CHEMICAL ENGINEERING TRANSACTIONS VOL. 70, 2018 A publication of The Italian Association of Chemical Engineering Online at www.aidic.it/cet Guest Editors: Timothy G. Walmsley, Petar S. Varbanov, Rongxin Su, Jiří J. Klemeš Copyright © 2018, AIDIC Servizi S.r.l. ISBN 978-88-95608-67-9; ISSN 2283-9216 Effect of Experimental Conditions on Co-Pyrolysis of Pre- Treated Eucalyptus Blended with Plastic Wastes Filomena Pinto*, Filipe Paradela, Florbela Carvalheiro, Luís C. Duarte, Paula Costa, Rui André LNEG, Estrada do Paço do Lumiar, 22, 1649-038 Lisboa, Portugal filomena.pinto@lneg.pt Eucalyptus has been largely used in the pulp and paper industry in Iberian Peninsula, due to its fast growth and high productivity. This eucalyptus utilisation has generated high amounts of wastes, including leaves, branches and stumps. Hence, these wastes were selected for the co-pyrolysis studies to produce liquid fuels or raw materials. As an alternative to the conventional biomass pyrolysis, biomass was pre-treated under mild acidic conditions to obtain valuable sugar-rich stream to be used in fermentation and the solids rich in lignin were mixed with PE (polyethylene) wastes to be used in co-pyrolysis. The pre-treatment process seems to have weakened initial macromolecular structure of eucalyptus wastes and thus might have helped chemical bonds breakdown during co-pyrolysis. The results obtained so far have shown that PE presence seems to have favoured the biomass conversion. The effect of experimental conditions using Response Surface Methodology (RSM) was studied. There was a good agreement between theoretical and experimental data. The highest liquid yield (78 % wt) was obtained at 380 ºC and for the reaction time of 20 min. These conditions led to the lowest gases yield (7 % wt) and also to the lowest solids yield (14 % wt). 1. Introduction Modern societies need to find alternative liquid fuels to fulfil the needs for long distance transportation sector. Pyrolysis has been studied to attain this objective. Pyrolysis technology has been widely applied for converting biomass into liquid biofuels, especially fast and flash pyrolysis and there is huge information available. Bio-oil yields from 60 - 75 % have been reported (Bridgwater, 2012). Liquids produced by biomass pyrolysis have some unfavourable characteristics, namely: high contents of solids, ash, oxygen-containing compounds and water and chemical instability. Thus, they are not suitable to be used as fuel in conventional engines without expensive upgrading processes that use specific catalysts and hydrogen pressure (Bridgwater, 2012). Though the quality of the oil may be improved, the associated costs may make the upgrading processes economically unattractive (Pinto et al., 2016). Thus, an alternative to the conventional biomass pyrolysis was studied. First eucalyptus wastes were pre-treated under mild acidic conditions, which removed the hemicellulose fraction and produced valuable compounds, like oligosaccharides with possible applications in the food and pharma industries and monosaccharides that can be upgraded by fermentation. The solids obtained after this pre-treatment were richer in carbon and lignin and were used in pyrolysis tests. As the hydrothermal pre-treatment weakens biomass initial macromolecular structure, pyrolysis process is expected to be facilitated. Co-pyrolysis of pre-treated eucalyptus solids blended with polyethylene (PE) wastes was studied, with the aim of solving the problems related to the undesirable properties of bio-oils produced from biomass pyrolysis. This may also solve the problems related to the seasonality of some biomass wastes. Plastic waste contains high levels of hydrogen and reduced oxygen as compared to biomass (Xue et al., 2015). Thus, plastics can supply hydrogen to the co-pyrolysis reaction medium and adjust the carbon, hydrogen and oxygen content in the feedstock, improving the quality of the bio-oil produced (Chen et al. 2016). Brebu et al. (2010) also stated that the possible synergistic effects observed during pine pyrolysis with synthetic polymers were due to the fact that polyolefin polymers could supply hydrogen that could promote thermal conversion of the biomass, thereby DOI: 10.3303/CET1870133 Please cite this article as: Pinto F., Paradela F., Carvalheiro F., Duarte L.C., Costa P., Andre R., 2018, Effect of experimental conditions on co- pyrolysis of pre-treated eucalyptus blended with plastic wastes , Chemical Engineering Transactions, 70, 793-798 DOI:10.3303/CET1870133 793