DEVELOPMENT OF MESOPOROUS MEMBRANE MATERIALS FOR CO2 SEPARATION Page: 4 of 8
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5.0 N NH4OH and 0.5 M Al(NO3)3.9H20 were mixed to form a solution. The solution
was added to distilled water in a dropwise fashion while the pH of the distilled water was kept at
6. The precipitated powders were centrifuged and dried at 70 C.
Al-sec-butoxide was dissolved in distilled water (mole ratio=1:100). Mix and stir @ 80 C
for 0.5h. Cool down to R.T., adjust pH-3, and add DBTA (weight ratio with A1203=1:1). Dry @
R.T. for 3-4 days.
Impregnation of Ba
A. 6.3 % mole barium nitrate was dissolved in water forming a solution.
B. The heat-treated alumina powder was impregnated with the above solution of barium
nitrate in water.
C. The marshy mixture was kept in oven at around 60-80 C till all the water evaporates.
The powder obtained was heat-treated at 400 C for 3 hours at the rate of 0.5 C/min.
Gas Chromatography (GC)
A. A GC column of approximate length 32 cm was filled with the silica powders
impregnated with Ba.
B. The column was kept at a temperature of 380 C with the injector and detector at a
slightly higher temperature of 395 C. This does the job of flushing away the gases
that may be present in the column.
C. The actual measurement was taken at a column temperature of 375 C. The flow rate
of carrier gas (helium) was maintained at 10 ml per 36-38 sec.
D. A mixture of N2 and CO2 (50/50) was passed through the column to determine the
difference in retention time between the two gases.
Results and Discussions
Preliminary results show that the templating method produced alumina with higher
surface area after 500 C heat treatment for 4 hours. Mesoporous alumina has surface area -380
m2/g compared to precipitated alumina with 240 m2/g. At 500 C heat treatment, it is found that
the addition of Ba lowers the surface area of alumina. This is reasonable since the effect of Ba on
the surface area is expected to occur near the y-a phase transition temperature (~1100 C) rather
than at 500 C. It is generally believed that stabilizing dopants can delay the y-a phase transition
temperature thereby avoiding the destruction of the high surface-area structure of the y phase.
However, there is an interesting difference between the Ba-doped mesoporous alumina and Ba-
doped precipitated alumina. For the precipitated alumina, Ba doping results in larger pore size
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Shih, Wei-Heng; Zhao, Qiang & Wang, Nanlin. DEVELOPMENT OF MESOPOROUS MEMBRANE MATERIALS FOR CO2 SEPARATION, report, May 1, 2002; Pittsburgh, Pennsylvania. (digital.library.unt.edu/ark:/67531/metadc740146/m1/4/: accessed October 21, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.