The plastic waste feedstock for chemical recycling varies immensely, from type of polymer to degree of contamination and type of format. Some chemical recyclers have developed their technology to process mixed waste, and this is often touted as a huge benefit of chemical recycling.
However, as Itero’s Chief Technology Officer Geoff Smith recently wrote in an opinion article in Sustainable Plastics, chemical recyclers working with mixed waste feedstock ‘must contend with real-world conditions’.
“Currently, many waste suppliers understand what chemical recyclers need in terms of feedstock quality,” Smith explained. “However, infrastructure is geared towards the needs of incineration. Often, we see feedstock with high fluctuations in levels of contaminants that are unimportant for incineration, but critical for chemical recycling. We are aware that this is a waste product, and we must deal with the complex realities of what consumers throw away. While systemic change is needed, change takes time, and we cannot hold off on the sustainable shifts needed today. So Itero, as chemical recyclers, must adapt to the feedstock currently available.”
Now, a partnership of two US-based companies is working to address this challenge faced by chemical recyclers. Circular Polymer Resources (CPRI), a Texas-based pyrolysis feedstock provider, and AmSpec, a testing and certification company, have signed a Memorandum of Understanding (MOU) to collaborate on the development of a comprehensive testing and certification process for waste plastic feedstock used in chemical recycling and pyrolysis oil.
“There is currently no certification process that addresses the composition and quality of plastic waste feed used in advanced recycling and the effects of those properties on the ultimate production of ethylene and propylene building blocks,” said Dr. Robert Schucker, president and CEO of CPRI. “Operators understand that contaminants such as chlorine and bromine have a detrimental effect on processing equipment but don’t have a holistic picture of how other aspects of feedstock quality affect the yield and quality of their products.”
Pyrolysis oil must be diluted with fossil-derived oils or treated to improve its quality to bring it ‘on-specification’ for steam cracking. This diminishes the yield of recycled plastic from pyrolysis or requires energy intensive processes, respectively, which has been the target of heavy criticisms from Zero Waste Europe, for example.
The new partnership plans to use existing analytical methods to fully characterise waste plastic feedstock to give all processors a comprehensive, uniformed approach to evaluate feedstocks.
CPRI will contribute its knowledge in feedstock selection and pyrolysis chemistry, whilst AmSpec will offer its testing and evaluation service of hydrocarbon streams. The companies expect the process to help standardise feed selection and processing for better yield of recycled ethylene and propylene.