Thermally-Stable Single-Site Pd on CeO2 Catalyst for Selective Amination of Phenols to Aromatic Amines without External Hydrogen.

Developing a new route to produce aromatic amines as key chemicals from renewable phenols is a benign alternative to current fossil-based routes like nitroaromatic hydrogenation, but is challenging because of the high dissociation energy of the Ar-OH bond and difficulty in controlling side reactions. Herein, an aerosolizing-pyrolysis strategy was developed to prepare high-density single-site cationic Pd species immobilized on CeO₂ (Pd₁/CeO₂) with excellent sintering resistance. The obtained Pd₁/CeO₂ catalysts achieved remarkable selectivity of important aromatic amines (yield up to 76.2 %) in the phenols amination with amines without external hydrogen sources, while Pd nano-catalysts mainly afforded phenyl-ring-saturation products. The excellent catalytic properties of the Pd₁/CeO₂ are closely related to high-loading Pd single-site catalysts with abundant surface defect sites and suitable acid-base properties. This report provides a sustainable route for producing aromatic amines from renewable feedstocks.