Tailoring Active Cu2 O/Copper Interface Sites for N-Formylation of Aliphatic Primary Amines with CO2 /H2

Abstract

Heterogeneously catalyzed N-formylation of amines to formamide with CO₂ /H₂ is highly attractive for the valorization of CO₂ . However, the relationship of the catalytic performance with the catalyst structure is still elusive. Herein, mixed valence catalysts containing Cu₂ O/Cu interface sites were constructed for this transformation. Both aliphatic primary and secondary amines with diverse structures were efficiently converted into the desired formamides with good to excellent yields. Combined ex and in situ catalyst characterization revealed that the presence of Cu₂ O/Cu interface sites was vital for the excellent catalytic activity. Density functional theory (DFT) calculations demonstrated that better catalytic activity of Cu₂ O/Cu(111) than Cu(111) is attributed to the assistance of oxygen at the Cu₂ O/Cu interface (O_inter ) in formation of O_inter -H moieties, which not only reduce the apparent barrier of HCOOH formation but also benefit the desorption of the desired N-formylated amine, leading to high activity and selectivity.

Keywords: Aliphatic Primary Amines; CO2 Conversion; Formamide; N-Formylation.