Embryonic zeolite-directed synthesis of ZSM-34 and SSZ-13 zeolites

Abstract

The use of an organic structure-directing agent (OSDA) makes zeolite synthesis expensive and environmentally non-friendly. Seeded zeolite synthesis offers an environmentally benign alternative that avoids using an OSDA while providing a high purity, crystallinity, and yield in the product. In this study, we report using embryonic zeolites (EZs) as efficient seeds to obtain industrially important zeolites such as ZSM-34 and SSZ-13 in an OSDA-free synthesis system. Our results showed that zeolites ZSM-34, SSZ-13 and LTL could be obtained depending on the Al/Si ratio in the synthesis system. The synthesis time was considerably shorter than other ZSM-34 and SSZ-13 syntheses methods reported in the literature, achieving more than 90% crystallinity. The physicochemical analysis showed that highly crystalline zeolites with characteristics similar to the OSDA synthesized counterparts were obtained. Furthermore, the EZs seeding approach is facile, low cost, and environmentally friendly, provided the synthesis is OSDA-free. In addition, the EZs seeds can be obtained under hydrothermal synthesis conditions. The method can be potentially applied to the synthesis of other zeolite types.