Tailored iron-based catalysts for high yield synthesis of carbon nanotubes from plastics

Abstract

Three iron-alumina catalysts were formed using three different precipitation agents being, Urea, Nmethylurea, and N,N’-Dimethylurea which were prepared using a hydrothermal and calcination process. The purpose of this study was to find an optimal catalyst to produce high yields of carbon nanotubes (CNTs) using low-density polyethylene (LDPE) as a feedstock in a two-stage pyrolysisCCVD process. The urea-based catalyst produced the highest yield of CNT per gram of catalyst and subsequent optimisations were made to the process using the same catalyst. The optimum catalytic temperature to grow the CNTs using these catalysts was determined to be 800°C, with lower temperatures producing lower yields of CNTs. In addition, it was found that a higher LDPE-to-Catalyst ratio led to a lower CNT-to-LDPE ratio, indicating that the carbon conversion rate was lower, decreasing the efficiency of the process which in turn adversely affects both the cost of the LDPE feedstock and catalyst if the process is to be upscaled for commercialisation in the future.