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.