Catalytic behavior of Brønsted acid sites in MWW and MFI zeolites with dual meso- and microporosity

Dongxia Liu, Aditya Bhan, Michael Tsapatsis, Saleh Al Hashimi

Research output: Contribution to journalArticlepeer-review

96 Scopus citations

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 languageEnglish (US)
Pages (from-to)7-17
Number of pages11
JournalACS Catalysis
Volume1
Issue number1
DOIs
StatePublished - Jan 7 2011

Keywords

  • Meso-/microporous zeolite
  • base titration
  • ethanol dehydration
  • hierarchical materials
  • isobutane activation
  • monomolecular alkane conversion
  • propane activation
  • shape selectivity

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