(690g) Critical Factors Governing the Design of Self-Pillared Zeolite ZSM-5 Nanosheets

Hierarchical zeolites have emerged as high-performance nanoporous materials owing to their superior mass transport properties compared to conventional zeolites used in numerous commercial applications. Methods to synthesize hierarchical zeolites typically require costly organic reagents, multi-step processes, and/or conditions leading to low product yields. We have shown that seed-assisted synthesis in organic-free media can generate self-pillared pentasil (SPP) zeolites comprising five-membered ring zeolites (largely ZSM-5) where nanosheets possess dimensions that are smaller than most state-of-the-art MFI-type zeolites [1]. The process used to synthesize SPP is commercially viable and achieves physicochemical properties and catalytic performance that far exceed conventional counterparts.

In this presentation, we will discuss how synthesis parameters such as the structure of zeolite crystal seeds, the judicious selection starting reagents, and the inclusion of organic structure-directing agents (OSDAs) can impact the kinetics and final properties of aluminosilicate SPPs. Our findings reveal that specific composite building units (CBUs) of shared by zeolite seeds and the ZSM-5 (MFI) product impact the degree to which pillaring occurs during interzeolite transformation. Attempts to rationalize seed-assisted SPP synthesis include the use of descriptors, such as the structural similarity between seeds and SPP, where we find limited correlations that can be used to predict the formation of hierarchical products. We will discuss these results along with detailed investigation into the effect of local microstructure on zeolite nucleation and growth using a combination of characterization techniques. These studies collectively identify new routes to rationally design hierarchical materials through seed-assisted zeolite synthesis – an area of research where current knowledge gaps limit fundamental understanding of crystal growth mechanisms.

References:

[1] Jain, R., Chawla, A., Linares, N., Garcia Martinez, J., Rimer, J.D.: “Spontaneous Pillaring of Pentasil Zeolites” Adv. Mater. 33 (2021) 2100897