框架与局部框架结构在确定MCM-41中介结构的热水稳定性方面的作用
Thomas R Pauly1, Valeri Petkov, Yu Liu
1Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA.
Journal of the American Chemical Society
|January 5, 2002
概括
杂质显著降低了MCM-41材料的热水稳定性. 清除离子对于在恶劣条件下保持中孔结构完整性至关重要.
科学领域:
- 材料科学 材料科学 材料科学
- 纳米技术纳米技术
- 化学 化学 化学
背景情况:
- 像MCM-41这样的半孔材料对于催化和分离至关重要.
- 水热稳定性是这些材料的关键性能指标.
- 了解影响MCM-41稳定性的因素对于优化其应用至关重要.
研究的目的:
- 为了研究含量对MCM-41的热水稳定性的影响.
- 为了比较不同来源合成的MCM-41的结构性质.
- 阐明会影响中孔完整性的机制.
主要方法:
- 固态核磁共振 (NMR) 光谱,特别是 (29) Si MAS NMR. 固态核磁共振 (NMR) 光谱.
- 使用同步X射线散射数据进行对分布函数 (PDF) 分析.
- 在蒸汽下在高温下进行热水处理.
主要成果:
- 两种MCM-41材料,无论合成路径 (酸与蒸二氧化),都表现出类似的局部框架结构 (约. 80% Q ((4) 单位) 的单位.
- 含的MCM-41 (来自酸盐) 显示水热稳定性显著降低,在蒸汽暴露下,中相孔崩.
- 没有的MCM-41 (来自蒸发的二氧化) 保持了它的结构,但即使少量添加 (0.10%Na(2) O) 也会损害稳定性.
结论:
- 陷入框架的离子作为催化剂,在水热应力下在MCM-41中催化介质的崩.
- 合成前体 (酸与烟) 影响最终的含量,从而影响水热稳定性.
- 降低含量至关重要,以开发强大的MCM-41材料,适用于苛刻的应用.
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