Wang Huiqiu, Shen Boyuan, Chen Xiao, Xiong Hao, Wang Hongmei, Song Wenlong, Cui Chaojie, Wei Fei, Qian Weizhong
Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, 100084, Beijing, China.
Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, 199 Ren'ai Road, 215123, Suzhou, Jiangsu, PR China.
Nat Commun. 2022 May 25;13(1):2924. doi: 10.1038/s41467-022-30538-7.
The acid sites of zeolite are important local structures to control the products in the chemical conversion. However, it remains a great challenge to precisely design the structures of acid sites, since there are still lack the controllable methods to generate and identify them with a high resolution. Here, we use the lattice mismatch of the intergrown zeolite to enrich the inherent Lewis acid sites (LASs) at the interface of a mortise-tenon ZSM-5 catalyst (ZSM-5-MT) with a 90° intergrowth structure. ZSM-5-MT is formed by two perpendicular blocks that are atomically resolved by integrated differential phase contrast scanning transmission electron microscopy (iDPC-STEM). It can be revealed by various methods that novel framework-associated Al (Al) LASs are generated in ZSM-5-MT. Combining the iDPC-STEM results with other characterizations, we demonstrate that the partial missing of O atoms at interfaces results in the formation of inherent Al LASs in ZSM-5-MT. As a result, the ZSM-5-MT catalyst shows a higher selectivity of propylene and butene than the single-crystal ZSM-5 in the steady conversion of methanol. These results provide an efficient strategy to design the Lewis acidity in zeolite catalysts for tailored functions via interface engineering.
沸石的酸性位点是控制化学转化产物的重要局部结构。然而，精确设计酸性位点的结构仍然是一个巨大的挑战，因为目前仍然缺乏高分辨率生成和识别它们的可控方法。在此，我们利用共生沸石的晶格失配，在具有90°共生结构的榫卯ZSM-5催化剂（ZSM-5-MT）界面处富集固有路易斯酸位点（LASs）。ZSM-5-MT由两个相互垂直的块体组成，通过集成差分相衬扫描透射电子显微镜（iDPC-STEM）在原子水平上进行分辨。多种方法表明，ZSM-5-MT中生成了新型的与骨架相关的铝（Al）路易斯酸位点。结合iDPC-STEM结果与其他表征，我们证明界面处O原子的部分缺失导致了ZSM-5-MT中固有Al路易斯酸位点的形成。结果，在甲醇的稳态转化中，ZSM-5-MT催化剂比单晶ZSM-5表现出更高的丙烯和丁烯选择性。这些结果提供了一种有效的策略，通过界面工程设计沸石催化剂中的路易斯酸度以实现定制功能。
