Optimisation of the reaction conditions for biodiesel from Parkia biglobosa oil via transesterification with heterogeneous clay base catalyst

Abstract

Transesterification reaction of Parkia biglobosa oil (0.61% w/w free fatty acid and 191.65 (mgKOH/g) saponification value) with methanol to biodiesel using heterogeneous bi-functional Clay-Na₂CO₃ catalyst was carried out. The bi-functional heterogeneous clay base catalyst was prepared using incipient impregnation method. Following grinding and sieving, the raw clay mineral was soaked in 9 ml Na₂CO₃ overnight. It was subsequently dried at 120 °C for 12 h and finally calcined at 450 °C for 4 h. The properties of the prepared catalyst was then studied using FTIR, SEM, UV Spectrum, EDS and XRD. The optimum conditions for the transesterification reaction include 12:1 molar ratio of methanol to oil, 2 wt% concentrations of catalyst, reaction temperature of 60 °C and 1.5 h of reaction. The maximum yield obtained under conditions was 94.7%. With the exception of the oxidative stability wahich was higher than the recommended standard by American and European Union, all the other properties of the biodiesel were within the limits of American Standard (ASTM D6751), European Standard (EN 14,241) and Ghana Standard Authority. The catalyst could be cheap with superior activity for which reason it could be a potential candidate for producing biodiesel from new non-edible Parkia biglobosa oil. The application of the biodiesel produced from Parkia biglobosa will help improve the lubrication properties of diesel fuel blend which will subsequently help reduce engine wear in diesel engines since biodiesel is a good lubricant.