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

4 Results and discussion
20 30 40 50 60
2Theta [º]
Figure 54 XRD diffraction patterns of dried ZrO2 sols calcined at 140, 400, 500, 600ºC. The crystal size
determined with the Scherer equation is presented in the inlay.
4.3.2.4 Amine approach - Binary oxides Ti1-xZrxO2
The TiO2 addition into the ZrO2 was conducted in the first stage of the powder formation
by mixing the alkoxides so it can be assumed that, after the sol-gel formation, a
homogeneously distributed TiO2 in the ZrO2 network. Transmission Electron Microscopy
- Energy Dispersive using X-ray analysis and Inductively Coupled Plasma
measurements 116 were performed and found similar metal oxide ratios as starting
mixtures supporting this assumption.
Type I N2-sorption isotherms are observed for the Zr-rich binary oxides calcined at 500ºC
(Figure 55). The specific surface area increases and the pore size decrease with increasing
the mol% TiO2 in ZrO2 (0 and 25% in Table 25 and Figure 56-A).
Doping TiO2 with 10 and 25 mol% ZrO2 calcined at 500ºC resulted in combination of
type I and IV isotherms. The relative microporous adsorbed volume Vmicro/Vtotal increases
and pore size decreases with increasing ZrO2 content (Figure 56-B).
All the binary oxides contain significant relative microporous absorbed volume at 500ºC.
This was expected from the linear polymeric sols. The N2-sorption isotherm of
Ti0.5Zr0.5O2 sample calcined at 400ºC is comparable to what has been reported in
literature of Ti0.66Zr0.34O2 80 and Ti0.8Zr0.2O2. 83 The highest specific surface area, the
highest relative microporous absorbed volume and the smallest estimated pore size in this
study is obtained for Ti0.5Zr0.5O2 calcined at 500ºC (Table 25 and Figure 56). XRD
87
600ºC
500ºC
400ºC
Crystal size [nm]
140ºC
25
20
15
10
5
0
400 500
T [ºC]
600