Pd-Decorated Hierarchically Porous Carbon Nanofibers for Enhanced Selective Hydrogenation of Phenol

Aiming at the design and preparation of high-efficiency catalysts for the selective hydrogenation of phenol, the hierarchically porous Pd@CNF catalysts were fabricated by oxygen-activating ZIF-67/PAN composite nanofibers with O₂ as the oxidant during high-temperature pyrolysis, followed by acid etching and Pd loading. Appropriate initial oxygen concentration and Co²⁺ molar concentration are conducive to the fabrication of hierarchically porous carbon nanofibers (CNFs) with a high mesopore and macropore ratio, increased ether-type oxygen content, and good one-dimensional (1D) morphology, which enhance the dispersion and anchoring of Pd, increase the strength of basic sites and H₂ adsorption, and improve the mass transfer and dispersibility in cyclohexane. The corresponding catalyst Pd@CNFs-0.1-0.2 exhibits excellent phenol hydrogenation performance with a turnover frequency value of 66.6 h^-1, which is 6.3 times that of Pd@CNFs-0.1-1 and 2.4 times that of Pd@CNFs-0.1-0. Furthermore, the 1D morphology of Pd@CNFs-0.1-0.2 enables the rapid recovery and recycling of the catalyst. This work provides a new direction for the development of efficient and easy-to-recover phenol selective hydrogenation catalysts.