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Hierarchical FAU- and LTA-Type Zeolites by Post-Synthetic Design: A New Generation of Highly Efficient Base Catalysts.
- Source :
-
Advanced Functional Materials . Sep2013, Vol. 23 Issue 15, p1923-1934. 12p. - Publication Year :
- 2013
-
Abstract
- Hierarchical FAU- and LTA-type catalysts are prepared by post-synthetic modifications and evaluated in the base-catalyzed Knoevenagel condensation of benzaldehyde with malononitrile. A novel route to attain mesoporous Al-rich zeolites (A and X) is demonstrated, while mesoporous Y and USY zeolites are prepared using recently developed methods. Base functionality is introduced by alkali ion exchange (Cs, Na) or by high-temperature nitridation in ammonia. A thorough characterization of the zeolites' structure, composition, porosity, morphology, and basicity demonstrates that the presence of a secondary mesopore network enhances the ion-exchange efficiency and the structural incorporation of nitrogen. The modified USY zeolites display twice the conversion, while the hierarchical A, X, and Y are up to 10 times more active based on the enhanced accessibility. These results demonstrate that the Knoevenagel condensation takes place predominately at the external surface, highlighting secondary porosity as a key criterion in the design of basic zeolite catalysts. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 1616301X
- Volume :
- 23
- Issue :
- 15
- Database :
- Academic Search Index
- Journal :
- Advanced Functional Materials
- Publication Type :
- Academic Journal
- Accession number :
- 86980999
- Full Text :
- https://doi.org/10.1002/adfm.201202320