Selective N‐Methylation of N‐Methylaniline with CO₂ and H₂ over Cu/In₂O₃ Catalyst^†

Abstract

Comprehensive Summary N ‐Methylation of amines with CO 2 and H 2 is a potential approach for CO 2 utilization because N ‐methylated amines can be used as solvents and organic intermediates. In 2 O 3 ‐supported Cu (Cu/In 2 O 3 ) acts as an effective heterogeneous catalyst for N ‐methylation reaction of N ‐methylaniline (MA) with CO 2 and H 2 , showing higher N,N ‐dimethylaniline (DMA) selectivity than other supported Cu catalysts. On one hand, the dispersion of Cu can be improved by the defective In 2 O 3 support. On the other hand, In 2 O 3 support is active in the dissociative adsorption of CO 2 through C—O bond breaking. In addition, the H 2 dissociation ability of In 2 O 3 can also be enhanced by Cu. The combination of Cu and In 2 O 3 is effective in the activation of CO 2 , the adsorption of intermediate N ‐methylformanilide (MFA), the hydrogenation of MFA to DMA and the prohibition of C—N bond cleavage side reactions, thereby enhancing the reaction rate of MA conversion and the selectivity to DMA.