What you need to know about chemical recycling of plastics
Faced with an ever-increasing volume of plastic waste and the limitations of certain traditional recycling processes, new recovery solutions are emerging. And in industrial sectors faced with complex flows that are difficult to process mechanically, we can now rely on chemical recycling.
Complementary to mechanical recycling, this method aims to transform plastic waste into a raw material of equivalent quality to the original. But what does this process actually involve? What are its advantages, limitations and practical applications? Knauf Industries reveals all about chemical plastic recycling in this article.
This article in brief
- In particular, chemical recycling enables contaminated plastics or plastics that are difficult to recycle mechanically to be processed.
- It is based on the breakdown of polymers into basic molecules.
- This technology paves the way for the production of recycled plastics of almost the same quality as virgin ones, which can be used for sensitive applications such as the food industry.
What is chemical recycling of plastics?
Chemical recycling is a material recovery process that breaks down plastic polymers into their basic chemical constituents. Unlike mechanical recycling, which relies on a physical transformation of the material (grinding, melting), chemical recycling relies on various thermal or chemical processes, such as solvolysis, pyrolysis or gasification.
These processes convert plastics into basic molecules (monomers) or intermediates such as naphtha. These products can then be used to manufacture new plastics, transformed into fuels and chemical intermediates, or integrated into existing petrochemical processes.
For manufacturers, this process is of strategic interest: it increases the overall recovery of plastics, by expanding the pool of available recycled materials. In addition to processing certain complex flows (soiled plastics, multi-layers, blends), chemical recycling also helps to improve the quality of already recyclable resins such as polypropylene (PP), in order to meet higher usage requirements.
What types of plastics are involved?
Chemical recycling is particularly relevant for technical polymers such as polyamide(PA) and PBT. These materials have more limited resources and require high mechanical performance, close to that of virgin materials, which makes chemical recycling particularly suitable.
The benefits of chemical recycling can be seen in the production of high-quality recycled materials for sensitive or technical applications, where high demands are placed on mechanical properties, purity and conformity.
This includes :
- Plastics used in demanding technical and industrial applications
- Resins requiring properties equivalent to those of virgin material
- Certain complex or specific flows, in addition to existing mechanical processes
How does the chemical recycling of plastics work?
Chemical recycling encompasses several technologies, but all are based on a common principle: the molecular transformation of matter. To achieve this, manufacturers follow a three-stage process:
1) Preparing waste
As with any industry, collection and sorting remain essential. Even if chemical recycling tolerates more heterogeneous flows, a minimum of preparation is necessary to guarantee process stability.
2) Polymer decomposition
Several processes are available:
- Pyrolysis: heating in the absence of oxygen to produce liquid or gaseous hydrocarbons
- Gasification: conversion into synthesis gas
- Depolymerization: return to the original monomers via chemical reactions
Each technology is adapted to specific types of plastics and different recovery targets.
3) Reintegrate raw materials into the production chain
Finally, these materials are reintroduced into production lines as secondary raw materials for the manufacture of new plastic products. This process makes it possible to recreate products or packaging with properties equivalent to those of virgin resin.
The advantages of this method
The chemical recycling of plastics offers several major advantages from an industrial and environmental point of view, the first of which is obviously its ability to recover complex flows. Indeed, as highlighted earlier in this article, one of the major benefits of this method is its ability to process waste that could not previously be recycled mechanically.
But it should also be noted that, by reverting to basic molecules, chemical recycling enables the production of materials with properties close to those of virgin materials, thus eliminating the degradation phenomena inherent in certain other recycling methods.
Finally, chemical recycling is a real lever for the circular economy. By allowing plastic waste to be reintroduced into production cycles, it helps to reduce dependence on fossil resources and diversify recovery solutions.
The differences between chemical and mechanical recycling
Chemical recycling and mechanical recycling respond to distinct but complementary logics:
| Critère | Recyclage mécanique | Recyclage chimique |
|---|---|---|
| Nature du procédé | Transformation physique broyage · fusion · extrusion | Transformation moléculaire décomposition chimique |
| Types de déchets traités | Flux homogènes, propres, mono-matière | Flux complexes, mélangés, souillés |
| Qualité de la matière obtenue | Possible altération des propriétés downcycling | Qualité proche du vierge selon les procédés |
It should be noted, however, that chemical recycling is generally more energy-intensive than mechanical recycling, requiring a detailed analysis of its overall environmental balance.
FAQ
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Non, ces deux méthodes sont complémentaires. Le recyclage mécanique reste prioritaire pour les flux simples et homogènes, mais le recyclage chimique permet de traiter les déchets plus complexes.
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Le recyclage chimique présente des bénéfices en matière de circularité et permet de réduire la dépendance aux ressources fossiles, mais son impact final reste dépendant de la technologie utilisée, de la source d’énergie et de l’efficacité du procédé.
As a complement to mechanical recycling, chemical recycling can really broaden the scope for waste recovery, making it possible to envisage a more global and efficient management of plastic flows.
Want to go further? Discover our other articles on reducing the carbon footprint of the plastics industry.
