Identify the impact of pyrolysis temperature on preparation of carbon nanotubes by catalytic reforming polypropylene

Abstract

Catalytic reforming offers a promising method for converting waste plastics into valuable products such as carbon nanotubes (CNTs). The composition of the carbon source plays a crucial role in determining the growth of CNTs because pyrolysis temperature exerts a significant influence on volatilisation. This study investigated the impact of pyrolysis temperature on the formation of CNTs in the presence of an Fe/Al₂O₃ catalyst. A pyrolysis temperature of 500 ℃, generated a liquid product containing a high concentration of long-chain waxy hydrocarbons, while the gaseous products were dominated by C₃H₆ (47 vol%) and C₂H₆ (20 vol%). Increasing the pyrolysis temperature facilitated the formation of CH₄ and aromatic hydrocarbons at the expense of the waxy components. Following catalysis, carbon deposits of > 30 wt% (comprising approximately 80 % CNTs) were obtained at 500 ℃, compared to 20 wt% (with CNTs comprising 60 %) at 900 ℃. In summary, the results suggest that small molecular hydrocarbons, including C₃H₆ and waxy components, promote CNT formation, whereas aromatic hydrocarbons contribute to the formation of amorphous carbon or coke.