Radboud University of Nijmegen, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
Solid State Nucl Magn Reson. 2011 May-Jun;39(3-4):99-105. doi: 10.1016/j.ssnmr.2011.04.008. Epub 2011 May 6.
The role of extra-framework and framework aluminium in wet-ion exchanged Fe-ZSM5 has been studied using (29)Si NMR and (27)Al triple quantum magic angle spinning (3QMAS) NMR. A series of samples were studied, the parent material, the wet ion exchanged Fe-ZSM5 and Fe-ZSM5 that has been used in the decomposition of N(2)O with varying reaction conditions. Various framework and extra-framework aluminium species have been identified. It was found that cationic Fe species prefer to replace the Brønsted acid protons in their charge balancing role at those aluminium sites associated with the largest quadrupolar product. The framework aluminium atoms that pertain to the smaller quadrupolar product, which are either charge balanced by extra-framework aluminium or a proton, are much less prone to exchange. In the catalytic decomposition of N(2)O it seemed that water present in small amounts enhances the catalytic activity. However, water also decreases the long term stability and performance by dealuminating the zeolite framework. With a high amount of water present, Fe-ZSM5 was destabilised and catalytically inferior.
使用（29）Si NMR 和（27）Al 三量子魔角旋转（3QMAS）NMR 研究了在湿离子交换 Fe-ZSM5 中骨架外和骨架铝的作用。研究了一系列样品，包括母体材料、湿离子交换 Fe-ZSM5 和在不同反应条件下用于分解 N（2）O 的 Fe-ZSM5。已经鉴定出各种骨架和骨架外铝物种。结果发现，在与最大四极矩乘积相关的那些铝位上，带正电荷的 Fe 物种倾向于取代 Brønsted 酸质子，以起到电荷平衡作用。与较小四极矩乘积相关的骨架铝原子，要么通过骨架外铝或质子平衡电荷，就不太容易发生交换。在 N（2）O 的催化分解中，少量存在的水似乎可以提高催化活性。然而，水也通过脱铝作用降低了沸石骨架的长期稳定性和性能。当存在大量水时，Fe-ZSM5 变得不稳定，催化性能较差。
