Pinpointing and Quantifying the Aluminum Distribution in Zeolite Catalysts Using Anomalous Scattering at the Al Absorption Edge,Journal of the American Chemical Society

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Pinpointing and Quantifying the Aluminum Distribution in Zeolite Catalysts Using Anomalous Scattering at the Al Absorption Edge
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2021-10-25 , DOI: 10.1021/jacs.1c06925
Ana B Pinar ₁ , Przemyslaw Rzepka _{1,

2} , Amy J Knorpp ₂ , Lynne B McCusker ₃ , Christian Baerlocher ₂ , Thomas Huthwelker ₄ , Jeroen A van Bokhoven _{1,

2}

Affiliation

The location of aluminum in a zeolite framework structure defines the accessibility and geometry of the catalytically active sites, but determining this location crystallographically is fraught with difficulties. Typical zeolite catalysts contain only a small amount of aluminum, and the X-ray scattering factors for silicon and aluminum are very similar. To address this problem, we have exploited the properties of resonant X-ray powder diffraction across the Al K edge, where the aluminum scattering factor changes dramatically. By combining conventional synchrotron powder diffraction data with those collected at energies near the X-ray absorption edge, aluminum is highlighted. In this way, the different distributions of aluminum in two FER-type zeolites with identical chemical compositions but different catalytic properties could be determined unambiguously. The results are consistent with previous studies, but quantitative. This approach constitutes a major advance in our fundamental understanding of the relationship between zeolite structure and catalytic activity.

中文翻译：

使用铝吸收边缘的异常散射精确定位和量化沸石催化剂中铝的分布

铝在沸石骨架结构中的位置决定了催化活性位点的可及性和几何形状，但从晶体学上确定该位置充满困难。典型的沸石催化剂仅含有少量铝，硅和铝的 X 射线散射因子非常相似。为了解决这个问题，我们利用了铝 K 边缘共振 X 射线粉末衍射的特性，其中铝散射因子发生了显着变化。通过将传统的同步加速器粉末衍射数据与在 X 射线吸收边缘附近的能量收集的数据相结合，铝被突出显示。通过这种方式，可以明确地确定铝在两种化学成分相同但催化性能不同的 FER 型沸石中的不同分布。结果与以前的研究一致，但定量。这种方法构成了我们对沸石结构和催化活性之间关系的基本理解的重大进步。

更新日期：2021-11-03

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