Effect of metal element modification on the hydrothermal stability of Y zeolite
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摘要: 采用X射线粉末衍射（XRD）、固体核磁共振（MAS NMR）、扫描电镜（SEM）等分析手段研究了金属离子（Y、Ga、Cr、Zn、Cu）对Y型分子筛水热稳定性的影响。结果表明，金属离子Y的引入能抑制Y型分子筛晶胞收缩，避免骨架铝的脱除，显著提高了分子筛的水热稳定性；金属离子Zn、Cu的引入在一定程度上能较好地稳定分子筛骨架结构，但是其耐高温水热性能较差，经过800℃水热处理后，分子筛的骨架结构基本倒塌；金属离子Ga、Cr不同于Y、Zn、Cu，不能很好地稳定分子筛骨架结构，其耐高温水热性能介于两者之间。Abstract: The effect of metal element (Y, Ga, Cr, Zn and Cu) modification on the hydrothermal stability of Y zeolite was studied by X-ray diffraction (XRD), solid-state NMR spectroscopy (MAS NMR) and scan electron microscopy (SEM). The results showed that the introduction of yttrium element can suppress the condensation of unite cell and the formation of extra-framework alumina and hence remarkably enhance the hydrothermal stability of Y zeolite. The introduction of zinc or copper can also strengthen the stability of Y zeolite to some extent, however, the framework structure of Y zeolite modified by zinc or copper may be destroyed heavily by high temperature (800℃) steam treatment. Unlike yttrium, zinc and copper, gallium or chromium element can not stabilize the structure of Y zeolite, but the hydrothermal stability of Y zeolite modified by gallium or chromium lies between that of Zn/Cu-modified zeolites and that of Y-modified zeolite.
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Key words:
- Y zeolite /
- hydrothermal stability /
- metal element /
- modification /
- structure
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