【摘要】 采用ＭｏＯ３／ＳｉＯ２和ＮＨ３程序升温反应的方法合成了一系列不同Ｍｏ含量的Ｍｏ２Ｎ／ＳｉＯ２催化剂，并采用ＸＲＤ、ＢＥＴ、ＸＰＳ、ＴＰＲ、Ｈ２ＴＰＤ和ＩＲ等手段，结合中压下吡啶加氢脱氮反应，研究了它们的表面性质和反应性能．发现Ｍｏ２Ｎ／ＳｉＯ２催化剂在反应性能和吸氢性质等方面类似于非负载的氮化钼．氮化前后，低Ｍｏ担载量催化剂的比表面积降低不大，在高Ｍｏ担载量下，由于氮化态的Ｍｏ／ＳｉＯ２催化剂上出现了粒径更小的晶相γＭｏ２Ｎ，而使其比表面积比前身态的增加．在钝化态的Ｍｏ２Ｎ／ＳｉＯ２表面，有Ｍｏ６＋、Ｍｏ４＋和Ｍｏδ＋（０＜δ＜２）三种价态的Ｍｏ存在，其中高价钼以氮氧化物或无定形的ＭｏＯ２的形式存在，它们可在高温被还原．ＮＯ和吡啶吸附的红外结果表明，在Ｍｏ２Ｎ／ＳｉＯ２催化剂上有配位不饱和的Ｍｏ中心和Ｌ酸中心存在，它们是吡啶加氢脱氮的吸氢活性中心和脱氮活性中心．更多还原

【Abstract】 A series of SiO₂ supported Mo nitrides were prepared by temperatureprogrammed reaction of supported molybdates with NH3, and they were studied by means of pyridine hydrodenitrogenation （HDN）, XRD, XPS, H₂TPD, TPR and IR techniques. The results show that the hydrogen adsorption properties and activity for pyridine HDN of Mo₂N/SiO₂ catalysts are similar to those of unsupported molybdenum nitride. XRD results show that the nitride domains in the lowloading materials are X-ray amorphous while the highloading catalysts consist of γMo₂N crystallites. Three types of Mo cations, Mo⁶+, Mo⁴+ and Moδ+ （0<δ<2）, are present on the passivated catalysts. The Mo⁶+ and Mo⁴+ cations, which present as oxynitrides or amorphous MoO₂, can be reduced at elevated temperatures. Also the results of NO and pyridine adsorbed on nitrided Mo/SiO₂ suggest that there are coordinatively unsaturated Mo sites with nitrogen deficiency and Lewis acid sites on the catalysts. Those active sites are contributed to the hydrogenation and CN bond cleavage in pyridine HDN reaction. 更多还原