Chemistry Reference
In-Depth Information
Table 1
List and descriptions of zeolite structures discussed in this chapter.
Largest channel
dimension (Å)
4
Cross section of
channel (Å)
2
**
Channel
size
Material
Dimensionaliaty
3.8
3.8
CHA (SSZ-13)
3D
11.3
8-ring
EUO (EU-1)
1D
5.4
4.1
17.7
10-ring
MWW (MCM-22)
2D
5.5
4.0
17.7
10-ring
MTT (ZSM-23)
1D
5.2
4.5
18.4
10-ring
TON (ZSM-22)
1D
5.7
4.6
20.8
10-ring
MEL (ZSM-11)
3D
5.4
5.3
22.4
10-ring
MFI (ZSM-5)
3D
5.6
5.3
23.3
10-ring
IMF (IM-5)
3D
5.6
5.5
24.1
10-ring
TUN (TNU-9)
3D
6.0
5.2
24.5
10-ring
MOR (Mordenite)
1D
7.0
6.5
35.7
12-ring
*BEA (Beta)
3D
7.7
6.6
40.1
12-ring
AFI (SSZ-24)
1D
7.3
7.3
41.8
12-ring
*Disordered structures
**Cross-section calculated from the two perpendicular diameters of the largest channel,
assuming it to be perfectly elliptical.
Fig. 6 Illustration of the pore system in CHA zeolite.
shown. The blue (dark) color represents the accessible space inside the
pores, while the grey (light) color represents the outer limits of the pores.
The channel (pore) sizes described in this section are based on atomic
coordinates of the Type material and an oxygen radius of 1.35 Å, as
described by Meier et al.
7
The crystallographic free diameters of the
channels (interatomic distance vectors) are presented in Ångstrom
(10
10
meter) units.
Figure 6 displays the pore system of the CHA structure. It consists of
large cavities with 7.3 Å
12 Å dimensions that are connected by 8-ring
windows of 3.8
3.8 Å dimensions.
4
Figure 7 displays displays pore system of the one-dimensional 10 ring
zeolites, TON, MTT and EU-1, and two-dimensional zeolite MWW. The 10-
ring channels of TON are elliptical and slightly zigzag in shape, and have
dimensions 5.7
4.6 Å.
4,7
MTT has tear-drop shaped 10-ring channels
