Production of carbon nanotubes via catalytic pyrolysis of polyethylene over Ni/ZSM-5 prepared by ethylene glycol assisted impregnation

The design of efficient catalysts is important for the recycling of plastic wastes. In this study, a series of high-dispersion nickel based catalysts were developed by ethylene glycol (EG) assisted impregnation method and applied for the carbon nanotubes (CNTs) production from pyrolytic catalysis of polyethylene. The effect of the addition amount of EG on the catalyst performance was investigated. Results indicated that the catalysts prepared by ethylene glycol assisted impregnation show a good catalytic performance, comparing with conventional impregnation, and the Ni/ZSM-5-EG(3) catalyst displayed a higher yield of carbon deposits (32.37 wt%), including 289 mg/gPE high-value CNTs. To understand the relationship between the catalyst structure and performance, the physicochemical properties of the catalyst were characterized through various technical means. The results indicated that the addition of EG during the catalyst preparation process effectively promoted the dispersion of nickel metal, resulting in formation of smaller NiO particle size. High dispersion and smaller Ni species could enhance the conversion of polyethylene into carbon nanomaterials. This study provides promising directions for the preparation of high-performance catalysts for the preparation of high-value chemicals from plastics waste.