(735a) Catalytic Conversion of Benzyl Alcohol Using Micro-/Mesoporous Zeolites

Authors: 
Liu, D., University of Maryland
Bhan, A., University of Minnesota
Tsapatsis, M., University of Minnesota
Hashimi, S. A., The Petroleum Institute


The meso-microporous zeolites couple the catalytic properties of micropores and the improved access and transport concequence of mesopores, capable of overcoming diffusional constraints in the diffusion limited reactions. This talk highlights the catalytic activity investigation on meso-microporous zeolite and three conventional microporous MFI zeolites using reactions of benzyl alcohol in aromatic solvents in a batch reactor. The reaction network was comprised of a parallel reaction, alkylation of aromatics with benzyl alcohol and self-etherification of benzyl alcohol, which occurred at different locations (external or internal surfaces) of the catalysts and were identified by using bulky aromatic solvent and selectively deactivating the external active sites using 2,6-diterbutyl pyridine (DTBP) titrant. Based on the alkylation reactions which occurred exclusively on external surface of the catalysts, we conclude that micro-mesoporous zeolites have similar external surface catalytic activity to that of microporous zeolites, and that micro-mesoporous zeolites enable efficient surface catalysis which is hard to achieve for the conventional microporous zeolites as their external surface area is many orders of magnitude less than the total catalyst surface area. By deactivating the external active sites with DTBP titant, the etherification reactions occurred exclusively in internal surface of the catalysts which allows us to examine the internal (microporous) catalytic activity.  The analysis on the internal reaction rates shows that the catalytic behavior follows the Thiele concept, from which the diffusion coefficient was evaluated. The overall (external and internal) etherification reactions were involved with an internal reaction, an external reaction and internal diffusion.
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