Hydrothermal conversion of FAU into ∗BEA zeolites

The synthesis of ∗BEA zeolite was performed using two kinds of starting materials; dealuminated FAU zeolite and amorphous-silica/γ-alumina. When the amount of tetraethylammonium hydroxide (TEAOH) added as a structure-directing agent was small, a large difference in the crystallization rate was clearly observed, namely faster for FAU zeolite. This result strongly suggests that FAU zeolite is a useful starting material for the synthesis of ∗BEA zeolite. Moreover, the conversion of FAU zeolite into ∗BEA zeolite strongly depended upon the Si/Al ratio of the starting FAU zeolite. The ratio of TEAOH/SiO2 in the starting synthesis gel could be reduced to 0.1–0.15.