Insight into the fast crystallization process of SSZ-13 Zeolite by addition of K+ cation

Abstract

Hydrothermal synthesis of SSZ-13 zeolite from precursors comprises many unanswered fundamental questions, in which understanding the effects of alkali metal cations on the structural rearrangement during the crystallizing period is an active and expanding area of research. Experimental results showed that the continuous crystallization process of SSZ-13 crystals can be easily hindered by the amorphous gel during the synthesis process. Accordingly, we carefully explored and repeated the crystallization period of SSZ-13 zeolite with different K+ mole ratios, which demonstrated significant effects on their crystallization behaviors with the easy breaking of amorphous gel state. The crystallization time was obviously shortened to 18 h. Theoretical calculation results also demonstrated that K+ cation in the precursor solution is more inclined to control the successive deprotonation process due to the higher activation energies for Si–O–Al bonds formation. Accordingly, the SSZ-13 zeolite sample tend to realize fast synthesis and transform into scattered crystals without aggregation by addition of K+ cation.