Relationships between Phenol Production Activities and Lewis Acid Sites of Cu/HZSM-5 Catalyst for Gas-phase Aerobic Benzene Oxidation

Abstract The currently used cumene method of producing phenol is a multistep reaction that requires costly production facilities and a large amount of energy, and thus, a simpler, greener method of phenol production must be developed. This study investigates the acidic properties of HZSM-5 and redox cycle of Cu to examine the mechanism of phenol formation via the gas-phase catalytic oxidation of benzene over the Cu/HZSM-5 catalyst. Pyridine adsorption Fourier transform infrared spectroscopy suggests that calcination at a high temperature (1273 K) leads to the dealumination of Cu/HZSM-5, and extra-framework Al increases the number of Lewis acid sites, which function as benzene activation sites. Photoluminescence spectroscopy indicates that the redox cycle of Cu comprises the reduction of Cu 2+ to Cu + by benzene and the oxidation of Cu + to Cu 2+ by O 2 . Based on these results, the mechanism of phenol formation from benzene is inferred, and this study paves the way for the establishment of the economical, green industrial synthesis of phenol. Fullsize Image