Esterification of free fatty acids ( C8 – C16 ) from coconut oil for bio‐jet fuel precursor production using 12‐tungstophosphoric acid supported on niobium pentoxide

Abstract The growing demand for sustainable aviation fuels has driven the exploration of renewable alternatives to reduce dependence on fossil sources and mitigate environmental impacts. This study investigates the hydroesterification of vacuum‐distilled fatty acid fractions (150–190 and 195–220 °C at 0.1 bar) from coconut oil using 12‐tungstophosphoric acid supported on niobium pentoxide (TPA/Nb 2 O 5 ) as a heterogeneous catalyst. Catalyst characterization via X‐ray diffraction and N 2 physisorption revealed a transition to a hexagonal crystalline phase after calcination at 550 °C, with reduced Brunauer–Emmett–Teller surface area owing to structural reorganization at lower temperatures. Temperature‐programmed desorption of ammonia analysis confirmed predominant strong acid sites associated with Keggin ions, independent of calcination temperature. Catalytic performance was assessed by varying parameters such as catalyst loading, temperature, reaction time, and ethanol‐to‐fatty acid molar ratio in the ethyl esterification of distilled fatty acids and lauric acid (C12) as a model compound. Optimal conditions (15 wt% catalyst, 120 °C, 4 h, 1:11 m ratio) yielded 92 and 90% conversions for lauric acid and the 150–190 °C fraction, respectively. However, the 195–220 °C fraction showed lower reactivity owing to reduced C12 content. These findings highlight TPA/Nb 2 O 5 as a promising catalyst for producing bio‐kerosene from distilled coconut oil fractions, advancing green chemistry in biofuel synthesis.