Understanding the selective synthesis of siliceous zeolite encaged metal particles [dataset]

Encapsulating metals within silica "nanoboxes" offers unique opportunities for controlling catalytic reactions through nanoscale diffusion effects. Here, we systematically investigated the synthesis parameters governing the formation of metalencaged hollow silicalite-1, examining the influence of hydrothermal treatment time, synthesis conditions, additives, metal precursor identity, and turbulence. Statistical analysis of hollow structure-types from large-scale TEM datasets enabled robust quantification of structural distributions, revealing selectivities (often overlooked in the literature but critical for catalytic application). Optimisation of synthesis conditions enabled the preparation of both multihollow (MH) "sponge-like" structures and single-hollow (SH) nanoboxes with selectivities of up to 84% and 72%, respectively. Nitrogen physisorption and solid-state NMR provided complementary signatures of these different hollow architectures: SH-rich samples exhibited a characteristic low-pressure hysteresis loop and lower Q³/Q⁴ ratios, the latter consistent with reduced framework defect concentrations, whereas "sponge-like" MH-rich samples displayed pronounced mesoporosity centred at 5-6 nm. Finally, vapour-phase furfural hydrogenation was used as a test reaction to demonstrate that hollow-structure morphology influences catalytic selectivity, highlighting the role of architecture-dependent diffusion effects and providing a foundation for the rational use of encaged metal particles in catalysis.