EXAFS研究加氢处理催化剂载体中Y型分子筛对催化性能的影响

EXAFS Studies of Influence of Y-type Zeolite on Hydrotreated Catalysts

运用广延X射线吸收精细结构技术对经Y型分子筛改性前、后的加氢处理催化剂Ni W γ Al2 O3样品的W的LⅢ吸收边和Ni的K吸收边进行了结构分析。结果发现 ,经Y型分子筛改性后的催化剂Ni W γ Al2 O3体系中活性组分Ni和W的局域原子环境有所变化 :催化剂中组分的八面体结构变得松散 ,W—O键较弱 ,O易于在加氢脱硫反应中被替代 ,而催化剂表面金属Ni组分浓度略有增加 。

The Ni W hydrotreated catalysts based on γ Al 2O 3 support and γ Al 2O 3+Y zeolite were studied with extended X ray absorption fine structure (EXAFS).The EXAFS results at Ni 1 s and W 2 p 3/2 edges show that addition of Y zeolite significantly changes the local atomic environment around Ni and W atoms in the active component of the Ni W γ Al 2O 3 system,and also enhances the hydrodesulphurization (HDS) of the catalysts.In the samples containing Y zeolite,the W atoms with an octahedral structure tend to be much less compact;the W—O bonding is weaker and oxygen atom may easily be substituted by a sulfur atom in HDS reaction.The surface concentration of Ni considerably increases.We suggest that the catalysts modified by adding Y zeolite may strongly promote HDS activity.