Diffuse Reflectance Laser Flash Photolysis Study of Titanium-Containing Zeolites

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• 作者：Pedro Atienzar ; Avelino Corma ; Hermenegildo Garcí ; a ; and J. C. Scaiano
• 刊名：Chemistry of Materials
• 出版年：2004
• 出版时间：March 23, 2004
• 年：2004
• 卷：16
• 期：6
• 页码：982 - 987
• 全文大小：172K
• 年卷期：v.16,no.6(March 23, 2004)
• ISSN：1520-5002

文摘

A series of porous titanosilicates (Ti-preferrierite, Ti-ferrierite, Ti/ITQ-6, Ti/ITQ-2, andsilylated Ti/MCM-41), all of them active as alkene epoxidation catalysts, have been submittedto diffuse reflectance laser flash photolysis. The transient spectra in the microsecond timedomain exhibit characteristic absorption bands at 350 nm (sharp) and 450-800 nm(featureless) attributable to triplet ligand-to-metal charge-transfer state and ejected electrons,respectively. It is proposed that the relative intensity of these two bands is a reflection ofthe presence of isolated, tetrahedral Ti atoms versus Ti aggregates, the former beingconsidered the most active titanium sites in olefin epoxidation. Our study shows theapplicability of laser flash photolysis to the characterization of titanium atoms in titanosilicates.