Waste Polyolefins to Liquid Fuels via Pyrolysis: Review of Commercial State-of-the-Art and Recent Laboratory Research

With generation of waste plastics increasing, current EU legislation dictates high recovery rates and policy favours waste management technology choices that occupy a high position on the waste management hierarchy. Pyrolysis is a thermochemical conversion technology that can be considered a ‘feedstock recycling’ process and may play an increasing role in integrated waste management systems of the future. The objective of this article is to present a review of current state-of-the-art commercial pyrolysis processes for the production of liquid transport fuels from waste polyolefins (polyethylenes and polypropylenes). Current plastic waste generation and management practices are briefly summarised. Waste management infrastructure in Europe is reliant on landfill, incineration and mechanical recycling, while feedstock recycling plays an insignificant role. Plastic-to-liquid platforms including delocalised pyrolysis followed by centralised upgrading, stand alone facilities, and integrated waste management infrastructure concepts are briefly discussed. Commercial operations and their process configurations are compared. Reactor technology for cracking of plastic waste is presented. Important issues like fuel quality and contamination are also discussed. Fuel finishing operations and fuel additives required to achieve an engine ready fuel are described in the final section. Recently published laboratory research in thermal and catalytic pyrolysis and integrated and co-processing studies are also summarised in this review.