Methane Activation and Transformation on Ag/H-ZSM-5 Zeolite Studied with Solid-State NMR | Sciact - CRIS-system of Boreskov Institute of Catalysis

Methane Activation and Transformation on Ag/H-ZSM-5 Zeolite Studied with Solid-State NMR Full article

Journal

The Journal of Physical Chemistry C
ISSN: 1932-7447 , E-ISSN: 1932-7455

Output data

Year: 2013, Volume: 117, Number: 15, Pages: 7690-7702 Pages count : 13 DOI: 10.1021/jp4006795

Tags

Activation analysis; Aromatization; Benzene; Dehydrogenation; Dissociation; Ethane; Ethylene; Hydrides; Nuclear magnetic resonance spectroscopy; Oligomerization; Oligomers; Positive ions; Silver; Solid state physics

Authors

Gabrienko Anton A. ¹ , Arzumanov Sergei S. ¹ , Moroz Ilya B. ² , Toktarev Alexander V. ¹ , Wang Wei ³ , Stepanov Alexander G. ^1,2

Affiliations

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	State Key Laboratory of Applied Organic Chemistry and College of Chemistry and Chemical Engineering, Lanzhou University, 222 Tianshui South Road, Lanzhou, Gansu 730000, People’s Republic of China

Funding (1)

Russian Foundation for Basic Research

12-03-91162

With regard to a general interest in methane utilization in a rational way the activation and transformation of methane on Ag-modified zeolite ZSM-5 (Ag/H-ZSM-5) have been studied with solid-state NMR. The activation of methane occurs by dissociation of the C–H bond on silver cations via the “carbenium” pathway: methane C–H bond cleavage results in the methoxy groups (O–CH3) and possibly silver-hydride species (Ag–H). The formation of surface methoxy groups on Ag/H-ZSM-5 has been detected experimentally with 13C CP/MAS NMR at 508–623 K for the first time. A comparative analysis of the kinetics of the H/D exchange between methane and acid hydroxyl groups for H-ZSM-5 and Ag/H-ZSM-5 zeolites reveals a significant promoting effect of silver cations on the H/D exchange reaction and therefore on methane activation. This effect has been rationalized in terms of reversible methane dissociation on the surface of Ag/H-ZSM-5 zeolite and further involvement in the exchange of the methoxy groups and the silver-hydride species. Ethane represents the first intermediate product of methoxy group transformation. It is formed by the reaction of a methoxy group with methane. Further, dehydrogenation of ethane offers ethene, producing immediately π-complexes with Ag+ cations, which are stable at temperature as high as 673 K. At 823 K π-complexes decompose and ethene undergoes oligomerization, cyclization, dehydrogenation, and aromatization to give benzene. In the presence of methane, ethene π-complexes decompose and become involved in oligomerization and aromatization reaction at lower temperature, already at 673 K. Methane is also involved in the reaction of coaromatization with ethene. This involvement occurs by the alkylation of aromatics, formed from ethene, with methane. Further demethanation of methylbenzenes in the presence of dihydrogen evolved at the stages of ethene transformation to aromatics produces benzene as the main reaction product.

Gabrienko A.A. , Arzumanov S.S. , Moroz I.B. , Toktarev A.V. , Wang W. , Stepanov A.G.
Methane Activation and Transformation on Ag/H-ZSM-5 Zeolite Studied with Solid-State NMR
The Journal of Physical Chemistry C. 2013. V.117. N15. P.7690-7702. DOI: 10.1021/jp4006795 WOS Scopus РИНЦ ANCAN OpenAlex

Submitted:	Jan 21, 2013
Accepted:	Mar 19, 2013
Published online:	Apr 5, 2013
Published print:	Apr 18, 2013

Web of science:	WOS:000317950300033
Scopus:	2-s2.0-84876513055
Elibrary:	20437418
Chemical Abstracts:	2013:465050
Chemical Abstracts (print):	158:503556
OpenAlex:	W2317635331

DB	Citing
Web of science	67
Scopus	72
Elibrary	68
OpenAlex	79