Time-resolved in situ visualization of the structural response of zeolites during catalysis

• Published in: Nature communications 2020-11, Vol.11 (1)
• Main Authors: Kang, Jinback, Carnis, Jerome, Kim, Dongjin, Chung, Myungwoo, Kim, Jaeseung, Yun, Kyuseok, An, Gukil, Cha, Wonsuk, Harder, Ross, Song, Sanghoon, Sikorski, Marcin, Robert, Aymeric, Thanh, Nguyen Huu, Lee, Heeju, Choi, Yong Nam, Huang, Xiaojing, Chu, Yong S., Clark, Jesse N., Song, Mee Kyung, Yoon, Kyung Byung, Robinson, Ian K., Kim, Hyunjung
• Format: Article
• Language: English
• Subjects: characterization and analytical techniques; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; imaging techniques; MATERIALS SCIENCE; porous materials; structural properties
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-020-19728-3

Zeolites form an important class of materials that are widely used in various fields. Their unique properties come primarily from their size, shape, and connectivity of their sub-nm crystalline voids, the Si/Al ratio of the anionic framework, and the number and the nature of charge-balancing cations.The inhomogeneous distribution of the Si/Al ratio within crystals, and hence the cation density, the presence of organic residues, and their inhomogeneous distribution within crystals sensitively affect their performances because these factors influencethe intra-crystalline diffusion rates of the reactants and products. However, the information regarding these inhomogeneities in zeolite crystals cannot be obtained by conventional analytical tools because they only provide information regardingthe average properties of zeolite crystals. Here we employin situX-ray free electron laser-based time-resolved coherent X-ray diffraction imaging to investigate the internal deformations originating from the inhomogeneous Cu ion distributions in Cu-exchanged ZSM-5 zeolite crystals during the deoxygenation of nitrogen oxides with propene. We show that the interactions between the reactants and the active sites lead to an unusual strain distribution,which is confirmed by density functional theory simulations. Moreover, this elucidates the factors responsible for distinct active regions,which are essential to maximizing some applications with enhanced performances. These observations provide insights into the role of structural inhomogeneity in zeolites during a catalytic processand will assist the future design of zeolites for their applications.