(403a) Hydrothermal Liquefaction of Plastic Waste

The escalating production and disposal of plastic waste pose a significant environmental challenge in recent times. Conventional waste management strategies have often neglected plastic waste's potential as a renewable energy source and petrochemical feedstock. Hydrothermal liquefaction (HTL), a promising technology, has emerged as a sustainable solution to address these challenges. HTL is distinguished by its use of water as a solvent, leveraging environmental and economic benefits in transforming waste feedstock into an oil product (HTL oil), that is similar to the compositional characteristics of crude petroleum. The aim of the present study is the application of HTL for converting polyethylene (PE) waste into HTL oil, thereby presenting a novel approach to managing plastic waste.

Polyethylene (PE) was chosen because it is one of the most common consumer plastics and forms a major fraction of municipal plastic waste. In the present topic, polyethylene pellets were utilized as a feedstock in HTL processes to produce oil products, investigating the impact of various operating conditions on oil yield. Plastic waste is often contaminated, these impurities can be inherent in the form of additives used to render different physical characteristics to the consumer product. The presence of such additives/impurities can compromise the recycling efforts. To combat the issue, experimental runs were also carried out with samples of PE mixed with a known impurity, and the impact of such impurities was then monitored on oil yield (and composition) to determine the best HTL protocol.

Our findings reveal that HTL oil with a composition and purity suitable for use in fluidized catalytic crackers can be produced, effectively reducing the net demand for crude oil in refineries. This study underscores the potential of HTL in transforming plastic waste into valuable HTL oil, contributing to a circular economy, and offering a sustainable alternative to conventional waste management and energy production methods.