Eni’s chemical subsidiary Versalis plans to build its first industrial-scale HOOP® chemical recycling plant at Priolo in Sicily. The facility is designed to process 40,000 tonnes of mixed plastic packaging waste per year and produce around 32,000 tonnes of pyrolysis oil.
HOOP® was developed by Versalis together with Italian engineering company S.R.S. (Servizi di Ricerche e Sviluppo). The process combines a high-performance pyrolysis reactor with polymer analysis and process optimisation using artificial intelligence. Before Priolo, Versalis commissioned a 6,000-tonne-per-year demonstration plant in Mantua in 2025 to validate the technology at larger scale.
The resulting recycled oil can be upgraded and used as petrochemical feedstock, ultimately allowing new polymers to be produced. In industrial practice, plastic-derived pyrolysis oil can be blended with conventional feedstocks such as naphtha before steam cracking.
The Risks
Feedstock quality is critical. Mixed plastic waste can introduce chlorine, nitrogen, oxygen, metals and other contaminants into pyrolysis oil. Research has found some contaminants at concentrations substantially above normal steam-cracker specifications, meaning sorting, pretreatment and upgrading can be necessary.
Purification is not trivial. Distillation can remove much of the metallic contamination, but studies show chlorine, nitrogen and oxygen can remain above desirable limits. Further treatment therefore adds equipment, energy consumption and operating cost.
Coke and fouling are another concern. Experiments comparing pyrolysis-oil/naphtha blends with conventional naphtha found increased coke formation, particularly with more contaminated pyrolysis oils. Coke accumulation can increase maintenance requirements and eventually reduce operating availability.
There is also scale-up risk. Priolo will process almost seven times the annual volume of the Mantua demonstration unit. Commercial reliability, continuous operation and maintenance performance still have to be demonstrated at this scale.
The economics are another question. Pyrolysis requires waste preparation, high-temperature processing, purification and downstream petrochemical processing. Its costs therefore have to compete with both fossil feedstocks and mechanical recycling.
Finally comes the mass-balance and yield question. Eni expects roughly 32,000 tonnes of pyrolysis oil from 40,000 tonnes of input, meaning the first processing step already does not convert all incoming material into oil. Further upgrading and cracking create additional products and losses.
The most important number may therefore not be the plant’s 40,000-tonne input capacity, but how many tonnes ultimately return to the market as new plastic.
Source
https://www.versalis.eni.com/en-IT/news/press-release/2025/hoop-demo-plant-at-mantua.html
https://www.sciencedirect.com/science/article/abs/pii/S0378382021003714
https://www.sciencedirect.com/science/article/pii/S0959652623020395
https://www.sciencedirect.com/science/article/pii/S0956053X2200040X