Issue 12, 2018

Zeolites with isolated-framework and oligomeric-extraframework hafnium species characterized with pair distribution function analysis

Abstract

Zeolites containing framework heteroatoms (e.g., Ti, Sn, and Hf) with open coordination sites behave as solid-state Lewis acids and exhibit remarkable catalytic properties unachievable with bulk oxides. However, direct evidence confirming the incorporation of such heteroatom species into the zeolite framework is difficult to obtain because of the limited number of analytical methods capable of discerning framework incorporation from extraframework species. In this work, the structural environments of hafnium (Hf) framework and extraframework species added post-synthetically into *BEA zeolites were analyzed using coupled pair distribution function (PDF) and diffuse reflectance (DR) UV-vis measurements. PDF analysis enabled the visualization and identification of framework and extraframework HfOx species, both of which were undetectable by traditional X-ray and neutron diffraction methods. Reactivity data from the aldol condensation of benzaldehyde and acetone confirmed that framework Hf species are responsible for catalytic activity.

Graphical abstract: Zeolites with isolated-framework and oligomeric-extraframework hafnium species characterized with pair distribution function analysis

Supplementary files

Article information

Article type
Communication
Submitted
22 Jan 2018
Accepted
01 Mär 2018
First published
02 Mär 2018

Phys. Chem. Chem. Phys., 2018,20, 7914-7919

Author version available

Zeolites with isolated-framework and oligomeric-extraframework hafnium species characterized with pair distribution function analysis

T. Iida, K. Ohara, Y. Román-Leshkov and T. Wakihara, Phys. Chem. Chem. Phys., 2018, 20, 7914 DOI: 10.1039/C8CP00464A

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