Development of Novel Heterogeneous Catalysts from Nigerian Iron Ore and Solid Waste Streams for Biodiesel Production via Transesterification

The development of highly active, stable, and low-cost heterogeneous catalysts from Nigerian waste and mineral resources represents a significant opportunity to improve the economics of biodiesel production while providing sustainable utilisation of domestic natural resources. This study develops and characterises novel heterogeneous solid base catalysts derived from Itakpe iron ore in Kogi State and palm kernel shell ash in Rivers State by calcination, alkali impregnation, and doping with potassium and calcium oxides, and evaluates their activity, selectivity, and stability for the transesterification of Jatropha and castor oils to fatty acid methyl ester biodiesel. Catalyst synthesis routes were systematically varied, and characterised products were evaluated by XRD, BET, TPD-CO2, TEM, FTIR, and Hammett indicator tests to determine surface basicity, pore structure, and active site nature. Transesterification kinetics were investigated in a batch reactor over a temperature range of 50 to 80 degrees Celsius, with catalyst characterisation before and after reaction to identify deactivation mechanisms. An original kinetic model incorporating competitive adsorption of reactants and products on heterogeneous catalyst surface sites was derived from first principles and fitted to experimental data, demonstrating superior predictive capability over Eley-Rideal and Langmuir-Hinshelwood models. The best-performing catalyst achieved fatty acid methyl ester yield of 97.2% after 3 hours at 65 degrees Celsius with 3 wt% catalyst loading and maintained more than 90% activity over 12 reaction cycles. The study presents an original theoretical kinetic framework and a novel catalyst family derived entirely from Nigerian resources for biodiesel production. Keywords: heterogeneous catalyst, biodiesel, transesterification, Nigerian iron ore, reaction kinetics