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| Author(s): |
Angela Albuquerque
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Química |
| Defense date: | 2006-07-14 |
| Examining board members: |
Heloise de Oliveira Pastore;
Paulo Gustavo Pries de Oliveira;
Dilson Cardoso;
Regina Buffon;
Inez Valéria Pagotto Yoshida
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| Advisor: | Heloise de Oliveira Pastore |
| Abstract | |
The synthesis of the vanadoaluminosilicate molecular sieve with MWW structure, [V,AI]-MCM-22, has been performed by static hydrothermal synthesis. As-synthesized, calcined, and H, Na or K ion-exchanged materiaIs were characterized by various analytical and spectroscopical techniques. It has also been prepared a material by ion-exchanging [AI]-MCM-22 with vanadyl ions, VO-[AI]-MCM-22. AlI the materiaIs presented a crystalIine structure similar to that observed for [AI]-MCM-22. The presence of redox sites (V/ V couples) was monitored by diffuse reflectance UV-vis spectroscopy and by Fourier transform infrared spectroscopy (FTlR) with CO adsorption at 100 K. Acid characteristics were monitored by FTlR with NH3 adsorption and by thermoprogrammed NH3 desorption (TPD). When tested in the oxidative dehydrogenation of propane catalytic reaction, vanadoaluminosilicates presented higher conversion values when compared to aluminosilicates, with similar selectivity data. Ion-exchange with alkaline ions may promote modulation in the acidity of the catalysts, making them more selective by decreasing their selectivity to products of cracking reactions. (AU) | |