Multiphase pyrolysis of waste expanded polystyrene and in-situ hydrogenation of pyrolysis oil on silica-alumina supported nickel catalyst for the production of fuel range paraffinic and aromatic hydrocarbons

Abstract

In this work, thermal and catalytic pyrolysis of waste expanded polystyrene (WEPS) have been investigated in a laboratory designed semi-batch reactor in the temperature range of 400-700℃ and heating rate of 15 ℃/min to produce gasoline range lower paraffins and valuable aromatics i.e., benzene, toluene and ethylbenzene (BTE). Three different type of reactor arrangements i.e., liquid phase/A-type, vapour phase/B-type and multiphase/AB-type have been used to conduct the catalytic pyrolysis of WEPS using nickel on silica-alumina catalyst. The thermal pyrolysis of WEPS produced highest liquid yield of 94.37 wt.% at a temperature of 650℃ and heating rate of 15 ℃/min, whereas, liquid phase/A-type, vapour phase/B-type and multiphase/AB-type catalytic pyrolysis produced highest liquid yield of 88.54 wt.%, 83.21 wt.%, and 81.15 wt.%, respectively, at the same heating rate of 15 o C/min and at the temperature of 600℃, 550℃, and 550℃, respectively. The pyrolysis oil obtained from thermal pyrolysis mainly contains styrene monomer of 84.74 wt.% and very less BTE content of 11.38 wt.%. Among, the all types of catalytic pyrolysis, AB-type/multiphase pyrolysis produced pyrolysis oil with highest amount of BTE content of 28.56 wt.%. Furthermore, the pyrolysis oil obtained from A-type, B-type and AB-type catalytic pyrolysis contains low styrene content of 69.94 wt.%, 65.67 wt.% and 55.55 wt.%, respectively, as compared to thermal pyrolysis (84.74 wt.%).