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Kwak, Ja Hun
Molecular Catalysis lab
Research Interests
  • Heterogeneous catalysis, molecular catalysis, ASlumima, zeolites

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Characterizing Surface Acidic Sites in Mesoporous-Silica-Supported Tungsten Oxide Catalysts Using Solid-State NMR and Quantum Chemistry Calculations

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dc.contributor.author Hu, Jian Zhi ko
dc.contributor.author Kwak, Jahun ko
dc.contributor.author Wang, Yong ko
dc.contributor.author Hu, Mary Y. ko
dc.contributor.author Turcu, Romulus V. ko
dc.contributor.author Peden, Charles H. F. ko
dc.date.available 2015-07-23T02:10:53Z -
dc.date.created 2015-07-21 ko
dc.date.issued 2011-12 -
dc.identifier.citation JOURNAL OF PHYSICAL CHEMISTRY C, v.115, no.47, pp.23354 - 23362 ko
dc.identifier.issn 1932-7447 ko
dc.identifier.uri https://scholarworks.unist.ac.kr/handle/201301/12297 -
dc.identifier.uri http://pubs.acs.org/doi/abs/10.1021/jp203813f ko
dc.description.abstract The acidic sites in dispersed tungsten oxide supported on SBA-15 mesoporous silica were investigated using a combination of pyridine titration, both fast- and slow-MAS N-15 NMR, static H-2 NMR, and quantum chemistry calculations. It is found that the bridging acidic -OH groups in surface-adsorbed tungsten dimers or multimers (i.e., W-OH-W) are the Bronsted acid sites. The unusually strong acidity of these Bronsted acid sites is confirmed by quantum chemistry calculations. In contrast, terminal W-OH sites are very stable and only weakly acidic as are terminal Si-OH sites. Furthermore, molecular interactions between pyridine molecules and the Bronsted and terminal W-OH sites for dispersed tungsten oxide species are strong. This results in restricted molecular motion for the interacting pyridine molecules even at room temperature, that is, a reorientation mainly about the molecular C-2 symmetry axis. The restricted reorientation results in efficient H-1-N-15 cross-polarization, making it possible to estimate the relative ratio of the Bronsted to the weakly acidic terminal W-OH sites in the catalyst using the slow-MAS H-1-N-15 CP PASS method ko
dc.description.statementofresponsibility close -
dc.language ENG ko
dc.publisher AMER CHEMICAL SOC ko
dc.subject CHEMICAL-SHIFT-ANISOTROPY ko
dc.subject TENSOR PRINCIPAL VALUES ko
dc.subject ANGLE TURNING EXPERIMENT ko
dc.subject MAGIC-ANGLE ko
dc.subject N-15 NMR ko
dc.subject SKELETAL ISOMERIZATION ko
dc.subject SPINNING NMR ko
dc.subject ACTIVATED CARBON ko
dc.subject POWDER PATTERNS ko
dc.subject GAMMA-ALUMINA ko
dc.title Characterizing Surface Acidic Sites in Mesoporous-Silica-Supported Tungsten Oxide Catalysts Using Solid-State NMR and Quantum Chemistry Calculations ko
dc.title.alternative Characterizing Surface Acidic Sites in Mesoporous-Silica-Supported Tungsten Oxide Catalysts Using Solid-State NMR and Quantum Chemistry Calculations ko
dc.type ARTICLE ko
dc.identifier.scopusid 2-s2.0-82155170629 ko
dc.identifier.wosid 000297195200015 ko
dc.type.rims ART ko
dc.description.wostc 2 *
dc.description.scopustc 2 *
dc.date.tcdate 2015-12-28 *
dc.date.scptcdate 2015-11-04 *
dc.date.scptcdate 2015-11-04 *
dc.identifier.doi 10.1021/jp203813f ko
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