Hierarchically macro/mesostructured porous Au monoliths: simple synthesis, characterization and catalytic performance

Abstract

We report an efficient, highly selective and low-temperature three-dimensional hierarchically macro/mesostructured porous gold monoliths catalyzed reaction process for one-step oxidation of benzene to phenol with hydrogen peroxide as the green oxidant. The porous catalysts were characterized before calcination by FTIR and TGA and after calcination by XRD, FESEM-EDX and BET techniques. The selectivity of phenol production from the one-step oxidation of benzene over porous gold catalysts can be enhanced by concise tuning of pore diameter and pore surface morphology. From the results obtained, it was concluded that the balance between the decomposition rate of H2O2 and benzene adsorption over the catalyst surface is responsible for the outstanding catalytic performance of the three-dimensional macro/mesoporous gold monoliths. The as-synthesized series of nanoporous gold monoliths were evaluated for the first time as alternative heterogeneous catalysts for the direct catalytic oxidation of benzene to phenol at low temperature. Therefore, it is of great interest to “switch-off” other time- and energy-consuming reactions and promote the hydroxylation of benzene with porous Au catalysts.