Production of valuable chemicals via multiphase catalytic pyrolysis of hazardous waste expanded polystyrene using low cost CaCO3 solid base catalyst

Abstract

In the present research work, multiphase catalytic pyrolysis (in-situ catalytic cracking) of waste expanded polystyrene (WEPS) has been carried out using calcium carbonate (CaCO3) as a solid base catalyst. The multiphase catalytic pyrolysis of WEPS has been conducted at different temperatures ranging from 400oC to 700oC at a heating rate of 15 oC/min and feed to catalyst ratio of 20:1. The thermal pyrolysis of WEPS has produced a maximum liquid yield of 94.37 wt.% at a reaction temperature of 650oC and heating rate of 15 oC/min. Whereas, the maximum liquid yield of 85.99 wt.% is obtained at a reaction temperature of 550oC and heating rate of 15 oC/min for the multiphase catalytic pyrolysis. The GC-FID analysis confirm that the thermal pyrolysis oil is mainly composed of benzene (0.62 wt.%), toluene (10.21 wt.%), ethylbenzene (0.55 wt.%) and styrene (84.74 wt.%). Whereas, the pyrolysis oil obtained from multiphase catalytic pyrolysis using CaCO3 catalyst contains very high styrene content of 93.24 wt.% along with a very low amount of fuel range hydrocarbons benzene (0.25 wt.%), toluene (2.09 wt.%) and ethyl benzene (0.52 wt.%). Thus, the present study clearly indicates that the basic catalyst CaCO3 shows the high selectivity towards the styrene monomer.