Catalytic Cracking of High Density Polyethylene Pyrolysis Vapor over Zeolite ZSM-5 towards Production of Diesel

Abstract

The upsurge in the amount of plastic pollution has drawn the attention of various researchers in finding the best solution for plastic waste treatment. Pyrolysis of high density polyethylene using ZSM-5 catalyst has been investigated using two-staged reactors consisting of a pyrolysis reactor and a catalytic fixed bed reactor. The effect of the heating rate (2 °C/min, 6 °C/min, 10 °C/min, 14 °C/min, 18 °C/min) of the pyrolysis reactor and reaction time (75 min, 90 min, 105 min) were studied on the yield of products and the quality of pyrolytic oil products. The quality of pyrolytic oil produced was evaluated based on the gross calorific values (GCV) and the paraffin, olefin, naphthenic and aromatic (PONA) compounds distribution, which were used to compare with conventional fuel. The highest yield of oil product was obtained at a reaction time of 75 minutes, where it was 61.05 wt.%, with solid product yield of 0.41wt.% and gas product yield of 38.54wt.%, at a heating rate of 2°C/min. The GCV of oil products were within the range of that of conventional diesel (44 – 45 MJ/kg). The pyrolytic oil products contained mainly C₁₀ to C₂₄ hydrocarbon compounds, which were diesel range hydrocarbon. In terms of the PONA distribution, the composition of paraffin was larger for most of the products, while the composition of naphthenes and aromatic were relatively small with respect to the range for conventional diesel.