Synthesis of Sulphonated Carbon- Base Catalyst from Detarium senegalense Shell for Transesterification of Detarium senegalense Seed Oil

Abstract

This study focuses on the synthesis of a sulfonated carbon-based catalyst from Detarium senegalense shells 
for the transesterification of Detarium senegalense seed oil. The catalyst was prepared by carbonizing the 
shells at 700°C for 3 hours, followed by sulfonation with 98% sulphuric acid at 150°C for 3 hours. The 
Box-Behnken Design (BBD) was used to optimize the catalyst synthesis process, yielding optimal 
conditions of a solid-to-acid ratio of 1:15(w/v), a reaction time of 2.502 hours, and a temperature of 
120.523°C. The performance of the catalyst was evaluated in the transesterification of Detarium 
senegalense seed oil. The synthesized sulfonated solid acid catalysts were characterized by acid-base back 
titration for the determination of total acid density, Fourier transform infrared spectroscopy (FT-IR), X-ray 
diffraction (XRD), Scanning electron microscopy (SEM) and X-ray energy dispersion spectroscopy (EDS). 
Oil extraction from the seeds was optimized using BBD, with optimal conditions determined as 5 hours, 
80.001 mL of solvent, and 15g of substrate. The extracted Detarium senegalense seed oil was characterized 
by its acid value (0.57 mg KOH/g), iodine value (70 g/100 g of I₂), FT-IR, and other physical properties, 
including density, specific gravity, and kinematic viscosity. The catalyst achieved a 78% conversion of free 
fatty acids in the transesterification reactions. Kinetic studies revealed an oil extraction rate constant of 0.63 
and an activation energy (Ea) of 235. kJ/mol.