Catalysis Letters

, Volume 141, Issue 8, pp 1057–1066

Mechanistic and Adsorption Studies of Relevance to Photocatalysts on Titanium Grafted Mesoporous Silicalites

Article

DOI: 10.1007/s10562-011-0644-9

Cite this article as:
Danon, A., Stair, P.C. & Weitz, E. Catal Lett (2011) 141: 1057. doi:10.1007/s10562-011-0644-9

Abstract

Ti-SBA-15 and Ti-MCM-41 were synthesized and evaluated as possible photocatalysts for the reduction of CO2, and for the photo-Kolbe decomposition of acetic acid. UV-Raman was used to study the adsorption of carbon dioxide, water, formic acid, and acetic acid over Ti-MCM-41 by monitoring the UV enhanced resonance peak of the totally symmetric stretching band of the grafted Ti species at 1,085 cm−1. Acetic and formic acid dissociate on Ti-SBA-15 and Ti-MCM-41 to form acetate and formate, respectively. The conjugate bases subsequently interact strongly with Ti sites. Water interacts with the Ti sites, while no change in the amplitude of the 1,085 cm−1 band is observed in the presence of CO2. Photocatalysis experiments indicate that these mesoporous silicalites are active in the photo-Kolbe decomposition of acetic acid. CO2 is formed by reaction of a hole with the acetate carboxylate groups. The methyl radical co-products react with a surface proton and an electron to form methane. No products resulting from the dimerization of methyl radicals are observed, presumably because of the highly dispersed active sites.

Graphical Abstract

Keywords

Photocatalysis Photo-decomposition Mesoporous silicalites Titanium grafted Ti-SBA-15 Ti-MCM-41 

Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  1. 1.Institute for Catalysis in Energy Processes and Department of ChemistryNorthwestern UniversityEvanstonUSA

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