Title:
Can Plastic Waste be Used to Improve Bio-Crude Oil from the Hydrothermal Liquefaction of Technical Lignin?
Author(s):
Marx, S., Venter, R.J., Visser, E., Swanepoel, P.
Document(s):
Paper
Slide presentation
Abstract:
The growing concern over the amount of plastic waste entering the environment without appropriate disposal or recycling motivates to search for new ways in which especially plastics that are difficult to recycle can be re-used. Lignin is a low-value by-product from the pulp and paper industry that produces a low yield of bio-crude oil via hydrothermal liquefaction (HTL) with a high oxygen content of above 35%, making it difficult for further upgrading to transportation fuels or biopolymers. Furthermore, the H/C ratio of lignin-derived bio-crude oil is low and would require an additional hydrogen source during processing to improve its fuel value. The co-HTL of lignin with polystyrene to evaluate the effective of polystyrene to improve the bio-oil yield and quality was investigated in this paper. Poly (methyl methacrylate), generally known as Perspex was co-liquefied with technical sodium lignosulphonate in the presence of calcium oxide as catalyst while polystyrene was co-liquefied in the presence of H-ZSM5 as catalyst. A 20 mass % addition of Perspex to lignin improved the bio-crude oil yield by a factor 8.8 to 3.1 mass %. Co-liquefaction of 50 mass % polystyrene with lignin improved the bio-crude oil yield by a factor of 63 to 22.2 mass %. Co-liquefaction with Perspex did not improve the H/C or O/C ratio, but no acids were detected in the bio-crude oils using gas chromatography coupled to mass spectroscopy (GC-MS) analysis. Furthermore, co-liquefaction with Perspex lowered the number of heavy components (boiling range above 370 °C) in the bio-crude oil from 54 mass % to about 27 mass% while improving the diesel fraction from 42 mass % to 71 mass %. Co-liquefaction with polystyrene reduced the H/C ratio from 1.3 to 0.97 and the O/C ratio from 0.58 to 0.05 while improving the higher heating value (HHV) from 25.7 MJ/kg to 37.2 MJ/kg. However, the fraction of heavy components in the bio-crude oil was only slightly reduced to 50.5 mass % and the diesel fraction only slightly improved to 49.5 mass %. It was concluded from this work that unrecyclable waste plastics could be used to significantly improve the bio-crude oil yield and quality when co-liquefied with technical lignin. This result could have a significant impact in reducing the amount of polystyrene that ends up on landfill sites or in water resources. Re-using waste plastics and low-value lignin to produce high quality bio-crude oil that can be used as polyol for bio-polymer production or hydrotreated to renewable diesel supports not only the circular economy, but also contribute towards the UN Sustainable development coals of climate action and life below water.
Keywords:
lignin, waste, synergy, biocrude, plastic, HTL
Topic:
Biomass Conversion to Intermediate Bioenergy Carriers and Sustainable Biofuels
Subtopic:
Hydrothermal processing
Event:
30th European Biomass Conference and Exhibition
Session:
5DO.3.1
Pages:
862 - 866
ISBN:
978-88-89407-22-6
Paper DOI:
10.5071/30thEUBCE2022-5DO.3.1
Price:
FREE
