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.