Sustained Sn Release Enables Rapid Synthesis of Hierarchical Sn-SPP Zeolites with a Reinforced Architecture and Enhanced Stability

Hierarchical Sn-containing self-pillared pentasil (Sn-SPP) zeolites, with their unique nanosheet intergrowth architecture, are highly attractive for biomass upgrading. However, direct Sn incorporation is hindered by kinetic mismatches between Sn and Si. Premature Si–O–Sn linkages disrupt the ordered nucleation, resulting in sluggish crystallization, poor Sn integration, and a loosely stacked, unstable structure. Herein, we report a “sustained Sn release” strategy using tetraethylenepentamine (TEPA) as a multifunctional additive. TEPA transiently coordinates Sn species into soluble complexes, creating a sustained-release reservoir that mediates TEPA-mediated Sn buffering to prevent premature Si–O–Sn formation and enables silicate preorganization. Simultaneously, TEPA cotemplates with TBAOH to direct denser nanosheet stacking, reducing external defects and reinforcing framework integrity. This dual-function mechanism expands the synthesis window to Si/Sn = 50, shortens crystallization time from weeks to days, and tolerates reduced structure-directing agent loadings. The resulting Sn-SPP achieves 75.3% glucose conversion with 81.1% fructose selectivity in glucose isomerization, outperforming conventional microporous Sn-MFI. Moreover, it retains >95% crystallinity and acid site density after harsh steaming. This work establishes a cotemplating approach for hierarchical zeolites that couples kinetic regulation of heteroatom speciation with structural control.