Enabling Specific Benzene Oxidation by Tuning the Adsorption Behavior on Au Loaded MgAl Layered Double Hydroxides

Abstract

AbstractDirect and selective oxidation of benzene to phenol is a long‐term goal in industry. Although great efforts have been made in homogenous catalysis, it still remains a huge challenge to drive this reaction via heterogeneous catalysts under mild conditions. Herein, a single‐atom Au loaded MgAl‐layered double hydroxide (Au1‐MgAl‐LDH) with a well‐defined structure, in which the Au single atoms are located on the top of Al3+ with Au‐O4 coordination as revealed by extended x–ray–absorption fine–structure (EXAFS)and density–functional theory (DFT)calculation is reported. The photocatalytic results prove the Au1‐MgAl‐LDH is capable of driving benzene oxidation reaction with O2 in water, and exhibits a high selectivity of 99% for phenol. While contrast experiment shows a ≈99% selectivity for aliphatic acid with Au nanoparticle loaded MgAl‐LDH (Au‐NP‐MgAl‐LDH). Detailed characterizations confirm that the origin of the selectivity difference can be attributed to the profound adsorption behavior of substrate benzene with Au single atoms and nanoparticles. For Au1‐MgAl‐LDH, single Au‐C bond is formed in benzene activation and result in the production of phenol. While for Au‐NP‐MgAl‐LDH, multiple AuC bonds are generated in benzene activation, leading to the crack of CC bond.