CHBE Seminar Series: Dongxia Liu
Tuesday, April 5, 2011
11:00 a.m.-12:15 p.m.
Room 2110 Chemical and Nuclear Engineering Bldg.
Professor Srinivasa Raghavan
Synthesis, Characterization, and Catalytic Behavior of MWW and MFI Zeolites with Dual Meso- and Micro-porosity
Department of Chemical Engineering and Materials Science
University of Minnesota
The meso/micro-zeolites couple the catalytic features of micropores and the improved access and transport consequence of mesopores in a single material, possessing the capacity of processing large molecules. The synthesis and catalytic behavior investigation of meso/micro-zeolites have become the subject of intense research. This talk highlights the synthesis, textural property characterization, and catalytic behavior of three emerging acidic meso-/micro-porous zeolite materials (pillared MWW, pillared MFI, and 3DOm MFI), with a focus on their catalytic behavior investigations using ethanol dehydration, monomolecular conversion of propane and isobutane, and alkylation of mesitylene with benzyl alcohol as probe reactions. The rate and apparent activation energy of the catalytic ethanol and small alkane probe reactions in zeolites possessing dual micro- and meso-porosity was comparable to conventional microporous MCM-22 (MWW) and MFI materials, implying that the catalytic behavior of Brønsted acid sites in materials with dual meso-/micro-porosity is preferentially dominated by the microporous environment possibly because it provides a better fit for adsorption of small alkane or alcohol reactant molecules. The apparent rate constant of the catalytic alkylation of mesitylene with benzyl alcohol in meso/micro-porous zeolites was higher than that of their microporous analogues, revealing the role of the mesoporosity in space-demanding catalytic reactions. Specifically, pillared MFI showed high reactivity and selectivity to etherification of benzyl alcohol in alkylation reactions of mesitylene with benzyl alcohol, indicating that it is an ideal catalyst for the etherification of 5-hydroxymethyl-2-furfural into 5,5 '(oxy-bis(methylene))bis-2-furfural, i.e., converting biomass into biofuels and chemicals.