Thermochemical Recycling of Polystyrene by Pyrolysis: Importance of the Reflux to Maximize the Production of Styrene and BTEX
Nabil Hassibi, Yireth Andrea Vega-Bustos, Mohamed Hechmi Aissaoui, Guillain Mauviel, Valérie Burklé-Vitzthum
Abstract
Chemical recycling of polystyrene (PS) via pyrolysis is of great importance for both environmental and economical purposes. In this work, a specially designed laboratory semibatch glass reactor apparatus equipped with a reflux condenser was developed and investigated for the pyrolysis of PS at 480 °C with nitrogen as the carrier gas and operating at atmospheric pressure with the main goal of improving the recovery of the styrene monomer and benzene, toluene, ethylbenzene, and xylene (BTEX) components. A set of experiments were carried out with and without a reflux condenser. The upper temperature of the reflux condenser was between 200 and 400 °C depending on the amount of heat applied to the reflux condenser wall. A comprehensive gas chromatograph (GC-MS/FID) coupled with a μ-GC-TCD was used to provide an exhaustive characterization of the liquid and gaseous products. The use of reflux influenced the yields of styrene, ethylbenzene, and toluene in the liquid output and the C 1 –C 4 content of the gaseous output. The mass fraction of the styrene monomer related to the analyzed oil from the GC-MS/FID reached a maximum of 81.2 wt % with an optimal reflux temperature of 200 °C, whereas styrene only represented 59.3 wt % when the reflux was not used. The present study illustrates the significant impact of the presence of the reflux on the liquid and gas yields by maximizing the molecules of interest, especially those corresponding to styrene, toluene, and ethylbenzene comparably to usual pyrolysis without reflux.