Density Functional Theory Study on the Re Cluster/HZSM-5 Catalysis for Direct Phenol Synthesis from Benzene and Molecular Oxygen: Active Re Structure and Reaction Mechanism

Abstract

DFT calculations have been achieved to obtain a convincing model for the active structure in a Re cluster/ HZSM-5 catalyst active for direct phenol synthesis from benzene and molecular oxygen. Re 10 clusters with interstitial N atoms composed of two Re octahedra edge-shared with each other were concluded as a stable active structure in agreement with the EXAFS analysis. The adsorption and behavior of benzene, oxygen atom and molecule and phenol on the Re cluster were examined to obtain the energy diagram for the phenol synthesis including intermediate and transition states, which explains the reaction steps for the phenol synthesis.

Transition‐Metal‐Catalyzed Synthesis of Hydroxylated Arenes

“…[47] The benzene oxidation is proposed to proceed through oxygen addition to a carbon atom of benzene to form an oxygen-added intermediate with a sp 3 carbon atom and subsequent insertion of the oxygen to the CÀH bond on the Re cluster. [48] On the other hand, a vanadium-substituted het-…”

Structure of the Active Platinum Cluster and Reaction Pathway of the Selective Synthesis of Phenol from Benzene and Oxygen Regulated with Ammonia on a Platinum Cluster/β‐Zeolite Catalyst Studied by DFT Calculations

“…In our previous computational study on the Re 10 edge‐sharing dioctahedral cluster with interstitial N atoms (Re 10 O 8 N 2 ), as shown in Figure , the initial step of the reaction was the dissociation of molecularly adsorbed oxygen to yield a bridge‐bonded oxygen atom and a terminal oxygen atom (O=Re). The energy profiles for the synthesis of phenol for the Re 10 O 8 N 2 cluster are also shown in Figure .…”

“… A model for Re 10 N 8 O 2 and the reaction profile for the synthesis of phenol from O 2 and benzene to yield phenol obtained by DFT calculations …”

“…A novel HZSM‐5 supported N‐interstitial Re cluster catalyst was found to exhibit a high phenol selectivity of 82.4 % by using O 2 as the sole oxidant at a benzene conversion of 5.8 % in the presence of NH 3 . The structure of the active Re cluster and its transformation during the catalytic synthesis of phenol inside the 3D pores of the HZSM‐5 zeolite were characterized by X‐ray absorption fine structure (XAFS), X‐ray photoelectron spectroscopy (XPS), solid‐state NMR spectroscopy, and temperature‐programmed desorption (TPD) and also discussed by DFT calculations …”

Supported Single Atom Catalysts for C−H Activation: Selective C−H Oxidations, Dehydrogenations and Oxidative C−H/C−H Couplings

“…NH 3 had a decisive role in the regeneration of the Re cluster from the resulting Re monomer after the reaction, an interesting observation that highlights the higher activity of clustered Re particles over single Re species. DFT and EXAFS investigations of the Re 10 clusters in the ZSM‐5 zeolite provided detailed information of the phenol synthesis steps [28] . The competitive co‐adsorption of oxygen and benzene was key in the mechanism.…”