N‑Formylation of Amines with CO2 and H2 Using Pd–Au Bimetallic Catalysts Supported on Polyaniline-Functionalized Carbon Nanotubes

• Published in: ACS sustainable chemistry & engineering Vol. 5; no. 3; pp. 2516 - 2528
• Main Authors: Ju, Pengpeng, Chen, Jinzhu, Chen, Aibing, Chen, Limin, Yu, Yifeng
• Format: Journal Article
• Language: English
• Published: American Chemical Society 06.03.2017
• Subjects: Electronic property; Formylation; Bimetallic catalyst; Hydrogenation; Carbon dioxide
• ISSN: 2168-0485; 2168-0485
• DOI: 10.1021/acssuschemeng.6b02865

Bimetallic Pd–Au catalyst was prepared by depositing the Pd–Au alloy nanoparticles on polyaniline-functionalized carbon nanotubes (PANI-CNT) and the resulting Pd–Au/PANI-CNT catalyst exhibited excellent catalytic activity for the N-formylation of pyrrolidine using CO2/H2. The structural and electronic properties of the Pd–Au/PANI-CNT was characterized by X-ray powder diffraction (XRD), nitrogen adsorption–desorption, transmission electron microscopy (TEM), high angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), and X-ray photoelectron spectroscopy (XPS). Under optimized conditions, an N-formyl­pyrrolidine yield of 98.3% was obtained from pyrrolidine and CO2/H2 at 125 °C by using Pd–Au/PANI-CNT with a Pd/Au molar ratio of 1:1. Our research further reveals that Pd atoms should be the true active sites for the hydrogenation reaction and the N-formylation reaction might occur mainly over Pd atoms or over the interface between Pd atoms and Au atoms for the bimetallic Pd–Au/PANI-CNT catalyst. The enhanced catalytic performance of bimetallic Pd–Au/PANI-CNT is mainly related to beneficial interactions between Pd atoms and Au atoms, leading to changes of the electronic properties of the formed bimetallic Pd–Au nanoparticles.