Green Synthesis of Ultrathin MWW Zeolites With Tunable Al‐T Sites Using Nitrogen‐Free Secondary OSDAs for Catalytic Cracking

Abstract

ABSTRACT The direct synthesis of ultrathin MWW zeolites with precisely controllable aluminum location represents a significant challenge. Herein, we report a sustainable approach using cycloketones as secondary nitrogen‐free organic structure‐directing agents (NF‐OSDAs) to fabricate two‐dimensional (2D) MWW zeolites. Cyclobutanone (Cy4) directs the formation of ultrathin nanosheets featuring expanded interlayer spacing and tunable aluminum distribution. We demonstrate that Na + ‐cycloketone complexes selectively occupy specific pore environments, effectively reducing the population of T 6 –T 7 framework aluminum (Al F ) sites and migrating to T 2 Al F sites, promoting external Brønsted acidity. The resulting Cy4‐MWW catalyst exhibits outstanding performance in bulky‐molecule transformations. Mechanistic studies reveal that cycloketones undergo in situ self‐condensation to generate dimeric species that function as pivotal structural directors. Their steric presence affects layer thickness and nanosheet packing, whereas their Na + ‐coordinated forms strongly interact with T 2 Al F sites, thereby driving aluminum migration from the confined T 6 –T 7 Al F positions to accessible T 2 Al F sites. This strategy exhibits broad versatility across a range of cycloketones (Cy4–Cy10), enabling the concurrent tuning of both the MWW architecture and its aluminum distribution.