Research progress in the growth mechanism of carbon nanotubes prepared by catalytic pyrolysis of waste plastics

Catalytic pyrolysis technology can convert waste plastics into high-quality carbon nanotubes (CNTs), achieving the recycling and high-value utilization of waste plastics. However, the process of plastic catalytic pyrolysis is complex, with numerous influencing factors, and the growth mechanism of carbon nanotubes is unclear. Therefore, this article elaborates on the influence of plastic structure and pyrolysis process on the growth process and structural characteristics of carbon nanotubes from the perspectives of plastic type, temperature, catalyst, etc., and analyzes the nucleation and growth mechanism of carbon nanotubes. It is found that the type and temperature of volatile matter will affect the structure of CNTs, while the performance of the catalyst will affect the diameter and growth mode of carbon nanotubes. The force between the catalyst and CNTs depends on the type of catalyst, and the carbon diffusion intensity at the boundary of CNTs is influenced by reaction conditions, catalyst and carbon source types. The relative size between the two determines the specific process of CNTs nucleation and growth.This review provides theoretical reference for the understanding of the process of preparing carbon nanotubes from waste plastic pyrolysis and the development of waste plastic resource utilization technologies.