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Surface properties of MCM-41 containing aluminium and titanium
|Diana C. Azevedo 1, Rinaldo S. Araújo 3, Débora S. Maia 1, Célio L. Cavalcante Jr 1, Enrique Rodriguez Castellon 2, Antonio Jimenez-Lopez 2|
1. Universidade Federal do Ceará (UFC), Campus do Pici, bl. 709, Fortaleza 60455760, Brazil
The surface acidity of mesoporous molecular sieves of aluminium and titanium was evaluated using four different techniques: n-butylamine volumetry, cyclohexylamine thermodesorption, temperature programmed desorption of ammonia and adsorption of pyridine. The nature, strength and concentration of the acid sites were determined and correlated to the results of a probe reaction of anthracene oxidation to 9,10-anthraquinone (in liquid phase). In general, the surface acidity was highly influenced by the nature, location and coordination of the metal species (Al and Ti) in the mesoporous samples. Moderate to strong Brönsted acid sites were identified for the Al-MCM-41 sample in a large temperature range. For mesoporous materials containing Ti, the acidity was represented by a combination of weak to moderate Brönsted and Lewis acid sites. Higher acidity of moderate strength, found in the Ti-HMS sample, enhanced both conversion and selectivity in the oxidation reaction of anthracene, producing higher yields of 9,10-anthraquinone.
Presentation: Poster at E-MRS Fall Meeting 2008, Symposium D, by Diana C. Azevedo
See On-line Journal of E-MRS Fall Meeting 2008
Submitted: 2008-05-12 17:01 Revised: 2009-06-07 00:48