Fluorinated Ionomer Pyrolysis for High-Yield TFE and HFP

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Solution Overview

Problem

Existing pyrolysis processes for recycling fluorinated ionomers result in low yields of tetrafluoroethylene (TFE) and hexafluoropropylene (HFP), along with the production of multiple side products, making them undesirable for recycling.

Innovation Solution

A process involving the thermal decomposition of fluorinated copolymers with sulfonic acid or carboxylic acid groups, where the copolymer is first heated to a temperature not exceeding 450°C to form a partially pyrolyzed intermediate, and then further heated to at least 550°C to produce TFE and HFP.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional pyrolysis processes are used to decompose fluorinated ionomers, then the fluorinated copolymer can be broken down, but the yield of desired fluorinated olefins (TFE and HFP) is low and multiple side products are formed

Engineering Contradiction:

Improveyield of fluorinated olefinsVSAvoidside products

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The pyrolysis process is divided into two distinct temperature stages: a first stage at 400-450°C for initial decomposition, and a second stage at 500-550°C for complete decomposition to fluorinated olefins. This segmentation allows controlled removal of functional groups at lower temperatures followed by selective production of desired products at higher temperatures, thereby improving yield and reducing unwanted side products.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The process utilizes controlled temperature parameter changes to optimize the decomposition pathway. By systematically varying the temperature parameter through two specific ranges, the process achieves complete decomposition of the fluorinated copolymer into desired olefin products while minimizing side reactions, thus resolving the contradiction between productivity and harmful byproducts.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If fluorinated ionomers are recycled through pyrolysis, then valuable fluorinated compounds can be recovered, but the process currently produces low yields and requires complex multi-step procedures

Engineering Contradiction:

Improveyield of tetrafluoroethylene and hexafluoropropyleneVSAvoidpyrolysis process steps

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The recycling process is segmented into two temperature zones within a single reactor system. The first zone (400-450°C) handles initial decomposition, while the second zone (500-550°C) completes the conversion to fluorinated olefins. This segmentation enables complete recovery of valuable compounds through a streamlined two-stage process rather than complex multi-step procedures.

Inventive Principle:

Principle #1Segmentation

3Stability of the object's composition

If high temperature pyrolysis is applied to fluorinated copolymers, then complete decomposition can be achieved, but unwanted side products are formed and yield decreases

Engineering Contradiction:

Improvecomplete decompositionVSAvoidyield of fluorinated olefins

Core Design Contradiction:

Stability of the object's compositionVSProductivity

Solution Approach 1:

Instead of applying a single high temperature, the process segments the thermal decomposition into two controlled stages. The first stage at 400-450°C initiates decomposition while preserving desired functional groups, and the second stage at 500-550°C completes the conversion to fluorinated olefins. This segmentation achieves complete decomposition with high yield by avoiding the harmful effects of excessive single-stage heating.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first temperature stage performs preliminary decomposition of the fluorinated copolymer, breaking down the polymer structure while preserving the integrity of fluorinated olefin units. This preliminary action prepares the material for the second stage, ensuring complete decomposition occurs under controlled conditions that maximize yield rather than producing unwanted side products.

Inventive Principle:

Principle #10Preliminary 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

This process achieves unexpectedly higher yields of TFE and HFP compared to other pyrolysis methods, reducing the formation of side products and making it a more viable option for recycling fluorinated ionomers.

Implementation Method 1

heating the fluorinated copolymer at a first temperature not more than 450° C. to decompose at least one of the sulfonic acid groups, carboxylic acid groups, or salts thereof to form a partially pyrolyzed intermediate

Methodology Applied

Scientific EffectThermal decomposition: Pyrolysis

Implementation Method 2

subsequently heating the partially pyrolyzed intermediate at a second temperature of at least 550° C. to produce the fluorinated olefin

Methodology Applied

Scientific EffectThermal decomposition: Pyrolysis

Data Source

PatentUS12286387B2Process of making fluoroolefins by thermal decomposition of fluorinated ionomers

Publication Date: 2025.04.29 3M INNOVATIVE PROPERTIES CO

AI summary

The process produces a fluorinated olefin from a fluorinated copolymer having at least one of sulfonic acid groups, carboxylic acid groups, or salts thereof. The process includes heating the fluorinated copolymer at a first temperature not more than 450° C. to decompose at least one of the sulfonic acid groups, carboxylic acid groups, or salts thereof to form a partially pyrolyzed intermediate and subsequently heating the partially pyrolyzed intermediate at a second temperature of at least 550° C. to produce the fluorinated olefin.