Methane Mobility in Ag/H-ZSM-5 Zeolite in the Presence of Ethene: A View Based on PFG 1H MAS NMR Analysis of Methane Diffusivity
Methane Mobility in Ag/H-ZSM-5 Zeolite in the Presence of Ethene: A View Based on PFG 1H MAS NMR Analysis of Methane Diffusivity
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乙烯存在下 Ag/H-ZSM-5 沸石中的甲烷迁移率：基于 PFG 1H MAS NMR 甲烷扩散率分析的观点
DOI：
10.1021/acs.jpcc.5b05953
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发表时间：
2015
影响因子：
3.7
通讯作者：
A.G. Stepanov
中科院分区：
文献类型：
--
作者：
S.S. Arzumanov;D.I. Kolokolov;D. Freude;A.G. Stepanov
为了研究甲烷对乙烯在Ag/H-ZSM-5分子筛上反应活性的影响，用PFG ~ 1H MAS NMR谱研究了乙烯共吸附在Ag/H-ZSM-5分子筛上时甲烷的扩散系数。结果表明，在无乙烯存在下，甲烷的扩散比有乙烯共吸附时的扩散慢（活化能Ea = 29 kJ mol ~（-1））.在没有乙烯的情况下，甲烷扩散的较高的Ea值与位于沸石通道系统中的Ag+阳离子与甲烷的一些强相互作用有关。乙烯的存在加速了银离子的扩散，降低了扩散活化能，这是由于乙烯对Ag+形成π-络合物的屏蔽作用。甲烷与Ag+阳离子的直接相互作用的情况下被假定为提供显着降低的活化能和甲烷扩散的加速。两个合奏的甲烷分子不同的扩散率已被假定存在于沸石中的共吸附乙烯的存在下。两个合奏的扩散甲烷在沸石中的存在是合理的，在存在两个途径的甲烷扩散通过沸石通道系统。通过一种途径，甲烷可能扩散通过乙烯与Ag+阳离子和沸石酸OH基团的π-络合物。另一种途径可以包括甲烷在沸石通道中仅在沸石OH基团上扩散。
With regard to the influence of methane on the reactivity of ethene on Ag/H-ZSM-5 zeolite, the diffusivities of methane in the presence of ethene coadsorbed on Ag/H-ZSM-5 has been analyzed by PFG1H MAS NMR spectroscopy. It is established that the diffusion of methane in the absence of ethene occurs more slowly (activation energyEa= 29 kJ mol–1) than the diffusion of methane in the presence of coadsorbed ethene (Ea= 6–8 kJ mol–1). The higher value ofEafor the methane diffusion in the absence of ethene was related with some strong interaction of methane with Ag+cations located in the zeolite channel system. Acceleration of diffusion and a decrease of its activation energy in the presence of ethene were assigned to the shielding effect of ethene adsorbed on Ag+cations to form π-complexes. An absence of direct interaction of methane with Ag+cations was assumed to provide a significant decrease of activation energy and acceleration of methane diffusion. Two ensembles of methane molecules different by diffusivity have been assumed to exist in the zeolite in the presence of coadsorbed ethene. The presence of two ensembles of diffusing methane in the zeolite was rationalized in terms of the existence of two pathways of methane diffusion through the zeolite channel system. By one pathway, methane presumably diffuses over π-complexes of ethene with Ag+cations and the zeolite acid OH groups. The other pathway may include the methane diffusion in the zeolite channels exclusively over the zeolite OH groups.
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影响因子：
7.4
作者：
FERGUSON, DB;HAW, JF
通讯作者：
HAW, JF
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DOI：
10.1039/ft9918701935
发表时间：
1991
期刊：
Journal of the Chemical Society, Faraday Transactions
影响因子：
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作者：
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通讯作者：
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影响因子：
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作者：
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影响因子：
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作者：
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通讯作者：
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DOI：
--
发表时间：
2002
期刊：
影响因子：
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作者：
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通讯作者：
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