Synthesis and Characterization of Tin, Tin-Aluminum, and Tin-Boron Containing MFI Zeolites
Zeolites are an
intellectually fascinating and
technologically important class of materials used
chemical conversion and separation of small molecules. Their ability to
achieve these unit operations is a
result of the crystalline microporous structures enabling highly size-selective separations. Coupling
that with the ability to impart acidity to the zeolites through the introduction of trivalent elements such as aluminum and boron into the framework has led to zeolites finding a wide range of applications in the chemical and
petrochemical industry. Over the last 20-30
years beyond aluminum and boron,
shown that other elements including titanium, tin and germanium can
be introduced into the zeolite
lattice with varying
levels of success. This expansion of the zeolite framework composition space has led
to new uses for zeolites
a range of catalytic chemistries.
The synthesis and characterization of tin, tin/aluminum, and tin/boron containing MFI zeolites will be presented. It is shown that tin uptake is high (near 100%) and decreases with
the introduction of a second
heteroatom. Also, the boron uptake was found to be low for tin-boron-MFI samples, consistent with our
prior work on germanium-boron-MFI. XRD and
FE-SEM show that higher tin contents and higher aluminum and boron contents in the synthesis gel lead to smaller and less faceted crystals. Diffuse reflectance UV-Vis spectroscopy confirms the tetrahedral framework coordination of tin within the zeolite
no polymeric SnO2 can be detected, given the absence of a strong signal at 280
with UV-Vis, indicates the absence of an additional phase in the surface of these particles. In-Situ IR
spectroscopy, using methanol as a probe molecule, shows that the nature of number of acid
these materials changes in going from pure tin-MFI (very weakly acidic) to tin-aluminum-MFI (mildly acidic).
Lewis acid nature of the tin
was confirmed using
of d-acetonitrile treated samples.
Keywords: Tin-MFI, synthesis, probe molecule binding, mixed heteroatom zeolites
Barrer, Hydrothermal Chemistry of Zeolites, Academic Press Inc., London, 1982.
G.T. Kokotailo, S.L. Lawton, D.H. Olson,
Meier, Structure of Synthetic Zeolite ZSM- 5,
M. Taramasso, U.S.,
(4) A. Corma, L.T. Nemeth, M. Renz, S. Valencia, Sn-zeolite beta as a heterogeneous chemoselective catalyst for Baeyer-Villiger oxidations, Nature, 412 (2001) 423-425.
(5) Z. Gabelica, J.L. Guth, A Silicogermanate with a Si/Ge Ratio Greater Than or Equal to
2. Ann MFI Zeolite of Novel Composition,
Angewandte Chemie-International Edition in English,
28 (1989) 81-83.
Nataly Garcia, Scott Stevenson,
and Daniel F. Shantz. "Simultaneous isomorphous incorporation of boron
and germanium in
MFI zeolites." Microporous and
Mesoporous Materials 170 (2013): 131-140.
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