Experimental and computational investigations of biodiesel production from castor oil using Li-doped salmon fish bone-supported lanthanum oxide catalyst in a micro-reactor

Ensuring efficient and sustainable biodiesel production is essential for addressing environmental concerns and meeting global energy demands. This study aims to optimize the transesterification of castor oil through the development of a distinctive Li-doped-salmon fish bone (SFB)-supported La2O3 composite catalyst within a micro-reactor setup. The optimal catalyst (3 % Li/SFB-La) was thoroughly evaluated for its physicochemical features employing a range of characterization techniques, including XRD, XPS, BET, FESEM, TEM, TGA/DSC, and FT-IR. According to density functional theory (DFT) calculations, the function of Li dopants, which have a lower electronegativity (0.98) compared to La (1.1), is to enhance the charge transfer capability of La sites, thereby increasing their reactivity with triglycerides. In the interim, we determined the optimized reaction conditions: a 6:1 methanol/oil molar ratio and a 5 wt % catalyst loading at 338 K. Under these parameters, an impressive 99.38 % conversion was achieved within 1.5 h. Furthermore, the 3 % Li/SFB-La composite catalyst exhibited remarkable stability, retaining its high activity throughout 7 cycles without any significant loss of efficacy. Moreover, the transesterification reaction kinetics were thoroughly investigated, revealing a reaction rate constant of 1.17 h−1 and an activation energy of 14.46 kJ/mol.