Feasibilities of producing high-value carbon nanotubes from waste plastics by spray pyrolysis

Producing carbon nanotubes (CNTs) from waste plastics could enhance the economic feasibility of the waste management process. Spray pyrolysis is a practical and promising method in this research area. However, the synthesis of CNTs by a spray pyrolysis method is highly reliant on a variety of parameters. Therefore, parameters, including the amount of waste plastics (polypropylene), the catalyst feeding rate and the concentration of the catalyst, and the reaction temperature, were investigated in this work. Results indicate that the reaction factors can influence the carbon deposition and carbon nanotubes yield (CNTs yield). The formed catalyst size played a significant role in the synthesis process. The carbon deposition and CNTs yield reached the top at 21.11 mg g⁻¹_plastic and 11.60 mg g⁻¹_plastic, respectively, when the PP amount is 2.0 g, the feeding rate of catalyst is 9.0 mL h⁻¹, the concentration of catalyst is 0.2 mol L⁻¹, and the reaction temperature is 800 °C in this work.