DICP OpenIR
Study on the external surface acidity of MCM-22 zeolite: Theoretical calculation and P-31 MAS NMR
Wang, Y; Zhuang, JQ; Yang, G; Zhou, DH; Ma, D; Han, XW; Bao, XH
刊名JOURNAL OF PHYSICAL CHEMISTRY B
2004-01-29
DOI10.1021/jp034989y
108期:4页:1386-1391
收录类别SCI
文章类型Article
WOS标题词Science & Technology ; Physical Sciences
类目[WOS]Chemistry, Physical
研究领域[WOS]Chemistry
关键词[WOS]SOLID-STATE NMR ; CATALYTIC-ACTIVITY ; H-MCM-22 ZEOLITES ; AB-INITIO ; ADSORPTION ; BETA ; TRIMETHYLPHOSPHINE ; DIFFUSION ; CHEMISTRY ; CRACKING
英文摘要The acidity on the external surface of the MCM-22 zeolite was studied by theoretical calculations combined with a magic angle spinning (MAS) NMR experiment. The IT MAS NMR spectrum of triphenylphosphine (PPh3) adsorbed on the MCM-22 zeolite and the XRF (X-ray fluorescence) element analysis showed that there were about 6% Bronsted acidic sites distributed on the external surface. During theoretical calculations, PPh3 was used as the probe molecule to further study the nature of interaction. Periodic molecular mechanical simulations revealed that the probe molecule preferred to adsorb on the 12 MR external surface pockets of the MCM-22 zeolite and was too large to enter completely into the surface pockets. It preferred to locate at the openings of external surface pockets, with one alkyl inserting into the pockets of the supercage, whereas the others remained in the outside, which confirmed the result that only 6% Bronsted acid sites were detectable by IT MAS NMR using PPh3 as the probe molecule. Moreover, periodic MM calculation indicated that PPh3 was able to adsorb on T1 and T4 sites, which were the most possible sites for the A1 introduced into the zeolite lattice. The existence of two Bronsted-bound PPh3 peaks at 11.1 and 14.8 ppm in the P-31 MAS NMR spectrum was strongly supported by the above theoretical results. Thus, the molecular mechanical simulation not only provided structural support to the interpretation of NMR experiment but also perfectly agreed with the results from P-31 MAS NMR measurements. The structures and interaction energies of the acid-base complexes were further calculated by DFT method. The quantum mechanical calculations indicated that the protonic H atoms of the MCM-22 zeolite were transferred to the probe molecules, resulting in the "ionic" structure, which was in good agreement with the result of Lunsford etc. Because the Bronsted acidity was associated with the ability of transferring proton, the calculation results can give a qualitative understanding of the acidic strength at the openings of the external surface pockets of the MCM-22 zeolite. The effects of the cluster model and the functional level were also discussed in detail.
语种英语
WOS记录号WOS:000188535700030
引用统计
被引频次:26[WOS]   [WOS记录]     [WOS相关记录]
文献类型期刊论文
条目标识符http://cas-ir.dicp.ac.cn/handle/321008/139344
专题中国科学院大连化学物理研究所
作者单位Chinese Acad Sci, Dalian Inst Chem Phys, State Key Lab Catalysis, Dalian 116023, Liaoning, Peoples R China
推荐引用方式
GB/T 7714
Wang, Y,Zhuang, JQ,Yang, G,et al. Study on the external surface acidity of MCM-22 zeolite: Theoretical calculation and P-31 MAS NMR[J]. JOURNAL OF PHYSICAL CHEMISTRY B,2004,108(4):1386-1391.
APA Wang, Y.,Zhuang, JQ.,Yang, G.,Zhou, DH.,Ma, D.,...&Bao, XH.(2004).Study on the external surface acidity of MCM-22 zeolite: Theoretical calculation and P-31 MAS NMR.JOURNAL OF PHYSICAL CHEMISTRY B,108(4),1386-1391.
MLA Wang, Y,et al."Study on the external surface acidity of MCM-22 zeolite: Theoretical calculation and P-31 MAS NMR".JOURNAL OF PHYSICAL CHEMISTRY B 108.4(2004):1386-1391.
条目包含的文件
条目无相关文件。
个性服务
推荐该条目
保存到收藏夹
查看访问统计
导出为Endnote文件
谷歌学术
谷歌学术中相似的文章
[Wang, Y]的文章
[Zhuang, JQ]的文章
[Yang, G]的文章
百度学术
百度学术中相似的文章
[Wang, Y]的文章
[Zhuang, JQ]的文章
[Yang, G]的文章
必应学术
必应学术中相似的文章
[Wang, Y]的文章
[Zhuang, JQ]的文章
[Yang, G]的文章
相关权益政策
暂无数据
收藏/分享
所有评论 (0)
暂无评论
 

除非特别说明,本系统中所有内容都受版权保护,并保留所有权利。