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FTIR spectroscopic study of titanium-containing mesoporous silicate materials
Natalia N Trukhan1, Alexander A Panchenko, Emil Roduner
1Institute of Physical Chemistry, Stuttgart University, Germany. n.trukhan@ipc.uni-stuttgart.de
Langmuir : the ACS Journal of Surfaces and Colloids
|November 3, 2005
Summary
This study reveals that titanium-silicate materials exhibit Brønsted acidity, with TiO(2)-SiO(2) xerogels showing the highest acidity. Surface analysis identified unique titanium sites, correlating with catalytic activity in oxidation reactions.
Area of Science:
- Materials Science
- Catalysis
- Surface Chemistry
Background:
- Mesoporous titanium-silicates are advanced materials with potential catalytic applications.
- Understanding their surface acidity is crucial for optimizing their performance.
- Previous studies suggest a link between titanium content and catalytic activity.
Purpose of the Study:
- To investigate and compare the surface acidity of various mesoporous titanium-silicates.
- To identify specific acidic sites using spectroscopic techniques.
- To correlate surface acidity and titanium accessibility with catalytic activity.
Main Methods:
- Fourier Transform Infrared (FTIR) spectroscopy was employed.
- Adsorption of carbon monoxide (CO) at 80 K and acetonitrile-deuterated (CD(3)CN) at 293 K was performed.
- Spectroscopic results were compared with computational data from cluster models.
Main Results:
- Mesoporous titanium-silicates showed Brønsted acidity, with TiO(2)-SiO(2) xerogels exhibiting the highest acidity.
- FTIR analysis identified two distinct new adsorption sites on titanium-silicates compared to pure silicates.
- Titanium accessibility followed the order: TiO(2)-SiO(2) aerogel ≈ TiO(2)-SiO(2) xerogel > Ti-MMM ≈ Ti-MMM-2 > Ti-SBA-15.
Conclusions:
- The study elucidates the surface acidity characteristics of diverse mesoporous titanium-silicates.
- Specific titanium sites and their accessibility are identified, influencing catalytic behavior.
- The findings provide insights into the structure-activity relationship for titanium-silicate catalysts.