Catalytic co-pyrolysis of poplar tree and polystyrene with HZSM-5 and Fe/HZSM-5 for production of light aromatic hydrocarbons

The catalytic co-pyrolysis of biomass and plastic waste is a highly effective approach for the production of light aromatic hydrocarbons. In this study, catalytic co-pyrolysis experiments were conducted on poplar tree (PT) and polystyrene (PS) using pyrolyzer coupled with gas chromatography/mass spectrometry (Py-GC/MS). The experiments were carried out at a temperature of 550 °C and a mixing ratio of 1:1. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) techniques were employed for the characterization of HZSM-5 and Fe/HZSM-5 catalysts. The findings indicated that the metallic Fe in the HZSM-5 catalyst led to an enhanced production of monocyclic aromatic hydrocarbons (MAH) during the catalytic co-pyrolysis of PT and PS. The proportion of MAH in the products obtained from HZSM-5 and Fe/HZSM-5 catalyst was determined to be 85.84% and 90.87%, respectively. In the catalytic co-pyrolysis of biomass and plastic waste, several crucial reactions took place, including deoxidation, olefins aromatization, and Diels-Alder reaction between furans and olefins. In the presence of Fe metal, the HZSM-5 catalyst exhibited enhanced selectivity towards valuable MAH while effectively suppressing the formation of polycyclic aromatic hydrocarbons, resulting in an increase in MAH production to 90.87%.