Thermo-catalytic pyrolysis of polystyrene in the presence of zinc bulk catalysts

• Zn bulk catalysts (Zn, ZnO and ZnCl2) were used for the degradation of WEPS.
• The Zn bulk catalysts were reported with good catalytic performance.
• The catalysts, increased the selectivity of useful hydrocarbons.
• Zn was found as the best catalyst for EPSW pyrolysis amongst the zinc bulk catalysts.
• The liquid products obtained were separated and characterized.

Zinc bulk catalysts (Zn, ZnO and ZnCl2) were used for the thermo-catalytic pyrolysis of EPSW and were found with high activity and selectivity of products. Thermo-catalytic pyrolysis was carried out using an efficient Pyrex batch reactor. Zn metal catalyst was found as the best catalyst amongst the zinc bulk catalysts for the cost effective pyrolysis of EPSW (expanded polystyrene waste). The yield of liquid products at 450 °C, 120 min heating time and 1:0.2 feed to catalyst ratio was 96.73 ± 0.12 wt.% with 2.47 wt.% toluene, 1.16 wt.% ethylbenzene, 47.96 wt.% styrene monomer and 1.90 wt.% α-methylstyrene. The components of liquid products were separated by fractional distillation and found with further thermal pyrolysis in addition to cyclization and recombination reactions. During the fractional distillation, much product variations were observed. High molecular weight aromatic hydrocarbons decreased with the associated increase of low molecular weight aromatic hydrocarbons, particularly toluene and ethylbenzene.