Effect of acidity and hydrogenation ability on the hydrodenitrogenation performance of NiW/Al₂O₃ catalyst

NiW/Al₂O₃ catalysts for the hydrodenitrogenation of heavy oil were prepared by nickel-tungstate active metals located on Al₂O₃ with wetness impregnation. The effect of boric acid on the acidity and the effect of citric acid on the hydrogenation ability were studied. The results of NH₃-TPD, HRTEM, H₂-TPR and XPS showed that the addition of boric acid increased the proportion of strong and medium acid. The strong interaction between the support and metal has been weakened. Citric acid achieved moderate length of Ni-W-S active phases, increased the dispersion and the sulfidation degree of the metal on catalysts surface. NiW catalyst modified with boron acid and citric acid had outstanding HDN performance for Venezuela deasphalted oil, promoted the hydrogenation of aromatics and resin. It also had strong HDN abilities to basic and non-basic nitrogen compounds. The catalyst showed outstanding HDN performance of heavy oil.