Transesterification of used vegetable oil using BaAl2O4 spinel as heterogeneous base catalyst

Abstract

Present study aim to synthesize biodiesel using a heterogeneous base catalyst, barium aluminate (BaAl2O4) and used vegetable oil (UVO) feedstock via transesterification reaction. The catalyst was synthesized using co-precipitation route and characterized using techniques TG-DT analysis, XRD, FTIR, HRSEM-EDX, textural properties, and basicity. The best experimental condition of transesterification reaction was found at methanol to oil molar ratio 21:1, catalyst dose 4 wt%, reaction temperature of 65 ± 0.5 °C for 150 min of reaction duration and 600 rpm stirring rate which resulted in 93.28% conversion of methyl ester. Five cycle reusability of the synthesized catalyst after high-temperature regeneration was also investigated at optimized reaction conditions. Moreover, kinetics and thermodynamic studies of biodiesel synthesis reaction were also studied and Ea = 61.48 kJ/mol, A = 5.95 × 107 min−1, ΔH = 55.873 kJ mol−1, ΔS = -0.136 kJ mol−1 K−1, and ΔG (at 338 K) = 101.847 kJ mol−1 were obtained respectively. The important fuel properties such as acid value, density, kinematic viscosity (40 °C) calorific value, flash point, fire point, cloud point, pour point, and cetane number of synthesized biodiesel were analyzed and found satisfactory with ASTM D 6751 specifications. In addition, the green chemistry matrix E-factor and PMI values were also formulated.