Co-pyrolysis of biomass and waste rubber: Characterization of liquid products

In this study, walnut shell as biomass and Ethylene Propylene Diene Monomer (EPDM) rubber, which has no application area other than direct incineration or carbon black production, creates a problem as waste and is difficult to dispose of in industrial zones, were selected as the elastomer waste for the production of pyrolysis liquid product and pyrolysis water fraction by pyrolysis method. Pyrolysis studies were carried out using waste EPDM, walnut shell and their mixtures at different ratios (75 EPDM-25% walnut shell, 50% EPDM-50% walnut shell, 25% EPDM-75% walnut shell) at 500oC temperature, 10oC/min heating rate and under nitrogen atmosphere. Liquid product was obtained with 32.1% and 20.7% yields in the pyrolysis of waste EPDM and walnut shell, respectively. When co-pyrolysis was applied, a positive synergistic effect was observed and 26.1% liquid product yield was reached with the mixture prepared at the ratio of 50% waste EPDM-50% walnut shell. The liquid product was characterized by applying density, viscosity, FT-IR, 1H-NMR, 13C-NMR, and GC-MS methods. It was determined that the waste EPDM liquid product consisted of a mixture of straight-chain alkanes and alkenes, while the walnut shell liquid product contained predominantly phenolic components. It was concluded that to enrich the aliphatic structures of biomass pyrolysis liquid product that contains oxygenated compounds, co-pyrolysis with waste elastomers would be suitable.