Influence of Stainless-Steel Catalyst Substrate Type and Pretreatment on Growing Carbon Nanotubes from Waste Postconsumer Plastics

Abstract

This study is concerned with the “up-cycling” postconsumer wastes into the value-added products of multiwall carbon nanotubes (CNTs). It investigated combinations of methods for pretreating different types of stainless-steel catalysts that increase the yield of CNTs form common waste plastics. The polymers were pyrolyzed at 800 °C, in nitrogen, and their gaseous pyrolyzates were passed over fixed catalyst substrates preheated to 800 °C. The substrates consisted of SS-304, SS-316 and SS-316L fine stainless-steel wire-cloths. Therein synthesis of CNTs took place by chemical vapor deposition (CVD). The wire-cloths were used either as-received or chemically etched by acid wash and/or heat-treated in air, nitrogen or helium at 800 °C, and then rapidly air-quenched. Results showed that the catalyst type, composition and pretreatment method, as well as the type of feedstock, are all influential on the yields and physical characteristics of the synthesized CNTs.