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Pore-Size Engineering of Silicon Imido Nitride
for Catalytic Applications**
David Farrusseng, Klaus Schlichte, Bernd Spliethoff,
Annette Wingen, Stefan Kaskel,* John S. Bradley, and
Ferdi Schüth
[
3] C. S. Chen, Y. Fujimoto, G. Girdaukas, C. J. Sih, J. Am. Chem. Soc.
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Microporous and mesoporous materials with high internal
surface area and pore volume play a key role in the
development of new heterogeneous catalysts and solid
membranes.[ The strategy in the synthesis of materials with
well defined pore structure is to direct the networking of
molecular or ionic precursors by a templating agent, which
can be a molecule, an ion, a polymer, or a supramolecular
assembly.[ Removal of the occluded template produces
materials with patterns of characteristic pore size, shape,
and structure. Although there is a growing interest in
expanding these templating routes to materials other than
oxides, only in the case of sulfides and some super-Prussian-
blue compounds have micro- and mesoporous inorganic
nonoxide materials been synthesized.[ Nitrido-sodalites with
very small pores, probably inaccessible to organic substrates,
1
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[
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were obtained from the solid-state reaction of HPN and
2
divalent metal salts.[
4]
3893.
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Several methods for the synthesis of dense silicon nitride
starting from elemental silicon, silicon chloride, or even
carbodiimide have been reported. However, the first micro-
[
[5]
porous silicon imido nitrides with a mean pore size of 0.7 nm
were synthesized by Bradley and Dismukes in pyrolysis
reactions of polysilazanes.[ Mesoporous silicon imido nitride
[
[
6]
60, 105 ± 111.
15] The assay also yields a linear increase in absorption when increasing
concentrations of sodium acetate are used; see also reference [12] and
the instructions for use enclosed with the commercial test-kit for
accuracy of the method.
with a narrow pore-size distribution (d 5.6 nm) and a high
av
2
� 1
specific surface area (up to 1000 m g ) was obtained recently
using the ammonolysis of silicon tetrachloride in organic
solvents.[
7]
[
[
16] E. M. Anderson, K. M. Larsson, O. Kirk, Biocatal. Biotransform.
1998, 16, 181 ± 204.
We describe herein a template-assisted method which
allows, for the first time, tailoring the pore size of microporous
silicon nitride materials in a wide range from primary to
secondary micropores. In this procedure, tris(dimethylami-
17] Eapp values are the ratio of initial rates determined from the hydrolysis
of pure R or S enantiomers. Etrue values are derived from resolutions of
racemates and therefore also include competition between the two
enantiomers for the active site of the enzyme.
18] More than 50000 mutants can be screened per day, if the analysis time
can be reduced to about 1 min per test and faster pipetting steps are
possible.
[
8]
[
no)silylamine [(CH ) N] SiNH 1
is ammonolyzed in a
concentrated solution of CH (CH ) NH (n 11 ± 17) in hot
3
2
3
2
3
2
n
2
acetonitrile. The ammonolysis can be considered as an
analogue of silicon oxide manufacture by sol ± gel methods
using prehydrolyzed tetramethoxysilane and water. After
cooling to room temperature, a gel forms which is dried and
heated slowly to 823 K in flowing ammonia. According to
nitrogen physisorption experiments (Figure 1), such materials
prepared using alkylamines of different chain length
[*] Dr. S. Kaskel, Dr. D. Farrusseng, K. Schlichte, B. Spliethoff,
Dr. A. Wingen, Dr. F. Schüth
Max-Planck-Institut für Kohlenforschung
Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr (Germany)
Fax : (49)208-306-2995
E-mail: kaskel@mpi-muelheim.mpg.de
Dr. J. S. Bradley
Department of Chemistry
University of Hull
Cottingham Road, Hull HU6 7RX (UK)
[
**] We thank Dr. P. gren and U. Specht for helpful discussions on
physisorption and precursor syntheses. A Reimar Lüst Fellowship for
S.K. was provided by the Max Planck Society.
4204
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1433-7851/01/4022-4204 $ 17.50+.50/0
Angew. Chem. Int. Ed. 2001, 40, No. 22