The physicochemical properties of liquid biofuel derived from the pyrolysis of low-quality rubber waste

This research explores the potential of low-quality rubber waste as a feedstock for liquid biofuel production via pyrolysis , achieving a conversion rate of 65–70 %. The study presents a comprehensive analysis of waste rubber pyrolysis oil (WRPO) using FT-IR, 1 H and 13 C NMR , and GC-MS techniques to identify its chemical composition and fuel properties . FT-IR analysis reveals a complex mixture of saturated and unsaturated hydrocarbons , aromatic rings , and oxygenated compounds, while NMR analysis confirms the diverse chemical structure of WRPO. GC-MS identifies key compounds, including d -Limonene, Dimethyl phthalate , Methyl hexadecanoate , and Oleic acid methyl ester , with 18.49 % saturated hydrocarbons and 81.51 % unsaturated hydrocarbons. The TGA results show that WRPO exhibits evaporation and thermal decomposition characteristics similar to B10 diesel , with evaporation beginning below 40 °C and complete decomposition at 300 °C, highlighting its potential as an efficient and environmentally friendly biofuel. Fuel property testing reveals WRPO has a kinematic viscosity of 1.47 cSt, a density of 785 kg/m 3 , and favorable low pour and cloud points (<−5 °C), making it suitable for cold climates. However, WRPO has a lower heating value of 9675 kcal/kg compared to B10 diesel (11083 kcal/kg) and a high acid number of 4.24 mg KOH/g, which may lead to oxidation and corrosion. In conclusion, WRPO shows considerable promise as a biofuel but would benefit from blending with higher-energy fuels, such as B10 diesel, palm oil biodiesel , or waste cooking oil biodiesel , to improve its stability, combustion efficiency , and heating value . This blending strategy enhances WRPO's potential for sustainable biofuel production and engine use.