Petrochemical feedstock by thermal cracking of plastic waste

Abstract The thermal cracking is one of the possible ways to obtain petrochemical feedstock from polymer wastes. The properties of the cracking products depend mainly on the type of the raw material. In this study the degradation of different mixtures of polymer wastes (polypropylene and polystyrene) were investigated in a horizontal tube reactor. Temperature of 510–520 °C and residence time of 15–30 min were used. The effects of the concentration of polystyrene on the yields and structure of products were also studied. Moreover, the interaction between the polymers during the pyrolysis was investigated. The products of the thermal cracking were analyzed by gas-chromatography, infrared spectroscopy and different standardized and non-standardized methods. It was found, that the concentration of polystyrene significantly affected both the quantity and quality of degradation products. It was also observed that the presence of the polystyrene in the raw material increased the reaction rate coefficient, and enhanced the degradation rate of polypropylene. By higher concentration of polystyrene in raw materials, the yield of light products considerably increased, furthermore, in the naphtha-like fraction the concentration of aromatics also increased. The characteristics of the products were changed with the polystyrene content in the raw materials. The liquid products had advantageous properties for further utilization as fuel like or petrochemical feedstock applications.

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