Turning surface properties of Pd/N-doped porous carbon by trace oxygen with enhanced catalytic performance for selective phenol hydrogenation to cyclohexanone

Herein, the microstructure and surface properties of activated carbon (AC) was successfully turned by simply controlling the initial oxygen concentration during the calcination, the modified AC materials were doped with nitrogen and supported by Pd nanoparticles (NPs) to prepare Pd/N-doped porous carbon (Pd/CN) catalysts, and their catalytic performance in the phenol hydrogenation to cyclohexanone was evaluated. The modification with trace oxygen can decrease the hydrophilicity of AC, leading to better dispersibility of the Pd/CN-O catalyst in nonpolar reaction solvent (cyclohexane). Trace oxygen modification can increase the content of O-containing groups (C=O) on the AC surface, promoting the interaction between Pd NPs and carrier, thus higher Pd dispersion. As a result, the modified Pd/CN catalyst (Pd/CN-O) exhibits superior catalytic activity and stability than unmodified Pd/CN catalyst (Pd/CN-raw), with a phenol conversion increased from 84.1% to 99.6%. This work would aid the deep insights into the phenol hydrogenation over Pd/CN.