Atomically Dispersed Co and Cu on N‑Doped Carbon for Reactions Involving C–H Activation

• Published in: ACS catalysis 2018-05, Vol.8 (5), p.3875-3884
• Main Authors: Xie, Jiahan, Kammert, James D, Kaylor, Nicholas, Zheng, Jonathan W, Choi, Eunjin, Pham, Hien N, Sang, Xiahan, Stavitski, Eli, Attenkofer, Klaus, Unocic, Raymond R, Datye, Abhaya K, Davis, Robert J
• Format: Article
• Language: English
• Subjects: alcohol oxidation; coordination environment; C−H activation; heterogeneous catalyst; in situ XAS; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; MATERIALS SCIENCE; N-doped carbon; nonprecious metal; propane dehydrogenation
• ISSN: 2155-5435; 2155-5435
• DOI: 10.1021/acscatal.8b00141

Atomically dispersed Co­(II) cations coordinated to nitrogen in a carbon matrix (Co-N-C) catalyze oxidative dehydrogenation of benzyl alcohol in water with a specific activity approaching that of supported Pt nanoparticles. Whereas Cu­(II) cations in N-doped carbon also catalyze the reaction, they are about an order of magnitude less active compared with Co­(II) cations. Results from X-ray absorption spectroscopy suggest that oxygen is also bound to N-coordinated Co­(II) sites but that it can be partially removed by H2 treatments at 523–750 K. The N-coordinated Co­(II) sites remained cationic in H2 up to 750 K, and these stable sites were demonstrated to be active for propane dehydrogenation. In situ characterization of Cu­(II) in N-doped carbon revealed that reduction of the metal in H2 started at about 473 K, indicating a much lower thermal stability of Cu­(II) in H2 relative to Co­(II). The demonstrated high catalytic activity and thermal stability of Co-N-C in reducing environments suggests that this material may have broad utility in a variety of catalytic transformations.