Microwave- Assisted Synthesized Ni/ZSM-5 Nanocatalysts for High-Efficiency Atmospheric Hydrotreatment of Palm Oil Based Bio-Jet Fuel

This study reports the synthesis of Ni/ZSM-5 catalysts via a combined spray-dry impregnation and aging process assisted by microwave irradiation to enhance textural and acidic properties for the hydrotreatment of palm oil into bio-jet fuel. Compared with conventional thermal synthesis, the microwave-assisted route provides rapid and homogeneous volumetric heating, which strengthens metal–support interactions, improves Ni dispersion, and minimizes pore blockage during precursor decomposition. The physicochemical properties of the catalysts were systematically characterized using FTIR, XRD, SAA, SEM–EDX, XRF, NH₃-TPD, XPS, TEM, and TGA, while the product distribution was analyzed by GC–MS. Consequently, the microwave-synthesized Ni/Z MW catalyst exhibits a higher specific surface area of 238.81 m² g⁻¹ and an increased total pore volume of 0.21 cm³ g⁻¹, surpassing both parent ZSM-5 and conventionally prepared Ni/Z C catalysts. Furthermore, Ni/Z MW demonstrates an optimized acidity profile, with weak, medium, and strong acid site densities of 0.664, 0.945, and 0.201 mmol g⁻¹, respectively, corresponding to a total acidity of 1.810 mmol g⁻¹, where the dominance of medium and strong acid sites favors hydrocracking pathways. Under hydrotreatment conditions at atmospheric pressure and 400–450°C, the Ni/Z MW catalyst achieves a superior bio-jet fuel yield of 38.07% with high selectivity and excellent stability over five reuse cycles. The resulting bio-jet fuel fulfills aviation fuel specifications, including an ultra-low freezing point of − 53.19°C.