Synthesis of Mesoporous PdxCu1–x/Al2O3-y Bimetallic Catalysts Via Mechanochemistry for Selective N-Formylation of Amines with CO2 and H2

We herein reported an effective strategy for the preparation of bimetallic mesoporous catalysts PdxCu1–x/Al2O3-y via mechanochemistry. The resulting Pd0.25Cu0.75/Al2O3 catalyst showed excellent catalytic activity and good selectivity for N-formylation of various aliphatic amines with CO2 and H2. Compared to previously reported heterogeneous catalysts for N-formylation, Pd0.25Cu0.75/Al2O3-0.1 demonstrates the lowest Pd loading but still achieves an unprecedented turnover number up to 527. Further mechanistic studies suggest that carbamate and formate are critical intermediates in N-formylation of amines with CO2 and H2 over a catalyst of Pd0.25Cu0.75/Al2O3. This mechanochemical strategy provides an opportunity for green and economical synthesis of heterogeneous metal catalysts.