Title : Natural zeolite catalysed extraction of liquid fuel from pure and mixed waste plastics using pyrolysis technique
Abstract:
This paper presents a study on the extraction of liquid oil from waste Polyethylene Terephthalate (PET) and High-Density Polyethylene (HDPE) plastics, both individually and in mixtures, using a catalyzed pyrolysis process. The natural zeolite (NZ) samples have been characterized by X-ray diffraction (XRD), and scanning electron microscopy (SEM). The aim of this study was to analyze the characteristics and performance of the process, effect of blending waste plastic oil with diesel (B0, B20, B30 and B50) on fuel properties, and engine emissions characteristics and determine the maximum liquid oil yield by varying parameters, such as catalyst presence, temperature, residence time, feed consumption, and plastic waste ratio. The results showed that the addition of a natural zeolite catalyst increased the liquid oil yield during pyrolysis. The conversion efficiency of pure PET increased from 38.1% to 43.5% by weight, whereas that of pure HDPE increased from 72.8% to 84.6% when the catalyst concentration was 10% and residence time was 45 min. When considering a 1:4 ratio of HDPE to PET, the liquid conversion efficiency was 65.3% by weight, but it increased to 78.4% when the ratio was reversed to 4:1, with an optimal temperature of 425 °C and catalyst concentration of 10%. The study also evaluated engine performance using different fuels derived from PET, HDPE, mixed waste plastic, and diesel and emissions such as CO, CO2, HC and NOx are also evaluate. In case of emission, the waste plastic blend improves NOx emission (except B50), carbon dioxide, and unburned hydrocarbons by 2.8% (B20 at 3600 rpm), 9.8% (B50 at 1300 rpm), and 18.7% (B300 at 1000 rpm) respectively but the emissions of CO are slightly higher at low speeds and almost close to each other at higher engine speeds. The results indicated that PET fuel exhibited the highest average brake torque and power output compared to the other fuels. The specific fuel consumption decreased with increasing engine speed for all fuels. These findings demonstrate the potential of catalytic pyrolysis as an effective method for extracting diesel-like fuel from waste plastics, thereby addressing both the environmental issues associated with plastic waste and the growing demand for petroleum-based fuels.
