Mo-Ni-γ-Al2O3体系中Mo、Ni近邻结构的EXAFS研究

运用EXAFS技术对加入P2O5或TiO2的MO-Ni-γ-Al2O3体系中Mo、Ni的K吸收边进行了分析，获得了体系中金属组分原子周围的微观结构信息，从而进一步证实P或Ti的加入有助于含量较高的Mo、Ni在载体表面的高度分散，样品中适量的P有助于形成较多的八面体结构，所有含P的样品中八面体结构含量均高于含Ti的样品，八面体结构Mo-O键上的氧在加氢脱硫反应中较易被硫取代，因而提高反应活性，这是含八面体结构较多的MoNiP样品的加氢脱硫活性优于MoNiTi样品的一个重要原因.

EXAFS Studies on the Local Structure of Ni and Mo in Nickel-molybdenum Catalyst System

The local structure surrounding Mo and Ni atoms in a series of nickel-molybdenum-γ-Al2O3 catalysts promoted by P2O5 or TiO2 was investigated using EXAFS technique at Mo and Ni 1s edge. The analysis results show that the addition of P or Ti increases the metal dispersion under the condition of high Mo content and the octahedral structure in MoNiP catalysts is more abundant than that in MoNiTi. Moderate content of P2O5 facilitates the formation of the octahedral structure. It is also found that oxygen atoms of Mo-O bond in octahedral structure are easy to be substituted by S in hydrodesulphurization(HDS) reaction. In MoNiP catalysts the higher HDS activity might be caused by the abundance of octahedral structure.