Quantcast

Organic-Free Interzeolite Transformation in the Absence of Common Building Units.

Research paper by Wei W Qin, Rishabh R Jain, Francisco F Robles Hernández, Jeffrey D JD Rimer

Indexed on: 21 Mar '19Published on: 12 Mar '19Published in: Chemistry - A European Journal



Abstract

Zeolite crystals can be used as seeds or aluminosilicate sources in syntheses to control polymorphs and/or reduce the quantity of organics used as structure-directing agents. A frequently invoked hypothesis for interzeolite transformations is that zeolites share some underlying similarity in structure, most notably in cases pertaining to organic-free syntheses. Here, we show for the first time that ZSM-5 (MFI) can be directly obtained from USY (FAU) through an interzeolite transformation between parent-daughter structures lacking common building units in the absence of a structure-directing agent and seeds. We show that interzeolite transformation leads to a crystalline product with fewer defects. Our findings also reveal that ZSM-5 is a metastable intermediate that undergoes further transformation to mordenite (MOR) and quartz. The MFI-to-MOR transition is counter to reported trends where transformations lead to structures with reduced molar volume. Herein, we propose mechanistic arguments that suggest the driving force for interzeolite transformation is more complex than guidelines posited in literature. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.