Published December 2023
The production of base chemicals (C2-C4 olefins and benzene, toluene, xylene [BTX] aromatics) from plastics pyrolysis oil (PPO) is considered to be a viable means to significantly reduce ever-growing global waste plastic and the dependence on greenhouse gas-producing fossil fuels for the production of virgin plastics. Technological innovation is enabling waste plastics to be diverted from landfills and to be converted into useful fuels and chemical feedstocks. A plastic pyrolysis facility receives preprocessed plastic feedstock that has been shredded, dried and cleared of most of the non-plastic contamination. The pyrolysis facility heats this preprocessed feedstock, in the absence of oxygen, until the polymer molecules melt and thermally crack to smaller molecules. The condensable gases are then recovered as pyrolysis oil. This raw pyrolysis oil can subsequently be refined into feedstocks for steam crackers and/or petroleum refineries to make new chemicals, plastics and fuels.
This Process Economics Program (PEP) report looks at how organizations around the world are developing and starting to put to commercial use technologies for upgrading raw PPOs and subsequently processing this PPO in steam crackers and refinery petroleum conversion units for producing base chemicals and fuels. Previously published PEP reports on chemical recycling have covered the production of raw PPOs from various types of waste plastics.
Chapter 1 introduces the report layout while Chapter 2 summarizes the contents of the report and highlights key findings. Chapter 3 gives the current industry status with respect to global and regional thermoplastics consumption, waste generation and recycling levels. Also, PEP’s past coverage of plastics recycling is summarized. Recent announcements on plastics pyrolysis technology development and projects, that are under construction or are in planning, are discussed. The current and future global pyrolysis planned capacities are mentioned. Recent regulatory developments impacting the industry are briefly discussed. Chapter 4 provides a technical overview of thermal degradation of various types of plastics used to make raw pyrolysis oils. A detailed discussion on characterization of PPOs with respect to paraffins, iso-paraffins, olefins, naphthenes and aromatics (PIONA) composition, heteroatom and metal impurities and impact of these on further processing of the raw pyrolysis oil in steam crackers and refinery units is given. Pyrolysis oil purification/upgradation technologies that are in advanced stages and are most likely to be commercially used are reviewed. Pyrolysis oil specifications required for PPO feed to steam crackers and refinery units are provided.
Chapter 5 gives a full PEP evaluation of raw PPO upgradation via two-stage hydrotreatment for diolefin/mono-olefin saturation and impurity reduction to levels acceptable for feed to naphtha steam crackers. The evaluation is done for a 40,000 metric tons per year (t/y) of feed pyrolysis oil capacity unit and includes basis of design, detailed process description, a HYSYS simulation-based heat and material balance table, sized equipment list, inside battery limits (ISBL), outside battery limits (OSBL) and total fixed capital (TFC) cost estimates, and the production cost evaluation for hydrotreated PPO. We consider a generic pyrolysis oil hydrotreating technology based on the patent literature and publications published by various technology developers.
Chapters 6 and 7 review the patent literature and publications for using PPO as steam cracker and refinery feed, respectively. We present published yield data and impact of using PPO feed for naphtha steam crackers and several refinery units. We list commercial references with planned use of PPO in such facilities. PEP production economics evaluation of the impact of feeding 5%-10% PPO in a naphtha steam cracker, delayed coker and fluid catalytic cracker (FCC) units are presented.