Synthesis of Mesoporous Pd<sub><i>x</i></sub>Cu<sub>1–<i>x</i></sub>/Al<sub>2</sub>O<sub>3</sub>-<i>y</i> Bimetallic Catalysts Via Mechanochemistry for Selective <i>N</i>-Formylation of Amines with CO<sub>2</sub> and H<sub>2</sub>
Qizhuang Zou, Junji Chen, Yizhou Wang, Jiarui Gu, Fei Liu, Tianxiang Zhao
Abstract
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.