Competitive Pathways of Methane Activation on Zn2+-Modified ZSM-5 Zeolite: H/D Hydrogen Exchange with Brønsted Acid Sites: Versus Dissociative Adsorption to Form Zn-Methyl Species

Competitive Pathways of Methane Activation on Zn2+-Modified ZSM-5 Zeolite: H/D Hydrogen Exchange with Brønsted Acid Sites: Versus Dissociative Adsorption to Form Zn-Methyl Species Научная публикация

Журнал

Catalysis Science & Technology
ISSN: 2044-4761

Вых. Данные

Год: 2016, Том: 6, Номер: 16, Страницы: 6381-6388 Страниц : 8 DOI: 10.1039/c6cy00878j

Авторы

Arzumanov Sergei S. ^1,2 , Gabrienko Anton A. ^1,2 , Freude Dieter ³ , Stepanov Alexander G. ^1,2

Организации

1	Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, Prospekt Akademika Lavrentieva 5, Novosibirsk 630090, Russia
2	Department of Natural Sciences, Novosibirsk State University, Pirogova Street 2, Novosibirsk 630090, Russia
3	Fakultät für Physik und Geowissenschaften, Universität Leipzig, Linnéstraße 5, 04103 Leipzig, Germany

To clarify the pathways of methane activation on Zn-modified high-silica zeolites, the kinetics of both dissociative adsorption of the alkane C-H bond to form Zn-methyl species and H/D hydrogen exchange between the alkane and Brønsted acid sites (BAS) have been analyzed for Zn2+/H-ZSM-5 containing exclusively Zn2+ cations (no ZnO species in the zeolite) and BAS. Analysis of the kinetics was performed by 1H MAS NMR spectroscopy in situ at 410-540 K. In spite of the activation barrier for H/D hydrogen exchange (68 kJ mol-1) being larger than that for Zn-methyl formation (46 kJ mol-1), the rate of H/D hydrogen exchange has been found to be one order of magnitude higher than the rate of the formation of Zn-methyl species within the studied temperature range. This implies that Zn-methyl species cannot be involved in the reaction of H/D hydrogen exchange as the intermediate responsible for facilitation of this reaction due to the presence of Zn2+ cations in the zeolite (J. Catal., 2008, 253, 11). A new mechanism has been suggested for C-H bond activation in methane on the zeolite modified with Zn2+ cations. It includes first the formation of a transient molecular complex of methane with Zn2+ cations. The complex either is further involved in the reaction of H/D hydrogen exchange or evolves toward the formation of Zn-methyl species and BAS.

Arzumanov S.S. , Gabrienko A.A. , Freude D. , Stepanov A.G.
Competitive Pathways of Methane Activation on Zn2+-Modified ZSM-5 Zeolite: H/D Hydrogen Exchange with Brønsted Acid Sites: Versus Dissociative Adsorption to Form Zn-Methyl Species
Catalysis Science & Technology. 2016. V.6. N16. P.6381-6388. DOI: 10.1039/c6cy00878j WOS Scopus РИНЦ CAPlusCA OpenAlex Sciact

Поступила в редакцию:	21 апр. 2016 г.
Принята к публикации:	31 мая 2016 г.
Опубликована online:	31 мая 2016 г.

Web of science:	WOS:000381439400023
Scopus:	2-s2.0-84981313520
РИНЦ:	27135173
Chemical Abstracts:	2016:882866
Chemical Abstracts (print):	165:214159
OpenAlex:	W2414826031
Sciact:	19790

БД	Цитирований
Scopus	30
OpenAlex	33