Prospects for the utilization of bio-oil-derived chemicals generated via co-pyrolysis of biomass and polyethylene terephthalate (PET)

Abstract

The global concern about plastic is a matter of great importance. Coprocessing biomass and polyethylene terephthalate (PET) through pyrolysis can represent a strategy to reuse these materials, transforming them into products of industrial interest. Thus, this study aims to understand the influence of the co-pyrolysis of biomass and PET on bio-oil (BO). The PET quantities used were 0 %, 15 %, and 25 % of the eucalyptus biomass dry basis. The co-pyrolysis was performed in a fixed-bed reactor in a low-oxygen atmosphere without gas entry at a final temperature of 450°C and three heating rates (1, 3, and 5°C.min⁻¹). The liquid fraction underwent double distillation, producing purified bio-oil (BOP) with yields of 54 %, 57 %, and 55 %, respectively, influenced solely by the heating rates of 1, 3, and 5°C min⁻¹. After purification, BOP's pH, density, and viscosity were analyzed. The chemical composition of BOP was subject to GC-MS analysis. The addition of PET and the variation in heating rate influenced the composition of the BOP produced. The liquid density decreased as the PET proportion in the biomass increased. The heating rate increase reduced BOP's pH from 2.75 to 2.61. Therefore, lower heating rates and PET proportions tend to increase the viscosity of BOP. Ketones were the most representative organic compounds in all evaluated materials, followed by phenols, furans, and pyrans.