Use of modified zeolites as reagents influencing nucleation in zeolite synthesis

Abstract

Publisher Summary This chapter presents the use of modified zeolites as reagents influencing nucleation in zeolite synthesis. Two types of zeolite synthesis reactions are studied. In the first type, reactions were performed using calcined boron-beta zeolite as borosilicate source, a quaternary ammonium hydroxide compound, sodium hydroxide, water, and additional boron from sodium borate. In the second type of reaction, Cabosil M5 or N silicate was mixed into a solution of the two bases mentioned above and aluminum was provided as FAU zeolite, which in most instances was modified by ion-exchange with a transition metal. Care was taken to monitor the pH of the exchange to avoid precipitation from the hydrolysis of the hydrated cation. Highly porous zeolites, such as FAU and boron-beta are useful reagents for delivering A1 and B to growing organosilicate lattices during synthesis. The high-surface areas of these reagents allow for rapid interaction with the synthesis solution providing for attractive nucleation rates. The way in which components are delivered to the nucleation site (by an unknown mechanism) can also alter the phase selectivity in the experiment.