Citric acid-assisted hydrothermal method for preparing NiW/USY-Al2O3 ultradeep hydrodesulfurization catalysts

► Citric acid-assisted hydrothermal system enhances the dispersion of active metals. ► This hydrothermal system finely tunes the acidity and pore structure of HY zeolite. ► These two effects endow the catalyst with outstanding hydrodesulfurization activity.