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231223s2005 xx ||||| 00| ||eng c |
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|a pubmed24n0527.xml
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|a (DE-627)NLM158181026
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|a (NLM)16207038
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|a DE-627
|b ger
|c DE-627
|e rakwb
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|a eng
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|a Brutchey, Richard L
|e verfasserin
|4 aut
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|a Influence of surface modification of Ti-SBA15 catalysts on the epoxidation mechanism for cyclohexene with aqueous hydrogen peroxide
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|c 2005
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|a Text
|b txt
|2 rdacontent
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|a ohne Hilfsmittel zu benutzen
|b n
|2 rdamedia
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|a Band
|b nc
|2 rdacarrier
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|a Date Completed 10.04.2007
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|a Date Revised 06.10.2005
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|a published: Print
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|a Citation Status PubMed-not-MEDLINE
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|a The thermolytic molecular precursor method was used to introduce site-isolated Ti(IV) centers onto the surface of a mesoporous SBA15 support. The resulting surface Si-OH/Ti-OH sites of the Ti-SBA15 catalysts were modified with a series of (N,N-dimethylamino)trialkylsilanes, Me(2)N-SiMe(2)(R) (where R = Me, (n)Bu, or (n)Oc). Compared with the unmodified catalysts, the surface-modified catalysts are more active in the oxidation of cyclohexene with H(2)O(2) and exhibit a significantly higher selectivity (up to 58%) for cyclohexene oxide formation (vs allylic oxidation products). In situ Fourier transform infrared (FTIR) and diffuse reflectance UV visible (DRUV-vis) spectroscopies were used to probe this phenomenon, and it was determined that active sites with capped titanol centers, (SiO(surface))(3)Ti(OSiR(3)), likely undergo Ti-OOH formation upon addition of H(2)O(2) in a manner analogous to that for active sites of the type (SiO(surface))(3)TiOH. On the basis of the observation of similar Ti-OOH intermediates for both species, the electron-withdrawing effects on the Ti(IV) active site, resulting from the surface modification, are likely responsible for the observed increase in selectivity
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|a Journal Article
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|a Ruddy, Daniel A
|e verfasserin
|4 aut
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|a Andersen, Lars K
|e verfasserin
|4 aut
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|a Tilley, T Don
|e verfasserin
|4 aut
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| 773 |
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|i Enthalten in
|t Langmuir : the ACS journal of surfaces and colloids
|d 1992
|g 21(2005), 21 vom: 11. Okt., Seite 9576-83
|w (DE-627)NLM098181009
|x 1520-5827
|7 nnns
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| 773 |
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|g volume:21
|g year:2005
|g number:21
|g day:11
|g month:10
|g pages:9576-83
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|a GBV_ILN_721
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|a AR
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|d 21
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|h 9576-83
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