(475b) Characterizing Zeolite Surface Growth At the Microscopic Level Using in Situ Atomic Force Microscopy

Characterizing Zeolite Surface Growth at the Microscopic Level using In Situ Atomic Force Microscopy

Alexandra I. Lupulescu, Jeffrey D.
Rimer

University of Houston, Department
of Chemical and Biomolecular Engineering,

4800 Calhoun Rd., Houston, TX 77004

The exceptional thermal stability,
unique shape-selectivity, and high acidity of zeolites
contribute to their frequent use as industrial catalysts. The inability to a priori control single crystal growth,
however, often yields materials with limited catalytic performance due to long,
tortuous internal diffusion pathlengths, as well as restricted
access to surface active sites. Rational design approaches capable of
selectively tailoring zeolite morphology and structure can dramatically improve
catalyst activity and lifetime ^1,2, and given
the potential application of zeolite catalysts for alternative fuels production
and vehicle emission technologies, there exists a critical need to expand the fundamental
understanding of zeolite growth as well as design more
robust synthetic schemes to optimize zeolite
catalysts ³. We will discuss a new advancement in atomic force
microscopy (AFM) to image zeolite surface growth in situ, which allows zeolite catalysts to be characterized under realistic
synthesis conditions. AFM offers unparalleled insight into
the surface mechanism of zeolite growth at
near-molecular resolution ^4,5.
Here, we will present the first application of AFM to continuously image zeolite surface step growth at elevated temperatures and
long periods of time (i.e. greater
than 10 hours). We will discuss the distinctive set of challenges that zeolite in situ
growth presents and a comprehensive study of silicalite-1 growth under various conditions,
including the effect of zeolite growth modifiers
(ZGMs), which are molecular additives used to mediate anisotropic growth rates
of zeolites and tailor their bulk crystal habit ^6,7.

[1] Choi, M., Na, K., Kim, J., Sakamoto, Y., Terasaki O., Ryoo, R.,
Nature 461 (2009)
246-249

[2] Corma, A., J. Catalysis
216 (2003) 298-312

[3] Davis,
M.E., Lobo, R.F.. Chem.
Mater. 1992,
4, 756-768.

[4]
Anderson, M. Current Opinion in Solid State
and Material Science. 2001,
5, 407-415.

[5] John,
N.S., Stevens, S.M., Terasaki, O., Anderson, M.A. Chem. Eur. J. 2010,
16, 2220-2230.

[6] Rimer, J.D., An, Z., Zhu, Z., Lee,
M.H., Goldfarb, D.S., Wesson, J.A., Ward, M.D., Science

 330 (2010)
337-341

[7] Lupulescu, A.I. and Rimer,
J.D., Angew. Chem. Int. Ed. 51 (2012) 3345-3349