Quantification of enhanced acid site accessibility in hierarchical zeolites – The accessibility index

Thibault-Starzyk, Frédéric; Stan, Irina; Abelló, Sònia; Bonilla, Adriana; Thomas, Karine; Fernandéz, Christian; Gilson, Jean‐Pierre; Pérez‐Ramírez, Javier

doi:10.1016/j.jcat.2009.03.006

Cited by 282 publications

(239 citation statements)

References 26 publications

Supporting

Mentioning

229

Contrasting

Unclassified

Order By: Relevance

“…Substituted pyridines have been widely used to study and quantify the enhanced accessibility of acid sites in hierarchical zeolites, given their impediment to diffuse through small micropores. [26,[45][46][47] . In particular, 2,4,6-trimethilpyridine (2,4,6-TMP) with a kinetic diameter ca.…”

Section: Resultsmentioning

confidence: 99%

Creating Accessible Active Sites in Hierarchical MFI Zeolites for Low‐Temperature Acid Catalysis

et al. 2016

View full text Add to dashboard Cite

A versatile desilication design strategy for the creation of hierarchical H-ZSM-5 catalysts with different Si/Al ratio has been demonstrated. The nature, strength and the accessibility of the acid sites after the alkaline treatment was elucidated by employing a range of physico-chemical characterization tools; notably probebased FTIR spectroscopy along with SS MAS-NMR. In addition, structural and textural properties of the hierarchical zeolites were also explored and compared to their corresponding microporous analogues. CO was used to probe the acidic properties of the hierarchical zeolites with the concomitant deployment of a bulky molecular probe, 2,4,6-trimethylpyridine (collidine), which is too large to access the micropores, to specifically investigate the enhanced accessibility of the active sites. The hierarchical zeolites were evaluated in the industrially relevant, acid-catalyzed Beckmann rearrangement of cyclohexanone oxime to -caprolactam, the precursor for Nylon-6, in liquid phase and at low-temperatures. The catalytic findings with the hierarchical catalysts reveal a significant enhancement in the production of -caprolactam, compared with the parent microporous H-ZSM-5 zeolite, thereby highlighting the merits of our design approach in facilitating enhanced diffusion and masstransfer.

show abstract

Section: Resultsmentioning

confidence: 99%

Creating Accessible Active Sites in Hierarchical MFI Zeolites for Low‐Temperature Acid Catalysis

et al. 2016

View full text Add to dashboard Cite

show abstract

“…The diameter of lutidine (6.7 Å) is larger than the 11 channel diameter of ZSM-5 zeolites. This molecule is often used for evaluation of the acid 12 sites located on the external surface and in the meso-and macropores of zeolites [64]. The 13 FTIR spectra of adsorbed lutidine are shown in Figure 7.…”

Section: Acidity Of the External Surface Of Zeolite Crystallitesmentioning

confidence: 99%

Direct dimethyl ether synthesis from syngas on copper–zeolite hybrid catalysts with a wide range of zeolite particle sizes

Cai

Palčić

Subramanian

et al. 2016

Journal of Catalysis

View full text Add to dashboard Cite

“…Usually, this behavior is assigned to improved mass transfer due to the introduction of a secondary mesoporous network of inter-or intra-crystalline nature. Indeed, hierarchically porous zeolites offer enhanced accessibility and transport of molecules to and from the active sites [5][6][7][8], therefore enhancing catalyst effectiveness [1][2][3][4]9]. It is of utmost importance to be able to characterise and to guarantee good pore connectivity in order to take benefits from those advantages [10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Mesoporous ZSM-5 Zeolites in Acid Catalysis: Top-Down vs. Bottom-Up Approach

et al. 2017

View full text Add to dashboard Cite

Abstract:A top-down desilication of Al-rich ZSM-5 zeolites and a bottom-up mesopores creating method were evaluated in this study. Three liquid-solid and one gas-solid heterogeneously-catalysed reactions were chosen to establish relationships between zeolites textural properties and their catalytic behavior in acid-catalysed model reactions that are influenced by shape selectivity: Diels-Alder cyclization between isoprene and methylacrylate, Methanol-to-Olefins (MTO) reaction, chlorination of iodobenzene with trichloroisocyanuric acid (TCCA), and Friedel-Crafts acylation of anisole by carboxylic acids with differing sizes. It is found amongst others that no optimal mesoporosity for all the different reactions can be easily obtained, but depending on the chosen application, a specific treatment has to be set to achieve high activity/selectivity and stability.

show abstract

Quantification of enhanced acid site accessibility in hierarchical zeolites – The accessibility index

Cited by 282 publications

References 26 publications

Creating Accessible Active Sites in Hierarchical MFI Zeolites for Low‐Temperature Acid Catalysis

Creating Accessible Active Sites in Hierarchical MFI Zeolites for Low‐Temperature Acid Catalysis

Direct dimethyl ether synthesis from syngas on copper–zeolite hybrid catalysts with a wide range of zeolite particle sizes

Mesoporous ZSM-5 Zeolites in Acid Catalysis: Top-Down vs. Bottom-Up Approach

Contact Info

Product

Resources

About