混捏法制备的Ni-Mo／γ-Al_2O_3加氢催化剂中活性组分存在状态的研究

STUDY ON THE STATE OF Ni AND Mo IN Ni Mo/γ-Al 2O 3 CATALYST

利用ＸＲＤ、ＴＥＭ、ＵＶ－漫反射光谱分析等手段，探讨了混捏法制备的Ｎｉ－Ｍｏ／γ－Ａｌ２Ｏ３催化剂中活性组分的存在状态及其随Ｎｉ、Ｍｏ原子比ρ和焙烧温度Ｔ变化而变化的情况。结合样品的加氢活性测定结果，得出样品表面上的新相ｘＮｉＯ·ｙＭｏＯ３·ｚＨ２Ｏ的相对含量的变化规律以及表面八面体配位状态Ｎｉ〔Ｏ〕的相对含量的变化规律与样品加氢活性的变化规律相同。研究认为，新相ｘＮｉＯ·ｙＭｏＯ３·ｚＨ２Ｏ为Ｎｉ－Ｍｏ／γ－Ａｌ２Ｏ３催化剂的活性相，ｘＮｉＯ－ｙＭｏＯ３·ｚＨ２Ｏ中的Ｎｉ为八面体配位状态的Ｎｉ。

By means of X ray diffraction (XRD),transmission electron microscopy (TEM) and UV visible diffuse reflection spectronscopy (DRS),the state of active components of the kneading prepared catalyst Ni Mo/γ Al 2O 3 was studied.The relation between catalytic acti vity of hydrogenation and the state of active components was also investigated.The experimental results show that nickel(Ni) and molybdenum (Mo) are entirely dispersed on the surface of γ Al 2O 3,and the active components of Ni and Mo existed as the phases of MoO 3,δ NiAl 26 O 40 ,NiAl 2O 4,NiMoO 4 and xNiO·yMoO 3·zH 2O.The relative content of each phase varies with the atomic ratio of Ni and Mo and the calcination temperature.When the atomic ratio of Ni and Mo is 0 4 and the calcination temperature to be 550℃,the relative content of the xNiO·yMoO 3·zH 2O phase reaches its maximum,so does the relative content of the octahedral Ni (Ni O ) with further study of Ni coordinate state.The hydrogenation activity evaluation also show that the variation of relative contents of xNiO·yMoO 3·zH 2O and Ni O phases has the same trend as the hydrogenation activity.As a result,xNiO·yMoO 3·zH 2O phase is supposed to be the active phase in which Ni is in the octahedral coordinated state.