dimensional network that resists plasticization during subsequent gas separation operations.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent employs composite materials by combining the base polymer matrix with crosslinking agents (azides) to create a crosslinked composite structure. This composite approach integrates the separation functionality of the polymer with the structural stability of the crosslinked network, resulting in membranes that maintain performance under harsh conditions.

Inventive Principle:

Principle #40Composite materials

2Productivity

If membrane thickness is reduced to increase permeability, then productivity improves, but mechanical strength and selectivity may be compromised

Engineering Contradiction:

Improvegas permeabilityVSAvoidmembrane mechanical strength

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

The patent utilizes thin film technology by creating crosslinked polymer membranes with optimized thickness to maximize permeability. The crosslinking provides the necessary mechanical reinforcement to maintain integrity in thin film form, enabling high productivity while preventing premature failure that would occur in uncrosslinked thin membranes.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The crosslinked composite structure provides enhanced mechanical properties that enable the use of thinner membrane sections. The three-dimensional crosslinked network acts as a reinforcing framework that maintains structural integrity even when the overall membrane thickness is reduced to improve gas permeability and productivity.

Inventive Principle:

Principle #40Composite materials

3Productivity

If operating conditions are elevated to maintain permeability, then productivity is sustained, but selectivity is lost due to plasticization

Engineering Contradiction:

Improvepermeation rateVSAvoidseparation selectivity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary anti-action by pre-crosslinking the membrane structure to prevent plasticization before it can occur during elevated temperature or pressure operation. The crosslinked network resists the plasticizing effect of acid gases, allowing the membrane to maintain both high permeability and selectivity even under harsh operating conditions that would normally degrade performance.

Inventive Principle:

Principle #9Preliminary anti-action

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 membranes exhibit enhanced selectivity and stability, allowing for efficient separation of acid gases from nonpolar gases, even at elevated temperatures and pressures, with improved resistance to plasticization compared to thermally cured counterparts.

Implementation Method 1

compounds comprising nitrogen-containing moieties that are multivalent (e.g., urea, urethane, amide, etc. that are at least divalent) can be reacted with azides using radiation energy to form membranes

Methodology Applied

Scientific EffectRadiation curing: Photopolymerisation

Implementation Method 2

different molecules can be made to permeate through selected polymers differently... the permeate mixture on the downstream side of the membrane with a greater mole fraction of one of the components

Methodology Applied

Scientific EffectPermeation: Permeation

Data Source

PatentUS9169367B2Radiation cured membranes derived from polymers that are co-reactive with azide crosslinking agent(s)

Publication Date: 2015.10.27 DDP SPECIALTY ELECTRONICS MATERIALS US LLC

AI summary

The present invention appreciates that compounds comprising nitrogen-containing moieties that are at least divalent (e.g., urea, urethane, amide, etc.) can be reacted with azides using at least radiation energy to initiate the reaction between at least a portion of the compounds and the azides to form membranes that have surprisingly high selectivities for acid gases relative to nonpolar gases such as hydrocarbons. The membranes are also resistant to CO2 plasticization and have high acid gas flux characteristics. The resultant membranes can be extremely thin (e.g., 10 micrometers or less), which promotes high permeability for the acid gas and can translate into high productivity on a scaled-up, industrial level.