Speaker
Description
Thermochemical conversion of carbonaceous wastes into valuable carbon nanomaterials via catalytic pyrolysis is one of the promising measures to solve the waste pollution crisis. Additionally, the as-produced carbon nanomaterials of high value may incentivize waste collection and provide economic benefits. In this study, a sustainable one-pot synthesis protocol was developed to produce carbon nanotubes (CNTs) from plastic wastes. Various Ni-based materials integrated with Group 2 alkaline earth metal elements (X) were prepared as catalysts for the process, and the impact of Ni-X interactions on CNTs production was investigated. The results indicated that the carbon yield and morphology of the resultant CNTs were significantly affected by the Ni-X interactions. Specifically, Ni-Ca presented the highest carbon yield (6.4%), whereas Ni-Mg and Ni-Ba exhibited the lowest carbon yield (~3-4%). The NiMo-Mg catalyst generated a high CO2/CH4 environment during pyrolysis, while NiMo-Ba exhibited slower catalytic cracking of polymeric chains from plastic wastes, both of which are unfavorable for CNTs growth. Meanwhile, NiMo-Ca facilitated higher carbon recovery, likely due to its creation of a low CO2/CH4 environment via CO2 methanation. Additionally, Ni-Mg tended to produce distinct and thinner CNTs, while NiMo-Ba yielded carbon flakes with numerous irregular cokes. Further investigation into optimization studies indicated that increasing pyrolysis temperature and duration led to reduced carbon yield. This study also provides valuable insights from the pyrolytic gas formation and carbon nucleation phase to the later CNTs growth phase. Overall, it is expected to improve the understanding of the sustainable synthesis of valuable carbon nanomaterials from carbonaceous waste.
