(530a) Effect of Acidic Pyrolyzed Hydrochar on Hydrothermal Liquefaction of Waste PVC
AIChE Annual Meeting
Wednesday, November 16, 2022 - 12:30pm to 12:51pm
The United States generates the most waste plastic waste per capita in the world, with the average American generating 130 kg each year (42 million metric tons). Waste Polyvinyl chloride (PVC) is one of the main portions of waste plastic, which is a halogenated plastic listed as number 3 in the recycle class. Halogens possess a significant risk to waste-to-energy as well as any other thermochemical conversion- resulting in landfilling the entire waste PVC. Among other dehalogenation pathways, hydrothermal pathways have been recently proposed. In subcritical conditions, water reacts with PVC and leaches chloride from the solid. Hydrothermal reactions are often catalyzed by acids. In this study, the effect of hydrothermal liquefaction (HTL) of waste PVC is investigated in presence of acidic pyrolyzed hydrochar. Pyrolyzed hydrochar was prepared by acidic hydrotreatment carbonization of pineapple waste and resulting hydrochar was pyrolyzed at 400 °C in the presence of CO2. Pyrolyzed hydrochars are acidic, stable, porous, and containing acidic functional groups. Pyrolyzed hydrochar was co-fed with PVC during HTL to enhance conversion, dehalogenation, and crude quality. HTL experiments were performed using a Hast-C Parr batch reactor at 300-350 °C, 0.25-4 h of reaction times, and 0-20% char to PVC ratio. The results showed that pyrolyzed hydrochars enhance HTL conversion with a maximum value of 24.7 wt% at 5 wt% char content at 350 °C and 0.5 h. Furthermore, crudes included far less chloride and significantly more carbon and hydrogen, resulting in a significantly greater heating value. Finally, the results demonstrated that moderate HTL conditions can efficiently remove chlorine from feedstock and shift it into the aqueous phase, demonstrating the potential of converting PVC to clean solid fuel using HTL.