Insight into long-chain aliphatic hydrocarbons (C≥7) preparation from co-pyrolysis of reed stems and polypropylene wastes

This study investigated the thermal decomposition characteristics and long-chain aliphatic hydrocarbons (C ≥ 7) (LCAH) preparation during catalytic co-pyrolysis of reed stems (RS) and polypropylene (PP) wastes. A TG-FTIR system and a Py-GC/MS system were employed to elucidate the characteristics of LCAH generation. Both the shift of the DTG peak from 483 to 468 °C and the reduction in activated energy ( E a ) confirm that the co-pyrolysis technique exerted a positive effect on the decomposition of RS and PP. A higher heating rate enhanced this positive synergy. Semiquantitative analysis of FTIR absorption peaks at ∼2960 and ∼721 cm −1 , combined with GC/MS compositional distributions, demonstrate that the co-pyrolysis of RS and PP exhibited a synergistic effect on the LCAH generation. A reforming effect was observed between RS-derived bio-oils and PP-derived bio-oils, resulting in the production of LCAH molecules with an expanded carbon number distribution. Three possible routes were proposed to clarify the LCAH generation during co-pyrolysis of RS and PP. Temperatures of 600 to 650 °C and prolonged secondary reaction time were favorable for improving the yield of LCAH. In the presence of Ni-SiO 2 /ZrO 2 catalyst, the relative content of LCAH in the bio-oils reached 62.70 area%, and the catalyst maintained excellent performance in consecutive 5 runs.