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Quantification of enhanced acid site accessibility in hierarchical zeolites – The accessibility index
- Source :
-
Journal of Catalysis . May2009, Vol. 264 Issue 1, p11-14. 4p. - Publication Year :
- 2009
-
Abstract
- An accessibility index (ACI) was derived from infrared spectroscopy of substituted alkylpyridines with different size (pyridine: 0.57nm, 2,6-lutidine: 0.67nm, and 2,4,6-collidine: 0.74nm) over hierarchical porous ZSM-5 crystals. The samples were prepared by selective silicon extraction of a commercial sample in NaOH (desilication), and they contained different degrees of intracrystalline mesoporosity. Our results demonstrate the enhanced accessibility of Brønsted acid sites in the hierarchical zeolites. For example, a relatively bulky molecule such as collidine, which probes practically no acid site of the parent medium-pore MFI structure, can access up to 40% of the acid sites in the mesoporous sample. The ACI is a powerful tool to standardize acid site accessibility in zeolites, and can be used to rank the effectiveness of synthetic strategies to prepare hierarchical zeolites. [Copyright &y& Elsevier]
Details
- Language :
- English
- ISSN :
- 00219517
- Volume :
- 264
- Issue :
- 1
- Database :
- Academic Search Index
- Journal :
- Journal of Catalysis
- Publication Type :
- Academic Journal
- Accession number :
- 39359934
- Full Text :
- https://doi.org/10.1016/j.jcat.2009.03.006