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 H 2 treatments at 523−750 K. The N-coordinated Co(II) sites remained cationic in H 2 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 H 2 started at about 473 K, indicating a much lower thermal stability of Cu(II) in H 2 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.

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The selective oxidation of 1,6-hexanediol with O 2 to product aldehydes and acids occurs readily in water over supported Pt nanoparticles. The initial turnover frequency of 0.54 s −1 (at 343 K and 1 MPa O 2 ) decreases significantly with reaction time because of product competitive adsorption and irreversible adsorption of unknown strongly bonded species. To identify the poisoning species, in situ surface-enhanced Raman spectroscopy (SERS) and solid-state 13 C nuclear magnetic resonance (NMR) spectroscopy were applied in this work. In situ SERS during 1,6-hexanediol oxidation revealed an accumulation of di-σ-bonded olefinic species with features at ∼1150 and ∼1460 cm −1 on the poisoned Pt surface. Consistent with SERS, 13 C NMR spectroscopy of a Pt catalyst deactivated by oxidation of 13 C-labeled 1,4butanediol revealed a CC peak associated with ethylene. Molecules containing olefinic groups are 2 orders of magnitude more effective at competing for Pt surface sites in comparison to the aldehyde and acid products from alcohol oxidation. The poisoning olefinic species were generated by decarbonylation of product aldehyde (as revealed by head space analysis) and could be easily removed from the deactivated catalyst by mild treatment in H 2 .

This work focuses on the synthesis of supported Rh materials and study of their efficacy as pre‐catalysts for the oxidative alkenylation of arenes. Rhodium particles supported on silica (Rh/SiO2; ∼3.6 wt% Rh) and on nitrogen‐doped carbon (Rh/NC; ∼1.0 wt% Rh) are synthesized and tested. Heating mixtures of Rh/SiO2 or Rh/NC with benzene and ethylene or α‐olefins and CuX2 {X=OPiv (trimethylacetate) or OHex (2‐ethyl hexanoate)} to 150 °C results in the production of alkenyl arenes. When using Rh/SiO2 or Rh/NC as catalyst precursor, the conversion of benzene and propylene or toluene and 1‐pentene yields a ratio of anti‐Markovnikov to Markovnikov products that is nearly identical to the same ratios as the molecular catalyst precursor [Rh(μ‐OAc)(η2‐C2H4)2]2. These results and other observations are consistent with the formation of active catalysts by leaching of soluble Rh from the supported Rh materials.