214
L. Wang et al. / Journal of Catalysis 246 (2007) 205–214
lectivity both as high as 99%. One of the main heavy species,
-chloro-1,2-propanediol, has a negative effect on the reuse of
3
TS-1 and Ti-MWW. A secondary synthesis of piperidine treat-
ment causes a structural rearrangement by partially removing
the silanol defect sites, which enhances framework hydropho-
bicity and improves the stability and lifetime of Ti-MWW. This
study indicates that Ti-MWW is a promising catalyst for the
selective synthesis of ECH.
Acknowledgments
Financial support was provided by the Science and Tech-
nology Commission of Shanghai Municipality (05DZ22306),
Program for New Century Excellent Talents in University
(NCET-04-0423), Pujiang Program of Shanghai Municipal-
ity (05PJ14041), 973 Program (2006CB202508), and Na-
tional Natural Science Foundation of China (20473027 and
Fig. 13. IR spectra in region of hydroxyl stretching vibration of Ti-MWW be-
fore (a) and after PI treatment (b). The spectra were taken after evacuating the
self-supported disk (30 mg in 20 mm diameter) at 773 K for 2 h. The spec-
tra were normalized to the same intensity of 1880-cm band due to the Si–O
overtone of zeolite framework [27].
−
1
2
0673038).
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−1
3
745 cm , due to the external or terminal silanols on the crys-
[
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[
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2
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ALC to ECH with H2O2. Ti-MWW favors MeCN or acetone
as a suitable solvent, whereas TS-1 prefers MeOH. The dif-
ferent solvent effects result in different behaviors in epoxide
solvolysis. Ti-MWW is capable of giving conversion and se-
[
[
[