Waste-derived, plant-mediated γ-Al2O3 introduced with nickel as mesoporous catalysts for microwave-assisted conversion of Calophyllum inophyllum L. oil to jet biofuel

Transforming waste into functional catalysts represents a strategy for resource valorization. Herein, waste laboratory aluminum foil was used as a precursor for preparing mesoporous γ-Al 2 O 3 , while Sapindus rarak extract, rich in phenolics and saponins, was utilized as a plant-derived additive to tailor its physicochemical properties. The γ-Al 2 O 3 materials were screened based on textural properties, acidity, and catalytic performance. A-10, prepared using 10% (v/v) Sapindus rarak extract, exhibited the highest BET surface area (190.33 m 2 g −1 ), total pore volume (0.37 cm 3 g −1 ), average pore diameter (3.90 nm), and total acidity (1.50 mmol NH 3 g −1 ), affording a jet biofuel yield of 30.15 wt% during microwave-assisted atmospheric pressure hydroconversion of Calophyllum inophyllum L. oil (550 °C, 30 min, 20 mL min −1 H 2 , feed/catalyst 100). A-10 was selected for Ni loading in the presence of oxalic and citric acids by an ultrasound-assisted wet method, and Ni/γ-Al 2 O 3 catalysts with different Ni contents were evaluated. Ni 5/A-10 (5 wt% Ni) afforded the highest jet biofuel yield of 54.56 wt%. GC–MS and PIONA analyses showed that paraffins predominated in the C 8 –C 16 fraction, indicating that oxygen-removal followed by hydrocracking promoted jet fuel-range hydrocarbon formation. Ni 5/A-10 maintained catalytic performance without regeneration, with a jet biofuel yield of 35.88 wt% after the third reuse cycle. Spent-catalyst characterization indicated that deactivation was associated with carbon-containing deposits rather than structural collapse of the γ-Al 2 O 3 framework. Collectively, these findings provide insights into γ-Al 2 O 3 -based catalyst design for jet biofuel production.