中国科学院大连化学物理研究所徐舒涛团队报道了MOR框架铝稳定性的固态核磁共振研究。相关研究成果发表在2024年2月20日出版的《结构化学》。

MOR沸石由于其独特的孔结构和酸性，已被有效地用于二甲醚（DME）羰基化反应。在工业生产过程中，铵型MOR沸石（NH₄-MOR）向质子型MOR分子筛（H-MOR）的转化不可避免地会导致脱铝。因此，了解沸石脱铝的影响因素和动态演化机制至关重要。

该文通过XRD、FTIR、²⁹Si、²⁷Al、¹H MAS NMR和DME羰基化性能评价对框架铝的稳定性进行了研究。研究结果表明，由于框架对水的“吸引力”不同，与H⁺相比，额外的框架阳离子Na⁺和NH₄⁺可以更好地保留MOR沸石框架的铝结构。此外，通过控制煅烧气氛的湿度，研究了高温下水对沸石框架铝的影响，揭示了框架外六配位铝（Al（VI）-EF）的形成以及水对沸石框架铝的影响机制。

附：英文原文

Title: Solid-state NMR study of the stability of MOR framework aluminum

Author: Xinzhi Ding, Chong Liu, Jing Niu, Nan Chen, Shutao Xu, Yingxu Wei, Zhongmin Liu

Issue&Volume: 2024-02-20

Abstract: MOR zeolite has been effectively utilized for dimethyl ether (DME) carbonylation reaction due to its unique pore structure and acidity. During industrial production, the transformation of ammonium type MOR zeolite (NH4-MOR) into proton type MOR zeolite (H-MOR) causes inevitable dealumination. Therefore, understanding the influencing factors and dynamic evolution mechanism of zeolite dealumination is crucial. In this work, the stability of framework aluminum was studied by XRD, FTIR, 29Si, 27Al, 1H MAS NMR, and DME carbonylation performance evaluation. These results indicated that extra-framework cation Na+ and NH4+ could better preserve the aluminum structure of the MOR zeolite framework compared to H+, primarily due to the different ‘attraction’ of the framework to water. Furthermore, the impact of water on the zeolite framework aluminum at high temperature was studied by manipulation the humidity of the calcination atmosphere, revealing the formation of extra-framework six-coordinated aluminum (Al (VI)-EF) and the mechanism of water influence on the zeolite framework aluminum.

DOI: 10.1016/j.cjsc.2024.100247

Source: http://cjsc.ac.cn/cms/issues/571