Geoscience Reference
In-Depth Information
n-paraffins and n-olefins (which entered the Ca-A) were readily combusted with
O
2
, while isoparaffins and isoolefins, which did not enter Ca-A, did not react
appreciably
[151]
. Shape-selective catalysis has also been observed in several other
zeolites and prominent among them is ZSM-5 and MFI. This sorbs and cracks
monomethyl in addition to n-paraffins and is used to dewax heavy oils.
Mirajkar et al.
[152]
have studied the sorption properties of Al-omega and Ga-
omega zeolites.
Figure 6.41
shows the sorption uptakes (P/Po
0.8, 298 K) of
samples of different crystallinity for Al-omega and Ga-omega zeolites synthesized
at 398 K. These curves typically show that the sorption uptake increases as the
degree of crystallinity increases; water being a polar molecule and comparatively
small in size, it is able to become occluded in cavities of samples of low crystallin-
ity.
Table 6.19
gives the adsorption (wt%) on Al- and Ga-omega zeolites:
P/Po
5
0.8 and T
298 K.
5
5
20
4
16
3G
1A
1G
3
4A
12
3A
2A
2
8
4G
1
2G
4
0
20
40 60
% Crystallinity
80
100
% Crystallinity
(a)
(b)
Figure 6.41 (a and b) Sorption uptakes (P/Po
5
0.8, 298 K) of samples of different
crystallinity for Al-omega and Ga-Omega zeolites synthesized at 398 K
[152]
.
Table 6.19 Adsorption (wt%) on Al- and Ga-Omega Zeolites, P/Po
5
0.8 and T
5
298 K
[152]
Synthesis Temperature (K)
Al-Omega
Ga-Omega
383
398
413
383
398
413
Adsorbate water
20.45
18.10
17.30
17.50
14.89
15.3
n-Butylamine
17.19
13.22
10.10
15.50
11.69
9.6
n-Hexane
6.70
3.51
2.09
4.70
3.57
1.8
Cyclohexane
6.50
3.33
2.25
4.61
2.27
1.8
