Time-Resolved in Situ Visualization of the Structural Response of Zeolites During Catalysis
Jinback Kang, Department of Physics, Sogang University
Jerome Carnis, Department of Physics, Sogang University
Dongjin Kim, Department of Physics, Sogang University
Myungwoo Chung, Department of Physics, Sogang University, Seoul
Jaeseung Kim, Department of Physics, Sogang University
Kyuseok Yun, Department of Physics, Sogang University
Gukil An, Department of Physics, Sogang University
Wonsuk Cha, Materials Science Division, Argonne National Laboratory
Ross Harder, Advanced Photon Source, Argonne National Laboratory
Sanghoon Song, Linac Coherent Light Source, SLAC National Accelerator Laboratory
Marcin Sikorski, Linac Coherent Light Source, SLAC National Accelerator Laboratory
Aymeric Robert, Linac Coherent Light Source, SLAC National Accelerator Laboratory
Nguyen Huu Thanh, Department of Chemistry, Sogang University
Heeju Lee, Department of Physics, Sogang University
Yong Nam Choi, Korea Atomic Energy Research Institute
Xiaojing Huang, National Synchrotron Light Source II (NSLS-II), Brookhaven National Laboratory
Yong S. Chu, National Synchrotron Light Source II (NSLS-II), Brookhaven National Laboratory
Jesse N. Clark, Stanford PULSE Institute, SLAC National Accelerator Laboratory
Mee Kyung Song, Department of Chemistry, Sogang University
Kyung Byung Yoon, Department of Chemistry, Sogang University
Ian K. Robinson, London Centre for Nanotechnology, University College London
Hyunjung Kim, Department of Physics, Sogang University
Abstract
Zeolites are three-dimensional aluminosilicates having unique properties from the size and connectivity of their sub-nanometer pores, the Si/Al ratio of the anionic framework, and the charge-balancing cations. The inhomogeneous distribution of the cations affects their catalytic performances because it influences the intra-crystalline diffusion rates of the reactants and products. However, the structural deformation regarding inhomogeneous active regions during the catalysis is not yet observed by conventional analytical tools. Here we employ in situ X-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, confirmed by density functional theory simulations. These observations provide insights into the role of structural inhomogeneity in zeolites during catalysis and will assist the future design of zeolites for their applications.
