Biodiesel Production From Waste Palm Oil Using Palm Empty Fruit Bunch-Derived Novel Carbon Acid Catalyst

Production of biodiesel from waste palm oil (WPO) can provide alternative energy and at the same time reduce the problems created by disposal of WPO. In this study, a novel, inexpensive, and environmental benign carbon acid catalyst is prepared by direct in situ concentrated H₂SO₄ impregnation of palm empty fruit bunch (PEFB) powder and employed for biodiesel production using WPO. The structure and the physiochemical properties of the prepared catalyst (PEFB-DS-SO₃H) are analyzed by acid-base back titration data, energy dispersive X-ray spectroscopy (scanning electron microscopy (SEM)-EDS), SEM, Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and using N₂ adsorption and desorption isotherm data. It is observed that the catalyst has a unique amorphous structure with total acid density of 5.40 mmolg⁻¹, surface area of 5.5 m²g⁻¹, and 0.31 cm³g⁻¹ pore volume. In addition, FT-IR, XPS, and EDS results confirm a successful sulfonation during the catalyst preparation. It is found that fatty acid methyl ester (FAME) yield increases with increasing methanol:oil (molar ratio) and reaction time up to an optimum value. The highest biodiesel yield of 91% is reported under reaction conditions of 5 wt % catalyst, 14:1 methanol: oil (molar ratio), at 65–70 °C after 14 h in an open reflux system. Results show that the catalyst can be reused for four consecutive cycles without significant loss of catalytic activity. Fuel properties of the produced biodiesel are compatible with the international fuel standards for biodiesel.