P改性对Mo-Ni/Al_2O_3煤焦油加氢脱氮性能的影响

Effect of phosphorus modification on the catalytic properties of Mo-Ni/Al_2O_3 in the hydrodenitrogenation of coal tar

在磷含量1.34%下,采用分步浸渍法按磷添加顺序不同制备了3种改性催化剂：Mo P-Ni/Al2O3、Mo-Ni P/Al2O3、MoNi/PAl2O3。通过X射线衍射（XRD）、程序升温脱附（NH3-TPD）、程序升温还原（H2-TPR）、氮气吸附等技术对催化剂进行了表征。以新疆中低温煤焦油为原料,考察了不同磷改性方式对催化剂加氢脱氮（HDN）性能的影响。结果表明,适宜的磷添加方式能够改变催化剂的酸性分布,提高10-13 nm加氢脱氮有效孔的比例,并且减弱活性组分与载体的相互作用,同时使得活性组分更易被还原,进而提高催化剂加氢脱氮性能。加氢脱氮活性顺序为Mo-Ni/PAl2O3（74.36%）〉Mo-Ni P/Al2O3（72.74%）〉Mo-Ni/Al2O3（71.72%）〉Mo P-Ni/Al2O3（56.13%）。

Mo-Ni/Al2O3 catalysts were modified with phosphorus by using the impregnation method. By changing the addition sequence of phosphorus,three types of catalysts,viz. Mo P-Ni/Al2O3,Mo-Ni P/Al2O3 and Mo-Ni/PAl2O3,were obtained with a P loading of 1. 34%. These catalysts were characterized by X-ray diffraction,temperature-programmed desorption of NH3,temperature-programmed reduction by H2 and N2sorption experiment. The catalytic properties of these catalysts were investigated with the hydrodenitrogenation（HDN） of low-and middle-temperature coal tar obtained from Xinjiang province. It was shown that appropriate P addition sequence can alter acid site distributions,increase the proportion of effective pores betw een 10 and13 nm,w eaken the interaction of the support and active metal components and make the reduction of the active components easier,consequently,improving the catalytic performance. The HDN activity of the three types of catalysts decreased in the order of Mo-Ni/PAl2O3（74. 36%） Mo-NiP/Al2O3（72. 74%） Mo-Ni/Al2O3（56. 13%） MoP-Ni/Al2O3（71. 72%）.