Synthesis and characterization of the 12-ring zeolites UZM-4 (BPH) and UZM-22 (MEI) via the charge density mismatch approach in the Choline-Li20-Sr0-Al203-Si02 system

摘要

The Charge Density Mismatch (CDM) approach to zeolite synthesis employs zeolitic reaction mixtures which cannot easily crystallize, which are then perturbed by the addition of small amounts of crystallization-inducing agents to achieve crystallization. This approach allows great control over crystallization and extends the utility of any organic template. In this work, choline hydroxide derived aluminosilicate solutions were treated with solutions containing Li+, Sr +, or both, resulting in the isolation of useful forms of the structurally similar 12-ring zeolites UZM-4 (BPH) and UZM-22 (MEI),, UZM-4 is isolated in the Li-Choline system at Si/Al = 2 66, the highest ratio achieved by direct synthesis,, UZM-22 is the first example of an MEI aluminosilicate prepared with a simple organic template, making this an accessible material.