Laboratory-scale plastic upcycling and green growth: Evaluating the upcycling of plastic waste into carbon nanotubes from economic and environmental aspects

Abstract

It is known that gas generated through plastic pyrolysis is abundant in hydrocarbons and can serve as a raw material for carbon nanotubes (CNTs). However, there has been no research evaluating both the economic and environmental feasibility of an upcycling process using pyrolysis gas to produce CNTs. A comparative evaluation was conducted between the upcycling process and the conventional process using methane as a carbon source, and each process was performed at laboratory scale. We report that the cost of the upcycling process (2,999 $ kg- 1) is comparable to that of the conventional process (2,930 $ kg- 1), and that this slight cost disadvantage can be mitigated by reducing the Ar flow rate by 20%. Upcycling process involving pyrolysis has a greater impact on climate change than conventional process. However, this disadvantage can be significantly mitigated up to 19.38 kgCO2eq by substituting the power generation method with renewable energy source. Enhancing the prerequisites and technological maturity of upcycling processes can contribute to the expansion of the pyrolysis industry and the realization of a circular economy, thereby promoting green growth.