From waste tire to high value-added chemicals: an analytical Py-GC/TOF-MS study

A Pyroprobe 5000 pyrolyzer connected to a gas chromatography-time-of-flight mass spectrometry (Py-GC-TOF-MS) was used to analyze the decomposition behavior of waste tire (WT). Effects of several typical parameters such as heating rate, atmosphere, reaction temperature, retention time, and zeolites on molecular composition and relative contents of the liquid products were investigated. Without added zeolite, the pyrolysis products mainly consisted of limonene, 1,4-pentadiene, and monocyclic aromatic hydrocarbons (MAHs) such as benzene, toluene, ethylbenzene, and xylene (BTEX). L-limonene was the dominant fraction (> 85%) of the limonene. Temperature and time presented the most significant effect on the liquid products' molecular composition and relative content, and increasing temperature and time reduced the contents of alkenes and increased the concentration of MAHs. With added zeolite, the molecular composition of the liquid products was greatly affected. All the liquid products produced with zeolite had higher MAHs and lower alkenes compared with those without added zeolite. Among the zeolites tested, Hβ was the most beneficial catalyst to the production of aromatic hydrocarbons as the MAHs reached the highest value of 53.09%. The N, S-compound mainly consisted of benzothiazole and 2-methyl-benzothiazoles-important rubber accelerators. The O, S-compound mainly consisted of sulfones or sulfoxides.