Geoscience Reference
In-Depth Information
Figure 6.45 The H
2
O
adsorption isotherms for AlPO
4
-
5, -11, -17, and -20
[129]
.
Na-X
0.35
AlPO
4
-20
AlPO
4
-5
AlPO
4
-17
0.30
0.25
0.20
AlPO
4
-11
0.15
0.10
0.05
Silicalite
0
0.2 0.4 0.6
Relative pressure (
P
/
P
o
)
0.8
1.0
Table 6.21 Adsorption Capacity of Molecular Sieves at P/Po
5
0.4
[131]
Kinetic Diameter (
˚
)
Adsorbate
a
Capacity (cm
3
/g)
AlPO
4
-5
VPI-5
3.46
O
2
0.146
0.228
4.30
n-Hexane
0.139
0.198
6.00
Cyclohexane
0.145
0.156
6.20
Neopentane
0.137
0.148
8.50
Triisopropylbenzene
a
Adsorption at room temperature except for O
2
which was performed at either liquid N
2
or O
2
temperatures.
are shown in
Figure 6.46
. Thus, the zeolites with large pore diameters are becom-
ing essential materials for the adsorption of large molecules, which either absorb or
adsorb very slowly into known molecular sieves.
6.10 Oxidative Catalysis on Zeolites
Oxidation processes constitute one of the most common classes of chemical reac-
tions. The endeavor by investigators to create economically more effective and
ecologically clean technologies has stimulated the search for new catalysts exhibit-
ing a high selectivity.
