Attila Özgün, King Helen E, Meirer Florian, Weckhuysen Bert M
Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht, The Netherlands.
Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Princetonlaan 8a, 3584 CB, Utrecht, The Netherlands.
Chemistry. 2019 May 23;25(29):7158-7167. doi: 10.1002/chem.201805664. Epub 2019 May 2.
Hydrothermal treatment is a common method used to modify the physicochemical properties of zeolite-based catalyst materials. It alters the number and type of acid sites through dealumination and increases molecular diffusion by mesopore formation. Steaming also reduces the structural integrity of zeolite frameworks. In this study, Raman microscopy has been used to map large zeolite ZSM-5 crystals before and after steaming. 3D elemental maps of T-O (T: Al or Si) sites of the zeolite were obtained. The Raman active vibrational bands were determined, which are indicative of (non-) framework Al, as well as of structural integrity. Zeolite steaming caused the introduction of additional heterogeneities within the zeolite framework. Al migration and the formation of extra-framework Al species were observed. The described experiments demonstrate the capability of 3D Raman spectroscopy as a valuable tool to obtain information on the spatial distributions of framework elements as well as defects within a zeolite-based material.
水热处理是一种用于改变沸石基催化剂材料物理化学性质的常用方法。它通过脱铝改变酸位点的数量和类型，并通过形成介孔增加分子扩散。水热老化也会降低沸石骨架的结构完整性。在本研究中，拉曼显微镜已被用于绘制水热老化前后的大型ZSM-5沸石晶体。获得了沸石T-O（T：Al或Si）位点的三维元素图。确定了拉曼活性振动带，其指示（非）骨架Al以及结构完整性。沸石水热老化导致沸石骨架内引入了额外的不均匀性。观察到Al迁移和骨架外Al物种的形成。所描述的实验证明了三维拉曼光谱作为一种有价值的工具，可用于获取有关沸石基材料中骨架元素的空间分布以及缺陷的信息。
