Silanols-stabilized zinc cations in self-pillared pentasil zeolite as an efficient catalyst for direct propane dehydrogenation

Propane dehydrogenation (PDH) offers a promising route for on-demand propylene production, yet developing cost-effective and durable non-noble metal catalysts remains challenging. Herein, we report a silanol (Si–OH) stabilized Zn catalyst supported on hierarchical self-pillared pentasil (SPP) zeolite, synthesized via the metal-ligand protection strategy under one-pot hydrothermal condition. The abundant isolated silanol groups on the SPP framework effectively anchor Zn²⁺ ions, forming highly dispersed subnanometric ZnO clusters confined within zeolite channels without forming bulk particles. Structural characterization (powder X-Ray diffraction (PXRD), Fourier transform infrared (FTIR), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), X-ray photoelectron spectroscopy (XPS)) confirms the atomic-level dispersion of Zn species and their strong interaction with silanol defects. At an optimal Zn loading of 2.65 wt.%, the catalyst achieves 33.7% propane conversion with 92.7% propylene selectivity and a space-time yield of 179.9 mg·g⁻¹·h⁻¹ at 550 °C under a weight hourly space velocity (WHSV) of 0.6 h⁻¹. Remarkably, the catalyst retains > 90% selectivity and recovers 80% initial activity after two regeneration cycles, attributed to minimized coke deposition (< 0.3 wt.%) and suppressed Zn loss. Mechanistic studies reveal that silanol-mediated Zn stabilization optimizes propane C–H activation, while the hierarchical porosity of SPP enhances mass transport and coke resistance. This work underscores the critical role of support surface chemistry and architecture in designing robust propane dehydrogenation (PDH) catalysts, offering a viable pathway to replace conventional noble or toxic metal-based systems.