What is chemical recycling / pyrolysis?

Chemical recycling today often refers to technologies that can be classed depending on the level at which they break down the plastic waste. Concretely, the technologies can be divided into 3 types:

  • Solvent-based purification. Comprises technologies that go down to the polymer stage. They are capable of decontaminating the plastic but cannot address its degradation. They work only with monostreams (PVC, PS, PE, PP).
  • Chemical depolymerisation. Chemical process which turns the plastics back into their monomers. Allows for decontamination but not addressing degradation. Only works with monostreams (PET, PU, PA, PLA, PC, PHA, PEF).
  • Thermal depolymerisation and cracking (pyrolysis and gasification) are energy-intensive processes which turn the polymers back into simpler molecules. They are capable of decontaminating polymers and, by bringing plastic back to its original building blocks, addressing the degradation of the material. These technologies can deal with more than one monomer at a time and are also capable of producing fuels. This raises the need for strict regulatory controls to prevent plastic being turned into fuel in lieu of recycling.

Gasification and pyrolysis have been tested since decades as alternatives to waste to energy incineration with very limited results due to the energy balance and the environmental impact. In general, the information available about the environmental performance of chemical recycling technologies as a whole is still extremely limited and requires further research.

In contrast with mechanical recycling, chemical recycling is an industry in its infancy and most plants in the market are in a pilot stage. The potential roll-out of such technologies at industrial scale can only be expected from 2025-2030 and this is an important factor when planning the transition to a Circular Economy and notably the decarbonisation agenda.

The conference is covering all aspects of chemical recycling / pyrolysis

Source: El Dorado of Chemical Recycling by Zero Waste Europe

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