Batch Hydrothermal liquefaction of end-of-life plastic and oil characterization

Benedetta Ciuffi,Edoardo Miliotti,Luca Rosi,Andrea Maria Rizzo,David Chiaramonti,Giulia Lotti,U Desideri,J Yan,L Ferrari

doi:10.1051/e3sconf/202123808004

Benedetta Ciuffi, Edoardo Miliotti + Show 7 more

Open Access

https://doi.org/10.1051/e3sconf/202123808004

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Abstract

Finding a proper way to manage the enormous amount of waste plastic that is globally produced, is one of the main environmental challenges of our times. Among the different types of chemical recycling, Hydrothermal Liquefaction (HTL) appears as a potential method for the treatment of plastic waste mixes, for sustainable production of biocrude or chemicals with high added value. In this work hydrothermal liquefaction reactions were carried out on a polymeric residue, obtained from an industrial plastic waste collection and recycling process. The residue has a heterogeneous composition consisting not only of polymers but also paper and metals. Two batch experiments were performed in a stainless-steel Parr autoclave at 340 °C, investigating a residence times of 5 hours and the use of an alkaline catalyst (NaOH). The oils obtained from the reactions, as well as the aqueous phases, have been analysed by different analytical techniques such as: FT-IR spectroscopy, GC-MS, GC-FID, IC. The operating conditions used in this work, allowed the degradation of cellulose and polymers with reactive sites for hydrolysis such as PET, nylon and PVAc, while polyolefins (PE, PP) were not attacked. The use of a basic catalyst favoured a greater hydrolysis rate.

Highlights

The multifunctionality and the relatively low cost of plastic, make it an omnipresent material in everyday life and its global production is continuously increasing year after year
The operating conditions used in this work, allowed the degradation of cellulose and polymers with reactive sites for hydrolysis such as polyethylene terephthalate (PET), nylon and PVAc, while polyolefins (PE, PP) were not attacked
Packaging by far represents the largest end-use market [2]. Most conventional plastics such as polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC) and polyethylene terephthalate (PET), are non-biodegradable and their increasing accumulation in the environment has been a threat to the planet [3,4,5]

Summary

Introduction

The multifunctionality and the relatively low cost of plastic, make it an omnipresent material in everyday life and its global production is continuously increasing year after year. Among the different types of chemical recycling, Hydrothermal Liquefaction (HTL) appears as a very promising method for the sustainable production of biocrude [8] This technique has high potential as an environmentally friendly green process due to the superior properties as chemical reaction media [9]. Starting from our knowledge in the field of HTL on biomass, in this work we used the hydrothermal liquefaction reaction to study a real processing residue of plastic waste, coming from a recycling plant in northern Italy. This residue has a heterogeneous composition consisting of a large variety of polymers, paper and metals. To the best of the Authors knowledge this is the first study about a real plastic residue containing polyolefins but a mix of different waste polymers, paper and metals

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