1H and 13C MAS NMR studies of light alkanes activation over MFI zeolite modified by Zn vapour
1H and 13C MAS NMR studies of light alkanes activation over MFI zeolite modified by Zn vapour
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DOI：
10.1016/j.ssnmr.2009.01.005
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发表时间：
2009-04-01
影响因子：
3.2
通讯作者：
Pirogov, Yuri A.
中科院分区：
文献类型：
--
作者：
Kolyagin, Yuriy G.;Ivanova, Irina I.;Pirogov, Yuri A.
采用原位H-1和C-13核磁共振技术研究了由锌蒸汽反应得到的全交换Zn2+/MFI催化剂上甲烷、乙烷和丙烷转化的早期阶段。原位技术揭示了烷烃与Zn2+阳离子的强相互作用，相应的核磁共振谱线明显移位。此外，在常温下还可检测到甲基锌、乙基锌和正丙基锌的形成以及桥接和硅醇表面的羟基。这些结果表明烷烃在催化剂的(ZO)- zn2 +-(OZ)和(ZO)- zn2 +-(OSi)活性位点上解离吸附。在甲烷起始反应物中，解离吸附是一个死端表面反应，而在乙烷和丙烷的情况下，解离吸附似乎是催化循环的开始，导致烯烃和二氢的形成以及含锌催化位点的再生。(C) 2009爱思唯尔公司版权所有。
The early stages of methane, ethane and propane conversion were studied by in situ H-1 and C-13 MAS NMR techniques over fully exchanged Zn2+/MFI catalyst obtained by the reaction with zinc vapour. The in situ techniques revealed strong interaction of alkanes with Zn2+ cations evidenced by significant shift of the corresponding NMR lines. Besides that, the formation of methyl zinc, ethyl zinc and n-propyl zinc species along with bridging and silanol surface OH-groups was detected already at the ambient temperature. These results pointed to dissociative adsorption of alkanes over (ZO)-Zn2+-(OZ) and (ZO)-Zn2+-(OSi) active sites of the catalyst. The dissociative adsorption was shown to be a dead-end surface reaction in the case of methane starting reactant, while in the case of ethane and propane, it appeared to be responsible for the initiation of the catalytic cycle leading to alkenes and dihydrogen formation and regeneration of zinc containing catalytic sites. (C) 2009 Elsevier Inc. All rights reserved.