Fatty acid methyl esters production via transesterification of triglycerides from non-edible oil using newly synthesized heterogeneous CoO/Nd2O3 nanocomposite

Abstract

Nowadays energy crisis is a big challenge due to fast depletion, increased consumption and swift increase in human population. Moreover, hydrocarbon-based fuels are responsible of increasing environmental pollution. Biofuel particularly biodiesel has got attention as alternative and clean fuel. Raw source of biodiesel and catalyst designing are important deciding factor for commercialization. In the present study, cobalt oxide/neodymium oxide (CoO/Nd₂O₃) nanocomoposite was synthesized by using the controlled hydrothermal approach followed by calcination. Analytical techniques, such as FTIR, XRD, SEM, and EDX, were utilized to investigate the functional, structural, morphological properties and elemental features of the produced nanocomposite, respectively. The peaks appeared at 661.94, 630.39, and 420.06 cm⁻¹ represent the Co–O, Nd–O and Nd–OH, respectively. The presence of diffraction peaks of both CoO and Nd₂O₃ in XRD pattern represent the formation of nanocomposite. Irregular or rod-like morphology was observed in SEM images. As an energy crop and non-edible nature, Pongamia pinnata’s oil was used for production of FAMEs (fatty acids methyl esters) commonly known as biodiesel. The CoO/Nd₂O₃ nanocomposite was used as a heterogeneous catalyst in transesterification reaction to produce FAMEs. The spectroscopic analysis such as FTIR and NMR (¹H and ¹³C) were used to comprehensively characterize the biodiesel. The emergence of new peak at 1190 cm⁻¹ indicated methoxy methyl (–OCH₃) group representing the formation of FAMEs. Proton nuclear magnetic resonance (¹H-NMR) spectrum shows that 91% of the triglycerides were converted to their FAMEs. The biodiesel composition was identified by GC–MS analysis in which nine different types of FAMEs (saturated such as methyl esters of palmitic, arachidic, behenic and lignoceric acids and unsaturated such as methyl esters of palmitoleic, linoleic, gondoic, erucic, nervonic acid) were found. The highest biodiesel production yield was obtained at optimized oil-methanol molar ratio of 1:18, and catalyst concentration of 1.5 wt%. The physical fuel parameters such as acid number, kinematic viscosity and density were determined as 0.28 mg of KOH/g, 6.98 cSt and 0.85 g/cm³, respectively, which fall within ASTM limits.