Biodiesel Production from Waste Palm Cooking Oil Using Solid Acid Catalyst Derived from Coconut Meal Residue

This study investigates the utilization of coconut meal residue for the preparation of a solid acid catalyst in a one-step simple protocol and its potential use in biodiesel production from waste palm cooking oil in three different reactors. The prepared catalyst was successfully employed for biodiesel production in diverse reaction conditions. The biodiesel yields were 92.7%, 95.5%, and 94.7% in an open reflux reactor, an autoclave reactor, and a microwave-assisted reactor, respectively. The biodiesel yield increases with increasing temperature in an autoclave reactor and with time in all three reactors up to an optimum value. The catalyst can be reused, and biodiesel yields of > 80% were obtained after the fourth run in an open reflux reactor and an autoclave reactor. When considering both the catalytic activity and energy requirement, the autoclave reactor showed better performance. Microwave-assisted biodiesel production is an energy efficient method that shortens the required reaction time compared to conventional heating. However, the stability of the catalyst decreases during recycling in a microwave reactor compared to the other reactors. Fuel properties, such as kinematic viscosity, flash point, pour point, heating value, oxidation stability, and ash contents of the biodiesel satisfied the international standards. Therefore, produced biodiesel can be used. Graphic Abstract