Mo系催化剂的酸度、TPR特性与加氢脱氮性能

Studies on the Acidity, TPR Properties and HDN Activity of Mo Catalysts

采用吡啶吸附法及TPR研究了Mo-Ni-Al_2O_3催化剂的组成对酸度、还原特性及脱氮性能的影响。实验表明,催化剂的加氢脱氮性能与其所具有的中、强酸酸度及低温还原的MoO_3量有关。在MoO_3/Al_2O_3体系中,加入助剂NiO可提高中、强酸酸度,降低易还原MoO_3的还原温度,增加低温还原量;在γ-Al_2O_3上单浸Mo或Ni,易生成Al_2(MoO_4)_3和NiAl_2O_4,这两种物相对氮杂环脱氮不利。选择合适的Mo、Ni含量,可减少上述两种物相的生成,并得到适宜的酸度,有利于提高催化剂的脱氮性能。

In this paper the effects of composition of NiO-MoO_3 hydrotreating catalysts on acidity, reducing properties and HDN (hydrodenitrogenation) activity are studied by pyridine chemisorption and TPR. The experiments show the HDN activity of NiO-MoO_3 catalysts is related to the acidity of its middling acid. Addition of promoter NiO to a MoO_3 catalyst system increases the acidity of the middling acid and the amount of MoO_3 reduced at low temperature, but decreases the acidity of weaker acid and the reducing temperature of MoO_3. If NiO or MoO_3 is impregnated over Al_2O_3 alone, NiAl_2O_4 or Al_2(MoO_4)_3 phase which is inactive for HDN will form separately. Appropriate contents of NiO and M0O_3 will decrease the formation of A1_2(MoO_4)_3 and NiAl_2O_4, and suitable acidity will be obtained. All these will increase the HDN activity of NiO-MoO_3 catalysts.