Effect of Pyrolysis Temperature Variation on Gasoline Selectivity from Polypropylene Plastic Waste

The objective of this research is to investigate the effect of pyrolysis temperature variation on the selectivity of gasoline fraction from polypropylene (PP) plastic waste. The pyrolysis process was conducted using a semi-batch stainless steel reactor at three different temperatures: 350, 400, and 450°C, each with a constant residence time of 60 min. The liquid products were condensed and analyzed using Fourier transform infrared spectroscopy (FTIR) and gas chromatography–mass spectrometry (GC-MS). Results show that the highest oil yield was obtained at 400°C (85.72 wt %), while 350 and 450°C produced 48.67 and 75.92 wt %, respectively. FTIR analysis revealed the presence of hydrocarbon functional groups including alkanes and alkenes. GC-MS results indicate that 400°C yielded the highest concentration of C9–C11 hydrocarbons, with C9 being the most abundant at 36%, followed by C10 (15%) and C11 (12%). This range corresponds to the gasoline fraction (C5–C12), which peaked at 60.72 wt % at 400°C. Therefore, 400°C is identified as the optimal temperature for maximizing both oil yield and gasoline selectivity in PP pyrolysis.