Abstract

To understand the influence of support materials on the reactivity of catalysts, four nickel- based catalysts supported on different materials (ZrO2, TiO2, Nb2O5, and Al2O3) were developed and investigated in the carbon nanotubes production from catalytic pyrolysis of polyethylene using two-stage fixed bed reactor. The results showed that the Ni/Al2O3 catalyst generated the highest carbon material yield of 36.5 wt%, while the order of carbon material yield was Ni/Al2O3 > Ni/TiO2 > Ni/ZrO2 > Ni/Nb2O5. To explore the correlation between catalysts properties and carbon products, the essential structural characteristics of fresh catalyst and reacted catalyst were analyzed by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (TEM), temperature program oxidation (TPO), nitrogen adsorption measurements and Raman spectroscopy. The Ni/Al2O3 catalyst with the highest surface area, abundant pore structure, and moderate metal-support interaction promoted the decomposition of pyrolysis volatiles to produce carbon nanomaterials, which were consist of carbon nanotubes (CNTs). CNTs are the main component of carbon materials produced, accounting for a relatively high proportion. In comparison, the large metal active particles and weak metal-support interaction of Ni/TiO2 catalyst had a negative impact on the formation of CNTs, generating many fishbone like carbon nanofibers (CNFs). Moreover, the poor pore structure and larger metal active particles for Ni/ZrO2 and Ni/Nb2O5 catalyst led to a low carbon deposition yield and poor quality of CNTs. The results provide valuable data and theoretical support for the research on the preparation of valuable carbon nanotubes from waste plastics.

Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call