BioChem - DOS

Self-Organization of 1-Propanol at H-ZSM-5 Brønsted Acid Sites

JACS Au

Kim, Sungmin; Lee, Mal-Soon; Camaioni, Donald M.; Gutié rrez, Oliver Y.; Glezakou, Vassiliki-Alexandra; Govind, Niranjan; Huthwelker, Thomas; Zhao, Ruixue; Rousseau, Roger; Fulton, John L.; Lercher, Johannes A.

<P>In situ Al K-edge X-ray absorption near edge structure (XANES) and Extended X-ray absorption fine structure (EXAFS) spectroscopy in conjunction with ab initio molecular dynamics (AIMD) simulations show that adsorption of 1-propanol alters the structure of the Brønsted acid site through changes in the associated aluminum-oxygen tetrahedron in zeolite H-MFI. The decreasing intensity of the pre-edge signal of the in situ Al K-edge XANES spectra with increasing 1-propanol coverage shows that Al T-sites become more symmetric as the sorbed alcohol molecules form monomers, dimers, and trimers. The adsorption of monomeric 1-propanol on Brønsted acid sites reduces the distortion of the associated Al T-site, shortens the Al-O distance, and causes the formation of a Zundel-like structure. With dimeric and trimeric alcohol clusters, the zeolite proton is fully transferred to the alcohols and the aluminum-oxygen tetrahedron becomes fully symmetric. The subtle changes in Al-K-edge XANES in the presence of sorbate structures, with the use of theory, are used to probe the local zeolite structures and provide a basis to predict the population and chemical state of the sorbed species.</P><BR>[FIG OMISSION]</BR>

2023

American Chemical Society

2691-3704

3

9

pp.2487-2497

10.1021/jacsau.3c00259

http://click.ndsl.kr/servlet/OpenAPIDetailView?keyValue=05787966&target=NART&cn=NART125614225

in situ Al K-edge XAS; TD-DFT XANES; MD-EXAFS; AIMD simulation; adsorption on H-MFI; quantitative XANES analysis