Easily recyclable pd-decorated hierarchically porous nanofibers for the selective hydrogenation of phenol

The electrospun nanofibers are good candidates for the catalyst carriers, however the fabrication of electrospun nanofibers with well-developed porous structures is still a big challenge. Herein, the SiO₂ nanofibers obtained by electrospinning and pyrolysis are functionalized with polydopamine (PDA) and UiO-66-NH₂, and after Pd loading the hierarchically porous Pd/UiO-SiO₂ nanofiber catalysts were developed. The surface properties and microstructures of the Pd/UiO-SiO₂ nanofiber catalysts were regulated by adjusting the concentrations of dopamine (DA) and zirconium tetrachloride (ZrCl₄), and the catalytic performance was tested in the selective hydrogenation of phenol to cyclohexanone. The as-prepared Pd/UiO-SiO₂-3–21.44 has abundant hierarchical pores and amino groups, high Pd content with good dispersion, and rich Pd(0), thus exhibiting a superior specific activity of 47.3 h⁻¹ higher than most Pd-based catalysts. Most importantly, the Pd/UiO-SiO₂-3–21.44 nanofiber catalyst can be directly taken out from the reaction solution and used for the next run, and has good catalytic stability.