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The Properties of Methylene-and Amine-Substituted Zeolites from First Principles

Summary: The Properties of Methylene- and Amine-Substituted Zeolites
from First Principles
Roope Astala and Scott M. Auerbach*
Contribution from the Department of Chemistry and Department of Chemical Engineering,
UniVersity of Massachusetts, Amherst, Massachusetts 01003
Received August 12, 2003; E-mail: auerbach@chem.umass.edu
Abstract: All-silica zeolite frameworks doped with methylene and amine groups are studied using density
functional theory-based electron structure calculations. Strain energies are calculated in a novel way, by
comparing zeolite energies with appropriate polymer reference systems. The modified zeolites are found
to be mechanically stable structures with surprisingly little strain. Distortions due to impurities result in
broadened Si-O-Si angle distributions in the lattice surrounding defects. Our results suggest that zeolites
can accommodate both methylene and amine groups at high concentrations with minimal strain. The amine-
doped zeolites are strong Lewis bases suggesting novel applications in base catalysis.
1. Introduction
Zeolites are nanoporous crystalline silicates with a wide
variety of important properties and applications.1 Recent efforts
to broaden the scope of zeolite compositions have yielded LTA
and MFI frameworks2 with bridging oxygen atoms replaced by
CH2 groups.3 Such materials may have interesting catalytic,
electronic, and structural properties, which remain to be inves-


Source: Auerbach, Scott M. - Department of Chemistry, University of Massachusetts at Amherst


Collections: Chemistry