Catalytic oleic acid hydrotreating to bio-aviation fuel over highly dispersed Ni/SAPO-11 catalysts prepared by citric acid and ethylene glycol co-assistance impregnation

A range of Ni/SAPO-11 catalysts was generated via citric acid impregnation using various solvents (water, ethanol, and ethylene glycol); these catalysts were employed to oleic acid hydrogenation for generating bio-aviation fuel. The catalysts were characterized through powder X-ray diffraction, low-temperature nitrogen adsorption–desorption, transmission electron microscopy, hydrogen temperature-programmed reduction, X-ray photoelectron spectroscopy, in-situ thermogravimetry-Fourier transform infrared, temperature-programmed desorption of ammonia, and pyridine-adsorbed infrared spectroscopy. It was observed that the type of solvent used for the preparation of catalysts influenced the Ni particle size of the catalysts. Notably, in the catalyst preparation process, citric acid as a chelating ligand and ethylene glycol as a solvent, can enhance the interaction between Ni and SAPO-11 support, leading to the formation of small nickel nanoparticles (6.7 nm), meantime with a large surface area and strong total acid content of 0.087 mmol/g. During oleic acid hydrogenation, the Ni/SAPO-11 catalyst with citric acid and ethylene glycol co-assistance impregnation exhibited excellent catalytic performance, with 99.9% conversion and 75.9% iso-alkanes (iso-C8-C18) selectivity. Particularly, to create more multibranched iso-alkanes and show stable catalytic performance after five runs.