用二氨酸分子和固态NMR光谱学测量石HY中的布伦斯特德酸密度
Luming Peng1, Peter J Chupas, Clare P Grey
1Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794-3400, USA.
Journal of the American Chemical Society
|September 30, 2004
概括
这项研究使用-31固态NMR与二氨酸探针绘制地图Brønsted酸部位在西奥利特HY. 它揭示了这些地点的分布和酸度,提供了对热带石结构和催化潜力的洞察.
科学领域:
- 固态NMR光谱学 固态NMR光谱学
- 材料化学 材料化学
- 催化剂是一种催化剂.
背景情况:
- 焦岩石是布伦斯特德酸位点的关键催化剂.
- 了解这些位点的分布和酸度对于催化剂设计至关重要.
- -31神奇角旋转 (31P MAS) NMR为化学环境提供了敏感的探测器.
研究的目的:
- 调查Brønsted酸位点在HY. zeolite中的酸度和空间分布.
- 为了证明二二啡探针用于表征酸盐酸度的实用性.
- 为了将探头分子的质子与位点分离距离相关联.
主要方法:
- 使用31P MAS核磁共振光谱与不同链长的二二 (Ph2P(CH2) nPPh2) 探针 (n=1,3,6).
- 采用31P 2D双量子NMR光谱仪用于光谱分配确认.
- 分析了二氨酸分子二质子化的程度,作为探针长度和负载的函数.
主要成果:
- 在使用Ph2P(CH2)6PPh2.2.的焦化物HY中,确定了至少12对Brønsted酸位,距离约9 Å,使用Ph2P(CH2)6PPh2.2.
- 通过使用Ph2P(CH2) 3PPh2.2. 确定大约六对由6 Å分离的布伦斯特德酸位点.
- 观察到最短探头 (Ph2PCH2PPh2) 的不完全二质子,表明不同酸位强度.
结论:
- 使用二氨酸探针进行的31P MAS核磁共振对绘制布伦斯特德酸位点距离和评估石中的酸度是有效的.
- 该研究量化了HY. zeolite中酸位点的数量和接近程度.
- 这种方法提供了宝贵的见解,以量身定制热带石催化剂.
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