Thermochemical Valorization of Urban Waste: Study on the Co-Pyrolysis of Tree Pruning Residues with PET.
energy transition; waste; tree pruning; polyethylene terephthalate (PET); co-pyrolysis
The rapid increase in global energy demand, driven by population growth, highlights the urgent need for alternative and sustainable sources. Biofuels, produced from renewable biomass, emerge as a viable alternative to fossil fuels, particularly lignocellulosic waste, due to their abundance and low cost. However, bio-oil obtained through pyrolysis presents physicochemical limitations that hinder its direct use. Co-pyrolysis with polymeric waste, such as polyethylene terephthalate (PET), stands out as a promising strategy to improve bio-oil quality, fostering synergistic reactions that favor deoxygenation and enhance product stability. This study evaluated the energy potential of urban waste, such as tree pruning residues, in blends with PET, noting that the addition of the polymer reduced the apparent activation energy and improved thermal stability, with particular emphasis on the 50% PET–tree pruning mixture. The reaction was found to be endothermic, irreversible, and non-spontaneous, and the thermodynamic study indicated a lower enthalpy change compared to pure biomass. The presence of PET led to the cracking of carbon chains in the bio-oil and a significant increase in the porosity of the biochar, thus positioning co-pyrolysis of tree pruning residues with PET as a promising approach for obtaining higher value-added products.