Na2O及其引入顺序对Ni-Mo/MCM-41催化剂加氢脱硫性能的影响

 采用不同顺序将Na2O引入到NiMo/MCM-41催化剂前驱体中，并以质量分数0.8 %的二苯并噻吩（DBT）的十氢萘溶液作模型化合物，考察了催化剂的加氢脱硫（HDS）催化性能。结果表明，引入Na2O促进了NiMo/MCM-41催化剂前驱体中 -NiMoO4 物种的生成，不利于活性组分的分散，同时还抑制了其还原。分步浸渍法引入Na2O影响了催化剂中Mo物种的配位状态。Na2O引入顺序对NiMo/MCM-41催化剂HDS催化活性有较大影响。共浸渍法引入Na2O时，同时抑制了催化剂的加氢反应路径（HYD）和直接脱硫反应路径（DDS）催化活性，因此其HDS催化活性最低。与共浸渍和在活性组分之后引入Na2O相比，在活性组分之前引入Na2O对催化剂的HYD催化活性影响最小，但DDS催化活性显著增加，提高了总的HDS催化活性。通过控制碱金属氧化物的引入顺序，可以调变催化剂活性和选择性，是一种对硫化物催化剂有效的改性方法。

INFLUENCE OF Na2O AND ITS INTRODUCTION SEQUENCE ON THE HYDRODESULFURIZATION PERFORMANCE OF Ni-Mo/MCM-41

Na2O was introduced to NiMo/MCM-41 catalyst precursor by different sequences, and the hydrodesulfurization (HDS) performances of the prepared catalysts were studied by using a model fuel of decalin solution containing 0.8 % DBT. The results indicated that the introduction of Na2O not only facilitated the formation of -NiMoO4, leading to decreased dispersion of active species, but also suppressed the reducibility of NiMo/MCM-41 precursor. The coordination states of Mo species were affected by Na2O introduced by the consecutive impregnation methods. The HDS activity of NiMo/MCM-41 was strongly affected by the Na2O introduction sequence. For the catalyst in which Na2O was introduced by a co-impregnation method, both the activities of the hydrogenation pathway (HYD) and direct desulfurization pathway (DDS) were suppressed, resulting in a decrease in the overall HDS activity. Compared with the co-impregnation and the introduction of Na2O after NiMo active components, the addition of Na2O before the deposition of these active components showed a much less influence on the HYD activity, but significantly enhanced DDS activity of NiMo/MCM-41, thus an improvement in the overall HDS activity was observed. Both the activity and selectivity of the sulfide catalysts can be modified by adapting a proper addition sequence of the alkali-metal oxides, which is an effective way for the modification of HDS catalysts.