Co-based heterogeneous catalysts from well-defined α-diimine complexes: Discussing the role of nitrogen

• Published in: Journal of catalysis 2017-07, Vol.351, p.79-89
• Main Authors: Formenti, Dario, Ferretti, Francesco, Topf, Christoph, Surkus, Annette-Enrica, Pohl, Marga-Martina, Radnik, Jörg, Schneider, Matthias, Junge, Kathrin, Beller, Matthias, Ragaini, Fabio
• Format: Article
• Language: English
• Subjects: Cobalt; Heterolytic activation; Hydrogenation; Kinetic; Nitro compounds
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2017.04.014

[Display omitted] •Seven Co-based catalysts were prepared by pyrolysis of α-diiminic complexes.•Excellent chemoselectivity was observed in the case of substituted nitro compounds.•There was correlation between N content/free pyridinic-N and activity.•Heterolytic activation of H2 was proposed on the basis of kinetics. Ar-BIANs and related α-diimine Co complexes were wet impregnated onto Vulcan® XC 72 R carbon black powder and used as precursors for the synthesis of heterogeneous supported nanoscale catalysts by pyrolysis under argon at 800°C. The catalytic materials feature a core-shell structure composed of metallic Co and Co oxides decorated with nitrogen-doped graphitic layers (NGr). These catalysts display high activity in the liquid phase hydrogenation of aromatic nitro compounds (110°C, 50 bar H2) to give chemoselectively substituted aryl amines. The catalytic activity is closely related to the amount and type of nitrogen atoms in the final catalytic material, which suggests a heterolytic activation of dihydrogen.