A review on the synthesis of carbon nanotubes from plastic waste: Influence of manganese as a catalytic promoter

Converting plastic waste into valuable carbon nanotubes (CNTs) presents a transformative solution to the global plastic pollution crisis while significantly reducing plastic waste. This review emphasizes how the different types of plastics used for transforming plastic waste into CNTs can influence the quality and yield of CNT production. It is identified that polyethylene (PE) and polypropylene (PP) serve as optimal feedstocks owing to their higher purities compared to other plastic types, resulting in cleaner CNT synthesis. Additionally, catalysts play a crucial role, with the one-step impregnation method using (Mn+Fe)/MgO demonstrating a superior performance compared to other methods due to an enhanced carbon solubility in α-(Fe_1­xMn_x)₂O₃. Furthermore, manganese functions as an efficient promoter, ultimately improving the CNT yield and selectivity. Overall, it is noted that advancements in sustainable techniques for converting plastic waste into high-value material can have a crucial impact on future innovations in the field. This review not only explores the conversion of plastic waste into CNTs, but it also emphasizes the role of manganese in catalyst enhancement, aiming to produce high-quality CNTs for further research.