| Abstract
| - An aluminosilicate zeolite with IFR topology can be synthesized in a wide range of Si/Alratios (Si/Al ≥ 20) using benzylquinuclidinium as a structure-directing agent in the presenceof fluoride anions. The phase selectivity of the crystallization depends on both the Al andthe water content of the synthesis mixture, and by adjustment of the degree of dilution ofthe mixture, it is also possible to obtain zeolite Beta. The isomorphous substitution of Si byAl in the IFR framework and the acidity of the calcined zeolite has been confirmed by anumber of physicochemical techniques. The calcined IFR material contains acid sites ofmedium strength with large pores and a large void volume. Partial dealumination occursduring calcination, but N2 and pyridine adsorption experiments do not indicate any poreblocking. The aluminosilicate IFR zeolite contains unusual acid sites that are involved inrelatively strong hydrogen bonds. Besides the well-known 1H NMR chemical shift for acidsites at 3.9 ppm and the IR band at 3629 cm-1, the hydrogen-bonded acid sites arecharacterized by 1H NMR chemical shifts of 5.2 and 6.3 ppm and a broad unresolved IRband at 3488 cm-1.
|
