Indexed by:Journal Article

Date of Publication:2012-04-26

Journal:JOURNAL OF PHYSICAL CHEMISTRY C

Included Journals:Scopus、EI、SCIE

Volume:116

Issue:16

Page Number:9122-9131

ISSN:1932-7447

Abstract:The reaction intermediates for propylene epoxidation were investigated by in situ UV Raman spectroscopy. A feature at 837 cm(-1), which has been assigned to the O-O stretching mode in the Ti-OOH (eta(2)) species, was observed in Raman study for the first time. The physisorbed H2O2 and triangular Ti(O-2) species are also present at different stages during the in situ measurement. The results obtained by gas chromatography-Raman spectrometry (GC-Raman) during the propylene epoxidation process give direct evidence that the 6-coordinated Ti-OOH (eta(2)) intermediates are important active sites for propylene epoxidation. After adding CH3OH to the TS-1/H2O2/H2O/system, the Raman spectra show the existence of a Ti-O-CH3 moiety and 6-coordinated Ti-OOH (eta(2)) species. The five-numbered ring titanium hydroperoxo intermediate was not detected in this study. The results showed that the 6-coordinated Ti-OOH (eta(2)) species are active sites in the methanol-included epoxidation reaction process.