Title of article :
Quantification of enhanced acid site accessibility in hierarchical zeolites – The accessibility index
Author/Authors :
Frederic Thibault-Starzyk، نويسنده , , Irina Stan، نويسنده , , S?nia Abell?، نويسنده , , Adriana Bonilla، نويسنده , , Karine Thomas، نويسنده , , Christian Fernandez and J. P. Amoureux، نويسنده , , Jean-Pierre Gilson، نويسنده , , Javier Pérez-Ram?rez، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2009
Pages :
4
From page :
11
To page :
14
Abstract :
An accessibility index (ACI) was derived from infrared spectroscopy of substituted alkylpyridines with different size (pyridine: 0.57 nm, 2,6-lutidine: 0.67 nm, and 2,4,6-collidine: 0.74 nm) 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.
Keywords :
Nitrobenzene , Aniline , nickel , Hydrogenation , Carbon dioxide , Pressure effect , intermolecular interaction
Journal title :
Journal of Catalysis
Serial Year :
2009
Journal title :
Journal of Catalysis
Record number :
1225690
Link To Document :
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