Thermal behavior, kinetics and gas evolution characteristics for the co-pyrolysis of real-world plastic and tyre wastes

Abstract

Investigations into the co-pyrolysis of four kinds of real-world plastics (high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), and polystyrene (PS)) and tyre were carried out in a TG-FTIR instrument. The thermal decomposition behavior, conversion kinetics and gas releasing properties during co-pyrolysis process were investigated. It was found that co-pyrolysis of plastics and tyre delayed the pyrolysis process with a wider decomposition temperature range, when compared with the pyrolysis of individual plastic. The kinetic analysis results indicated that the co-pyrolysis process could be divided into three stages by a single first-order reaction model with the activation energies of 65–87, 34–92, and 138–208 kJ/mol, respectively. A positive synergistic interaction was found between PS and tyre, while the co-pyrolysis of PP/HDPE/LDPE and tyre was negatively influenced. During co-pyrolysis of tyre with four kinds of plastics, CH4 was the majority product for HDPE, LDPE and PP, whereas for PS, the aromatics and C–H containing compounds were the main products. The results regarding co-pyrolysis of plastics and tyres provide an insight into an environmentally friendly recycling technology for polymeric wastes.