Formation of beta-quartz solid solution from Zn-exchanged zeolite A

beta -quartz solid solution consisting of zinc aluminocilicate was prepared from a Zn-exchanged zeolite A (Zn-A) as a precursor. In the thermal-transf ormation process of Zn-A, two kinds of beta -quartz solid solutions were ob tained. Zn-A became an amorphous material upon heating at 873 K. The beta - quartz solid solution (beta -Qss(Z)), which has a composition close to that of Zn-A (ZnAl2Si2O8), formed with the presence of small amounts of gahnite and mullite from the amorphous material at temperatures above 1163 K. The beta -Qss (Z) decomposed at temperatures above 1223 K and then another beta -quartz solid solution (beta -Qss (S)) formed. The composition of beta -Qs s (S) was richer in SiO2 than that of beta -Qss (Z). The d value in the (10 1) plane of beta -Qss (S) decreased with increasing heating temperature, wh ich suggested that the amounts of Al and Zn in the specimen decreased and t hat beta -Qss(S), formed above 1573 K, has the composition of nearly pure S iO2.