NiW/Al_2O_3催化剂酸性与加氢活性的调变及对重油加氢脱氮性能的影响

以Ni、W为催化剂的活性金属组分,采用等体积浸渍法制备了NiW/Al2O3加氢脱氮催化剂,考察了Al2O3载体表面经硼酸修饰后对催化剂酸性的影响,以及活性金属与柠檬酸络合后对催化剂加氢反应性能的影响。NH3-TPD、HRTEM、H2-TPR、XPS等表征结果表明,Al2O3载体表面硼酸修饰增加了催化剂表面的中强酸量,减少了强酸量,且削弱了金属与载体之间的强相互作用,但活性中心数目减少。金属与柠檬酸络合可以减小活性相晶粒长度、提高活性相分散性及硫化程度。催化剂的反应评价结果表明,硼酸修饰与柠檬酸络合共同作用可以增强催化剂的重油加氢处理能力,促进芳环与胶质的加氢饱和;具有适宜的氢解与加氢活性,兼顾碱性氮与非碱性氮的脱除,体现了催化剂良好的重油加氢脱氮性能。

Effect of acidity and hydrogenation ability on the hydrodenitrogenation performance of NiW/Al2 O3 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.