Direct imaging of atomically dispersed Mo enables locating Al in the framework of zeolite ZSM-5.
KAUST DepartmentAdvanced Membranes and Porous Materials Research Center
Chemical Science Program
King Abdullah University of Science and Technology (KAUST), Physical Sciences and Engineering Division, Advanced Membranes and Porous Materials (AMPM) Center, Thuwal 23955-6900, Saudi Arabia, SAUDI ARABIA.
Nanostructured Functional Materials (NFM) laboratory
Physical Science and Engineering (PSE) Division
KAUST Grant NumberFCC/1/1972-19
Online Publication Date2019-11-05
Print Publication Date2020-01-07
Embargo End Date2020-11-06
Permanent link to this recordhttp://hdl.handle.net/10754/660219
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AbstractZeolites often act as host materials to encapsulate guest molecules to enrich their functions and applications, particularly in heterogeneous catalysis. Unfortunately, directly imaging guest molecules residing in the intact microporous structure of a zeolite has long been a challenge. Here, we report that integrated differential phase-contrast scanning transmission electron microscopy (iDPC-STEM) is capable of directly probing guest molecules in zeolites, due to its sufficient and interpretable image contrast for both heavy and light elements under low-dose conditions. We first demonstrate this unique ability by imaging volatile organic compounds adsorbed in zeolite Silicalite-1; we then use iDPC-STEM to investigate molybdenum supported on various zeolites including Silicalite-1, ZSM-5, and mordenite. We observe isolated single-Mo clusters in the micropores of ZSM-5, and demonstrate the crucial role of framework Al in driving Mo atomically dispersed into the micropores. Importantly, the specific one-to-one Mo-Al interaction makes it possible to locate Al atoms, i.e. catalytic active sites, in the ZSM-5 framework from the images, according to the positions of Mo atoms in the micropores. Our results indicate the feasibility of directly imaging guest components in fragile crystals at atomic resolution, paving the way to investigate host-guest interactions in nanoporous materials in unprecedented detail.
CitationLiu, L., Wang, N., Zhu, C., Liu, X., Zhu, Y., Guo, P., … Han, Y. (2019). Direct imaging of atomically dispersed Mo enables locating Al in the framework of zeolite ZSM-5. Angewandte Chemie International Edition. doi:10.1002/anie.201909834
SponsorsThis research was supported by CCF grant(FCC/1/1972-19) to Y.H. from King Abdullah University of Science and Technology (KAUST). This research used the resources of KAUST’s Core Labs facilities.Y. Z.acknowledges financial support from National Natural Science Foundation of China (21771161) and the Thousand Talents Program for Distinguished Young Scholars. D. Z.acknowledges financial support from Fundamental Research Funds for the Central Universities (02200052020013).