Influence of plastic content on synergistic effect and bio-oil quality from the co-pyrolysis of waste rigid polyurethane foam and sawdust mixture

Current disposal of end-of-life plastics by landfilling or incineration raises serious environmental concerns, simultaneously representing an irretrievable loss of valuable resources. Especially this is evident for materials that have a complex structure, like polyurethane foams. In this work, co-pyrolysis with sawdust was carried out to analyze and evaluate the product quality for further utilization as alternative fuels. The introduction of polyurethane increased the oil yield but in a limited range since no significant difference was observed between the mixture with 25 and 75% of polyurethane content. In addition, the chemical analysis showed that small addition of polyurethane is sufficient to eliminate most of the oxygenated compounds derived from sawdust. Nevertheless, the obtained liquid products are mostly benzenamines that do not meet the criteria for fuel composition. Analysis of the synergistic effect shows that the strongest impact is visible for a small branch of plastic content where liquid yield was promoted at the expense of gas. With a further increment of plastic content, this effect fades away, except for the solid residue where remains constant. Finally, a brief analysis of the gaseous fraction showed that obtained products are preferred in syngas composition, with notable hydrogen yield as the most valuable constituent.