Selective phenol hydrogenation to cyclohexanone over Pd@N-doped porous carbon: role of storage under air of recovered catalyst

The effect of storage method of used Pd@N-doped porous carbon (Pd@CN) on its catalytic stability in the phenol hydrogenation to cyclohexanone was studied. The experimental results highlighted that the storage method strongly affected the catalytic stability of Pd@CN. The phenol conversion significantly reduced from 88 to 33.8% when the recovered catalyst was dried under air atmosphere at room temperature, owing to the formation of macromolecules originated from the oxidation of cyclohexanone, the reduction of the amount of pyridine N and C–O groups. The adsorption of phenol and cyclohexanol on the Pd@CN catalyst was not responsible for its deactivation. As the recovered Pd@CN catalyst was stored under N₂ atmosphere at room temperature, its catalytic activity could be remained.