(618w) Effect of Dual Templates On Texture Properties of Mesoporous Alumina Prepared by Spray Pyrolysis

ABSTRACT

Porous alumina is one of
important engineering materials due to its catalytic, electronic, and
biomedical properties. Mostly, mesoporous alumina has been synthesized by a
liquid-phase reaction method using surfactant micelles or organic additives as
structure-directing agents. In most applications, the mesoporous alumina should
have a high surface area, well-defined pore structure, and a narrow pore size
distribution. So, many researchers have been devoted to synthesize high porous
alumina with regularity in pore size. Recently, an aerosol
route using spray-drying and self-assembly was reported as a potential method
to prepare mesoporous particles with high surface area. Most of researches
using the aerosol route are focusing on silica or metal/silica.

In
this work, a conventional spray pyrolysis process was applied to prepare
mesoporous alumina particles with spherical shape. In special, various dual
templates such as CTAB, CTAC, P123, CTAB/P123, and CTAC/P123 were used to
investigate the changes in the texture properties of alumina. Fig.1 shows
nitrogen-adsorption–desorption isotherms of alumina particles
prepared by the spray pyrolysis with the CTAB and CTAB/P123 mixture as a
template. The prepared alumina shows a typical type IV isotherm. The BET surface
area of the alumina
prepared by using only CTAB was 233 m²/g. Also, the sample prepared from
the dual template, CTAB/P123, had the BET surface area of 282
m²/g. In terms of pore size and pore volume, however, the
alumina particles prepared from the dual template (CTAB/P123) were larger than
the alumina prepared from using the only CTAB template. On the base of BJH
desorption isotherms, the pore size distribution was calculated and shown in
Fig. 1. When the only CTAB was used, a broad pore size distribution was
observed compared with that for the alumina sample prepared from the CTAB/P123
dual template. From this result, it was clear that using the dual template is
helpful to improve the pore properties of alumina particles when they are prepared
by the spray pyrolysis. The TEM images of the mesoporous alumina prepared using
the CTAB/P1223 template were shown in Fig. 2. Also,
the SAXS result was inserted in Fig. 2. The prepared particles have spherical
morphology and a clear SAXS peak indicating the presence of mesopores with a
uniform size which can be confirmed by the TEM image. As the same vein, we
investigated the effect of different dual templates such as CTAC/P123 on the
texture properties. More details in analysis and discussion will be presented.