Crucial Factors for Seed-Directed Synthesis of CON-type Aluminoborosilicate Zeolites Using Tetraethylammonium

Abstract

Designing efficient synthesis methodologies, without using expensive organic structure-directing agents (OSDAs), for industrially important zeolites is of high significance not only to realize their commercialization but also to control their structural properties. Herein, we present a systematic study on seed-directed synthesis of aluminoborosilicate CON-type zeolites using tetraethylammonium hydroxide (TEAOH) as a simple OSDA, by particularly focusing on the precise size control of CIT-1 seeds, which allowed us to improve the overall production efficiency and to reach the highest solid yield of 38 wt %. It is revealed that the use of a certain amount of seeds jointly with TEAOH is the key factor governing the synthesis, where seeds act as growth centers to promote the crystallization, while TEAOH stabilizes the structure by charge-compensating with framework atoms. These findings provide insight into the synthesis of multipore structures from simple OSDA, which can be further extended to many other systems currently requiring complex OSDAs.