Experimental investigation on liquefaction of plastic waste to oil in supercritical water. (15th April 2019)

• Record Type: Journal Article
• Authors: Bai, Bin; Jin, Hui; Fan, Chao; Cao, Changqing; Wei, Wenwen; Cao, Wen
• Is Part Of: Waste management. Volume 89(2019)
• Page Start: 247
• Page End: 253
• Publication Date: 2019-04-15
• Subjects: Supercritical water -- HIPS plastic -- Liquefaction -- Operating conditions; Hazardous wastes -- Periodicals; Refuse and refuse disposal -- Periodicals; 363.728
• DOI: 10.1016/j.wasman.2019.04.017
• Languages: English
• ISSNs: 0956-053X

Abstract

Highlights: Liquefaction of HIPS plastic was studied in supercritical water. The effects of different operating conditions on liquefaction were investigated. A novel result was that the product of HIPS is ethylbenzene instead of styrene. The CLE in this study increased by 6 times higher than conventional pyrolysis. Abstract: In order to solve the problem of low thermal conductivity and high viscous molten liquid reaction product in the process of plastic liquefaction, the experiments of high impact polystyrene (HIPS) plastic liquefaction were carried out in supercritical water. In this paper, the effects of different operating conditions (temperature, time, feedstock concentration and pressure) on liquid products were studied. It is found that the novel phenomenon that the liquid products of HIPS plastic were mainly toluene and ethylbenzene rather than styrene, which was a product of polystyrene. The experimental results showed that plastic first depolymerized to form styrene and 1, 3-diphenylpropane, which were then converted to toluene and ethylbenzene. The increase in temperature promoted this transformation process and some traces of polycyclic aromatic hydrocarbons also produced. At 490 °C, the maximum carbon liquefaction rate of 77.0 wt% was obtained, which was 6 times higher than the conventional pyrolysis, and the content of toluene and ethylbenzene were 14 wt% and 51.3 wt%, respectively. Increasing the reaction pressure and prolonging the reaction time all promoted the progress of the plastic liquefaction reaction, while increasing the feedstock concentration caused the carbon liquefaction rate to increase first and then slightly decrease.