Two Coexisting Forms of Simple Molecules for Directing Sesqui-Unit-Cell Zeolite Nanosheets

Feasible strategies are desirable for preparing zeolitic nanosheets with opener porosities and more accessible active sites. Highly delaminated FER nanosheets (ECNU-17) with unit-cell scale thickness were hydrothermally synthesized using a simple, small, and low-cost imidazole molecule as the sole organic structure-directing agent (OSDA). The single OSDA directed the formation of the FER framework, while the π-πstacked OSDAs terminated the growth perpendicular to the zeolite sheets. The ECNU-17 nanosheet is only 2.9 nm in thickness, corresponding to one and a half FER unit cells along a-axis. With open hierarchical porosity and an enhanced external surface area of 253 m2 g-1, ECNU-17 is endowed with improved mass transport and a significantly increased number of active acid sites accessible to bulky organic molecules. The ultrathin sheets of ECNU-17 aluminosilicate display excellent activity and selectivity for the protection reaction of benzaldehyde with pentaerythritol as well as the cracking of 1,3,5-triisopropylbenzene.