Abstract
The catalytic behavior of Brønsted acid sites in three acidic zeolite materials (one MWW and two MFI zeolites) containing dual meso-/microporosity was studied using ethanol dehydration and monomolecular conversion of propane and isobutane as probe reactions. The meso-/microporous MWW zeolite, MCM-36 or pillared MWW, consists of a zeolitic layer structure, with independent microporosity and mesoporosity within the layers and between the layers, respectively. A meso-/microporous MFI (pillared MFI) zeolite also contains a zeolitic layer structure, but with interconnected micropore and mesopore systems. A different meso-/microporous MFI zeolite, three-dimensionally ordered mesoporous-imprinted (3DOm-i) MFI, contains nanometer-sized spherical elements forming an opaline structure, with highly interconnected meso- and micropores. The rate and apparent activation energy of the catalytic probe reactions in zeolites possessing dual meso- and microporosity was comparable to conventional microporous MCM-22 (MWW) and MFI materials. This similarity in kinetic behavior between materials possessing dual meso-/microporosity and their microporous analogues when assessed under conditions of strict kinetic control implies that the catalytic behavior of Brønsted acid sites in materials with dual meso-/microporosity is preferentially dominated by the microporous environment possibly because it provides a better fit for adsorption of small alkane or alcohol reactant molecules.
Original language | English (US) |
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Pages (from-to) | 7-17 |
Number of pages | 11 |
Journal | ACS Catalysis |
Volume | 1 |
Issue number | 1 |
DOIs | |
State | Published - Jan 7 2011 |
Keywords
- Meso-/microporous zeolite
- base titration
- ethanol dehydration
- hierarchical materials
- isobutane activation
- monomolecular alkane conversion
- propane activation
- shape selectivity