Pd Nanoparticles Supported on Hierarchically Porous Carbon Nanofibers as Efficient Catalysts for Phenol Hydrogenation

Abstract

One-step hydrogenation of phenol is a preferable and economic route for preparing cyclohexanone. The development of catalysts with high catalytic performance and easy recovery still keeps a significant challenge. Herein, the novel ZIF-derived hierarchically porous carbon nanofibers (ZCNFs) were fabricated by electrospinning and calcination with ZIF-67 as the nanoparticles precursor and PAN as the CNFs precursor, and they were used as the supports of Pd nanoparticles for preparing the Pd@ZCNFs-x catalysts [x is the mass ratio of ZIF-67 to PAN (%)]. Pd@ZCNFs-20 exhibits superior catalytic performance in the phenol hydrogenation to cyclohexanone, and its catalytic activity is 2.2 times higher than that of Pd@ZCNFs-0. The ZIF-67 doping is in favor of the formation of ZCNFs with more defects, larger surface area, hierarchical pore structure, higher N content and better Pd dispersion, thereby improving the catalytic activity. Furthermore, the as-prepared Pd@ZCNFs-20 catalyst is easy to be recovered from the reaction mixture due to its one-dimensional structure, and shows good reusability during six reaction cycles. In view of the high catalytic performance and reusability of the Pd@ZCNFs catalysts, the developed hybrid ZCNFs are potential candidates for the phenol hydrogenation. The ZIF-67 doping is in favor of the formation of ZIF-derived hierarchical porous carbon nanofibers (ZCNFs) with more defects, larger surface area, hierarchical pore structure, higher N content and better Pd dispersion, thereby improving the catalytic activity of Pd@ZCNFs in the phenol hydrogenation to cyclohexanone.