用EXAFS研究NiO/α-Al2O3催化剂的结构和相含量

采用EXAFS方法研究了工业上使用的NiO/α-Al_2O_3催化剂反应前后的结构和相组成。催化剂反应后部分NiO还原成Ni, 在反应塔不同高度还原的量不同。用分析混合相的EXAFS方法测定了NiO和Ni的含量, 并给出了Ni原子在两相中的近邻结构参数。结果表明, 还原出的Ni原子平均配位数较少, 是Ni原子以较多比例处于表面而引起, 估计了这些集合体的尺寸。而NiO中的Ni原子近邻参数反应前后没有明显变化。

THE STUDY OF STRUCTURE AND PHASE CONTENT IN NiO/α-Al2O3 CATALYST BY EXAFS

The structure and phase content in industrial catalyst NiO/α-Al_2O_3 before and after reaction were studied by EXAFS. Part of NiO in the catalyst is reduced to Ni phase. The reducing amount is different for the samples located at different height of the reactor. The phase contents of NiO and Ni were measured and the local structure around Ni atoms was measured by using mixed phase EXAFS analysis method. The results show that the average coordination number of Ni atom in Ni phase is decreased compared with metal Ni. This is caused by more Ni atoms located at surface state. The dimension of Ni cluster is estimated. Meanwhile there is no obvious change of the environment of Ni atom in NiO phase before and after reaction.