Switchable cyclohexanone/cyclohexanol selectivity in room temperature aqueous hydrogenations of phenol using Au–Pd nanoparticles supported on a bimodal cubic N,S-doped mesoporous carbon

A novel catalyst system was synthesized containing well-dispersed Au–Pd nanoparticles embedded within a bimodal N, S-doped ordered mesoporous carbon (Au–Pd@IBOMC) for the selective hydrogenation of phenol. Various analytical techniques were utilized to comprehensively characterize both chemical and structural features of Au–Pd@IBOMC. These methods included N2 adsorption-desorption analysis, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), elemental mapping, energy-dispersive X-ray spectroscopy (EDX), low-angle X-ray powder diffraction (LA-XRD), X-ray photoelectron spectroscopy (XPS), thermal gravimetric analysis (TGA), and elemental analysis. The catalyst displayed excellent catalytic efficiency and notable temperature-dependent selectivity during phenol hydrogenation under mild reaction conditions in water as a reaction solvent. A selectivity switch from cyclohexanone to cyclohexanol could be observed by reducing the temperature from 70 to 25 °C in water as a solvent. The comparison between this catalyst and monometallic gold or palladium catalysts has demonstrated the substantial influence of the second metal in bimetallic systems on the hydrogenation of phenol. Additionally, the morphology, heteroatom doping, and surface functionality of carbon support played crucial roles in determining catalyst activity for this particular reaction. © 2024