H/D Exchange of Propane on Indium-Modified Zeolite BEA Investigated by 1H MAS NMR In Situ Full article
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The Journal of Physical Chemistry C
ISSN: 1932-7447 , E-ISSN: 1932-7455 |
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| Output data | Year: 2022, Volume: 126, Number: 46, Pages: 19766–19775 Pages count : 10 DOI: 10.1021/acs.jpcc.2c06618 | ||||
| Tags | Alkyls, Hydrogen, Kinetic parameters, Kinetics, Zeolites | ||||
| Authors |
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| Affiliations |
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Funding (1)
| 1 | Russian Science Foundation | 22-13-00029 |
Abstract:
The pathways of propane molecule activation on indium-modified zeolite have been studied by 1H MAS NMR spectroscopy in situ at temperatures of 453–573 K. The kinetics of H/D hydrogen exchange between propane-d8 and Brønsted acid sites (BAS) of the H-BEA zeolite, modified with indium species in the form of either InO+ or In+ cations (InO+/H-BEA and In+/H-BEA samples), were monitored. It is shown that the presence of either InO+ or In+ species in zeolite pores provides regioselectivity of the H/D exchange in methyl groups of the propane molecule. For the InO+/H-BEA zeolite, the process is characterized by greater rates and a lower activation energy compared to those for the unmodified H-form zeolite. The two-exponential kinetics of the exchange for InO+/H-BEA is rationalized in terms of two mechanisms: a direct mechanism assisted by the InO+ species and an indirect mechanism initiated by a propene intermediate. Both mechanisms provide the regioselectivity of the exchange and low activation energy. In+/H-BEA zeolite demonstrates less activity with regard to the rate of the exchange, but it shows a lower activation energy compared to H-BEA zeolite. It is inferred, for In+/H-BEA, that the mechanism of the direct regioselective exchange competes for the same BAS with the mechanism of unselective H/D exchange. The latter results in a specific growth of protium concentration in the methyl and methylene groups of propane-d8 upon the increase of the reaction temperature.
Cite:
Arzumanov S.S.
, Gabrienko A.A.
, Toktarev A.V.
, Freude D.
, Haase J.
, Stepanov A.G.
H/D Exchange of Propane on Indium-Modified Zeolite BEA Investigated by 1H MAS NMR In Situ
The Journal of Physical Chemistry C. 2022. V.126. N46. P.19766–19775. DOI: 10.1021/acs.jpcc.2c06618 WOS Scopus РИНЦ AN OpenAlex
H/D Exchange of Propane on Indium-Modified Zeolite BEA Investigated by 1H MAS NMR In Situ
The Journal of Physical Chemistry C. 2022. V.126. N46. P.19766–19775. DOI: 10.1021/acs.jpcc.2c06618 WOS Scopus РИНЦ AN OpenAlex
Dates:
| Submitted: | Sep 16, 2022 |
| Accepted: | Oct 17, 2022 |
| Published online: | Nov 9, 2022 |
| Published print: | Nov 24, 2022 |
Identifiers:
| Web of science: | WOS:000885260400001 |
| Scopus: | 2-s2.0-85141947174 |
| Elibrary: | 50300333 |
| Chemical Abstracts: | 2022:2825943 |
| OpenAlex: | W4308736183 |