Upcycling of palm fronds and expanded polystyrene waste for producing liquid fuels with enhanced octane rating

• Pyrolysis oil derived from PF and EPS has the potential to enhance RON of gasoline. • Around 40 % yield of oil phase of light fraction can be recovered from pyrolysis oil. • Oil phase of light fraction derived from PF:EPS of 10:90 contains >95 % of MAH. • Prediction RON based on GC-DHA of the oil phase of the light fraction was 106. • Addition of 5 % of the oil phase to gasoline increased the RON from 90 to 91.5. Expanded polystyrene (EPS) waste from food containers and protective packaging poses a significant threat to the environment. Similarly, palm fronds (PF), which are byproducts of oil palm plantations, are often left to decompose after harvesting. Both EPS and PF serve as potential raw materials for energy production. Co-pyrolysis, a process that utilizes EPS waste and PF together, is a promising method for advancing the circular economy. This research aimed to analyze the composition of the light fraction of pyrolysis oil and to evaluate the effective use of this light fraction to enhance the research octane number (RON) of gasoline. The co-pyrolysis process was conducted using various mass ratios of PF to EPS as 10:90, 82:18, and 90:10 at temperatures of 300, 400, and 500 °C in a bench-scale unit with an 8-liter reactor capacity for feed. Under various temperatures and mass ratios of PF to EPS, the yield of pyrolysis oil ranged from 9.67 to 83.12 wt.%. To separate the light fraction around the gasoline boiling point, the pyrolysis oil was treated with a rotary vacuum evaporator. A higher amount of light fraction was produced from pyrolysis oil with a PF to EPS mass ratio of 10:90. The separated light fraction consisted of two phases: an oil phase and an aqueous phase. The yields of the oil phase were 39.99 %, 45.17 %, and 42.50 % for pyrolysis oil produced at 300, 400, and 500 °C, respectively. The oil phase of the light fraction was analyzed using gas chromatography-detailed hydrocarbon analysis (GC-DHA) to predict its research octane number (RON). The oil phase produced from a PF to EPS mass ratio of 10:90 at 300 °C had a higher RON value of 106. This oil phase contained 98.41 % monoaromatic hydrocarbons, with the main chemical compounds being 44.0 % styrene, 27.9 % ethylbenzene, and 16.6 % α-methylstyrene. Incorporating 5 % by volume of this oil phase into 95 % gasoline increased the RON from 90.0 to 91.5. In line with the principles of a circular economy, the presence of EPS waste and palm fronds—currently underutilized materials—is reduced and repurposed in the energy sector. This is achieved through the co-pyrolysis process, followed by the separation of lighter fractions for liquid fuel application.