Highly stable encapsulated Ni catalyst for phenol hydrogenation: Synthesis and mechanistic insight

Although supported Ni catalysts exhibit potential for fixed-bed applications, traditional systems suffer from rapid deactivation. Herein, we demonstrate a highly stableencapsulated Ni@silicalite-1 catalyst synthesized via chelator-free hydrothermal route.

Comparedto conventional impregnated Ni/silicalite-1 counterparts, Ni@silicalite-1 maintains exceptionaloperational stability beyond 100 h with sustained phenol conversion exceeding 98% and cyclohexanol selectivity over 95% under continuous-flow conditions. Characterization results includingX-ray absorption spectroscopy, in-situ diffuse reflectance infrared Fourier transform spectroscopyand high angle annular dark field scanning transmission electron microscopy reveal that ultrafineNi nanoparticles (~2.34 nm) anchored via Ni-O-Si interfacial bonds constitute the active sites, conferring dual resistance to thermal sintering and carbon deposition under reaction conditions.Mechanistic studies tracking silicalite-1 crystallization demonstrate that amorphous nickel silicateprecursors gradually transform into spatially confined Ni nanoparticles driven by the organic template.