Inorganic Microporous Membranes for Gas Separation in Fossil Fuel ...

4 Results and discussion
A) 8YSZ membrane
Excitation: 514.5 nm; 20.6 mW
Raman Intensity
Al 2 O 3
380
cubic YSZ
262
400 380 360 340 320 300 280 260 240 220 200
Wavenumber/cm -1
cubic YSZ
225
98
Raman Intensity
Al-O-Zr
1155
B) 8YSZ membrane
Excitation: 514.5 nm; 20.6 mW
cubic YSZ
1050
cubic YSZ
1033
1200 1180 1160 1140 1120 1100 1080 1060 1040 1020
Wavenumber/cm -1
Figure 65 A and B Raman spectra of the 8YSZ layer that contained F127, acetyl acetone and caproic acid
in the sol.
4.3.3.2 Amine approach - TiO2-ZrO2 and binary oxide layers
TiO2, ZrO2 and 50 mol % TiO2 in ZrO2 layers are prepared on γ-Al2O3 membranes. The
films are prepared by spin or dip coating using the as-made DEA sols. The amount of
mesoporous defects in the final membrane layer was minimised by consequently coating
each γ-Al2O3 membrane twice with the DEA sol. The first DEA layer was calcined
before applying the second DEA layer. The layer thickness of the intermediate layer and
the final membrane layer is observed with SEM and TEM. 20-40 nm homogeneous thin
films have been observed for the membrane layers prepared from TiO2, ZrO2 and
Ti0.5Zr0.5O2 calcined at 400, 500 and 600ºC (Table 27 and Figure 67 A-C).
The infiltration depth of DEA sols was studied by means of Secondary Ion Mass
Spectroscopy (SIMS). A penetration depth into the γ-Al2O3 was approximately half the
final membrane layer thickness, considering the TiO2, ZrO2 and Ti0.5Zr0.5O2 layers
calcined at 500ºC. Titanium and zirconium atoms were found at a distance of 10-15 nm
from the Ti0.5Zr0.5O2 – γ-Al2O3 boundary for the Ti0.5Zr0.5O2 membrane with a thickness
of 25 nm.
Table 27 Intermediate and final membrane layer thickness
Calcination mol% Ti Thickness γ-Al2O3 in µm Thickness Final layer in
temperature
nm by TEM
400ºC 50 2.5 20-30 (SEM)
0 5.8 36
500ºC 50 2.6 25
100 2.4 22
600ºC 50 4.5 23