Engineering of PtZn@S-1 Using an Alkali-Acid Pair Strategy: Applied for Ethane Dehydrogenation

Developing synthetic strategies for high-quality metal-zeolite composites is critical for achieving advanced catalytic performances. One major challenge lies in addressing the rate mismatch between rapid metal deposition and slow zeolite crystallization, which leads to the segregation of large metal particles. Herein, we propose a universal strategy via quaternary ammonium alkali-metallic acid (QAMA) pairs for fabricating highly dispersed metal@zeolite materials with nearly 100% metal (Ru, Ir, Pd, Pt, and Zn) utilization. Using tetrapropylammonium hydroxide (TPAOH) as both a structural-directing agent and basic medium, the interaction of TPA⁺ with acidic metal precursors forms the “QAMA” pairs, which inhibit the precipitation of metal precursors and guide their dispersion into the 10-membered ring channels of MFI topology. Furthermore, the appropriate Si-OH groups on the silicalite-1 (S-1) seeds surface anchor the “QAMA” pairs and thus assist in the subnanometer PtZn particle dispersion. A series of PtZn@S-1 catalysts exhibited outstanding catalytic activity (14.1 mol_C2H4·g_Pt^-1·h^-1 at 24 h^-1 weight hourly space velocity (WHSV)) and stability (K_d = 0.0004 h^-1) in ethane dehydrogenation (EDH), particularly at relatively low temperature (550 °C) with pure ethane feed.