Pyrolysis analysis of polyethylene terephthalate: effects of carrier gases (N2, He, and Ar) and zeolite catalyst (A4) on yield

Abstract

AbstractPolyethylene terephthalate, the main material used for beverage bottle packaging, accounts for an average of 7.6% of all plastic waste in Europe. This material is not biodegradable and takes several centuries to decompose. The pyrolysis process in the presence of a catalyst and carrier gases can convert PET waste into solid, liquid, and gaseous materials that can be utilized as fuel. This study evaluated the effects of different carrier gases on the pyrolysis of PET waste in the presence and absence of a zeolite catalyst (A4). The results showed that the catalyst affected the pyrolysis yield; it increased the liquid and gaseous products, as well as the benzoic acid content. However, the effect declined when replacing the carrier gas with a larger molecular weight carrier gas. The alcohol content of the char was larger than that of the wax. The maximum alcohol content was detected under He, implying the direct impact of the carrier on the pyrolysis products. The hydrocarbons identified in the char were affected by changing the carrier gas, and a different distribution of hydrocarbon groups was found by converting the aromatic group into aliphatic compounds. Broadly speaking, in the presence of helium gas and the catalyst, the lowest amount of coke and the lightest compounds were observed. The amount of coke in the presence of nitrogen gas was the same as that of helium gas, but it had heavier compounds. Meanwhile in the presence of argon gas, which has a high molecular mass, more coke and heavier compounds were obtained. © 2022 Society of Chemical Industry (SCI).