镍盐和氧化镍在NaY沸石中存在状态研究

用ＸＲＤ、ＥＸＡＦＳ和ＴＰＲ方法研究了Ｎｉ（ＮＯ３）２／ＮａＹ和ＮｉＯ／ＮａＹ分散体系。在沸石上，Ｎｉ（ＮＯ３）２的分散比ＮｉＯ容易得多。ＸＲＤ相定量方法测定的ＮｉＯ在ＮａＹ沸石上的分散阈值很低，仅为密置单层容量的２％左右。在分散阈值关ＮｉＯ在沸石上处于分散相和笼外小晶粒两种状态。分散相ＮｉＯ比笼外ＮｉＯ小晶粒难还原。样品中ＮｉＯ含量超过阈值时，笼外小晶粒长大成ＸＲＤ可检测的较大晶粒。

Studies on the Dispersion States of Nickel Salt and Oxide on NaY Zeolites

The Ni(NO3)2/NaY and NiO/NaY dispersed systems were studied by XRD,EXAFS, and TPR methods.It has been found that Ni(NO3)2 is more readily dispersed on NaY than NiO. The dispersion threshold of NiO on NaY has been determined by XRD quanitative phase analysis, and it amounts only to 2% of the close packed monolayer capacity. Before the dispersion threshold NiO on the zeolite exists as the dispersed NiO phase and small NiO crystallites outside the zeolite cage. The dispersed NiO phase is more difficult to reduce than the small NiO crystallites. As the NiO content in the sample is increased above the dispersion threshold, the small NiO crystallites outside the zeolite cage grow into larger crystallites detectable by XRD.