Zeolites symmetry index

Later, more extensive TEM studies11351 suggested that the SBA-2 is an intergrowth of hep structure and cep structure. This phenomenon is similar with the case of intergrowth of EMT/FAU in zeolites. The intergrowth phases such as zeolite ZSM-3 and ZSM-20 were believed to be pure hexagonal phase initially. Even so, the index of XRD pattern with Edyinmc symmetry is still the most convenient method to identify SBA-2-type materials. 

The zeolites chosen for this study were CHA, FER, MFl, and HSAPO-34. Experimental geometries were used except as described below. To become active as catalysts or separators, the zeolites require some silicon atoms to be replaced with aluminum ions together with an extra-framework cation. In each case, one Si was substituted with Al. Several symmetry-unique T sites are available for substitution in each lattice, but the results of the current research—the effect of partial charge on Fukui index—are not expected to be strongly affected by the selection. T1 was used for CHA, T2 for FER, and T8 for MFI. Note that HSAPO differs from the first three conventional zeolites in that the lattice is formed from Al and P rather than Si. In this case, a Si atom was used at the T1 site to create an active structure. 

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