| Summary: | 碩士 === 國立成功大學 === 化學工程學系 === 86 === In this study, the sol-gel technique and oil-drop method were
used to prepare the microporous alumina support. The influences
of sol-gel process variables, such as acid/alkoxide/water molar
ratio, on the microstructure of the support were investigated.
Furthermore, effects of the microstructure of γ-Al2O3
support on the properties of Pt/γ-Al2O3 catalyst were also
studied. From the experimental esults, the crush strength of
the Al2O3 support prepared by sol-gelprocess (~35N/mm) is much
higher than those commercial ones (~10N/mm). The microstructure
of the Al2O3 support was influenced by the preparation
variables,i.e. acid/alkoxide/water molar ratio. When the acid/
alkoxide ratio varied from 0.03 to 0.15, the specific surface
area of the support was in the range of 225 to 243 m2/g, the
pore size was from 51 to 56 *, and the pore volume was from
0.43 to 0.46 cm3/g. When the acid/koxide ratio varied from 1.0
to 1.5, the specific surface area of the support was in the
range of 235 to 253 m2/g, the pore size was from 52 to 55 *, and
the pore volume was from 0.46 to 0.48 cm3/g. When the alkoxide/
water ratio varied from 1/ 50 to 90, the specific surface area
of the support was in the range of 232 to 257 m2/g, the pore
size was from 49 to 55 *, and the pore volume was from 0.43 to
0.46 cm3/g.It showed that supports with different microstructure
can be obtained by controlling preparation variables of sol-gel
process.The Pt-catalyst prepared with H2PtCl6 as the precursor
is an egg-shell type. The Pt dispersion and the impregnating
depth were influenced by the acid/alkoxide/water molar ratio and
metal loading. The maximum depth of impregnation was obtained at
loading 2wt% Pt, and the maximum metal dispersion was at 1wt%
Pt.I the sol-gel process, with the acid/alkoxide ratio was from
0.07 to 0.15 in the sol-gel process, the profiles of Pt
concentration in the support particles showed a U-type. The Pt-
impregnating depth was increased with increasing the acid
amount, but the Pt-dispersion showed no significant change as
the acid amount was varied. Furthermore, it showed that maximum
Pt-dispersion can be obtained when the acid/alkoxide ratio was
0.07/1.2.
|
|---|
