Selective Hydrogenation of Phenols to Cyclohexanones Over Hydrotalcite-Supported Pd Single-Atom Catalyst.

Cyclohexanones are widely used chemicals and currently produced by the oxidation of the fossil feedstocks. Direct selective hydrogenation of lignin derivatives has great potential for producing these chemicals, but is challenging to obtain high yields. Here, we report that hydrotalcite-supported Pd single-atom (Pd/CHT-800) catalyst enabled the hydrogenation of the benzene ring in the aromatics without the overreaction of carbonyl group, which could afford >99.9% yield of cyclohexanones using water as the reaction medium. The reaction mechanism was systematically studied by the control experiments and detailed in situ characterizations. In the Pd/CHT-800 catalyst, the Pd-O-MgAl sites were formed, and the cooperation of the Pd atoms and calcined CHT material could not only realize the aromatic hydrogenation efficiently, but also inhibit the hydrogenation of the carbonyl group in the reaction effectively. This work provides a novel route for the sustainable production of cyclohexanones.