摘要
用ＸＰＳ、ＤＲＳ及Ｍｏｓｓｂａｕｅｒ谱对水热处理改性的ＦｅＺＳＭ－５中Ｆｅ（Ⅲ）的化学状态进行了研究，并定量地考察了水热处理时间对骨架铁含量的影响，比较了不同水热处理时间及不同平衡阳离子交换的ＦｅＺＳＭ－５上乙苯的吸附及扩散性质。水热处理将使骨架铁从骨架析出，但析出的骨架铁并不阻塞孔道，而是高分散在分子筛的表面上，乙苯的吸附量随水热处理时间增加而增大。阳离子交换的ＦｅＺＳＭ－５上乙苯的扩散系数及吸附量均按Ｈ、Ｌｉ、Ｎａ、Ｋ离子半径增大的顺序递减。乙苯的氧化脱氢活性主要取决于Ｆｅ（Ⅲ）活性中心的性质，也与乙苯的吸附量及扩散系数有关。
The chemical states of iron(Ⅲ)in FeZSM-5 zeolites modified by hydrothermal treatment were studied by XPS,DRS and Mossbauer spectroscopic techniques.The influence of hydrothermal treating time on the amount of framework iron and nonframework iron was examined quantitatively. The adsorptive amount and efficient diffusivity of ethylbenzene over FeZSM-5 zeolites of different time for hydrothermal treatment and exchanged with different cations were also determined.The hydrothermal treatment will cause the framework iron(Ⅲ)to separate from the framework of FeZSM-5, but it highly disperses on the surface and does not plug up the pore of the zeolite. The adsorptive amount of ethylbennzene over FeZSM-5 experienced hydrothermal treatment increases with the treating time.The adsorbed amount and efficient diffusivity of ethvlbenzene over FeZSM-5 zealites modified by different exchanged cations decreases with the increase of cation diameter in the following order: H+,Li+, Na + and K+. The activity of oxydehydrogenation for ethylbenzene mainly depends on the properties of the active center Fe(Ⅲ), but it also has a direct bearing on the adsorptive amount and diffusivity of ethylbenzene.
出处
《分子催化》
EI
CAS
CSCD
1995年第5期321-328,共8页
Journal of Molecular Catalysis(China)
基金
国家自然科学基金
关键词
乙苯
吸附
扩散
沸石
改性
氧化脱氢
FeZSM-5, Ethylbenzene, Hydrothermal treatment, Exchanged Cation, Adsorption and diffusion.
