Process Solutions for Improving the Stability and Handling Properties of Pyrolysis Oils

Abstract: As governmental regulations and a variety of public and private companies shift toward the realization of a circular economy, chemical recycling technology is seeing increased interest as a key strategy in managing plastic waste. Proof-of-concept and pilot scale chemical recycling have been demonstrated, and numerous plastics-to-feedstocks (PTF) producers and users are beginning to scale up their operations to facilitate the processing of much larger volumes of waste. Polypropylene (PP) and polyethylene (PE) represent the largest volumes of plastic waste, and thus many of the facilities that have been built or are being built are geared toward converting PP and PE into what is known as pyrolysis oil. Pyrolysis oil can then be used as a feedstock for a variety of processes, including as a feed for steam crackers that are used to produce ethylene used in the production of virgin PE resins, thus completing the full lifecycle of polyolefin use, waste, and reuse.

Nalco Water has been and continues to be deeply involved with both producers and users of pyrolysis oils as we work with these customers to understand the challenges presented by these streams and develop potential solutions. Over the course of this work, key areas of concern have been identified, including cold flow handling behavior and stability (particularly with regards to the formation of sediment, gums, and/or films). Treatment with various chemical additives provides customers with options for addressing these challenges and improving the overall properties and performance of the pyrolysis oil stream.

Here we will provide a discussion of broad industry trends around chemical recycling (with particular focus on PE and PP recycling), initial findings around the challenges associated with pyrolysis oils, and chemical treatment options that can be considered and have been demonstrated at lab scale.